Abdominal Aortic Aneurysms: Clinical Guidelines

List of Abbreviations

EVAR – endovascular aneurysm repair

ACT – activated clotting time

BP – blood pressure

AAA – abdominal aortic aneurysm

TAA – thoracic aortic aneurysm

ALT – alanine aminotransferase

Anchor*** – non-absorbable soft tissue anchor***

Anticoagulants – B01A Antithrombotic agents

IAA – iliac artery aneurysm

ASA – acetylsalicylic acid**

AST – aspartate aminotransferase

BB – beta-blockers

BAO – balloon aortic occlusion

IIA – internal iliac artery

SMA – superior mesenteric artery

IAAA – inflammatory aortic aneurysm

DAPT – dual antiplatelet therapy

APA – accessory renal artery

ЕОК – European Society of Cardiology

GI – gastrointestinal

IMH – intramural hematoma

ACE inhibitors (ACEI) – angiotensin-converting enzyme inhibitors

IADA – isolated abdominal aortic dissection

IFU – instructions for use

CTA of the abdominal aorta – computed tomography angiography of the abdominal aorta

CEUS – contrast-enhanced ultrasound

CABG – coronary artery bypass graft surgery with or without cardiopulmonary bypass

MAA – mycotic aortic aneurysm

CE-MRA – contrast-enhanced magnetic resonance angiography (single region)

MR angiography – magnetic resonance angiography (single region)

MSCT – multislice computed tomography

MSCTA CA – computed tomography coronary angiography

MET – metabolic equivalent

LMWH – low molecular weight heparin (heparin group)

EIA – external iliac artery

UFH – unfractionated heparin (sodium heparin**)

CIA – common iliac artery

RPV – renal parenchyma volume

BV – blood volume

OSR – open surgical reconstruction

DOACs – direct oral anticoagulants (antithrombotic agents)

HS – horseshoe kidney

PET-CT – positron emission tomography combined with computed tomography using tumorotropic radiopharmaceuticals

PAU – penetrating atherosclerotic ulcer

РКИ – randomized controlled trial

RCS – Russian Society of Cardiology

rAAA – ruptured abdominal aortic aneurysm

eGFR – estimated glomerular filtration rate, assessment of nephron function via creatinine clearance (Rehberg's test)

sAAA – suprarenal abdominal aortic aneurysm

AXR – abdominal X-ray

RF – Russian Federation

REBOA – resuscitative endovascular balloon occlusion of the aorta

EDS – Ehlers-Danlos syndrome

LDS – Loeys-Dietz syndrome

Statins – HMG-CoA reductase inhibitors

Stent-graft*** – endovascular stent-graft for the abdominal aorta***

Coronary artery stent*** – drug-eluting bioresorbable coronary artery stent***; drug-eluting coronary artery stent with a bioresorbable polymer coating***; drug-eluting coronary artery stent with a non-resorbable polymer coating***

TAAA – thoracoabdominal aortic aneurysm

TAT – triple antithrombotic therapy

Thienopyridines – antiplatelet agents other than heparin

TSH – thyroid-stimulating hormone

US – ultrasound examination

DUS of the aorta – duplex ultrasound scanning of the aorta

RF – risk factors

COPD – chronic obstructive pulmonary disease

CA – celiac axis

HR – heart rate

ECG – electrocardiogram recording

Aortic endografting – aortic endografting using a stent-graft***

Juxta-AAA – juxtarenal abdominal aortic aneurysm

LCE – level of confidence of evidence

GRS – grade of recommendation strength

ESVS – European Society for Vascular Surgery

ESC – European Society of Cardiology

CHA2DS2VASc – risk assessment scale for stroke and thromboembolic complications in patients with atrial flutter and atrial fibrillation.

** – the drug is included in the list of vital and essential drugs

*** – medical device implanted when providing medical care under the state guarantee program for free medical care to citizens

# – off-label prescription of a medicinal product not approved by state regulatory bodies and not mentioned in the instructions for use.

Terms and Definitions

Aneurysm – pathological vessel dilation with a diameter increase of more than 2 times compared to normal or a localized bulging of the wall.

Symptomatic aneurysm – an abdominal aortic aneurysm (AAA) presenting with the clinical triad: abdominal and/or back pain (or symptoms of internal organ compression), a pulsatile abdominal mass, and hypotension.

Endoleak – incomplete exclusion of the aneurysmal sac with continuous blood inflow into the sac following EVAR

Proximal neck of an infrarenal abdominal aortic aneurysm – a segment of the aorta with normal diameter, extending from the level of the renal artery origins to the beginning of the aortic dilation.

Juxtarenal abdominal aortic aneurysm – an abdominal aortic aneurysm distal to the renal arteries, but in close proximity to them.

Pararenal abdominal aortic aneurysm – an abdominal aortic aneurysm involving one or both renal arteries.

Suprarenal abdominal aortic aneurysm – an abdominal aortic aneurysm involving the visceral segment of the aorta, containing the superior mesenteric artery (SMA) and the celiac axis (CA), and specifically classified as a type IV thoracoabdominal aneurysm if it reaches the crura of the diaphragm.

True aneurysm – an aneurysm whose walls are composed of the structural elements of the vascular wall.

False aneurysm – a blood-filled cavity located in tissues outside the artery, but communicating with it through an opening in the wall.

Thesis-recommendation – a statement reflecting the procedure and correctness of performing a particular medical intervention with proven efficacy and safety.

Level of Certainty of Evidence (LoE) – the degree of confidence that the estimated effect of a medical intervention is true [1].

Level of Evidence (LoE) – the degree of certainty in the reliability of the intervention's effect and that following the recommendations will bring more benefit than harm in a specific situation [1].

1. Brief information on the disease or condition

Clinical practice guidelines reflect the most common practice for an average patient. However, in an individual case, based on scientific evidence, local clinical protocols, logistical and financial features, the decision may be reasonably modified by consensus of the cardiovascular team.

1.1 Definition of the disease or condition

Aneurysm is a term originating from the Ancient Greek word ἀνεύρυσμα, meaning dilation or widening of a blood vessel. In domestic literature, an abdominal aortic aneurysm is defined as its pathological dilation with a diameter increase of more than 2 times compared to normal or a localized bulging of the wall [2]. Another definition, based on ultrasound measurement of the outer diameter of the aorta, indicates that an aneurysm should be understood as an abdominal aorta diameter of 3.0 cm or more, which is usually more than 2 standard deviations greater than the mean diameter in men [3]. This definition has a sensitivity of 67% and a specificity of 97% for predicting the need for AAA reconstruction within 10 years [4]. The specificity and sensitivity of abdominal aortic duplex ultrasound in detecting AAA in asymptomatic patients reaches 100%. To date, there is no clear consensus on the rules for measuring dimensions using ultrasound data, but the most accurate is considered to be the measurement of the anteroposterior size in a plane perpendicular to its axis [5]. On average, the diameter of the abdominal aorta in the infrarenal segment is 18-22 mm. For women and certain populations of Asian descent, establishing a lower threshold value may be more appropriate due to a higher frequency of ruptures [6,7]. AAA is diagnosed when the abdominal aorta expands to more than 3.0 cm in diameter [8].

AAA rupture is defined as acute bleeding from an AAA beyond the true wall of the aorta with the accumulation of blood in the retroperitoneal and/initial intraperitoneal space. Most commonly, a two-stage rupture occurs, where the initial tear of the wall and bleeding from the aorta lead to collapse and are tamponaded by a thrombus, which is dislodged upon blood pressure elevation, leading to the second stage of rupture. Multi-stage ruptures occur when the site of rupture and hematoma are retroperitoneally located.

The most widely accepted definition of an iliac artery aneurysm (IAA) is vessel dilation of more than 1.5 times compared to its normal diameter [9]. In general, a common iliac artery (CIA) dilation ≥ 18 mm in men and ≥ 15 mm in women, and an internal iliac artery (IIA) dilation ≥ 8 mm is considered aneurysmal [9–11].

Another aortic disease, first described by Walker et al. in 1972 [12], is inflammatory abdominal aortic aneurysm (IAAA), accounting for 4-7% of all AAAs [13,14].

It is characterized by:

• atypical thickening of the aneurysm wall,

• shiny white perianeurysmal and retroperitoneal fibrosis,

• dense adhesions of adjacent intra-abdominal structures.

Penetrating atherosclerotic ulcer (PAU), first described in 1934 [15], is defined as ulceration of an atherosclerotic plaque extending beyond the aortic intima, resulting in the formation of hematomas within the aortic wall, the number of which may vary. Such lesions typically occur in elderly patients with systemic atherosclerosis and comorbidities. Based on a literature review, the estimated incidence of PAU is 1% in the population of patients with vascular diseases, with PAU in the abdominal segment (11-24%) occurring less frequently than in the thoracic segment (76-86%), although multiple lesions and associated aneurysms may be observed [16–20].

Saccular AAAs are considered a distinct nosological entity and are defined as spherical aneurysms involving only a portion of the aortic circumference [21]. In all cases, infection should be ruled out, and if present, appropriate treatment must be administered [22].

1.2 Etiology and pathogenesis of the disease or condition (group of diseases or conditions)

Most commonly, aneurysms of the aorta and peripheral arteries result from medial degeneration caused by complex biological mechanisms. Traditionally, it is believed that most aneurysms arise due to degenerative atherosclerotic changes, while other data indicate that many forms of aneurysms occur in response to altered levels of tissue metalloproteinases, which contributes to the disruption of the arterial wall integrity. Mycotic or primary infected aortic aneurysms (MAAs) develop due to the lodgment of septic emboli in the vasa vasorum, as a result of hematogenous spread during bacteremia, or by direct extension of an adjacent infection, leading to infectious degeneration of the arterial wall and aneurysm formation. The term "mycotic" was coined by Osler in 1885 due to the mushroom-like appearance of the aneurysms, which is misleading since most MAAs are caused by common microorganisms, including Gram-positive bacteria—mainly various species of staphylococci and enterococci—as well as Streptococcus pneumoniae and species of the genus Clostridium. Among Gram-negative bacilli, various Salmonella species are predominantly found, but Coxiella burnetii, mycobacteria, and fungi can also be identified [23–26]. Most patients with MAAs are male and tend to be younger (mean age 69-70 years) than patients with degenerative non-infected aneurysms (74-78 years) [22,27].

The pathogenesis of inflammatory abdominal aortic aneurysm (IAAA) remains unknown. Autoimmune mechanisms likely play an important role in the onset of this chronic inflammatory reaction, either as a result of a local pathological process based on an inflammatory response to atherosclerotic plaque components or as a manifestation of a systemic disease [28]. Based on immunological studies, a classification of immunoglobulin (Ig) G4-related and non-IgG4-related inflammation has been proposed, emphasizing the immunological role in the disease development [29–32]. The majority of IAAAs belong to the group of chronic periaortitis (idiopathic perianeurysmal retroperitoneal fibrosis). At the time of diagnosis, the age of these patients is 62-68 years, which is approximately 5-10 years younger than patients with degenerative AAA. The majority of patients are male (M:F ratio [6-30]:1), heavy smokers (85-90%) with a history of arterial hypertension, coronary artery disease (CAD), and peripheral artery disease (PAD).

Isolated infrarenal abdominal aortic dissection (IAAD) is rare and occurs much less frequently than abdominal aortic dissection combined with thoracic aortic dissection [33]. Dissection is caused by an intimal tear through which blood flows into the adjacent space, forming a false lumen. The entry tear typically occurs below or at the level of the renal arteries (82%) [34]. Concomitant abdominal aortic aneurysm (AAA) is present in 41% of patients with clinical manifestations of IAAD [33,35]. Intramural hematoma (IMH) represents a collection of blood within the aortic wall without an intimal tear or entry site on imaging, and it rarely occurs in the abdominal aorta alone.

Risk factors for AAA development

Smoking is the most important risk factor for the development of AAA. The odds ratio for this association is > 3 [36,37] and is higher in women [38,39]. Other risk factors include age, atherosclerosis, hypertension, ethnicity, and a family history of AAA [36,38]. Unique twin registry studies conducted in Sweden and Denmark indicate that the hereditary contribution may be as high as 70% [40,41].

The risk of AAA development in individuals with diabetes mellitus, particularly type 2, is approximately twice as low as in those without it [42,43].

Thus, advanced age, male sex, smoking, and a family history of AAA are considered the main risk factors for AAA development. The number of cardiovascular risk factors and the prevalence of peripheral artery disease correlate directly with abdominal aortic diameter, and the presence of coronary artery disease is associated with a 2.29-fold increase in the risk of having an AAA (p < 0.0001) [44,45].

Although classical cardiovascular risk factors are the primary cause of AAA development, younger and middle-aged patients (< 60 years) require a specialized diagnostic approach to identify underlying genetic and/or connective tissue disorders. More than 30 hereditary conditions that can potentially manifest as aortic or arterial aneurysms have been described. The same hereditary aortic disorder, typically associated with the thoracic aorta, may also affect the abdominal aorta, albeit to a much lesser extent, specifically Marfan syndrome, vascular Ehlers-Danlos syndrome (vEDS), Loeys-Dietz syndrome (LDS), arterial tortuosity syndrome, and aneurysm-osteoarthritis syndrome [24,46–48].

Mutations in genes encoding extracellular matrix components (e.g., fibrillin-1, collagen type III alpha 1 chain, collagen type IV alpha 5 chain); vascular smooth muscle cell contractile apparatus (e.g., aortic smooth muscle alpha-2 actin, cGMP-(cyclic guanosine monophosphate)-dependent protein kinase type I); and the transforming growth factor-beta signaling pathway (e.g., TGFBR1, 2, SMAD family member 3, TGFB3) are known to be associated with an increased risk of abdominal aortic pathology and aneurysm formation. Individuals with identical mutations may exhibit significant clinical variability [49].

Natural clinical course of AAA

In most patients, the natural course of small AAAs is characterized by a progressive increase in diameter. The RESCAN study, an individual patient data meta-analysis of more than 15,000 patients with AAA 3.0–5.5 cm in diameter, demonstrated no difference in aneurysm growth rate between men and women, averaging 2.2 mm/year; smoking increases the aneurysm growth rate by 0.35 mm/year (approximately 16%), whereas diabetes mellitus decreases the aneurysm growth rate by 0.51 mm/year (approximately a 25% reduction) [50].

Within the studied diameter range, an exponential increase in the mean growth rate was observed, from 1.3 mm/year for aneurysms 3.0 cm in diameter to 3.6 mm/year for aneurysms 5.0 cm in diameter. Aneurysm growth rate figures have not changed over the past 25 years [51].

1.3 Epidemiology of the Disease or Condition

Currently, the incidence of abdominal aortic aneurysms in the Russian Federation ranges from 10 to 40 cases per 100,000 population depending on the region, compared to 36.2 in the USA [2,52]. Over the past 20 years, the prevalence of AAA has decreased, which is partly attributed to a decline in the smoking population [36,53,54]. The prevalence of AAA increases with patient age, with over 80% occurring in individuals older than 60 years. Most studies show that the prevalence of AAA among women is 4 to 8 times lower than among men. In 89–96% of cases, abdominal aortic aneurysms are infrarenal in location and may be associated with iliac artery aneurysms in 28% of cases.

Aneurysms are detected in 0.16–1% of all autopsies and represent the tenth leading cause of human death. The incidence of abdominal aortic aneurysm rupture is 5.6–7.5 cases per 100,000 population.

The incidence of mycotic aortic aneurysms accounts for up to 1.3% of all aortic aneurysms in Western countries and is reported to be higher in East Asia [23–26]. Proposed diagnostic criteria for mycotic aortic aneurysms are presented in Table PB-1.

1.4 Features of Coding the Disease or Condition

Aortic aneurysm and dissection (I71)

I71.3 – Abdominal aortic aneurysm, ruptured

I71.4 – Abdominal aortic aneurysm, without mention of rupture

1.5 Classification of the disease or condition

Anatomical classification of aortic aneurysms

The thoracoabdominal aortic aneurysm (TAAA) classification proposed by Stanley E. Crawford in 1986 remains widely accepted (Figure 1) [55,56]. This classification describes the extent of an aortic aneurysm based on proximal and distal anatomical boundaries and the involvement of visceral arteries. The choice of surgical approach, clamping site, and reconstruction techniques depends on the extent of the aneurysm.

Figure 1. Crawford classification of thoracoabdominal aortic aneurysm (TAAA) types.

This classification is useful for describing surgical approaches, the extent of aortic reconstruction, and the risk prediction of spinal cord ischemia and other perioperative complications, the risk assessment of which is largely based on the degree of aortic involvement. This classification system assumes that the clamping site and anastomosis line are located near the origin and termination of the aneurysmal dilatation, which is not typical for endovascular interventions. In endovascular vessel wall reconstruction, extended healthy segments of the aorta with unaltered walls, located several centimeters proximal and distal to the anastomosis lines, are selected as landing zones for the endovascular abdominal aortic stent-graft*** (Figure 2).

Figure 2. Landing zones for the endovascular abdominal aortic stent-graft***. The proposed classification includes zones 0–3 (from the ascending aorta to the distal boundary of the aortic arch), 4–5 (from the proximal to the distal boundary of the thoracic aorta), 6–8 (visceral aorta), 9 (infrarenal aorta), and 10–11 (iliac arteries).

This means that the area of aortic aneurysm reconstruction extends proximally (often into the thoracic aorta) compared to that typically used in open surgical reconstruction. Thus, for the same degree of aortic disease, the size of the segment to be replaced may vary depending on the choice of open or endovascular technique, as well as the design of the endovascular abdominal aortic stent-graft***. This leads to significant differences between traditional open and endovascular vessel wall reconstruction, since increasing the length of the covered aorta in the proximal direction (during an endovascular procedure) may be accompanied by a higher risk of spinal cord ischemia and other perioperative complications than the anatomical classification suggests, although this does not necessarily lead to an increased risk of a symptomatic or clinically significant complication.

Tables 1 and 2 illustrate the typical correlation between the anatomical classification and the extent of endovascular vessel wall reconstruction, based on the segment where the proximal landing zone of the endovascular abdominal aortic stent-graft*** is located and the extent of the covered aortic segment. For patients who have previously undergone open or endovascular reconstruction of the ascending aorta, arch, thoracic aorta, or abdominal aorta, a classification encompassing the total extent of the aortic intervention is used. For example, if open replacement was performed in the proximal thoracic aorta, distal endovascular vessel wall reconstruction down to the level of the infrarenal aorta would be described as "completion of type II TAAA reconstruction" [57].

Table 1. Correlation between the anatomical classification of aneurysms and the extent of aortic reconstruction based on the number of covered aortic segments

Table 2. Classification of complex abdominal aortic aneurysms (AAA) and correlations between open surgical and endovascular vessel wall reconstruction

The classifications of abdominal aortic aneurysms by localization, size, and clinical course are of the greatest importance.

By localization:

A.V. Pokrovsky classification (Figure 3):

• proximal segment of the abdominal aorta involving visceral branches;

• infrarenal segment of the aorta without involvement of the bifurcation;

• infrarenal segment of the aorta involving the aortic bifurcation and iliac arteries;

• total lesion of the abdominal aorta.

Figure 3. Classification of abdominal aortic aneurysms according to A.V. Pokrovsky

By size:

• Small aneurysms (D 3–5 cm);

• Medium (D 5–7 cm);

• Large (D greater than 7 cm);

• "Giant" (8–10 times exceeding the diameter of the infrarenal aortic segment).

By clinical course:

Asymptomatic:

• absence of any complaints;

• aneurysm is an incidental finding during non-invasive diagnostics (complex ultrasound examination of the abdominal cavity organs, computed tomography of the abdominal cavity organs, and magnetic resonance imaging of the abdominal cavity organs).

Painless:

• subjective sensations of pulsation in the abdomen;

• objective palpation by a physician of a pulsatile painless mass in the abdomen.

Painful stage of the disease:

• tenderness appearing upon palpation of the abdominal mass;

• typical pain in the abdomen and lumbar region;

• atypical clinical symptoms: abdominal, urological, ischioradicular symptom complexes.

Stage of complications:

• threatened rupture;

• rupture, breakthrough;

• dissection;

• non-cardiogenic arterial embolization.

Several classifications of isolated iliac artery aneurysms (IAA) have been proposed [58–60]. Reber's anatomical classification by types I–IV appears well suited for comparing outcomes of various anatomical formations (Figure 4), whereas Farny's classification is based on assessing the suitability of the neck for endovascular aortic repair, which may change over time depending on medical devices and surgical technique. Degenerative aneurysms, pseudoaneurysms, penetrating ulcers, dissecting aneurysms, mycotic aneurysms, and traumatic aneurysms exist [61].

Isolated IAA most frequently affect the common iliac artery (Reber type I) and less frequently the external iliac artery (Reber type IV) [62–65]. According to available data, their total incidence accounts for up to 7% of all aortoiliac segment aneurysms, and 12–48% of all isolated IAAs are bilateral [63,65,66]. The majority of isolated IAA cases occur in men (90%) and are diagnosed in the seventh and eighth decades of life [64,66,67].

Figure 4. Reber classification of isolated iliac artery aneurysms [59].

1.6 Clinical presentation of the disease or condition

In many cases, an aortic aneurysm is completely asymptomatic. Symptoms may occur upon the formation of a large aneurysmal sac compressing surrounding structures: cough, dyspnoea, hoarseness (due to recurrent laryngeal nerve compression), upper extremity oedema (resulting from superior vena cava or brachiocephalic vein compression), painful or impaired swallowing (due to esophageal compression) in large thoracic aortic aneurysms; persistent or intermittent abdominal pain or discomfort, a sensation of abdominal "pulsation", a feeling of gastric fullness after minimal food intake in large abdominal aortic aneurysms [68].

2. Diagnostics, medical indications and contraindications for diagnostic methods

At a minimum, all patients should have a medical history taken and undergo a clinical examination, functional assessment including a general (clinical) blood count, blood sodium, potassium, and chloride levels, including assessment of renal function, and an electrocardiogram.

Additional studies, including resting echocardiography and pulmonary function tests, depend on the specific condition of the patient as described below.

2.1 Complaints and Anamnesis

The course of AAA is usually clinically asymptomatic.

The main symptoms or signs of an intact AAA are pain or tenderness upon palpation in the area of AAA localization or radiating to the back or genitals. Symptoms are associated with the formation of a large aneurysmal sac compressing surrounding structures: duodenal obstruction, lower extremity oedema, ureteral obstruction, cough, dyspnoea, hoarseness (due to recurrent laryngeal nerve compression), upper extremity oedema (resulting from superior vena cava or brachiocephalic vein compression), painful or impaired swallowing (due to esophageal compression) in large thoracic aortic aneurysms, persistent or intermittent abdominal pain or discomfort, a sensation of abdominal "pulsation", a feeling of gastric fullness after minimal food intake in large abdominal aortic aneurysms, or distal embolism [69].

Symptomatic AAAs manifest with abdominal and/or back pain, tenderness upon palpation or embolic phenomena, symptoms of compression of surrounding organs, but without disruption of the aortic wall integrity.

The classic triad consisting of arterial hypotension, abdominal and/or back pain, and a pulsatile abdominal mass is present in approximately 50% of patients with a ruptured aneurysm (rAAA). The most common misdiagnoses are renal colic and myocardial infarction.

RCC I C (LoE 5 GoR C)

Comment: in case of aneurysm rupture, signs are usually more pronounced (haemodynamic instability, pallor, abdominal and/or back pain, abdominal distension, and rarely primary aortoenteric or arteriovenous fistula) [69].

2.2 Physical Examination

Physical examination may reveal a pulsatile mass; however, the sensitivity of abdominal palpation for detecting AAA is < 50% [70] and lower in patients with a waist circumference greater than 100 cm. Thus, abdominal palpation is not a reliable method for diagnosing AAA.

2.3 Laboratory Diagnostics

RCC I C (LoE 5 GoR C)

RCC I C (LoE 5 GoR C)

• In patients at high risk of complications before AAA surgery, with known or suspected cardiovascular disease (CVD), it is necessary to perform biomarker assays: measurement of blood levels of troponins T and I, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) [72–75].

RCS I C (Level of Evidence 4, Grade of Recommendation C)

• Routine use of biomarker assays (e.g., measurement of blood levels of troponins T and I, and N-terminal pro-B-type natriuretic peptide (NT-proBNP)) for preoperative risk stratification is not recommended in patients prior to AAA intervention [73–75].

ESVS/ESC III C (Level of Evidence 5, Grade of Recommendation C)

Comment: Biomarker assays (e.g., measurement of blood levels of troponins T and I, and N-terminal pro-B-type natriuretic peptide (NT-proBNP)) should not be used routinely for preoperative risk stratification, but can be considered selectively in high-risk patients [73–75], such as those with low functional capacity or suspected clinically significant coronary artery disease.

• In patients undergoing abdominal aortic aneurysm repair, preoperative renal function assessment by blood creatinine testing and eGFR calculation is recommended, and patients with severe renal impairment (estimated glomerular filtration rate < 30 mL/min/1.73 m²) should be referred to a nephrologist [76,77].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comment: Despite the lack of established criteria for the degree of renal impairment requiring referral to a nephrologist, an eGFR < 60 mL/min can be classified as evidence of significant renal impairment, and < 30 mL/min as severe renal impairment requiring urgent nephrology referral.

Patients with severe renal impairment (e.g., chronic kidney disease stage 4 or 5; eGFR < 30 mL/min/1.73 m²) should be evaluated by a nephrologist to optimize renal function before elective aortic repair. Patients with mild to moderate renal impairment (i.e., chronic kidney disease stage 2 or 3; eGFR < 60 and > 30 mL/min/1.73 m²) should receive adequate hydration prior to AAA repair, especially when intravenous contrast media are administered [76].

• In patients undergoing elective abdominal aortic aneurysm repair, it is recommended to assess the preoperative nutritional status by measuring blood albumin concentration, with an albumin concentration < 2.8 g/dL (28 g/L) used as a threshold value for preoperative correction [78].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comment: Based on observational data from 15,000 patients undergoing AAA repair, 30-day mortality, reintervention rates, and pulmonary complications increased in the presence of hypoalbuminemia following both open (n = 4,956) and endovascular (n = 10,046) AAA repair [78]. Therefore, nutritional status must be assessed prior to aortic surgery for risk stratification.

An albumin concentration < 2.8 g/dL should be classified as severe reduction, which is associated with significantly worse outcomes [78]. In this situation, nutritional deficiencies should be corrected prior to elective open repair and elective endovascular AAA repair (EVAR), even though the efficacy of this measure has not been evaluated in RCTs in patients with AAA. Referral to a clinical dietitian may be appropriate and should be considered based on the severity and quality of the nutritional deficiency.

2.4 Instrumental Diagnostics

Comprehensive abdominal ultrasound (US) and color duplex sonography (CDS) of the aorta are first-line imaging modalities for detecting and determining management strategies for small AAAs, possessing high sensitivity and specificity [79,80]. Currently, an ultrasound technique for the abdominal aorta has been developed to detect asymptomatic forms of AAA in high-risk individuals [81]. Comprehensive abdominal ultrasound is used as a first-line method to detect AAA in the emergency department setting, where detecting the presence of the disease and its complications is diagnostically critical [82,83].

However, studies evaluating the accuracy of diameter measurements in emergency settings have not been conducted. Imaging limitations include:

• obesity or excessive bowel gas;

• changes in aortic diameter during the cardiac cycle;

• lack of serial image reconstruction for planning endovascular abdominal aortic stent-graft placement***

• difficulty in visualizing the suprarenal aorta and inability to visualize the thoracic aorta.

• In all patients with suspected AAA, comprehensive abdominal ultrasound and aortic color duplex sonography (CDS) are recommended as the first stage of examination to confirm the diagnosis, determine further management tactics, and provide follow-up [3,42,70,81,84].

RCS I C (Level of Evidence 4, Grade of Recommendation C)

• In all patients with AAA undergoing aortic color duplex sonography (CDS) to determine its dimensions, it is recommended to perform measurements in a plane perpendicular to the longitudinal axis of the aorta, which changes in the presence of aortic tortuosity. Various diameters can be measured/recorded: anteroposterior, transverse, and maximum in any direction. The position of the measurement calipers must be explicitly recorded in the study protocol [79,80,85].

RCS I C (Level of Evidence 2, Grade of Recommendation B)

Comment: in a review by Beales, intraobserver reproducibility coefficients for anteroposterior and transverse diameter measurements ranged from 1.6 to 7.5 mm and 2.8 to 15.4 mm, respectively [86], which supports the advisability of using the anteroposterior diameter as the primary measurement plane.

Physical examination is unable to detect inflammatory abdominal aortic aneurysms (IAAA). The capabilities of aortic CDS are largely determined by the class of equipment used and patient characteristics (abdominal girth, bowel gas, etc.), whereas computed tomography angiography (CTA) of the abdominal aorta has high accuracy for detecting IAAAs [60,87].

With the expanding use of cross-sectional imaging modalities, IAAAs are increasingly detected at an asymptomatic stage.

Computed tomography angiography (CTA) of the abdominal aorta plays a key role in assessing the pathological process, its extent, as well as in selecting the treatment method and planning surgical intervention. CTA of the abdominal aorta is also indicated as an imaging modality for complicated forms of aortic aneurysms, diagnosing aneurysm rupture, and serves as an important follow-up method after reconstructive surgery [88].

The principles of ultrasound measurement also apply to CT measurement; in patients with AAA undergoing abdominal CTA, measurements must be performed in a plane perpendicular to the longitudinal axis of the aorta, which changes in the presence of aortic tortuosity.

• In all patients with suspected or confirmed diagnosis of AAA based on comprehensive abdominal ultrasound and/or aortic color duplex sonography to confirm the diagnosis, as well as in symptomatic patients to assess the extent of the pathological process, rule out aneurysm rupture and other complications, select a treatment method, plan surgical intervention, rule out aneurysm rupture, and follow-up after reconstructive surgery, it is recommended to perform computed tomography angiography (CTA) of the aorta [8,85,86,89,90].

ESC/RCS I B (Level of Evidence 3, Grade of Recommendation B)

Comment: Limitations of computed tomography angiography (CTA) of the aorta include radiation exposure and the need for iodinated radiocontrast agents. Contraindications to their administration include impaired renal function, a history of severe allergies, and elevated thyroid hormone levels. If these abnormalities are detected, prior to the examination, a consultation with a nephrologist (Initial appointment (examination, consultation) with a nephrologist) and/or an allergist (Initial appointment (examination, consultation) with an allergist-immunologist) may be required.

RCS I C (LEL 3, GRD B)

Comment: It should be noted that diameters measured by complex abdominal ultrasound and CTA of the abdominal aorta frequently do not match, which is particularly important when evaluating values close to the diameter threshold for surgical intervention. This discrepancy is likely primarily due to inadequate reporting standards regarding the determination of the aortic axis, measurement plane, and location of measurement markers, although differences in equipment also contribute. Most commonly, this results in the diameter measured by CTA of the abdominal aorta being smaller than that measured by complex abdominal ultrasound; up to 70% of AAAs with a diameter of 50–55 mm on complex abdominal ultrasound have a diameter of more than 55 mm on CTA of the abdominal aorta [91]. In CTA of the abdominal aorta, the most accurate measurement of aortic diameter is considered to be in the orthogonal plane encompassing the entire wall thickness [8].

• In patients with suspected or confirmed AAA based on complex abdominal ultrasound and/or duplex ultrasound of the aorta, as well as in symptomatic patients, it is recommended to consider magnetic resonance (MR) angiography (single region) to assess the extent of the pathological process, rule out aortic rupture, and evaluate other complications [71].

RCS IIb C (LEL 5, GRD C)

Comment: Magnetic resonance (MR) angiography of the aorta (single region) is used less frequently than CTA of the abdominal aorta; contraindications include claustrophobia and the presence of metallic implants. However, MR angiography of the aorta (single region) does not involve radiation or the administration of iodinated radiocontrast agents and, therefore, has an advantage over CTA of the abdominal aorta when repeat AAA imaging is required. Data on the use of MR angiography of the aorta (single region) in routine clinical practice for patients with AAA are limited, both for MR angiography (single region) and contrast-enhanced magnetic resonance angiography (single region) (CE-MRA).

• In patients with suspected inflammatory-infectious etiology of AAA, including mycotic AAAs, and infection of vascular grafts and endovascular stent-grafts for the abdominal aorta***, it is recommended to consider positron emission tomography combined with computed tomography ([18F]FDG-PET/CT) to verify the etiology of AAA and for follow-up [92,93].

RCS IIb C (LEL 4, GRD C)

Comment: [18F]FDG-PET/CT allows for the localization and quantification of the metabolic activity of cells, including inflammatory cells. [18F]FDG-PET/CT is an additional imaging modality for the diagnosis and monitoring of pathological changes in the aorta associated with inflammatory aneurysm [92], aortic infection including mycotic AAAs [47], and infected vascular grafts and endovascular stent-grafts for the abdominal aorta***. Aside from these indications, [18F]FDG-PET/CT is primarily used for research purposes.

The diagnosis of inflammatory AAA is based on a combination of clinical and laboratory parameters and the results of imaging studies, including complex abdominal ultrasound and CTA of the abdominal aorta [94].

RCS IIb C (LEL 5, GRD C)

• Routine prescription of cardiopulmonary exercise testing is not recommended for patients prior to AAA intervention [95].

ESVS/ESC III C (LEL 5, GRD C)

Comment: Cardiopulmonary exercise testing has gained popularity in many types of major non-cardiac surgical procedures to identify patients who require pre-operative cardiac and pulmonary conditioning. Despite numerous publications, there are limited data to recommend routine testing in patients prior to AAA intervention [95].

ESC I C (LEL 4, GRD C)

Comment: In uncomplicated stable coronary artery disease (CAD), specific ECG signs of myocardial ischemia at rest are usually absent. The only fairly specific sign of CAD on a resting ECG is a Q wave following a prior acute myocardial infarction (AMI). Isolated T-wave changes are non-specific and must be correlated with the clinical presentation and data from other studies [97].

RCS I C (LEL 5, GRD C)

• Routine screening for asymptomatic carotid artery stenosis before abdominal aortic aneurysm repair is not recommended [99–102].

ESVS/ESC III C (LEL 4, GRD C)

Comment: The benefit of screening for carotid disease prior to AAA repair has not been evaluated [102], and available data do not support routine preoperative screening. The ESVS carotid guidelines provide a weak recommendation for selective screening for asymptomatic carotid stenosis in patients with multiple vascular risk factors. This recommendation aims to optimize risk factor control and medical therapy, thereby reducing late cardiovascular events and mortality, rather than to identify candidates for invasive carotid interventions [99,100,102,103].

• In all patients prior to elective abdominal aortic aneurysm repair, it is recommended to consider pulmonary function testing (PFT) [76,104].

RCS IIb (LEL 5, GRD C)

Comment: Patients with a forced expiratory volume in 1 second (FEV1) or forced vital capacity (FVC) of less than 70% of the predicted value are at increased risk of perioperative pulmonary complications, as are patients with an FEV1/FVC ratio of less than 0.65 [104].

• Targeted chest radiography is recommended for patients prior to abdominal aortic aneurysm repair [76,105].

RCS IIa C (LEL 5, GRD C)

Comment: However, routine targeted chest radiography is redundant since CTA of the entire aorta (including the thorax) is typically performed, and furthermore, it does not improve preoperative risk stratification [105].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

• In hemodynamically stable patients with suspected abdominal aortic aneurysm rupture, urgent CTA of the abdominal aorta is recommended as the preferred imaging modality, though the choice of available imaging method is determined by the vascular team [107–110].

ESVS/ESC I B (LEL 2, GRD B)

• In hemodynamically unstable patients with suspected abdominal aortic aneurysm rupture, it is recommended to consider urgent CTA of the thoracoabdominal aorta to evaluate the feasibility of endovascular repair prior to transferring the patient to the operating room, though the choice of available imaging method is determined by the vascular team [109,111,112].

ESVS/ESC IIa B (LEL 4, GRD C)

Comment: if the patient is not sufficiently stable for MSCT, they should be transported directly to the operating room for verification of retroperitoneal hematoma, emergency open surgical intervention (emergency OSI), or intraoperative imaging to determine suitability for endovascular aneurysm repair (EVAR).

Intraoperative abdominal aortography, with or without digital subtraction angiography (DSA), can be an urgent compromise solution to determine initial suitability for EVAR and select the device with subsequent measurements performed either during fluoroscopy or intravascular ultrasound of the vessel wall [113].

Features of population screening for AAA

The natural history of abdominal aortic or iliac artery aneurysms is characterized by a long asymptomatic course, and their first manifestations are associated with the development of complications, the most formidable of which is rupture. Among instrumental diagnostic methods during AAA screening, ultrasound imaging methods should be preferred.

• For the early detection of abdominal aortic aneurysms and prevention of rupture, it is recommended to consider screening examination in men older than 65 years [114–118].

ESVS/ESC I A (Leveled Evidence 1, Grade of Recommendation A)

• A single screening focused abdominal ultrasound (comprehensive) to detect AAA is recommended:

  - Men aged ≥ 65 years who have ever smoked are recommended to undergo ultrasound screening to detect AAA [119].

  - Men or women aged ≥ 65 years who are first-degree relatives of patients with AAA are recommended to undergo ultrasound screening to detect AAA [120].

RSS I C (Leveled Evidence 3, Grade of Recommendation B)

ESVS/ESC IIb C (Leveled Evidence 4, Grade of Recommendation C)

Comment: The natural history of abdominal aortic or iliac artery aneurysms is characterized by a long asymptomatic course, and their first manifestations are associated with the development of complications, the most formidable of which is rupture. Early and timely detection of AAA and monitoring the dynamics of its growth is an urgent task to improve treatment outcomes. Among instrumental diagnostic methods during AAA screening, ultrasound imaging methods should be preferred.

Comprehensive abdominal ultrasound allows reliable visualization of the infrarenal aorta in 98.5% of patients [3], but it should be borne in mind that in some cases aorta visualization may be difficult (1-2%). In complex cases, the patient should be re-examined by a qualified ultrasound or functional diagnostics physician after inpatient preparation.

Since AAA is frequently combined with other peripheral artery aneurysms (iliac, femoral, popliteal), these patients are regularly screened for AAA as well as other peripheral artery aneurysms. In a study involving 190 patients operated on for popliteal artery aneurysm, 39% developed a new aneurysm during a mean follow-up of 7 years, and 43% of these were AAAs [121].

• If AAA is detected in a patient during non-vascular examination, it is recommended to refer them to a cardiovascular surgeon (initial cardiovascular surgeon consultation/examination) for further evaluation and treatment [116,122].

ESVS/ESC I A (Leveled Evidence 1, Grade of Recommendation B)

2.5 Other Procedures

Genetic counseling for hereditary connective tissue disorders includes a thorough clinical examination focusing on skeletal, ocular, cutaneous, and craniofacial features, detailed family history mapping with a three-generation pedigree, and collection of clinical data from first-degree relatives [123,124]. Appropriate genetic counseling and testing of the patient and family members should be initiated early not only to determine appropriate medical/surgical management for the individual patient, but also to identify implications for family members.

• In patients with abdominal aortic aneurysm whose disease cannot be explained solely by a non-genetic cause, particularly in patients < 60 years of age or those with a family history, genetic counseling (initial consultation/examination by a clinical geneticist, cardiologist experienced in managing this patient group) is recommended prior to genetic testing [123–126].

ESVS/ESC I C (Leveled Evidence 2, Grade of Recommendation B)

3. Treatment, including drug and non-drug therapies, diet therapy, and pain management

3.1 Conservative Treatment

Currently, there is no specific medical therapy that slows the growth rate of abdominal aortic aneurysms in the preoperative period [127,128]. Several different drug classes have been evaluated in randomized trials for their ability to reduce the growth rate of small aneurysms. To date, the efficacy of no drug class has been proven, including #doxycycline** (ATC: J01AA02), beta-blockers, ACE inhibitors [90,127,128], while other studies are still ongoing.

• In patients with AAA and mean SBP ≥ 130 mmHg or mean DBP ≥ 80 mmHg, the use of antihypertensive agents is recommended to reduce the risk of cardiovascular complications [71].

RSS I C (Leveled Evidence 5, Grade of Recommendation C)

• In patients with AAA and signs of aortic atherosclerosis, statin therapy is recommended in accordance with current clinical guidelines for lipid metabolism disorders [71,129].

RCC I C (LoE 5 GoR C)

Comment: a recent meta-analysis of more than 20 cohort studies involving 80,428 patients showed that statin use is associated with a mean reduction in AAA growth rate of 0.82 mm/year (95% confidence interval 0.33, 1.32, P = 0.001, I2 = 86%). Statin treatment is also associated with a lower risk of rupture (odds ratio 0.63, 95% confidence interval 0.51, 0.78, P < 0.0001, I2 = 27%), and preoperative statin use was associated with lower 30-day mortality after elective AAA repair (odds ratio 0.55, 95% confidence interval 0.36, 0.83, P = 0.005, I2 = 57%). It was concluded that statin therapy is associated with reduced AAA progression, rupture rates, and lower perioperative complications and mortality after elective AAA repair [72].

• In patients with AAA and concomitant atheroma and/or penetrating atherosclerotic ulcer, it is recommended to consider the use of low-dose #acetylsalicylic acid (ASA)** 75-100 mg (ATC: B01AC06) once daily, orally, indefinitely, barring contraindications, for the prevention of thrombotic complications [71].

RSS IIA C (Leveled Evidence 5, Grade of Recommendation C)

• Moderate- or high-intensity statin therapy is recommended for patients with AAA regardless of aneurysm diameter to reduce its growth rate, rupture frequency, and the rate of perioperative complications and mortality after elective AAA reconstruction [130].

ESVS/ESC IIa B (Leveled Evidence 2, Grade of Recommendation B)

Comment: a recent meta-analysis of more than 20 cohort studies involving 80,428 patients showed that statin use is associated with a mean reduction in AAA growth rate of 0.82 mm/year (95% confidence interval 0.33, 1.32, P = 0.001, I2 = 86%). Statin treatment is also associated with a lower risk of rupture (odds ratio 0.63, 95% confidence interval 0.51, 0.78, P < 0.0001), and preoperative statin use was associated with lower 30-day mortality after elective AAA repair (odds ratio 0.55, 95% confidence interval 0.36, 0.83, P = 0.005). It was concluded that statin therapy is associated with reduced AAA progression, rupture rates, and lower perioperative complications and mortality after elective AAA repair [130]. A study evaluating medications taken by 12,485 British patients with a registered diagnosis of AAA showed that 5-year survival was significantly higher in patients receiving statins (68% vs. 42%), antithrombotic agents (64% vs. 40%), or antihypertensive agents (62% vs. 39%) compared with AAA patients not taking these drugs. A more detailed analysis of the antihypertensive agents used showed that diuretics may be less effective than other drug classes [131].

• When mycotic aortic aneurysm (MAA) is suspected, systemic antibacterial therapy administered intravenously is recommended both prior to EVAR and prior to open surgery [8,132–134].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

• Empirical antibacterial therapy targeting Staphylococcus aureus and gram-negative bacilli is recommended to be initiated as soon as culture results are obtained and continued in patients with negative culture results [8, 132–137].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comments: The source of infection in patients with primarily infected aortic aneurysm cannot be identified in one-third of patients, nor can the causative pathogen in 21–40% [132, 138, 139].

The optimal management strategy for patients with infected abdominal aortic aneurysm (IAAA) remains uncertain, and it is preferred that all patients with IAAA are closely monitored by a multidisciplinary team.

• Conservative medical treatment with systemic corticosteroids is recommended for symptomatic aneurysms below the threshold diameter for repair in the presence of severe pain and weight loss associated with marked hydronephrosis, indicating perioperative difficulties [140].

RCS IIb C (LEL 4, GRD C)

Comment: The optimal dose and duration of medical treatment remain incompletely understood due to the lack of controlled clinical studies evaluating the long-term efficacy of systemic corticosteroids in IAAA [141–144].

• All patients with symptomatic inflammatory abdominal aortic aneurysms are recommended to receive medical anti-inflammatory treatment [94, 148–150].

ESVS/ESC IIa C (LE 4, GR C)

Acute-phase inflammatory markers (ESR, CRP) are not reliable markers on their own for determining management and follow-up strategies, as they often do not correlate with the metabolic assessment of the disease.

• All patients with a penetrating aortic ulcer, isolated abdominal aortic dissection, aortic pseudoaneurysm, or intramural hematoma are recommended to receive medical treatment, including blood pressure control [24, 151–153].

ESVS/ESC IIa C (LE 3, GR C)

Optimal Perioperative Medical Therapy

The use of beta-blockers in the perioperative period has been evaluated in RCTs. Current ESC guidelines provide for joint decision-making by the surgeon, cardiologist, and anesthesiologist-intensivist on a case-by-case basis [75]. Patients already taking beta-blockers should continue therapy at the appropriate dose.

• Regarding beta-blocker medical therapy, it is recommended to follow these provisions:

  1. in the perioperative period, continuation of previously prescribed beta-blocker therapy is recommended;

  2. in patients with two or more risk factors or an ASA score > 3, preoperative administration of beta-blockers is appropriate;

  3. in patients with coronary artery disease or myocardial ischemia, the question of preoperative beta-blocker administration should be considered;

  4. when prescribing beta-blockers, priority should be given to #bisoprolol** (ATC: C07AB07) at an initial dose of 1.25–2.5 mg/day, orally, long-term, with subsequent titration to the target dose of 10 mg/day [75].

ESVS/ESC IIa B (LE 5, GR C)

Comment: randomized trials evaluating the use of beta-blockers in the first 24 hours after vascular surgery either failed to demonstrate benefit in low-risk patients (POBBLE trial [154], MaVS trial [155]) or showed an increase in all-cause mortality, hypotension, and stroke rates, despite a reduction in perioperative myocardial infarction (POISE trial [156]).

• Immediate administration of large doses of beta-blockers without dose titration is not recommended in patients with AAA [75, 157].

ESVS/ESC III C (Level of Evidence 5, Grade of Recommendation C)

• Patients with AAA are recommended to initiate statin therapy prior to (ideally at least 4 weeks before) elective AAA surgery to reduce the rate of cardiovascular complications [75, 158, 159].

ESVS/ESC I A (LE 4, GR C)

Comment: recent results of a meta-analysis of 1 randomized and 36 cohort studies (n = 134,290 patients) showed that compared with non-statin users, patients receiving statins had significantly lower long-term mortality (odds ratio 0.67; 95% confidence interval 0.59–0.75; P < 0.001; I2 = 71.7%) and lower short-term mortality after abdominal aortic aneurysm surgery (odds ratio 0.51; 95% confidence interval 0.36–0.73; P < 0.001; I2 = 81.4%). No significant differences were found between statin users and non-users regarding perioperative cardiovascular complications after endovascular aneurysm repair. These data indicate that statin use is associated with a significant reduction in long-term and short-term mortality in patients following AAA repair [160].

• Patients scheduled for aortic surgery are recommended to be considered for supervised physical exercise in the preoperative period to reduce the rate of postoperative cardiac, pulmonary, and renal complications, as well as to shorten hospital stay [161].

RSC IIb B (LE 2, GR B)

Comment: A recent RCT in the UK demonstrated that supervised preoperative physical exercise is beneficial for patients undergoing open or endovascular aortic surgery, as it reduces the incidence of postoperative cardiac, pulmonary, and renal complications and shortens hospital stay [161].

Antithrombotic therapy

Monotherapy with ASA** (ATC: B01AC06) or thienopyridines (e.g., clopidogrel** [ATC: B01AC04]) does not pose a risk of major bleeding during AAA repair [162]. Although such therapy is associated with an increased risk of bleeding after non-cardiac surgery, no increase in major bleeding episodes has been noted [163].

Therefore, antiplatelet monotherapy can be continued until endovascular or open repair to reduce thrombotic and cardiac risk.

• Regarding antithrombotic monotherapy in patients scheduled for AAA repair, it is recommended to:

• continue the prescribed monotherapy with ASA** 75–100 mg/day (ATC: B01AC06), 1 tablet once daily, in the perioperative period up to open and endovascular abdominal aortic aneurysm repair and indefinitely thereafter, in the absence of contraindications [163];

ESVS/ESC I B (LE 2, GR A)

• discontinue thienopyridine monotherapy (e.g., clopidogrel** [ATC: B01AC04] 75 mg orally once daily) 3–7 days prior and, if possible, switch to ASA** (ATC: B01AC06) [164].

ESVS/ESC I B (LE 4, GR C)

Comment: under certain circumstances, continuation of dual antiplatelet therapy (DAPT) may be required (see cardiac risk control), but this is likely to concern high-risk patients in whom the risk-benefit ratio for AAA repair must be carefully assessed [146]. Experience with dual therapy including more potent antithrombotic agents, such as #prasugrel (ATC: B01AC22) at a dose of 10 mg 1 tablet orally once daily and #ticagrelor** (ATC: B01AC24) at a dose of 90 mg 1 tablet orally twice daily, and reconstructive surgery for AAA is very limited, but it is likely associated with a high risk of major bleeding and should be avoided [151, 165, 166]. Treatment with vitamin K antagonists and direct oral anticoagulants (DOACs) should be discontinued at least five days (with international normalized ratio [INR] monitoring) and two days prior to surgery, respectively, to reduce the risk of significant bleeding. Depending on indications in the perioperative period, a short-acting anticoagulant such as low molecular weight heparin (LMWH) or unfractionated heparin (UFH) may be used.

Discontinuation of Dual Antiplatelet Therapy (DAPT)

There is a practice of switching patients from thienopyridines to LMWH 5–7 days before surgery.

• DAPT should be resumed as soon as possible in patients following AAA surgery, ideally within 48 hours [75, 157].

RCC I C (LoE 5 GoR C)

Comment: in case of high thrombotic risk, a loading dose of clopidogrel** 300–600 mg orally once, #prasugrel 60 mg once, or #ticagrelor** 180 mg once is administered orally. In case of high risk of postoperative bleeding, oral antiplatelet therapy is prescribed after 48–72 hours. To reverse the action of antiplatelet agents (B01AC Platelet aggregation inhibitors excluding heparin), blood transfusions are used, preferably under the control of platelet aggregation [75, 167].

• In patients receiving DAPT after percutaneous coronary intervention, it is recommended to consider postponing abdominal aortic aneurysm repair until transition to monotherapy. Alternatively, if AAA repair becomes necessary, EVAR performed while on DAPT can be considered [168,169].

ESVS/ESC IIb C (Level of Evidence 5, Grade of Recommendation C)

Comment: in patients undergoing percutaneous coronary intervention prior to AAA repair, the risk of coronary stent thrombosis is highest during the first 6 weeks after coronary stenting. For this reason, DAPT should not be discontinued during this period. If drug-eluting coronary stents were used, DAPT should not be stopped for 6 months [168,170,171]; therefore, elective AAA repair should generally be postponed if DAPT must be discontinued for surgery. Alternatively, EVAR can be performed in combination with DAPT. In patients with symptomatic AAA and CAD with complex coronary lesions, simultaneous on-pump or off-pump coronary artery bypass grafting (CABG) and open AAA repair are theoretical options in certain circumstances, but EVAR performed under local anesthesia is generally preferred immediately after CABG.

Discontinuation of Triple Antithrombotic Therapy (TAT)

Discontinuation of triple antithrombotic therapy should be carried out in accordance with current guidelines.

• In patients prior to AAA surgery, it is recommended not to discontinue low-dose ASA** (ATC: B01AC06) 75–100 mg orally, 1 tab. once daily; if discontinuation is possible per current guidelines, clopidogrel** is stopped at least 5 days prior (#ticagrelor** — 3–5 days prior, #prasugrel — 7 days prior), and anticoagulants (B01A Antithrombotic agents) 24–48–72 hours before the intervention (depending on bleeding risk and creatinine clearance) [157,170,172].

RSC I B (Level of Evidence 5, Grade of Recommendation C)

Management of Patients Receiving Antithrombotic Agents

Anticoagulant therapy is also associated with an increased risk of intra- and postoperative bleeding. In some patients with a low risk of thrombotic complications, anticoagulants can be discontinued before surgery, in which case the rules for their discontinuation must be followed. In other patients, discontinuing anticoagulants is impossible due to a high risk of thrombosis; therefore, the only solution may be changing the drug, its dosage, and timing of administration. Traditionally, DOACs are used for long-term therapy.

Vitamin K Antagonists

For many years, vitamin K antagonists (VKAs: warfarin**) were the only oral anticoagulants.

• In patients who cannot have VKA therapy discontinued prior to surgery due to a high risk of thromboembolic complications, bridging therapy (or bridge therapy) with LMWH or UFH is recommended [75,167,173].

RSC I B (Level of Evidence 5, Grade of Recommendation C)

Comment: there are patient groups in whom VKAs cannot be discontinued due to a high risk of thromboembolic complications:

• patients with mechanical heart valves or implanted biological valves (cadaveric sterile biological heart valve prosthesis***) within the last 3 months;

• patients after mitral valve repair within the last 3 months;

• patients after recent (within the last 3 months) venous thrombosis or embolism;

• atrial fibrillation with severe mitral stenosis;

• patients at high risk of thromboembolism (left ventricular thrombus, antithrombin deficiency, protein C and/or S deficiency, hereditary thrombophilia) [75,167,173].

This category of patients requires bridging therapy (or bridge therapy) with LMWH/UFH.

Standardly, VKAs are discontinued 3–5 days before the intervention (depending on the drug; warfarin** is stopped 5–7 days prior). Daily measurement of the international normalized ratio (INR) is then required; an INR ≤ 1.5 indicates that the patient can be operated on and LMWH/UFH administration can be started the next day.

LMWH dosage adjustment after subcutaneous administration is performed based on the patient's body weight and renal function; laboratory monitoring is not required. Patients at high risk of venous thromboembolism should be administered therapeutic doses twice daily. The last LMWH injection is given no later than 12 hours before the incision.

In patients with mechanical valve prostheses (mechanical bileaflet aortic valve prosthesis***, mechanical bileaflet mitral valve prosthesis***), there is more evidence for the effective use of UFH, so UFH administration is possible with the last injection 4 hours before the incision.

In the postoperative period, UFH/LMWH administration is resumed in the evening on the day of the intervention, based on hemostasis, usually 12 hours after surgery. VKAs are also resumed on the first postoperative day simultaneously with UFH/LMWH, with daily INR testing. The VKA dosage remains the same. When an INR ≥ 2.0 is reached, UFH/LMWH is discontinued; in the case of a mechanical prosthesis in the mitral position (mechanical bileaflet mitral valve prosthesis***), UFH is discontinued when INR > 2.5 [75,167,173].

Direct Oral Anticoagulants (DOACs)

• In patients prior to surgery, with normal creatinine clearance, it is recommended to routinely discontinue DOACs 2–3 half-lives before low bleeding risk surgeries and 4–5 half-lives before high bleeding risk surgeries, including aortic surgeries, i.e., 48 hours before aortic interventions. If creatinine clearance is less than 50 mL/min, dabigatran etexilate** is discontinued 96 hours prior [75,167,173].

RSC IIa B (Level of Evidence 5, Grade of Recommendation C)

Comment: DOAC intake for surgeries with minimal and low bleeding risk is resumed on the day of surgery or the following morning, while for high bleeding risk surgeries, DOACs are resumed 2 or more days later based on hemostasis, using bridging therapy [75,167,173].

• In the perioperative period, the use of DAPT or oral anticoagulants is not recommended for patients undergoing elective AAA repair [151].

ESVS/ESC III C (Level of Evidence 5, Grade of Recommendation C)

Specifics of Anticoagulant Therapy and DVT Prophylaxis

Although this is a standard strategy for elective AAA repair, intraoperative intravenous administration of UFH during open or endovascular repair for rAAA remains controversial. The risk of increased bleeding must be weighed against the benefits associated with the antiembolic effect of UFH [174,175]. Regardless of whether systemic anticoagulation is administered from the beginning, the administration of UFH and systemic anticoagulation during EVAR should be strongly considered immediately after the aneurysm is completely excluded from the circulation (while the delivery system and introducers are still in place) or once aortic control is established via balloon occlusion of the aorta (BOA). If anticoagulation is not performed during surgery, thrombectomy (iliac and femoral artery thromboembolectomy) or conversion to open surgery may be required due to the development of intravascular thrombosis.

• During ruptured abdominal aortic aneurysm repair, intraoperative administration of a systemic anticoagulant (UFH) is recommended after bleeding from the rupture site has been controlled [151].

ESVS/ESC IIa C (Level of Evidence 5, Grade of Recommendation C)

• In patients undergoing repair for rAAA, it is recommended to perform DVT prophylaxis based on the balance between DVT risk and bleeding risk [176,177].

ESVS/ESC IIa C (Level of Evidence 4, Grade of Recommendation C)

Comment: A rational approach is mechanical prophylaxis using sequential compression devices until the risk of major bleeding decreases. Once the high risk of major bleeding has subsided, pharmacological prophylaxis with LMWH or UFH can be initiated. In most patients, it can be safely started within 24–48 hours after surgery in the absence of signs of ongoing bleeding or clinically significant coagulopathy [178]. Such prophylaxis should be continued throughout the hospital stay, and in some patients even after discharge, depending on individual risk factors and mobilization status [178,179].

Systemic Antibiotic Prophylaxis

Numerous randomized trials have demonstrated the benefits of antibiotic prophylaxis in reconstructive arterial surgery [180]. Therefore, perioperative intravenous antibiotic prophylaxis is indicated before both open and endovascular AAA repair, with drug selection based on local institutional guidelines.

• All patients undergoing open or endovascular abdominal aortic aneurysm repair are recommended perioperative systemic antibiotic prophylaxis to prevent infectious complications [180].

ESVS/ESC I A (Leveled evidence 1, Grade of recommendation C)

3.2 Surgical Treatment

Threshold Aneurysm Size for Elective AAA Repair

The immediate decision regarding the aneurysm size at which reconstructive intervention should be performed is based on the balance between the risk of aneurysm rupture (which still results in mortality in > 80% of cases) [107,181] and the risk of postoperative mortality associated with aneurysm repair.

The CAESAR and PIVOTAL trials clearly defined surgical intervention strategies for surveillance groups in addition to reaching the diameter threshold: these included rapid aneurysm growth (> 1 cm per year and the onset of aneurysm-related symptoms) [182].

• In cases of rapid abdominal aortic aneurysm growth (≥ 1 cm/year), it is recommended to urgently refer the patient to a cardiovascular surgeon and perform additional imaging of the AAA [183–185].

ESVS/ESC IIa C (Leveled evidence 4, Grade of recommendation C)

• Patients with a symptomatic abdominal aortic aneurysm are recommended to be urgently referred to a cardiovascular surgeon [183,186,187].

ESVS/ESC I C (Leveled evidence 3, Grade of recommendation A)

Indications for surgery

Based on the follow-up data of patients with small AAAs, surgical treatment of AAA is currently indicated when it reaches a diameter of 5.5 cm (outer diameter), rapid growth (more than 1 cm per year), and the onset of symptoms associated with the AAA. This strategy is considered safe. Nevertheless, aneurysms of smaller diameter are also operated on in some countries. This is also the case in our country, where the threshold diameter was considered to be 5.0 cm [101]. Our experts derived this indication from the results of the ADAM and UkSAT trials, which state that more than 80% of aneurysms with a diameter of 4.9–5.5 cm at the time of screening were subsequently operated on [188,189].

Surgical treatment is recommended for:

• men with an AAA at an aneurysm diameter of 5–5.5 cm;

• women with an AAA and acceptable surgical risk at an aneurysm diameter of ≥ 4.5–5.0 cm;

• patients with an AAA presenting with rapid aneurysm growth—greater than 1.0 cm per year—for an urgent consultation with a cardiovascular surgeon (initial consultation/examination by a cardiovascular surgeon) for further evaluation [71].

ESVS/ESC IIa C (Leveled evidence 5, Grade of recommendation C)

Management Strategy for Patients Unsuitable for Early Intervention for AAA

A significant number of patients with AAA are not candidates for reconstructive surgery (including EVAR) due to comorbidities or limited life expectancy [190–192]. For these patients, cardiovascular risk reduction strategies are of particular importance. Observational data suggest that statins may reduce the risk of rupture of large AAAs [50,193] and that the risk of rupture is twice as high in current smokers [50,193].

• For patients who are not initially candidates for reconstructive surgery for AAA, further follow-up, referral to other medical specialists to optimize their physical condition, and subsequent reassessment are recommended [194,195].

ESVS/ESC IIa C (Leveled evidence 2, Grade of recommendation B)

Clinical Comorbidity Scoring Systems

Cardiac complications remain one of the primary indicators of outcomes, and several clinical scoring systems have been developed to determine the risk of cardiac events [105,196,197]. A modified scoring system developed by the Vascular Study Group of New England (Appendix G2) and recently proposed in the clinical practice guidelines for AAA is based on seven variables to predict patient mortality risk categories: low risk (0.12–1%), intermediate risk (1.7–4.9%), high risk (8–20%), and very high risk (31–70%) [8,72,198]. This system has been validated for infrarenal aneurysms and has not been studied in complex aortic aneurysms.

Assessment and Optimization of Surgical Risks

Open aortic repair is classified as a high-risk intervention (defined as a 30-day cardiovascular mortality or myocardial infarction risk of 5% or greater), whereas EVAR is classified as an intermediate-risk intervention with a cardiac risk of 1–5% [72].

Detailed guidelines for the assessment and reduction of surgical risks exist [75], a summary of which was recently published [199] and should be consulted for detailed information. This section provides a broad overview of relevant factors to consider when performing aortic reconstruction.

Cardiac Risk Control

Cardiac complications account for more than 40% of perioperative deaths after noncardiac surgical procedures [200–202]; therefore, the level of cardiac risk should be assessed clinically [97,203].

In the presence of active cardiovascular disease, such as unstable angina, decompensated heart failure, severe valvular heart disease, and significant arrhythmias, a cardiologist's consultation and appropriate treatment are required before planning AAA repair.

ESVS/ESC I B (Leveled evidence 5, Grade of recommendation C)

Comment: coronary angiography should be performed for the same indications as in non-surgical interventions and should not be used routinely for perioperative risk assessment before aortic surgery [75].

ESVS/ESC III B (Leveled evidence 5, Grade of recommendation C)

• In patients with severe aortic stenosis, evaluation and a consultation with a cardiovascular surgeon (initial consultation/examination by a cardiovascular surgeon) are recommended to determine the feasibility of surgical aortic valve replacement (SAVR)/transcatheter aortic valve implantation (TAVI) prior to elective abdominal aortic aneurysm repair [75,105,204,205].

ESVS/ESC I B (Leveled evidence 5, Grade of recommendation C)

Comment: aortic stenosis is the most significant valvular heart disease in the context of AAA repair because it increases the risks associated with blood loss, fluid shifts, and arrhythmias. In patients with severe aortic stenosis (defined as a mean gradient > 40 mmHg, valve area < 1 cm², and peak velocity > 4.0 m/s), SAVR/TAVI should be considered prior to elective AAA repair [75,105,204,206,207].

Perioperative management of patients with coronary artery disease and congestive heart failure should be carried out in accordance with current guidelines [75,105,157,208,209].

Renal Function Monitoring

Postoperative renal impairment leads to prolonged hospital stays and is a well-known predictor of high morbidity and long-term mortality [75,76,100,210]. Patients at particularly high risk include those with pre-existing renal failure, congestive heart failure, chronic obstructive pulmonary disease (COPD), peripheral artery disease (PAD), diabetes mellitus, or arterial hypertension [97,211,212]. In the context of open or endovascular AAA repair, pre-existing renal impairment is one of the most important predictors of perioperative morbidity and mortality [77,213,214].

• Adequate hydration is recommended for patients with renal impairment prior to elective abdominal aortic aneurysm repair. Following abdominal aortic aneurysm repair, monitoring of estimated glomerular filtration rate, fluid intake, and urine output is recommended to detect renal function decline and determine further management strategies [75,76].

ESVS/ESC I C (Leveled evidence 5, Grade of recommendation C)

• During endovascular repair of a complex abdominal aortic aneurysm, it is recommended to use a strategy of preserving renal function by reducing the dose of iodinated radiocontrast agent, discontinuing nephrotoxic drugs, and ensuring adequate hydration [151].

ESVS/ESC IIa C (Level of Evidence 5, Grade of Recommendation C)

Carotid artery stenosis management

• In patients with an abdominal aortic aneurysm and concomitant symptomatic carotid artery stenosis, it is recommended to consider the need for surgical intervention on the carotid arteries prior to aneurysm repair [103].

ESVS/ESC IIa A (Level of Evidence 5, Grade of Recommendation C)

Comment: patients with symptomatic internal carotid artery stenosis (<6 months) require treatment of the carotid stenosis prior to AAA repair to reduce the overall stroke risk. For the diagnosis and therapeutic management of symptomatic carotid artery disease, appropriate guidelines should be consulted [102,103].

• Routine prophylactic carotid intervention for asymptomatic carotid stenosis prior to abdominal aortic aneurysm repair is not recommended [103].

ESVS/ESC III C (Level of Evidence 5, Grade of Recommendation C)

Comment: prophylactic preoperative carotid endarterectomy or stenting of the brachiocephalic arteries does not provide a beneficial effect in patients with asymptomatic carotid stenosis, even in cases of severe lesions [103].

Elective AAA repair

Selection of surgical strategy

• Elective open AAA surgery is recommended to be performed in hospitals with an annual volume of at least 10–20 procedures per year. If the volume is lower, it is recommended to refer the AAA patient to a specialized regional or federal center for elective AAA surgery [215–221].

ESVS/ESC IIa C (LE 4, GR C)

Comments: The choice of surgical method should be discussed between the attending physician and the patient, and a number of factors must be taken into account when drawing up an individualized treatment plan for the patient. These include:

• favorable anatomy for EVAR;

• physiological reserves and absence of medical contraindications for surgical intervention;

• life expectancy;

• patient preferences;

• needs and expectations, including the importance of sexual function and anticipated compliance with the requirements for high-frequency lifelong surveillance and follow-up.

Thus, the decision on when and by what method to perform surgical intervention for AAA is extremely complex, and multiple factors must be considered and decisions made on an individual basis [222].

• In the majority of elderly patients with suitable anatomy and average population life expectancy, endovascular abdominal aortic aneurysm repair is recommended as the preferred treatment method [194,195,222–239].

ESVS/ESC I A (Level of Evidence 1, Grade of Recommendation B)

• In the majority of patients with a long life expectancy, open abdominal aortic aneurysm repair is recommended as the preferred treatment method [226,229–233,240–242].

ESVS/ESC I A (Level of Evidence 1, Grade of Recommendation B)

Comment: although EVAR should be considered the preferred treatment method in most patients, it is advisable to consider open surgery as a first-line strategy in younger patients without medical contraindications and with a life expectancy of >10–15 years. The estimated (mean) survival after elective AAA repair is approximately 9 years [243].

• In patients with limited life expectancy (e.g., patients with incurable cancer or severe heart failure), elective abdominal aortic aneurysm repair is not recommended [194,224].

ESVS/ESC III B (Level of Evidence 2, Grade of Recommendation B)

Patient selection for EVAR

Based on the aortic diameter and the length of the target proximal landing zone, the main aortic stent-graft*** is selected, and compliance of the proximal stent-graft*** landing zone is assessed in accordance with the instructions for use. Other characteristics include: angulation of the proximal aneurysm neck, presence of thrombi, geometric configuration (i.e., parallel walls), and calcification.

To determine dimensions and plan the preservation of side branches, accurate measurements should be made based on curved planar reformation images or multiplanar reconstructions with a straightened centerline of flow.

Severe vessel tortuosity and small iliac artery diameter (less than 6 mm) are the primary factors hindering standard EVAR procedures.

From the perspective of feasibility for standard endovascular aortic repair, the configuration of the aneurysm neck is an important factor. According to the Delphi consensus published in 2019, five criteria for unfavorable aneurysm neck anatomy are described: diameter, angulation, conical shape, and length of the aneurysm neck, as well as the presence of circumferential calcification [244,245].

• Standard endovascular aortic repair is not recommended for AAA patients with the following neck parameters: length less than 10 mm, width greater than 32 mm, neck angle sharper than 75°, circumferential calcification greater than 50%, and conical shape [244,245].

ESVS/ESC – none (Level of Evidence 5, Grade of Recommendation C)

3.2.1 Endovascular treatment of abdominal aortic aneurysms

Complex AAAs

Complex AAAs (Figure 5; Table 2) are defined as aneurysms involving the renal or mesenteric arteries, extending up to the level of the celiac trunk or diaphragm, but not extending into the thoracic aorta [196].

For complex AAAs, an anatomical classification system is frequently used, which includes the description of infrarenal aortic aneurysms with a short neck, 4–10 mm in length [246], and juxtarenal aortic aneurysms, defined by an infrarenal neck length of ≤4 mm, reaching the renal arteries but not extending beyond them [247]. In these two subgroups, the renal arteries originate from normal segments of the aorta and are not involved in the aneurysm. Pararenal aortic aneurysms are characterized by the involvement of at least one renal artery and extend up to the superior mesenteric artery, but not higher. Parasvisceral aortic aneurysms are characterized by the involvement of the renal arteries and the superior mesenteric artery, but not the celiac trunk. The term "suprarenal aortic aneurysm" is often used to combine pararenal and paravisceral aortic aneurysms into a single category. Type IV thoracoabdominal aortic aneurysms are defined as proximal extension of the aneurysm to the level of the celiac trunk or diaphragm.

Figure 5. Classification of abdominal aortic aneurysms (AAA), including infrarenal with a short neck (<10 mm) (A), juxtarenal (B), pararenal (C), paravisceral (D) aneurysms, and type IV thoracoabdominal aortic aneurysms (E).

• Percutaneous access during endovascular abdominal aortic aneurysm repair is recommended to be performed under imaging guidance [248–251].

ESVS/ESC IIa A (Level of Evidence 1, Grade of Recommendation A)

• During elective endovascular abdominal aortic aneurysm repair, it is recommended to consider regional anesthesia rather than total intravenous anesthesia [151,252–254].

ESVS/ESC IIb C (Leveled Evidence 4, Grade of Recommendation C)

Anatomical factors affecting EVAR strategy

Accessory renal arteries

• During endovascular aneurysm repair, it is recommended, whenever possible, to preserve large accessory renal arteries (>4 mm) or arteries supplying a significant portion of the kidney (>1/3) [151,255].

ESVS/ESC IIa C (Level of Evidence 3, Grade of Recommendation C)

Comment: The ESVS and SVS clinical guidelines suggest maintaining the patency of accessory renal arteries with a diameter greater than 4 mm in both open and endovascular treatment of AAA. Accessory renal arteries (ARAs) are present in 9–16% of patients undergoing EVAR, and approximately half of these cases undergo occlusion [255]. Potential consequences include: renal infarction with the risk of impaired renal function (especially in the presence of pre-existing renal insufficiency) and the risk of persistent type II endoleak [256]; open surgical repair should be considered as the preferred treatment option.

Parietal mural thrombus in the aorta

• To predict the risk of embolization during endovascular procedures, it is recommended to use quantitative assessment of the aortic mural thrombus (AMT) [257,258].

RSC IIa C (LoE 4 GoR C)

Comments: to simplify AMT assessment in clinical practice, Ribeiro et al. [257] proposed a classification system based on a scale from 0 to 10 for quantitative assessment of thrombus type (i.e., smooth or irregular), thickness, area involved, circumferential extent, and number of affected segments (Figure 6). To obtain a score using this system, analysis of the most severely affected aortic segment is performed using axial slices. This segment is chosen after examining the entire length of the aorta.

Figure 6. Measurement of the mural thrombus in the aorta (MTA) using quantitative computed tomographic angiography (CTA) based on the number of thrombus-affected segments, as well as the type, thickness, area, and circumference of the thrombus.

Assessment of iliofemoral access feasibility

• As with any aortic endovascular procedure, patients with AAA are recommended to undergo duplex ultrasound scanning of the lower extremity arteries and computed tomographic angiography of the abdominal aorta and iliac vessels to determine the feasibility of implant delivery [53,259].

RRR I C (LEL 4 GOR C)

Comment: A significant proportion of adverse events occurring during EVAR are access-related complications. To avoid such complications, it is necessary to assess the diameter, length, and other morphological features of the iliac and femoral arteries [53].

Options for preserving abdominal aortic branches

Parallel stent-grafts***

Currently known CHIMPS techniques (chimney, periscope, and sandwich) lack specific indications for use, and there is no standardization of practice between centers [260–266].

• For primary, single-, two-, or multi-stage and adjunctive procedures in patients with AAA, it is recommended to specify the timing: preoperative, intraoperative, or postoperative [267,268].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comment:

Description of methods for preserving abdominal aortic branches

There is an increasingly frequent use of staged and adjunctive procedures to extend landing zones or reduce the risk of complications, such as spinal cord injury [267–275]. Based on this, the following types of procedures can be distinguished: primary, staged, and adjunctive.

Primary procedure. The procedure that contributes most to the treatment of the aortic disease being operated on, including the preservation of renal and mesenteric arteries regardless of the chosen technique, is considered the main or primary procedure. The primary procedure can be performed in a single session (single-stage), two sessions (two-stage), or more sessions, including planned subsequent interventions such as occlusion of the aneurysm sac-feeding branch [262,265]. These subsequent expected procedures should not be described as "planned secondary interventions" since they are an obligatory component of the planned staged reconstruction strategy.

Single-, two-, or multi-stage procedures. The term "single-stage procedure" describes the treatment of aortic disease in a single operation. It applies when a second adjunctive operation is used before or after the main procedure. In these cases, the main operation as described above is specified, along with the specific indications for the additional operations.

Adjunctive procedures. An adjunctive procedure is any other procedure designed to improve the effects of the primary procedure. Such procedures include surgical debranching of an aortic segment using bypass (e.g., carotid-carotid bypass, aorto-celiac bypass), arterial branch stenting (e.g., in the presence of baseline stenosis), intercostal artery embolization, and enhancement of proximal fixation using bare-metal uncovered aortic stents.

New generation stent-grafts***

• For new-generation endovascular stent-grafts for the abdominal aorta*** based on existing platforms, particularly low-profile devices, long-term follow-up and evaluation of durability in prospective registries are recommended [276–278].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comment: when updates to existing platforms are used in clinical practice, it is necessary to acknowledge the need for long-term follow-up and evaluation in prospective registries with complete follow-up [277,278].

An alternative concept, termed endovascular aneurysm sealing (EVAS), consists of the complete exclusion of the aortic aneurysm sac using polymer-filled polyurethane bags surrounding PTFE-covered balloon-expandable stents. This approach was designed to prevent certain EVAR complications, including endoleak and stent-graft*** migration.

New and additional methods for preserving abdominal aortic branches

• If fenestrations or implantation of parallel endovascular stent-grafts for the abdominal aorta*** are required during EVAR, it is recommended to consider the use of anchors*** [279].

RRR IIb B (LEL 4 GOR C)

Comment: to ensure secure fixation of stent-grafts*** if proximal sealing after EVAR is expected to be inadequate due to a short or angulated neck, anchors*** [are used]. In a multicenter registry of 208 cases of primary prophylactic use of fixation devices, technical failure (3/57, 5.3%) and type I endoleak (2/45, 4.4%) were more common in patients with an aortic neck < 10 mm compared to > 10 mm: 1 out of 95 (1.1%) and 1 out of 73 (1.4%), respectively [279]. At a mean follow-up of 14 months in 130 patients, the prevalence of type Ia endoleak was 1.5% (n = 2).

Specific late complications of endovascular treatment

Long-term outcomes using stent-grafts for the abdominal aorta** (with additional components – branches and modifications – fenestrated), EVAR performed with parallel grafts for visceral arteries, as well as new concepts, particularly aneurysm sealing [280], may differ from outcomes with standard devices. Consequently, these complex EVAR procedures and new technologies may require modified follow-up schedules.

Significant adverse events [281,282]:

• All-cause mortality;

• Myocardial infarction;

• Respiratory failure requiring prolonged (> 24 hours beyond expected) mechanical ventilation or re-intubation;

• Renal function decline manifested as a drop in eGFR of more than 50% from baseline or newly initiated dialysis;

• Bowel ischemia requiring surgical resection or unresponsive to medical therapy;

• Major stroke;

• Paraplegia (grade 3).

System-specific complications

Postoperative complications in accordance with reporting standards for endovascular treatment of AAA and TAA include the following classification:

• Mild: complication resolved spontaneously or with minor intervention and did not lead to an increased length of hospital stay or irreversible deterioration;

• Moderate: complication required significant intervention or prolongation of hospital stay by more than 24 hours and resulted in minor permanent disability not affecting normal daily activities;

• Severe: complication requires major surgical intervention or treatment, may be accompanied by a prolonged recovery period, and is usually associated with prolonged or permanent disability, or results in death.

Endoleaks

Endoleak refers to the presence of blood flow within the aneurysm sac outside the graft after EVAR [283], which occurs in approximately one-third of cases [284], although the prevalence depends on the type of stent-graft used and the imaging modality performed during follow-up. The classification of endoleaks was proposed in the EVAR reporting standards [260,285,286]. The revised classification system is summarized in Figure 7.

Figure 7. Classification of endoleaks. IMA — inferior mesenteric artery.

The classification of endoleaks was revised, partly due to the preservation of side branches.

Type I endoleaks. Type I endoleaks are, by definition, related to persistent flow outside the stent-graft*** and, consequently, inadequate sealing at the attachment sites of the aortic stent-graft*** and its modular components. The newly proposed classification uses letter categories A, B, and C to designate attachment sites of fenestrated, branched, or parallel stent-grafts*** proximally, distally, and in the target vessel. The classification of type IC endoleaks expands the previous definition of endoleaks associated with an iliac occluder used in rare cases.

Persistent direct blood flow into the aneurysmal sac due to inadequate proximal (type IA) or distal (type IB) sealing of the stent-graft*** poses a hazard and is associated with a high risk of aneurysm rupture [287,288]. Direct blood flow may also occur due to lack of seal at the iliac artery occlusion site (type IC), in case of unilateral aorto-iliac reconstruction with a cross-over bypass. Type I endoleak requires immediate intervention to exclude the aneurysm from the pressurized circulation.

• In patients with type I endoleak following endovascular aneurysm repair (EVAR), it is recommended to evaluate the need for reintervention to achieve sealing, primarily using endovascular techniques [287,288].

ESVS/ESC IIa C (Leveled evidence 4, Grade of recommendation C)

• For endoleaks in the proximal fixation zone of the prosthesis following endovascular abdominal aortic aneurysm repair, among all endovascular intervention techniques, extension of the proximal stent-graft*** implantation zone using fenestrated and branched devices is recommended first and foremost [151,289–295].

ESVS/ESC IIa C (Leveled evidence 4, Grade of recommendation C)

Type II endoleaks. Type II endoleaks are associated with retrograde blood flow into the aneurysmal sac. They are often complex endoleaks with multiple inflow and outflow channels. Retrograde blood flow may originate from the lumbar arteries, inferior mesenteric artery, accessory renal arteries, or other collateral vessels. Because there is a stable collateral communication between the inferior mesenteric artery and the celiac trunk, a type II endoleak may arise from the celiac trunk if a fenestration or branch is absent for this vessel and stenting has not been performed. It frequently resolves spontaneously, and the risk of rupture is low (< 1%) [284,296,297]. In the presence of aneurysmal sac enlargement due to suspected type II endoleak, appropriate imaging should be performed to rule out other causes of enlargement, such as inadequate sealing or type III endoleak (junction, graft integrity, or suture holes) [297].

Various treatment methods for type II endoleak have been described. Endovascular treatment consists of transarterial, translumbar, and transcaval embolization of the aneurysmal sac and feeding vessels. Several embolic materials are used to treat type II endoleak [281]. Endovascular treatment is successful in 60-80% of cases; however, there is no clear definition of a successful intervention, which may affect the interpretation of these results. According to a systematic review, translumbar embolization may have a higher success rate with fewer complications [297].

• An increase in aneurysmal sac diameter by ≥ 1 cm detected during follow-up after endovascular abdominal aortic aneurysm repair using a single imaging modality and measurement technique is recommended to be considered as a justified threshold for significant enlargement [71].

ESVS/ESC I B (Leveled evidence 5, Grade of recommendation C)

• The issue of reintervention for type II endoleak following endovascular abdominal aortic aneurysm repair, primarily via endovascular methods, is recommended to be considered in the presence of significant aneurysm growth [71,297].

ESVS/ESC I B (LoE 3 GoR B)

• In case of persistent enlargement of the aneurysmal sac after attempted endovascular treatment(s) of type II endoleaks, elective open conversion with preservation or removal of the stent-graft*** is recommended [151,298–300].

ESVS/ESC IIa C (Leveled evidence 4, Grade of recommendation C)

Type III endoleaks. Type III endoleaks may result from stent-graft*** disconnection, inadequate overlap, fabric tear, or disconnection. Letters A, B, and C are also used to designate the localization of the endoleak within a specific modular component. Type IIIA endoleak describes inadequate overlap or connection between any of the modular components in the aorta or iliac vessels, including any proximal thoracic aortic stent-graft, fenestrated, or branched component. Type IIIB endoleak continues to be defined as a tear in the graft fabric, which may be further characterized as minor (< 2 mm) or major (≥ 2 mm). Finally, the new category of type IIIC is defined as inadequate overlap, connection, or disconnection between one or more target vessel bridging stents (connection tubes), or between a target vessel bridging stent (connection tube) and a cuff or fenestration of the aortic endoprosthesis.

• In patients with type III endoleak following endovascular abdominal aortic aneurysm repair, it is recommended to evaluate the need for reintervention, primarily using endovascular methods [287].

ESVS/ESC I C (LoE 3 GoR B)

Type IV endoleaks. Type IV endoleaks refer to blood flow through an intact aortic stent-graft due to porous fabric within the first 30 days after the procedure. This designation does not apply to graft fabric tears or persistent blood flow through the fabric for more than 30 days, which should be classified as a type IIIB endoleak.

Indeterminate endoleak. The term "indeterminate endoleak" refers to endoleaks detected on imaging studies that do not have a definite source.

Endotension. An increase in the aneurysmal sac of more than 5 mm without evidence of an endoleak on imaging studies is classified as endotension. It may occur due to an endoleak that is not detected because of suboptimal imaging or limitations of available imaging modalities.

Endotension can lead to AAA rupture, although this occurs extremely rarely and only isolated cases have been described in the literature [287].

• Significant enlargement of the aneurysmal sac size following endovascular abdominal aortic aneurysm repair without a visible endoleak on standard imaging is recommended to be considered as an indication for further diagnostic work-up using alternative imaging modalities to rule out an unidentified endoleak, alongside appropriate management [71,287,301–303].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

• In the presence of an endoleak accompanied by increased cardiac output, heart failure, or pulmonary embolism following endovascular repair of a ruptured abdominal aortic aneurysm into the inferior vena cava, it is recommended to consider endovascular closure of the aortocaval fistula [151].

ESVS/ESC IIb C (LoE 5 GoR C)

Comments: Changes in aneurysmal sac diameter should be described over a specific follow-up period. Reports of complex endovascular aortic repair should also indicate the clinical correlation between aneurysmal sac diameter and the presence of endoleaks or other complications. Because dimensions can change in all three planes, both sac volume and diameter are important parameters. "Aneurysmal sac enlargement" or "shrinkage" refers to an increase or decrease in diameter by more than 5 mm or measured volume by more than 5%, respectively.

Stent-graft*** migration is generally defined as displacement of the stent-graft*** by >10 mm relative to fixed anatomical landmarks confirmed on centerline-of-flow CT reconstructions, or any migration resulting in symptoms or reintervention [304]. Migration can lead to type I endoleak, separation of stent-graft*** modules, kinking, and occlusion. Risk factors for proximal migration include short proximal fixation, angulated neck, large aneurysm size, and stent-graft*** type [304–306]. The role of oversizing is controversial, but there is evidence that oversizing a stent-graft*** by more than 30% relative to the nominal size may increase the risk of migration [307,308]. Disease progression with neck expansion may be a cause of late migration and is associated with baseline neck diameter [309].

Table PB-2 summarizes important morphological and technical outcome measures, including diameter, length, volume, endoleak, attachment site dimensions, displacement, tortuosity, and branch vessel morphology.

3.2.2 Open reconstruction

Indications for open surgical repair

Main indications for open surgical repair of AAA:

• Degenerative AAA with favorable anatomy in patients with low risk of mortality and complications, and high life expectancy

• Degenerative AAA with unfavorable anatomy (complex AAA) in patients with low risk of mortality and complications

• Inflammatory AAA in severe hydronephrosis and presumably low risk of mortality and complications

• Mycotic AAA

• Thrombosed AAA and combination of AAA and Leriche syndrome

• AAA with accessory renal arteries

• AAA in patients with hereditary connective tissue disorders

• Performing open repair in the long-term period after EVAR

• AAA rupture in the setting of:

  – severe hemodynamic instability;

  – unfavorable anatomy;

  – extensive retroperitoneal hematoma;

  – presence of primary aortoduodenal fistula.

Types of grafts

There is no evidence to suggest that any single graft is superior to another [306].

Both knitted synthetic vascular grafts (Dacron) and expanded polytetrafluoroethylene (PTFE) grafts can be used in infrarenal AAA surgery. In juxta- and suprarenal aortic surgery, only knitted vascular grafts should be used.

Surgical approach

• The decision regarding the approach to the abdominal aorta in patients with AAA is recommended to be made taking into account the surgeon's preference and patient-related factors (including patient preference) [310].

ESVS/ESC I C (LoE 2 GoR A)

Comment: Midline laparotomy (along the linea alba from the xiphoid process to the pubic symphysis) is a widely used technique due to its versatility and relatively easy access to all abdominal organs. An alternative approach is a transverse subcostal incision below the rib cage, which provides good access to the juxtarenal, suprarenal, and celiac parts of the aorta. However, a Cochrane review found no clinically significant difference between midline and transverse incisions in general abdominal surgery [311], which was confirmed in a later RCT [310].

Basic principles of open aortic repair

To minimize the risk of thrombosis due to stasis, LMWH/UFH is generally administered systemically prior to cross-clamping. Acceptable doses range from 50 to 100 IU/kg [312], and the efficacy of heparin sodium** can be monitored using activated clotting time (ACT) testing to ensure adequate anticoagulation [313]. After the restoration of peripheral perfusion, a calculated dose of protamine sulfate** may be administered to neutralize UFH based on ACT results and the presence of diffuse bleeding.

• Prior to aortic cross-clamping, intravenous administration of #Heparin sodium** (50–100 IU/kg) is recommended to prevent thromboembolic complications [313].

ESVS/ESC I A (LoE 3 GoR B)

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

• During open repair of an abdominal aortic aneurysm, it is recommended to preserve blood flow to at least one internal iliac artery to reduce the risk of gluteal intermittent claudication and colonic ischemia [316–319].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

• The feasibility of preserving the renal bridge and accessory renal arteries with a diameter of > 3 mm is recommended to be considered in both open and endovascular repair of an abdominal aortic aneurysm associated with a horseshoe kidney [260, 320, 321].

ESVS/ESC IIa B (LoE 3 GoR B)

• A retroperitoneal approach for patients requiring open surgical or hybrid repair, when anatomically feasible, is recommended to be considered as the preferred surgical treatment option for abdominal aortic aneurysm associated with a horseshoe kidney [251, 321, 322].

ESVS/ESC IIa B (LoE 3 GoR C)

Inferior mesenteric artery and internal iliac arteries

The presence of retrograde blood flow from the IMA with a normal macroscopic appearance of the colon indicates that it is safe to ligate during open repair of AAA. Such ligation should be performed at the origin of the IMA to preserve blood flow in the left colic artery. Reconstruction of a patent IMA should be considered in cases of unsatisfactory retrograde blood flow and an increased risk of colonic ischemia, which is present in occlusion of the celiac trunk/superior mesenteric artery, after bowel resection, during prolonged aortic clamping, massive intraoperative and postoperative blood loss, and when blood flow to both internal iliac arteries is interrupted [53, 323–325]. For the same reason, it is suggested to preserve blood flow to at least one patent internal iliac artery.

• If inadequate pelvic perfusion with a risk of colonic ischemia is suspected, reconstruction of the inferior mesenteric artery during open abdominal aortic aneurysm repair is recommended [326, 327].

ESVS/ESC I B (LEL 2, GRD B)

Open aortic repair in the long-term period after endovascular treatment

• Open surgical repair of the aorta after endovascular treatment is recommended only in specialized centers [71].

ESVS/ESC I C (Leveled evidence 5, Grade of recommendation C)

Comment: When performing open aortic repair after endovascular treatment, a number of technical issues must be addressed, namely: choosing the surgical approach, determining the level of aortic clamping, developing a strategy regarding the previously placed stent-graft***, creating the proximal anastomosis, and performing other adjunctive procedures [328].

If open repair after endovascular treatment is performed to treat a secondary aortoduodenal fistula, complex small bowel surgery should be performed after the vascular procedure is completed [328].

When performing open repair after endovascular treatment, 30-day mortality is higher compared to primary open AAA repair due to the extent of the surgical approach, longer operative time, higher level of aortic clamping, the need for a bifurcated graft, and a higher incidence of intraoperative and postoperative bleeding. According to recently published data, mortality during open repair after endovascular treatment reaches 22% [328].

• In selected cases of loss of seal in the proximal fixation zone of the stent-graft*** following endovascular abdominal aortic aneurysm repair, it is recommended to consider planned conversion to open repair as an alternative to complex endovascular interventions, provided the surgical risk is acceptable [151, 289].

ESVS/ESC IIb C (LoE 5 GoR C)

3.2.3 Laparoscopic aortic reconstruction

Laparoscopic aortic surgery is a minimally invasive alternative to open surgery in cases where EVAR is not indicated [329, 330].

Laparoscopic treatment methods for AAA include a totally laparoscopic approach, a laparoscopically assisted approach (laparoscopic dissection with endoaneurysmorrhaphy through a minilaparotomy), a hand-assisted laparoscopic approach, and a robotic laparoscopic approach.

These techniques are technically demanding and require extensive expertise in laparoscopic surgery.

• Laparoscopic abdominal aortic aneurysm repair is not recommended in routine clinical practice outside of highly specialized centers, registries, or clinical trials [330].

ESVS/ESC III B (LoE 4 GoR C)

Postoperative management

Delayed recognition and treatment of complications is the primary determinant of perioperative mortality following both open and endovascular AAA repair. Therefore, patients undergoing open AAA repair should generally be admitted to the ICU for close monitoring and timely detection and management of complications. Local facilities and resources influence the selection of patients requiring ICU admission, but typically all patients undergoing open repair and those at high perioperative risk undergoing EVAR should be offered ICU monitoring. In addition, AAA repair should be performed in hospitals with continuous and immediate access to cardiac catheterization facilities [75]. Information on management strategies for patients after surgical AAA repair is presented in the relevant section.

3.2.4 Management of patients with ruptured AAA

Surgical interventions for symptomatic AAA

The optimal timing of surgery for a symptomatic unruptured AAA has not been definitively established. These aneurysms are thought to carry a higher risk of rupture than asymptomatic ones, while emergency repair under less favorable circumstances is associated with a higher risk of perioperative complications [331–334]. Management should include a short period of rapid assessment and optimization followed by delayed repair under optimal conditions [332]. Careful daily monitoring with strict blood pressure control is also essential while awaiting surgical repair.

• Patients with a symptomatic aneurysm and pain are recommended to be admitted to the intensive care unit for monitoring, hypotensive therapy, and necessary additional examinations [331–334].

ESVS/ESC I B (LEL 4, GRD C)

Comment: if pain increases, emergency surgery is indicated. In stable conditions, with pain relief and blood pressure reduction, surgery should be performed on an urgent basis (48–72 hours) by qualified surgeons. Emergency surgery is also indicated in patients who have predictors of rupture according to complex abdominal ultrasound and abdominal aorta CTA ("crescent" sign, fissuration of the mural thrombus, local partial tear of the aortic wall, "draping" aorta syndrome) [71].

Perioperative management

Optimized hypotension

Intensive restoration of circulating blood volume in patients with ruptured AAA leads to a pronounced increase in blood pressure, which may cause rebleeding [335]. The technique of so-called "permissive hypotension" was first proposed by E. Crawford [336]. In patients with ruptured AAA before surgery, circulating blood volume should be restored to the level of permissive hypotension (80–100 mm Hg) [335,337].

• In conscious patients with a ruptured abdominal aortic aneurysm, it is recommended to apply a permissive hypotension strategy, limiting intensive infusion-transfusion therapy [335,338–342].

ESVS/ESC I B (LEL 4, GRD C)

Comment: Most authors advise pursuing a permissive hypotension strategy while the patient remains conscious, with a target systolic blood pressure of 70–90 mm Hg [335,338–342].

Anesthetic management

Close cooperation between the anesthesiologist-intensivist and the surgeon is necessary, as vasodilation during anesthesia induction frequently leads to sudden arterial hypotension. Therefore, the surgical team must be ready for surgery, and the operative field should be prepared before anesthesia begins. This is important to minimize delays and rapidly arrest bleeding.

Unlike open surgery, one of the main advantages of EVAR for rAAA is the possibility of performing the intervention under local anesthesia combined, if necessary, with total intravenous anesthesia [343].

• Local anesthesia is recommended to be considered as the preferred anesthesia method for endovascular repair of a ruptured abdominal aortic aneurysm, if acceptable to the patient [343–345].

ESVS/ESC IIa B (LEL 4, GRD C)

Surgical tactics: open and endovascular vessel wall reconstruction

• In patients with a ruptured abdominal aortic aneurysm and suitable anatomy, endovascular repair is recommended as the method of choice. Depending on the patient's condition, anatomical features, local practice, team experience, and patient preferences, the surgical strategy may be modified by decision of the vascular team [346–348].

ESVS/ESC IIa B (LEL 1, GRD B)

• The feasibility of open repair or complex endovascular repair in patients with a juxtarenal abdominal aortic aneurysm is recommended to be considered after assessing the patient's condition, anatomical features, local practice, team experience, and patient preferences [349,350].

ESVS/ESC IIb C (Leveled Evidence 4, Grade of Recommendation C)

• During open repair of an abdominal aortic aneurysm, the choice between midline and transverse laparotomy or between transperitoneal and retroperitoneal approach is recommended to be made based on the surgeon's preference and patient risk factors [151,351].

ESVS/ESC IIa B (LEL 1, GRD A)

Comment: Proximal aortic control during open surgery is achieved either by clamping the infrarenal aorta, or by supraceliac or suprarenal clamping followed by moving the clamp to the infrarenal position as soon as possible. In some cases, proximal vascular anastomosis of the main artery can be formed without isolating the aneurysm wall under a supraceliac clamp.

Proximal aortic control can also be achieved using endovascular balloon occlusion of the aorta (BOA) as an alternative to conventional transverse aortic cross-clamping in hemodynamically unstable patients undergoing open surgery [176]. BOA can also be performed under direct visual control through the aortic wall during open surgery; compared to conventional aortic clamping, BOA resulted in lower intraoperative mortality, but not in-hospital mortality [113].

Vessel wall reconstruction. The simplest method should be chosen for vessel wall reconstruction during open surgery for ruptured AAA [177,323,352]. According to some experts, the use of a bifurcated stent-graft may be associated with increased perioperative mortality due to longer overall operative time.

Retroperitoneal hematoma. To prevent the development of abdominal compartment syndrome (ACS), the hematoma and blood clots should be removed whenever possible. Drain the retroperitoneal hematoma, lesser pelvis, and abdominal cavity. In case of intestinal paresis, the placement of a small bowel feeding tube is mandatory to prevent compartment syndrome and ensure enteral nutrition in the postoperative period [177,323,352].

Auxiliary interventions. Intraoperative autologous blood salvage (transfusion) to preserve circulating blood volume significantly reduces mortality during open surgery for ruptured AAA and in the early postoperative period [337,353]. This intervention should be included in the standard treatment protocol for such patients.

ESVS/ESC I B (LE 4, GR C)

Comments: A special protocol can ensure rapid and safe diagnostics, routine use of permissive hypotension in the preoperative period [359,360], simplify the use of EVAR [357], local anesthesia [356], as well as balloon occlusion of the aorta (BOA) if necessary [30]. It should be determined when and how to notify the endovascular surgery team and provide a suitable operating environment, preferably a hybrid operating room. Protocol-based management of life-threatening postoperative complications, particularly abdominal compartment syndrome (ACS), is also strongly requested [31,361].

Graft configuration and stent-graft selection***

During open surgery, the affected aortic segment is replaced with a Dacron or PTFE-based graft in a linear or bifurcated configuration, similarly to elective reconstructive surgery. Every effort should always be made to restore blood flow in at least one internal iliac artery if it is patent.

• Patients undergoing endovascular repair for a ruptured abdominal aortic aneurysm are recommended to have a bifurcated graft implanted rather than a linear one, if anatomically feasible [340,345,362–364].

ESVS/ESC IIa C (LEL 2, GRD B)

• In cases where imaging during endovascular repair of a ruptured abdominal aortic aneurysm is performed under permissive hypotension, it is recommended to oversize the abdominal aortic stent-graft*** by up to 30% [151,365].

ESVS/ESC IIa C (LE 4, GR C)

Comment: a crucial technical aspect of emergency EVAR is the degree of stent-graft*** oversizing under conditions of existing hypovolemia. The hemodynamic state of the patient at admission may influence this aspect, and to avoid intraoperative or late type Ia endoleak, oversizing by 30% is preferred when performing rAAA interventions where abdominal aorta CTA was performed under permissive hypotension [151].

Endovascular repair using balloon occlusion of the aorta in ruptured AAA

Approximately one-third of rAAA patients undergoing EVAR are in a hemodynamically unstable state, and every fourth patient presents with complete vascular collapse [364,366,367]. In such cases, immediate proximal aortic occlusion is required to stop bleeding by rapidly inflating an elastic balloon catheter for BOA. Continuous control using a balloon catheter prior to stent-graft*** implantation and occlusion of the rupture site is critical for survival. A meta-analysis of 39 studies showed that a total of 200 out of 1277 patients (14.1%) required BOA [368]. Mortality was significantly lower in studies with a higher rate of BOA use. This indicates that in hemodynamically unstable rAAA patients undergoing EVAR, BOA can improve outcomes.

• In hemodynamically unstable patients with ruptured abdominal aortic aneurysm undergoing open or endovascular repair, balloon aortic occlusion for proximal control is recommended to be considered depending on the patient's condition, anatomical features, local practice, team experience, and patient preference [151,339–341,343,364,367–371].

ESVS/ESC IIb C (Level of Evidence 2, Grade of Recommendation B)

Comment: Endovascular repair should be considered as the preferred intervention option in the majority of patients with rAAA [107,362,372,373].

Endovascular repair of ruptured abdominal aortic aneurysm with unfavorable anatomy

• In patients with ruptured juxta/pararenal abdominal aortic aneurysm, open repair or complex endovascular repair (using a fenestrated/branched stent-graft*** or parallel stent-graft techniques***) is recommended to be considered depending on the patient's condition, anatomical features, local practice, team experience, and patient preference [374,375].

ESVS/ESC IIb C (Leveled Evidence 4, Grade of Recommendation C)

• During open or endovascular repair of a ruptured abdominal aortic aneurysm in patients with suspected colonic ischemia, flexible sigmoidoscopy (rectosigmoidoscopy) is recommended to confirm the diagnosis [151,376–381].

ESVS/ESC IIa B (Level of Evidence 4, Grade of Recommendation C)

Abdominal compartment syndrome and intra-abdominal hypertension

Mortality in the event of abdominal compartment syndrome (ACS) following open and endovascular repair of rAAA is very high. Surgical removal of blood collections in the retroperitoneal space and retroperitoneal drainage during open repair of rAAA significantly reduces the incidence of ACS (3%) compared with endovascular repair (20%) [323,352,382]. The presence of a massive retroperitoneal hematoma due to rAAA can also be considered as an indication for open repair.

IAH is defined as a sustained or repeated pathological increase in intra-abdominal pressure (IAP) > 12 mmHg. ACS is defined as sustained IAP > 20 mmHg (with or without a decrease in abdominal perfusion pressure < 60 mmHg) accompanied by organ dysfunction/failure. Abdominal perfusion pressure is defined as the difference between mean arterial pressure and IAP [383].

In patients undergoing EVAR for rAAA, risk factors for ACS include (1) use of BOA; (2) severe coagulopathy; (3) need for massive blood transfusion; (4) preoperative loss of consciousness; (5) low preoperative blood pressure; and (6) emergency conversion from modular bifurcated stent-grafts to aorto-uni-iliac (AUI) device configuration [347]. Therefore, all such patients must be closely monitored so that treatment can be initiated at an early stage.

The algorithm for managing patients with IAH/ACS is presented in Figure PB-2. When IAH/ACS is suspected, conservative measures to reduce IAP (Table PB-3) should be attempted first.

If conservative measures are ineffective and full-blown ACS develops, abdominal decompression is indicated [362,383–385]. Ideally, a midline laparotomy is used for this.

Less invasive methods, such as translumbar abdominal decompression, have been described, but their safety has not been confirmed [362,386].

• When abdominal compartment syndrome develops after open or endovascular repair of a ruptured abdominal aortic aneurysm, decompressive laparotomy is recommended [340,387–389].

ESVS/ESC I B (LE 4, GR C)

• When treating abdominal compartment syndrome with open decompression after open or endovascular repair of a ruptured abdominal aortic aneurysm, the use of a negative pressure wound therapy system is recommended to be considered [387–389].

ESVS/ESC IIa C (LE 4, GR C)

3.2.5 Surgical treatment of juxtarenal abdominal aortic aneurysm

ESVS/ESC IIb C (LoE 5 GoR C)

• For complex endovascular repair of a juxtarenal abdominal aortic aneurysm, endovascular repair using a fenestrated stent-graft*** is recommended to be considered as the preferred treatment option in applicable cases [71,247,390].

ESVS/ESC IIa C (Leveled evidence 4, Grade of recommendation C)

Other adjuncts or new interventional tools that have the potential to expand the capabilities of endovascular treatment, including cases of rAAA with an atypical proximal neck, include off-the-shelf fenestrated stent-grafts***, modification of standard stent-grafts immediately prior to surgery to create notches and fenestrations, and the use of anchors*** to ensure proximal fixation.

• In patients with a juxtarenal abdominal aortic aneurysm, novel methods/concepts, including endovascular aneurysm sealing, the use of anchors*** for fixation, and *in situ* fenestration, are not recommended as first-line treatment [279,391].

ESVS/ESC III C (Level of Evidence 3, Grade of Recommendation C)

• For complex endovascular repair of a juxtarenal abdominal aortic aneurysm, the use of parallel stent-graft techniques*** is recommended to be considered as an alternative in emergency situations, or when modified (fenestrated) stent-grafts*** are indicated or unavailable, or as a temporary measure in an emergency, ideally with the implantation of no more than two chimney stent-grafts*** [391,392].

ESVS/ESC IIa C (Level of Evidence 4, Grade of Recommendation B)

Since the EVAS technique has already been used for ruptured infrarenal aneurysm [376], it may also be indicated for juxtarenal rAAA in combination with chimney stent-graft implantation [392]. The results of this technology in ruptured juxtarenal rAAA are awaited.

• In patients with a juxtarenal abdominal aortic aneurysm at acceptable surgical risk, a diameter of 5–5.5 cm is recommended to be used as the minimum threshold for considering elective repair [182].

ESVS/ESC I A (Level of Evidence 1, Grade of Recommendation A)

• In patients undergoing open repair for juxtarenal abdominal aortic aneurysm, a renal preservation strategy using cold saline renal perfusion is recommended [393,394].

ESVS/ESC IIa B (LEL 4, GRD C)

3.2.6 Surgical treatment of iliac artery aneurysm

Natural history and threshold diameter for surgical intervention

The reported growth rate of isolated iliac artery aneurysms (IIAA) is similar to that of AAAs—approximately 1–4 mm/year depending on aneurysm diameter [395,396].

According to published data, in most cases, rupture of IIAA occurs at a diameter greater than 5 cm and rarely at a diameter less than 4 cm [10,11,63,64,397–399].

The goal of surgical treatment for IIAA is to exclude the aneurysm from the circulation to prevent further growth and rupture. Before the introduction of endovascular repair in the early 1990s, open surgical repair (OSR) was the mainstay of IIAA treatment. The steady shift toward endovascular techniques since 2000 has been accompanied by a significant reduction in postoperative complications and mortality [400], as well as a decrease in complication rates and a shorter hospital stay [62,64,65,400].

• As a threshold value for elective repair of an isolated iliac artery aneurysm (common iliac artery, internal iliac artery, and external iliac artery, or a combination thereof), a diameter of ≥ 4.0 cm is recommended to be considered [10,11,63,64,151,397–399].

ESVS/ESC IIa C (Level of Evidence 4, Grade of Recommendation C)

• The repair technique for iliac artery aneurysms in patients with IIAA is recommended to be chosen taking into account individual patient characteristics and the nature of the lesion [151,401–405].

ESVS/ESC IIa B (Level of Evidence 4, Grade of Recommendation C)

Comment: OSR is usually performed under general anesthesia via a retroperitoneal or transabdominal approach. Depending on the extent of the aneurysmal segment, reconstruction is performed using a linear iliac graft or a bifurcated graft, including the infrarenal aorta, with or without revascularization of the internal iliac artery. A less invasive method in selected cases is iliac artery ligation with reperfusion of the contralateral femoral artery and/or internal iliac artery using a crossover femorofemoral bypass [10,406].

Due to the deep intrapelvic location, performing OSR for IIAA is associated with an increased risk of iatrogenic injuries to veins, ureters, or nerves, resulting in perioperative blood loss, complications, and increased mortality [64].

Endovascular repair

Endovascular treatment of IIA originally involved embolization of the IIA and stent-graft*** implantation in the segment extending from the CIA to the EIA. To ensure adequate proximal sealing during reconstructive surgery, involvement of the infrarenal aorta and contralateral iliac artery is sometimes required [60,64,67]. Thus, endovascular vessel wall reconstruction is more frequently associated with occlusion of the lumbar arteries and the inferior mesenteric artery, which must be taken into account. At the same time, when performing open surgery for an isolated IIA, the infrarenal aorta and contralateral iliac arteries can be left intact.

• In the management of patients with iliac artery aneurysm, endovascular reconstruction is recommended to be considered as a first-line treatment option [64,400,403,407].

ESVS/ESC IIb B (LOE 4 GoR C)

Comment: A significant advantage of endovascular reconstruction, especially in cases of ruptured isolated IIA, is the possibility of performing the procedure under local anesthesia. According to available data, conversion to open surgery is rarely required [398].

• When forming a non-infectious para-anastomotic aneurysm in the aortoiliac segment following abdominal aortic aneurysm reconstruction, endovascular reconstruction should be preferred [151,408].

ESVS/ESC IIa C (LOE 4 GoR C)

Pelvic circulation features

• When performing open surgical reconstruction and endovascular reconstruction for iliac artery aneurysm, it is recommended to preserve blood flow in at least one internal iliac artery [409].

ESVS/ESC I B (Leveled evidence 5, Grade of recommendation C)

Comment: the most common complication of endovascular treatment of IIA is buttock claudication, the reported incidence of which reaches 28% [62,64–67]. Therefore, preserving blood flow in at least one IIA is indicated, provided this does not compromise the primary treatment goal—excluding the aneurysm from the circulation. Due to the current availability of branched stent-grafts***, blood flow in the IIA can be preserved in most cases, which helps reduce the incidence of buttock claudication in the treatment of aortoiliac AAA and IIA involving the IIA [403,410].

• In patients with an indication for endovascular embolization or ligation of the internal iliac artery, it is recommended to perform endovascular occlusion of the proximal main vessel trunk (IIA ostium), if technically feasible, to preserve distal collateral circulation in the pelvis [409].

ESVS/ESC I C (LOE 5 GoR C)

Comment: in cases where a stent-graft*** covers a long segment of the aorta with occlusion of segmental arteries, preserving blood flow in the IIA is crucial for the prevention of spinal cord ischemia, as collateral blood supply to the spinal cord is provided at this level [411].

• During endovascular repair of an abdominal aortic aneurysm, routine prophylactic embolization of the inferior mesenteric artery and lumbar arteries, as well as non-selective endovascular embolization of the aneurysmal sac, are not indicated [151,412–415].

ESVS/ESC III B (LOE 2 GoR A)

3.2.7 Surgical treatment of mycotic abdominal aortic aneurysm

Patients with a mycotic abdominal aortic aneurysm have an increased risk of aneurysm rupture and other complications; therefore, treatment must be performed regardless of the lesion diameter. Similar treatment outcomes for infected tissue, regardless of the chosen strategy, do not allow for definitive conclusions regarding the preferred intervention option. According to the Swedish registry data, open in situ treatment and endovascular intervention in patients with MAA do not differ in terms of long-term survival and infection-related mortality [8,23].

Open reconstruction

Early diagnosis, prompt administration of systemic antibacterial drugs, and timely surgical treatment are crucial for improving early outcomes. Despite the lack of evidence, open surgery is considered the gold standard for the radical treatment of MAA.

Open surgery includes aneurysmectomy with grafting and branchplasty, extensive local surgical debridement, and revascularization using extra-anatomic aortic bypass or in situ reconstruction. Options for using in situ vascular grafts preferably include autologous vein (formation of a neo-aortoiliac system from the femoral or great saphenous vein), cryopreserved arteries, or a vascular xenograft, depending on the surgeon's preference [139,416–418].

Material obtained during the procedure must be sent for microbiological analysis, extensive debridement of the wound or infected tissue must be performed, and the infectious process must be isolated from the prosthesis using the omentum.

• Surgical methods used for MAA are recommended to be considered taking into account the patient's condition and the team's experience, with endovascular vessel wall reconstruction being an acceptable alternative to open reconstruction [22,26,416,419].

ESVS/ESC IIa B (LEL 4, GRD C)

Endovascular repair

Over the past 15 years, MAAs have been increasingly and successfully treated with endovascular methods. EVAR for MAA (EVAR-MAA) was initially viewed with skepticism due to serious concerns regarding the preservation of infected tissue within the treatment zone, including the aneurysm itself, and the risk of recurrent/persistent infection. On the other hand, EVAR-MAA is a less invasive alternative to standard open surgery for MAA, allowing for the treatment of frail and comorbid patients with complex aneurysm anatomy while avoiding major surgical trauma (aortic clamping, heparinization, and massive blood transfusion).

• Following reconstructive surgery for MAA, long-term antibiotic therapy (6–12 months or lifelong) and subsequent follow-up are recommended [8,134,416].

ESVS/ESC IIa B (LEL 4, GRD C)

Thus, MAA is a rare and life-threatening condition. Early detection and antibiotic therapy followed by surgical intervention play a central role in the management of this aneurysm. Results from the largest and most recent studies with long-term follow-up indicate that EVAR-MAA may offer short-term advantages over open reconstruction without any late disadvantages. However, due to the rarity of MAA, robust evidence is lacking, making it difficult to formulate strong recommendations.

• Reconstruction for MAA is recommended regardless of aneurysm size [8,22,420].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

• Patients with abdominal aortic MAA are recommended to be referred to major vascular surgery centers, as their management requires a multidisciplinary approach [151].

ESVS/ESC I C (LOE 5 GoR C)

3.2.8 Surgical treatment of inflammatory abdominal aortic aneurysm

The lifelong risk of rupture is low < 5% [12]. The same diameter threshold for reconstructive intervention is used as in standard degenerative AAA. In rare cases, patients with persistent clinical symptoms despite medical therapy may be indicated for invasive treatment to control the inflammatory process [421]. In cases of pronounced preoperative hydronephrosis, Double-J ureteral stents may be placed in the urinary tract.

Open surgery is complicated by the presence of inflammatory adhesions to the wall of the duodenum, left renal vein, inferior vena cava, and ureters. A transperitoneal approach with limited dissection of the proximal neck, leaving the duodenum attached to the thickened wall, and proximal aortic clamping away from the thickened sections of the aneurysm wall helps reduce surgical trauma to adjacent organs and associated surgical mortality (6–11%) [150,421].

Endovascular treatment is characterized by lower overall one-year mortality postoperatively. However, according to a 2009 systematic review, aneurysm-related mortality is similar regardless of the intervention type. At the same time, the open surgery group showed a significantly higher rate of postoperative reduction in hydronephrosis severity. No significant differences were established in terms of 30-day mortality and the rate of reduction in periaortic tissue inflammation. For the reasons stated above, in most cases, endovascular intervention should be considered the preferred treatment option for iAAA, whereas open surgery is indicated for pronounced hydronephrosis and a low risk of mortality and complications [150,422].

• As the method of choice for the surgical treatment of iAAA, with an aneurysm diameter threshold of 5.5 cm and suitable anatomy in patients with inflammatory abdominal aortic aneurysm, endovascular vessel wall reconstruction is recommended [29,71,150,423–425].

ESVS/ESC IIa C (LE 4, GR C)

Hydronephrosis and para-aortic fibrosis may persist and even progress despite open surgery or EVAR [150]. Therefore, to reduce or stabilize para-aortic inflammation, continued immunosuppressive therapy [144,148] and careful postoperative monitoring are indicated, although urinary tract stenting, nephropyelostomy, or open surgery may sometimes be required.

3.2.9 Surgical treatment of aortic dissection, saccular aneurysm, penetrating aortic ulcer, intramural hematoma, and pseudoaneurysm

Complicated penetrating aortic ulcer (PAU) is defined as a combination of extra-aortic hematoma (pseudoaneurysm), embolic symptoms, pain attacks, PAU with initial dimensions of > 20 mm in width or > 10 mm in depth, or an increase in the total diameter of the abdominal aorta [426,427]. Similarly, complicated IMH/PAU means the presence of pain attacks, growth of IMH, para-aortic hematoma, intimal tear, or malperfusion.

• In patients with complicated penetrating aortic ulcer, dissection, intramural hematoma, and abdominal aortic pseudoaneurysm, reconstructive intervention is recommended [24,46,71,152].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comment: in complicated PAU/IMH/PAU, invasive treatment is indicated, similar to that for symptomatic/ruptured AAA associated with concomitant aneurysms, even for lesions < 5 cm in diameter [21], although some specialists recommend an aggressive approach when the total aortic diameter is > 3 cm [34].

• In patients with complicated penetrating aortic ulcer, dissection, intramural hematoma, or abdominal aortic pseudoaneurysm, endovascular vessel wall reconstruction is recommended to be considered as the method of choice [16,18–20,153,426,427].

ESVS/ESC IIa C (LoE 3 GoR B)

Comment: due to their focal nature, these pathological changes are ideally suited for endovascular vessel wall reconstruction using abdominal aortic stent-grafts***. Such an intervention is characterized by a high technical success rate in complicated cases, but may be associated with high in-hospital mortality (10%) due to the debilitated condition of patients with this pathology [426,427].

• In saccular abdominal aortic aneurysms, early treatment with a lower diameter threshold for elective reconstructive intervention than in standard fusiform abdominal aortic aneurysms is recommended to be considered [21].

ESVS/ESC IIb C (Leveled Evidence 4, Grade of Recommendation C)

3.2.10 Surgical treatment of AAA in hereditary connective tissue disorders

Patient management strategies, including follow-up imaging (CTA/MRA (single region)/duplex ultrasound of the aorta), medical therapy, or surgical intervention in an individual patient, should be discussed within a multidisciplinary aortic team.

An individualized approach is of paramount importance because the risk of rupture is higher at smaller aortic diameters, for example in Loeys-Dietz syndrome (TGFβR1, 2) and aneurysm-osteoarthritis syndrome (SMAD 3), than in patients with Marfan syndrome (FBN1-fibrillin-1), and surgical reconstruction is more challenging in EDS due to an increased susceptibility to arterial wall disruption than in Marfan syndrome.

Extremely rarely, isolated AAA can be a manifestation of connective tissue disorders. Only a few such cases have been described in the literature [428–431]. Endovascular treatment is not indicated for this etiology of AAA. The application of radial force required for the deployment of stent-grafts*** is contraindicated in patients with connective tissue disorders due to increased fragility of the aortic walls [432,433].

This can lead to type I endoleak and stent-graft*** migration. In patients with connective tissue disorders, endovascular treatment can be performed as an emergency bridging intervention to save life in case of blood loss caused by aneurysm rupture. However, in routine clinical practice, ideal conditions for the intervention are rarely met. If the patient has previously undergone surgical treatment or has multiple comorbidities or other clinical circumstances that increase the risks of open surgery, endovascular treatment is the optimal strategy. Nevertheless, open surgery should be considered the primary intervention option in the treatment of AAA in the vast majority of patients with connective tissue disorders.

• In abdominal aortic aneurysms in patients with a genetic predisposition, the aneurysm diameter threshold for reconstructive intervention is determined individually, depending on the results of genetic testing and anatomical features [151].

ESVS/ESC I C (Leveled evidence 5, Grade of recommendation C)

• For the management of patients with aortic pathology when a primary genetic cause is suspected, it is recommended to refer them to a highly specialized center with a multidisciplinary aortic team [434,435].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comment: a recent international consensus report on the diagnosis, natural history, and management of EDS concluded that unrestricted ruptures or clinically unstable aneurysms (prior to rupture), or false aneurysms often require appropriate intervention. Depending on the localization, endovascular treatment (embolization of the bleeding artery) or open surgery (aorta and iliac vessels) may be indicated, although invasive procedures can provoke further complications [436].

Ideally, the management of patients with EDS should, whenever possible, be concentrated in centers of excellence [436]. The European Reference Network on Rare Multisystemic Vascular Diseases (http://vascern.eu/) provides detailed information on the management of this rare disease.

• In young patients with suspected connective tissue disorders and an abdominal aortic aneurysm, open surgery is recommended as the method of choice [435].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

3.3 Other Treatment

Palliative care

Various scoring systems and algorithms have been tested to predict the futility of open or endovascular surgical intervention in rAAA and to select patients for palliative care, but to date none of them has proven to be accurate [437]. The decision to withhold AAA surgery in severely ill patients, those with stage IV malignancies, or in agonal states must be made by a medical board involving the chief surgeon and chief anesthesiologist-resuscitologist of the medical organization where the patient is located, or their deputies.

ESVS/ESC III C (LoE 3 GoR B)

Concomitant malignancies

The reported incidence of concomitant malignancies and AAA is 5.4–6.7% [447–450].

As a prophylactic intervention, AAA repair is advisable only if the lifetime risk of rupture outweighs the risk associated with treatment in patients with a reasonable life expectancy. Thus, the prognosis of the concomitant malignancy is central to the decision-making process alongside other comorbidities (age, physiological status) and patient preferences. Other considerations include the presumed increased risk of AAA rupture after abdominal cancer surgery [451,452], compared with a significant delay in cancer treatment if AAA is treated first with open surgical repair, as well as the risk of graft infection.

• In patients with a concomitant malignancy, it is recommended to consider prolonged prophylactic administration of low molecular weight heparins for up to four weeks after abdominal aortic aneurysm repair [71,447,453,454].

ESVS/ESC IIa C (LoE 3 GoR B)

Comment: there is a likelihood of an increased risk of deep vein thrombosis and pulmonary embolism, as well as limb thrombosis after EVAR (up to 7%), possibly due to hypercoagulability, thrombophilia, paraneoplastic syndrome, chemotherapy, and the lithotomy position [447,449,455–458]. In patients with a concomitant malignancy, the possibility of prolonged prophylactic administration of low molecular weight heparins for up to four weeks after EVAR should be considered [453,454].

4. Medical Rehabilitation and Sanatorium-Resort Treatment

Enhanced Recovery After Surgery program

Enhanced recovery after surgery in open AAA repair.

• To accelerate postoperative recovery in surgical patients operated on for abdominal aortic aneurysm/abdominal and peripheral artery aneurysm by reducing the surgical stress response, it is recommended to use early or enhanced recovery after surgery (ERAS / FAST-TRACK Surgery) programs [459–461].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comment: A limited number of studies have evaluated ERAS protocols in open AAA reconstruction, noting a reduction in hospital stay and fewer pulmonary complications [460,461].

ERAS relies on a comprehensive multidisciplinary approach, including thorough preoperative counseling for patient psychological preparation, the use of epidural anesthesia and minimally invasive surgical access, optimal pain management with minimized side effects, early postoperative mobilization and oral feeding, as well as the avoidance (or early removal) of all types of drains and upper urinary tract catheters [459].

FAST-TRACK Surgery. Enhanced recovery or fast-track surgery has been gaining increasing support in recent years. The strategy is based on reducing surgical stress and consists of:

• Oral and written patient information;

• No bowel preparation;

• Reduction of preoperative fasting time;

• No premedication;

• Prevention of thromboembolic complications;

• Antimicrobial prophylaxis;

• Combined anesthesia;

• Mini-incisions;

• Prevention of intraoperative hypothermia;

• Prevention and treatment of postoperative nausea and vomiting syndrome;

• Reduction of postoperative infusion volume;

• Early patient mobilization.

All this allows for the earliest possible patient activation and shortens the length of hospital stay.

5. Prevention and Dispensary Observation

Preadneurysmal aortic dilatation

ESVS/ESC I B (LoE 2, GoR B)

• For the surveillance of patients with AAA, duplex ultrasound of the abdominal aorta is recommended with the following frequency: once every three years for aneurysms with a diameter of 3–3.9 cm, once a year for aneurysms with a diameter of 4.0–4.9 cm, and once every 3–6 months for aneurysms ≥ 5.0 cm [463].

ESVS/ESC I B (LoE 2, GoR B)

Comment: for small aneurysms (3–3.9 cm), a surveillance interval of once every three years is safe (though a longer interval may also be considered); for aneurysms with a diameter of 4.0–4.9 cm, annual surveillance is safe. The projected surveillance interval, extrapolated from AAA surveillance intervals, may be once every three years for iliac artery aneurysms with a diameter of 2.0–2.9 cm and once a year for a diameter of 3.0–3.4 cm.

• For iliac artery aneurysms (common iliac artery, internal iliac artery, external iliac artery, or a combination thereof), it is recommended to perform follow-up with duplex scanning of the abdominal aorta, iliac, and common femoral arteries once every 3 years for aneurysms with a diameter of 20-24 mm, once every 2 years for aneurysms with a diameter of 25-29 mm, and once a year for aneurysms with a diameter of ≥ 30 mm [151, 464].

ESVS/ESC IIa C (LoE LoR C)

Monitoring the aneurysm growth rate

• Patients with AAA are recommended to stop smoking (to reduce the growth rate of abdominal aortic aneurysm and the risk of its rupture) and to seek smoking cessation counseling [50, 465].

ESVS/ESC I B (LEL 2, GRD B)

• Patients with AAA who regularly smoke tobacco or use alternative nicotine delivery systems (ANDS) are recommended complete nicotine cessation at every visit with their attending physician [50, 465].

ESVS/ESC I B (LEL 2, GRD B)

• In patients with CVD who regularly smoke tobacco, complete transition to non-combustible nicotine-containing products is recommended as a risk-reduction strategy and a pathway to smoking cessation, although the risk of long-term use and unknown long-term safety require follow-up [50, 465].

ESVS/ESC I B (LoE 2 LoR B)

• Patients with CVD are recommended to avoid passive smoking to reduce the risk of cardiovascular events [50, 465].

ESVS/ESC I B (LoE 2 LoR B)

Comment: all observational studies indicate that current smoking is associated with an increased AAA growth rate, and smoking cessation is likely associated with a reduction in the growth rate of approximately 20%, as well as a twofold decrease in the risk of aneurysm rupture [50]. Many randomized trials have shown that smoking cessation is most effective when combined with pharmacotherapy for nicotine dependence and smoking cessation counseling [465]. Patients with diabetes mellitus also have a lower AAA growth rate compared to patients without diabetes mellitus, which, according to recent hypotheses, is associated with the use of metformin** (ATC: A10BA02) prescribed for the treatment of type 2 diabetes mellitus [50, 466].

• For uncomplicated penetrating aortic ulcer, dissection, or intramural hematoma of the abdominal aorta, it is recommended to perform follow-up imaging using CTA of the abdominal aorta or MR angiography of the aorta (one region) [46, 152].

ESVS/ESC I C (Level of Evidence 4, Grade of Recommendation C)

Comment: Given that almost nothing is known about its natural history, dynamic follow-up using CTA of the abdominal aorta or MR angiography of the aorta (one region) is justified [426, 427]. Assessment of the ulcer includes measuring the maximum aortic diameter at the level of the ulcer localization, the depth of the ulcer, and the length of the intimal defect (width) at the level of the ulcer localization. The growth rate of a PAU in the abdominal region is approximately 3 mm/year.

Cardiovascular risk reduction strategy

• All patients with abdominal aortic aneurysm are recommended to consider healthy lifestyle strategies, including physical exercise and a healthy diet [467–469].

ESVS/ESC IIa B (LE 5, GR C)

• All patients with abdominal aortic aneurysm are recommended to control blood pressure (first-line drugs are ACE inhibitors and beta-blockers), use statins and antithrombotic agents [131, 193, 468, 469].

ESVS/ESC IIa B (LEL 4, GRD C)

Comment: Patients with AAA are at high risk of future cardiovascular events. A systematic review showed that in patients with small AAAs, the annual risk of cardiovascular death was 3.0% (95% CI 1.7-4.3) [470]. According to the European Guidelines on cardiovascular disease prevention, all patients with symptomatic peripheral artery disease should receive antithrombotic therapy in the absence of contraindications, lipid-lowering agents if low-density lipoprotein (LDL) cholesterol is > 2.5 mmol/L (> 97 mg/dL), and antihypertensive drugs if systolic BP is > 140 mmHg [131, 467, 468]. The UK Heart Protection Study showed that in patients with peripheral artery disease, taking simvastatin** 40 mg (ATC: C10AA01) once daily reduced the incidence of the first major adverse cardiovascular event by 22% compared to patients randomized to placebo [471].

Features of postoperative follow-up after EVAR (monitoring)

Due to the risk of graft-related complications and rupture after EVAR, regular imaging surveillance as part of follow-up is considered mandatory.

• In the early postoperative period, all AAA patients after open reconstruction and high-risk patients after endovascular reconstruction are recommended to be monitored in the ICU or step-down unit [151].

ESVS/ESC I C (LOE 5 GoR C)

RCC I C (LoE 5 GoR C)

RCC I C (LoE 5 GoR C)

ESC I C (LoE C, GoR 5)

Imaging studies after EVAR

The list of imaging modalities, along with their advantages and disadvantages, is presented in Table PB-4. Typically, CTA of the abdominal aorta and/or duplex ultrasound of the aorta form the basis of follow-up imaging after EVAR [472].

Plain abdominal radiography

Traditionally, plain anteroposterior and lateral abdominal radiography has been used during follow-up to detect stent-graft*** fractures and migration [473]. However, this imaging modality is extremely limited in detecting potential EVAR complications and, therefore, is not suitable as the sole imaging method for follow-up.

RCS IIb C (LEL 5, GRD C)

Multislice computed tomography

CT angiography (CTA) allows for the evaluation and detection of most EVAR complications (Table PB-4).

• Patients after EVAR are recommended to undergo CTA of the abdominal aorta (A06.12.052) to detect potential complications [474].

RSC I B (LOC 1, LOR B)

Comments: Current instructions for use for stent-grafts*** include recommendations regarding regular follow-up with up to five CT scans within the first year after surgery [475,476].

Magnetic resonance (MR) angiography of the aorta

MR angiography of the aorta (single region) can be used in selected patients for follow-up after EVAR. Aneurysm diameter measurements using MR angiography of the aorta (single region) are comparable to measurements performed using abdominal aortic CTA [477]. A systematic review of data from eleven studies compared the results of MR angiography of the aorta (single region) and abdominal aortic CTA after EVAR. MR angiography of the aorta (single region) proved to be more sensitive in detecting type II endoleaks [478]. Thus, MR angiography of the aorta (single region) may play a specific role in imaging patients with an increasing aneurysm sac size after EVAR when abdominal aortic CTA results are negative or inconclusive. The use of stent-grafts*** made of ferromagnetic materials results in significant artifacts that hinder image analysis.

• In patients after EVAR, as part of follow-up and to rule out complications, it is recommended to consider the need for MR angiography of the aorta (single region) [477].

RSC IIb B (LOC 3, LOR B)

Duplex ultrasound scanning of the aorta

Duplex ultrasound scanning (DUSS) of the aorta provides the ability for repeated and reliable measurement of the maximum aneurysm diameter at low cost and without exposing the patient to ionizing radiation or nephrotoxic contrast media. Diameter measurements using DUSS of the aorta cannot be directly compared with measurements from abdominal aortic CTA [479]; therefore, evaluating the dynamics of aneurysm sac size changes after EVAR requires serial imaging using the same modality.

• In selected cases, one year after endovascular repair of a complex abdominal aortic aneurysm, as an alternative to follow-up using abdominal aortic CTA, it is recommended to consider follow-up using DUSS of the aorta [151,480,481].

ESVS/ESC IIb C (Leveled Evidence 4, Grade of Recommendation C)

Follow-up algorithm after EVAR

• Following endovascular abdominal aortic aneurysm repair, regardless of the initial risk group, it is recommended to perform an early (within 30 days) postoperative follow-up including an imaging study (comprehensive abdominal ultrasound or CT angiography) of the endovascular abdominal aortic stent-graft*** to assess for endoleaks, component overlap, sealing zone length, and aneurysm sac size dynamics [71,151,482–484].

ESVS/ESC I B (LEL 2, GRD B)

Comment: she modern follow-up algorithm after EVAR should include imaging in the early postoperative period to detect endoleak and assess apposition of the endovascular abdominal aortic stent-graft*** to the arterial wall [71].

Following this, patients can be stratified into three groups based on the initial imaging results (Figure 9):

• low-risk group (no endoleak, anatomy matches IFU description, adequate proximal and distal overlap and seal of the endovascular abdominal aortic stent-graft*** to the arterial wall ≥ 10 mm) may be considered for limited follow-up with delayed imaging within five years after reconstruction;

• intermediate-risk group (adequate overlap and seal, but presence of type II endoleak). Patients in this group undergo follow-up to assess aneurysm sac enlargement or shrinkage. Patients with aneurysm sac shrinkage ≥ 1 cm in the presence of a type II endoleak may be categorized as low risk of failure with restricted follow-up, similar to the low-risk group;

• high-risk group (presence of type I or type III endoleak, inadequate overlap or seal < 10 mm). In such patients, the need for reintervention should be evaluated based on imaging results. Reintervention is recommended for type I or type III endoleak or kinking of the endovascular abdominal aortic stent-graft***. In patients with inadequate overlap or seal < 10 mm and no signs of endoleak, repeat imaging, primarily CTA, is recommended to accurately assess overlap, seal, endoleak, and aneurysm sac enlargement during follow-up.

In patients at low risk of endovascular aortic repair failure after the first postoperative abdominal CTA, stratification for less frequent imaging during follow-up is recommended in accordance with the algorithm below (Figure App-3) [482,483,485,486].

ESVS/ESC IIb C (LoE 4 GoR C)

This follow-up schedule after EVAR is indicated when standard devices are used. Complex procedures, notably EVAR using fenestrated/branched stent-grafts***, patients undergoing reconstruction using parallel stent-grafts*** such as "chimney" grafts, or new device systems designed for EVAR based on non-standard technology, require an individualized follow-up approach based on the device used, the reconstruction, and the estimated risk of late failure.

• Patients undergoing endovascular vessel wall reconstruction for juxtarenal abdominal aortic aneurysm are recommended a long-term follow-up program including annual aortic computed tomography angiography [71,391].

ESVS/ESC I C (Leveled evidence 5, Grade of recommendation C)

Although all AAA patients should receive antithrombotic therapy, many large trials on complex endovascular reconstruction did not specify the postoperative anticoagulation regimen [391,487,488], whereas other studies used ASA** (ATC: B01AC06) 75–100 mg 1 tablet once daily orally or DAPT [392].

• All patients undergoing open or endovascular treatment for a ruptured abdominal aortic aneurysm are recommended intra-abdominal pressure monitoring for early diagnosis and management of intra-abdominal hypertension/abdominal compartment syndrome [362,383,384,387,388].

ESVS/ESC I B (Leveled evidence 5, Grade of recommendation C)

6. Organization of Medical Care

Medical care for patients with abdominal aortic aneurysm (AAA) may be provided in the following settings:

- on an outpatient basis (under conditions not providing for round-the-clock medical observation and treatment);

- in a day hospital (in conditions providing medical observation and treatment during the day, not requiring round-the-clock medical observation and treatment);

- on an inpatient basis (under conditions providing for round-the-clock medical observation and treatment).

Medical care for patients with AAA is provided in the following forms:

- primary health care;

- emergency medical care, including specialized emergency medical care;

- specialized medical care, including high-tech medical care.

Primary health care includes measures for AAA screening, diagnosis, follow-up, medical rehabilitation, and promotion of a healthy lifestyle

Primary health care for patients with AAA includes:

1) primary pre-medical health care;

2) primary medical health care;

3) primary specialized health care.

Primary pre-medical health care is provided on an outpatient basis by mid-level medical personnel of feldsher health posts, feldsher-midwifery stations, medical outpatient clinics, health posts, polyclinics, polyclinic departments of medical organizations, medical prevention departments (offices), and health centers.

Primary physician-delivered health care is provided by a district general practitioner or general practitioner (family physician) in an outpatient setting. Upon detecting signs of AAA, the patient is referred to a relevant specialist for primary specialized health care.

A key feature of managing patients with AAA is the need for regular follow-up examinations. When technically feasible, diagnostic screenings, including imaging modalities, should be performed in an outpatient setting with subsequent interpretation of the obtained data by dedicated vascular surgeons.

Primary specialized health care is provided to patients with AAA by general surgeons and cardiovascular surgeons. Diagnostic examinations involve ultrasound diagnostics specialists, functional diagnostics physicians, and radiologists. If medical care cannot be provided within the framework of primary health care and clinical indications are present, the patient is referred to a medical organization providing specialized medical care.

Emergency, including specialized, medical care for patients with AAA requiring urgent medical intervention is provided by paramedic general-profile mobile emergency teams, physician general-profile mobile emergency teams, specialized anesthesiology and resuscitation mobile emergency teams, and emergency consultative mobile teams in accordance with the Procedure for the Provision of Emergency, Including Specialized, Medical Care approved by Order of the Ministry of Health of the Russian Federation No. 388n dated June 20, 2013. Emergency, including specialized, medical care is provided to patients with AAA in the event of life-threatening conditions, such as AAA rupture, various forms of complicated AAA, symptomatic aneurysms, as well as aortic enlargement exceeding 9 cm. When providing emergency medical care, medical evacuation is carried out when necessary, which includes air-medical evacuation and transportation by other types of vehicles.

The emergency medical team delivers patients with life-threatening conditions to medical organizations providing round-the-clock medical care in the field of cardiovascular surgery or general surgery.

If clinically indicated and after life-threatening conditions have been resolved, patients are transferred to a cardiovascular surgery, vascular surgery, or general surgery department of a medical organization to receive specialized medical care.

Specialized, including high-tech, medical care is provided in an inpatient setting by cardiovascular surgeons, and in some cases by endovascular surgeons, within inpatient facilities as well as surgical departments incorporating vascular beds; it includes diagnosis, treatment requiring special methods and complex medical technologies, and medical rehabilitation. When clinically indicated, treatment is carried out involving medical specialists in the specialties provided for by the Nomenclature of Specialties of Specialists with Higher and Postgraduate Medical and Pharmaceutical Education in the Healthcare Sector of the Russian Federation, approved by Order of the Ministry of Health of the Russian Federation No. 700n dated October 7, 2015, specifically: ultrasound diagnostics physicians, functional diagnostics physicians, radiologists, radiotherapists, anesthesiologists-resuscitators, and medical rehabilitation physicians.

Elective medical care is provided to patients with AAA when the disease stage is not life-threatening, does not require emergency or urgent care, and postponing care for a certain period will not entail worsening of the condition or threaten the patient's life and health.

Indications for elective hospitalization of patients with AAA in a hospital are:

- surgical treatment of AAA;

- surgical treatment of conditions and complications following open and endovascular interventions for AAA.

Not an indication for hospitalization:

- performance of periodic diagnostic screenings for AAA, provided they can be technically performed on an outpatient basis.

The provision of medical care in a medical organization providing specialized medical care is carried out based on clinical indications upon independent presentation by the patient, by referral from a paramedic, district general practitioner, general practitioner (family physician), general surgeon, or cardiovascular surgeon of a medical organization providing primary health care, as well as upon delivery of the patient by an emergency medical team.

Indications for emergency hospitalization of patients with AAA in a hospital are:

- suspected aneurysm rupture;

- symptomatic aneurysm, as well as clinical situations in which, in the presence of an AAA, it is not possible to rule out a correlation between the pain syndrome and aortic enlargement;

- other complicated forms of AAA (aortic dissection, saccular aneurysm, penetrating aortic ulcer, intramural hematoma, pseudoaneurysm, impending rupture, aorto-organ or aorto-venous fistulas);

- giant aneurysms (greater than 9 cm in diameter);

- aneurysm thrombosis, peripheral arterial thromboembolism originating from the aneurysm lumen.

The following strategies are possible for patients with rAAA:

• stable patients with rAAA should be hospitalized in a medical facility with a round-the-clock vascular unit;

• patients with rAAA in extremely severe condition when delivery to a specialized hospital is not feasible are recommended to be transported to the nearest surgical hospital with the subsequent dispatch of a team of cardiovascular surgeons via air-medical evacuation [489–494].

The recommended composition of a mobile vascular team from a specialized institution for rAAA: at least two endovascular specialists and one anesthesiologist-resuscitator of the vascular team [29,71,490].

Criteria for discharge from the hospital:

- completed surgical treatment of AAA, conditions, or complications following open and endovascular interventions for AAA.

Patients who have undergone surgical interventions for various forms of AAA are referred, when clinically indicated, for rehabilitation measures to specialized medical and sanatorium-resort organizations.

Criteria for Evaluating the Quality of Medical Care

Quality assessment criteria for primary specialized health care provided to adults with abdominal aortic aneurysm without mention of rupture (ICD-10 code: I71.4)

Quality assessment criteria for specialized medical care provided to adults with abdominal aortic aneurysm without mention of rupture (ICD-10 code: I71.4)

Quality assessment criteria for primary health care provided to adults with ruptured abdominal aortic aneurysm (ICD-10 code: I71.3)

Quality assessment criteria for specialized medical care provided to adults with ruptured abdominal aortic aneurysm (ICD-10 code: I71.3)

References

Appendix A1. Working Group Composition

All members of the Working Group confirmed the absence of financial support or other conflicts of interest in the preparation of these guidelines.

Principal Investigator: Svetlikkov Alexey Vladimirovich, MD, PhD, Professor, Department of Hospital Surgery, Saint Petersburg State University, Russian Society of Angiologists and Vascular Surgeons (Saint Petersburg)

Executive Secretary: Sukhoruchkin Vladislav Aleksandrovich. Russian Society of Angiologists and Vascular Surgeons (Saint Petersburg)

Irtyuga Olga Borisovna, MD, PhD, Head of the Research Laboratory of Congenital and Acquired Heart Defects, Professor, Department of Cardiology, Almazov National Medical Research Centre (Saint Petersburg), Russian Society of Cardiology (RSC)

Abugov Sergey Alexandrovich, MD, PhD, Professor, Corresponding Member of the Russian Academy of Sciences, Russian Scientific Society of Endovascular Diagnostics and Treatment. Russian Society of Angiologists and Vascular Surgeons

Akchurin Renat Suleymanovich, Academician of the Russian Academy of Sciences, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Alekseeva Daria Vladimirovna, Head of the Department of Diagnostic Radiology No. 1, Assistant Professor, Department of Diagnostic Radiology and Medical Imaging, Almazov National Medical Research Centre of the Russian Ministry of Health (Saint Petersburg), Russian Society of Cardiology (RSC), Russian Society of Roentgenologists and Radiologists (RSRR)

Alekyan Bagrat Gegamovich, Academician of the Russian Academy of Sciences, MD, PhD, Professor, Russian Scientific Society of Endovascular Diagnostics and Treatment

Andreychuk Konstantin Anatolyevich, PhD, Associate Professor, Association of Cardiovascular Surgeons of Russia, Russian Society of Angiologists and Vascular Surgeons,

Arakelyan Valeriy Sergeevich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Babakekhyan Meri Vartanovna, Junior Research Fellow, Research Laboratory of Congenital and Acquired Heart Defects, Assistant Professor, Department of Cardiology, Almazov National Medical Research Centre (Saint Petersburg), Russian Society of Cardiology (RSC)

Bazylev Vladlen Vladlenovich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Balakhonova Tatyana Valentinovna, MD, PhD, Member of the Executive Committee of the Russian Association of Ultrasound Diagnostics in Medicine (RASUDM), Presidium Board Member of the National Atherosclerosis Society (NAS), Russian Society of Cardiology (RSC), European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB), World Federation for Ultrasound in Medicine and Biology (WFUMB), European Society of Cardiology (ESC)

Basek Ilona Vladimirovna, PhD, Head of the Diagnostic Radiology Department, Associate Professor, Department of Diagnostic Radiology and Medical Imaging (Saint Petersburg), RSC, RSRR

Belov Yury Vladimirovich, Academician of the Russian Academy of Sciences, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Bredikhin Roman Alexandrovich, MD, PhD, Russian Society of Angiologists and Vascular Surgeons,

Vanyurkin Almaz Gafurovich, Researcher, Research Department of Vascular and Interventional Surgery, Cardiovascular Surgeon (Saint Petersburg), RSC, ACSR

Vachev Alexey Nikolaevich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Vinogradov Roman Alexandrovich, MD, PhD, Associate Professor, Association of Cardiovascular Surgeons of Russia, Russian Society of Angiologists and Vascular Surgeons,

Gavrilenko Alexander Vasilyevich, Academician of the Russian Academy of Sciences, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Golovyuk Alexander Leonidovich, PhD, Russian Society of Angiologists and Vascular Surgeons

Gurevich Viktor Savelyevich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons, National Atherosclerosis Society

Enkina Tatyana Nikolaevna, PhD, Russian Association of Ultrasound Diagnostics in Medicine (RASUDM)

Ezhov Marat Vladislavovich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons, National Atherosclerosis Society

Zatevakhin Igor Ivanovich, Academician of the Russian Academy of Sciences, MD, PhD, Professor, President of the Russian Society of Surgeons (Moscow)

Ignatiev Igor Mikhailovich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Imaev Timur Imvyarovich, MD, PhD, Russian Scientific Society of Endovascular Diagnostics and Treatment

Kavteladze Zaza Alexandrovich, MD, PhD, Professor, Russian Scientific Society of Endovascular Diagnostics and Treatment

Kalinin Roman Evgenyevich, MD, PhD, Professor, Board Member of the Russian Society of Angiologists and Vascular Surgeons (RSOAVS), Member of the Executive Council of the Association of Phlebologists of Russia (APR), Member of the Russian Society of Surgeons (RSS), Association of Cardiovascular Surgeons of Russia (ACSR)

Karpenko Andrey Anatolyevich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Komarov Roman Nikolaevich, MD, PhD, Professor, Association of Cardiovascular Surgeons of Russia

Konradi Alexandra Olegovna, Deputy Director General for Research, Almazov National Medical Research Centre of the Russian Ministry of Health, Head of the Research Department of Arterial Hypertension, Head of the Department of Healthcare Organization, Management and Economics, Institute of Medical Education, Almazov Centre, MD, PhD, Professor, Academician of the Russian Academy of Sciences (Saint Petersburg), RSC

Lepilin Petr Mikhailovich, MD, PhD, Russian Scientific Society of Endovascular Diagnostics and Treatment

Maystrenko Dmitry Nikolaevich, MD, PhD, Russian Society of Angiologists and Vascular Surgeons

Maksimov Alexander Vladimirovich, MD, PhD, Russian Society of Angiologists and Vascular Surgeons

Malev Eduard Gennadievich, MD, PhD, Leading Research Fellow, Research Department of Non-Coronary Heart Diseases, Professor, Department of Faculty Therapy with Clinic (Saint Petersburg), RSC

Matyushkin Andrey Valeryevich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Melnikov Mikhail Viktorovich, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Mikhailov Igor Petrovich, MD, PhD, Professor, Association of Cardiovascular Surgeons of Russia, Russian Society of Surgeons, Russian Society of Angiologists and Vascular Surgeons

Polyakov Roman Sergeevich, PhD, Russian Scientific Society of Endovascular Diagnostics and Treatment

Pugina Margarita Yuryevna, Junior Research Fellow, Research Laboratory of Congenital and Acquired Heart Defects, Almazov National Medical Research Centre (Saint Petersburg), RSC

Alexander S. Pshennikov, MD, PhD, Associate Professor, Russian Society of Angiologists and Vascular Surgeons, Association of Phlebologists of Russia (APR)

Andrey B. Sazonov, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

German Yu. Sokurenko, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Vladimir V. Soroka, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Igor A. Suchkov, MD, PhD, Professor, Board Member of the Russian Society of Angiologists and Vascular Surgeons (RSAVS), President of the Association of Phlebologists of Russia (APR), Member of the Russian Society of Surgeons (RSS), Association of Cardiovascular Surgeons of Russia (ACVS), International Union of Angiology (IUA)

Irina E. Timina, MD, PhD, Russian Association of Ultrasound Diagnostics Specialists in Medicine (RASUDM)

Alexander V. Troitskiy, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Vladimir E. Uspenskiy, MD, PhD, Head of the Research Laboratory of Aortic and Aortic Valve Diseases, Associate Professor at the Department of Cardiovascular Surgery, Almazov National Medical Research Centre (Saint Petersburg), Russian Society of Cardiology (RSC), ACVS

Robert I. Khabazov, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Alexander F. Kharazov, PhD, Russian Society of Angiologists and Vascular Surgeons

Gennady G. Khubulava, Academician of the Russian Academy of Sciences, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons, Association of Cardiovascular Surgeons of Russia (ACVS)

Eduard R. Charchyan, MD, PhD, Corresponding Member of the Russian Academy of Sciences, Professor, Association of Cardiovascular Surgeons of Russia, EACTS (European Association for Cardio-Thoracic Surgery), STS (The Society of Thoracic Surgeons)

Natalia R. Chernaya, PhD, Russian Society of Angiologists and Vascular Surgeons

Alexander M. Chernyavskiy, MD, PhD, Professor, Corresponding Member of the Russian Academy of Sciences, Russian Society of Angiologists and Vascular Surgeons

Mikhail A. Chernyavskiy, MD, PhD, Head of the Research Department of Vascular and Interventional Surgery, Cardiovascular Surgeon (Saint Petersburg), RSC, ACVS

Andrey V. Chupin, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

Vladimir V. Shlomin, PhD, Board Member of the Russian Society of Angiologists and Vascular Surgeons

Aleksey A. Fokin, MD, PhD, Professor, Russian Society of Angiologists and Vascular Surgeons

George Geroulakos, (Athens, Greece), European Society for Vascular Surgery

Gustavo Oderich, (USA, Houston) Society for Vascular Surgery, European Society for Vascular Surgery and American Surgical Association.

Lazar Davidovic, (Belgrad, Serbia), European Society for Vascular Surgery

Stephan Haulon, (Paris, France) European Society for Vascular Surgery

Appendix A2. Methodology for Developing Clinical Guidelines

Target audience for these clinical guidelines:

Target audience of the developed clinical guidelines:

Cardiovascular surgeon;

Surgeon;

Cardiologist;

District general practitioner;

General practitioner (family physician).

Medical students, residents, postgraduate students.

The recommendations are based on a cumulative analysis of evidence presented in the global literature and obtained from the clinical application of modern principles and methods for the diagnosis and treatment of lower extremity varicose veins. The main provisions of the Guidelines are ranked in accordance with Order No. 103n of the Ministry of Health of the Russian Federation dated February 28, 2019, "On approval of the procedure and timelines for the development of clinical guidelines, their revision, the standard template for clinical guidelines, and requirements for their structure, composition, and scientific validity of the information included in clinical guidelines."

The National Guidelines were developed based on ESVS recommendations, taking into account national specifics, features of examination and treatment, and the availability of medical care. For this reason, the text of these clinical guidelines simultaneously uses two scales for assessing the level of evidence for recommendation statements: ESVS levels of evidence with levels of recommendation (LoR) and levels of evidence (LoE). ESVS=ESC recommendation classes have been added to assess the necessity of performing a recommendation statement.

Table App2-1. Classes of recommendations according to the European Society for Vascular Surgery (ESVS) guidelines.

Table App2-2. Levels of evidence according to the European Society for Vascular Surgery (ESVS) guidelines.

The recommendations were prepared in accordance with the Methodological Recommendations for Assessing the Scientific Validity of Information Included in Clinical Guidelines, Center for Expertise and Quality of Medical Care of the Ministry of Health of the Russian Federation, 2019.

Table App2-3. Scale for assessing levels of evidence (LoE) for diagnostic methods (diagnostic interventions)

Table App2-4. Scale for assessing levels of evidence (LoE) for methods of prevention, treatment, and medical rehabilitation, including those based on natural therapeutic factors (preventive, therapeutic, and rehabilitative interventions)

Table App2-5. Scale for assessing levels of recommendation (LoR) for methods of prevention, diagnosis, treatment, and medical rehabilitation, including those based on natural therapeutic factors (preventive, diagnostic, therapeutic, and rehabilitative interventions)

Due to the fact that the Russian Society of Cardiology (RSC) is a constituent of the European Society of Cardiology (ESC), and RSC members are also ESC members, all European guidelines are formulated with the participation of Russian experts who co-authored the guidelines. Thus, the existing ESC guidelines reflect the consensus of leading Russian and European cardiologists.

Accordingly, the national guidelines were developed based on ESC recommendations, taking into account national specifics, features of examination and treatment, and the availability of specific medical care. For this reason, during the development of the Russian clinical guidelines by the RSC, international classes of recommendation were used to assess the necessity of performing recommendation statements and the levels of evidence for these classes (Tables App2-6 and App2-7).

In cases where European guidelines lacked classes and levels of evidence, but in the opinion of RSC experts these statements were extremely necessary for implementation or, conversely, strictly not recommended for use, RSC experts—based on the rules for formulating recommendation classes according to the European Society of Cardiology guidelines—assigned the classes and levels themselves. In such instances, the ESC designation is replaced with RSC classes and levels assigned by RSC experts.

In addition, a new grading system for LoE and LoR for therapeutic, rehabilitative, preventive, and diagnostic interventions was added (Tables App2-8, App2-9, and App2-10), introduced in 2018 by the Center for Expertise and Quality of Medical Care of the Ministry of Health of the Russian Federation. Thus, the text of the clinical guidelines developed by RSC experts utilizes two scales simultaneously (Tables App2-6 – App2-10).

Table App2-6. Classes of recommendations according to the European Society of Cardiology (ESC) guidelines.

Table App2-7. Levels of evidence according to the European Society of Cardiology (ESC) guidelines.

Table App2-8. Scale for assessing levels of evidence (LoE) for diagnostic methods (diagnostic interventions)

Table App2-9. Scale for assessing levels of evidence (LoE) for methods of prevention, treatment, and medical rehabilitation, including those based on natural therapeutic factors (preventive, therapeutic, and rehabilitative interventions)

Table App2-10. Scale for assessing levels of recommendation (LoR) for methods of prevention, diagnosis, treatment, and medical rehabilitation, including those based on natural therapeutic factors (preventive, diagnostic, therapeutic, and rehabilitative interventions)

Procedure for updating clinical guidelines.

The mechanism for updating clinical guidelines provides for their systematic revision at least once every three years, as well as upon the emergence of new evidence-based medicine data on the diagnosis, treatment, prevention, and rehabilitation of specific diseases, or in the presence of justified additions/comments to previously approved clinical guidelines, but no more frequently than once every 6 months.

Appendix A3. Reference Materials

Up-to-date instructions for the medical use of drugs can be found on the official website of the Russian Ministry of Health http://grls.rosminzdrav.ru (http://grls.rosminzdrav.ru/Default.aspx).

Appendix B. Physician Action Algorithms

Figure AppB-1. Management algorithm for a patient with abdominal aortic aneurysm.

Figure AppB-2. Management algorithm for patients with abdominal compartment syndrome after open or endovascular reconstructive surgery for a ruptured abdominal aortic aneurysm. IAP – intra-abdominal pressure.

Figure AppB-3. Follow-up algorithm after endovascular aneurysm repair with patient stratification based on initial imaging results. All patients should be offered lifelong follow-up, including abdominal aortic CTA at least once every 5 years. If necessary, more frequent imaging can be performed using abdominal aortic CTA or aortic duplex ultrasound depending on the imaging objective (abdominal aortic CTA is required to assess the length of the sealing zone and the integrity of the endovascular abdominal aortic stent graft; assessing the presence of endoleaks and aneurysmal sac size can be performed using aortic duplex ultrasound).

Table AppB-1. Proposed diagnostic criteria for mycotic aortic aneurysm [23].

Table PB-2. Proposed morphological variables for assessing outcomes of endovascular aortic repair with fenestrated and branched stent-grafts

Table PB-3. Overview of conservative treatment methods for intra-abdominal hypertension/abdominal compartment syndrome.

Table PB-4. Imaging modalities applicable for detecting complications of endovascular aneurysm repair and used in follow-up (adapted from Dellagrammaticas et al. [495]).

Appendix C. Patient Information

The next part of the document contains the same information, but presented in a format for non-specialists. Detailed information on the process used to develop this information and the level of evidence for each piece of information is provided at the end of this section. Where very high-level evidence is available regarding the management of patients with AAA, it has been included in the information presented here.

What is an abdominal aortic aneurysm?

An abdominal aortic aneurysm is a widening or ballooning of the body's main artery as blood passes through the abdomen to the legs. These aneurysms very rarely occur under the age of 60. They are more common in people who have ever smoked (current or former smokers) than in those who have never smoked. They are also more common in men than in women. In rare cases, an abdominal aortic aneurysm may be genetically determined.

Most aneurysms cause no symptoms, and patients with an aneurysm usually do not know they have one until it is detected by a doctor during medical examinations or in the event of its rupture.

How is an abdominal aortic aneurysm diagnosed?

Sometimes a doctor discovers an aneurysm during a physical examination. However, this is an unreliable method for diagnosing an aneurysm.

If an abdominal aortic aneurysm is suspected, the best way to confirm the diagnosis is to use a special type of ultrasound (US) imaging – duplex ultrasound of the aorta. This is a good non-invasive method for examining the aorta in the back of the abdomen (where aneurysms most commonly form). Ultrasound does not involve any radiation and is quick and simple to perform. In many cases, the presence of an aneurysm is not suspected until it is diagnosed, and most people diagnosed with an aneurysm usually undergo scanning for another reason or as part of a screening program (see below).

More detailed information about an aneurysm can be obtained using computed tomography (CT). This involves injecting a contrast agent into your vein, which can be seen on the scan. This contrast agent clearly shows the details of the arteries and the aneurysm. This is a good method for viewing blood vessels and parts of the aneurysm that are not visible on ultrasound (for example, parts of the aorta in the chest). Computed tomography is most commonly used when considering surgical repair of an aneurysm, or if your doctor wants to make sure the aneurysm has not ruptured. A doctor may suspect an aneurysm rupture if a patient with a confirmed aneurysm suddenly develops severe abdominal or back pain, or experiences loss of consciousness.

How is screening for abdominal aortic aneurysm performed?

Offering men aged 65 (or older) a screening abdominal ultrasound (comprehensive) reduces the risk of death from an aneurysm by detecting it before rupture. Offering screening actually helps increase the number of patients who are indicated for surgical aneurysm repair, and these operations are much safer than leaving the aneurysm untouched. Screening has been proven to be cost-effective in men, but there is currently no information on whether women will benefit from screening.

We recommend offering all men aged 65 a single abdominal ultrasound (comprehensive) for the presence of an abdominal aortic aneurysm.

What happens if I am diagnosed with an abdominal aortic aneurysm?

If an abdominal aortic aneurysm is found, you will be told whether it is small (3 cm to 5 cm) or large (5 cm or more). The size of the aneurysm is usually measured by abdominal ultrasound (comprehensive) in the anteroposterior direction. When measured by abdominal CTA, the size is usually slightly larger than when measured by abdominal ultrasound (comprehensive). However, the measurement by abdominal ultrasound (comprehensive) is the most important.

As long as the aneurysm remains small, it is unlikely to cause you any problems, but you will need to monitor the size of the aneurysm regularly, even if a three-year surveillance interval is scheduled for small aneurysms.

If I am diagnosed with an abdominal aortic aneurysm, what is the risk of rupture?

If your aneurysm is small, the risk of rupture is extremely low. The risk of aneurysm rupture increases as its size increases. For a 3.0 cm diameter aneurysm, the one-year risk of rupture is approximately 1 in 2,000 (0.005%) for men and 1 in 500 (0.02%) for women. For a 5.0 cm diameter aneurysm, the risk is approximately 1 in 150 (0.66%) for men and 1 in 30 (3.3%) for women. The risk of rupture is known to increase for aneurysms greater than 5 cm in diameter, but since most patients with large aneurysms are offered surgery, the risk of rupture in patients with large aneurysms is unknown. For aneurysms greater than 5 cm in diameter, the risk is approximately 1 in 10 per year, but it is higher for very large aneurysms.

What can I do to stop the aneurysm from growing?

At present, there is no strong evidence that any specific intervention (medication, diet, or exercise) can stop an aneurysm from growing. However, if you are a smoker, this contributes to faster aneurysm growth. Quitting smoking reduces the likelihood of rapid aneurysm growth.

Will having an aneurysm affect other parts of my body or my overall health?

The presence of an AAA is often a warning sign of disease in other blood vessels, including those supplying the heart. This is not a direct consequence of having an aneurysm. Rather, the same causes that lead to aneurysm formation, such as smoking, also cause pathological changes in other blood vessels. Therefore, in addition to improving your physical fitness, your doctor may recommend that you take one or more medications to reduce the likelihood of future heart problems or stroke. We recommend prescribing cholesterol-lowering medications (statins) to all individuals diagnosed with an AAA to reduce the risk of other cardiovascular diseases.

What happens if my small aneurysm starts to grow?

If the aneurysm grows and becomes a large aneurysm, your doctor is likely to recommend surgical aneurysm repair. This does not happen to many patients throughout their lifetime. We recommend referring men to a vascular surgeon if an AAA grows to 5 cm or greater to consider surgical repair.

In women, a diameter of 4.5 cm is typically used as the threshold for surgical referral. Some specialists recommend referring women for surgery when the aneurysm diameter reaches 5.0 cm. There is currently no evidence for or against a different recommendation for women, and the decision should be made after consultation with your doctor or vascular surgeon. Women are known to have a higher rate of aneurysm rupture than men; however, surgical aneurysm repair carries higher risks in women than in men.

What happens if I am referred to a vascular surgeon to discuss surgery?

After you are examined by a cardiovascular surgeon to discuss further treatment tactics for an abdominal aortic aneurysm, it is necessary to consider the main question regarding whether you will benefit from surgical repair. Not every patient with an abdominal aortic aneurysm can benefit from reconstructive surgery. This is because there are risks associated with open or endovascular repair of an abdominal aortic aneurysm. If these risks outweigh the risk of aneurysm rupture, surgery is not recommended.

Typically, two types of surgery are performed: open repair and endovascular (minimally invasive) repair. We recommend that for patients who are candidates for both open and endovascular repair, the choice of surgical approach should be based on the patient's personal preferences. This decision should be made after consultation with a cardiovascular surgeon. For patients who are at a somewhat higher risk than usual due to other health problems, we recommend endovascular repair.

For men, the risk of death from complications during or immediately after elective surgery is approximately 1 in 25 (4%) for open repair and 1 in 140 (0.7%) for endovascular repair. The risks associated with surgery are higher in women: approximately 1 in 15 (6.9%) for open repair and 1 in 55 (1.8%) for endovascular repair.

How is abdominal aortic aneurysm repair performed?

Open abdominal aortic aneurysm repair is performed through a large incision in the abdominal wall. The aorta in the retroperitoneum is isolated, and blood flow through the aorta is temporarily clamped. Then, a vascular graft is sewn into place in place of the aneurysmal segment, and aortic blood flow is restored.

Endovascular repair is performed through small incisions in the groin. Under fluoroscopic guidance, a stent-graft (a vascular prosthesis with a spring framework) is inserted into the aorta via the femoral arteries.

Once the graft is positioned in the correct place, it is deployed. Often, the implantation of three or four graft components is required, but upon completion of this procedure, the endograft relieves tension on the aneurysm wall. Not all patients are candidates for endovascular aortic repair. One of the aspects that surgeons evaluate when examining patients with abdominal aortic aneurysms is their suitability for endovascular repair. Approximately 70–80% of aneurysm patients are candidates for endovascular repair.

What are the main advantages and disadvantages of open versus endovascular abdominal aortic aneurysm repair?

The main advantage of endovascular repair compared with open repair is the shorter hospital stay and the lower procedure-related risk. The main disadvantage of endovascular repair is that you will need postoperative follow-up with your surgeon to ensure that the endograft does not migrate or develop endoleaks. Some patients will require additional surgery in the future to replace or revise the endograft, which creates additional risks over time. When comparing groups of patients who underwent open versus endovascular aneurysm repair over long periods of time (years), the risks are comparable. As part of postoperative monitoring, CT scans involving X-ray radiation are sometimes required, which carries a very small theoretical risk of malignancies and kidney disease. In the past, many surgeons believed that follow-up was unnecessary after patients recovered from open surgery. This was considered one of the advantages of open surgery, and therefore many patients preferred open repair. However, our working group for the development of Russian Clinical Guidelines, represented by leading domestic and foreign experts in the treatment of abdominal aortic and iliac aneurysms, recommends offering patients regular abdominal imaging after abdominal aortic aneurysm repair—whether endovascular or open—to assess the effectiveness of the reconstruction and to detect any new additional aneurysms in adjacent arteries.

What happens if I have medical contraindications to aneurysm repair surgery?

Some patients have elevated risks associated with aneurysm repair surgery. For example, individuals with pulmonary or renal disease are more likely to experience postoperative complications. If the risk associated with surgery outweighs the risk of rupture, surgeons generally recommend postponing the surgery until the aneurysm enlarges or avoiding it altogether.

There are very limited data on the optimal management strategy when medical contraindications to surgery cannot be resolved. In medically unfit patients, aneurysm repair will most likely prevent rupture, but there is no evidence that such surgery prolongs life. If you are a smoker, smoking cessation will reduce the risk of aneurysm growth and rupture.

If a patient insists on undergoing aneurysm repair surgery, the average risk of operative mortality is approximately 7% (1 in 14 compared to 1 in 50 or 1 in 100 in patients without medical contraindications). It should be noted that this average risk applies across all patients with medical comorbidities. Many patients are at a higher risk, and the decision to operate must be made based on the recommendations of the surgeon and the anesthesiologist-intensivist as part of the surgical risk assessment.

What happens if the aneurysm ruptures?

An aneurysm rupture is a medical emergency. If you have an aneurysm and experience sudden, severe back or abdominal pain or loss of consciousness, you should seek medical attention immediately and be sure to inform healthcare providers that you have an aneurysm. Unfortunately, many do not survive an aneurysm rupture. Those who reach the hospital may undergo emergency surgery. Such surgery carries a much higher risk than elective surgery; approximately one in every three patients does not survive a ruptured AAA repair. Many surviving patients require many months to recover or become physically disabled. Because of these risks, some patients decline reconstructive surgery for a ruptured aneurysm, even though nearly all patients with a ruptured aneurysm die within a few days.

For a ruptured aneurysm, the same surgical approaches can be used as in elective treatment. Based on the latest evidence, we recommend endovascular repair as the method of choice, whenever feasible, in patients with a ruptured aneurysm who are anatomically suitable for this procedure.

Rare causes of abdominal aortic aneurysm

In most cases, aneurysm formation is caused by a combination of a person's genetic background, which predisposes certain groups to AAA development, and external factors such as smoking. These combined factors disrupt the structure of the aortic wall and lead to aneurysm formation. In rare cases, aneurysm development may be caused by other factors. It is difficult to develop treatment guidelines for these rare aneurysms because we generally know less about conditions that are uncommon.

Aneurysms occur in association with certain hereditary disorders. In such cases, treatment is typically managed by clinical geneticists in collaboration with surgeons if the patient is a candidate for aortic reconstruction. In most of these patients, open repair is preferable to endovascular repair.

Most rare aneurysms occurring at an older age develop on the background of infection, inflammation, or other aortic diseases. The management of these aneurysms may differ from that of common aneurysms, and therefore the recommendations above may not apply to you. If your doctor believes your aneurysm is caused by one of these conditions, they will inform you and explain the best treatment for you.

Appendix G. Assessment Scales, Questionnaires, and Other Evaluation Tools

Appendix G1. CHA2DS2-VASc Score for Stroke and Systemic Thromboembolism Risk Assessment in Patients with Atrial Fibrillation

Russian title: CHA2DS2-VASc Score for Stroke and Systemic Thromboembolism Risk Assessment in Patients with Atrial Fibrillation

Original title (if applicable): CHA2DS2-VASc Score for Stroke Risk Assessment in Atrial Fibrillation

Source: [496]

Type: rating scale

Purpose: Assessment of stroke and systemic thromboembolism risk factors in patients with atrial fibrillation

Content (template):

Table G1. Scale for assessing the risk of stroke and systemic thromboembolism in patients with atrial fibrillation (CHA2DS2-VASc)

Note: BP – blood pressure, ICH – intracranial hemorrhage, HCM – hypertrophic cardiomyopathy, PAD – peripheral artery disease, OAC – oral anticoagulants, LV – left ventricle, RCT – randomized controlled trial, HF – heart failure, HFrEF – heart failure with reduced ejection fraction, HFpEF – heart failure with preserved ejection fraction, TIA – transient ischemic attack, LVEF – left ventricular ejection fraction, AF – atrial fibrillation.

Key (interpretation): Long-term use of oral anticoagulants for the prevention of thromboembolic events is recommended for male patients with a CHA2DS2-VASc score ≥ 2 and female patients with a CHA2DS2-VASc score ≥ 3.

The administration of oral anticoagulants for the prevention of thromboembolic events is recommended for men with CHA2DS2-VASc = 1 and women with CHA2DS2-VASc = 2, taking into account individual patient characteristics and preferences.

Appendix G2. Society for Vascular Surgery (SVS) Comorbidity Scoring System

Russian title: Society for Vascular Surgery (SVS) Comorbidity Scoring System

Source: [8, 72, 198]

Type: rating scale

Purpose: Assessment of stroke and systemic thromboembolism risk factors in patients with atrial fibrillation

Content (template):

Table G2. Society for Vascular Surgery (SVS) Comorbidity Scoring System

Note: EVAR – endovascular abdominal aortic aneurysm repair; FEV1 – forced expiratory volume in 1 second; Pco2 – partial pressure of carbon dioxide.

Key (interpretation): Calculation method: sum of (score × weight) for each organ system = total score.

0–4 points – low predicted mortality risk

5–7 points – intermediate predicted mortality risk

8–10 points – high predicted mortality risk

≥ 11 points – extremely high predicted mortality risk