Definition and causes of coronary artery disease
Coronary artery disease (CAD) is one of the leading causes of mortality globally. The underlying mechanism is the narrowing of a coronary artery, which prevents adequate blood supply to the myocardium. The primary cause of this narrowing is atherosclerosis.
Traditional risk factors include:
- diabetes mellitus
- smoking;
- overweight
- sedentary lifestyle
- arterial hypertension
- dyslipidemia
Social factors are distinguished separately: chronic stress, busy work schedules, lack of rest, and urban living conditions. Notably, individuals with higher income levels also have an increased risk of developing CAD, which is associated with a combination of these factors.
Clinical manifestations: angina pectoris
The primary symptom of CAD is angina pectoris, a symptom complex that includes retrosternal burning and heaviness, and pain that may radiate to the neck, lower jaw, left arm, and epigastric region. A patient's characteristic gesture of placing a clenched fist against the chest to describe the sensation of heaviness is termed Levine's sign.
When an atherosclerotic plaque occludes more than 70% of the coronary artery lumen, it is referred to as critical stenosis; clinical manifestations typically appear precisely with this degree of lesion. Complete occlusion of the arterial lumen is termed occlusion, while a 98–99% narrowing is called subocclusion.
Diagnosis of CAD
Diagnostic workup begins with taking a medical history and evaluating symptoms characteristic of angina, although the disease can also be asymptomatic. A range of methods is used to confirm the diagnosis:
- Standard ECG — in the presence of angina at the time of recording, ST-segment changes are usually detected: ST-segment depression indicates ischemia, while elevation indicates acute myocardial infarction.
- Stress tests (stress ECG, treadmill test) — electrodes and a blood pressure cuff are placed on the patient, after which they walk on a treadmill with gradually increasing workload. In cases of critical arterial lesions, ST-segment changes or left bundle branch block may be detected.
- Ventricular wall hypokinesia — reduced wall motion indicating acute ischemia or prior myocardial infarction; impaired contractility compromises systemic blood flow, primarily to the brain.
- Coronary angiography — a minimally invasive procedure and the gold standard for diagnosing CAD. It is performed via puncture of the radial (preferred) or femoral artery, advancing a catheter to the ostia of the coronary arteries, and injecting a contrast agent under X-ray guidance. It allows visualization of stenosis, occlusion, thrombus, and the anatomical features of the coronary vascular bed.
Coronary angiography is always performed following a preliminary ECG evaluation.
Pharmacotherapy
In the absence of critical stenosis on coronary angiography, conservative therapy is applied. The standard regimen includes:
- antiplatelet agents (aspirin)
- nitrates
- heparin and direct anticoagulants
- glycoprotein IIb/IIIa receptor inhibitors
- beta-blockers
- ACE inhibitors
Aspirin is prescribed to virtually all patients. According to clinical guidelines, an unstable patient with angiographically confirmed disease is administered a loading dose of aspirin of 160–320 mg orally (chewing the tablet is recommended for a rapid effect), and the maintenance dose is 75–100 mg daily long-term. For clopidogrel, the loading dose is 600 mg; if fibrinolytic therapy was previously administered for myocardial infarction when coronary angiography was unavailable, a 300 mg dose is administered.
Surgical treatment
If significant stenosis is detected on coronary angiography, revascularization options are considered:
- Balloon angioplasty — dilation of the coronary artery lumen by inflating a balloon.
- Stenting (percutaneous coronary intervention, PCI) — placement of a drug-eluting metal mesh scaffold that keeps the vessel lumen open and restores normal blood flow.
- Coronary artery bypass grafting (CABG) — the gold standard of surgical treatment for CAD. The procedure involves creating a bypass blood flow route around the diseased arterial segment using conduits (grafts). Most commonly, the internal thoracic artery originating from the left subclavian artery is used; the radial artery from the left arm is also used according to guidelines, while the greater saphenous vein of the leg is considered a less preferred but acceptable option.
The choice of revascularization method depends on lesion anatomy, left ventricular function, patient preferences and lifestyle, and comorbid chronic conditions. The patient must be informed of the risks associated with each treatment method.
Clinical forms of CAD and management in acute infarction
Several clinical forms of CAD are distinguished: stable angina, unstable angina, as well as ST-segment elevation myocardial infarction and non-ST-segment elevation myocardial infarction.
- Stable angina — pain is predictable, occurs upon physical exertion, and subsides at rest; stress ECG and coronary angiography reveal arterial stenosis. Treatment includes nitrates, beta-blockers, calcium channel blockers, risk factor modification, and CABG or stenting when indicated.
- Unstable angina — pain is more pronounced, lasts longer than 20 minutes, and may occur at rest. Coronary angiography reveals a thrombus or ruptured atherosclerotic plaque, ECG shows ST-segment depression, and myocardial injury markers (troponin, CK-MB) are typically not elevated. Surgical treatment involves PCI or CABG.
- Acute myocardial infarction — pain is maximally severe, and the attack may occur suddenly. ECG shows ST-segment elevation or pronounced depression, and laboratory tests show elevated troponin and CK-MB fractions. The primary treatment method is emergency stenting to restore blood flow; if mechanical complications develop (acute mitral regurgitation due to papillary muscle rupture, ventricular septal rupture, or cardiac wall rupture), urgent open surgical intervention is required.
In cases of ST-segment elevation and symptoms lasting less than 12 hours, the primary strategy is emergency stenting, ideally within 120 minutes of first medical contact; if PCI is not feasible, emergency coronary artery bypass grafting is considered. Stenting is considered the method of choice for emergency care, whereas bypass surgery remains the gold standard for elective surgical treatment of CAD.
Key points
- CAD is the narrowing of a coronary artery, most commonly due to atherosclerosis, leading to inadequate myocardial blood supply.
- Critical stenosis is a narrowing of the arterial lumen by more than 70%, accompanied by clinical manifestations of angina.
- The primary symptom is angina pectoris: retrosternal burning and heaviness with characteristic radiation of pain.
- Diagnosis includes ECG, stress tests, and coronary angiography as the gold standard for visualizing the coronary vasculature.
- ST-segment depression indicates ischemia, while ST-segment elevation indicates acute myocardial infarction.
- Drug therapy includes antiplatelet agents, nitrates, anticoagulants, beta-blockers, and ACE inhibitors.
- Surgical treatment includes balloon angioplasty, stenting, and coronary artery bypass grafting, with the choice depending on the patient's anatomy and condition.
- In acute myocardial infarction, emergency revascularization is prioritized, predominantly via stenting.