Holter ECG

Aspect à l'ECG

A Holter recording is not a separate ECG pattern, but a long strip analyzed using the same principles as a standard ECG, but with an emphasis on time dynamics.

Key report parameters:

Leads in most recorders are modified chest leads (analogs of V1, V5 or similar bipolar leads); modern systems can record from 2 to 12 channels. Localization of ischemia cannot be reliably assessed from 2–3 channels; standard monitoring does not replace a 12-lead ECG, especially when acute coronary syndrome is suspected.

Indications

Main groups of indications:

• complaints of palpitations, skipped beats, presyncope, or syncopal episodes of unclear etiology on a standard ECG;
• assessment of the efficacy of antiarrhythmic therapy or heart rate control in atrial fibrillation;
• suspected sick sinus syndrome, pauses, high-degree AV blocks;
• in specific clinical situations — evaluation of suspected myocardial ischemia (ST monitoring does not replace stress imaging or standard 12-lead ECG); heart rate variability (HRV) analysis is used primarily as an additional research or prognostic parameter, rather than a standalone routine indication;
• after catheter ablation — as indicated, to assess arrhythmia recurrence; after pacemaker or implantable cardioverter-defibrillator placement, the primary monitoring method is in-person or remote device interrogation, with standard Holter used additionally for persistent symptoms or suspected unrecognized arrhythmias;
• screening in athletes with suspicious findings on resting ECG or a family history of sudden death;
• monitoring during pregnancy in case of complaints of extrasystoles or tachycardia paroxysms;
• assessment of arrhythmias in children, including suspected long QT syndrome, WPW, frequent extrasystoles.

Specific features in children, athletes, and pregnant women

In children, heart rate and its daily fluctuations are wider than in adults; sinus arrhythmia and wandering pacemaker during sleep are normal variants. Heart rate thresholds are interpreted using age-specific norms rather than adult tables.

In athletes with high vagal tone, Holter may reveal nocturnal sinus bradycardia, sinoatrial pauses, wandering pacemaker, first-degree AV block, or Mobitz I with a narrow QRS. Interpretation depends on the duration and mechanism of the pause, recurrence, time of day, presence of symptoms, and response to awakening or exertion, rather than just the presence of a pause on a single recording. In trained individuals, nocturnal pauses, including those around 3 seconds, without symptoms and with a normal chronotropic response, are often considered benign, but longer pauses, repeated episodes, daytime pauses, or lack of adequate heart rate increase require separate evaluation. Any pause around or exceeding 3 seconds, especially during the day or with symptoms, as well as Mobitz II, high-grade, or complete AV block, requires urgent evaluation regardless of athletic status.

During pregnancy, Holter is ordered for complaints of palpitations or detected extrasystoles: physiological tachycardia and increased frequency of extrasystoles in the second half of pregnancy are common findings without structural heart disease, but persistent tachyarrhythmia requires further workup.

Diagnostics différentiels

The main goal is not to mistake a recording artifact for real arrhythmia:

• electrode detachment or motion artifact — can mimic a pause or wide complex; distinguish by checking all available channels simultaneously, baseline quality, sudden signal loss or distortion, and preservation of physiological complexes before and after the event — the mere absence of a P wave on a single channel is insufficient, as P may be obscured by the chosen lead;
• muscle tremor — resembles fine atrial fibrillation, but the underlying rhythm can usually be traced beneath the artifact;
• isolated short sinus pause during sleep in a healthy person (especially an athlete) — not the same as pathological sinoatrial block with symptoms;
• physiological nocturnal bradycardia — not sick sinus syndrome if there are no symptomatic pauses and an adequate daytime heart rate increase is preserved.

Valeur clinique et prise en charge

Holter is a diagnostic method for transient rhythm and conduction disorders, not a replacement for a resting ECG: it is not intended for the emergency diagnosis of acute coronary syndrome — this requires an immediate 12-lead ECG and troponin assessment.

When analyzing the report, the physician:

• correlates findings with the patient's symptom diary — asymptomatic extrasystole and symptomatic pause require different management;
• assesses ectopy burden as a percentage: a proportion of ventricular extrasystoles around ≥10% of total daily complexes is an indication to assess heart structure and function (Echocardiography) and consider PVC-induced cardiomyopathy, but the percentage alone does not equate to cardiomyopathy; the scope of further workup, including cardiac MRI, is determined by the clinical context — duration of exposure, morphology and width of ventricular QRS, left ventricular function, family history, and structural changes;
• in sustained ventricular tachycardia, syncope associated with arrhythmia, high-grade or complete AV block, provides immediate clinical evaluation and hospitalization as indicated — these are potentially life-threatening findings, not a reason for routine referral; further echocardiography, MRI, electrophysiological study, and device implantation decisions are performed urgently as indicated, and stress testing is performed only after safety assessment, as it may be contraindicated in certain ventricular tachycardias or high-grade blocks;
• if a short recording is inconclusive in cases of rare symptoms, considers longer ambulatory monitoring (external recorder up to 30 days) or an implantable loop recorder.

Erreurs fréquentes lors de l'interprétation

• interpreting any nocturnal bradycardia and pause in an athlete as an unconditional norm without assessing duration, mechanism, and symptoms;
• mistaking a motion artifact or detached electrode for arrhythmia based on a single channel;
• drawing conclusions from a single channel without considering QRS morphology in the context of the rest of the recording.
• surestimer les modifications du segment ST sur un enregistrement à 2-3 canaux comme une preuve d'ischémie sans corrélation clinique ;
• reporter une évaluation urgente en cas de TV soutenue ou de bloc AV de haut degré, en les interprétant comme une trouvaille anodine pour un bilan de routine ;
• appliquer les normes adultes de fréquence cardiaque et de pauses aux enfants sans correction liée à l'âge.

Foire aux questions

Termes associés

À lire également dans la rubrique « Enfants, sportifs, femmes enceintes »

Toute la section

Sources

• Orlov V.N. Guide d'électrocardiographie
• Hampton J.R. The ECG in Practice
• Surawicz B., Knilans T.K. Chou's Electrocardiography in Clinical Practice

Matériel pédagogique destiné aux étudiants en médecine et aux médecins. Ne remplace pas les recommandations cliniques ni l'examen médical ; l'ECG s'interprète toujours conjointement avec la clinique.