1. Introduction

Arrhythmogenic right ventricular cardiomyopathy (ARVC), historically termed arrhythmogenic right ventricular dysplasia (ARVD), is an inherited myocardial disease characterized by progressive loss of cardiomyocytes and fibrous or fibro-fatty replacement, classically involving the right ventricle. Left-ventricular involvement may coexist, and some families show a biventricular or left-dominant phenotype. The broader term arrhythmogenic cardiomyopathy (ACM) encompasses this phenotypic spectrum.

The disease creates an electrically and structurally heterogeneous myocardium that supports ventricular ectopy, re-entrant ventricular tachycardia, and potentially sudden cardiac death. Exercise may increase arrhythmic risk and can accelerate phenotypic expression in susceptible individuals. Presentation ranges from incidental ECG abnormalities to exertional palpitations, syncope, sustained VT, aborted cardiac arrest, or later ventricular dysfunction.

2. Electrophysiology and Pathophysiology

Desmosomal and other disease-associated variants can impair mechanical coupling between cardiomyocytes. Repeated mechanical stress, particularly during intense endurance or competitive exercise, contributes to myocyte injury and replacement fibrosis. Fibrous and fatty tissue interspersed with surviving myocardium produces regions of slow and non-uniform conduction.

3. Characteristic ECG Features

3.1 T-wave inversion in right precordial leads

T-wave inversion in V1–V3, in the absence of complete right bundle branch block (RBBB), is a major repolarization criterion in the 2010 Revised Task Force Criteria in individuals older than 14 years. T-wave inversion limited to V1–V2 is less specific and may be a normal variant in some individuals. Interpretation must account for age, ethnicity, lead placement, and the presence of RBBB.

3.2 Epsilon wave

An epsilon wave is a low-amplitude signal between the end of the QRS complex and the onset of the T wave, typically in V1–V3. It has traditionally been regarded as a depolarization marker of delayed right-ventricular activation. However, epsilon waves are difficult to define reproducibly, are vulnerable to filtering and recording conditions, and show substantial interobserver variability. The 2023 ESC guideline advises caution because of frequent overdiagnosis and limited incremental diagnostic value.

3.3 Terminal activation delay and S-wave upstroke

A prolonged terminal activation duration (TAD) is measured from the nadir of the S wave to the end of the QRS complex, including any R′, in V1, V2, or V3. A value of ≥55 ms in the absence of complete RBBB is a minor depolarization criterion in the 2010 Task Force framework. A delayed S-wave upstroke and localized right-precordial QRS prolongation may provide visual clues, but should not be substituted for the formal measurement.

3.4 Ventricular ectopy and ventricular tachycardia

Ventricular premature beats (VPBs) and VT with LBBB morphology suggest a right-ventricular origin. Under the 2010 criteria, more than 500 ventricular extrasystoles per 24 hours is a minor arrhythmia criterion. VT with LBBB morphology and a superior axis is a major criterion; an RV outflow tract (RVOT) pattern with inferior axis is a minor criterion. A single LBBB/inferior-axis VT morphology is not specific for ARVC and may occur in idiopathic RVOT VT.

3.5 Additional ECG observations

• Localized QRS prolongation or terminal conduction delay in V1–V3.
• Low QRS voltage in limb leads may occur, particularly with more extensive or left-ventricular disease, but is not specific.
• Ventricular ectopy may increase with exercise or adrenergic stimulation.
• A normal resting ECG does not exclude early or concealed disease.

4. Systematic ECG Interpretation

1. Confirm technical quality. Check calibration, paper speed, limb and precordial lead placement, artefact, and whether a complete RBBB is present. Standard calibration is usually 25 mm/s and 10 mm/mV.
2. Assess rhythm and ectopy. Identify sinus rhythm, premature ventricular complexes, couplets, nonsustained VT, or sustained VT. Document the frequency and morphology of ventricular ectopy.
3. Inspect right-precordial repolarization. Examine T waves in V1–V3. Determine whether inversion extends beyond V1 and whether complete RBBB or another explanation is present.
4. Inspect terminal QRS activation. Look for a discrete epsilon-like signal and measure TAD from the S-wave nadir to the end of QRS in V1–V3. Avoid calling baseline noise or fragmented QRS an epsilon wave.
5. Characterize any VT. LBBB morphology suggests a right-ventricular origin. Determine axis: superior-axis VT is more concerning for ARVC than a typical inferior-axis RVOT pattern.
6. Integrate, do not overcall. Correlate ECG findings with symptoms, family history, ambulatory monitoring, echocardiography, CMR, and genetic assessment. The ECG alone is insufficient to establish ARVC.

5. Diagnostic Criteria: What the ECG Can and Cannot Establish

The 2010 Revised Task Force Criteria use a combination of six diagnostic domains. Findings are classified as major or minor; diagnosis depends on the combination across categories rather than any single ECG feature.

Diagnostic classification under the 2010 framework: definite ARVC requires two major criteria, or one major plus two minor criteria, or four minor criteria from different categories. Borderline and possible categories are also defined by lesser combinations. Criteria must be applied using the full published framework and appropriate age-specific considerations.

Epsilon-wave caution: Although an epsilon wave is a major depolarization criterion in the 2010 framework, the 2023 ESC guideline emphasizes frequent overcalling and poor interobserver agreement. It should not be used as a stand-alone diagnostic label.

6. Fontaine Leads

Fontaine bipolar precordial leads (F-ECG) were developed to improve visualization of right-ventricular electrical activity and may increase the visibility of epsilon waves in selected cases. They are an adjunct to, not a replacement for, the standard 12-lead ECG.

• Right arm (RA): over the manubrium.
• Left arm (LA): over the xiphoid process.
• Left leg (LL): in the standard V4 position (fifth intercostal space, midclavicular line).

The three bipolar chest leads are designated FI, FII, and FIII. The supplied source notes that the vertical FI lead may accentuate atrial potentials and can assist in examining epsilon waves or AV dissociation during VT.

7. Differential Diagnosis

8. Clinical Significance and Red Flags

• Palpitations, exertional presyncope or syncope, and documented ventricular arrhythmias may be the first manifestations.
• Sudden cardiac death can occur before overt ventricular dysfunction is recognized.
• Progressive RV dysfunction and later biventricular heart failure may develop.
• Risk assessment is individualized and incorporates prior cardiac arrest or sustained VT, arrhythmic syncope, ventricular function, arrhythmia burden, genotype, and other clinical markers.

9. Clinical Evaluation and Management Principles

Diagnostic evaluation

• History and family assessment: characterize exertional symptoms, syncope, prior arrhythmia, exercise exposure, and a three-generation family history where possible.
• 12-lead ECG and ambulatory monitoring: document repolarization/depolarization abnormalities and quantify ventricular ectopy or NSVT.
• Cardiac imaging: echocardiography assesses RV size and function; cardiac magnetic resonance (CMR) is central to detailed RV assessment and can identify LV involvement and myocardial tissue abnormalities.
• Genetic counselling/testing: consider testing for disease-associated variants and cascade clinical screening of first-degree relatives in an appropriately counselled family.
• Exclude phenocopies: consider myocarditis, sarcoidosis, RV infarction, pulmonary hypertension, congenital shunts, and idiopathic RVOT VT.

Management principles

• Exercise: patients with a clinical diagnosis should avoid competitive and high-intensity endurance exercise; individualized advice should be provided by an experienced team. Exercise restriction is also relevant to genotype-positive individuals.
• Arrhythmia management: beta-blockers are commonly used to reduce adrenergic drive and arrhythmia burden. Other antiarrhythmic therapy is selected according to symptoms, arrhythmia type, ventricular function, and specialist assessment.
• Catheter ablation: may reduce recurrent VT or ICD therapies, but does not eliminate the progressive myocardial substrate or replace an ICD when one is indicated.
• ICD: consider for secondary prevention after cardiac arrest or sustained haemodynamically significant VT, and for selected patients at high predicted risk after shared decision-making. An epsilon wave or isolated T-wave inversion is not, by itself, an ICD indication.
• Heart failure: treat ventricular dysfunction using contemporary guideline-directed heart-failure therapy and specialist follow-up.
• Family screening: provide genetic counselling and clinical evaluation for at-risk relatives. Follow-up intervals depend on age, genotype, and phenotype.

10. Common Interpretation Pitfalls

• Diagnosing ARVC solely because T waves are inverted in V1 or V1–V2, without considering age, normal variants, RBBB, and clinical context.
• Calling baseline noise, QRS fragmentation, or a terminal R′ an epsilon wave without a reproducible signal clearly separated from the QRS.
• Measuring terminal activation duration from the wrong reference point; it is measured from the nadir of the S wave to the end of QRS.
• Equating any LBBB-morphology VT with ARVC. Idiopathic RVOT VT often has an inferior axis and may occur in a structurally normal heart.
• Assuming a normal resting ECG excludes early disease.
• Using the old term “fatty infiltration” as if fat alone were diagnostic. Diagnosis depends on the integrated phenotype, not a nonspecific visual impression of fat.
• Using historical treatment statements from the source PDF as current universal recommendations.

11. ECG Pearls and Quick Reference

12. References