ECG Signs of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)
The ECG is abnormal in over 60% of ARVC patients and demonstrates characteristic depolarization and repolarization abnormalities that predominantly affect the right precordial leads. 1
Primary Depolarization Abnormalities
T-Wave Inversion (Most Common Finding)
- T-wave inversion in right precordial leads V1-V3 is the most frequent ECG abnormality in ARVC, occurring in approximately 29% of patients at baseline 1, 2
- When left ventricular involvement is present, T-wave inversion extends to lateral leads (V4-V6, I, aVL) 1
- T-wave inversion in inferior leads (II, III, aVF) reflects right ventricular infero-posterior wall involvement 1
- This finding is considered an abnormal ECG pattern requiring further cardiac evaluation to exclude ARVC 1
QRS Complex Abnormalities
- Prolonged QRS duration >110 ms in right precordial leads (V1-V3), often with right bundle branch block pattern 1
- Localized QRS prolongation specifically in V1-V3 (>110 ms) is a diagnostic marker 1, 3
- Delayed S-wave upstroke >55 ms in leads V1-V2 is a specific finding 1
- Poor R-wave progression in right precordial leads is commonly observed 3
- Low QRS voltages in precordial leads occur significantly more frequently than in healthy subjects 3
Epsilon Wave
- A terminal notch in the QRS complex appearing as a low-amplitude signal between the end of QRS and onset of T-wave in leads V1-V3 1
- This is characteristic but relatively infrequent, seen in only 16% of patients at baseline 1, 2
- Must be distinguished from benign QRS notching patterns and technical artifacts 4
Repolarization Abnormalities
- ST-segment elevation may be present in V1-V3 3
- Repolarization changes reflect myocardial areas of disease involvement 1
Left Ventricular Variant Patterns
When ARVC predominantly affects the left ventricle:
- Low voltages of R/S wave in limb leads 1
- Diffuse T-wave abnormalities extending beyond right precordial leads 1
- Inferior and/or lateral T-wave inversion with ventricular arrhythmias suggesting left ventricular origin 1
Signal-Averaged ECG Findings
- Late potentials are observed in >50% of ARVC patients 1
- Terminal activation delay (TAD) of QRS ≥55 ms in right precordial leads occurs in 34% of patients 2
- While not highly specific, signal-averaged ECG provides a marker of slow conduction and arrhythmic risk 1
Arrhythmic Manifestations
- Ventricular arrhythmias with left bundle branch block morphology and superior axis are typical of ARVC 1
- Premature ventricular contractions, ventricular tachycardia, and ventricular fibrillation may occur 1
- Left bundle branch block morphology with inferior axis requires differentiation from benign right ventricular outflow tract tachycardia 1
Dynamic ECG Changes
Serial ECGs are critical because 23-39% of ARVC patients demonstrate dynamic or new ECG abnormalities during follow-up 2, 5:
- New or dynamic T-wave inversion develops in approximately 10-13% of patients 2, 5
- Epsilon waves can appear, disappear, or fluctuate dynamically 2, 5
- These changes may occur before major structural abnormalities are detectable on imaging 5
Critical Clinical Considerations
Normal ECG Does Not Exclude ARVC
- Approximately 10% of ARVC patients present with a completely normal ECG 6
- A diagnosis based solely on imaging criteria with a completely normal ECG should be considered suspicious and warrants careful review 1
- Normal ECGs are mostly associated with mild or early forms of disease 3
- ECG changes are often the first disease manifestation, preceding structural abnormalities 1
Differential Diagnosis Pitfalls
- Distinguish epsilon waves from benign terminal QRS notching seen in early repolarization patterns 4
- Differentiate from right ventricular outflow tract tachycardia, which lacks the ECG abnormalities of ARVC and is more common in women 1
- Consider technical factors such as precordial lead misplacement that can affect R-wave progression 7
- Rule out other conditions mimicking ARVC including sarcoidosis, myocarditis, and athletic cardiac adaptation 8