Characteristic ECG Findings in ARVD
The ECG in ARVD characteristically shows precordial T-wave inversion (typically V1-V3), epsilon waves (low voltage potentials following the QRS), QRS duration >110 ms, and ventricular arrhythmias with left bundle branch block morphology. 1
Key Depolarization Abnormalities
The depolarization changes reflect the underlying fibro-fatty replacement of myocardium and slow conduction through diseased tissue:
Epsilon waves: Characteristic low-voltage potentials appearing after the QRS complex, representing delayed activation of diseased right ventricular myocardium. These are pathognomonic but seen relatively infrequently 1, 2
Prolonged terminal activation duration: QRS duration >110 ms in right precordial leads, reflecting slow depolarization through the diseased RV 3
QRS fragmentation: Predicts adverse outcomes and reflects heterogeneous myocardial activation 4
Low QRS amplitude: Reduced voltage in limb leads may be present 5
Repolarization Abnormalities
T-wave inversion in V1-V3 is the most sensitive and specific ECG finding, present in approximately 71% of ARVD patients without bundle branch block 2. This finding reflects scarring of the RV free wall 6:
In patients without complete or incomplete RBBB: T-wave inversion through V3 demonstrates optimal sensitivity (71%) and specificity (96%) 2
Extension beyond V3: T-wave inversion extending to V4-V6 or into inferior leads (II, III, aVF) suggests more extensive disease, including left ventricular involvement 5
T-wave inversion in inferior leads independently predicts major adverse cardiovascular events 4
Ventricular Arrhythmias
Up to two-thirds of patients demonstrate ventricular arrhythmias on resting or ambulatory monitoring 7:
Left bundle branch block morphology with superior axis (negative in leads II, III, aVL) is typical of RV origin 5, 1
Critical distinction: LBBB morphology with inferior axis (positive in II, III) requires differentiation from benign RVOT tachycardia, which is not familial and rarely life-threatening 5
Multiple QRS morphologies during VT are common 7
Special Considerations with Bundle Branch Block
In patients with complete RBBB (present in ~17% of ARVD patients), standard criteria lose diagnostic utility 2:
Most useful parameter: r'/s ratio in V1 <1 (sensitivity 88%, specificity 86%) 2
T-wave inversion through V4 (rather than V3) becomes the relevant repolarization criterion (59% vs 12% in controls) 2
Left Ventricular Involvement
When LV disease is present (>50% of patients) 7:
- Lateral/inferolateral T-wave inversion (V5, V6, I, aVL) 5
- Low voltage QRS in standard limb leads 5
- Ventricular arrhythmias may show patterns suggesting LV origin 5
Common Pitfalls
A completely normal ECG should raise suspicion about the diagnosis - while ~10% of ARVD patients may have normal ECGs 3, an AC diagnosis based solely on imaging criteria with entirely normal ECG warrants careful review 5. ECG changes typically precede overt structural abnormalities 5.
The ECG abnormalities are most prominent in anterior chest leads (V1-V4) due to the proximity of the RV to these leads 6. Signal-averaged ECG showing late potentials is present in >50% of patients but lacks sufficient sensitivity and specificity for diagnosis 1.
Risk Stratification Value
Specific ECG parameters predict adverse outcomes 4:
- Precordial QRS amplitude ratio ≤0.48 (∑QRS V1-V3/∑QRS V1-V6)
- Inferior lead T-wave inversions
- QRS fragmentation
- Extent of T-wave inversion
These findings correlate with disease severity and help identify high-risk patients requiring closer monitoring or ICD consideration 4.