ARVD should be suspected in a young or middle aged person who has ventricular arrhythmias with left bundle branch block morphology and who does not have other cardiac disease. Presentation as right ventricular failure is uncommon. A 12-lead electrocardiogram should be carefully examined for
1) T wave inversion beyond lead V1
2) epsilon waves, which are reproducible small deflections seen just beyond
the QRS complex in lead V1 or V2.
3) Right ventricular parietal block as evidenced by a QRS duration
in V1
+ V2 + V3 that is longer than that in leads V4,
V5, V6 by a ratio of 1:2.
The sensitivity to detect these ECG abnormalities is enhanced by careful skin preparation to eliminate artifacts and by recording the electrocardiogram at double speed (50 mm/second) and double the usual amplitude (20 mm/mvolts). ECG protocol
The major differential diagnosis in a patient who has left ventricular arrhythmias of left bundle block morphology with a configuration of inferior QRS axis (negative QRS in lead AVL) is that of right ventricular outflow tract (RVOT) tachycardia. Patients with RVOT tachycardia do not usually have the ECG abnormalities associated with ARVD and the signal-averaged electrocardiogram is generally normal. They may have some dilatation and decrease in contractility limited to the right ventricular outflow tract.
It is important to determine if the patient has ARVD or RVOT tachycardia for two reasons. First, the prognosis of the two conditions is different. RVOT tachycardia has an excellent prognosis and seldom results in arrhythmic death. In contrast, there is a risk of sudden death as great as 1% per year in patients with ARVD who have ventricular arrhythmias. Secondly, ARVD may be hereditary whereas RVOT tachycardia is not. Therefore, when the diagnosis of ARVD is made, it is recommended that first degree relatives (parents, brothers, sisters, and children of the affected person) be evaluated for presence of this condition in order to prevent the unusual occurrence of arrhythmic death in family members.