Value of quantitative measurement of signal-averaged electrocardiographic variables in arrhythmogenic right ventricular dysplasia: correlation with echocardiographic right ventricular cavity dimensions.

OBJECTIVES: We sought to investigate the relation between signal-averaged electrocardiographic (ECG) variables and the extent of right ventricular disease, as estimated by right ventricular enlargement during detailed echocardiography, in patients with arrhythmogenic right ventricular dysplasia.

BACKGROUND: In patients with ventricular tachycardia of right ventricular origin, a normal signal-averaged ECG is indicative of "idiopathic" ventricular tachycardia, whereas an abnormal signal-averaged ECG is a specific marker for right ventricular disease, especially dysplasia. Signal-averaged ECGs in these patients are mildly to grossly abnormal.

METHODS: Ten patients with the clinical diagnosis of arrhythmogenic right ventricular dysplasia were included. All patients had documented, sustained ventricular tachycardia, no coronary artery disease and a normal QRS duration of < or = 110 ms on routine 12-lead electrocardiography. Signal-averaged ECGs were recorded using time-domain analysis. Right ventricular cavity dimensions recorded during two-dimensional echocardiography were measured at the level of the inflow tract, midcavity and outflow tract. Signal-averaged ECG variables and echocardiographic measurements were correlated using linear regression analysis.

RESULTS: Nine of 10 patients had abnormal signal-averaged ECGs. There was a consistent correlation between all signal-averaged ECG variables and the right ventricular cavity dimensions at the level of the midcavity. The correlation was most significant with the duration of the filtered QRS complex (p < 0.001 for QRS duration, p < 0.01 for late potential duration and p < 0.05 for root-mean-square voltage of the last 40 ms). There was no consistent correlation between the signal-averaged ECG variables and right ventricular dimensions at the level of the inflow and outflow tracts.

CONCLUSIONS: The majority of patients with arrhythmogenic right ventricular dysplasia have abnormal signal-averaged ECGs. In the absence of bundle branch block, the extent of abnormality of signal-averaged ECG variables is in proportion to right ventricular cavity enlargement, and thus is indicative of the severity of right ventricular dysfunction.