ELECTROCARDIOGRAPHIC AND MORPHOMETRIC FEATURES IN PATIENTS WITH VENTRICULAR-TACHYCARDIA OF RIGHT-VENTRICULAR ORIGIN

Objective-To study differences between repetitive monomorphic ventricu lar tachycardia (RMVT) of right ventricular origin, and ventricular ta chycardia in arrhythmogenic right ventricular dysplasia (ARVD). Patien ts-Consecutive groups with RMVT (n = 15) or ARVD (n = 12), comparable for age and function. Methods-Analysis of baseline, tachycardia, and s ignal averaged ECGs, clinical data, and right endomyocardial biopsies. Pathological findings were related to regional depolarisation (QRS wi dth) and repolarisation (QT interval, QT dispersion). Results-There wa s no difference in age, ejection fraction, QRS width in leads I, V1, a nd V6, and QT indices. During ventricular tachycardia, more patients w ith ARVD had a QS wave in V1 (P < 0.05). There were significant differ ences for unfiltered QRS, low amplitude signal duration, and the root mean square voltage content. In the absence of bundle branch block, di fferences became nonsignificant for unfiltered and filtered QRS durati on. Mean (SD) percentage of biopsy surface differed between RMVT and A RVD: normal myocytes (74(3.4)% v 64.5(9.3)%; p < 0.05); fibrosis (3(1. 7)% v 8.9(5.2)%; p < 0.05). When all patients were included, there wer e significant correlations between fibrosis and age (r = 0.6761), and fibrosis and QRS width (r = 0.5524 for lead I; r = 0.5254 for lead V1; and r = 0.6017 for lead V6). Conclusions-The ECG during tachycardia a nd signal averaging are helpful in discriminating between ARVD and RMV T patients. There are differences in the proportions of normal myocyte s and proportions of normal myocytes and fibrosis. The QRS duration is correlated with the amount of fibrous tissue in patients with ventric ular tachycardia of right ventricular origin.