TIME-DOMAIN AND FREQUENCY-DOMAIN ANALYSES OF THE SIGNAL-AVERAGED ECG IN PATIENTS WITH SUSTAINED VENTRICULAR TACHYARRHYTHMIA AND NONISCHEMIC HEART-DISEASES

Signal-averaged electrocardiogram (EGG) variables were analyzed in 81 patients with ventricular tachyarrhythmia and nonischemic heart disease using the ART LVP 101 EPX system (Austin, TX): 15 ventricular tachycardia patients with arrhythmogenic right ventricular dysplasia (ARVD), 7 ventricular tachycardia patients with dilated cardiomyopathy, 25 patients with ''idiopathic'' verapamil-sensitive left ventricular tachycardia, 24 patients with ''idiopathic'' right ventricular tachycardia, and 10 ''idiopathic'' ventricular fibrillation (IVF) patients with rbbb pattern and ST-segment elevation in the precordial leads. Data from 52 normal control subjects were also analyzed. The first study was to test the hypothesis of any difference in signal-averaged ECG indices between patients with ARVD and patients with dilated cardiomyopathy. Longer filtered QRS duration and T40 and higher amplitude of the terminal filtered QRS complex outside the end of the standard QRS complex (log V-outside) were noted in patients with ARVD (filtered QRS duration, 172 vs 144 ms, P < .05; T40, 94 vs 62 ms, P < .05; log V-outside, 1.48 vs 0.56, P < .01). Endocardial mapping showed noticeable extension of fractionated electrograms in the right ventricle and longer duration of fractionated intracardiac electrograms in patients with ARVD, which might explain the difference in signal-averaged ECG indices between these two diseases. The second study was to test the hypothesis of and the variables that can suggest the arrhythmogenic substrate in patients with idiopathic ventricular tachycardia. Signal-averaged ECG indices in time-domain and frequency-domain (fast Fourier transform method: area ratio, spectrotemporal mapping) analyses did not indicate any differences between patients with idiopathic ventricular tachycardia and normal control subjects. The third study was to test the hypothesis of any indices that suggest the arrhythmogenic substrate in patients with IVF. Time-domain analysis showed some difference between patients with IVF and normal control subjects (but not statistically significant because of a small number of patients with IVF).