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

Signal-averaged electrocardiogram (EGG) variables were analyzed in 81 patients with ventricular tachyarrhythmia and nonischemic heart diseas e using the ART LVP 101 EPX system (Austin, TX): 15 ventricular tachyc ardia patients with arrhythmogenic right ventricular dysplasia (ARVD), 7 ventricular tachycardia patients with dilated cardiomyopathy, 25 pa tients with ''idiopathic'' verapamil-sensitive left ventricular tachyc ardia, 24 patients with ''idiopathic'' right ventricular tachycardia, and 10 ''idiopathic'' ventricular fibrillation (IVF) patients with rbb b 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 b etween patients with ARVD and patients with dilated cardiomyopathy. Lo nger filtered QRS duration and T40 and higher amplitude of the termina l filtered QRS complex outside the end of the standard QRS complex (lo g 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 t hese two diseases. The second study was to test the hypothesis of and the variables that can suggest the arrhythmogenic substrate in patient s with idiopathic ventricular tachycardia. Signal-averaged ECG indices in time-domain and frequency-domain (fast Fourier transform method: a rea ratio, spectrotemporal mapping) analyses did not indicate any diff erences between patients with idiopathic ventricular tachycardia and n ormal 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 wit h IVF and normal control subjects (but not statistically significant b ecause of a small number of patients with IVF).