PROGNOSTIC IMPACT OF SIGNAL-AVERAGED ECG IN NONISCHEMIC DILATED CARDIOMYOPATHY WITH SPONTANEOUS AND INDUCIBLE VENTRICULAR TACHYARRHYTHMIAS

Ventricular late potentials in signal-averaged ECG are a predictor of ventricular tachyarrhythmias in patients with coronary artery disease; The role of signal-averaged ECG in nonischemic dilated cardiomyopathy has not been defined yet. We studied the prognostic impact of an abno rmal signal-averaged ECG in 31 patients with non-ischemic dilated card iomyopathy. All signal-averaged ECG recordings were analyzed by time-d omain analysis as well as by frequency analysis with spectrotemporal m apping. Results: In 13 (42%) patients time domain analysis and in 9 (2 9%) patients frequency analysis was found to be abnormal. During follo w-up (13 +/- 7 months) seven (23%) patients developed spontaneous vent ricular tachyarrhythmias. The mean ejection fraction and the results o f programmed ventricular stimulation did not differ significantly betw een patients with and without clinical episodes. Abnormal time domain analysis was found in five (71%) patients with and in eight (33%) pati ents without spontaneous tachyarrhythmias (p = 0.07), and abnormal fre quency analysis in 3 (43%) patients versus 6 (25%) patients (p = 0.36) . The low-amplitude-signal duration was significantly increased in pat ients with tachyarrhythmias (p = 0.008). Ventricular tachyarrhythmias occurred in 38% of patients with abnormal time domain analysis and in 33% of patients with abnormal frequency analysis. In patients with nor mal signal-averaged ECG the incidence reached 11% and 18%. For time-do main analysis the sensitivity was 71%, specificity 67%, positive predi ctive value 38%, and negative predictive value 89%, for spectrotempora l mapping 33%, 75%, 33%, and 82%, respectively. The incidence of elect rophysiologically inducible ventricular tachyarrhythmias in patients w ith abnormal signal-averaged ECG exceeded that in patients with normal findings. Conclusion: In patients with non-ischemic dilated cardiomyo pathy a normal signal-averaged ECG is associated with a reduced occurr ence of ventricular tachyarrhythmic events. Thus, signal-averaged ECG contributes to the evaluation of these patients. The negative predicti ve value exceeded the positive predictive value.