VALUE OF TIME-DOMAIN AND FREQUENCY-DOMAIN ANALYSIS OF SIGNAL-AVERAGEDELECTROCARDIOGRAPHY FOR ARRHYTHMIA RISK PREDICTION IN IDIOPATHIC DILATED CARDIOMYOPATHY

Signal-averaged electrocardiography (SAECG) was performed in 120 conse cutive patients with idiopathic dilated cardiomyopathy (IDC), and in 6 0 healthy controls. Time-domain analysis of SAECGs revealed ventricula r late potentials in 27 of 120 patients with IDC (23%) compared to 2 o f 60 controls (3%; P < 0.05). Frequency-domain analysis of SAECGs show ed ventricular late potentials in 9 of 220 patients with IDC (8%) comp ared to none of the 60 controls (0%, P < 0.05). During a prospective f ollow-up of 15 +/- 7 months, serious arrhythmic events, defined as sus tained ventricular tachyarrhythmias or sudden death, occurred in 27 of 220 patients with IDC (14%). The sensitivity, specificity, and positi ve and negative predictive values of ventricular late potentials for s erious arrhythmic events were 35%, 80%, 22%, and 88% for the time-doma in analysis, and 18%, 94%, 33%, and 87% for the frequency-domain analy sis of SAECG, respectively. Th us, neither the time- nor the frequency -domain analysis of SAECG appears to be useful for risk stratification in the setting of IDC in view of their low sensitivity and low positi ve predictive value for serious arrhythmic events during follow-up.