Does time- and frequency-domain analysis of signal-averaged electrocardiography predict serious arrhythmic events in patients with idiopathic dilated cardiomyopathy?
Neither time- nor frequency-domain analysis of signal-averaged electrocardiography is useful for arrhythmia risk stratification in idiopathic dilated cardiomyopathy due to low sensitivity and positive predictive value.
Signal-averaged electrocardiography (SAECG) was performed in 120 consecutive patients with idiopathic dilated cardiomyopathy (IDC), and in 60 healthy controls. Time-domain analysis of SAECGs revealed ventricular late potentials in 27 of 120 patients with IDC (23%) compared to 2 of 60 controls (3%; P < 0.05). Frequency-domain analysis of SAECGs showed ventricular late potentials in 9 of 120 patients with IDC (8%) compared to none of the 60 controls (0%, P < 0.05). During a prospective follow-up of 15 +/- 7 months, serious arrhythmic events, defined as sustained ventricular tachyarrhythmias or sudden death, occurred in 17 of 120 patients with IDC (14%). The sensitivity, specificity, and positive and negative predictive values of ventricular late potentials for serious arrhythmic events were 35%, 80%, 22%, and 88% for the time-domain analysis, and 18%, 94%, 33%, and 87% for the frequency-domain analysis of SAECG, respectively. Thus, 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 positive predictive value for serious arrhythmic events during follow-up.
Grimm et al. (1996) studied this question.