Signal-averaged electrocardiography in patients with nonischemic dilated cardiomyopathies

Patients with nonischemic dilated cardiomyopathies (NIDCM) are at high risk for sudden death. Resting hemodynamic measurements, Holter monitoring, and electrophysiologic testing do not reliably stratify these patients according to risk. Signal-averaged electrocardiography provides a valuable noninvasive tool for identifying those individuals at greatest risk for ventricular tachyarrhythmias. The technique can detect delayed and disorganized ventricular activation in regions of myocardial scarring that constitute the substrate for ventricular tachycardia. The incidence of sudden death; potential mechanisms of sudden death, and the application of Holter monitoring, programmed electrical stimulation, and signal-averaged electrocardiography to the risk stratification of patients with NIDCM are discussed.