Determinants of prognosis in idiopathic dilated cardiomyopathy as determined by programmed electrical stimulation

Abstract

The incidence and prognostic significance of electrically induced ventricular arrhythmias were prospectively assessed in 42 patients with idiopathic dilated cardiomyopathy. All patients underwent 24-hour, long-term electrocardiographic (Holter) monitoring and 30 were analyzed by a signal-averaging vectorcardiographic procedure at entry into the study. Their response to programmed electrical stimulation during basic right ventricular pacing was investigated using 1 and 2 ventricular extrastimuli. A monomorphic tachycardia was not induced in any patient. In 36 patients (86%) polymorphic ventricular arrhythmias were initiated. Three or more induced consecutive ventricular premature complexes occurred in 9 patients (21%), nonsustained polymorphic ventricular tachycardia in 2 (4.8%) and ventricular fibrillation in 1 patient (2.4%). There was no association between electrically induced polymorphic ventricular arrhythmias and the degree of impairment of left ventricular function. Furthermore, the incidence of induced ventricular arrhythmias was not related to the Lown grade or to the total number of ventricular premature complexes during Holter monitoring. A late potential was detected by the averaged vectorcardiogram in only 1 of the 30 patients. During follow-up (mean 16 ± 7 months) 7 patients died, 5 from chronic congestive heart failure and 2 from sudden cardiac death. No patient had an electrically induced arrhythmia of 3 or more ventricular premature complexes. Thus, in most patients with idiopathic dilated cardiomyopathy, programmed electrical stimulation of the right ventricle with up to 2 extrastimuli fails to reproduce an electrophysiologic correlate to the frequent ventricular arrhythmias.