Idiopathic dilated cardiomyopathy: prognostic significance of electrocardiographic and electrophysiologic findings in the nineties.

Background: With the exception of a few cases such as aborted sudden cardiac death, sustained ventricular tachycardia, and syncope of unexplained origin, there is no consensus on the clinical findings identifying patients with idiopathic dilated cardiomyopathy with an increased risk of sudden cardiac death or malignant ventricular arrhythmias.

Methods: To verify whether electrocardiographic and arrhythmologic features could be useful for prognostic stratification, 78 consecutive patients with an invasive diagnosis of idiopathic dilated cardiomyopathy, but without symptomatic ventricular arrhythmias, were enrolled in a prospective study. Signal-averaged ECG, 24 to 48 hour ECG monitoring and electrophysiologic study were performed at the time of diagnosis to identify arrhythmogenic predictors of outcome. Transplant-free and arrhythmic event-free survival was evaluated on the basis of initial parameters.

Results: During a mean follow-up of 85 months, 9 patients died (6 of sudden cardiac death and 3 of congestive heart failure), 10 patients underwent cardiac transplantation for refractory heart failure, and 3 presented with sustained ventricular tachycardia. The independent predictors for death and cardiac transplantation were an HV interval > 55 ms and the combination of frequent repetitive ventricular ectopics with a poor left ventricular function. A strong index of arrhythmic events proved to be the association of a prolonged HV interval with a wide (> 110 ms) QRS complex (odds ratio 4.53, 95% confidence interval 1.57-13.04, p < 0.005).

Conclusions: An accurate measurement of the HV interval and QRS duration at baseline evaluation may add prognostic information in patients with idiopathic dilated cardiomyopathy. In our experience, abnormal values of both parameters identified a group of patients with a very high risk of late occurring arrhythmic events.