Significance of ventricular arrhythmias in idiopathic dilated cardiomyopathy

Abstract

The incidence and prognostic Significance of ventricular arrhythmias identified by 24-hour ambulatory electrocardiography (Holter) was prospectively assessed in 74 patients with idiopathic dilated cardiomyopathy (IDC). The criteria for diagnosis of IDC were based on clinical and cardiac catheterization findings. Holter monitoring was performed at the time of entry into the study. Patients were followed for 2 to 21 months (mean 11 ± 3). Frequent ventricular premature complexes (VPCs) ( > 1,000 24 hours ) were seen in 35%, and complex VPCs (Lown grade III and IV) in 87 % of the patients. Forty-nine percent of the patients had nonsustained ventricular tachycardia (VT) consisting of 3 to 32 beats with rates from 110 to 230 beats/min, and 20% had ventricular pairs. No correlation was found between clinical symptoms or the degree of left ventricular (LV) impairment and the number of ventricular pairs or episodes of VT. During follow-up, 19 patients died, 7 from congestive heart failure (CHF) and 12 suddenly. Patients who died suddenly had significantly more episodes of VT, ventricular pairs or total VPCs (p <0.01 each) compared with survivors and those who died from CHF. No significant differences were found between patients who died from CHF or suddenly with respect to LV end-diastolic pressure, LV end-diastolic volume index, LV ejection fraction (EF) and cardiac index. A linear stepwise discriminant function analysis using hemodynamic (LVEF and cardiac index) and arrhythmic (number of VT episodes and ventricular pairs) variables resulted in a meaningful separation between survivors and patients who died from CHF or suddenly. Thus, patients with IDC and a reduced LVEF (<40%) in whom frequent episodes of VT or ventricular pairs were detected by 24-hour Holter monitoring are at high risk of dying suddenly.