First- or second-degree atrioventricular block as a risk factor in idiopathic dilated cardiomyopathy.

To evaluate the significance of clinical, hemodynamic and electrocardiographic risk factors in idiopathic dilated cardiomyopathy 94 patients were followed prospectively for 49 +/- 37 months. During follow-up, 30 patients died, 13 died suddenly, 13 died of congestive heart failure and 4 of other causes. Follow-up was completed in 85 patients, and overall cardiac mortality was 31%. Univariate analysis revealed left ventricular ejection fraction among 20 variables as the major indicator of risk of both cardiac death of all causes and sudden cardiac death separately. Multivariate overall analysis determined 3 independent risk factors in the following order for all causes of cardiac death: Ventricular pairs > 40/24 hours (RR 7.2, p < 0.0001), left ventricular ejection fraction < or = 35% (RR 6.5, p < 0.001) and first- or second-degree atrioventricular (AV) block (RR 3.1, p < 0.05). In the subset of patients with ejection fraction < or = 35% ventricular pairs > 40 per 24 hours (RR 10.7, p < 0.001), AV block (RR 3.9, p < 0.05), and the missing administration of vasodilators (RR 3.3, p < 0.05) were the most important. The chief risk factors for sudden cardiac death were age (RR 7.4, p < 0.01) and AV block (RR 4.6, p < 0.05) by adjustment for age, and ejection fraction < or = 35% (RR 7.1, p < 0.01) and AV block (RR 4.2, p < 0.05) if not adjusted for age. A differentiation into 4 risk groups was attempted. The additional independent prognostic importance of AV block was shown, especially in combination with reduced ejection fraction or a high incidence of ventricular pairs.(ABSTRACT TRUNCATED AT 250 WORDS)