Effects of long-term beta-blockade (metoprolol) therapy in patients with dilated cardiomyopathy.

Twenty-two patients with dilated cardiomyopathy (DCM) were treated with metoprolol and their clinical courses were compared with those of 26 patients untreated with beta-blocking agents (non beta group). Of the 22 patients treated with metoprolol, 19 (beta group) were treated for a long period, 3 patients left the study within its first 6 months. Using the NYHA classification, 4 patients of the beta group were evaluated as having clinically improved, while none was aggravated, excluding 2 cases of death which occurred during the follow up period. In the non-beta group, clinical improvement was found for 2 patients and aggravation in functional class for 10. The left ventricular diameter was significantly decreased and parameters of systolic function and exercise tolerance were significantly improved in patients of the beta group, while no such improvements occurred in patients of the non-beta group. Twenty-four-hour ECG monitoring demonstrated a significant reduction in incidences of ventricular extrasystole in the beta group but not in those of the non-beta group. Improvement of arrhythmias, evaluated using Lown's grading system, was also identified more frequently in the beta group than in the non-beta group. During the follow-up period, 2 patients of the beta group and 10 patients of the non-beta group died. The survival curve for patients of the beta group prepared using the Caplan Meier Method was better than that for patients of the non-beta group. Metoprolol was therefore found to be useful for treatment of DCM.