Angiotensin-converting enzyme inhibitors and beta-blockers in long-term treatment of dilated cardiomyopathy.

This double-blind, randomized, long-term study investigated the effects of the angiotensin-converting enzyme inhibitor enalapril and the beta-blocker metoprolol on clinical, hemodynamic, angiographic, and neurohormonal parameters in patients with dilated cardiomyopathy and moderate cardiac functional impairment (left ventricular ejection fraction [LVEF] 35% +/- 6%). After 12 months of treatment, a 12% reduction in 24-hour heart rate was observed in both groups (p < 0.05), whereas heart rate during exercise was reduced only in the metoprolol group. Echocardiographic fractional shortening increased (enalapril: 17% +/- 6% to 21% +/- 7%; metoprolol: 21% +/- 9% to 29% +/- 7%; both p < 0.05), as did the angiographic LVEF (enalapril: 35% +/- 7% to 43% +/- 12%, p = 0.1; metoprolol: 34% +/- 7% to 44% +/- 9%, p < 0.05), whereas ventricular volume decreased. Initially, both groups were comparable in terms of all parameters investigated. After 12 months fractional shortening was greater, and the heart rate at 50 W was lower in the beta-blocker group. At the doses used, the effect of the beta-blocker on dilated cardiomyopathy with moderate functional impairment was at least as great as that of the angiotensin-converting enzyme inhibitor.