The Studies of Left Ventricular Dysfunction (SOLVD) prevention trial evaluated 4,228 patients with a left ventricular ejection fraction < or = 35% who were not receiving drug therapy for heart failure. Patients were randomized to treatment with enalapril or placebo in a dose of 2.5 to 20 mg/day. Patients randomized to enalapril showed a 37% reduction in the development of heart failure and a 36% reduction in hospitalization for heart failure (p < or = 0.001). However, there was only an 8% reduction in total mortality and a 14% reduction in cardiovascular mortality (p = NS). On the basis of the SOLVD prevention trial, patients with asymptomatic left ventricular dysfunction due to either ischemic or nonischemic cardiomyopathy should be started on treatment with an angiotensin-converting enzyme inhibitor to prevent the development of and hospitalization for heart failure.