Effect of enalapril on myocardial infarction and unstable angina in patients with low ejection fractions

Abstract

An association between raised renin levels and myocardial infarction has been reported. We studied the effects of enalapril, an angiotensin-converting enzyme (ACE) inhibitor, on the development of myocardial infarction and unstable angina in 6797 patients with ejection fractions ≤0·35 enrolled into the two Studies of Left Ventricular Dysfunction (SOLVD) trials. Patients were randomly assigned to placebo (n=3401) or enalapril (n=3396) at doses of 2·5-20 mg per day in two concurrent double-blind trials with the same protocol. Patients with heart failure entered the treatment trial (n=2569) and those without heart failure entered the prevention trial (n=4228). Follow-up averaged 40 months. In each trial there were significant reductions in the number of patients developing myocardial infarction (treatment trial: 158 placebo vs 127 enalapril, P<0·02; prevention trial: 204 vs 161 p<0·01) or unstable angina (240 vs 187 p<0·001; 355 vs 312, p<0·05). Combined, there were 362 placebo group patients with myocardial infarction compared with 288 in the enalapril group (risk reduction 23%, 95% Cl 11-34%; p<0·001). 595 placebo group patients developed unstable angina compared with 499 in the enalapril group (risk reduction 20%, 95% Cl 9-29%, p<0·001). There was also a reduction in cardiac deaths (711 placebo, 615 enalapril; P<0·003), so that the reduction in the combined endpoint of deaths, myocardial infarction, and unstable angina was highly significant (20% risk reduction, 95% Cl 14-26%; p<0·0001). Enalapril treatment significantly reduced myocardial infarction, unstable angina, and cardiac mortality in patients with low ejection fractions.