Enalapril in chronic heart failure, a double-blind placebo-controlled study.

The efficacy of enalapril, a new angiotensin-converting enzyme inhibitor, was investigated in a double-blind placebo-controlled study in 24 patients with chronic heart failure. The patients belonging to NYHA functional class II-IV and treated with digoxin and diuretics were randomized to enalapril (12 patients) or placebo (12 patients) treatment for a 12-week period. Assessments were carried out at baseline and at 4 and 12 weeks during the treatment period. Complete data could be obtained on 10 patients receiving enalapril and on 11 patients receiving placebo. NYHA functional class improved by at least one class in 6 of 10 patients in the enalapril group, but only in 1 of 11 patients in the placebo group (chi 2 = 6.54; p less than 0.05). Duration of bicycle ergometer exercise increased significantly in the enalapril group from 8.8 +/- 3.4 to 11.3 +/- 4.2 (4 weeks) and to 11.2 +/- 3.6 min (12 weeks; p less than 0.05 for both), whereas it remained unchanged in the placebo group. Left ventricular ejection fraction by radionuclide ventriculography in the enalapril group increased significantly (baseline: 33.5 +/- 19.9%, 4 weeks: 40.0 +/- 20.0% (p less than 0.001), 12 weeks: 39.6 +/- 20.1% (p less than 0.01], whereas in the placebo group it did not change significantly from the baseline of 48.8 +/- 16.7%. The results indicate that enalapril induces a sustained relief of symptoms and improves exercise capacity in patients with heart failure. This subjective improvement appears to be accompanied by an increase in ejection fraction.