Effects of long-term enalapril therapy on cardiopulmonary exercise performance after myocardial infarction

Abstract

Background. The Enalapril Postinfarction Exercise (EPIE) trial was designed to study the effect of enalapril treatment on peak and submaximal cardiopulmonary exercise performance over the course of 1 year in men after myocardial infarction with mild exercise intolerance. Methods and Results. One hundred sixty men with a peak Vo2 less than 25 ml/kg/min and without effort angina were randomized to receive enalapril 20 mg qd or placebo on a double-blind basis. The mean age was 60.3±7.6 years. All patients received concurrent β-blocker therapy for secondary prophylaxis. Treatment began at 21 days (group 1, n;=100) or more than 6 months after infarction (group 2, n=60). Patients underwent exercise with real-time gas-exchange analysis nine times over the course of 48 weeks. In group 1, improvement in exercise performance occurred during the course of the trial in both groups of patients receiving placebo or enalapril. The mean peak Vo2 for the placebo-treated patients in group 1 increased from 18.3±3.4 ml/kg/min by 4.9% at 48 weeks (p<0.05). The corresponding values for enalapril-treated patients were 18.9±3.8 ml/kg/min with a 3.7% increase (p=0.07). Total exercise time increased in the placebo-treated patients from 645±96 seconds by 7.3% (p<0.01). Corresponding values for enalapril-treated patients were 674±103 seconds with a 5.4% increase (p<0.01). In group 2, the mean peak V̇o2 at baseline for the placebo-treated patients of 20.3±3.8 ml/kg/min increased by 4.4% at 48 weeks (p=NS). The corresponding values for enalapril-treated patients were 19.2±3.6 ml/kg/min with a 2.6% increase (p=NS). Total exercise time increased in the placebo-treated patients from 677±114 seconds by 0.7% (p=NS). Corresponding values for enalapril-treated patients were 659±99 seconds with a 1.1% increase (p=NS). There were no significant differences between the placebo and enalapril subgroups at any time with regard to peak V̇o2, exercise duration, or the V̇o2 at the anaerobic threshold. Conclusions. This trial demonstrates that long-term converting enzyme inhibition with enalapril had no significant effect on the peak or submaximal cardiopulmonary exercise performance over the course of 1 year in men after myocardial infarction with only mildly reduced exercise capacity.