Background: This study was done to determine whether the difference in duration of action of the long-acting angiotensin-converting enzyme (ACE) inhibitor spirapril compared with the short-acting ACE inhibitor captopril affects clinical efficacy in patients with congestive heart failure.
Methods and results: The effects on exercise capacity, neurohumoral status, and quality of life were studied in 20 patients with mild to moderate congestive heart failure in a double-blind, randomized, comparative study in parallel groups with a duration of 12 weeks. All assessments during the study were performed in the morning, before intake of the study medication, to avoid the expected peak effect of the ACE inhibitors used. Mean peak oxygen consumption (peak Vo2) was 17.4 mL/min/kg (range, 14.2-19.9 mL/min/kg) and mean left ventricular ejection fraction was 28% (range, 13-40%). Exercise duration in the captopril group showed a significant increase after 12 weeks (P < .05) of treatment compared with the spirapril group. Peak oxygen consumption tended only to increase in the captopril-treated patients compared with the spirapril-treated patients. Serum ACE activity was significantly different between the two treatment groups during treatment (P < .0001) and showed only a significant decrease in the spirapril group. There was no difference in improvement of quality of life between the two treatment groups.
Conclusions: This study showed that the effects of the ACE inhibitors spirapril and captopril on exercise capacity are not related to the degree of inhibition of serum ACE activity.