Long-Term Anti-Ischemic Effects of Angiotensin-Converting Enzyme Inhibition in Patients After Myocardial Infarction

Objectives. This study was conducted to test the hypothesis that angiotensin-converting enzyme (ACE) inhibition reduces myocardial ischemi and related events after myocardial infarction (MI). Background. The oxygen demand/supply ratio of the myocardium is influenced by angiotensin II as result of its arterial vasoconstrictive and inotropic effects and through its interaction with the sympathetic nervous system. Methods. We studied 244 patients who had been included in double-blind, randomized, placebo-controlled, post-MI, ACE inhibition intervention study (Captopril and Thrombolysis Study [CATS]). All patients underwent exercise testing before and 3 and 12 months after hospital discharge. After 1-year double-blind treatment, all patients continued receiving single-blind placebo for 1 month. Results. Total exercise time increased in both groups after 3 months (placebo: +86 ± 13 s; captopril: +69 ± 12 s, p = 0.8 between groups) and increased further after 1 year (placebo: +13 ± 11 s; captopril: +33 ± 13 s, p = 0.7 between groups). There were also no differences in mean ST segment depression. During the 12 months, significantly fewer ischemia-related events occurred in the captopril group (82 vs. 52, p = 0.015). This difference was found between 3 and 12 months but not during the first 3 months. After withdrawal from double-blind medication, nine ischemic events were reported in the captopril group compared with one in the placebo group (p = 0.006 between groups). Conclusions. The present dat show that captopril may reduce the incidence of ischemia-related events after MI, which becomes apparent after 3 months. However, no anti-ischemic effect was observed during exercise testing. After withdrawal from ACE inhibition, high incidence of clinical events occurred, suggesting rebound phenomenon.