EFFECTS OF CAPTOPRIL ON VENTRICULAR ARRHYTHMIAS IN THE EARLY AND LATE-PHASE OF SUSPECTED ACUTE MYOCARDIAL-INFARCTION - RANDOMIZED, PLACEBO-CONTROLLED SUBSTUDY OF ISIS-4

The antiarrhythmic effect of oral captopril was studied during the ear ly (day 3) and late (day 14) phase of acute myocardial infarction amon g 304 patients in a randomized placebo-controlled substudy of ISIS-4. Ventricular arrhythmias (ventricular ectopic beats per hour) occurred significantly less frequently among captopril-allocated patients than among those allocated placebo al day 3 (logarithmic scale: 0 . 48+/-0 . 8 captopril vs 0 . 84+/-1 . 3 placebo; P<0 . 003) and at day 14 (0 . 51+/-1 . 0 vs 0 . 77+/-1 . 3; P<0 . 05). The number of patients with frequent ventricular arrhythmias (more than 10 ventricular ectopic bea ts per hour) was also significantly lower among those allocated captop ril at day 3 (7 . 3% vs 14 . 4%; P<0 . 05) and at day 14 (7 . 3% vs 14 . 8%; P<0 . 05). These results support the hypothesis that the activa tion of the renin-angiotensin-aldosterone and sympathetic system may u nderlie heart rhythm disturbances in acute myocardial infarction, and that early use of converting enzyme inhibitor therapy may ameliorate t hese disturbances.