Summary:It is known from experiments that angiotensinconverting enzyme inhibitors can limit infarct size. In a prospective. randomized, placebo-controlled double-blind study, 22 patients were given 1.5-2.0 mg captoprilh I.V., while 24 patients were given placebo. Medication was started between 2 and I8 h from the onset of infarction. The two groups were matched for age, infarct location, and time of intervention. With the exception of one patient in either group, all were concurrently given nitroglycerin. The necrosis parameters were provided by the quantitative measurement of the QRS complex. The Q wave decreased with captopril treatment (-0.003 mV), but increased with placebo (+0.14 mV, p < 0.05). The number of ventricular premature beats at 24 h from the start of treatment was 2 5 h with placebo, and 9/h with captopril (p < 0.02). Ventricular fibrillation occurred seven times in the placebo group, but did not occur in the captopril group. The creatine kinase infarct weight was 59 gram-equivalents (gEq) with placrebo, and 45 gEq with captopril (p = NS). Mean arterial pressure was reduced by 12 mmHg with captopril treatment. The results show a beneficial effect of captopril on infarct size and electrical instability, over and above the effect of standard management with nitroglycerin and thrombolysis.

The effect of captopril on infarct size and arrhythmias was determined in a prospective, randomized, placebo-controlled double-blind study of 46 patients (9 women, 37 men; mean age 61 [38-86] years). Within 2-18 hours of entry into the study these patients received either a slow intravenous bolus injection of 2.5 or 5.0 mg captopril followed by a continuous infusion of 1.5-2.0 mg/h for a period of 48 hours (n = 22), or of a placebo by the same mode of administration (n = 24). The two groups were comparable as to age, infarct site and time of intervention. All patients, except one in each group, also received nitroglycerin (1.2-6.0 mg/h intravenously). QRS complexes were measured to provide a necrosis index. Q-wave amplitudes decreased under captopril (-0.08 +/- 0.04 mV) while increasing under placebo (+0.15 +/- 0.04 mV; P less than 0.05). The number of ventricular extrasystoles in the first 24 hours after onset of treatment or on placebo was 25/h and 9/h, respectively (P less than 0.02). Ventricular fibrillation occurred in 7 patients of the placebo group, in none of the captopril group. Creatine-kinase infarct weight was 59 and 45 gram-equivalents, respectively (placebo vs treated group: not significant). The mean arterial blood pressure fell by 14 mm Hg during the first hour in the captopril group, but by only 3 mm Hg on placebo (P less than 0.01). These results indicate that captopril has a favourable influence on infarct size and electrical stability which is additional to that provided by standard nitroglycerin treatment.