EFFECT OF EARLY ENALAPRIL THERAPY ON LEFT-VENTRICULAR FUNCTION AND STRUCTURE IN ACUTE MYOCARDIAL-INFARCTION

Infarct expansion starts within hours to days after transmural myocard ial injury. Previous echocardiographic and left ventriculographic stud ies demonstrated that angiotensin-converting enzyme (ACE) inhibitor th erapy limits left ventricular dilatation, particularly in patients wit h anterior wall acute myocardial infarction (AMI) or impaired left ven tricular function. Forty-three patients with an acute Q-wave AMI were randomized within 24 hours of symptom onset to intravenous enalaprilat (1 mg) or placebo. Patients were then given corresponding oral therap y and followed for 1 month. Predrug and 1-month gated blood pool scans were obtained in 32 patients to evaluate changes in cardiac volumes a nd ejection fraction. Twenty-three patients underwent magnetic resonan ce imaging at 1 month to evaluate left ventricular infarct expansion. Blood pressure decreased at 6 hours but returned to baseline in both g roups after 1 month of therapy. The change in cardiac volumes from bas eline to 1 month differed between the placebo (end-diastolic volume +1 6 +/- 5 ml, end-systolic volume +8 +/- 6 ml), and enalapril (end-diast olic volume -8 +/- 9 ml and end-systolic volume -14 +/- 7 ml) groups ( p <0.05 vs placebo). Global and infarct zone ejection fractions improv ed significantly at 1 month in the enalapril group (+6 +/- 3% and 19 /- 5%, respectively) but did not change over 1 month in the placebo gr oup. Infarct segment length and infarct expansion index by magnetic re sonance Imaging were significantly less in those treated with enalapri l, suggesting less infarct expansion in this group. Thus, early admini stration of enalaprilat to patients presenting with a first Q-wave AMI prevents cardiac dilatation and infarct expansion.