EFFECTS OF CAPTOPRIL THERAPY AFTER LATE REPERFUSION ON LEFT-VENTRICULAR REMODELING AFTER EXPERIMENTAL MYOCARDIAL-INFARCTION

Reperfusion that is too late to salvage ischemic myocardium reduces ea rly infarct expansion, and captopril therapy favorably alters long-ter m left ventricular remodeling. To study whether the beneficial effects of these two therapies are additive, we examined the effects of capto pril therapy after late reperfusion on left ventricular remodeling aft er acute myocardial infarction. Female Sprague-Dawley rats (n = 67) we re randomly assigned to one of four groups: group 1, sham surgery and no treatment; group 2, left coronary artery ligation and no treatment (myocardial infarction r MI); group 3, left coronary artery ligation , reperfusion 2 hours later, and no treatment (late reperfusion LR); and group 4, left coronary artery ligation, reperfusion 2 hours later , and captopril treatment (LR-Cap). Captopril therapy (2 gm/L of drink ing water) was begun in the LR-Cap group in the immediate post-operati ve period and continued for 20 days. Twenty-one days postoperatively, hemodynamic measurements were made before and after volume loading. Th e rats were killed, their hearts were removed, and passive pressure-vo lume curves were obtained. The hearts were then fixed at a constant pr essure for morphometric analysis. Compared with the MI group, the LR g roup had a lower expansion index and a higher thinning ratio. There we re no differences in hemodynamics, left ventricular volumes, or other morphometric indexes between the two groups. Compared with the MI and LR groups, the LR-Cap group had lower peak left ventricular end-diasto lic pressure, lower left ventricular volume, lower left and right vent ricular weights, and a leftward shift of pressure-volume curves. There were no differences in the expansion index or the thinning ratio betw een the LR and LR-Cap groups. Thus captopril therapy after late reperf usion additionally improves hemodynamics, attenuates left ventricular cavity dilation, attenuates an increase in left and right ventricular weights, and alters the pressure-volume relationship of the left ventr icle.