Effects of a New Angiotensin-Converting Enzyme Inhibitor (Idrapril) in Rats with Left Ventricular Dysfunction After Myocardial Infarction

We evaluated the effects of a new angiotensin-converting enzyme (ACE) inhibitor (idrapril) in terms of hemodynamics and ventricular remodeling after myocardial infarction in rats. The animals were randomly assigned to four experimental groups. Myocardial infarction was induced by left coronary artery ligation in the first two groups treated with either idrapril (300 mg kg-1 day-1) or vehicle for 4 weeks after myocardial infarction. Two groups of sham-operated rats were treated accordingly. Hemodynamics were measured, and the diastole-arrested hearts were analyzed morphometrically to quantify left ventricular (LV) remodeling and infarct size. In infarcted rats, idrapril reduced the arterial systolic blood pressure (SBP) from 128 +/- 10 to 97 +/- 6 mm Hg (p < 0.05) and LV end-diastolic pressure (LVEDP) from 19 +/- 3 to 13 +/- 3 mm Hg (p < 0.01). The decrease in diastolic wall stress conferred by idrapril to infarcted rats (from 499 +/- 99 to 269 +/- 68 dynes mm-2, p < 0.05) was mainly due to a reduction in LVEDP and, to a lesser extent, in LV volume. Idrapril also reduced body and heart weights as compared with those of vehicle-treated animals. Four-week treatment with idrapril initiated immediately after myocardial infarction reduced LVEDP and limited LV wall stress, a major prognostic factor for the progression toward chronic ventricular failure.