Ventricular remodeling after myocardial infarction and effects of ACE inhibition on hemodynamics and scar formation in SHR.
The effect of ACE inhibition after myocardial infarction (MI) on MI healing and remodeling in the presence of hypertension is not exactly known. Therefore, the effect of quinapril on scar formation, remodeling and hemodynamics was studied in spontaneously hypertensive rats (SHR). Nine weeks after moderate and large MI, left ventricular end-diastolic pressure (LVEDP) and passive pressure-volume relations were similar in 28-week-old hypertensive and normotensive rats. Chronic therapy with quinapril (6 mg/kg/day, started 30 min post-MI) reduced LVEDP and LV to body weight ratio, yet did not affect pressure-volume relations. Quinapril increased MI size and reduced the content and brightness of collagen fibers in the scar examined by polarized light microscopy. In conclusion, ventricular dilatation after MI was not accelerated in SHR, probably due to LV hypertrophy. Quinapril produced beneficial hemodynamic effects similar to that observed in the normotensive rat model. The significance and timing of ACE inhibitor-induced impairment of scar formation need further evaluation.