Effect of a selective aldosterone receptor antagonist in myocardial infarction

Myocardial infarction (MI) initiates adaptive tissue remodeling, which is e ssential for heart function (such as infarct healing) but is also important for maladaptive remodeling (for example, reactive fibrosis and left ventri cular dilation). The effect of aldosterone receptor antagonism on these pro cesses was evaluated in Sprague-Dawley rats using eplerenone, a selective a ldosterone receptor antagonist. Infarct healing and left ventricular remode ling were evaluated at 3, 7, and 28 days after MI by determination of the d iastolic pressure-volume relationship of the left ventricle, the infarct-th inning ratio, and the collagen-volume fraction. Eplerenone did not affect r eparative collagen deposition as was evidenced by a similar collagen volume fraction in the infarcted myocardium between eplerenone and vehicle-treate d groups at 7 and 28 days post-MI. In addition, the thinning ratio, which i s an index of infarct expansion, was comparable between the eplerenone and vehicle-treated animals at 7 and 28 days post-MI. A protective effect of ep lerenone was demonstrated at 28 days post-MI, where reactive fibrosis in th e viable myocardium was reduced in eplerenone-treated animals compared with vehicle-treated animals. Thus aldosterone receptor antagonism does not ret ard infarct healing but rather protects against maladaptive responses after MI.