Eplerenone, a selective aldosterone blocker, improves diastolic function in aged rats with small-to-moderate myocardial infarction

Background: The incidence of cardiovascular diseases increases rapidly with age, and the elderly suffer higher morbidity and mortality. Aldosterone blockers have shown benefits in patients with left ventricular (EV) dysfunction and heart failure after myocardial infarction (MI). However, aldosterone blockade efficacy has not been explored in aged animals with MI. Methods and Results: Small-to-moderate MI was induced by coronary artery ligation in 16-month old rats, divided into 3 groups: sham-operated (control, n = 9), MI (n = 9), and MI fed a diet containing eplerenone (120 mg/kg/day, MI+Eplerenone, n = 9) given 18 days postsurgery and up to sacrifice 3 months later. At sacrifice, untreated MI rats did not show overt systolic dysfunction but they had (1) echocardiographic evidences of impaired relaxation (increase of E wave deceleration time and of isovolumic relaxation time, decrease of peak E wave velocity), (2) hemodynamically impaired EV relaxation (EV -dP/dt from 7413 ± 720 to 4956 ± 475 mm Hg/s, P < .05), and (3) significant increase of collagen content in EV interstitium (from 4.27 ± 0.23 to 5.34 ± 0.24%, P < .01) and in aorta (from 19 ± 1 to 24 ± 2%, P < .05). Eplerenone normalized echocardiographic and hemodynamic evidences of diastolic dysfunction, as well as myocardial interstitial collagen and aortic fibrosis (all parameters statistically different from untreated MI). Conclusion: In aged rats with small to moderate MI, eplerenone normalized diastolic relaxation, possibly through a reduction of interstitial fibrosis.