Background: The efficacy of ACE inhibitors in congestive heart failure (CHF) might be affected by the pathophysiological status present at the onset of treatment. We compared in a rat model the effects of ACE inhibition (lisinopril, 10 mg.kg-1.d-1) initiated early (1 week) or late (3 months) after myocardial infarction (i.e., at time points corresponding to moderate or severe CHF without or with established cardiac remodeling).
Methods and results: Survival was improved by early treatment at 3 months (from 76% to 95%) and by both early and delayed treatment at 9 months (placebo, 28%; early, 90%; delayed, 61%). Delayed treatment was initiated in a more severe pathophysiological context of CHF than early treatment, illustrated in untreated rats by higher left ventricular (LV) end-diastolic and central venous pressures and by increased LV weight and LV cavity circumference. After 9 months, early and delayed treatments reduced systolic, LV end-diastolic, and central venous pressures. Both treatments also similarly decreased LV weight, LV cavity circumference, and LV collagen density.
Conclusions: In this rat model of CHF, early and delayed ACE inhibitor treatments both increase survival and exert similar beneficial effects on cardiac hemodynamics and remodeling. Although early treatment prevents the development of ventricular dysfunction and remodeling, delayed treatment is capable of reversing cardiac hypertrophy and remodeling, as well as ventricular dysfunction. Thus, ACE inhibitors exert marked beneficial effects even when treatment is initiated late into the evolution of heart failure (ie, at a time of established ventricular dysfunction and remodeling).