Ventricular enlargement and reduced survival after myocardial infarction

Abstract

Increased ventricular volume is one of the most powerful predictors of reduced survival in patients with heart disease. Despite its well-documented prognostic significance, the magnitude of the progression of ventricular dilatation from the acute to the chronic phase of myocardial infarction has only recently been appreciated. In an experimental preparation of myocardial infarction in rats, left ventricular cavitary volume increased progressively even after histologic resolution of the infarct region. We hypothesized that this remodeling of the infarcted left ventricle was a response to an increase in both systolic and diastolic wall stresses and that captopril, by reducing wall stress, would attenuate the process. For comparably sized infarcts, the captopril-treated rats had smaller ventricular volumes at common distending pressures, yet they had maintained or improved cardiac output. Most importantly, long-term captopril therapy also prolonged the survival of these rats with experimental myocardial infarction. The implication of these animal studies is that the potential exists for the attenuation of progressive ventricular enlargement and improvement of survival of patients recovering from a myocardial infarction. At the present time, no information is available in patients as to the therapeutic potential of interrupting this insidious process of ventricular dilatation in order to improve survival. Clinical trials are required to determine whether salutary benefits similar to those observed in animals can be provided to patients recovering from a myocardial infarction.