Divergent Left Ventricular Remodeling Pathways in Chronic Primary and Secondary Mitral Regurgitation

Introduction: Left ventricular (LV) dilatation and its transition to decompensatory heart failure (HF) differs in patients with primary and secondary mitral regurgitation (MR). Mapping the temporal changes in LV function, structure and biology in these two MR pathologies, can aid in optimal timing of medical and surgical therapy. Hypothesis: LV dilatation and its transition to HF is more rapid in secondary MR compared to primary MR. Methods: One hundred and one rats were randomized to four groups: (1)MR only; (2)MR with a myocardial infarction(MI); (3) MI only; and (4)sham. Moderate-to-severe MR was introduced by perforating the anterior mitral leaflet with a needle via the LV apex (Fig A1-3) and an MI via left coronary artery ligation (Fig A4). All the rats underwent bi-weekly cardiac echo for 20 weeks. At sacrifice, invasive hemodynamics were measured and pathway specific gene expression was quantified. Results: Moderate-to-severe MR was reproducible and infarct sizes were comparable. EDV was largest in...