Functional mitral regurgitation and left ventricular systolic dysfunction in the recent era of cardiovascular clinical practice, an observational cohort study.

Functional mitral regurgitation (MR) is frequently associated with left ventricular systolic dysfunction (LVSD). Ventricular volume overload that occurs in patients with MR may lead to a progression of myocardial dysfunction. However, the prevalence and clinical outcomes of functional MR in Japanese patients with LVSD remain unclear. The aim of the present study is to clarify the prevalence and prognosis of functional MR in Japanese LVSD patients in the contemporary era. We followed patients with LVSD (LV ejection fraction (LVEF) ⩽ 40%) who were listed within a single, hospital-based cohort in the Shinken Database from 2004 to 2011, which was composed of all new patients (n = 17,517) who visited the Cardiovascular Institute. A total of 506 patients were included: 86 FMR (moderate-to-severe functional MR) patients and 420 non-FMR (none or mild functional MR) patients. FMR patients were older, had lower rates of hypertension and ischemic heart disease but had higher rates of chronic kidney disease, dilated cardiomyopathy and New York Heart Association III/IV classification. FMR patients had higher brain natriuretic peptide levels and lower LVEF. The Kaplan-Meier curves revealed that the incidence of all-cause death, cardiovascular death and heart failure (HF) admission was significantly higher in FMR patients. The presence of FMR was independently associated with a significantly higher risk of composite end point, including all-cause death and/or HF admission (hazard ratio 1.551, 95% confidence interval 1.045-2.303, P = 0.029). FMR was common in Japanese patients with LVSD and was associated with adverse long-term outcomes. Future study is warranted to establish the optimal therapeutic strategy for FMR and LVSD.