Effect of mitral valve surgery in patients with dilated cardiomyopathy and severe functional mitral regurgitation

Background: Surgical treatment of functional mitral regurgitation (FMR) improves ventricular remodeling in patients with dilated cardiomyopathy (DCM). However, it is unclear whether surgical treatment improves long-term outcomes. We investigated the effects of mitral valve (MV) surgery in patients with DCM and FMR. Methods and Results: Of 525 patients with DCM hospitalized due to heart failure between January 1996 and September 2014, 70 who had severe FMR despite receiving optimal medical therapy were enrolled in the study. Of these patients, 16 underwent surgery for FMR (surgery group; repair=14, replacement=2); the remaining 54 who refused or decided not to undergo surgery were classified as the medication group. There were no differences in age, sex, medication, or echocardiographic parameters between the 2 groups (P>0.05). During the mean follow-up period of 53.6±43.6 months, the occurrence of clinical outcomes (i.e., all-cause death or left ventricular assist device implantation) was 54.3%; the occurrence of clinical outcomes was lower in the surgery group (P=0.008, log-rank test). Multivariate Cox regression analysis using clinical data revealed that MV surgery (hazard ratio [HR] 0.257, 95% confidence interval [CI] 0.103–0.640; P=0.004) and diabetes mellitus (HR 2.924, 95% CI 1.243–6.876; P=0.014) were independent predictors of clinical outcomes after adjusting for age and sex. Conclusions: Surgery for severe FMR provides better long-term outcomes in patients with DCM.