Surgery for severe mitral regurgitation: The etiology matters

Background: While surgery has been the standard treatment for patients with severe primary mitral regurgitation (PMR), the role of surgery for severe secondary mitral regurgitation (SMR) remained debated. We therefore investigated the prognostic differences of surgery for patients with either severe PMR or SMR. Methods: Subjects hospitalized for heart failure were enrolled from 2002 to 2012. The severity of MR was assessed by continuity equation, and an effective regurgitant orifice area of ≥40 mm²was defined as severe. Long-term survival was then identified by the National Death Registry. Results: A total of 1143 subjects (66.4 ± 16.6 years, 65% men, and 59.7% PMR) with severe MR were analyzed. Compared with PMR, patients with SMR were older, had more comorbidities, greater left atrial and ventricular diameter, and less left ventricular ejection fraction (all p < 0.05). While 47.8% of PMR patients received mitral valve surgery, only 6.9% of SMR patients did. Surgical intervention crudely was associated with 54% reduction of all-cause mortality in PMR (hazard ratio, 0.46; 95% confident interval, 0.32-0.67), and 48% in the subpopulation with SMR (0.52, 0.30-0.91). Propensity score matching analysis demonstrated the survival benefits of mitral valve surgery was observed in patients with PMR (log rank p = 0.024), but not with SMR. Among the unoperated subjects, age, renal function, and right ventricular systolic pressure were common risk factors of mortality, regardless of MR etiology. Conclusion: Mitral valve surgery for patients with heart failure and severe MR was associated with better survival in patients with PMR, but not in those with SMR.