"Association Between Early Surgical Intervention vs Watchful Waiting and Outcomes for Mitral Regurgitation Due to Flail Mitral Valve Leaflets" 
JAMA Aug 14
http://jama.jamanetwork.com/article.aspx?articleid=1728716   
"Conclusion and Relevance   Among registry patients with mitral valve regurgitation due to flail mitral leaflets, performance of early mitral surgery compared with initial medical management was associated with greater long-term survival and a lower risk of heart failure, with no difference in new-onset atrial fibrillation."