Should patients with asymptomatic severe mitral regurgitation with good left ventricular function undergo surgical repair?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was, 'Does severe asymptomatic mitral regurgitation (MR) require surgery or is watch and wait the optimal strategy?'. Over 103 papers were found using the reported search, and 10 represented the best evidence to answer this clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. No studies in the modern era have shown significant survival benefit for patients undergoing surgery for asymptomatic severe MR if they have good left ventricular (LV) function. The progression rate to surgery on developing symptoms is 10% per year in these patients. Ling et al. reported a 63% incidence of congestive heart failure and 30% incidence of chronic atrial fibrillation (AF) at 10 years for conservative treatment, during which period 90% either underwent surgery or died. In addition, one study of 478 patients with good LV operated on in the 1980s showed a 76% 10-year survival in patients who were NYHA I/II but only a 48% 10-year survival in patients with NYHA III/IV although this group was older and had more AF. Early surgery has very good peri- and postoperative survival rates, and the American Heart Association currently recommend that these patients may be operated on if the chance of repair is >90%. Patients may, therefore, be reassured that either strategy is acceptable.