Do we have to operate on moderate functional mitral regurgitation during aortic valve replacement for aortic stenosis?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Do we have to operate on moderate functional mitral regurgitation (FMR) during aortic valve replacement (AVR) for aortic stenosis (AS)?' Altogether 325 papers were found using the reported search, of which 9 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The current evidence obtained from these papers revealed that the significant predictors of improvement outcome include lower preoperative mitral regurgitation and lower preoperative left ventricle fractional area change. We also know that persistent atrial fibrillation, enlarged left atrium, increased indexed left ventricular mass, pulmonary hypertension and preoperative peak aortic valve gradient < 60 mmHg are predictors of deterioration. Generally, we observed a trend towards improvement or non-progression of FMR following AVR for AS. In the six papers that suggest conservative treatment of FMR, the degree of mitral regurgitation (MR) improved in 45-95%, remained unchanged in 19-38% and deteriorated in 1-14%. In the three papers favoring surgical treatment of MR, the degree of MR improved in 46-69%, stay unchanged in 34-53% and deteriorated in 10%. The current evidence suggests that moderate or less grade of FMR without predictors of deterioration should be treated conservatively and moderate-severe and severe FMR warrants additional surgical procedure. A clearly randomized study, especially in patients with moderate and moderate-severe FMR for AS, seems appropriate to further elucidate surgical strategy.