Dutch-AMR: Early Mitral Valve Repair Versus Watchful Waiting in Asymptomatic Patients With Severe Mitral Regurgitation

Inclusion Criteria: * 18-75 years. * Asymptomatic patients. "Asymptomatic" is defined as absence of subjective limitations of exercise capacity or complaints expressed by the patient and confirmed by the treating cardiologist. * Severe organic mitral valve regurgitation. "Severe organic mitral valve regurgitation" is defined as non-ischemic mitral valve regurgitation with an organic cause (intrinsic valve lesion) as determined by echocardiographic core-lab reading based on the criteria for definition of severe MR as issued by the ESC guidelines \[4\]. For practical reasons, referring cardiologists can use an ESC guidelines based index that was validated in the investigator's core-lab (Jansen et al, Practical echocardiographic semi-quantitative scoring system to determine severity of mitral regurgitation. Abstract presentation at ESC EUROECHO Congress 2011 and annual spring congress 2012 Netherlands Society of Cardiology). * Preserved left ventricular function, "Preserved left ventricular function" is defined as left ventricular ejection fraction \>60% and left ventricular end-systolic dimension \<45 mm (no indexed value, measured by echocardiography). * The likelihood of MV repair should be more than 90% determined by the local heart team with a cardiologist and cardiothoracic surgeon. Exclusion Criteria: * Pulmonary hypertension (\>50 mmHg at rest). * Atrial fibrillation, either on 12-lead ECG or holter-monitoring. * Physical inability as determined by the heart team to undergo surgery. * Other life-threatening morbidity. * Higher expected surgical risks in advance, according to the dedicated heart team. * Patients with moderate to severe kidney disease (estimated glomerular filtration rate (eGFR) less than 30 mL/min). * Flail leaflet together with a left ventricular end systolic diameter (LVESD) ≥40 mm (no indexed value)