Effectiveness and Safety of Mitral Valve Repair With the NeoChord DS1000 Artificial Chordae Delivery System Versus Conventional Surgery in Patients With Severe Primary Mitral Regurgitation Due to Isolated Leaflet Prolapse

Inclusion Criteria: * Severe primary mitral regurgitation (grade 3+ or 4+) * Class I indication for MV Surgery according to ESC/EACTS and AHA/ACC guidelines: 1. Symptomatic patients and/or 2. LV (Left Ventricular) dysfunction : LVESD ≥45 mm and/or 30≤ LVEF ≤60% * Leaflet prolapse of P2 and/or A2 * Predicted coaptation length \> 4 mm * Candidates for surgical mitral valve repair according to heart team * Patient able to sign an informed consent form * Patient benefiting from a social insurance system or a similar system Exclusion Criteria: * Asymptomatic patients with preserved LV function * Complex mechanism of MR (leaflet perforation, severe calcifications, commissural extension, etc) * Secondary MR * Predicted post-repair coaptation length less than 4 mm * Atrial fibrillation * Inflammatory or infective valve disease * Severe LV dilation (DTD \> 65 mm) * Significant mitral annulus dilatation (D \> 45 mm) * Surgical indication of tricuspid annulus * Contraindication to TEE (transesophageal echocardiographic ) or inadequate image quality * Need for any other concomitant cardiac procedure * Concurrent medical condition with a life expectancy of less than 24 months * Patient unable to understand the purpose of the trial * Patient \< 18 years old * Participation to another trial that would interfere with this trial * Pregnancy