Degenerative mitral regurgitation (MR) due to leaflet prolapse is frequent and can be surgically repaired in the vast majority of patients. Despite the efficacy of mitral valve repair, an ongoing international controversy exists regarding the need to perform early surgery in asymptomatic patients with severe MR and no sign of LV dysfunction in whom the probability of successful and durable repair is very high. In this group of patients, differing views of the risks of uncorrected severe MR exist: considered as benign by those supporting medical watchful waiting or associated with significant excess mortality/morbidity by those advocating early surgery. This controversy can only be resolved by a randomized controlled trial which is still lacking. The main objective is to demonstrate the superiority of early mitral valve repair in patients with asymptomatic severe MR due to leaflet prolapse compared to an initial conservative management in terms of all-cause death and cardiovascular morbidity during five years follow-up.