Degenerative mitral insufficiency secondary to valve prolapse is the most common valve disease in Western countries. In the absence of specific treatment, it spontaneously progresses to heart failure and death when it is severe. Surgical mitral valve repair (or mitral plastic surgery) is the preferred treatment for primary mitral insufficiency by prolapse in case of severe leakage if associated with clinical and/or echocardiographic markers of poor prognosis (i.e., with high risk of morbi-mortality during their follow-up). It is therefore essential to refine the risk stratification of these patients in order to identify at-risk patients who should potentially benefit earlier from invasive care (cardiac surgery), or conversely, close monitoring. A number of echocardiographic and MRI parameters may have been associated with a poorer prognosis. A cohort of patients with primary mitral insufficiency (MI) will be followed to study the relationships of a set of factors to patient prognosis.