The primary endpoint is the evolution of the LVEF assessed by contrast echocardiography. The secondary endpoints are: the quality of life SF 36 questionnaire, the NYHA class, the 6-minute-walk test, the QRS duration, the LV end-systolic and diastolic volumes, the NT-pro BNP, MMP 2-9 and TIMP-1 dosages, stimulation and detection ventricular thresholds.