Athlete's Heart or Arrhythmogenic Right Ventricular Cardiomyopathy: Contribution of Exercise Cardiovascular Magnetic Resonance (CMR)

Comparison of the RV contractile reserve in 4 groups of patients: Arrhythmogenic right ventricular cardiomyopathy (ARVC) patients; endurance athletes with a dilated RV, endurance athletes with normal RV, untrained subject with normal RV. Patients will come to the hospital for 3 visits (3 half days): * Visit 1: clinical evaluation, rest ECG, rest echocardiography, cardio-pulmonary exercise test. * Visit 2: exercise echocardiography, holter ECG monitor (48 yours) * Visit 3: rest CMR and exercise CMR (ergocycle)