All the subjects will benefit from a clinical, anthropometric and biological evaluation. In addition, conventional echocardiography (remodelling and global diastolic and systolic functions) complemented by a functional analysis by tissue Doppler imaging will be performed. Furthermore, 2D cine loops will be recorded in the apical 4, 3 and 2- chamber views for the objective assessment of myocardial longitudinal deformations as well as in the parasternal short axis (base and apex) for the evaluation of the circumferential deformations and basal and apical rotations and left ventricular torsion, at rest and under low dose of dobutamine (110 and 120 bpm).