Obstructive sleep apnea (OSA) is independently associated with important heart remodeling that further contributes to overt heart failure. Recent evidences using echocardiogram suggested that continuous positive airway pressure (CPAP) has beneficial effects mainly on left ventricle parameters. However, the evidences regarding the right ventricle are scanty. In addition, no previous studies evaluated morphological and functional characteristics in OSA by magnetic resonance imaging (MRI) as well as the impact of CPAP.