All patients underwent complete transthoracic echocardiographic study with Vivid S6 (GE Medical System, Tirat Carmel, Israel) with a 1,5 - 3,6 megahertz cardiac sector probe. A standard M-mode, two-dimensional and Doppler echocardiographic examination was performed according to the guidelines of American Society of Echocardiography. Three consecutive cycles were averaged for every parameter. The same experienced cardiologist who was blinded to the presence or absence of OSA performed all echocardiographic examinations. Left ventricular end-diastolic diameter (LVED), thickness of intraventricular septum at end diastole (IVS), left ventricular posterior wall at end diastole (LVPW) and left ventricular mass (LVM) were measured according to American Society of Echocardiography recommendations. The LVH was defined as the IVS or the LVPW>12 mm. The left ventricular mass was calculated using a simple and anatomically validated formula: