Obstructive sleep apnea syndrome has been linked to cardiovascular complications. The diagnosis of effects of sleep apnea on heart may be difficult before apparent examination findings. The aim of the present study was to evaluate changes of myocardial contractile properties in patients affected by sleep apnea showing tissue Doppler imaging, in the face of quite normal myocardial contractility on standard echocardiography. Shortly, tissue Doppler imaging may represent an early stage of myocardial abnormality despite a preserved global function. (C) 2006 Elsevier Ireland Ltd. All rights reserved.