Abstract: Objective: To evaluate the early cardiac injury caused by obstructive sleep apnea (OSA) before the development of cardiovascular symptoms of OSA. Methods: Ninety-two patients without any known cardiovascular disorders who underwent polysomnography (PSG) were enrolled in the study. Subjects were divided into mild, moderate, and severe OSA groups by their apnea hypopnea index (AHI), and 25 healthy individuals were identified as controls. After PSG examination, fasting blood samples for the evaluation of N-terminal pro-brain natriuretic peptide (NT-proBNP) and heart-type fatty acid binding protein (h-FABP) were collected in the morning, and left ventricular(LV) functions were assessed by using echocardiographic methods. Thirty moderate and severe OSA patients were treated with continuous positive airway pressure respectively (CPAP).Results: The levels of h-FABP and NT-proBNP were obviously higher in all OSA groups than those in the control group (P<0.01), and were positively correlated with AHI (P<0.01). The Em/Am values of all OSA groups and E/A values of the moderate and severe OSA groups were significantly reduced (P<0.01). The difference in Em/Am values among the groups was statistically significant (P<0.01). Compared with those before treatment, h-FABP and NT-BNP levels in serum of OSA patients after CPAP treatment were significantly reduced (P<0.01), and Em/Am and E/A values were significantly increased (P<0.01). Conclusion: Left ventricular diastolic dysfunction and early myocardial microtrauma are major manifestations of early heart damage in patients with OSA. CPAP therapy could significantly improve early cardiac damage in OSA patients.

Key words: obstructive sleep apnea, early cardiac injury, serum markers, echocardiography, cardiac function change, continuous positive airway pressure