Serum heparanase levels are associated with endothelial dysfunction in patients with obstructive sleep apnea

Background and aim Obstructive sleep apnea syndrome (OSAS) is well‐known to be associated with high risk for cardiovascular (CV) diseases. Heparanase has been recently shown to be related to increased inflammation and vulnerability of the atherosclerotic plaques. Herein we aimed to investigate the relationships between OSAS, heparanase and endothelial dysfunction. Materials and methods A total of 120 patients with varying severity of OSAS and 31 controls without OSAS were enrolled. Flow‐mediated dilatation (FMD) was measured as an indicator of endothelial dysfunction. Serum heparanase levels were measured with ELISA. Results Serum heparanase levels increased in a stepwise fashion from controls to patients with more severe OSAS. When FMD was compared with controls and various degrees of severity of OSAS, a stepwise decrease in FMD was observed. Serum heparanase levels were found to be significantly associated with apnea hypopnea index (AHI) ( r  = .57, P  < .001) and FMD ( r = –.37, P  < .001) in patients with OSAS. Serum heparanase levels were significantly associated with hemoglobin‐A1c and body mass index in patients with OSAS. Serum heparanase and uric acid levels were independent predictors of FMD in linear regression analysis ( R 2  = .506, P  < .001; P  < .001 and P  = .001 respectively). Conclusions Serum heparanase levels were significantly increased in patients with OSAS and associated with the severity of OSAS (AHI) and endothelial dysfunction (FMD). Increased heparanase activity in OSAS may be related to increased cardiovascular risk in patients with OSAS.