Objective Obstructive sleep apnea (OSA) is an independent risk factor for cardiovascular morbidity and mortality. The mechanism is unknown, but recent studies provide evidence that endothelial dysfunction might contribute. So we investigate the relationship between obstructive sleep apnea and endothelin-1 (ET-1) plasma levels in patients with coronary heart disease.
Methods 287 patients with coronary heart disease were enrolled and an overnight polysomnography was performed to all of them. According to the apnea-hypopnoea index, the patients were divided into four groups: no OSA group (AHI<5, n=58), mild OSA group (5≤AHI<15, n=82), moderate OSA group (15≤AHI<30, n=70), severe OSA group (AHI≥30, n=77). Plasma levels of endothelin-1 were detected to all the patients.
Results Compared with no and mild OSA group, endothelin-1 plasma levels in severe OSA group elevated significantly (p=0.009), even after analysis in a general linear model with correction for confounders. Plasma ET-1 levels showed an increasing trend within no OSA, mild OSA and moderate OSA group, however no statistically significant was observed between no OSA group and patients with mild or moderate OSA, respectively (p=0.421, p=0.226).
Conclusion Among patients with coronary heart disease, plasma ET-1 levels elevated significantly in severe OSA group. This might support that severe OSA has more effects on endothelium function for coronary heart disease than mild and moderate OSA.