Relationship between obstructive sleep apnea and coronary microcirculatory function among patients with cardiac syndrome X.

OBJECTIVES

Obstructive sleep apnea (OSA) is an emerging risk factor for cardiovascular disease. Microcirculatory dysfunction has been proposed as a potential mechanism in the pathogenesis of cardiovascular disease in OSA. This study aims to investigate the relationship between OSA and coronary microcirculatory function.

PATIENTS AND

METHODS

One thousand and thirty-eight patients (598 female, mean age 60±9 years) with angiographically normal coronary arteries were divided into three groups with non-OSA of apnea-hypopnea index (AHI) less than 5 (n=403), mild-to-moderate OSA of AHI 5-30 (n=386), and severe OSA of AHI more than 30 (n=249).

RESULTS

The prevalence of OSA was very high in patients with syndrome X (635/1038). Patients with higher AHI values had a lower coronary flow reserve, were more likely to have a higher total cholesterol, low-density lipoprotein cholesterol, and high sensitive C-reactive protein, and were more likely to be obese. Compared with the non-OSA group, the multivariable-adjusted odds ratio of coronary microcirculatory function for an AHI of 5-30 events/h was 1.93, 95% confidence interval 1.66-3.47, P=0.038, and for an AHI of more than 30 events/h was 2.18, 95% confidence interval 1.62-4.23, P=0.024, in model 1; and coronary microcirculatory function for an AHI of 5-30 events/h and more than 30 events/h odds ratio 1.31, 95% confidence interval 1.06-2.88, P=0.043, versus odds ratio 2.08, 95% confidence interval 1.03-2.16, P=0.036, in model 2.

CONCLUSION

As compared with having no sleep apnea, categories with higher AHI were associated with increased odds of lower coronary flow reserve. The data suggested a close relationship between OSA and coronary microcirculatory function in atherosclerosis.