Coronary flow reserve is impaired in patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) is common in adult populations. Accumulating data indicate that it is independently associated with a variety of cardiovascular diseases and has prognostic importance in affected cases. In this study, we aimed to evaluate coronary flow reserve (CFR) in patients with OSA and controls.

Sixty-one patients undergoing an overnight polysomnography were enrolled in this study. Patients with an apnea-hypopnea index (AHI) >5 were accepted as OSA group (n = 45) and those with an AHI <5 were taken as controls (n = 16). Using Doppler echocardiography at baseline and following dipyridamole infusion, coronary peak flow velocities were obtained. CFR was calculated as the ratio of peak diastolic flow to baseline diastolic flow. A CFR value <2 was accepted as impaired coronary microvascular function.

The mean age was 50.8 ± 10.8 years, of which 16 (26.2%) were female. Both groups had similar features with regard to demographic and clinical variables. The mean value of CFR was significantly lower in patients with OSA compared to those controls (2.24 ± 0.46 vs. 2.74 ± 0.62, respectively, P = 0.001). An abnormal CFR value was observed in 12 (26.7%) patients with OSA and in 1 (6.3%) participant in control group.

The findings of this study indicate that CFR, an indicator of coronary microvascular function, is significantly impaired in patients with OSA. Coronary microvascular function, an early sign of atherosclerosis, can be evaluated noninvasively in these patients might be used as a predictor of cardiovascular risk.