Effects of obstructive sleep apnea on inflammatory markers in patients with acute coronary syndrome

Objective To examine the prevalence of obstructive sleep apnea (OSA) in patients with acute coronary syndrome (ACS), and to evaluate the relationship of OSA with inflammatory biomarkers in ACS patients. Methods Patients with ACS treated at Beijing Anzhen Hopital from June 2015 to May 2017 were enrolled. Subjects were evaluated for OSA by sleep study, and were divided into a normal-mild OSA group (Apnea Hypopnea Index, AHI < 15 times/h) and a moderate-severe OSA group (AHI≥15 times/h). Laboratory examination and sleep study were monitored to analyze the effects of OSA on biomarkers by LSD-t test, Mann-whitney U test, or Chi-square test. Correlation analysis was performed to analyze the association of OSA with high sensitivity C-reactive protein (hs-CRP) by Spearman correlation anaylsis. Results A cohort of 836 patients with ACS were enrolled including 408 patients in the normal-mild OSA group and 428 patients in the moderate-severe OSA group. The levels of leukocyte(×109L) [7.78 (6.33, 9.86) vs 7.29 (6.01, 9.16), P=0.006], neutrophils(×109L) [5.05 (3.84, 7.23) vs 4.80 (3.74, 6.66), P=0.044], monocytes(×109L) [0.42 (0.33, 0.54) vs 0.39 (0.31, 0.51), P=0.033], hs-CRP(mg/L) [3.18 (1.10, 11.52) vs 1.78 (0.65, 6.46), P<0.01], fibrinogen(g/L) [3.17 (2.87, 3.74) vs 2.97 (2.59, 3.50), P=0.002], and uric acid(μmol/L) [360 (302, 422) vs 341(283, 407), P=0.006] in the moderate-severe OSA group were significant higher than those in the normal-mild OSA group. AHI (correlation coefficient=0.171, R2=0.020, P<0.01), ODI (correlation coefficient = 0.201, R2=0.027, P<0.01), and TSaO2 < 90% (correlation coefficient = 0.105, R2=0.005, P<0.01) were positively correlated with hs-CRP; minimal SaO2 (correlation coefficient=-0.100, R2=0.001, P=0.008) and mean SaO2 (correlation coefficient = -0.127, R2= 0.006, P<0.01) were negatively correlated with hs-CRP. Conclusions For patients with ACS, the level of inflammatory markers in the moderate-severe OSA group is significantly higher than that in the normal-mild OSA group. Hs-CRP is significantly associated with the severity of OSA. Diagnosis and monitoring of OSA should be considered in ACS management in the future. Key words: Acute coronary syndrome; Obstructive sleep apnea; Inflammatory marker; C-reactive protein