Sleep apnea, coronary artery calcium density, and cardiovascular events: results from the Multi-Ethnic Study of Atherosclerosis

Study Objectives: Evaluate the association between obstructive sleep apnea (OSA), coronary artery calcium (CAC) density, and cardiovascular events in the MultiEthnic Study of Atherosclerosis (MESA). Methods: We analyzed 1,041 participants with nonzero CAC scores who had polysomnography and CAC density data from the fifth examination of the Multi-Ethnic Study of Atherosclerosis. OSA was defined as apnea-hypopnea index >= 15 events/h. Multivariable linear regression models were used to evaluate the independent association between OSA and CAC density. Additionally, we evaluated the impact of OSA on associations of CAC measures with incident cardiovascular disease events by testing for interaction in Cox proportional hazard regression models. Results: Our analytical sample was 45% female with a mean age of 70.6+/- 9 years. Of this sample, 36.7% (n = 383/1041) had OSA (apnea-hypopnea index >= 15 events/h). OSA was inversely and weakly associated with CAC density (beta = - 0.09; 95% CI, - 0.17 to -0.02; P = .014) and remained significantly associated after controlling for traditional cardiovascular risk factors (beta = -0.08; 95% CI,-0.16 to 0; P= .043). However, this inverse association was attenuated after controlling for body mass index (beta = -0.05; 95% CI,-0.13 to 0.02; P= .174). The mean follow-up period for cardiovascular disease events was 13.3 +/- 2.8 years. Additionally, exploratory analysis demonstrated that CAC density was independently and inversely associated with cardiovascular disease events only in the non-OSA subgroup (apneahypopnea index <= 15 events/h) (hazard ratio, 0.509; 95% CI, 0.323-0.801); P = .0035). Conclusions: OSA was associated with lower CAC density, but this association was attenuated by body mass index. Further, increased CAC density was associated with a reduced risk of cardiovascular disease events only in individuals within the non-OSA group in exploratory analysis.