Sleep apnea is a stronger predictor for coronary heart disease than traditional risk factors

Sleep apnea (SA) may be linked to coronary artery disease (CAD). Both conditions have similar risk factors, confounding the analyses. Investigation of the lipid profile is routine in the adult population, even without symptoms or suspected cardiac ailment. SA, however, remains underdiagnosed even in the presence of unambiguous clinical manifestations.

The aim of this study was to verify the association between SA and CAD, adjusting for usual CAD risk factors.

Patients who underwent diagnostic or therapeutic coronariography and portable type III polysomnography were studied. The severity of SA was determined by the apnea-hypopnea index (AHI). We measured classic CAD risk factors: fasting glucose; total, HDL, and LDL cholesterols; triglycerides; uric acid, and high-sensitivity C-reactive protein. We excluded patients older than 65 years, with body mass index higher than 40 kg/m(2), with diabetes, and with history of smoking in the last year.

Of 55 included patients, 28 had AHI > 14, showing an odds ratio of 8.7 for CAD. Patients without (n = 29) and with CAD (n = 26), showed AHI of, respectively, 11 ± 11 and 23 ± 14 per hour (P = 0.001). In a binary logistic regression to predict CAD, controlling for all the above risk factors, the only variables entered in the stepwise model were AHI (either as continuous or categorical variable) and uric acid.

In a sample without smokers, morbidly obese, or diabetic patients, AHI is the main predictor of CAD. SA should integrate the set of risk factors routinely assessed in clinical investigation for coronary disease risk stratification.