Abstract 1651: Is Obstructive Sleep Apnea Associated With Endothelial Dysfunction? The Akershus Sleep Apnea Project
Introduction: Severe obstructive sleep apnea (OSA) has been associated with increased risk of cardiovascular events. Whether OSA of mild to moderate severity in subjects drawn from the general population is associated with endothelial dysfunction, a precursor of atherosclerosis, is unknown.
Hypothesis: We wanted to assess the hypothesis that there is an association between endothelial dysfunction, as measured by peripheral arterial tonometry, and the apnea-hyponea index (AHI) in a large population-based sample of subjects.
Methods: From a Norwegian, population-based cohort of 30 000 subjects aged 30 – 65 years we invited 518 subjects to attended, in-hospital polysomnography. Oversampling of subjects classified as being at high risk of OSA was performed. Endothelial function studies were performed the following morning on 484 subjects (mean age 48 years, 57 % male). Endothelial function was assessed by measuring the digital pulse wave amplitude reactive hyperemic response, expressed as the reactive hyperemia index (RHI), using the EndoPAT 2000 (Itamar Medical, Caesarea, Israel).
Results: Out of the 484 subjects, 349 subjects were classified as being at high risk of OSA, whereas 135 subjects were classified as low risk. Subjects were categorized according to AHI cutoffs that correspond to mild, moderate and severe degrees of OSA. The RHI was significantly lower in subjects with AHI >30 than those with AHI<5 (Table⇓). In a multivariable linear regression model, adjusting for conventional cardiovascular risk factors, the association between AHI and RHI was attenuated and no longer significant.
Conclusions: Severe, but not mild to moderate OSA, is associated with an impaired digital pulse wave amplitude reactive hyperemic response in a population-based cohort. However, this association can be explained by a clustering of traditional cardiovascular risk factors in subjects with severe OSA.