BALTIMORE – Individuals with moderate to severe and thus may be at a heightened risk of cardiovascular events, according to an analysis of a national, multisite research study presented at the annual meeting of the Associated Professional Sleep Societies.
Dr. Younghoon Kwon
The study evaluated a subgroup of 708 patients with no history of cardiovascular disease (CVD) from the Multi-Ethnic Study of Atherosclerosis (MESA).
Dr. Kwon noted that previous studies have shown that patients with thoracic aortopathy have a high rate of obstructive sleep apnea (OSA) (Am J Respir Crit Care Med. 2003;168:1528-31), and those with OSA tend to have higher thoracic aortic size (J Am Coll Cardiol. 2008;52:885-6). “There’s also a degree of evidence suggesting that OSA is associated with high arterial stiffness, which is a marker of primary organ damage and a major cardiovascular risk that is predictive of cardiovascular disease,” Dr. Kwon said (J Intl Med Res. 2011;39:228-38). However, he also noted that some studies have found no relationship between OSA and aortic disease (Respiration. 2006;73:741-50). “The question can be raised as to whether sleep apnea may have implications” in thoracic aortic disease, he said.
Dr. Kwon’s study evaluated three groups: patients with no OSA (apnea hypopnea index [AHI] less than 5, n = 87); mild OSA (AHI 5-15, n = 215); and severe OSA (AHI greater than 15, n = 406). All patients had polysomnography as part of an ancillary study. Cardiac MRI measured these three features of aortic function and physiology (unadjusted results):
Diameter at the pulmonary artery bifurcation, which ranged from 3.13 cm in patients with no OSA to 3.37 cm in those with severe OSA (P = .0017).
Pulse wave velocity, which averaged 8.07 m/s in the no-OSA group and 9.11 m/s in the severe group (P less than .0001).
Distensibility, or aortic stiffness, which was 1.73%/mm Hg in the no-OSA group, 1.54%/mm Hg in the mild group and 1.68%/mm Hg in the severe group (P = .0141).
“There was maybe some higher pulse wave velocity across the significant OSA group,” Dr. Kwon said. “However, with aortic distensibility, there did not seem to be any significant trend.”
In the adjusted analysis of aortic diameter, “there did appear to be a small but significant difference in the significant OSA group, compared with the reference group,” Dr. Kwon said. He also noted that women with OSA typically had significantly larger aortic diameters than did non-OSA counterparts, whereas that trend was not as pronounced in men.
“Thoracic aorta size does seem to increase with OSA severity, but this has a sex-interaction component; it’s more pronounced in women,” Dr. Kwon said. He also noted a discrepancy in the results: “The functional properties of the aorta did not seem to bear a significant association with OSA severity.”