People with obstructive sleep apnea (OSA) have more non-calcified plaque in their coronary arteries, according to a study presented at the 2010 annual meeting of the Radiological Society of North America (RSNA).

"Our study reveals that individuals with obstructive sleep apnea are prone to developing an aggressive form of atherosclerosis that puts them at risk for impaired blood flow and cardiovascular events," said U. Joseph Schoepf, M.D., professor of radiology and medicine and director of cardiovascular imaging at the Medical University of South Carolina in Charleston, S.C.

In the study, 49 obese patients, mean age 61, with OSA and a mean body mass index (BMI) of 33, and 46 obese patients without the disorder (mean age of 60 and mean BMI of 30) underwent coronary CT angiography (cCTA), which provides detailed pictures and information on plaque buildup and narrowing in the vessels. The OSA group included 26 men and 23 women, and the matched control group included 22 men and 24 women.

The imaging revealed that the amount of calcified plaque in the coronary arteries was not significantly different between the two groups, but the overall composition of vessel plaque was notably different.

"Compared to the non-OSA group, the patients with OSA had a significantly higher prevalence of non-calcified and mixed plaque," Dr. Schoepf said.

Non-calcified plaque is more vulnerable to rupturing and causing a blood clot, which could lead to a myocardial infarction or other cardiovascular event.

Patients with OSA also had a significantly higher prevalence of vessel narrowing and more extensive vessel involvement. Eighty-eight percent of OSA patients had narrowing in at least one vessel, compared to 59 percent of non-OSA patients. One-third of OSA patients had narrowing in four vessels.

"Coronary CT angiography is an effective way to noninvasively diagnose non-calcified and mixed plaque," Dr. Schoepf said. "With technological advancements that are lowering the radiation dose required for cCTA, this exam could become a screening tool for obese individuals at increased risk for cardiovascular disease."

Coauthors are Garrett Rowe, B.S., Andrew Armstrong, B.Sc., Joseph Abro, M.A., Adrian Parker, B.A., and Sunil Sharma, M.D.