October 24, 2008

Even Mild Sleep Apnea Hikes Heart Risk

FRIDAY, Oct. 24 (HealthDay News) -- Even mild sleep apnea may boost the risk of cardiovascular disease by harming endothelial function and increasing arterial stiffness, a new British study says.

"It was previously known that people with OSA [obstructive sleep apnea] severe enough to affect their daytime alertness and manifest in other ways are at increased risk of cardiovascular disease, but this finding suggests that many more people, some of whom may be completely unaware that they even have OSA, are at risk than previously thought," study author Dr. Malcolm Kohler, of the Oxford Centre for Respiratory Medicine, said in an American Thoracic Society news release.

Kohler and his colleagues assessed differences in endothelial function, arterial stiffness and blood pressure in 64 patients with mild sleep apnea and 64 people without the condition.

"In our study, the augmentation index, a measure of central arterial stiffness that independently predicts cardiovascular events in high-risk populations, was significantly higher in patients with minimally symptomatic OSA compared to matched controls," Kohler said. "We also found impaired endothelial function as indicated by decreased vascular reactivity of their arteries compared to control subjects without OSA."

He noted that the difference in arterial stiffness between participants with mild sleep apnea and those without sleep apnea was "comparable in size to the effect seen after four weeks continuous positive airway pressure (CPAP) therapy in patients with moderate to severe symptomatic OSA."

This suggests that CPAP may provide a cardiovascular benefit to patients with mild sleep apnea, Kohler said.

The study was published in the November issue of the American Journal of Respiratory and Critical Care Medicine.

More information

The American Academy of Family Physicians has more about sleep apnea.

-- Robert Preidt
SOURCE: American Thoracic Society, news release, Oct. 24, 2008
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