Sleep Apnea Increases Stroke Risk

An observational study of more than 1,000 patients has found that sleep apnea significantly increases the risk of stroke or death from any cause, and the risk is linked to the severity of sleep apnea. The increased risk was independent of other factors, such as hypertension.

A second study on sleep apnea revealed that positive airway pressure (CPAP), which improved cardiovascular and sleep function in patients with both heart failure and sleep apnea, failed to improve survival. The results of both studies were published in the November 10, 2005, issue of The New England Journal of Medicine.

In the first study, all sleep apnea patients underwent polysomnography, while the researchers noted the incidence of strokes and death. Obstructive sleep apnea (OSA) was defined as five or more episodes of OSA. The participants were over 50 without a history of heart attack or stroke at the beginning of the study. They were followed for almost 3.5 years. The results showed that OSA patients had a risk of stroke or death from any cause that was more than twice that of controls. The author of the study was Virend K. Somers, M.D., Ph.D., of the Mayo Clinic (Rochester, MN, USA).

In the second study, T. Douglas Bradley, M.D., of the department of medicine at the University of Toronto (Canada), assigned 258 heart-failure patients with sleep apnea to a group receiving CPAP or no CPAP. They followed the patients for an average of two years, until heart transplantation or death occurred or the study ended, with assessments at regular intervals. However, while the CPAP group appeared to do better on some measures of function, the CPAP made no difference in terms of the study's main endpoints.

"The cardiovascular implications of normal and disturbed sleep, and of sleep apnea in particular, have only recently gained prominence,” said Dr. Somers, in an accompanying editorial. "Perhaps CPAP is simply not a viable therapeutic option for death-rate reduction in patients with heart failure.”





Related Links:
Mayo Clinic
U. of Toronto