Heart Groups Acknowledge Apnea
In the face of rising rates of obesity, hypertension, atrial fibrillation, and heart failure, physicians need to be mindful of the mounting evidence for a link between sleep apnea and cardiovascular disease when evaluating patients, according to a joint American Heart Association and American College of Cardiology Foundation scientific statement.
“We feel it is important to alert the cardiovascular community to the implications of this emerging area of research. It is possible that diagnosing and treating sleep apnea may prove to be an important opportunity to advance our efforts at preventing and treating heart disease,” Dr. Virend K. Somers said in a press statement. Dr. Somers chaired the joint statement writing committee.
Dr. Somers has received research support from Respironics and the ResMed Foundation; he is also a consultant to Respironics. Both companies make devices to treat sleep apnea. In addition, Dr. David P. White, committee cochair, is the chief medical officer for Respironics.
Sleep-related breathing disorders are very common among patients with established cardiovascular disease. Obstructive sleep apnea (OSA) affects a large proportion of patients with hypertension, coronary artery disease, stroke, and atrial fibrillation. Central sleep apnea (CSA), in contrast, occurs mainly in patients with heart failure.
Cardiologists are seeing more patients with sleep apnea diagnoses, according to Dr. Rita Redberg, director of women's cardiovascular services at the University of California, San Francisco. “I have noticed an increase in the number of patients who tell me that they have a diagnosis of sleep apnea,” she said.
While the statement serves as something of a primer on the types of sleep apnea and its relevance to individuals who are at risk for, or who already have, cardiovascular disease, the authors acknowledge that there is much that is not known about the interactions between sleep apnea and cardiovascular disease.
“We need to more clearly define the cause-and-effect relationship between sleep apnea and cardiovascular diseases and risk factors,” Dr. Somers said.
Key questions include whether sleep apnea is a precipitating factor in the development of cardiac and vascular disease, whether sleep apnea accelerates cardiovascular disease progression, and if the treatment of sleep apnea results in clinical improvement, fewer cardiovascular events, and reduced mortality.
However, it will likely be difficult to disentangle the role of sleep apnea in the cardiovascular disease process because obesity is common among patients with sleep apnea, and this association “often obscures differentiation between the effects of obesity, the effects of OSA, and the effects of synergies between these conditions,” the authors wrote. Also, cardiovascular disease is often among several comorbidities of OSA. Hence, it is “unclear whether abnormalities evident in the sleep apnea patient with cardiovascular disease are secondary to the sleep apnea, the cardiovascular condition, or both,” the authors noted.
Given the number of unknowns about the interactions of sleep apnea and cardiovascular disease, and the limited number of randomized control trials, Dr. Redberg noted that she is unlikely to change her practice based on this scientific statement. “It's unclear how this would help my patients,” she said. She already encourages patients to make lifestyle changes aimed at reducing obesity, which is also strongly associated with OSA.
The statement authors noted that there are many challenges to the development of a best practices consensus for sleep apnea and cardiovascular disease. First, sleep medicine education is largely absent from cardiovascular training. In addition, sleep apnea treatment options vary, are predominantly device based, and are not well tolerated by patients. Lastly, it's unclear whether treating sleep apnea confers any real benefit in reducing cardiovascular events.
To complicate matters, there is no clear consensus on how to best quantify severity of sleep apnea, nor is it known what threshold of severity should trigger therapy. It's also not known if thresholds for treatment should be different for people with cardiovascular disease compared with healthy individuals.
PII: S0270-6644(08)70650-7
doi:10.1016/S0270-6644(08)70650-7
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