Scientists Look to Link Sleep Apnea and Cardiovascular Disease

By Richard Shank

Researchers at the American Heart Association and the American College of Cardiology just released a joint scientific statement urging more research be done on the relationship between sleep apnea and cardiovascular disease. Sleep-related breathing disorders are highly prevalent in patients with established cardiovascular diseases.

Obstructive sleep apnea (OSA) affects nearly 15 million Americans and is present in a large proportion of patients with hypertension, as well as in those with other cardiovascular disorders, including coronary artery disease, stroke, and atrial fibrillation. Central sleep apnea (CSA) occurs mainly in patients with heart failure.

OSA is characterized by repetitive interruption of ventilation during sleep. This interruption is caused by the collapse of the pharyngeal airway, causing breathing pauses lasting 10 or more seconds. It is thought that more than 85% of patients with clinically significant and treatable OSA have never been diagnosed. OSA is known to increase risk for cardiovascular variations, oxidative stress, insulin resistance, hypertension, and heart failure, among others.

CSA is not as well understood, although it is well known that CSA often coexists with heart failure, stroke, and late-life aging. It is characterized by repetitive and prolonged pauses in breathing resulting from the loss of ventilatory drive. Typically, there is no attempt to breathe during these pauses like in OSA, where gasping is often witnessed. Patients with CSA and ventricular dysfunction demonstrate greater cardiac electric instability when compared with patients without CSA.

In the context of the current epidemics of obesity, hypertension, atrial fibrillation, and heart failure, the consequences of both OSA and CSA are likely to increase. However, numerous hurdles exist in establishing best practices in regard to the relationship between sleep apnea and cardiovascular disease. These challenges include:

The general absence of any structured sleep medicine education in cardiovascular training programs
The logistic and economic obstacles of diagnosing and treating sleep apnea
Widespread comorbidities, including obesity, that obscure clear understanding of any independent cardiovascular consequence of sleep apnea
Treatment options that are varied, predominately device based, and not easily tolerated, particularly in patients with CSA
The absence of robust longitudinal interventional studies addressing whether treating sleep apnea confers any tangible benefit in terms of cardiovascular events

Source: Somers, VK, White DP, Amin R, et al. 2008. Sleep Apnea and Cardiovascular Disease: An American Heart Association/American College of Cardiology Foundation Scientific Statement from the American Heart Association Council for High Blood Pressure Research Professional Education Committee, Council on Clinical Cardiology, Stroke Council, and Council on Cardiovascular Nursing. Circulation; 118: 1-32.

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