Link Between Heart Disease, Sleep Apnea Should Be Probed
Medical researchers need to undertake large-scale studies to determine the exact relationship between heart disease and the different forms of sleep apnea, according to a joint statement from the American Heart Association and the American College of Cardiology, published online in Circulation: Journal of the American Heart Association and the Journal of the American College of Cardiology.
“There have been a number of studies on sleep apnea in the last decade, and those looking at cardiovascular diseases and their associations with sleep apnea are especially compelling,” said Virend K. Somers, M.D., D.Phil., chair of the joint statement writing committee. “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.”
Though the link between sleep apnea and heart disease is not fully understood, the committee issued the statement because of the increasing evidence, the widespread prevalence of sleep apnea, and the rising levels of obesity, particularly in young people. Obesity is a major cause of sleep apnea, and “the epidemic of childhood obesity may be changing the epidemiology of obstructive sleep apnea in children,” said Somers, who is professor of medicine and cardiovascular diseases at the Mayo Clinic in Rochester, Minn.
“We need to more clearly define the cause and effect relationship between sleep apnea and cardiovascular diseases and risk factors,” Somers said. “There is evidence that sleep apnea may be a cause of some cases of high blood pressure, but for other cardiovascular conditions, the evidence is largely circumstantial.”
The issues are more complex than the age-old “Which comes first?” debate, he said. People with sleep apnea often have other disorders, such as obesity, and people with heart disease often have additional medical issues, making it difficult to separate the role of sleep apnea in the cardiovascular disease process.
Sleep apnea has more effects than day-time tiredness. It can result in low oxygen levels, frequent arousals from sleep and chronic sleep deprivation, with consequences that persist throughout the day. It can also affect the nervous system, lead to abnormal function of cells lining blood vessels, and promote abnormal chemical responses. In the longer term, it is possible that these changes may damage the heart and blood vessels.
“For now, until we have more clear information as to who should be treated and what the benefits of treatment would be, patients should be assessed on an individualized basis,” Somers said. “Until we know the cause and effect relationship between sleep apnea and cardiovascular disease, it would be best to take a two-pronged approach and treat patients from both perspectives: in other words, treat both their sleep apnea and their cardiovascular disease.”
The statement warns that sleep apnea cases are expected to increase due to the current epidemics of obesity, high blood pressure, atrial fibrillation and heart failure in the United States.