More than 2 million Americans have atrial fibrillation, a condition in which part of the heart quivers instead of contracting regularly. With blood puddling in the heart, a clot can form and travel to the brain to cause a stroke. Atrial fibrillation often occurs in people with obstructive sleep apnea, temporarily stopping breathing while they sleep, which afflicts some 40 percent of obese adults. Treating sleep apnea can help reduce the risk of atrial fibrillation coming back. Researchers at the Mayo Clinic looked at atrial fibrillation patients to find out how many of them have obstructive sleep apnea.
What the researchers wanted to know: How many atrial fibrillation patients have obstructive sleep apnea?
What they did: The researchers looked at 151 patients who came to the Mayo Clinic to get their fibrillating atria electric-shocked into proper behavior (a procedure called cardioversion). They were compared with 312 people who were referred to a cardiologist but had never had atrial fibrillation. All were given a questionnaire to determine whether they had obstructive sleep apneathe questions are mostly about snoring and sleepiness during the day. The researchers sent a letter to patients who were found to have obstructive sleep apnea, suggesting they see a doctor about it.
What they found: Nearly half of the patients with atrial fibrillation had obstructive sleep apnea, compared with only 32 percent of the other heart patients. Atrial fibrillation was more strongly associated with obstructive sleep apnea than the traditional risk factors, such as neck circumference and high blood pressure, which were also considered in this study. The authors speculate that the nightly interference with air flow and the oxygen content of your blood could cause atrial fibrillationor that atrial fibrillation causes obstructive sleep apnea in some cases, by sending impulses to the parts of the nervous system that control breathing.
What the study means to you: People with atrial fibrillation might consider getting checked for obstructive sleep apnea; treating it may help their hearts.
Caveats: The researchers used a questionnaire to diagnose sleep apnea, while the best diagnosis is actually having someone sleep in a lab all night. (But they double-checked by having some people sleep in the lab and found the questionnaires were accurate.)
Find out more: The American Heart Association's page on atrial fibrillation includes links to explanations of atrial fibrillation and cardioversion. An explanation of sleep apnea, from The Sleep Channel: www.sleepdisorderchannel.net/osa/
Read the article: Gami, A.S., et al. "Association of Atrial Fibrillation and Obstructive Sleep Apnea." Circulation. July 27, 2004, Vol. 110, No. 4, pp. 364-367.
Abstract online: http://circ.ahajournals.org