June 12, 2013
Sudden Cardiac Death Risk Greater In People With Obstructive Sleep Apnea
Lawrence LeBlond for redOrbit.com - Your Universe Online
Prolonged obstructive sleep apnea has been found to cause a number of other health-related problems, such as hypertension and liver function impairment. More recently, sleep apnea has also been associated with asthma and Alzheimer´s disease.
A new study in the Journal of the American College of Cardiology (JACC) is now reporting that a moderate case of obstructive sleep apnea can significantly increase a person´s risk of sudden cardiac death. The finding is based on the largest study of its kind by researchers with the Mayo Clinic in Rochester, Minnesota.
Sleep apnea is generally diagnosed when a person stops breathing for 10 seconds or longer at least five times per hour during sleep. Symptoms of sleep apnea usually include loud snoring, choking and/or gasping for breath while sleeping. Sleep apnea is also associated with morning drowsiness and excessive daytime sleepiness. Many people affected by sleep apnea have overactive bladders and can find themselves awakening often during the night to go to the bathroom.
According to the National Institutes of Health´s National Heart, Lung and Blood Institute (NHLBI), obstructive sleep apnea affects more than 12 million Americans. Nearly half of those who are afflicted with this condition are overweight and many go undiagnosed. The disorder affects men more than women, and although it can occur at any age, it typically affects people as they get older. Those who smoke and have diabetes are also more likely to have sleep apnea.
"The prevalence of obstructive sleep apnea in Western populations is high and will likely only continue to grow given the obesity epidemic and direct relationship between obesity and sleep apnea," said lead author Apoor Gami, MD, MSc, FACC, a cardiologist at Midwest Heart Specialists — Advocate Medical Group in Elmhurst, Illinois.
The researchers used results from a previous study where they discovered people with sleep apnea more frequently died from cardiac causes during the hours of 10 p.m. to 6 a.m.
For the new study, the team followed 10,701 subjects for an average of 5.3 years. Gami and colleagues looked for incidents of resuscitated or fatal sudden cardiac death. During that time, 142 patients experienced sudden cardiac death. Of the incidences accounted for, the most common indicators were patients aged 60 years or older, having 20 apnea episodes per hour and having oxygen saturation levels below 78 percent.
Low oxygen saturation occurs when air cannot flow normally into the lungs, which occurs during sleep when a sleep apnea patient´s airway becomes obstructed. As a result, the blood oxygen level drops, causing low oxygen saturation. A drop to below 78 percent increases sudden cardiac death by 80 percent, according to the study.
The overall risk of sudden cardiac death does not simply shift from typical daytime hours to nighttime hours, but people with obstructive sleep apnea are more likely to suffer sudden cardiac death during nighttime hours than those without sleep apnea, the study noted.
"Treating sleep apnea in one person can improve the quality of life of both bed partners and may have the added benefit of helping to prevent cardiovascular disease," said Virend K. Somers, MD, PhD, FACC, senior author on the study and a professor of medicine at Mayo Clinic College of Medicine in Rochester, Minn. "If the spouse sees the bed partner stop breathing repeatedly during sleep, this is an important clue that he or she probably has sleep apnea."