The nighttime breathing disorder known as obstructive sleep apnea increases a person's risk of having a heart attack or dying by 30% over a period of four to five years, according to a study presented at the American Thoracic Society 2007 International Conference, on Monday, May 21.
The more severe the sleep apnea at the beginning of the study, the greater the risk of developing heart disease or dying, the study found.
"While previous studies have shown an association between sleep apnea and heart disease, ours is a large study that allowed us to not only follow patients for five years and look at the association between sleep apnea and the combined outcome of heart attack and death, but also adjust for other traditional risk factors for heart disease," says researcher Neomi Shah, M.D., of Yale University.
"We recommend that patients who experience symptoms of obstructive sleep apnea—excessive daytime sleepiness, or snoring along with breathing pauses—consult their physician," Dr. Shah says. "There is some evidence to make us believe that when sleep apnea is appropriately treated, the risk of heart disease can be lowered."
In obstructive sleep apnea, the upper airway narrows, or collapses, during sleep. Periods of apnea end with a brief partial arousal that may disrupt sleep hundreds of times a night. Obesity is a major risk factor for sleep apnea.
The most effective treatment for sleep apnea is a tech¬nique called nasal CPAP, for contin¬u¬ous posi¬tive airway pres¬sure, which delivers air through a mask while the patient sleeps, keeping the airway open. It has proved successful in many cases in providing a good night's sleep, preventing daytime accidents due to sleepiness and improving quality of life.
The study included 1,123 patients referred for sleep apnea evaluation. They underwent an overnight sleep study to determine if they had sleep apnea. Over the next four to five years, they were followed to see how many had any heart disease events (heart attack, coronary angiography or bypass surgery) or died.
Sleep apnea triggers the body's "fight or flight" mechanism, which decreases the amount of blood pumped to the heart. Repeated episodes every night for a few years can starve the heart of enough oxygen when it is combined with the body's decreased oxygen intake due to the frequent breathing stoppages during the night, Dr. Shah says.