That gasping wakeup is a sign of sleep apnea, in which the lungs are not getting enough air. And a new study finds a close association between sleep apnea and atrial fibrillation, a heartbeat abnormality that can be fatal.
The risk of recurrent atrial fibrillation is doubled in people with untreated sleep apnea, says a Mayo Clinic study reported in the May 27 issue of Circulation.
In the Mayo study, obstructive sleep apnea, in which there is a blockage of the airway, was the single factor most closely associated with recurrence of atrial fibrillation.
"To our knowledge, this is the first study showing that untreated obstructive sleep apnea is associated with an increased risk of recurrent atrial fibrillation and that the risk is not explained by other factors," says a statement by Dr. Virend Somers, the Mayo Clinic cardiologist who led the study.
Atrial fibrillation makes the upper chambers of the heart flutter uselessly, rather than pumping blood. It can cause heart failure, heart attack or stroke. Drugs or CPAP -- continuous positive airway pressure, using a machine to force air into the nasal passages -- can help treat it, but it comes back in more than half of all patients within a year.
"Cardiologists are now awakening to the importance of identifying and treating sleep-disordered breathing in their patients," says Dr. Barbara Phillips, director of the University of Kentucky Sleep Disorders Center and a spokeswoman for the National Sleep Foundation.
The Mayo study followed 79 people treated for atrial fibrillation who had not been diagnosed with sleep apnea and 39 patients with both fibrillation and sleep apnea. Of the 39 apnea patients, 27 got either no treatment or inadequate treatment for the condition. After a year, fibrillation recurred in 22 (or 81 percent) of the apnea patients with untreated apnea and five (or 42 percent) of the apnea patients who got adequate treatment.
This is an important study because it is the first to describe the results of treating sleep apnea in atrial fibrillation patients, Phillips says. "CPAP made a big difference for those patients who used it," she says.
Somers says the results are particularly important because obesity increases the incidence of sleep apnea, and Americans are getting fatter. The epidemic of obesity in this country could be behind the rising incidence of sleep apnea, which "may contribute to the dramatic increase in atrial fibrillation, which has nearly tripled in the past three decades," Somers says in the statement.
"Appropriate treatment for those with both conditions is CPAP first," Phillips says. "Not only can it help a fibrillation, it improves blood pressure, reduces the risk of heart attacks, reduces other cardiac arrhythmias, and improves heart function in patients with heart failure."
Many patients with atrial fibrillation should be screened for sleep apnea, Somers says. Leading candidates for screening are those who are obese, whose spouses say they snore loudly, or have been seen to stop breathing at night or are constantly sleepy during the day.