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Sleep disorder ups risk of heart problem recurrence

By Alison McCook

Last Updated: 2003-05-30 10:02:55 -0400 (Reuters Health)

NEW YORK (Reuters Health) - People who have a common heart-rhythm disorder may be more likely to experience a recurrence after treatment if they also have an untreated sleep disorder known as sleep apnea, new study findings suggest.

Researchers at the Mayo Clinic in Rochester, Minnesota, found that, among people treated for a heart rhythm irregularity known as atrial fibrillation, more than 8 out of 10 patients who also had untreated sleep apnea experienced a return of their atrial fibrillation within one year.

In contrast, only around 4 out of 10 people treated for atrial fibrillation who had sleep apnea but received treatment for the condition saw their heart rhythm problem return.

Atrial fibrillation is a relatively common form of arrhythmia. Although not the most deadly type of irregular heart rhythm, atrial fibrillation puts patients at risk of potentially life-threatening blood clots, due to the pool of blood that slowly gathers in the atria when those chambers become unable to contract regularly.

According to the report published in the American Heart Association's journal Circulation, approximately 50 percent of people treated for atrial fibrillation who were sleep apnea-free experienced a recurrence of their heart problem one year after treatment.

"If you've got sleep apnea and you've had atrial fibrillation in the past, chances are your risk of getting it again is higher," study author Dr. Virend K. Somers told Reuters Health.

Somers noted that both sleep apnea and atrial fibrillation can pose problems for the cardiovascular system, and having both conditions may be worse than having each alone.

Although this question has not yet been investigated, "it's likely that when you put them both together, the effects may at least be additive," he said.

Study participants with sleep apnea had the most common form of the condition, known as obstructive sleep apnea. This type of sleep apnea is caused by a collapse of the throat during sleep, leading to an interruption of breathing.

During the study, Somers and his team followed a group of patients who had been treated for atrial fibrillation for one year after treatment to determine if their arrhythmia recurred. Thirty-nine of the patients had obstructive sleep apnea, but only 12 were receiving appropriate treatment for the sleep disorder.

One year after treatment for atrial fibrillation, the researchers found that the heart arrhythmia had returned in 82 percent of patients with untreated sleep apnea, 42 percent of treated sleep apnea patients, and in one-half of a group of 79 patients without sleep apnea.

In an interview, Somers explained that there are many reasons why sleep apnea may increase the risk that atrial fibrillation will occur.

During episodes of sleep apnea, the body may not get enough oxygen, and this situation can stress the heart into developing an arrhythmia, Somers said. In addition, a sleep apnea episode often increases blood pressure and causes the body to release adrenaline-like substances, both of which can lead the heart to adopt an abnormal rhythm, he noted.

Many people have atrial fibrillation, Somers said. While it would be nice to know who among them has sleep apnea, as well, diagnosing the sleep disorder can be very expensive.

However, he suggested that doctors faced with a patient with atrial fibrillation who also has some common risk factors for sleep apnea -- such as obesity, loud snoring, and excessive daytime sleepiness -- should consider the possibility of an additional problem.

"These are signs there's a reasonable chance of coexisting sleep apnea," Somers said.

Copyright 2002 Reuters.