ROCHESTER, MINN—The incidence of atrial fibrillation (AF) has increased dramatically in the past several decades. Research has suggested that AF occurs more often in patients with obstructive sleep apnea (OSA), but whether treatment of OSA affects AF recurrence following cardioversion had not been determined. New evidence now demonstrates that patients with untreated OSA have a higher recurrence of AF than do those whose OSA is treated.[1]

Thirty-nine patients with AF or atrial flutter who were referred to the Mayo Clinic Cardioversion Center in Rochester, Minnesota, were studied; all had undergone a formal sleep study and had been given a diagnosis of OSA. Twenty-seven of these patients either were not using continuous positive airway pressure (CPAP) or were not compliant with therapy; these patients were considered the untreated group. The remaining 12 patients (the treated group) used CPAP appropriately.

Information on recurrence of AF was gathered 12 months after initial successful cardioversion. The same information was also obtained for 79 control patients who had never undergone a formal sleep study.

AF RECURS IN UNTREATED OSA

At 12 months, AF had recurred in 82% of the untreated or inappropriately treated patients with OSA, compared to 42% of the treated group and 53% of the controls. In the untreated OSA group, the mean nocturnal fall in oxygen saturation was 8% in patients without recurrent AF, compared with 18% in those with recurrences.

Interestingly, patients in the untreated OSA group had lower body mass index, less likelihood of a history of hypertension, and better functional capacity—all of which should have reduced their risk of AF recurrence. According to the authors, this indicates that other factors may have been responsible for the high rate of recurrent AF. For example, evidence links the hypoxemia that occurs during OSA to pulmonary vasoconstriction and to increased pulmonary artery pressure.

Virend K. Somers, MD, PhD, one of the study authors and a Professor of Medicine (Cardiology) at the Mayo Clinic, said that screening all AF patients for OSA is not feasible. However, he added, “If OSA could be treated on a comprehensive basis, it would be helpful. Unfortunately, it is not diagnosed as often as it should be.” In addition, he noted, “Compliance with treatment (CPAP) is a problem. Many patients cannot tolerate it.

“The present findings need to be confirmed in a larger study,” Dr. Somers said. “Hopefully, this could then bring about changes in the way patients with OSA are treated.”

—Gale Jurasek