In a study, researchers found that almost 60 percent of pacemaker patients had undiagnosed sleep apnea, which might have possibly contributed to their heart disease. This study is reported in Circulation: Journal of the American Heart Association. Moreover, more than 21 percent of the patients had severe sleep apnea, characterized by 30 or more periods of interrupted breathing each hour during sleep, said Patrick LÚvy, M.D., Ph.D., senior author of the study and a professor physiology at Grenoble University in Grenoble, France.
'Because of the excessive prevalence of undiagnosed sleep apnea we found, it could be recommended that all patients referred for a pacemaker should first be screened for sleep apnea. Sleep apnea is known to increase risk of cardiovascular disease,' LÚvy said.
In the study, researchers investigated the prevalence and consequences of undiagnosed sleep apnea in pacemaker patients. Ninety-eight French, British and Belgian pacemaker patients (average age 64) who were undiagnosed with sleep apnea underwent laboratory monitoring of their sleep. Abnormally slow heart rhythms (Bradycardic rhythm disorders) are common among patients with obstructive sleep apnea.
Twenty-nine patients had received pacemakers to treat heart failure, which means that the heart cannot efficiently pump blood. Thirty-three patients had a high degree atrioventricular block or AV block, which is a blocked electrical signal from the heart's upper chamber (atria) to the pumping chamber (ventricle). Thirty-six had sinus node disease, in which a heart chamber pumps too fast or too slow.
Researchers screened the patients with the Epworth Sleepiness Scale and polysomnography, a device that records breathing and sleep. The pacemakers were programmed to pace the heart at a uniform lower pacing rate. Sleep apnea was defined as an apnea hypopnea (abnormally shallow breathing) index of 10 or more an hour.
Fifty-seven patients (59 percent) had sleep apnea and 21 (21 percent) had severe sleep apnea, LÚvy said. Half of the patients with heart failure, 68 percent of patients with AV block, and 58 percent of patients with sinus node disease had sleep apnea.
Previous studies have found that about one fifth of the general population has sleep apnea, he said.
Researchers said they couldn't determine if the sleep apnea preceded the pacemaker implantation or if it developed after the initiation of pacemaker therapy. LÚvy noted that successfully treating sleep apnea with weight loss, smoking cessation and continuous positive air pressure (CPAP) might eliminate the need for pacing. But additional studies are needed to define optimal treatment strategy for pacemaker patients who have obstructive or central sleep apnea.