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Sleep Disorders Linked to Arrhythmias

TUESDAY June 23, 2009 -- Older men who have severe sleep-related breathing problems are at increased risk for abnormal heart rhythms, a U.S. study finds.

The study included 2,911 men who underwent sleep testing between 2003 and 2005. Those who had more episodes of paused or shallow breathing during sleep were more likely to have two types of arrhythmias, found Dr. Reena Mehra and colleagues at Case Western Reserve University School of Medicine in Cleveland.

Obstructive sleep apnea -- which involves the partial or complete blockage of airways and is the most common type of sleep-related breathing disorder -- was associated with irregular heartbeats involving the lower chambers of the heart (ventricles). Central sleep apnea -- caused by a malfunction in brain signals that control breathing muscles -- was more strongly associated with irregular heart rhythms in the heart's upper chambers (atria).

The more severe a man's sleep-disordered breathing, the greater his risk for arrhythmia. The researchers also said "there seems to be a threshold effect such that moderate-to-severe sleep-disordered breathing confers the greatest increased odds of clinically significant arrhythmias independent of self-reported heart failure and cardiovascular disease."

The study also found that hypoxia (deficiency in the amount of oxygen reaching body tissues) may trigger ventricular arrhythmia in older men. In addition, the "strong associations between central sleep apnea and atrial fibrillation [arrhythmia originating in the heart's upper chambers] suggest that central sleep apnea may be a sensitive marker of underlying abnormalities in autonomic or cardiac dysfunction associated with atrial fibrillation."

Further studies are needed to look at the impact of treatments for sleep-disordered breathing on cardiac outcomes, the researchers concluded.

The study appears in the June 22 issue of the Archives of Internal Medicine.

More information

The U.S. National Heart, Lung, and Blood Institute has more about sleep apnea.

Posted: June 2009


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