Sleep apnea: a new indication for cardiac pacing?

In the general adult population, prevalence of sleep apnea syndrome reaches 4% in men and 2% in women. Continuous positive airway pressure is the most efficient treatment. At the present time, although severe atrial bradycardias could occur during sleep apnea episodes, cardiac pacing has not been demonstrated as an efficient treatment for those bradycardias. Treating sleep apnea generally reduces the number of bradyarrhythmias. However, recent studies reported a beneficial effect of atrial pacing on the sleep apnea burden. The mechanisms rely on two phenomena: first to counteract nocturnal hypervagotonia, and second to treat heart failure. By increasing the heart rate, cardiac output improves, which mitigates pulmonary subedema. Consequently, stimulation of the pulmonary afferent vagal fibers is diminished, which reduces central sleep apnea incidence. During nocturnal hypervagotonia, snoring and obstructive apnea episodes are increased, mainly due to an excessive muscular relaxation of the upper airway area inducing cyclical substantial decreases in the airway caliper. In patients with a low heart rate, atrial pacing can counteract hypervagotonia by enhancing the sympathetic tone and modifying the degree of vigilance. Accordingly, in the near future, sleep apnea treatment might potentially rely on atrial pacing in bradycardic patients with hypervagotonia (with or without heart failure). The role of the physician would then be not only to diagnose sleep apnea, but also to identify potential responders to cardiac pacing.