Role of cardiac pacing in sleep apnea uncertain: Article reviewed: S. Garrigue, P. Bordier, P. Jais, et al., Benefit of atrial pacing in sleep apnea syndrome, N Engl J Med, 346 (2002) 404–412

Abstract

Objectives: To determine the effect of atrial overdrive pacing on sleep apnea severity in patients with sinus node dysfunction. Study design: Unblinded, cross-over study of the effect of atrial pacing on sleep apnea–hypopnea, with randomized order of study conditions (paced versus unpaced). Study population: Fifteen patients (11 men, 4 women), mean age 69 (SD 9) years, with sinus node dysfunction and permanent dual-chamber pacemakers, with polysomnographic evidence of either central or obstructive sleep apnea–hypopnea (mean apnea–hypopnea index (AHI) 27 (SD 16)). None had symptomatic heart failure, but 11 (73%) had mildly reduced left ventricular ejection fraction (40–56%). Methods: One hundred and fifty-two patients with pacemakers implanted at least one year previously for symptomatic sinus node dysfunction (including tachycardia–bradycardia syndrome) were screened for symptoms of sleep apnea. Of 47 patients identified, 26 underwent polysomnography and 15 had an apnea index >5/h and an AHI >15/h. Following the baseline polysomnogram, subjects underwent polysomnography on the subsequent two nights under the following conditions, in random order: (1) pacemaker set at a rate 15 beats/min higher than the mean heart rate of the diagnostic study (overdrive pacing phase); and (2) pacemaker rate reduced to 40 beats/min (no-pacing phase). The main outcome measure was the difference in AHI between the two pacing modes. Results: Mean nocturnal heart rate during the pacing phase was 72/min, versus 51/min during the no-pacing phase. During the no-pacing phase, AHI was unchanged from the baseline night at 28/h (SD 22). During overdrive pacing, however, the AHI was 61% lower at 11/h (SD 14). The AHI was lower on the pacing than the no-pacing night in all 15 subjects, regardless of whether the predominant type of apnea was central or obstructive. The mean central apnea index fell from 13 (SD 17) to 6 (SD 7), and the obstructive apnea index from 6 (SD 4) to 3 (SD 1). Both lowest oxyhemoglobin saturation and the percent time at saturation below 90% also improved on the pacing night. There was little difference in total sleep time between pacing and no-pacing nights; other measures of sleep quality were not reported. Conclusions: The authors conclude that atrial overdrive pacing at a relatively modest rate causes a substantial improvement in both central and obstructive sleep apnea, by mechanisms that are uncertain.