Sustained effect of continuous positive airway pressure on baroreflex sensitivity in congestive heart failure patients with obstructive sleep apnea

Background Patients with either heart failure or obstructive sleep apnea have a reduced baroreflex sensitivity for heart rate, a sign of poor prognosis. We previously demonstrated that nocturnal application of continuous positive airway pressure to heart failure patients with obstructive sleep apnea increased baroreflex sensitivity acutely, but it is not known whether these effects persist into wakefulness. Objective To determine whether treating obstructive sleep apnea in heart failure patients with continuous positive airway pressure improves baroreflex sensitivity during wakefulness. Methods Spontaneous baroreflex sensitivity was assessed during wakefulness in 33 heart failure patients (left ventricular ejection fraction <= 45%) with obstructive sleep apnea (apnea-hypopnea index >= 20). Subsequently, baroreflex sensitivity was reassessed 1 month after patients were randomly allocated to nocturnal continuous positive airway pressure treatment or no treatment (control). Results Compared with the 14 control patients, the 19 continuous positive airway pressure-treated patients experienced a greater increase in baroreflex sensitivity [median, (25%, 75%)] [from 5.4 (2.2, 8.3) to 7.9 (4.4, 9.4) ms/mmHg; P=0.01] and left ventricular ejection fraction (P < 0.001). In addition, daytime systolic blood pressure and heart rate decreased more in the continuous positive airway pressure group (from 122 +/- 15 to 113 +/- 12 mmHg; P=0.02, and from 66 +/- 8 to 62 +/- 8 bpm; P < 0.001, respectively) than in the control group. Conclusion Treatment of coexisting obstructive sleep apnea by continuous positive airway pressure in heart patients improves baroreflex sensitivity during wakefulness in addition to improving left ventricular ejection and lowering blood pressure and heart rate. These data indicate that the improved autonomic regulation of heart rate in heart failure patients treated for obstructive sleep apnea during sleep persists into wakefulness.