No abstract

Abstract-Sympathetic activation and sleep apnea are present in most patients with symptomatic systolic heart failure (HF). Acutely, obstructive and central apneas increase muscle sympathetic activity (MSNA) during sleep by eliciting recurrent hypoxia, hypercapnia, and arousal. In obstructive sleep apnea patients with normal systolic function, this increase persists after waking. Whether coexisting sleep apnea augments daytime MSNA in HF is unknown. We tested the hypothesis that its presence exerts additive effects on MSNA during wakefulness. Overnight sleep studies and morning MSNA recordings were performed on 60 subjects with ejection fraction Ͻ45%. Of these, 43 had an apnea-hypopnea index Ն15 per hour. Subjects with and subjects without sleep apnea were similar for age, ejection fraction, HF etiology, body mass index, blood pressure, and heart rate.