Continuous positive airway pressure improves exercise capacity and heart rate recovery in obstructive sleep apnea

Background: There is a relationship between obstructive sleep apnea (OSA) and heart failure (HF). Peak oxygen consumption (peak VO2), heart rate recovery, and N-terminal-pro-BNP ( NT-proBNP) are strong prognostic predictors in HF. The effects of nasal continuous positive airway pressure (nCPAP) on these parameters in OSA patients are not well defined. Methods: Forty patients with newly diagnosed OSA [apnea-hypopnea index (AHI) 37 (20-65) h(-1)] underwent cardiopulmonary exercise testing for assessment of peak VO2 and heart rate recovery at one (HRR-1) and two (HRR-2) minutes after exercise termination as well as NT-proBNP measurement at baseline and after 7.9 +/- 1.4 months of effective nCPAP (nightly usage>3.5 h). The effects of nCPAP were compared in patients with mild-to-moderate (AHI<30 h(-1); n=16) vs. severe (AHI >= 30 h(-1); n=24) OSA. Results: In the group as a whole, peak VO2 (baseline: 31.9 +/- 9.3 vs. follow-up: 33.7 +/- 9.0 ml/kg/min; p=0.02) and HRR-2 [38 (32-43) vs. 42 (32-47) bpm; p=0.01] but not HRR-1 [22 (15-26) vs. 22 (16-27) bpm; p=0.16] improved from baseline to follow-up. The effect on peak VO2 was mainly driven by a trend towards an increase in patients with mild-to-moderate OSA (31.8 +/- 10.7 vs. 33.9 +/- 10.2 ml/kg/min; p=0.08), whereas an effect on HRR-1 [20 (15-23) vs. 21 (16-26) bpm; p=0.03] and HRR-2 [38 (29-42) vs. 42 (33-47) bpm; p=0.004] was observed only in those with severe OSA. NT-proBNP levels remained unchanged [21 (11-45) vs. 26 (5-52) pg/ml; p=0.6]. Conclusions: Treatment with nCPAP is associated with an improvement in peak VO2 and heart rate recovery in patients with OSA. (C) 2007 Elsevier Ireland Ltd. All rights reserved.