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.
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].
Treatment with nCPAP is associated with an improvement in peak VO2 and heart rate recovery in patients with OSA.