Exercise-derived autonomic recovery during CPAP therapy in coronary artery disease patients with OSA: Does sleepiness matter?

BACKGROUND

Obstructive sleep apnea (OSA) is highly prevalent in patients with coronary artery disease (CAD) and is associated with autonomic dysfunction and adverse cardiovascular outcomes. Exercise-derived autonomic markers provide an integrated assessment of cardiovascular autonomic regulation. Whether baseline OSA severity and longitudinal autonomic adaptation during continuous positive airway pressure (CPAP) therapy are influenced by daytime sleepiness remains unclear.

METHODS

In the RICCADSA cohort, 322 patients with CAD were studied, including CPAP-treated patients with moderate-to-severe OSA classified as non-sleepy (Epworth Sleepiness Scale [ESS] <10; n = 100) or sleepy (ESS ≥10; n = 130), and a non-OSA reference group (apnea-hypopnea index [AHI] <5 events/h; n = 92). Standardized exercise testing was performed at 3 and 12 months. Outcomes included heart-rate recovery at 1 and 4 min (HRR1, HRR4), chronotropic response, and post-exercise recovery time. Baseline associations with AHI were examined using multivariable linear regression, and longitudinal changes were assessed using linear mixed-effects models.

RESULTS

Higher baseline AHI was independently associated with lower HRR1, HRR4, and chronotropic response (all p < 0.05), independent of ESS. During follow-up, HRR1, HRR4, and chronotropic response showed no meaningful change, whereas recovery time shortened significantly over time (p < 0.01). Longitudinal trajectories did not differ by sleepiness status.

CONCLUSIONS

OSA severity is linked to impaired autonomic capacity, while CPAP therapy selectively improves autonomic recovery dynamics. Sleepiness does not modify these adaptations, suggesting that CPAP enhances autonomic flexibility rather than reversing established autonomic impairment.