CPAP does not modify exercise-derived autonomic responses in nonsleepy patients with coronary artery disease and obstructive sleep apnea

BACKGROUND: Obstructive sleep apnea (OSA) is associated with autonomic dysfunction and increased cardiovascular risk, but the effects of continuous positive airway pressure (CPAP) on exercise-derived autonomic responses in patients with coronary artery disease (CAD) remain unclear. METHODS: This study included nonsleepy patients (Epworth Sleepiness Scale score <10) with CAD and OSA (apnea-hypopnea index ≥15 events/h) enrolled in the RICCADSA randomized controlled trial. Of 244 patients randomized at baseline, 204 (CPAP n = 100; no-CPAP n = 104) completed bicycle ergometer exercise testing at both 3 and 12 months and were included. The primary outcome was the change in 1-min heart rate recovery (HRR1) from 3 to 12 months; secondary outcomes included changes in 4-min heart rate recovery (HRR4), chronotropic response, and post-exercise recovery time. Longitudinal changes were analyzed using linear mixed-effects models adjusted for sex, body mass index (BMI), diabetes, and β-blocker use. RESULTS: HRR1 remained stable from 3 to 12 months in both groups (approximately 22-23 bpm), with no CPAP or time × treatment effects. HRR4 showed no differential change, remaining around 46-47 bpm. Chronotropic response was unchanged (chronotropic index approximately 0.74-0.76 in both groups). Exercise workload and peak heart rate remained stable over time and did not differ between groups. Post-exercise recovery time shortened significantly in the overall cohort (by approximately 0.3 min from 3 to 12 months) but was not CPAP-specific. Higher BMI and β-blocker use were independently associated with impaired late HRR and chronotropic response. CONCLUSIONS: In nonsleepy patients with CAD and OSA, CPAP does not modify exercise-derived autonomic or chronotropic responses, underscoring the need for complementary strategies targeting metabolic burden and cardiovascular conditioning.