Sleep Apnea and Paroxysmal Atrial Fibrillation: Diurnal Patterning of Autonomic Dysfunction and Influence of CPAP...

Autonomic nervous system (ANS) dysfunction is implicated in sleep-disordered breathing (SDB) and atrial fibrillation (AF); however, diurnal patterning of ANS function in SDB is unclear. We hypothesize diurnal variation of heart rate variability (HRV) in paroxysmal AF (PAF) in SDB and alteration by continuous positive airway pressure (CPAP).

Data from the Sleep Apnea and Atrial Fibrillation Biomarkers and Electrophysiologic Atrial Triggers (SAFEBEAT) study including 7-24 days of electrocardiography (ECG), concomitant actigraphy and polysomnography at baseline and 3 months post-CPAP initiation were analyzed. Linear mixed-effects models were used to assess (1) SDB: apnea hypopnea index (AHI), hypoxia (%sleep time with SaO₂ < 90% and nadir SaO₂) and (2) diurnal average HRV in 2 domains: frequency domain (sympathovagal) with low-frequency (LF) power (LFP), high-frequency (HF) power (HFP), LF/HF ratio (LHR), and time domain with mean of normal R-R interval (MNN), standard deviation of NN intervals (SDNN), Poincare plot standard deviation short-term and long-term variability (SD1, SD2) and effect of CPAP. All results were adjusted for age, sex, race, BMI, and use of antihypertensive, antiarrhythmic, and atrioventricular nodal blockade medications.

In 44 869 5-min epochs from 109 participants with SDB and PAF, associations of AHI and LFP, nadir SaO₂ with sympathovagal measures (LFP, LHR) and time domain measures (SDNN, SD2) were observed during wakefulness. Sleep-wake interactions were observed for multiple HRV measures, with associations generally more evident during wakefulness. From baseline to follow-up after CPAP, wakefulness HRV measures showed an increase in MNN and decreases in SDNN, RMSSD, CV, SD1, and SD2. During sleep, MNN, SD2, and LHR increased.

Autonomic measures exhibited diurnal variation in moderate-severe SDB and were influenced by CPAP. Association with SDB severity was more pronounced during wakefulness, providing key insights into likelihood of sustained chronobiologic electrophysiological remodeling.