P095 Heart Rate Variability during Sleep in Paroxysmal Atrial Fibrillation patients with and without Obstructive Sleep Apnoea

Introduction Physiological studies have demonstrated the importance of the autonomic nervous system in mediating acute apnoea-induced atrial fibrillation (AF). We aimed to compare Heart Rate Variability (HRV) markers of autonomic function in paroxysmal atrial fibrillation (PAF) patients with and without obstructive sleep apnoea (OSA). A secondary aim was the analysis of ectopic beats in these groups. Methods Nocturnal ECG traces from 89 PAF patients who underwent in-laboratory polysomnography were included. After identifying ectopic beats in the ECGs, periods of arrhythmia as well as sleep apnoea events were excluded. HRV time and frequency domains were reported by sleep stage (REM vs Non-REM) for patients with and without OSA. Results Frequency domain analysis of HRV during non-REM sleep in PAF patients with OSA showed increased cardiac parasympathetic modulation (HF-nu: 39.13 ± 15.74 vs 47.98 ± 14.60, p = 0.008*) and reduced cardiac sympathetic modulation (LF/HF ratio: 2.05 ± 2.02 vs 1.17 ± 0.98, p = 0.007*). Results remained significant after adjusting for age, sex and BMI (adjusted p values 0.024 and 0.018 respectively). PAF patients with severe OSA (AHI ≥ 30/hr) had more AF beats and Ventricular Ectopic Beats than those without severe OSA (22.7 ± 42.8% vs 3.7 ± 17.9%, p = 0.006*, 1.7 ± 3.8 vs 0.3 ± 0.9%, p = 0.004* respectively). Conclusions This is the first study of HRV in AF patients with and without OSA. It suggests a chronic increase in parasympathetic nervous modulation and relative reduction in sympathetic modulation in PAF patients with OSA.