Sleep-induced HRV changes and OSA in the ESADA cohort

<b>Introduction and Aim:</b> Obstructive sleep apnea (OSA) is associated with a higher cardiovascular risk and abnormal autonomic control can play a role in this context. Thus, heart rate variability (HRV) changes induced by sleep may help to understand the autonomic derangement in OSA. <b>Methods:</b> From the ESADA database, we selected 84 polysomnographies with 10-min ECG segments both pre- and post-dormitum in male patients who underwent a diagnostic sleep study at Sleep Disorder Centre of the Antwerp. Patients were classified as moderate, mild or severe OSA based on the Apnea-Hypopnea Index (AHI). We estimated HRV indices of vagal tone (pNN50+ and RMSSD), of sympatho/vagal balance (short term DFA), and vagal/sympatho balance (SampEn), comparing pre- vs post-dormitum (Wilcoxon paired test). <b>Results and Conclusions:</b> From pre- to post-dormitum, the vagal tone increases significantly in moderate and mild OSA only; the sympatho/vagal balance increases similarly in the three groups, see table (data are expressed as median and interquartile range). Our data suggest that in severe OSA we observe a lower increase of vagal indices in post-dormitum associated with a relative sympathetic overactivity, potentially leading, in turn, to a higher risk of cardiovascular events.