O046 Autonomic Control of Heart Rate in Growth Hormone Naïve Children with Prader-Willi Syndrome

Abstract Background Adults with Prader Willi syndrome (PWS) have an increased risk of cardiovascular morbidity and mortality, which may be due to impaired autonomic control. Heart rate variability (HRV) has been used in different populations as a strong and independent predictor of cardiac mortality and diseases. Studies have not assessed cardiovascular control in children with PWS during sleep while accounting for sleep disordered breathing severity which affects HRV. Methods Overnight electrocardiogram recordings during routine sleep studies in children with PWS pre-growth hormone treatment (n=48) and typically developing (TD) children matched in age, obstructive and central apnoea hypopnoea index, body mass index and sex were collected. Power spectral analysis determined HRV for total, low frequency (LF, sympathetic and parasympathetic activity), high frequency (HF, parasympathetic activity) power and LF/HF (sympathovagal balance) during N2, N3, REM and total sleep. Linear mixed-effects modelling adjusting for age, and obstructive and central sleep apnoea severity compared HRV parameters between children with PWS and TD children. Results Children with PWS had significantly reduced LF power in N2, REM and total sleep when compared to TD children (p<0.05 for all). Conclusions The significant reduction in LF power indicates children with PWS have reduced parasympathetic and sympathetic activity, which may increase cardiovascular risk, however longitudinal studies following children into adulthood are required to confirm this.