P006 The Impact of Growth Hormone Treatment on Cardiovascular Control in Children with Prader-Willi syndrome

BACKGROUND: Many children with Prader-Willi syndrome (PWS) are treated with growth hormone (GH), which may increase the risk of obstructive sleep apnoea. Children with PWS also have impaired cardiac autonomic control due to reduced parasympathetic activity, which may increase cardiovascular risk, however the impact of GH on autonomic control is yet to be elucidated. METHODS: Pre- and post-GH polysomnographic data in 38 children (aged 0-18 years) were retrospectively collected. Spectral analysis of heart rate variability (HRV) was used to determine total, low frequency (LF, sympathetic and parasympathetic activity), high frequency (HF, parasympathetic activity) power and LF/HF (sympathovagal balance). Data were compared with Wilcoxon Signed Rank Test and Spearman Rank Order Correlation analysis and are presented as median [interquartile range]. RESULTS: HRV data were significantly correlated with age so children were grouped into those <2 years (n=22) and >2 years (n=16). There were no significant differences in the obstructive or central apnoea-hypopnoea indexes between pre- and post-GH studies in either group. In children <2 years, there were no significant differences in total power, LF, HF and LF/HF between studies. In children >2 years, total power (1912.2 ms2, [920.2, 4916.1] vs 1010.2 ms2 [416.0, 2828.7), LF (434.0 ms2 [247.0, 1340.7] vs 278.9 ms2 [83.4, 676.0]) and HF (986.0 ms2 [321.8, 2400.6] vs 414.4 ms2 [146.2, 1152.7]) were lower (p< 0.01 for all) post-GH. CONCLUSIONS: Our results demonstrate that GH decreases both sympathetic and parasympathetic activity during sleep in children >2 years, which could further increase cardiovascular risk.