Abstracts

Rationale: Epilepsy patients have an increased risk of Sudden Unexplained Death from Epilepsy (SUDEP). One mechanism includes arrhythmias induced by seizures due to a dysregulation of autonomic tone. This study evaluated the effect of non-invasive measures of Heart Rate Variability (HRV) in well controlled (WC) and poorly controlled (PC) epilepsy patients. In different disease states (post myocardial infarct, Diabetes, etc.) lower measures of HRV indicate increase morbidity.Methods: Eighty-six patients aged 2-21 years old were included in the analysis. Patients were divided into Normal (NL; n=30), WC (n=31) and PC (n=25) groups. All patients were admitted for a minimum of 24 hours in the Epilepsy monitoring Unit (EMU) at SUNY Downstate. Electrocardiographic data was extracted from the Video EEG file using the Librasch program and analyzed using Kubios HRV software (Kubios HRV, Kuopio, Finland). Kubios was used to calculate time- and frequency-domain metrics of HRV for each R-R series during the following epochs: at least one hour while patient was awake and one hour while patient was asleep. A paired t-test was used to compare each metric taken while awake to sleep (A?S). A student t-test was used to compare metrics between groups.Results: Of the eighty-six patients included in this study there was no significant difference in the age or sex of the patients in each group. Time domain and frequency domain measures were compared between Awake and Sleep (A ? S) for each patient. There was an expected increase in the Mean RR and decrease in Mean HR from A?S in all groups (p<0.001). The RMSDD showed a significant increase in the NL group (47.5 4.2 ? 69.8 9.2; p<0.001), however did not show any significant change in the WC group (49.4 5.0 ? 54.0 5.2; p=0.666) or PC group (51.6 4.5 ? 62.3 9.8; p= 0.187). The frequency domain metrics include percent very low frequency (pVLF), percent low frequency (pLF), percent high frequency (pHF) and the ratio of LF/HF. The pVLF decreased from A?S in the NL group (p<0.001) and WC group (p=0.023) but no change was seen in the PC group (p=0.297). The pLF decreased in the NL (p=0.021) and PC (p=0.005) groups but had no significant change in the WC group (p=0.178). The pHF increased and LF/HF ratio decreased from A?S in all groups (p<0.05). The overall change in pHF from A?S was decreased in the WC (-8.6 2.3; p=0.02) and PC (-6.7 3.1; p=0.006) groups when compared with NL (-20.3 3.5). Also, the difference in LF/HF from A?S was smaller but not significant in the WC group (0.46 0.2; p=0.105) and significantly smaller in the PC group (0.35 0.1; p=0.017) when compared to NL (0.77 0.11). Conclusions: The results of this study demonstrate an overall decrease in HRV changes from the awake to sleep state in our epilepsy patients. This may represent overall restricted autonomic flexibility in our population of patients as demonstrated by smaller changes in RMSDD, pHF and LF/HF metrics of HRV when comparing A?S. Poor elasticity of the autonomic nervous system may be a factor in increased risk for SUDEP.