Analysis of 24-hour heart rate variations in patients with epilepsy receiving antiepileptic drugs

Objective: The goal of the study described here was to evaluate interictal heart rate variability (HRV) in young patients with epilepsy, a patient population in whom sudden unexpected death in epilepsy (SUDEP) is known to be more common. Methods: Twenty-four-hour ambulatory ECG Holter recordings of 37 patients (15-40 years old) and 32 healthy controls were compared. Results: All of the time domain indices (SDNN, SDANN, RMSSD, and HRV triangular index) were significantly suppressed (P < 0.001), and there was a marked reduction in parasympathetic tone (reduced HFnu, P < 0.001) and an increase in sympathetic tone (increased LFnu and LF/HF ratio, P < 0.001) in the patient group. Stepwise linear regression analysis revealed that polytherapy and epilepsy duration > 10 years were independent variables associated with a reduction in SDNN. Conclusion: Our data suggest that the major determinants of suppressed SDNN are polytherapy and epilepsy duration > 10 years. Analysis of spectral measures of frequency domain indices suggests that an increased sympathetic tone in association with a decreased parasympathetic tone may constitute the mechanism underlying SUDEP in young people with epilepsy. (C)2010 Elsevier Inc. All rights reserved.