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 HF(nu,)P<0.001) and an increase in sympathetic tone (increased LF(nu) 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.