Heart rate variability in patients with epilepsy

Autonomic function was studied by the use of spectral analysis of heart-rate variability in patients with epilepsy in relation to type of epilepsy and anti-epileptic drug therapy. A total of 21 patients with juvenile myoclonic epilepsy (JME) and 21 with temporal lobe epilepsy (TLE) were included; 18 patients were treated with carbamazepine (CBZ), 16 with valproate (VPA) and seven with phenytoin (PHT). One healthy drug free control, matched for age and sex, was selected for each patient. Patients and controls underwent an ambulatory 24 h EKG. Heart-rate variability was analyzed in time and frequency domains. Patients with TLE had significantly lower S.D. of the RR-intervals, lower low frequency power and a lower low frequency/high frequency power ratio than their controls. A lower low frequency/high frequency power ratio was the only significant difference between the JME patient group and their controls. Treatment, however, may have had a considerable influence on the heart rate variability in the epilepsy patients. Patients on CBZ had significantly lower S.D. of RR-intervals, low frequency power and a low frequency/ high frequency power ratio than did their matched healthy drug free controls. The ratio of low frequency/high frequency power was also lower in patients on VPA compared with their controls, but apart from that no differences could be demonstrated between this treatment group and the controls. In conclusion, patients with epilepsy appear to have an altered autonomic control of the heart, with a reduction in some heart-rate variability measures, suggesting a decreased sympathetic tone, which may be related to the drug therapy or the epilepsy as such. Further studies are warranted to explore these changes and their possible relevance for sudden death in epilepsy.