Changes in autonomic cardiac control in patients with epilepsy after discontinuation of antiepileptic drugs: a randomized controlled withdrawal study.

The aim of this study was to assess cardiac autonomic control in patients with epilepsy before and after withdrawal of antiepileptic drugs (AEDs). The study was prospective, randomized and double blinded. Spectral analysis of heart rate variability (HRV) in 24 h ECG-registration before and after withdrawal of AEDs was used to assess autonomic cardiac control. The assessment of HRV with spectral analysis was based on sinus rhythm and normal heart beats [normal to normal beat (NN)]. Thirty-nine patients had 24 h rhythms free from any ectopic beats both before and after intervention, and were included in the analysis. Significant differences were found in the withdrawal group: filtered RR intervals for all 5 min segments of the analysis; percentage of differences between adjacent filtered RR intervals that are greater than 50 ms for the whole analysis; very low frequency power; low frequency power and high frequency power. The results demonstrate that slow withdrawal of AEDs in seizure-free patients with epilepsy on drug mono-therapy resulted in an increase in both parasympathetic and sympathetic functions, indicative of increased power amongst patients following cessation of AED treatment. As low HRV has been associated with increased mortality in patients with other diseases, this increased HRV may be beneficial.

How important is heart rate?

Mortality rises as resting heart rate increases. Patients who are less able to increase their heart rate while exercising are more likely to die than those whose heart rate does rise. The occurrence of silent ischaemic events shows a circadian distribution, with increased mortality, heart rate and systolic blood pressure early in the morning. Treatment with beta-blockers reduces the number of asymptomatic ischaemic episodes, and lowers heart rate during exercise and at rest. The ischaemic myocardium of the dog loses the ability to undergo wall thickening during exercise. Moreover, blood flow in the ischaemic subendocardium is reduced during exercise. These effects can be overcome using beta-blockers. The effects of beta-blockers in reducing heart rate are less pronounced during mental stress. Furthermore, changes in wall motion abnormalities during mental stress are not improved by beta-blockers. Treatment of patients with beta-blockers after a myocardial infarction reduces the mortality rate. The greater the reduction in heart rate, the greater the reduction in mortality.