Carbamazepine and the QTc interval: any association?

ABSTRACT

Objective: To determine whether carbamazepine monotherapy in epilepsy patients is or is not associated with prolongation of the QTc interval. Methods: This case-control study enrolled 100 consecutive patients with generalized tonic-clonic seizures. Fifty patients were already taking carbamazepine for a variable time, and the rest (n=50) were not on any antiepileptic drug. The QTc interval was calculated after doing a resting 12-lead ECG examination on a single occasion. Results: Of the 50 patients who had received carbamazepine, 11 patients displayed prolongation of their QTc interval, while 8 patients out of the 50 in the control group had QTc interval prolongation after correction for gender; p value =0.49, OR 1.36, 95% CI 0.54-3.29. Conclusion: This study demonstrated no statistically signifi cant association between carbamazepine monotherapy and prolongation of the QTc interval. Carbamazepine does not seem to prolong the QT interval when used as monotherapy for epilepsy. The presence of prolonged QTc interval in such patients should prompt a search for co-factors that prolong this interval, such as multiple medications, electrolytes disturbances, structural heart disease, and congenital long QT interval syndromes.