CARBAMAZEPINE-INDUCED SINUS NODE DYSFUNCTION AND ATRIOVENTRICULAR-BLOCK IN ELDERLY WOMEN

We report on four elderly women in whom carbamazepine was suspected of inducing sinus node dysfunction (3 patients) and atrioventricular blo ck (1 patient). Patients were treated with carbamazepine, 200 to 600 m g a day, for trigeminal neuralgia (n= 3) or epilepsy (n = 1). After 1 to 16 months of carbamazepine therapy, these patients were admitted to our emergency roam because of bradyarrhythmia. Their conduction distu rbances on electrocardiographic monitoring disappeared immediately aft er the cessation of carbamazepine intake. Provocation tests were perfo rmed on three patients. Because of renal insufficiency, one patient co uld not undergo the provocation test. Her carbamazepine clearance was markedly decreased. Carbamazepine induced sinus arrest in two patients within 48 hours after intake, but did not induce atrioventricular blo ck in the remaining patient. In two patients, computer simulation of c arbamazepine pharmacokinetics was performed and disclosed a clear-cut relationship between the plasma concentration of carbamazepine and the frequency of sinus arrest. During the test, the maximum plasma carbam azepine concentration in these two patients did not exceed the therape utic range. However, it did exceed the range in the one with a negativ e test. Our results suggest that careful monitoring of ECG and plasma drug concentration is required with carbamazepine therapy, especially in elderly women.