Sinus node dysfunction: an adverse effect of lacosamide.

Lacosamide, a recently introduced antiepileptic drug, acts by enhancing the slow inactivation of voltage-dependent sodium channels. Cardiac conduction disturbances, namely atrial fibrillation and atrioventricular block, have been reported in patients with epilepsy. We report a patient with drug-resistant focal epilepsy who developed asymptomatic sinus node dysfunction following lacosamide use, which resolved on stopping lacosamide. This is the first report of sinus node dysfunction associated with lacosamide therapy.