Vernakalant is a promising novel antiarrhythmic intravenous drug for the rapid conversion of atrial fibrillation to sinus rhythm. It blocks several ion currents important in cardiac action potential including IKr. Its difference to traditional antiarrhythmic drugs is a preferential effect on the atria, achieved by an inhibition of repolarizing potassium ion currents I(Kur), which is atrial-specific, and I(to), predominantly affecting atrial repolarization, as there is little atrial plateau potential. Furthermore vernakalant blocks frequency- and voltage-dependent sodium ion currents (I(Na)). Thus rapid action potentials in atrial fibrillation are particularly targeted by vernakalant: this leads to a conversion rate to sinus rhythm in about 50 % of recent-onset attacks (less than 7 days) of atrial fibrillation. Age, gender, organ function and concomitant medication seem to have no clinically significant influence on the pharmacokinetics of vernakalant. The number of patients included in the studies is still too small to provide a definitive answer on its cardiac toxicity. However, a demonstrated tendency towards proarrhythmia and little experience with this new drug demands precaution even after it has been officially approved.
