Effect of the class III antiarrhythmic drug nibentan in vagotonic atrial fibrillation

: Nibentan, the class III antiarrhythmic drug, was experimentally investigated in anaesthetized dogs using the model of vagotonic atrial fibrillation. Under the conditions of vagus nerve stimulation, nibentan retained the ability to prolong the ventricular repolarization and increase the effective refractory periods and to maintain the frequency-independent action on the effective refractory periods of the atrium. At the same time, nibentan did not affect conduction via the His-Purkinje system and prevented bradycardia induced by vagus stimulation. The drug was found to depress the conduction in atrium, this effect being retained on the background of vagus nerve stimulation. Nibentan has proved to be effective in preventing the vagotonic atrial fibrillation.