Moricizine-induced proarrhythmia.

Moricizine is a Class I antiarrhythmic drug currently approved for the treatment of life-threatening ventricular arrhythmias. The drug has received significant attention because of its role in the Cardiac Arrhythmia Suppression Trial. Previous data suggested that the agent has a relatively low proarrhythmic potential. This may lead clinicians to use the drug empirically for less significant ventricular arrhythmias. We report a case of life-threatening late proarrhythmia caused by moricizine and comment on our experience with this agent. We feel that this drug has significant proarrhythmic potential and should not be used empirically to treat ventricular ectopy especially in patients with underlying structural heart disease.