Amiodarone-induced polymorphous ventricular tachycardia.

Five cases of amiodarone-induced polymorphous ventricular tachycardia (torsade de pointes) are presented. All patients had recurrent syncope or dizziness due to polymorphous ventricular tachycardia and in all cases the QT interval was prolonged. In two cases hypokalemia was present at the time the arrhythmia was first recorded, but in both cases polymorphous ventricular tachycardia persisted despite correction of the electrolyte imbalance. Standard treatment for polymorphous ventricular tachycardia (isoproterenol, ventricular pacing, or both) was successful in all patients, however, therapy had to be continued for 5 to 10 days, most probably because of the long elimination half-life of amiodarone.