Torsade de pointes ventricular tachycardia in a hypothyroid patient treated with propafenone.

A 31-year-old female had recurring palpitations and black-outs for 13 years. Hyperthyroidism was diagnosed and electrocardiogram suggested ventricular preexcitation. Despite being treated for hyperthyroidism (which rendered the patient hypothyroid) and receiving propranolol for the arrhythmia, the palpitations persisted. Electrophysiologic testing identified the patient's arrhythmia, and demonstrated that it improved with intravenous propafenone, a new type 1C antiarrhythmic medication. After two days of oral propafenone, this initially good response was followed by episodes of Torsade de pointes ventricular tachycardia with repeated cardiac arrest. Lidocaine and isoproterenol failed to control the rhythm, and the patient was stabilized by electrical cardioversions, atrial pacing and withdrawing the propafenone. Propafenone has been used to treat Torsade de pointes, but we show that it may also cause Torsade de pointes.