Continuation of amiodarone therapy despite type II amiodarone-induced thyrotoxicosis

Amiodarone is a powerful antiarrhythmic drug; however, its use may be complicated by thyrotoxicosis. When this occurs, clinicians must balance the continuation of amiodarone for antiarrhythmic purposes, and the discontinuation of treatment in order to prevent aggravation of the thyrotoxicosis. We studied the consequences of continuation or cessation of amiodarone in patients with type II amiodarone-induced thyrotoxicosis.

Consecutive patients who developed type II amiodarone-induced thyrotoxicosis between September 1997 and September 2000 were studied. Amiodarone was continued in patients with previous ventricular arrhythmia or supraventricular arrhythmia associated with severe haemodynamic changes and was withdrawn in the other patients. In patients with persistent, severe symptomatic thyrotoxicosis, corticosteroids were added to therapy.

Thirteen patients were studied (nine with previous atrial fibrillation/flutter and four with ventricular tachycardia). Amiodarone treatment was continued in ten patients, including eight patients who received corticosteroids, and was temporarily halted in three patients. All patients recovered, with no difference in the duration of thyrotoxicosis between the two groups. Corticosteroid treatment was well tolerated and seemed to hasten the return to a euthyroid state (mean of 3.7 +/- 0.7 months vs 6.3 +/- 1.7 months). No recurrence of hyperthyroidism occurred during long-term follow-up.

In patients who require amiodarone, treatment may be safely continued despite the development of type II amiodarone-induced thyrotoxicosis.