Radioiodine ablation of the thyroid to prevent recurrence of amiodarone-induced thyrotoxicosis in patients with resistant tachyarrhythmias

Amiodarone-induced thyrotoxicosis (AIT) is a common complication of amiodarone therapy. Although permanent withdrawal of arniodarone is recommended due notably to the risk of worsening of tachyarrhythmias, some patients may require the reintroduction of arniodarone several months after normalizing their thyroid function. We, retrospectively, assessed the effects of I-131 therapy to prevent recurrence of AIT in euthyroid patients requiring reintroduction of amiodarone. Subjects and methods Arniodarone was required in 10 cases of recurrent symptomatic paroxysmal atrial fibrillation (AF) and in 5 cases of ventricular tachycardia (VT) (M = 12, F = 3, mean age: 63+/-14 years). The underlying heart disease was dilated cardiomyopathy (n = 4), ischaemic heart disease (n = 4), hypertensive heart disease (n = 2), arrhythmogenic right ventricular dysplasia (n = 2) and valvulopathy (n = 1). Two patients had idiopathic paroxysmal AF. Results A mean I-131 dose of 579+/-183 MBq was administered 34+/-37 months after the episode of AIT. Arniodarone was reintroduced in 14 of 15 patients after a mean interval of 103+/-261 d. Fourteen patients developed definite hypothyroidism necessitating L-thyroxine but we observed no late recurrence of AIT. After a mean follow-up of 22+/-16 months, tachyarrhythmias were controlled in 12 of 14 patients. Conclusion I-131 therapy appears to be an effective and safe approach to prevent the recurrence of AIT in a patient requiring the reintroduction of arniodarone for tachyarrhythmias. (C) 2003 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.