Successful surgical treatment of refractory amiodarone-induced thyrotoxicosis causing tachycardiomyopathy

Abstract

Amiodarone is a well-established pharmacologic therapy used for several types of tachyarrhythmia. However, it is associated with potential adverse effects on thyroid function due to its high iodine concentration. Amiodaroneinduced thyrotoxicosis (AIT) is considered a difficult diagnostic problem that requires careful therapeutic strategy in order to balance the cardiologic and endocrine dysfunction associated with this condition. Herein, we report the case of a 52-year-old male patient who suffered from tachyarrhythmia due to paroxysmal atrial fibrillation. The patient had experienced recurring episodes of atrial fibrillation despite medical therapy with propafenone, sotalol and pulmonary vein isolation with catheter ablation. Amiodarone was subsequently administered, and temporary control of the arrhythmia was achieved. Six months after amiodarone treatment, the patient presented with uncontrollable tachycardia leading to heart failure, a condition known as tachycardiomyopathy. The thyroid function was assessed, and amiodarone-induced thyrotoxicosis was diagnosed. Unfortunately, AIT was refractory to treatment with carbimazole and cortisone and a surgical approach was decided. The patient eventually underwent a total thyroidectomy with complete control of the underlying arrhythmia, without the necessity for β-blockers. Heart failure was reversed and the patient has resumed his normal daily activities.