Amiodarone-induced thyrotoxicosis: a case for surgical management

Abstract

Objective: Amiodarone can cause the development of thyroid dysfunction in patients with or without previous thyroid disease. Although most cases of amiodarone-induced thyrotoxicosis (AIT) are mild, a significant number become life threatening. Because of its pharmacokinetics, simply discontinuing amiodarone provides no relief and can worsen the patient's condition. Medical management frequently fails, and many patients cannot discontinue amiodarone because of its effect against resistant arrhythmias.

Methods: This retrospective chart review of a case at a tertiary care institution presents the case of a fifty-five-year-old male with dilated cardiomyopathy and no previous thyroid disease. The patient was in normal sinus rhythm on amiodarone for control of atrial fibrillation. He experienced the acute onset of symptoms with return to atrial fibrillation resistant to cardioversion. Physical examination, laboratory tests, and imaging findings were all consistent with a diagnosis of AIT. An attempt to withdraw amiodarone resulted in severe ventricular tachyarrhythmias.

Results: Despite medical treatment, the patient's condition continued to deteriorate. Because amiodarone was the only effective drug, surgical treatment was elected. The patient underwent a total thyroidectomy and experienced no difficulties or complications. Postoperatively, the patient's condition improved, and he was successfully cardioverted.

Conclusions: Although an uncommon clinical entity, life-threatening AIT has been reported. Thyrotoxicosis can develop in any patient during or after amiodarone therapy. Medical management of this entity is extremely difficult because of the lack of a proven, consistent therapeutic armamentarium. Surgical management should be considered for patients whose conditions necessitate the continuation of amiodarone or those with severe symptoms resistant to medical therapy.