Life-threatening amiodarone-induced thyrotoxicosis - Personalized approach to radical treatment

Objective: Amiodarone is an iodine-rich molecule and an effective antiarrhythmic drug. It is a first- line treatment for patients with life-threatening ventricular arrhythmias and for prevention in patients at high risk. The use of amiodarone may cause serious adverse effects such as pharmacotherapy-resistant, life-threatening amiodarone-induced thyrotoxicosis (AIT)leading to rapid deterioration of the patient's condition. According to the European Thyroid Association (ETA) guidelines, emergency thyroidectomy is the first-line treatment option in these cases. ; however, is not always feasible in the clinical setting due to the high anesthetic risk. We aimed to assess the clinical course and results of urgent thyroidectomy and 131-I therapy in patients with severe AIT with worsening of cardiac status. Methods: Retrospective analysis of the clinical course and outcomes of life-threatening AIT refractory to pharmacotherapy in patients hospitalized at a tertiary endocrinology center between 2014 and 2022. Results: An electronic database search identified 75 patients hospitalized for severe AIT. At the time of AIT diagnosis, median Thyroid-stimulating hormone (TSH) concentration was 0.001 mIU/ L (range 0.001-0.35), fT4 63.2 pmol/L (range 9.0- >100), and fT3 10.2 pmol/L (range 3.8-49.3). All patients received optimal conservative treatment. Among them, 20 required urgent radical therapy due to worsening arrhythmias and/or AIT-related heart failure. In this group, 6 patients died before any radical treatment was applied, 6 underwent total thyroidectomy, while 8 patients were successfully treated with 131-I (in 6 cases after rhTSH stimulation). The median dose of 131I used for the therapy was 784MBq (range 627-860). The decision to treat with 131-I despite low but detectable 131-I uptake (median value 6 %) was made in cases of significant contraindications to anesthesia due to refractory ventricular arrhythmias, exacerbation of severe heart failure unresponsive to cardiac treatment, myocardial infarction during AIT course, massive pulmonary embolism. Conclusion: The decision regarding the optimal time and type of radical treatment of AIT refractory to pharmacotherapy is critical for patients management and should not be delayed. Urgent therapy with 131-I may be an effective therapeutic option in patients who are unsuitable for thyroidectomy due to the high risk of anesthesia.