SUN-371 Challenging the Paradigm: IV Amiodarone in Thyroid Storm Without Worsening Thyrotoxicosis

Abstract Disclosure: R. Devbhandari: None. S. Tripathee: None. H. Akbari: None. M. Shah: None. A. Kang: None. R.M. Jhingan: None. Introduction: Amiodarone, a potent antiarrhythmic, is highly effective for rate control in atrial fibrillation (AF), particularly in hemodynamically unstable patients. Amiodarone-induced thyrotoxicosis occurs in 3-10% of cases due to iodine-induced hormone synthesis and follicular cell toxicity. We report a case of thyroid storm with AF, where thyroid function improved despite IV amiodarone use. Case report 34-year-old non-verbal male with Friedreich’s ataxia, quadriplegia, and paroxysmal AF presented with tachycardia and fever. On arrival, he was tachycardic with low normal blood pressure. The electrocardiogram showed atrial fibrillation. Initial labs were unremarkable. Computed tomography (CT) scan didn’t reveal any pulmonary embolism or cardiopulmonary abnormalities but raised suspicion for cholecystitis. He soon developed AF with rapid ventricular response with heart rates 200-250 bpm, refractory to IV metoprolol, and two rounds of synchronized cardioversion. He was started on IV esmolol and digoxin. Due to persistent tachycardia and hypotension precluding diltiazem use, an IV amiodarone drip was started as per cardiology recommendation. Phenylephrine was started for inotropy due to its negative chronotropic effect. The thyroid function panel revealed TSH <0.01 mIU/L (0.35-4.94), FT4 2.82 ng/dL (0.7-1.48), and T3 53.17 ng/dL (35-193). He had no prior history of thyroid disorders and CT imaging showed no thyroid abnormalities. He was suspected to have new onset hyperthyroidism with thyrotoxicosis. He subsequently developed septic shock secondary to acute acalculous cholecystitis confirmed on a hepatobiliary iminodiacetic acid scan. Echocardiography was unremarkable. Thyroid storm was suspected in the setting of acute cholecystitis and a Burch-Wartofsky score of 65. He was treated with IV hydrocortisone, oral methimazole, IV fluids, and antibiotics which along with percutaneous cholecystostomy led to hemodynamic improvement. Hydrocortisone was tapered with the continual improvement of FT4, and methimazole was continued for new-onset hyperthyroidism, with outpatient follow-up planned for further workup. Conclusion: This case highlights the potential use of IV amiodarone in thyroid storm for refractory arrhythmia despite maximal conventional management without worsening of thyrotoxicosis, as the patient’s thyrotoxic symptoms and thyroid function improved despite IV amiodarone. IV amiodarone inhibits peripheral T4 to T3 conversion which in combination with anti-thyroid medications, preferably started before amiodarone to suppress new hormone synthesis, may help control thyrotoxicosis symptoms in the short term. However, data remain limited due to the absence of randomized controlled trials and their known thyrotoxic properties, for which further investigation is warranted. Presentation: Sunday, July 13, 2025