Abstract 10988: The Dynamic Duo of Electrical and Thyroid Storm Caused by Amiodarone

Abstract

Case description: A 61 year-old male with a hx of CAD s/p CABG and HFrEF s/p AICD presents with a 4-day history of dizziness and shortness of breath; he was found to be in ventricular tachycardia (VT) storm. ICD interrogation was found to have 13 shocks in 24 hours. His thyroid function tests (TFT) were abnormal: TSH undetectable, elevated FT4 7.7 (0.93-1.7) and T3 246.6 (84-202) ng/dL, respectively. He was diagnosed with severe thyrotoxicosis, likely due to amiodarone-induced thyrotoxicosis (AIT) type 2 and a Burch-Wartofsky score of 50, highly suggestive of thyroid storm (TS). He was started on hydrocortisone, prednisone, propylthiouracil, and metoprolol for the TS. Procainamide drip had been initiated for VT and titrated until VT was controlled. Repeat TFTs in 48 hours showed no changes in TSH or FT4, but T3 had normalized. Procainamide and hydrocortisone were discontinued after VT frequency had decreased. Discussion: An electrical storm (ES) is a state of electrical instability characterized by multiple episodes of VT in 24 hours. In patients with ICD, it is defined as >3 anti-tachycardic pacing therapies or shock. Most patient with ES have severe underlying structural heart disease with various inciting events such as thyrotoxicosis. Amiodarone is the drug of choice in VT; however, complications such as AIT should be recognized. Thyroid hormone has a direct arrhythmogenic effect on the heart through various cellular mechanisms. In our patient, amiodarone was discontinued after the diagnosis of AIT. Procainamide and antithyroid therapy were started, which subsequently controlled the VT. Resistance to therapy can occur, and more elaborate interventions such as plasmapheresis are an option to remove amiodarone, its metabolites, and free thyroid hormones. Conclusion: Amiodarone is the most efficacious medication for VT. However, it is important to recognize possible life-threatening complications of this medication, such as AIT, which itself can exacerbate VT.