Endocrine Abstracts

Case history: A 64 year old male attended the Emergency Department with palpitations on 02/11/2023. He had previous extensive cardiovascular disease: Ventricular Tachycardia (VT) - ICD (2021) and 2 ablations (2022, 2023); Myocardial Infarctions (2005, 2021); and moderate Left Ventricular Systolic Dysfunction (LVSD). He was treated with amiodarone from July 2021 which was stopped after his second ablation in August 2023. Interrogation of his pacemaker showed new atrial fibrillation with rapid ventricular response (fAF); 2 shocks had fired due to VT. He was admitted for rate control with monitoring. Thyroid Function Tests (TFTs) showed a new severe thyrotoxicosis (TRAB negative). Amiodarone-Induced-Thyrotoxicosis was the suspected aetiology. He was commenced on carbimazole and prednisolone, with digoxin and bisoprolol for rate control. He continued to have runs of VT with refractory fAF, and developed signs of cardiac decompensation. Ten days after admission, he was transferred to the tertiary hospital cardiac unit.

Results and treatment: He had input from multiple specialties: endocrinology, cardiology, general surgery, haematology and anesthetists. Emergency total thyroidectomy would take weeks to schedule. He was on an ATD cocktail of Propylthiouracil, IV hydrocortisone, lithium, cholestyramine, and propanolol MR, but now also required Plasma Exchange therapy (PLEX). This did cause thyroid improvement, but with temporary effect, and also caused hypocalcaemia. To achieve cardiac stability, his treatment was escalated to IV lidocaine. The prolonged course raised toxicity concerns, but cessation caused VT. He had to be weaned onto oral mexiletine as an alternative until surgery. Still mildly thyrotoxic, he had a total thyroidectomy on 30/11/23 with minimal complications. Post-surgery, all ATDs were stopped and was in sinus rhythm on 4 medications – including amiodarone. He required multiple specialty outpatient follow-up, which included thyroid and calcium replacement.

Conclusions and points for discussion: Patients with AIT and LVSD are at a higher risk of morbidity and mortality. This case demonstrates the complexity of multi-specialty input required to manage intricate life-threatening conditions. In particular it shows the value of thyroidectomy as a rapid euthyroid strategy, but highlights the reality in co-ordinating logistical aspects, especially with considering therapeutic toxicities and responses to therapy.