Endocrine Abstracts

Introduction: Amiodarone-induced thyrotoxicosis (AIT) in patients with congenital heart disease (CHD) has an estimated cumulative incidence of 13–21%, and prompt reversal to euthyroidism is crucial in these patients. We present a case of refractory AIT in a patient with CHD who was treated with thyroid arterial embolization (TAE).

Clinical case: A 34-year-old male with complex cyanotic CHD (great vessels transposition, interventricular communication), had palliative cardiac surgery in his childhood and developed heart failure (HF), pulmonary hypertension, and supraventricular tachyarrhythmias. Since 2013 he was treated with amiodarone with no adverse effects. In April 2019 he was referred to our Endocrinology Department due to thyrotoxicosis, which was detected due to worsening of HF and weight loss, irritability and tremor of the extremities with 4 months of evolution. He had TSH 0.02 uIU/ml [0.35–4.94] FT4 2.12 ng/dl [0.70–1.48] FT3 5.86 pg/ml [1.88–3.18]. Analytical reassessment at 1st visit: TSH < 0.01 mIU/l FT4 4.60 ng/dl FT3 14.57 pg/ml, TRAB negative. He started therapy with thiamazole 30 mg/day and prednisolone 40 mg/day. Despite a favorable initial response, the clinical and analytical condition deteriorated – ventricular tachyarrhythmia with implantable cardioverter-defibrillator placement – requiring multiple admissions, increasing doses of thiamazole (60 mg/day) and glucocorticoids (dexamethasone 10 mg/day) and initiation of cholestyramine 24 g/day and lithium 800 mg/day. On the 4th month of follow-up, due to failure of medical therapy, thyroidectomy after plasmapheresis was considered, but both were contraindicated by the patient’s cardiac condition. After multidisciplinary team discussion, it was decided to perform TAE of the 4 arteries with polyvinylalcohol particles 250–300 microns, using hybrid imaging with angiography and computed tomography. There were no complications and gradual clinical and analytical improvement was obtained. On the 14th week after the procedure, the patient reached normal thyroid function on lower doses of anti-thyroid drug and no need of glucocorticoid.

Conclusion: This case was challenging, not only because it was urgent to control thyroid function due to cardiac deterioration, but also because thyroidectomy was contraindicated and AIT was refractory to medical treatment. TAE is rarely employed in AIT, but has proved to be the only therapeutic option in this patient, solely possible in a center with experienced interventional radiology unit.