Pharmacological Management of Amiodarone-Induced Thyrotoxicosis Type I in Mitral Valve Replacement Joanne Lau, BScPhm; Rita Dhami, BScPhm Amiodarone-induced thyrotoxicosis (AIT) delays urgent cardiac surgeries Patients are at risk of thyroid storm if exposed to anesthesia and surgery while hyperthyroid Options for converting AIT patients to euthyroidism: Thyroidectomy: rapidly achieves euthyroidism (demonstrated in multiple case reports) Medical management: may require months of treatment In this case thyroidectomy was not possible. Only one other case report describes an AIT Type II patient undergoing urgent surgery without conversion to euthyroidism. ID 53 year old female Past Medical History Atrial fibrillation (x3 years) Mitral valve stenosis/regurgitation Lupus Hypertension Hyperlipidemia History of ovarian cancer (hysterectomy 2 years ago) Medications Amiodarone 200 mg x 3.5 years Carbamazepine 300 mg AM and 200 mg PM Hydroxychloroquine 200 mg BID Lansoprazole 30 mg daily Atorvastatin 20 mg daily Candesartan 4 mg daily Calcium 500 mg (elemental) daily Alendronate 70 mg QMonday Warfarin 1 mg daily Rationale Patient presented to hospital with signs and symptoms of hyperthyroidism and was diagnosed with AIT Type I: TSH<0.01 mU/L [0.4-5 mU/L] T3=16.7 pmol/L [3-6.5 pmol/L] T4=84 pmol/L [11-22 pmol/L] Shortness of breath, tachypnea, fine tremor, and weight loss (10 lbs over 2 weeks) She required mitral valve replacement (MVR) for severe mitral valve stenosis and regurgitation Case Description Discussion Treatment for AIT: For our case: Resolution of hyperthyroid symptoms occurred with initiation of propylthiouracil therapy Treatment success of propylthiouracil over methimazole may be due to its mechanism of inhibiting T4 and conversion to active T3 Evaluation of Literature: One case report of necessary surgery (excluding thyroidectomies to treat AIT) in unresolved AIT Type II: Propylthiouracil, prednisone, and propranolol achieved symptom control, but patient remained hyperthyroid Despite this, percutaneous tracheotomy was performed  recurrent thyrotoxicosis unresponsive to treatment and patient died 7 days later The authors recommend thyroidectomy be performed with percutaenous tracheotomy in this setting. Conclusions Patients with AIT can be rapidly converted to euthyroidism by thyroidectomy. Where urgent surgery is required and thyroidectomy is not possible, this case demonstrates the plausibility of pharmacological resolution of hyperthyroid symptoms and suppression of thyroid storm peri- and post-operatively. AIT Type I AIT Type II Thyroid hormone overproduction Thyroid hormone release via destructive thyroiditis Propylthiouracil 150-200 mg TID Or Methimazole 15-20 mg BID Prednisone 40-60 mg daily References Amiodarone was discontinued (sotalol 20 mg BID started for rhythm control) If mechanism is unclear, use a combination of thionamide and steroid therapy Noble K. Thyroid Storm. Patho Corner. Journal of PeriAnesthesia Nursing. 2006 April;21(2):119-125. Conen D, Melly L, Kaufmann C, Bilz S, Ammann P, Schaer B, Sticherling C, Muller B, Osswald S. Amiodarone-Induced Thyrotoxicosis: Clinical Predictors and Outcomes. J Am Coll Cardiol. 2007 Jun 19;49(24):2350-5. Papaioannou V, Terzi I, Dragoumanis C, Konstantonis D, Theodorou V, Pneumatikos I. A fatal case of recurrent amiodarone-induced thyrotoxicosis after percutaneous tracheotomy: a case report. Journal of Medical Case Reports. 2007 Nov 13;1:134. Tsang W, Houlden RL. Amiodarone-induced thyrotoxicosis: A review. Can J Cardiol 2009;25(7):421-424. Methimazole was started No clinical effect seen after 4 weeks Subsequently discontinued If poor response consider thyroidectomy Patient Information Propylthiouracil 100 mg TID started Symptomatic control within 1 week MVR urgently needed (Rapid conversion to euthyroidism by thyroidectomy not possible as anticoagulation will be necessary for MVR) Pre-surgery medical management (3 weeks): Propylthiouracil 200 mg TID Dexamethasone 2 mg BID Propranolol 80 mg TID (patient unable to tolerate sotalol) Pace maker rate controlled Symptom free but still hyperthyroid: TSH <0.01 mU/L [0.4-5 mU/L] T3=10.1 pmol/L [3-6.5 pmol/L] T4=47 pmol/L [11-22 pmol/L] Post-MVR: signs and symptoms of thyroid storm absent Patient successfully discharged