SAT-498 Graves’-Associated Takotsubo Cardiomyopathy: An Uncommon Condition

Abstract

Introduction Graves’ disease is an autoimmune disorder that causes excess thyroid hormone (T4 and T3). T4 is converted into T3 (active hormone) in the peripheral tissues by the deiodinase enzyme. T3 has an effect on the cardiac electrical system as well as myocyte contractility. Excess T3 can result in cardiac arrythmias as well as ventricular dysfunction (heart failure). Takotsubo cardiomyopathy is a subtype of nonischemic cardiomyopathy related to severe physiologic or mental stress. Excess catecholamine levels have been reported to cause this disease as well. Takotsubo cardiomyopathy has rarely been reported in Graves’-associated thyrotoxicosis. Case report 55-year-old female who presented to the ED with palpitations and difficulty breathing. She had been seen by her PCP within the past two weeks with complaint of recent 30 lb weight. TSH was noted to be < 0.001 and a neck ultrasound revealed a diffusely enlarged, hypervascular thyroid. She was referred for outpatient endocrinology consultation for further workup. Prior to her initial endocrinology appointment, she developed palpitations and shortness of breath. She did not have any known family history of thyroid disease or other autoimmune conditions. She drinks 1-2 glasses of wine per week and quit smoking in 2017. Physical exam on admission revealed a heart rate of 133 bpm and a blood pressure of 145/93, normal temperature, and normal respirations. Thyroid was diffusely enlarged and without nodularity. No evidence of orbitopathy. Heart was tachycardic but without murmur. Lungs clear. Abdomen soft, nontender. No significant peripheral edema or pretibial rash. No neurological dysfunction. Labs revealed TSH < 0.001, Free T4 > 7.77, Free T3 12.0, TRAb 44.4%, TSI 433%, Anti-TPO 614, high-sensitivity troponin of 112. EKG showed nonspecific infero-lateral T wave changes, rate 123. Echocardiogram demonstrated left ventricular apical hypokinesis but preserved basilar contractility. Ejection fraction was estimated at 40-45%. Nuclear stress test did not reveal any indication of myocardial hypoperfusion. Discussion/Conclusion Takotsubo cardiomyopathy can mimic acute myocardial infarction both clinically as well as on EKG/serum biomarkers. Troponin levels are typically elevated as a result of myocardial stretch and subsequent troponin “leak”. Echocardiogram demonstrates apical ballooning of the left ventricle, and by definition coronary arteries will be free of significant occlusive disease. A small number of cases have been reported in association with endocrine conditions including thyrotoxicosis due to Graves’ disease. The majority of cases associated with thyrotoxicosis will resolve spontaneously with 1-3 weeks. Treatment consists of medication to decrease cardiac preload as well as afterload (ACE inhibitor, beta blocker, diuresis as needed), similar to medical treatment of other nonischemic cardiomyopathies.