FRI506 Severe Dilated Cardiomyopathy As First Manifestation Of Thyrotoxicosis- A Case Report

Disclosure: Z. Saeed: None. C. Labib: None. W. Althunibat: None. M. Varatharajah: None. Introduction: Hyperthyroidism is a common metabolic disorder with prominent cardiovascular manifestations ranging from palpitations, angina-like chest pain, exercise intolerance and dyspnea to high-output heart failure and dilated cardiomyopathy. Approximately 6% of patients with hyperthyroidism/thyrotoxicosis develop symptoms of heart failure and less than 1% develop dilated cardiomyopathy with reduced left ventricular systolic function. Here we present a case of a 55-year-old man who presented with symptoms of heart failure and was diagnosed with dilated cardiomyopathy due to thyrotoxicosis. CASE PRESENTATION: 55-year-old man with a past medical history of vitiligo and cirrhosis presented to the emergency department with complaint of lower extremity swelling, cough, dyspnea on exertion, chest discomfort, palpitations and lethargy for two weeks. He also had a weight gain of 14 lbs. in this period. In the emergency department he had a heart rate of 118 beats/minute, physical exam revealed bilateral fine hand tremors, bibasilar crackles and a 2/6 holosystolic murmur on chest auscultation as well as hyperactive deep tendon reflexes. EKG showed atrial fibrillation with a rate of 184 beats/min. Initial chest imaging showed cardiomegaly, perihilar congestive changes and small right pleural effusion. CT abdomen & pelvis demonstrated moderate volume ascites. Lab work showed a TSH of 0.00 mIU/L (0.5-5.0. mIU/L), T4 Free 5.3 ng/dL (0.9-2.3 ng/dL), Troponin T 36 ng/L, pro BNP 3150 pg/ml. He was given furosemide, propranolol, hydrocortisone, a bolus of diltiazem and was started on diltiazem and heparin drip and admitted to the hospital. Endocrinology was consulted and he was started on methimazole and methylprednisolone. Transthoracic echocardiogram showed an ejection fraction of 15%. Thyroid ultrasound was negative for any nodules or mass. Cardiac catheterization was done which revealed moderate pulmonary hypertension, non-ischemic dilated cardiomyopathy. Patient was discharged home on methimazole and guideline directed medical therapy for heart failure. He followed outpatient with Endocrinology and Cardiology. Six months after his hospital admission, repeat TSH was 1.71 mIU/L after treatment. Repeat echocardiography showed an improvement in ejection fraction from 15% to 35-40%. DISCUSSION: Prolonged untreated hyperthyroidism leads to high output heart failure characterized by an increase in heart rate, cardiac contractility and cardiac output which in some cases progresses to dilated cardiomyopathy with impaired left ventricular systolic function. Heart failure with reduced ejection fraction is a frequently encountered problem, most commonly due to ischemic cardiomyopathy. Thyrotoxicosis is one of the rare and reversible causes of nonischemic dilated cardiomyopathy which must be promptly diagnosed and treated in order to prevent life threatening complications. Presentation: Friday, June 16, 2023