SAT-495 Thyrotoxicosis Presenting as Right Sided Heart Failure: Two Case Reports, Two Differing Outcomes Illustrating the Importance of Early Aggressive Treatment to Reverse Cardiac Dysfunction

Background: Graves’ thyrotoxicosis can lead to life-threatening right heart failure requiring urgent treatment. We present two such cases to illustrate management challenges and the importance of early definitive treatment. Clinical cases: The first case is a 41 year old female with Graves’ hyperthyroidism and severe right heart failure. Cardiac ECHO showed LVEF 76% with severe biatrial enlargement, TV regurgitation, and an enlarged RV. The liver was enlarged, transaminases were high, bilirubin was 24 mg/dl (0-1.4), and clotting was prolonged. Due to hepatic dysfunction, methimazole was held. She was not a candidate for I-131 as she had received iodinated contrast. Treatment with dexamethasone and SSKI normalized thyroid function over four days. She was discharged but presented two months later with worsened hyperthyroidism and right heart failure. She was a poor surgical candidate and I-131 was administered as definitive therapy. She developed PEA arrest the following day without recovery leading to withdrawal of care and death eight days later. The second case is also a 41 year old female with an 18 year history of Graves’ disease, intermittently compliant with methimazole. She presented with hyperthyroidism and severe right heart failure. The liver was enlarged, transaminases were high, bilirubin was 5.1 mg/dl, and clotting was prolonged. Cardiac ECHO showed LVEF 66% with severe biatrial enlargement, TV and MV regurgitation, enlarged RV, and increased RA pressure. Due to hepatic dysfunction, methimazole was held. She was not a candidate for I-131 as she had received iodinated contrast. She was prepared for thyroidectomy with aggressive heart failure treatment, dexamethasone, SSKI, and cholestyramine. Thyroid function normalized over six days and she underwent total thyroidectomy eight days after admission without complications. Postoperative cardiac ECHO showed marked improvement of cardiac parameters. Conclusion: Right heart failure is an uncommon and often overlooked complication that can arise in poorly managed or treatment-resistant Graves’ disease. It is life-threatening and requires aggressive normalization of thyroid function, treatment of heart failure, and timely definitive therapy with I-131 or thyroidectomy. Frequently complicated by liver abnormalities, the use of thionamides is questionable. Additionally, hospitalized patients have often been evaluated with iodinated contrast studies or treated with SSKI during the acute phase, which limit the use of I-131. Our cases show that dexamethasone, SSKI, and cholestyramine can rapidly normalize thyroid function. The first case ended in death, probably due to delay in definitive treatment, whereas the second patient had an early thyroidectomy with good outcome. We recommend aggressive treatment to normalize thyroid function and reverse cardiac dysfunction followed by early definitive therapy.