Thyrotoxicosis-Induced Myopericarditis as the Initial Presentation of Graves' Disease.

Thyrotoxicosis-induced myopericarditis is an uncommon but increasingly recognized cardiovascular manifestation of Graves' disease that may closely mimic acute coronary syndrome (ACS). We present a 42-year-old woman with obesity and tobacco use who presented with severe chest pain, ST-segment elevations, and elevated troponins concerning for acute coronary syndrome. Coronary angiography demonstrated non-obstructive coronary arteries, while further evaluation revealed severe thyrotoxicosis with impending thyroid storm and inflammatory findings consistent with myopericarditis. The patient was treated with anti-inflammatory therapy, antithyroid medications, beta-blockers, and corticosteroids with significant clinical improvement. This case highlights the importance of considering thyrotoxicosis-associated myopericarditis in patients presenting with myocardial injury and non-obstructive coronary arteries.