Myocardial infarction in Graves' disease without coronary artery disease.

A 45-year-old female without coronary risk factors showed a 20 kg decrease in body weight, hyperhydrosis, palpitations and dyspnea on exertion for 2 months, and nocturnal dyspnea for 1 month before admission. She did not notice chest pain indicative myocardial infarction or fever suggestive myocarditis. Graves' disease was confirmed by exophthalmos and elevated titers of T3 and T4 thyroid hormones. Cardiac catheterization studies demonstrated no significant coronary artery disease but showed akinesis of the anteroseptal and apical walls which suggested myocardial infarction. Thyroid hormone may directly influence myocardial oxygen supply and demand and, by some unknown mechanism, cause a critical imbalance in coronary circulation resulting in myocardial infarction.