SAT-462 Coronary Vasospasm-Induced Myocardial Infarction: An Uncommon Presentation of Thyrotoxicosis

Abstract

Background: Coronary artery vasospasm-induced myocardial infarction is a rare cardiac complication of untreated thyrotoxicosis. Diagnosis is difficult due to the transient and unpredictable occurrence of coronary spasm [1]. Clinical Case: A 47-year-old Hispanic female smoker presented with a one-week history of severe, intermittent substernal chest pain radiating to the left arm. The pain was associated with palpitations and shortness of breath. She was afebrile with a heart rate of 100, a blood pressure of 119/59, a fine tremor, and brisk reflexes. No lid lag or proptosis was appreciated. The thyroid was enlarged, non-tender, without palpable nodules. ECG showed T- Wave Inversions in leads V1-V2 and ST depressions in V4-V5. Chest pain was relieved by SL nitroglycerin.Lab results showed a peak Troponin of 0.20 (N < 0.06), TSH 0.01 mU/L (N > 0.45mU/L), free T4 5.54 (N < 1.46 ng/dl), total T3 4.50 pg/mL (N < 1.37 ng/mL), free T3 21.0 ng/mL (N < 4.4 pg/ml), TSI 3.61 IU/L (N < 0.55 IU/L), thyrotropin R Ab 7.47 IU/L (N < 1.75 IU/L) and thyroglobulin Ab 1.3 IU/ml (ULN < 0.9 IU/ml). Thyroid US showed a heterogeneous enlarged thyroid gland with increased vascularity.For her NSTEMI she was treated with a heparin drip, aspirin, clopidogrel, atorvastatin, propranolol, and isosorbide mononitrate. Methimazole was started to treat thyrotoxicosis. Cardiac catheterization revealed coronary vasospasm without evidence of valvular or coronary artery disease. Methimazole restored euthyroidism and she has not had recurrence of angina. Discussion: Rarely, hyperthyroidism can present with transient myocardial ischemia secondary to coronary artery vasospasm in patients with normal coronary arteries. The etiopathogenesis is unclear and may relate to a direct metabolic effect of excess thyroid hormone on the myocardium. In a Korean study evaluating chest pain in patients who underwent coronary angiography, the incidence of coronary vasospasm was 5%, occurring most frequently in women under 50 years of age with thyrotoxicosis [2]. Conclusion: Patients who present with angina and are thyrotoxic should be evaluated for vasospasm. Females under 50 years old with Graves’ disease are at highest risk. Treatment includes antithyroid medications along with nitroglycerin, and we can consider calcium channel blockers including diltiazem. Treatment of thyrotoxicosis eliminates recurrence of vasospasm [3].