Left main coronary artery spasm in a hyperthyroid patient with suspected acute coronary syndrome

The left main coronary artery (LMCA) vasospasm is rare. We report a suspected acute coronary syndrome patient with hyperthyroidism who had LMCA vasospasm. Coronary angiogram showed 60% stenosis at LMCA. After administering nitroglycerin, re-angiography showed no significant stenosis. Then we evaluated LMCA lesion using intravascular ultrasound (IVUS) showing no significant stenosis. We considered that it was a LMCA vasospasm and may be assosiated with hyperthyroid state. After anti-thyroid and anti-spasm treatment, chest pain subsided. In conclusion, hyperthyroidism induced coronary hypersensitivity may contribute to LMCA vasospasm as seen in this case. IVUS may be useful to identify coronary vasospasm.