Left main coronary artery compression syndrome with an incomplete atrioventricular septal defect presenting as angina induced by hyperthyroidism.

We herein report the case of a 29-year-old woman who was diagnosed with incomplete atrioventricular septal defect and extrinsic compression of the left main coronary artery (LMCA) with chest pain due to postpartum thyroiditis. She exhibited chest pain with ST elevation, and coronary computed tomography showed that the LMCA was compressed between the dilated pulmonary artery and aorta. After her hyperthyroidism was treated, her chest pain resolved. Surgical repair of endocardiosis and coronary bypass grafting were performed. On the one-year follow-up visit, the dilation of the pulmonary artery and right heart was decreased. It is important to consider the possibility of compression of the LMCA in patients presenting with pulmonary hypertension and chest pain.