[en] Radiation-induced heart disease includes various types of cardiac disorders that occur after thoracic irradiation therapy. The coronary artery has been known to be affected in this kind of pathological condition. A 37-year-old man diagnosed with acute coronary syndrome was referred to our institution. He had received irradiation therapy for mediastinal malignant lymphoma at the age of 10 and 11 years. An extended thymectomy for a thymoma via median sternotomy was performed at 18 years old. He also underwent thoracoscopic pericardial fenestration for a pericardial effusion at 26 years old. Coronary angiography revealed severe stenosis of the left and right coronary ostia. Considering the patient's characteristics, including a history of thoracic irradiation therapy, radiation induced heart disease was suspected as a pathogenesis for severe ostial stenosis of the coronary arteries. He underwent conventional on-pump beating coronary artery bypass grafting (CABG) on an urgent basis. Neither internal thoracic artery was suitable for bypass conduit because of dense adhesion. Therefore, the radial artery and great saphenous vein were used as free grafts for coronary revascularization. Furthermore, partial clamping of the ascending aorta seemed to be difficult and inappropriate owing to severe adhesion, so proximal anastomosis devices were used without a side biting clamp. The postoperative course was uneventful and both bypass grafts were patent. Now, he is doing well 10 years after the CABG without any other cardiac event. (author)