Internal mammary artery steal syndrome secondary to an anomalous lateral branch.

A 53-year-old male who underwent three-vessel coronary artery bypass grafting had a left internal mammary artery (LIMA) graft to the left anterior descending artery (LAD) and saphenous venous grafts to right coronary artery (RCA) and left circumflex coronary artery. Four years after surgery, he developed exertion angina associated with upper body exercises and even deep breathing at times. Angiographic evaluation revealed an anomalous lateral internal thoracic artery with steal phenomenon documented by adenosine cardiolyte. Patient was successfully treated with transcutaneous steel coil embolization by closing the anomalous vessel. Repeat stress electrocardiogram did not show any signs of ischemia. This case report emphasizes the variability in internal mammary artery (IMA) anatomy and the need to completely ligate all the branches of internal mammary artery intraoperatively.