Left subclavian artery stenosis can be a cause of recurrent angina after coronary artery bypass grafting in patients with a coronary steal. These patients may suffer claudication in the left arm and angina pectoris when using their left arm. The subclavian artery shows retrograde filling with use of a left internal mammary artery graft, which can cause coronary ischemia depending on blood flow. This is a report of a patientwho presented with coronary subclavian steal syndrome and underwent percutaneous implantation of a stent in the left subclavian artery. However, the patient was readmitted with acute coronary syndrome 1 year later. An angiogram showed an unexpected decrease in anterograde flow in the left internal mammary artery graft after stenting the subclavian artery.