After non-ST-elevation myocardial infarction, a 61-year-old woman underwent coronary artery bypass grafting with left internal mammary artery (LIMA) to left anterior descending artery combined with saphenous vein grafts to the second obtuse marginal branch and the right coronary artery. At age 79, she was admitted for anterior non-ST-elevation myocardial infarction. Echocardiography showed hypokinesia of the left anterior descending territory. From the left radial approach the LIMA graft was patent, but a critical stenosis of the proximal subclavian artery was diagnosed and treated with stenting. The coronary subclavian steal syndrome usually presents with effort angina but has rarely been reported as a cause of myocardial infarction. A coronary steal syndrome should be suspected in patients with internal mammary artery bypass with recurrence of angina but also in case of acute coronary syndrome. When stable angina is present, a computed tomography scan of the bypass and subclavian artery may allow diagnosis before coronary angiography. In case of urgent coronary angiography and undetectable culprit lesions, selective angiography of the subclavian artery may confirm the suspicion of the coronary steal syndrome.