I have 4 similar cases in which chest pain persisted at effort and small ischemic area was shown by scintilography. I made closure of the branches using coil embolization with successful angiographic and clinical results.
in my experience it is irrelevant having an open branch in a LIMA graft. blood flow to the coronary arteries goes mainly in diastole and to the systemic branch in systole. i don't think there is a chance for flow steal unless there is a stenotic anastomosis