The unligated left internal mammary artery side branch as the cause of angina after coronary artery bypass grafting.

The left internal mammary artery (LIMA) is a widely used conduit during coronary artery bypass graft (CABG) surgery because of its excellent long-term patency. Although large LIMA side branches are typically ligated during the surgery, the occurrence of a coronary steal phenomenon related to these side branches following surgery remains controversial. Advocates for occlusion of LIMA side branches in the setting of left anterior descending artery (LAD) ischemia indicate that anginal symptoms often improve and that objective measures of LAD ischemia frequently resolve. We present a patient with ischemia in the LAD distribution secondary to coronary steal from a large LIMA side branch that was successfully treated using the Embolization Coil-IMWCE-3-PDA5 (Cook Medical, Bjaeverskov, Denmark).