ST-Segment Elevation Myocardial Infarction Following Left Internal Thoracic Artery-to-Coronary Bypass Secondary to Arterial Steal Phenomenon.

BACKGROUND

In the post-left internal thoracic artery (LITA)-to-coronary artery bypass graft (CABG) setting, anginal symptoms are associated with the presence of large, unligated LITA side branches. These symptoms are mediated by a variable arterial steal phenomenon.

CASE SUMMARY: This report describes an atypical case of ST-segment elevation myocardial infarction (STEMI) following LITA-CABG secondary to a variable arterial steal phenomenon induced by both a branch variant of the LITA and an intercostal artery. Angiography-guided embolization of the branch vessels successfully resolved the patient's ischemia.

DISCUSSION: STEMI secondary to LITA branch-mediated steal has not been previously reported. This case demonstrates that large LITA side branches can lead to myocardial infarction and that embolization of the relevant side branches is an effective treatment strategy.

TAKE-HOME MESSAGES: Providers should be aware that LITA side branches, if not ligated during surgery, may lead to threatening coronary ischemia. If such side branches cannot be ligated intraoperatively, then intravascular embolization is an effective treatment strategy.