Right internal mammary artery steal syndrome: successful percutaneous coil embolization of a collateral branch-case report.

BACKGROUND: Coronary artery bypass grafting (CABG) is a common revascularization strategy, yet ischaemic symptoms may persist despite patent grafts. CASE SUMMARY: We describe a 60-year-old man with three-vessel coronary artery disease treated with triple CABG who presented with persistent dyspnoea and inferolateral myocardial hypoperfusion. Repeat coronary angiography demonstrated patent grafts but identified a collateral branch of the right internal mammary artery causing a steal phenomenon. Coil embolization of the collateral vessel led to complete symptom resolution and normalization of myocardial perfusion. DISCUSSION: This case highlights a rare cause of CABG steal syndrome and emphasizes the need for careful assessment of internal mammary artery branches in patients with ongoing post-CABG ischaemia.