Intraoperative diagnosis and successful management of acute coronary-subclavian steal syndrome during off-pump coronary artery bypass grafting: a case report.

Coronary-subclavian steal syndrome (CSSS) is an uncommon but potentially serious complication following coronary artery bypass grafting (CABG). In the presence of significant proximal left subclavian artery stenosis, blood flow within the left internal mammary artery (LIMA) may reverse, leading to myocardial ischemia in the left anterior descending artery (LAD) territory. CSSS typically manifests months to years after CABG, whereas intraoperative onset during the procedure is exceedingly rare and very few cases previously documented. We report a patient who developed acute CSSS during off-pump CABG. Prompt intraoperative diagnosis was achieved using transit-time flow measurement (TTFM), and the condition was successfully managed by immediate LIMA graft reconstruction. This case highlights the critical role of intraoperative flow assessment and timely surgical decision-making in the management of rare but life-threatening complications during CABG.