BACKGROUND: Coronary subclavian steal syndrome (CSSS) is defined as retrograde flow in the internal mammary artery graft, after coronary artery bypass surgery, resulting in anterior wall myocardial ischemia. If undiagnosed, it may lead to significant infarction. Its incidence has been under-reported.

CASE REPORT: A 74-year-old woman presented with sudden onset of typical angina, which was associated with dyspnea, nausea, and vomiting. Her medical history was significant for coronary artery disease, with prior coronary artery bypass surgery (CABG), chronic obstructive pulmonary disease (COPD), hypertension, diabetes type 2, dyslipidemia, hypothyroidism, and depression. Physical examination demonstrated a weak left radial pulse, and a differential blood pressure reading in her arms. She developed massive hematochezia that resulted in electrocardiogram changes: ST segment depression in the inferior and lateral leads with isolated ST segment elevation of aVR. Cardiac catheterization demonstrated retrograde flow through the left internal mammary artery (LIMA), resulting in CSSS.

CONCLUSIONS: This case highlights the diagnostic challenge of CSSS as the underlying etiology for ischemia in a patient with remote coronary artery bypass surgery (CABG). It underscores the importance of thorough physical examination in patients who are at high risk for coronary atherosclerosis and remote complications after CABG. It also highlights optimal strategies for management of CSSS with percutaneous transluminal angioplasty.

Keywords: Angina, Stable - etiology, Coronary Artery Bypass, Coronary-Subclavian Steal Syndrome - diagnosis, Gastrointestinal Hemorrhage - etiology