Document Type

Conference Proceeding

Publication Date

5-2-2025

Abstract

Coronary Subclavian Steal Syndrome (CSSS) is a rare but serious complication of coronary artery bypass grafting (CABG). It occurs when the left anterior descending (LAD) coronary artery is bypassed from the left subclavian artery (LSA) using the left internal mammary artery (LIMA). The syndrome arises due to stenosis of the LSA, leading to reduced blood flow through the LIMA. This triggers retrograde flow from the LIMA to the distal LSA, resulting in myocardial ischemia despite patent grafts. Clinical presentation can vary from asymptomatic cases to severe manifestations such as new-onset heart failure or acute coronary syndrome (ACS). A 79-year-old female with history significant for ACS status post CABG (LIMA-LAD) and breast cancer status post radiation presented with chest pain. She described it as dull pain in her substernum that woke her up from her sleep and felt similar to her prior ACS episode. Initial evaluation, including EKG, troponins, and chest X-ray, was unremarkable. However, echocardiography revealed regional wall motion abnormalities. Subsequent left-heart catheterization demonstrated a patent LIMA-LAD graft. However, it revealed 80% proximal stenosis of the LSA with a translesional pressure gradient that increased from 20 to 40 mmHg after nitroglycerin, confirming retrograde flow consistent with CSSS. A stent was successfully placed in the LSA, leading to symptom resolution. The patient was discharged on dual-antiplatelet therapy for 6 months. It is estimated that up to 12% of patients undergoing CABG have LSA stenosis, although only a small subset develop CSSS. The most significant risk factor for CSSS is concurrent peripheral artery disease. Notably, the AHA guidelines do not currently recommend routine screening for LSA stenosis as part of the pre-CABG evaluation. However, studies have shown that a bilateral systolic blood pressure difference exceeding 15 mmHg has a specificity of 99% for identifying LSA stenosis. Most cases of LSA stenosis are attributed to atherosclerosis, which likely played a significant role in this patient’s condition. However, her history of breast cancer treated with radiation could also have contributed to the LSA stenosis, representing a unique cause of CSSS. Regardless of the underlying etiology, CSSS should remain a key consideration in the differential diagnosis for post-CABG patients presenting with angina

Comments

American College of Physicians Michigan Chapter and Society of Hospital Medicine Michigan Chapter 2025 Resident and Medical Student Day, May 2, 2025, Troy, MI

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