Case Presentation: A 75-year-old man with coronary artery disease and triple vessel coronary artery bypass graft surgery with a LIMA-LAD, saphenous vein graft to obtuse marginal and right coronary artery (SVG-OM and SVG-RCA) fifteen years prior presented to his local Veterans Affairs hospital with dizziness and recurrent falls. His medical history included atrial fibrillation, diabetes, hypertension, and hyperlipidemia. Inpatient testing for his recurrent falls revealed a blood pressure differential between the left and right arm that worsened with left arm exertion. A CT angiogram of the chest was performed, which demonstrated severe stenosis at the ostium of the left subclavian artery proximal to the origin of the LIMA. A coronary angiogram and subclavian artery catheterization was subsequently performed and revealed significant proximal subclavian artery stenosis with >50 mmHg gradient between the left subclavian artery and the aorta; retrograde flow was visualized through the patent LIMA-LAD graft. In addition to ‘steal’ coronary blood flow, his dizziness and associated falls were attributed to ‘steal’ of vertebral blood flow. The subclavian artery stenosis was not amenable to percutaneous stenting, as it was deemed too close to the origin of the ipsilateral vertebral artery and high risk for vertebral artery obstruction. The patient was evaluated by vascular surgery and underwent carotid-subclavian bypass.
Discussion: The prevalence of Coronary Subclavian Steal Syndrome (CSSS) is increasing as more patients receive CABG along with greater life expectancy after CABG. CSSS affects 0.2–6.8% of CABG patients with a patent LIMA-LAD graft [1]. The mean duration between CABG and the development of symptoms of CSSS is about 9.0 ± 8.4 years [2]. CSS can present without symptoms; a difference in systolic blood pressure > 15 mm Hg between arms could be the only external manifestation. A high degree of suspicion is warranted and bilateral brachial blood pressures during routine annual visits after CABG can be used to screen for the interval development of subclavian artery stenosis. Classically, exertion of the left arm causes anginal symptoms and, in extreme cases, myocardial infarction. The European Society of Cardiology 2011 guidelines recommend consideration of endovascular intervention before surgery for the management of symptomatic CSSS (Recommendation Class I, Level of Evidence C) [3].
Conclusions: CSSS is a manifestation of subclavian artery stenosis rarely found in patients who have undergone coronary artery bypass grafting (CABG). CSSS occurs when a patient with a patent left internal mammary artery bypass graft anastomosed to left anterior descending artery (LIMA-LAD) develops a significant (>75%) proximal subclavian artery stenosis. In this context, blood flows retrograde through the patent LIMA-LAD graft to supply the subclavian artery distal to the stenosis.