A 50-year-old physician presented to his cardiologist with chest pain. He had a remote history of a redo coronary artery bypass graft (CABG) using the left internal mammary artery (LIMA) a few years ago. On physical examination, his left radial pulse was absent. A carotid duplex examination showed no hemodynamically significant lesions in his internal carotid arteries. The left vertebral flow was noted to be reversed (Figure 16-1). His cardiac catheterization showed a patent LIMA graft. However, he was noted to have a tight preocclusive left subclavian artery stenosis (Figure 16-2). He was referred to our Vascular Surgery Division for a surgical opinion.

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  Coronary subclavian steal syndrome (CSSS) is an uncommon cause of angina and occurs due to decreased coronary blood flow in patients with a patent internal mammary to coronary artery graft.^{1,2,3, and 4}

  
  
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  The usual cause of CSSS is ipsilateral subclavian artery stenosis. The term steal refers to retrograde flow in the vertebral artery secondary to decreased pressure gradient in the mid-to-distal subclavian artery due to occlusion or high-grade stenosis at its origin. The steal can cause cerebrovascular or ipsilateral arm symptoms.

  
  
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  In this patient, the angina was due to either a severe decrease in antegrade flow into the coronary artery or because of an obstructive lesion in the proximal subclavian artery. In some cases retrograde flow from the coronary artery into the arm can also cause angina pectoris.

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  Most patients with uncomplicated subclavian steal syndrome are asymptomatic.

  
  
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  Some patients present with arm claudication on physical exertion and others with vertebrobasilar symptoms due to a relative steal phenomenon occurring from a subclavian stenosis at its origin. This stenosis then results in reversed flow in the ipsilateral vertebral artery causing ischemia of the posterior brain.

  
  
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  The physical examination shows diminished or absent pulses in the ipsilateral arm and a blood pressure differential between the two arms. A bruit may or may not be heard over the clavicle.

  
  
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  In CSSS, the physical findings are similar. Neurologic examination is usually normal.