Case in Point The Importance of Subclavian Angiography in the Evaluation of Chest Pain : Coronary-Subclavian Steal Syndrome

C oronary-subclavian steal syndrome (CSSS) is a rare clinical entity with an incidence of 0.2% to 0.7%. Despite its scarcity, CSSS is a condition that can result in devastating clinical consequences, such as myocardial ischemia, ranging from angina to myocardial infarction (MI) and ischemic cardiomyopathy. In 1974, Harjola and Valle first reported the angiographic and physiologic descriptions of CSSS in an asymptomatic patient who was found to have flow reversal in the left internal mammary artery (LIMA) graft in a follow-up coronary angiography performed 11 months after coronary artery bypass grafting (CABG). Because of the similarity in the pathophysiology of this condition with vertebral-subclavian steal syndrome, this clinical entity was named coronary-subclavian steal syndrome (CSSS). In steal-syndrome phenomena, there is a significant stenosis in the subclavian artery proximal to the origin of an arterial branch, either LIMA or vertebral artery, resulting in lower pressure in the distal subclavian artery. As a result, the negative pressure gradient might be sufficient to cause retrograde flow; consequently causing arterial branch “flow reversal,” and then “steal” flow from the organ—either heart or brain—supplied by that artery. Coronary-subclavian steal syndrome is caused by a reversal of flow in a previously constructed internal mammary artery (IMA)-coronary conduit graft. It typically results from hemodynamically significant subclavian artery stenosis proximal to the ipsilateral IMA. The reversal of flow will “steal” the blood from the coronary territory supplied by the IMA conduit. The absence of proximal subclavian artery stenosis does not preclude the presence of this syndrome; reversal in the IMA conduit can occur in association with upper extremity hemodialysis fistulae or anomalous connection of the left subclavian artery to the pulmonary artery in d-transposition of the great arteries. Although the stenosis is most commonly caused by atherosclerotic disease, other clinical entities, including Takayasu vasculitis, radiation, and giant cell arteritis, have been described. Patients with CSSS usually present with stable or unstable angina as well as arm claudication and various neurologic symptoms. The consequence of CSSS can include ischemic cardiomyopathy, acute MI, stroke, and death.