Case Files by Dr. George

Recurrent Angina 12 Years After Coronary Bypass Surgery

Hesam Mostafavi Toroghi, MD, Department of Medicine, Yaser Alhamshari, MD, Chitra Punjabi, MD, Jon C. George, MD, Department of Cardiovascular Diseases, Einstein Medical Center, Philadelphia, Pennsylvania

Hesam Mostafavi Toroghi, MD, Department of Medicine, Yaser Alhamshari, MD, Chitra Punjabi, MD, Jon C. George, MD, Department of Cardiovascular Diseases, Einstein Medical Center, Philadelphia, Pennsylvania

Abstract

Subclavian steal syndrome is a wellknown phenomenon where a stenosed subclavian artery leads to neurologic symptoms due to retrograde flow in the vertebral artery. The lesser known coronary subclavian steal syndrome (CSSS) is an under-diagnosed condition affecting coronary artery bypass grafting (CABG) patients who subsequently develop concurrent subclavian artery stenosis, which reverses the blood flow from the left anterior descending artery to the left internal mammary artery, resulting in myocardial ischemia. We report the case of a 68-year-old male with a history of CABG 12 years prior who presented with recurrent angina. Discrepant blood pressure measurements in his upper arms prompted a computed tomography (CT) angiography of the chest, abdomen, and pelvis to rule out dissection. CT showed only a possible proximal left subclavian stenosis. Findings supportive of CSSS on percutaneous angiography led to stenting of the subclavian artery, which in turn, resulted in resolution of the patient’s symptoms. CSSS should be suspected in patients who present with uncontrolled angina post CABG, especially when physical exam shows differential blood pressure measurements in the upper extremities.

Coronary subclavian steal syndrome (CSSS) is defined as myocardial ischemia caused by reversal of blood flow in the internal mammary artery as a result of proximal stenosis in the subclavian artery. It is an uncommon condition after a coronary bypass graft operation. However, studies have shown increasing incidence.1,2 Here we present a patient with CSSS presenting with persistent angina 12 years post coronary artery bypass grafting (CABG). 
 
Case Presentation
 
A 68-year-old gentleman presented to the emergency room with recurrent, substernal, exertional chest pain that was relieved with rest. His past medical history was significant for hypertension, diabetes, and coronary artery disease (CAD), for which he had undergone CABG with left internal mammary artery (LIMA) to left anterior descending artery (LAD) grafting and LAD stenting 12 years prior. He also had ischemic cardiomyopathy, bilateral renal artery stenosis, and peripheral arterial disease. Notably, on physical exam, there was discrepancy in blood pressure readings of his upper extremities, with 140/80 mmHg on the right, and 80/50 mmHg on the left. Electrocardiogram showed nonspecific ST-segment changes unchanged from prior and cardiac troponin was undetectable. Echocardiogram showed a mildly reduced ejection fraction of 45%, along with mild diastolic dysfunction and mild right ventricle systolic dysfunction. No new wall motion abnormality was seen. Given the blood pressure discrepancy, aortic dissection was considered and a computed tomography angiogram (CTA) of the chest, abdomen and pelvis was obtained. CTA ruled out dissection, but was suggestive of possible proximal left subclavian artery stenosis, a finding that raised the suspicion for CSSS as a cause of the patient’s recurrent angina. The patient underwent coronary and subclavian percutaneous angiography, which revealed patent LAD stents. There was 80% stenosis in the left subclavian artery proximal to the LIMA graft, with a 40 mmHg pressure gradient across the lesion. Retrograde and competitive flow was noted in both the distal LAD and vertebral arteries, confirming CSSS (Figure 1). Subsequent left subclavian lesion dilation and stenting was performed, resulting in brisk flow and resolution of patient’s symptoms (Figure 2).
 
Discussion
 
Subclavian artery stenosis has a prevalence of about 2% in general population and 7% in the population at high risk for peripheral arterial disease. It is correlated with smoking, higher systolic blood pressure, and lower HDL levels.3,4 Approximately 0.2 to 6.8% of the cases with left subclavian artery stenosis that undergo CABG with LIMA-to-LAD graft will be complicated by CSSS.
 
CSSS is a steal phenomenon where blood flows in retrograde fashion from the coronary arteries into the LIMA. For this to occur, there must be hemodynamically significant stenosis of the subclavian artery that compromises delivery to the upper extremities. When oxygen demand in the upper extremity is increased, blood is “stolen” from the coronary arteries, leading to myocardial ischemia. CSSS was first described in 1974 and is considered to be an uncommon condition. However, the incidence is rising as the number of LIMA-to-LAD grafts and life expectancy increase.5
 
CSSS can have a wide variety of manifestations, the most common being recurrent angina, as seen in our patient. It can also present as acute coronary syndrome, ischemic cardiomyopathy, and ventricular arrhythmias.6,7
 
While stenosis secondary to atherosclerosis is the most common cause, other rare causes have been also reported, including Takayasu’s and giant cell arteritis, external compression, or radiation arteritis.8,9 Cases of CSSS from LIMA by the ipsilateral arterio-venous dialysis fistula have also been reported, even without significant stenosis.10
 
CSSS should be suspected in patients who have undergone CABG presenting with uncontrolled angina and when physical exam shows differential blood pressure measurements in the upper extremities of greater than 15 mmHg. The main risk factors for subclavian artery stenosis, including hypertension, diabetes, smoking, and peripheral arterial disease, were all present in our patient.   
 
Given the relatively high prevalence of subclavian artery stenosis especially in patients with CAD risk factors, and its asymptomatic nature, thorough pre-operative evaluation is necessary before CABG. Bilateral brachial blood pressure should be measured to diagnose any possible stenosis, although it can miss patients with equal stenosis in bilateral subclavians.1,3 Some studies have shown benefit from echocardiographic screening of the subclavian artery stenosis before CABG.11 Different modalities can be used to diagnose CSSS, including CTA, MRA, and Doppler ultrasound. However, coronary angiography remains the gold standard, because it offers the ability to see dynamic, competitive, retrograde blood flow.5,12 
 
There is no definitive medical therapy for CSSS. However, treatments for reducing atherosclerotic risks, including aspirin and a high-intensity statin, should be implemented. Anti-anginal medications such as beta-blockers, calcium channel blockers, and nitrates can be used for symptomatic treatment as a temporizing measure. Definitive treatment options include percutaneous balloon angioplasty, balloon angioplasty and stenting, and surgical endarterectomy or bypass. Revascularization is generally reserved for symptomatic patients experiencing angina, acute coronary syndrome, decompensated heart failure, ventricular arrhythmia, or vertebral subclavian steal symptoms such as dizziness, syncope, stroke, etc. A recent study showed that subclavian stenting in asymptomatic patients with subclavian artery stenosis before LIMA-to-LAD CABG is safe and effective with low complications.13,14 More data are needed to compare different treatment approaches in the setting of potential CSSS. 
 
References
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  8. Cardon A, Leclercq C, Brenugat S, et al. Coronary subclavian steal syndrome after left internal mammary bypass in a patient with Takayasu’s disease. J Cardiovasc Surg (Torino). 2002 Aug; 43(4): 471-473.
  9. Elian D, Gerniak A, Guetta V, et al. Subclavian coronary steal syndrome: an obligatory common fate between subclavian artery, internal mammary graft and coronary circulation. Cardiology. 2002;97(4):175-179.
  10. Horn B, Kanjanahattakij N, Parasuram K, et al. Coronary steal from a left internal mammary artery bypass graft via high output hemodialysis arteriovenous fistula. Cath Lab Digest. 2017; 25(8): 1-5.
  11. Saleem D, Majdi H. Echocardiographic diagnosis of left subclavian artery stenosis before coronary artery bypass grafting (CABG). Int J Cardiol. 2016; 203: 30-31. doi:10.1016/j.ijcard.2015.10.034.
  12. Toprak C, Yesin M, Mustafa Tabakci M, et al. Coronary subclavian steal syndrome evaluated with multimodality imaging. Intern Med. 2015; 54(21): 2717-2720. doi:10.2169/internalmedicine.54.4979.
  13. Che WQ, Dong H, Jiang XJ, et al. Stenting for left subclavian artery stenosis in patients scheduled for left internal mammary artery-coronary artery bypass grafting. Catheter Cardiovasc Interv. 2016 Mar; 87 Suppl 1: 579-88. doi: 10.1002/ccd.26477.
  14. Fonseka N, Dunn J, Andrikopoulou E, Finkel J. Coronary subclavian steal syndrome. Am J Med. 2014 Aug;127(8):e11-2. doi: 10.1016/j.amjmed.2014.03.006.

Disclosure: The authors report no conflicts of interest regarding the content herein.

The authors can be contacted via Hesam Mostafavi Toroghi, MD, at mostafas@einstein.edu.