Background
Carotid artery stenting (CAS) is a minimally invasive technique for treating carotid artery disease. Carotid endarterectomy (CEA) has been shown to reduce the incidence of stroke in patients with symptomatic and asymptomatic carotid stenosis. [1, 2, 3, 4] With ongoing advances in endovascular technology, growing experience with CAS on the part of interventionalists, and an increasing focus on training and credentialing, [5] CAS has become an alternative to CEA for treatment of patients with carotid artery disease, though it has not supplanted CEA. [6]
Indications
Indications for CAS include the following:
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Inability to tolerate general anesthesia for CEA
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History of damage to the contralateral vocal cord (previous CEA or neck surgery)
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Previous neck surgery on the ipsilateral side
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Neck irradiation
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Restenosis after CEA
Contraindications
Contraindications for CAS include the following:
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History of allergic reaction to intravenous (IV) contrast material
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Unfavorable anatomy
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Unstable carotid plaque
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Unstable aortic arch plaque
Technical Considerations
Anatomy
The principal arteries supplying the head and neck are the two common carotid arteries (CCAs). These vessels ascend in the neck, where each divides into two branches, the external carotid artery (ECA; supplying the exterior of the head, the face, and the greater part of the neck) and the internal carotid artery (ICA; supplying to a great extent the parts within the cranial and orbital cavities).
For more information about the relevant anatomy, see Arterial Supply Anatomy and Arteries to the Brain and Meninges.
Best practices
In February 2016, the Society for Cardiovascular Angiography and Interventions (SCAI) and the Society for Vascular Medicine (SVM) published an expert consensus statement aimed at providing guidance on physician training and credentialing for CAS so as to facilitate the incorporation of this procedure into clinical practice within cardiovascular medicine programs focused on preventing stroke. [5]
Outcomes
Naylor et al, in a prospective, randomized trial of CEA versus CAS for symptomatic patients with greater than 70% internal carotid artery stenosis, found that all 10 of the CEA patients proceeded without any complications, whereas five of the seven CAS patients had an ischemic stroke within 30 days of the procedure. [7] The trial was stopped because of the dramatically bad outcome in the endovascular group.
Brooks et al, in a randomized study of 104 patients presenting with cerebrovascular ischemia related to internal carotid artery stenosis who underwent either CEA (n = 51) or CAS (n = 53), reported one death in the CEA group and one transient ischemic attack in the CAS group. [8] CAS was equivalent to CEA and did not carry an increased risk of major complications (ie, death or stroke).
These authors subsequently published 10-year outcomes for 173 patients. Half of the patients had died from other conditions in this period. They did not find any difference in long-term protection against ipsilateral stroke in either group. Overall, the risk of heart attack was high among patients randomized to CEA. [9]
In the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), a multicenter clinical trial in which 504 patients with carotid stenosis were randomly assigned to undergo either CEA (n = 253) or CAS (n = 251), there was no substantial difference in the rate of ipsilateral stroke over a 3-year follow-up period. [10] However, the results of surgery were worse as compared to surgical standards for CEA; moreover, cerebral protection devices (CPDs) were used in only 27% of the patients who underwent CAS.
The Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) trial, an industry-sponsored randomized, controlled trial that included 334 high-risk surgical patients who underwent either CAS or CEA, concluded that CAS was superior to CEA among high-risk surgical patients. [11] The primary end points were combined death, stroke, and myocardial infarction (MI). An asymptomatic rise in troponin levels was regarded as MI, and the higher rate of MI among patients who underwent CEA shifted the balance in favor of CAS.
In the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST), which included 2502 patients who were randomly assigned to undergo either CEA or CAS, the combined risk of death, MI, or stroke (the primary end points) was comparable for the two procedures (6.8% for CEA vs 7.2% for CAS). [12] However, the incidence of stroke was 2.3% for CEA versus 4.1% for CAS. The incidence of MI was 2.3% for CEA versus 1.1% for CAS. Stroke is a disabling event, and extreme caution should be observed in interpreting the results from CREST.
A subsequently published subanalysis of the CREST trial [13] showed that restenosis and occlusion rates were similar up to 2 years after CEA and CAS.
In the multicenter randomized CASWEP (Carotid Artery Stenting Without Embolic Protection) trial (N = 279), Gorgulu et al compared the clinical outcomes in selected symptomatic and asymptomatic patients with significant carotid artery stenosis who underwent either CAS without CPD (n = 140) or CAS combined with CPD (n = 139). [14] They found no significant differences with respect to periprocedural in-hospital TIAs, ipsilateral stroke, death, or new ischemic brain lesions on postprocedural diffusion-weighted magnetic resonance imaging (DW-MRI).
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Key steps in carotid stenting. Image courtesy of Kurt Mansor, Jobst Vascular Institute.
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Images show vessel before and after carotid artery stenting. Image courtesy of Cheong Lee, MD.
