الفهرس 
Anatomy of the Carotid ArteryOnly 14 pages are availabe for public view
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Abstract
egacy trials NASCET, ECST, ACAS and ACST have established the indications for CEA in patients with symptomatic stenosis of >50% and asymptomatic stenosis of >60%. The introduction of protected CAS has been applied primarily to patients at high risk for CEA. Several randomized trials CAVATAS, SAPPHIRE, SPACE, EVA-3S, ICSS and CREST have directly compared CEA with CAS, but only SAPPHIRE compared the two options in the subgroup of patients who were at high risk for CEA, which is the current indication approved by the U.S. Food and Drug Administration (FDA) for CAS in the United States. The Centers for Medicare and Medicaid Services have issued several CAS national coverage decisions that provide coverage for selected (>70% symptomatic) patients at high risk for CEA using FDA-approved devices and for research subjects in CAS studies. (Matsumura et al., 2012)
The CREST and ICSS results had powerful additions to the body of literature on the relative merits of CEA and CAS as treatments for the continuing problem of carotid artery stenosis as a cause of stroke. Both studies demonstrate that outcomes for both CEA and CAS have improved significantly compared with results obtained in earlier RCTs, a trend that also holds true for MT.
Using the primary end point described in the CREST study and from the stroke or death outcome perspective, CEA is superior to CAS in both asymptomatic and symptomatic patients undergoing invasive treatment. Even using the more widely accepted end point of stroke or death, the CREST and ICSS results suggest that a distinct improvement in both CEA and CAS outcomes has taken place since the NASCET and ECST results were published. The outcomes of CEA and CAS are unclear in patients excluded from these trials because of high surgical risk or other risk factors. If SAPPHIRE is taken as any indication, the risk of stroke or death will be higher in such patients in both treatment groups. Are there patients with moderate to severe carotid artery stenosis for whom CAS is the superior method? A notable finding in CREST is the trend indicating that CAS may be superior to CEA in younger patients (<70 years), a result that will require further verification. Nonetheless, these findings suggest that CAS may be the superior treatment for carotid occlusive disease in some patients. A preplanned meta-analysis of the pooled EVA-3S, SPACE, and ICSS trials provides additional support for this age effect on stroke and death outcomes for CAS versus CEA. (Perkins et al., 2010)
The long-running battle among different specialties over management of carotid disease heated up again, with the society representing interventionalists charging that the group representing vascular surgeons is reneging on a hard-won compromise agreement.
At the start of 2011, the American College of Cardiology (ACC), American Heart Association (AHA), Society for Cardiovascular Angiography and Interventions (SCAI), American Academy of Neurology, and 10 other professional societies, including the Society for Vascular Surgery (SVS), released new guidelines on stenting and surgery in the management of patients with extracranial carotid and vertebral artery disease. The guidelines, released soon after the publication of the CREST trial, stated that carotid stenting is an acceptable alternative to carotid endarterectomy for symptomatic patients at average or low risk of complications, with stenosis greater than 70% on duplex ultrasonography.
But while the SVS signed off on that multispecialty guidance, in September 2011 the group released its own carotid disease management guidelines. The SVS document states that stenting should be reserved for symptomatic patients with stenosis of 50% to 99% at high risk for surgery and that endarterectomy surgery should be the first-line therapy for most symptomatic patients with stenosis of 50% to 99% and asymptomatic patients with stenosis of 60% to 99%.
The multispecialty guidelines recommend stenting as an ”alternative” to endarterectomy in symptomatic patients where the periprocedural risk of stroke with stenting is low, while the SVS guidelines recommend stenting symptomatic lesions only when risk with surgery is thought to be high. The multispecialty guidelines recommend stenting as an alternative in asymptomatic patients in some selected circumstances, but the SVS guidelines state stenting of asymptomatic patients should be confined to clinical trials.
Important new data were published after the release of the multispecialty guidelines, including a meta-analysis of 13 trials and nearly 7500 patients, showed that, compared with endarterectomy, carotid artery stenting significantly increases the risk of any stroke and decreases the risk of MI. (Murad et al.)
Vascualr surgeons attacked the multispecialty guidelines for being “non-declarative”, using the words “alternative” and “highly selective” leaving the interpretation of the guidelines open to the physician understanding.
On the other hand, other signatories to the multispecialty guidelines attacked SVS for publishing its own ”discordant” guidelines that contradict the multisociety guidelines it signed off on. The Society for Cardiac Angiography and Interventions (SCAI) is planning to publish a rebuke disapproving SVS’s decision. (SCAI president revealed in heartwire journal)
In this ongoing vascular surgeons, interventionalists clash over guidelines, interventionalists argued that the CREST results justify presenting both stenting and surgery as options for their patients, but SVS testified that surgery is still the best option in these patients, because the 30-day stroke rate was significantly higher with stenting than surgery in CREST.
WHAT TO RECOMMEND TO THE PATIENT?
Current RCT results indicate that outcomes are improving for patients requiring treatment for carotid artery stenosis, whether for intervention or MT. The stroke outcome benefits of intervention versus MT alone for patients with a symptomatic carotid artery stenosis of greater than 70% have decreased since the initial RCTs as a result of improvements in MT. Nonetheless, intervention continues to confer an outcome benefit in this patient group. Clearly, a higher stroke risk is associated with CAS than with CEA when patients with symptomatic high-grade carotid occlusion are not differentiated. On the other hand, CEA is associated with higher incidence of MI and cranial nerve injuries. However, the CREST results suggest that outcomes are not significantly different between CAS and CEA when they are performed at centers with experienced proceduralists and when an aggregate end point of MI and stroke is used. Furthermore, patients younger than 60 years may have an equivalent or better stroke outcome with CAS versus CEA, and those younger than 70 years may have an equivalent or better aggregate outcome with CAS. For patients older than 70 years with symptomatic carotid artery stenosis, CEA remains the best option. However, for those at high risk for surgery, CAS will likely provide a benefit compared with MT. The same considerations apply to those with lower-grade (50%-69%) symptomatic carotid artery stenosis, with the understanding that the outcome benefit of intervention versus MT alone is significantly decreased.
According to the recent inter-collegiate Australasian CAS guidelines, “CAS may be considered as a treatment option for patients with symptomatic severe carotid stenosis who are at high risk of stroke but are surgically unsuitable for CEA.” This includes specific patient subgroups and conditions, namely (1) postradiation therapy, (2) block dissection of the neck, (3) in situ tracheostomy, (4) recurrent stenosis following previous CEA, (5) severe cervical spine arthritis, (6) surgically inaccessible carotid stenosis (e.g., obesity and high carotid bifurcation), (7) contralateral recurrent laryngeal nerve injury, and (8) contralateral internal carotid artery occlusion. Apart from these conditions, CAS should not be considered as an alternative to CEA for the management of symptomatic carotid stenosis except in patients <70 years and those participating in randomized trials. (Carotid Stenting Guidelines Committee, 2011)
The smaller stroke risk reduction benefit obtained in early RCTs for patients with asymptomatic carotid occlusive disease undergoing CEA versus MT alone makes the decision of selecting intervention (CAS or CEA) challenging to both the clinician and the patient. The reduction in strokes achieved with current MT (approximately 50% lower incidence than that reported in ACAS) has doubled the number of patients needed to undergo CEA to reduce the number of strokes by 1. Ongoing studies comparing intervention with optimal MT in patients with asymptomatic carotid artery stenosis of greater than 50%, such as SPACE-2, may shed further light on this issue. Ongoing trials ACT-I and ACST-2 are designed to compare the early and long-term results of CEA versus CAS and best medical management in asymptomatic patients. For now, this decision is best reached after considering all comorbid conditions and anatomic issues for a given patient, with the understanding that stroke risk reduction outcome benefits are likely to be small.
Finally, in clinical practice, a tremendous amount of physician-to-physician variability is observed to the referral of higher-risk patients for CEA versus CAS, and decisions often seem to be influenced by physician subspecialty, subjective biases, and incomplete knowledge of existing data, which to date have not been well summarized.