Elsevier

Mayo Clinic Proceedings

Volume 79, Issue 9, September 2004, Pages 1197-1208
Mayo Clinic Proceedings

Symposium on Cerebrovascular Diseases
Carotid Revascularization for Prevention of Stroke: Carotid Endarterectomy and Carotid Artery Stenting

https://doi.org/10.4065/79.9.1197Get rights and content

Carotid endarterectomy (CEA) has been used for the past several decades in patients with carotid occlusive disease. Large randomized controlled trials have documented that CEA is a highly effective stroke preventive among patients with carotid stenosis and recent transient ischemic attack or cerebral infarction. In asymptomatic patients with carotid stenosis, clinical trial data suggest that the degree of stroke prevention from CEA is less than among symptomatic patients. However, otherwise healthy men and women with an asymptomatic carotid stenosis of 60% or greater have a lower risk of future cerebral infarction, including disabling cerebral infarction, if treated with CEA compared with those treated with medical management alone. More recently, carotid artery stenting has been performed increasingly for patients with carotid occlusive disease. As technology has improved, procedural risks have declined and are approaching those reported for CEA. The benefits and durability of CEA compared with carotid artery stenting are still unclear and are being studied in ongoing randomized controlled trials.

Section snippets

RCTS OF CEA FOR SYMPTOMATIC DISEASE

Randomized controlled trials of CEA date to the 1960s.5 The efficacy results of the larger, more recent trials are shown in Table 1.6, 7, 8, 9 The North American Symptomatic Carotid Endarterectomy Trial (NASCET)6 and the European Carotid Surgery Trial (ECST)8 are perhaps most relevant to today's decision making. The results of these trials at 30 days revealed that CEA could be performed without excess risk. The 30-day combined rates of stroke and death for patients with 70% or greater stenosis

RCTS OF CEA FOR ASYMPTOMATIC DISEASE

Randomized controlled trials have examined the potential benefit of CEA for patients with stenosis greater than 50% to 60% in the absence of symptoms. Benefit has been established (Table 218, 19, 20, 21) for the populations studied in these trials. In ACAS,19 1662 patients with stenosis of 60% or greater were randomized. The 5-year ipsilateral stroke rate plus any 30-day perioperative ipsilateral stroke or death rate was 11% in the medical group and 5.1% in the surgical group. The absolute risk

RESULTS FROM LARGE DATABASES AND FROM LARGE CASE SERIES

A fundamental problem with RCTs is the limit on generalizability to clinical practice. With each inclusion and exclusion criterion, segments of the general population are excluded from the study. Results from analysis of large databases26, 27, 28 such as that of Medicare29, 30, 31 and registries in Canada32, 33, 34, 35 have been reported, which allow comparison of RCT results to results of less restricted populations (Table 327,28,30,32,33,36,37). Most carotid operations are performed in the

CEA IN THE SETTING OF INCREASED PERIOPERATIVE RISK

Large case series43,47, 48, 49 of CEA address the concept of high risk. The degree of interventional risk is of fundamental importance at many centers today in selecting treatments for symptomatic and asymptomatic carotid artery disease. For some surgeons, the group with unacceptable surgical risk is extremely small, and they argue that the number of such patients has become smaller over time with advances in perioperative management. For carotid interventionalists, high-risk patients may be

CAS FOR PREVENTION OF STROKE

Coronary artery stenting has become the preferred procedure for most patients with coronary artery disease who require coronary revascularization. The alternative surgical therapy, CABG, is an extremely effective coronary artery intervention and is still the preferred treatment for selected patients. For carotid artery disease, the preferred surgical intervention, CEA, is a much less invasive operation than CABG. Thus, the differences between CEA and CAS are smaller from the viewpoint of the

RCTS OF CAS COMPARED WITH CEA

The first large RCT of carotid angioplasty was the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS).58 CAVATAS was designed as an exploratory trial, and the degree of carotid stenosis was not specified. Having ipsilateral neurologic symptoms was not required for inclusion in the trial, but only about 10% of randomized patients were asymptomatic or had symptoms 6 months before randomization. At 30 days after the procedure, the disabling stroke or death rate was similar for

MULTICENTER STUDIES AND REGISTRIES OF CAS

Randomized controlled trials are preferable as sources of information to compare medical treatments. However, in the development of a treatment technique such as CAS, single-center case series, multicenter registries, and multicenter trials of the new technique can lay the needed groundwork (Table 549, 64, 67, 68, 69). The best design of RCTs depends on preliminary short-term and longer-term results. The timing of RCTs depends on the maturity of the technology, adequate experience of the

LARGE CASE SERIES OF CAS

Large case series have been reported from cardiology, neurosurgery, and interventional radiology centers. The 30-day perioperative stroke and death rates have been comparable to those reported for CEA in symptomatic patients with characteristics similar to those included in NASCET and ECST. However, for asymptomatic patients, the perioperative stroke and death rates have been higher than the 2.1% rate reported for the patients who underwent CEA in ACAS and ACST.

Results from these case series

EMBOLIC PROTECTION DEVICES AND CAS

For patients with 80% to 90% stenosis of the internal carotid artery, atherosclerotic plaque presents the interventionalist with a minimal residual lumen of less than 2 mm and on occasion, less than 1 mm. Predilation of such lesions is sometimes necessary to allow deployment of the stent. Postdilation of the stent is frequently necessary to keep the immediate postdeployment stenosis less than 30%. Passing the guidewire, use of the balloon, and placement of the stent all involve contact with the

DURABILITY OF CEA COMPARED WITH CAS

Recurrent stenosis is a concern with both CEA and CAS. For stenting, differential gene expression88 and acute89 and chronic90 inflammation may be important. Data from case series76,91, 92, 93 are available for comparison with CEA, but inference is limited because of differences in patient populations and because of the potential effect of risk factor reduction with statins and other treatments. These treatments could vary among studies, particularly those performed at different times.

COMPARISON OF CEA AND CAS

Evidence-based decision making in the selection of carotid disease treatment has become complex. For symptomatic and asymptomatic patients with the conventional risk factors of the cohorts studied in NASCET, ECST, ACAS, and ACST, indications for CEA are relatively well defined:

  • •

    Symptomatic men and women, aged 80 years or younger, with 50% or greater carotid stenosis if surgical risk for stroke and death is 6% to 7% or less.

  • •

    Asymptomatic men and women, aged 80 years or younger, with 60% or

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      In the SAPPHIRE trial, at 1 year, 122 patients in the endovascular group and 96 in the CEA group underwent follow-up ultrasonography. One patient (0.8%) in the stent group and four patients in the CEA group (4.2%) had 70% or greater stenosis (P = .17); 20% of patients in the stent group and 31% of patients in the CEA group had 50% or greater stenosis (P = .06).35 According to AHA/ASA guidelines, CAS may be considered in patients who have symptomatic severe stenosis (> 70%) in whom the stenosis is difficult to access surgically, who have medical conditions that greatly increase the risk for surgery, or who have other specific characteristics such as radiation-induced stenosis or restenosis after CEA.

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