Management of carotid artery stenosis: endarterectomy or stenting?

Severe atherosclerotic stenosis arising at the origin of the internal carotid artery is an important cause of ischemic stroke. The atherosclerotic lesion may fracture and induce an intraluminal thrombus that results in artery-to-artery embolism to the brain. The thrombus also may cause occlusion of the internal carotid artery, potentially resulting in a hemodynamic cerebral infarction. Management to lower the risk of stroke among people with carotid artery stenosis includes antiplatelet agents and medications to treat the risk factors associated with accelerated atherosclerosis, including hypertension, diabetes mellitus, and hyperlipidemia. Lifestyle changes, including stopping smoking, also are important components of management. Surgical interventions to lower the risk of stroke among people with severe symptomatic (prior ipsilateral transient ischemic attack or stroke) or asymptomatic (commonly found by vascular imaging or auscultation of a carotid bruit) carotid artery stenosis include carotid endarterectomy (CEA) and, more recently, carotid angioplasty and stenting (CAS). Considerable uncertainty exists about the relative indications and usefulness of the 2 procedures. A number of randomized clinical trials in Europe and North America have addressed this issue, with mixed results. In this issue of Mayo Clinic Proceedings, Perkins et al1 review the 2 operations on the basis of the results of these trials. In particular, their perspective is influenced by the results of CREST (the Carotid Revascularization Endarterectomy vs. Stenting Trial) that was led by one of the authors.2 CREST is the largest trial comparing the utility of CEA and CAS, and it enrolled patients with either symptomatic or asymptomatic carotid artery stenosis. CREST reported the lowest rate of perioperative complications of any of the recent trials. The relatively good safety profile of both procedures is a sign of the strenuous certification process for the physicians performing the 2 procedures and probably also reflects the result of technical advances in CAS. The low rate of complications also probably reflects the inclusion of a large number of asymptomatic patients. Perkins et al1 speculate that the results of the recent trials may affect reimbursement decisions by the Centers for Medicare & Medicaid Services and other third-party payers. The authors propose that future trials testing CEA and CAS may wish to include a medical management–only arm to test not only the relative utility of the 2 procedures but also whether revascularization and best medical management are superior to best medical management alone. They also acknowledge that such a clinical trial might be extraordinarily large, complex, and expensive. It is unclear if such a trial could be done in the United States. See also page 1101 Recently, 2 additional reports and an editorial about the relative utility of CEA and CAS have been published. Halliday et al3 described the 10-year results of CEA in the treatment of patients with asymptomatic carotid artery stenosis. The perioperative rate of stroke or death was 3% in this European trial. The subsequent risk of stroke was approximately 2% per year among people not having surgery; the operation reduced this risk by about one-third. By 10 years, the overall risk of stroke (including perioperative events) was 13.4% for those undergoing early operation vs 17.9% with delayed or no CEA. Of particular interest is that approximately 80% of the patients were receiving aggressive medical management, including the use of lipid-lowering medications. Although the net benefit of CEA for asymptomatic stenosis is less than for treatment of patients with an ipsilateral transient ischemic attack or ischemic stroke because of the overall lower risk of stroke, the results of this trial still support the continued recommendation of CEA for treatment of patients with severe asymptomatic stenosis of the internal carotid artery. A meta-analysis of 3 of the recent trials found that perioperative risk of stroke or death was significantly higher with CAS (8.9% [153/1725]) than with CEA (5.8% [99/1708]) (relative risk, 1.53; 95% confidence interval, 1.20-1.95, P=.0006). 4 The investigators concluded that CAS for treatment of people with symptomatic carotid artery stenosis should be avoided among people older than 70 years. Data on the safety and potential efficacy of CAS in younger patients were insufficient to draw a conclusion. The findings of an age relationship for safety and efficacy of CAS in the meta-analysis generally are in agreement with those found in CREST. An accompanying editorial written by Amarenco et al5 concluded that CEA should be considered safer than CAS, particularly when looking at the end points of prevention of ischemic stroke and perioperative stroke or death. They criticized the inclusion of myocardial infarction with asymptomatic cardiac ischemia (as detected by elevated troponin levels and electrocardiographic changes) as a primary safety measure in CREST. The inclusion of the cardiac adverse experiences in CREST is important because the perioperative rate of ischemic stroke was higher with CAS, whereas the cardiac events were more common with CEA. Without the inclusion of the cardiac events, which were described by the CREST investigators as not having an adverse affect on the quality of life, the results of CREST would have shown that CEA was the safer procedure. The currently available periprocedural morbidity/mortality data from several trials, including CREST, have not conclusively shown CAS to be safer than CEA for treatment of either asymptomatic or symptomatic patients. The subsequent risk of ipsilateral stroke appears to be similar with both procedures. However, the long-term durability of CAS has not been established; for example, the rate of recurrent stenosis is unknown. The recently completed trials represent a great deal of effort, and their results should influence patient care. However, endovascular treatment is rapidly changing; increasing numbers of highly trained physicians with additional expertise are using new techniques and equipment that may affect both the future safety and efficacy of CAS. Thus, the currently available data may become irrelevant in a relatively short time. Additional studies comparing CAS and CEA are under way, and their results may reflect the evolution of neurointerventional techniques. Progress in endovascular therapy may mean that recommendations for treatment of patients with ischemic cerebrovascular disease may change in the future. Still, physicians are faced with decisions about the best management of their patients with severe carotid artery stenosis. Although the risks of stroke are higher among patients with a recent ipsilateral transient ischemic attack or stroke, asymptomatic patients also have a sufficient risk to warrant consideration for a local intervention (either CAS or CEA). The arterial narrowing that would lead to surgical treatment should exceed 50% (symptomatic patients) or 70% (asymptomatic patients). Currently, medical management with antiplatelet agents and interventions to treat risk factors for atherosclerosis are fundamental. In general, patients with either symptomatic or asymptomatic moderate-to-severe carotid artery stenosis should first be considered for CEA, and for many of them it remains the best option. These patients should be screened for conditions that would affect the recommendation for CEA (eg, a history of CEA at the site or radiation therapy in the operative field). In these circumstances, CAS may be preferred. Also, CAS may be indicated when the atherosclerotic narrowing is in a location not easily approachable by CEA or if the patient has an occlusion of the contralateral internal carotid artery. Patients considered to have a high risk of cardiac complications, including myocardial infarction, may also best be treated with CAS. Given the results of CREST, younger patients (<70 years) might be candidates for CAS instead of CEA. Both procedures entail considerable risk (eg, potentially disabling stroke), and the desired efficacy of the operations will not be achieved unless the perioperative morbidity and mortality are kept low. Any referring physician should know the safety record of surgical colleagues who will be performing the procedure (either CAS or CEA) and should opt for those with a rate of complications no higher than those achieved by the investigators in CREST.