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Symptomatic Carotid Artery Stenosis
Asymptomatic Carotid Artery Stenosis
The Procedure
Surgical Treatment
Carotid Angioplasty/Stenting
Conclusions

Symptomatic Carotid Artery Stenosis
The severity of carotid artery stenosis strongly correlates with the relative risk of stroke. Through the removal of atherosclerotic plaques, carotid endarterectomy (CEA) restores cerebral blood flow and reduces the risk of cerebral ischemia. While medical therapy clearly plays a role in the management of atherosclerosis in general and carotid artery disease in particular, the results from three major prospective contemporary studies provide compelling evidence for the benefit of CEA versus medical therapy alone. When performed by experienced surgeons, CEA, most prominently, improves the chance of stroke-free survival in high-risk symptomatic patients.

Perhaps the most important study with regard to symptomatic carotid artery disease was the North American Symptomatic Carotid Endarterectomy Trial (NASCET). During this multi-center, prospective trial, patients with symptomatic carotid artery stenoses of 70-99% were randomized to either medical therapy (aspirin and risk factor modification) or medical therapy and CEA. The trial was intended to follow both groups for 5-years but was halted after only 2 years because the stroke reduction benefit of CEA was clear after only a short enrollment period. Interestingly, patients treated with medical therapy alone had a 32% stroke and death rate during the 2-year follow-up period. The CEA group, however, displayed a relative risk reduction of major ipsilateral stroke of roughly 80 percent over that same time frame.

Two other clinical trials have been particularly important in determining the optimal treatment for symptomatic patients with high-grade carotid stenosis as well. While the methodology of The European Carotid Surgery Trial (ECST) and the Veterans Affairs Trial of Carotid Endarterectomy in Symptomatic Carotid Stenosis differed from that of the NASCET, the results suggested a significant benefit in stroke reduction with surgery versus medical therapy alone in this patient cohort.

Results from the extended NASCET recruitment of patients with symptomatic carotid stenosis of a lower grade (<69% stenosis) did reveal a long-term benefit favoring surgery for patients with stenosis of 50 to 69 percent. The benefit was clear in those with hemispheric ischemia or no history of diabetes, but not to the same extent as observed in the high- grade classification trial. Carotid endarterectomy provided no benefit if symptoms occurred in patients with stenoses of less than 50 percent.

Asymptomatic Carotid Artery Stenosis
Asymptomatic carotid artery disease is highly prevalent in the general population, particularly the patient with evidence of other atherosclerotic disease and in the elderly. Compared with symptomatic stenosis, however, most available data suggest that asymptomatic carotid artery stenosis is associated with a relatively low risk of ipsilateral cerebral infarction.

In order to answer the question as to whether patients with symptomatic carotid stenosis were best treated medically or surgically, several clinical trials were conducted. All were criticized for design errors. Until the Asymptomatic Carotid Atherosclerosis Study (ACAS) was instituted, a truly prospective, randomized trial investigating the effect of surgical intervention on asymptomatic carotid lesions had not been adequately conducted. The ACAS was designed to evaluate the combined use of carotid endarterectomy and medical management (aspirin and risk factor modification) versus medical management alone for patients younger than 80 years with asymptomatic carotid artery stenosis of 60 percent or more.

Based on a five-year projection, the ACAS data show that carotid endarterectomy reduced the absolute risk of stroke by 5.9 percent and the relative risk of stroke and death by 53 percent. However, the surgical benefit incorporated a very low aggregate perioperative stroke and death rate of only 2.3 percent, including a permanent arteriographic complication rate of 1.2 percent. Essentially, the benefit of surgical intervention in this patient population is lost unless the operation is performed by an experienced surgeon with documented complication rate (combined arteriographic and surgical) of 3 percent or less. The results of ACAS have been criticized by several authorities based on the superior surgical success within the trial and a belief that such results cannot be duplicated in the surgical community as a whole. Therefore, because of the relatively low risk of stroke in asymptomatic patients, many authorities continue to recommend surgery in asymptomatic patients only when the degree of stenosis is more than 80 percent, as was demonstrated by ECST investigators.

The Procedure
Carotid endarterectomy is performed in the operating room with the patient asleep. A 3 to 4 inch incision is made in the neck over the carotid artery and it's branches are properly isolated. Once the blood flow is controlled, the surgeon opens the artery. He may choose to use a shunt to preserve the blood flow to the brain while the artery is opened. The plaque inside the artery is removed and the artery is closed back up. The procedure lasts between 60 and 90 minutes. It requires an overnight stay in the hospital to monitor blood pressure. Patients usually are able to go home the next day.

Carotid Angioplasty/Stenting
Much attention has recently been given to percutaneous intervention for carotid stenosis - carotid angioplasty / stenting (CAS). As with most percutaneous interventions, the possibility of a groin puncture and same day discharge is very attractive, so enthusiasm for the procedure runs high. Technology aimed at preventing cerebral embolization during CAS continues to advance, and there are recent data to suggest CAS does hold promise for the treatment of highly selected carotid lesions and recurrent stenosis. However, no study to date has shown carotid angioplasty to be superior to surgery with regard to the hard endpoints of stroke and death. In addition, nearly all of the major medical organizations involved in the treatment of carotid artery disease (Society for Vascular Surgery, American College of Cardiology, Society of Cardiovascular and Interventional Radiology, etc.) have jointly stated that the performance of carotid angioplasty outside of a clinical trial or device registry is only indicated in extremely selective individuals. Currently a multi-institutional, prospective, randomized trial comparing CAS and CEA in symptomatic patients is underway. Perhaps at trial conclusion more recommendations can be given to patients with regard to the best therapy for them.

CONCLUSIONS
Surgery for symptomatic carotid artery stenosis has the greatest impact with regard to stroke reduction. However, patients with high grade asymptomatic carotid occlusive disease (>80%) also enjoy a long-term reduction in stroke risk after CEA. The outcomes from surgical intervention have clearly been linked to the experience of the surgeon performing the procedure. All surgeons undertaking CEA should be able to honestly discuss their operative results with their patients to allow the patient to make an informed choice.

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