Carotid Endarterectomy and Carotid Angioplasty and Stenting

Introduction

Large-vessel arteriosclerotic disease and stenosis, most commonly of the extracranial carotid artery bifurcation and simply referred to as carotid stenosis, accounts for 15–20% of cerebral ischemic events. The two main mechanisms for these events are hemodynamic compromise, as the internal carotid artery (ICA) diameter is reduced by at least 70%, and artery-to-artery embolization from an ulcerated plaque. The carotid bifurcation is prone to arteriosclerotic plaque formation because of its geometric configuration resulting in reduced wall shear stress. Common risk factors for carotid stenosis include increasing age, smoking, hypertension, diabetes mellitus, coronary artery disease, peripheral vascular disease, chronic renal failure, and other metabolic abnormalities . Both carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS) are established interventions for select patients with carotid stenosis ( Table 151.1 ).

Table 151.1

Summary of Notable Clinical Trials

Carotid Endarterectomy	Carotid Angioplasty and Stenting
Symptomatic	SAPPHIRE
NASCET	CREST
ECAS	SPACE and SPACE II
VACS	EVA-3S
Asymptomatic	ICSS
ACAS
Veterans Administration Cooperative Asymptomatic Trial
CASANOVA
Mayo Asymptomatic Carotid Endarterectomy Trial
ACST

Carotid Endarterectomy

In 2002, approximately 134,000 CEAs were performed in the United States for both symptomatic and asymptomatic carotid stenoses . Three major randomized controlled trials compared CEA with the best medical therapy for symptomatic carotid stenosis.

North American Symptomatic Endarterectomy Trail

A total of 2885 patients with a TIA (transient ischemic attack) or minor stroke within 120 days and ipsilateral ICA stenosis of >30% were randomized to either the best medical therapy (including aspirin) or the best medical therapy and CEA . The study was terminated early because of a considerable advantage for CEA. The ipsilateral stroke rate at 2 years in patients with ≥70% carotid stenosis was 26% in the medical group and 9% in the CEA group. For moderate stenosis (50–69%), the 5-year ipsilateral stroke rates were 22% and 15%, respectively. In the North American Symptomatic Carotid Endarterectomy Trial (NASCET) the degree of stenosis was determined using angiography and calculated using the following formula: % stenosis = 1 − [residual lumen diameter of the most stenotic portion of the ICA (mm)/lumen diameter of normal ICA distal to stenosis (mm)] × 100. In North America and other parts of the world the method has been widely adopted since it was developed.

European Carotid Surgery Trial

A total of 3024 patients with TIA, retinal infarction, or minor stroke within the previous 6 months and ipsilateral ICA stenosis were randomized to either the best medical therapy (aspirin was an option, but not required) or the best medical therapy and CEA . In the European Carotid Surgery, the degree of stenosis was determined on angiography by comparing the diameter of the lumen at the most stenotic segment of the ICA with the assumed original diameter of the lumen at that site resulting in higher degrees of stenosis than those in the NASCET. The 3-year risk rates of major stroke or death in patients with ≥60% carotid stenosis, corresponding to approximately ≥80% in the NASCET, was 26% in the medical group and 14% in the CEA group.

Veterans Affairs Cooperative Study on Symptomatic Stenosis

This study enrolled 197 men with symptomatic carotid stenosis and randomized between the best medical therapy (including aspirin) and the best medical therapy and CEA . The trial was prematurely terminated as the NASCET and ECAS trial data were published. At an average follow-up of approximately 1 year the stroke rate in patients with >50% stenosis was 19% in the medical group and 7% in the CEA group.

Data from a pooled analysis including over 6000 patients from the NASCET, ECAS trial, and Veterans Affairs Cooperative Study on Symptomatic Stenosis (VACS) trial found an increased risk for stroke, with CEA for carotid stenosis of <30%, no effect for stenosis of 30–49%, a marginal benefit (absolute risk reduction of 4%) for stenosis of 50–69%, and absolute benefit (absolute risk reduction of 16%) for stenosis of ≥70% . The benefit of CEA strongly depends on the perioperative complication rate. For patients with stenosis of ≥70% a complication rate of greater than 6% will offset the benefits of CEA, making the American Heart Association to recommend that CEA can only be performed by surgeons with a complication rate below that. Further analysis of the NASCET has offered insights into various aspects concerning the management of carotid stenosis. Patients with ulcerated plaques in the medical group had dramatically higher stroke rates and those in the CEA group had higher rates of perioperative complications. Patients with hemispheric ischemia in the medical group were at a higher risk for stroke than patients with retinal ischemia. Although there was direct correlation between stroke risk and the degree of stenosis in the medical group, patients with near occlusion had a lower risk of stroke compared to patients with 70–89% stenosis. Contralateral occlusion was associated with increased stroke risk in the medical and CEA groups. Intraluminal thrombus conferred increased risk in the medical and CEA groups. There was a greater net benefit with CEA in older patients with ≥50% stenosis.

Carotid stenosis is common and affects approximately 7% of all females and >12% of all males older than 70 years. Five major randomized controlled trials compared CEA for asymptomatic carotid stenosis.

Asymptomatic Carotid Arteriosclerosis Study

In the Asymptomatic Carotid Arteriosclerosis Study (ACAS) a total of 1662 patients with ≥60% stenosis were randomized to the best medical therapy (including aspirin) or the best medical therapy and CEA . The trial was stopped prematurely because CEA was beneficial over medical therapy alone. The aggregate risk for ipsilateral stroke, any perioperative stroke, or death at 5 years was 11% in the medical group and 5% in the CEA group. Patients with a contralateral occlusion in the medical arm were less likely to have a stroke and CEA in these patients may in fact be harmful.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here