The treatment of patients with asymptomatic carotid disease (bruit, stenosis, or occlusion) continues to be somewhat controversial, although recent data have clarified some aspects. It is generally accepted that all patients with asymptomatic carotid bruits should be evaluated with a complete neurologic examination, including ophthalmoscopy and one or more of the noninvasive carotid artery techniques, such as carotid duplex ultrasonography, computed tomography angiography, and magnetic resonance angiography. There are some data to suggest that additional imaging assessment beyond the evaluation of carotid stenosis may be helpful in assessing the risk of stroke in the setting of carotid atherosclerosis. These include magnetic resonance imaging (MRI) evaluating for the presence of lipid-rich necrotic core, intraplaque hemorrhage, and thinning and rupture of a fibrous cap. Transcranial Doppler (TCD) assessment for the presence or absence of microemboli may also help to quantify stroke risk in asymptomatic carotid stenosis.

If abnormalities suggest relatively high-grade lesions (stenosis of >60%), other high-risk imaging features (if MRI plaque evaluation or TCD assessment is utilized), or if there is evidence of cholesterol or fibrin platelet retinal emboli, then aggressive atherosclerosis risk factor modification and antiplatelet therapy generally are used with or without carotid endarterectomy (CEA) or carotid angioplasty with stent placement (CAS), which may benefit some of these patients. The estimated risk of ipsilateral stroke in patients with asymptomatic carotid atherosclerosis (stenosis of ≥50%) is approximately 0.5% to 1.0% annually, although screening low-risk populations for asymptomatic carotid artery stenosis is not recommended. In the setting of asymptomatic carotid occlusive disease, aspirin typically is selected as the antiplatelet agent. There is no specific indication in these patients for clopidogrel, dual antiplatelet therapy with aspirin and clopidogrel, or aspirin in combination with sustained-release dipyridamole, unless they require one of these treatments for a nonneurologic indication. Other medical management includes healthy lifestyle changes (see Chapter 24), use of a statin, and treatment of any other associated risk factors, such as elevated blood pressure and diabetes.

Data from the Asymptomatic Carotid Atherosclerosis Study (ACAS) and the Medical Research Council Asymptomatic Carotid Surgery Trial (ACST) indicate that selected patients with reduction in the diameter of the carotid artery of greater than 60% may benefit from CEA in addition to the use of aspirin and management of risk factors. It is important to realize that there are different measurements of carotid artery stenosis; for example, 70% stenosis recorded using the
criteria used in the North American Symptomatic Carotid Endarterectomy Trial equals approximately 80% European Carotid Stenosis Trial stenosis (Fig. 25-1). In ACAS, participating surgical investigators performed CEA with a combined perioperative morbidity and mortality rate of less than 3%. The risk during 5 years for the primary outcome (any stroke or death within 30 days postoperatively or any ipsilateral stroke or death from stroke thereafter) was 5.1% (˜1% per year) for patients who were treated surgically and 11.0% (˜2% per year) for those who were treated without operation. The relative risk reduction was 53%, with a 66% reduction in men (statistically significant) and 17% in women (not statistically significant). The perioperative morbidity and mortality were higher in women, contributing to the lack of clear benefit in women. Evaluation of secondary end points revealed that the differences between the operation and nonoperation groups with respect to total stroke and ipsilateral major stroke and death were not statistically significant, although there was a trend in favor of operation.