**3. Utility of advanced imaging carotid artery beyond carotid duplex ultrasound**

Duplex ultrasound is an excellent tool to diagnose ECAS.(Eagle, Guyton et al. 1999) However there are certain inherent errors that can occur with duplex. The presence of calcification at the site of stenosis may cause underestimation of degree of stenosis; similarly contralateral occlusion may lead to falsely elevated velocities in the ipsilateral carotid artery leading to overestimation of the degree of stenosis. (Mitchell E 2004) In such situations additional imaging with computed tomography angiography (CTA) or magnetic resonance angiography (MRA) may further characterize the degree of stenosis as well as provide insight on plaque charac‐ teristics, aortic pathology and intracranial ICA abnormalities. Given the excellent images rendered by CTA or MRA, conventional angiography is rarely required for determining degree of stenosis among those with normal or minimally impaired renal function. For those with moderate to severe chronic kidney disease, MRI may be relatively contraindicated due to the risk of nephrogenic systemic sclerosis and invasive angiography favored over CTA given its lower relative contrast volume and risk of contrast-induced acute kidney injury.

**Recommendation**

pressure below 140/90 mm Hg

(LDL) cholesterol below 100

prevention of stroke in asymptomatic patients

combination of aspirin with clopidogrel

control blood pressure before and after CEA.

indefinitely postoperatively

(25 and 200 mg twice daily,

hours before and after CEA.

pressure before and after CAS.

substituted.

cardiovascular events

mg/dL

Antihypertensive treatment is recommended for patients with hypertension and asymptomatic extracranial carotid or vertebral atherosclerosis to maintain blood

Treatment with a statin medication is recommended for all patients with extracranial carotid or vertebral atherosclerosis to reduce low-density lipoprotein

Patients with extracranial carotid or vertebral atherosclerosis who smoke cigarettes should be advised to quit smoking and offered smoking cessation interventions to reduce the risks of atherosclerosis progression and stroke

Antiplatelet therapy with aspirin, 75 to 325 mg daily, is recommended for patients with obstructive or nonobstructive atherosclerosis that involves the extracranial carotid and/or vertebral arteries for prevention of MI and other ischemic cardiovascular events, although the benefit has not been established for

In patients with obstructive or nonobstructive extracranial carotid or vertebral atherosclerosis who have sustained ischemic stroke or TIA, antiplatelet therapy with aspirin alone (75 to 325 mg daily), clopidogrel alone (75 mg daily), or the combination of aspirin plus extended-release dipyridamole (25 and 200 mg twice daily, respectively) is recommended (*Level of Evidence: B*) and preferred over the

Aspirin (81 to 325 mg daily) is recommended before CEA and may be continued

Beyond the first month after CEA, aspirin (75 to 325 mg daily), clopidogrel (75 mg daily), or the combination of low-dose aspirin plus extended-release dipyridamole

respectively) should be administered for long-term prophylaxis against ischemic

Administration of antihypertensive medication is recommended as needed to

Before and for a minimum of 30 days after CAS, dual-antiplatelet therapy with aspirin (81 to 325 mg daily) plus clopidogrel (75 mg daily) is recommended. For patients intolerant of clopidogrel, ticlopidine (250 mg twice daily) may be

Administration of antihypertensive medication is recommended to control blood

**Table 3.** Recommendations from multisocietal guidelines for extracranial carotid artery stenosis.

The findings on clinical neurological examination should be documented within 24

**Class of Indication**

Management of Carotid Artery Disease in the Setting of Coronary Artery Disease ...

I A

I B

I B

I A

I B

I A

I B

I C

I C

I C

I C

**Level of Evidence** 391

http://dx.doi.org/10.5772/55669

Other factors that may lead to increased stroke risk beyond degree of stenosis, including cerebrovascular reserve (CVR). Severe ECAS reduces cerebral perfusion pressure. Autoregu‐ lation of the cerebral vasculature dilates the cerebral arterioles maximally, and with further reduction in cerebral perfusion, blood flow will eventually decrease, causing impairment in cerebral perfusion leading to stroke. CVR can be assessed by two approaches. the first, CVR can be determined through direct measurements of brain tissue with flow-sensitive imaging through positron emission tomography, CT perfusion or MR perfusion before and after vasodilator stimulation. A second, indirect approach utilizes transcranial Doppler to assess flow velocities distal to the lesion, typically in the middle cerebral artery before and after vasodilatory stimulation, with increase in flow velocities used to indirectly measure CVR. (Gupta, Chazen et al. 2012) In a meta-analysis of patients with severe ECAS, there was an association between impaired CVR and increased stroke risk.(Gupta, Chazen et al. 2012) An incomplete circle of Willis has also been associated with increased ipsilateral cerebral ischemia during carotid cross clamping with CEA.(Manninen, Makinen et al. 2009) and as a risk factor for ischemic stroke (Hoksbergen AW et al. Cerebrovasc Dz 2003;16:191-8) Current guidelines do not comment on use of cerebral perfusion imaging when assessing stroke risk due to insufficient evidence available so far.(Brott, Halperin et al. 2011; Hillis, Smith et al. 2011)
