Carotid artery stenosis

Carotid artery stenosis (CAS) is an atherosclerotic, degenerative disease of the common carotid artery and internal carotid artery. Risk factors include advanced age, tobacco use, arterial hypertension, and diabetes mellitus. Depending on the extent of stenosis, ischemia in the carotid perfusion territory can result in amaurosis fugax, transient ischemic attack (TIA), or stroke. Carotid duplex ultrasonography is the initial test of choice for evaluating the carotid artery and measuring the degree of stenosis. Management depends on the degree of stenosis and patient factors (e.g., life-expectancy, comorbidities). Lifestyle modifications, antiplatelet and statin therapy, and risk factor modifications (e.g., with antihypertensive therapy) are recommended for all patients and should be continued indefinitely. Carotid revascularization is recommended for severe carotid stenosis and may be considered for moderate carotid stenosis if the periprocedural risks are acceptable. Screening for asymptomatic carotid stenosis is controversial.

• Symptomatic carotid stenosis: symptoms attributable to carotid stenosis within the past 6 months
• Asymptomatic carotid stenosis: no recent (< 6 months) symptoms attributable to carotid artery stenosis

• Atherosclerosis
• Risk factors for cardiovascular disease
  • Advanced age
  • Tobacco use
  • Arterial hypertension
  • Diabetes mellitus

• Many patients are asymptomatic.
• Symptomatic patients may present with
  • Transient ischemic attacks
  • Symptoms of ischemia of the common carotid artery territory, such as:
    • Ipsilateral amaurosis fugax
    • Contralateral weakness, contralateral sensory deficits (ischemic stroke)
• Examination findings
  • Carotid bruit: a pathologic sound heard on auscultation over the carotid artery that is caused by turbulent blood flow ^[1]
  • Hollenhorst plaque on fundoscopy ^[2]

Carotid artery stenosis does not typically cause vertigo, lightheadedness, or syncope.

General principles ^[3][4][5]

• Evaluate for and manage acute neurological symptoms.
  • Ischemic stroke (anterior circulation stroke): See “Acute management checklist for ischemic stroke.”
  • TIA: See “Acute management checklist for TIA.”
• Perform carotid artery imaging in all patients with symptomatic carotid stenosis.
  • Clinically significant carotid stenosis: narrowing of the carotid artery ≥ 50%
  • Moderate carotid stenosis: narrowing of the carotid artery by 50%–69%
  • Severe carotid stenosis: narrowing of the carotid artery 70%–99%
• Screening for asymptomatic carotid stenosis is controversial and is detailed in the “Prevention” section below.

Noncontrast CT head or MRI brain is indicated for all patients with ischemic stroke or TIA.

Carotid artery stenosis typically occurs within 2 cm of the common carotid artery bifurcation. ^[6]

Carotid duplex ultrasound (CDUS)

CDUS permits direct visualization of the vessel wall and flow measurement at the site of the stenosis by color Doppler ultrasound.

• Indications: first-line imaging modality for suspected symptomatic carotid stenosis ^[7][8]
• Findings ^[4][6][9]
  • Focally increased velocity of blood flow (high-grade stenosis) or absence of blood flow (total occlusion) ^[10]
  • Increased peak systolic velocity
  • Increased thickness of the intima-media

Magnetic resonance angiography (MRA) or CT angiography (CTA)

• Indications ^[4]
  • Confirmatory test if CDUS findings are suggestive of carotid stenosis
  • Simultaneous evaluation of head and neck vessels in patients with ischemic stroke ^[11]
• Findings ^[8]
  • Luminal narrowing at the site of the stenosis
  • Carotid plaques and calcification
• Additional considerations
  • The advantages of MRA include the lack of ionizing radiation and iodinated IV contrast.
  • MRA has a tendency to overestimate the degree of stenosis. ^[4]
  • CTA is suitable for patients with contraindications for MRI (e.g., implanted devices, claustrophobia). ^[8]

Digital subtraction angiography (DSA)

DSA is commonly considered the gold standard for evaluating CAS. ^[5][8][12]

• Indications ^[4]
  • Consider if CDUS is inconclusive in patients who cannot undergo CTA or MRA.
  • Preprocedural planning (i.e., before carotid endarterectomy or carotid artery stenting)
• Findings: Similar to CTA or MRA
• Important consideration: DSA is an invasive procedure with a higher risk of mortality and stroke than imaging modalities with comparable diagnostic accuracy (e.g., CTA).

General principles ^[3][4][13]

• All patients: Initiate long-term management of ASCVD.
• Symptomatic carotid stenosis: Revascularization is typically indicated.
• Asymptomatic carotid stenosis: Consider revascularization for patients with severe carotid stenosis. ^[10]
• Bilateral carotid stenosis is uncommon; management is similar to that of unilateral carotid stenosis. ^[14]
• Consult specialists as needed.

Medical management ^[3][15]

Carotid stenosis is a type of ASCVD and measures to prevent further progression of atherosclerosis should be initiated in all patients and continued indefinitely (i.e., even after carotid revascularization).

• Lifestyle modifications for ASCVD prevention, e.g., smoking cessation, heart-healthy diet
• Lipid-lowering therapy: long-term high-intensity statin therapy ^[16]
• Long-term antiplatelet therapy
  • Asymptomatic carotid stenosis: single-agent antiplatelet therapy with aspirin ^[3]
  • Symptomatic carotid stenosis
    • Medical management alone or after carotid endarterectomy: single-agent antiplatelet therapy (e.g., aspirin OR clopidogrel ) ^[4]
    • After carotid artery stenting: short course of dual antiplatelet therapy (e.g., clopidogrel PLUS aspirin for 1 month), followed by long-term single-agent antiplatelet therapy with aspirin ^[4]
• Manage modifiable risk factors for ASCVD (e.g., management of diabetes mellitus, management of hypertension).
• See “Management of ASCVD” and “Reducing subsequent stroke risk” for further details.

Carotid revascularization

Overview ^[3][15][17]

• Timing: ideally performed within 14 days of symptom onset
• Periprocedural optimization: e.g., beta blockers to control blood pressure, initiate statin therapy, withhold clopidogrel as needed ^[4][16]
• Indications : Periprocedural risk and patient life-expectancy, comorbidities, and preferences must also be considered. ^[3][10][18]
  • Symptomatic carotid stenosis ^[17]
    • Severe carotid stenosis: Revascularization is indicated if life expectancy is ≥ 2 years and if the operator's risk of procedural morbidity and mortality is < 6%. ^[15]
    • Moderate carotid stenosis: The benefit of revascularization depends on patient-specific factors
  • Asymptomatic patients with severe carotid stenosis: Consider revascularization if the operator's risk of procedural morbidity and mortality risk is low (< 3%). ^[4][17]
• Contraindications ^[3][18]
  • Carotid stenosis < 50%
  • Chronic complete carotid occlusion
  • Severely disabling stroke

Modalities ^[4][13][17]

Carotid endarterectomy (CEA) is usually considered the first-line treatment for carotid stenosis. If the patient is not a good candidate for surgery or the lesion characteristics preclude surgical treatment, carotid artery stenting may be preferred.

• Carotid endarterectomy: a surgical procedure in which the inner lining of a carotid artery is removed, along with any associated atherosclerotic deposits
  • Advantages: lower periprocedural stroke rate than carotid artery stenting, especially in patients > 70 years of age ^[5][15]
  • Disadvantages
    • Higher risk of periprocedural myocardial infarction than stenting
    • Potential complications include cranial nerve palsy.
    • Potentially difficult in patients with prior neck irradiation and/or surgery
• Carotid artery stenting: angioplasty and stenting of the carotid artery (via a transfemoral or transcarotid approach)
  • Advantages: an alternative to surgery in patients with poor surgical access or increased risk of perioperative complications ^[5]
  • Disadvantages: higher risk of periprocedural stroke than CEA
• Carotid artery bypass grafting: Uncommonly required; may be considered for recurrent or bilateral severe carotid stenosis. ^[14][19]

• Stroke : The annual risk of stroke is 0.5–1% in patients with asymptomatic carotid stenosis > 50%.
• Myocardial infarction
• See also “Complications of endarterectomy.”

We list the most important complications. The selection is not exhaustive.

Recommendations for the screening for asymptomatic carotid stenosis vary. As of 2021, the US Preventive Services Task Force (USPSTF) recommends against screening for asymptomatic individuals, including those with cardiovascular risk factors and carotid bruits. However, other guidelines suggest screening for carotid stenosis in asymptomatic individuals with a carotid bruit and/or risk factors for cardiovascular disease who are potential candidates for carotid intervention.

• Indications: Consider screening for asymptomatic carotid stenosis in individuals with any of the following ^[1][4][18]
  • Carotid bruit (controversial)
  • Known atherosclerotic cardiovascular disease
  • Known peripheral vascular disease
  • Individuals ≥ 65 years of age with multiple risk factors for cardiovascular disease
  • Prior to a CABG
• Screening modalities: noninvasive imaging is preferred (e.g., CDUS, CTA, MRA) ^[8]
• Management: See “Treatment” section for details if significant (≥ 50%) asymptomatic carotid stenosis is detected on screening.

• One-Minute Telegram 65-2022-1/3: 2022 U.S. Preventive Services Task Force: summary of recommendations
• One-Minute Telegram 41-2021-2/2: 2021 U.S. Preventive Services Task Force: Summary of recommendations

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