Carotid stenting

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Muhammad Saad, M.B.B.S.[2]

Overview

Carotid artery stenting (CAS) is a percutaneous, endovascular procedure used to treat carotid stenosis (narrowing of the carotid artery lumen by atheroma). Carotid stenosis may be asymptomatic (diagnosed incidentally on imaging) or symptomatic, presenting with transient ischemic attacks (TIAs) or cerebrovascular accidents (CVAs, strokes). The goal of CAS is to prevent stroke by restoring adequate blood flow through the stenotic internal carotid artery. CAS is performed as an alternative to carotid endarterectomy (CEA), particularly in patients at elevated surgical risk due to anatomic or medical comorbid conditions. Over 14,000 patients have been enrolled in randomized controlled trials evaluating CAS, and the procedure has been shown to be noninferior to CEA in appropriately selected patients.

Approaches to CAS include:

Transfemoral CAS (tfCAS): The traditional approach via femoral artery access, with navigation through the aortic arch to the carotid arteries. An embolic protection device (EPD) is used to capture debris during the procedure.

Transcarotid artery revascularization (TCAR): A newer approach involving direct surgical exposure of the common carotid artery in the neck with temporary carotid flow reversal for cerebral protection, avoiding aortic arch manipulation.

Landmark Studies

CAS vs CEA in Symptomatic Patients

Multiple landmark randomized controlled trials have compared CAS to CEA in patients with symptomatic carotid stenosis:

Trial	Year	N	Population	Key Findings
SAPPHIRE	2004	334	High-surgical-risk; ~70% asymptomatic, ~30% symptomatic; >50% symptomatic or >80% asymptomatic stenosis	CAS noninferior to CEA for primary composite (death, stroke, or MI at 30 days plus death or ipsilateral stroke to 1 year): 12.2% CAS vs 20.1% CEA (P=0.004 for noninferiority). Benefits maintained at 3 years.
EVA-3S	2006	527	Symptomatic; ≥60% stenosis	Stopped early. 30-day stroke or death: 9.6% CAS vs 3.9% CEA (P=0.01).
SPACE	2006	1,214	Symptomatic; ≥50% stenosis	30-day stroke or death: 7.4% CAS vs 6.6% CEA; failed to prove noninferiority of CAS.
ICSS	2010	1,713	Symptomatic; ≥50% stenosis	30-day stroke, death, or procedural MI: 8.5% CAS vs 5.2% CEA (P=0.006). At 5 years, fatal or disabling stroke did not differ significantly.
CREST	2010	2,502	Symptomatic (1,321) and asymptomatic (1,181); ≥50% symptomatic or ≥60% asymptomatic stenosis by angiography	No significant difference in primary composite (periprocedural stroke, MI, or death plus ipsilateral stroke at 4 years): 7.2% CAS vs 6.8% CEA (P=0.51). Periprocedural stroke higher with CAS (4.1% vs 2.3%; P=0.01); periprocedural MI higher with CEA (2.3% vs 1.1%; P=0.03). At 10 years: 11.8% CAS vs 9.9% CEA (HR 1.10; 95% CI 0.83–1.44).

CAS vs CEA in Asymptomatic Patients

Trial	Year	N	Key Findings
ACST-2	2021	3,625	Procedural disabling stroke or death: ~1% in both groups. 5-year nonprocedural stroke: 5.3% CAS vs 4.5% CEA (RR 1.16; P=0.33). No significant difference between CAS and CEA.
ACT-1	2016	1,453	Procedural stroke or death: 2.9% CAS vs 1.7% CEA (not significant). 5-year outcomes comparable.

Revascularization vs Medical Therapy Alone (Asymptomatic Stenosis)

Trial	Year	N	Key Findings
CREST-2 (Stenting Arm)	2026	1,245	CAS + intensive medical therapy vs intensive medical therapy alone. 4-year primary outcome (stroke or death): 2.8% CAS + medical therapy vs 6.0% medical therapy alone (P=0.02; NNT=31).
CREST-2 (CEA Arm)	2026	1,240	CEA + intensive medical therapy vs intensive medical therapy alone. 4-year primary outcome: 3.7% CEA + medical therapy vs 5.3% medical therapy alone (P=0.24; not significant).
ECST-2	2025	429	Low-to-intermediate stroke risk patients (asymptomatic or symptomatic). 2-year interim results: no benefit of revascularization over optimized medical therapy alone (win ratio 1.01; P=0.97).
Meta-analysis (Gao et al.)	2026	3,426	Pooled analysis of SPACE-2, ECST-2, and CREST-2. No significant difference between revascularization and medical management for the primary composite outcome (RR 0.91; 95% CI 0.47–1.74; P=0.77).

Cochrane Systematic Review

A 2020 Cochrane review of 8 trials found that CEA conferred benefit over CAS for early stroke or death (40 vs 66 per 1,000 patients). This benefit was maintained at ≥4 years (235 vs 273 per 1,000). Cranial nerve palsy was less frequent with CAS (5 vs 51 per 1,000). No clear benefit of CEA over CAS was observed in patients aged <70 years.

A meta-analysis of 13 randomized controlled trials (7,484 patients) confirmed that CAS was associated with a higher risk of any stroke (RR 1.45; 95% CI 1.06–1.99) but a lower risk of periprocedural myocardial infarction (RR 0.43; 95% CI 0.26–0.71) compared to CEA.

Transcarotid Artery Revascularization (TCAR)

TCAR has emerged as an alternative to transfemoral CAS (tfCAS), with growing registry data suggesting improved periprocedural outcomes:

A Vascular Quality Initiative (VQI) analysis of 198,166 procedures (2016–2023) reported stroke/death rates of 1.6% for TCAR vs 2.9% for tfCAS (aOR 1.84 for tfCAS vs TCAR; P<0.001). CEA had the lowest rate at 1.3% (aOR 0.83 for CEA vs TCAR; P<0.001).

TCAR was safer than tfCAS regardless of aortic arch type or degree of atherosclerosis.

The ROADSTER-1 and ROADSTER-2 trials demonstrated a combined periprocedural stroke rate of 0.6% and combined stroke/death rate of 1.2% in symptomatic patients undergoing TCAR.

Indications

The aim of CAS is to prevent the adverse sequelae of carotid artery stenosis secondary to atherosclerotic disease, primarily stroke.

Symptomatic Patients

CAS is indicated for symptomatic patients (TIA or nondisabling stroke within the preceding 6 months) with ≥50% carotid stenosis by angiography (or ≥70% by noninvasive imaging), provided the anticipated rate of periprocedural stroke or death is <6%.

CAS may be preferred over CEA in symptomatic patients who are:

Aged <70 years (where CAS and CEA outcomes are comparable)

At high surgical risk for CEA (see below)

With unfavorable neck anatomy for surgery

Revascularization should typically occur within 2 weeks after symptom onset.

Asymptomatic Patients

CAS is indicated for asymptomatic patients with ≥70% stenosis (by validated duplex ultrasound) or ≥80% stenosis (by CTA or MRA), provided the anticipated rate of periprocedural stroke or death is <3%, and the patient has a life expectancy of at least 3–5 years.

The CREST-2 trial demonstrated that CAS plus intensive medical therapy was superior to intensive medical therapy alone for asymptomatic carotid stenosis (4-year stroke or death: 2.8% vs 6.0%; P=0.02). However, the ECST-2 interim results and a pooled meta-analysis did not show a significant benefit of revascularization over optimized medical therapy alone.

High-Risk Features Favoring CAS Over CEA

CAS is particularly considered in patients with at least one anatomic or comorbid risk factor placing them at high risk for adverse events from CEA:

Anatomic Risk Factors:

Contralateral carotid artery occlusion

Contralateral laryngeal nerve palsy

Scarring of the neck post radiation therapy or following neck surgery

Recurrent stenosis after prior carotid endarterectomy

High cervical carotid artery lesions (distal to the second cervical vertebra)

Carotid artery stenosis below the clavicle or proximal (intrathoracic) arterial stenosis

Previous carotid endarterectomy

Contralateral vocal cord paralysis

Open tracheostomy

Comorbid Conditions:

Congestive heart failure (NYHA Class III/IV) and/or known severe left ventricular dysfunction (LVEF ≤30%)

Open-heart surgery needed within 6 weeks

Recent myocardial infarction (>24 hours and <4 weeks)

Unstable angina (CCS class III/IV)

Synchronous severe cardiac and carotid disease requiring open heart surgery and carotid revascularization

Severe pulmonary disease (chronic oxygen therapy, resting PO2 <60 mmHg, baseline hematocrit >50%, FEV1 or DLCO <50% of normal)

Abnormal stress test

Age greater than 80 years (note: age >80 is also associated with higher CAS periprocedural risk)

Carotid Revascularization in Patients Undergoing CABG

Symptomatic Stenosis

CAS (with embolic protection) before or concurrent with CABG is reasonable in patients with >80% stenosis who have experienced ipsilateral retinal or hemispheric cerebral ischemic symptoms within 6 months (Class I, Level C).

Asymptomatic Stenosis

The safety and efficacy of carotid revascularization before or concurrent with myocardial revascularization are not well established (Class IIb, Level C).

Risk Stratification

High-Risk Lesion Characteristics

Evidence of intraluminal thrombus thought to increase the risk of plaque fragmentation and distal embolization

Lesion(s) that may require more than two stents

Very tortuous lesions

Total occlusion of the target vessel

Lesions of the ostium of the common carotid artery

Highly calcified lesions resistant to balloon inflation

Concurrent treatment of bilateral lesions

High-Risk Access Characteristics

Patients with known peripheral vascular, supra-aortic, or internal carotid artery tortuosity that would preclude the use of catheter-based techniques

Type III aortic arch anatomy (strongly associated with increased periprocedural risk with transfemoral CAS)

Patients in whom femoral or brachial access is not possible

High-Risk Patient Characteristics

Patients at low-to-moderate risk for adverse events from carotid endarterectomy (where CEA is generally preferred)

Patients experiencing acute ischemic neurologic stroke or who experienced a stroke within 48 hours

Patients with an intracranial mass lesion (i.e., abscess, tumor, or infection) or aneurysm (>9 mm)

Patients with arteriovenous malformations of the territory of the target carotid artery

Patients with coagulopathies

Patients with poor renal function, who may be at high risk for a reaction to contrast medium

Patients with perforated vessels evidenced by extravasation of contrast media

Patients with aneurysmal dilation immediately proximal or distal to the lesion

Pregnant patients or patients under the age of 18

Age as a Risk Modifier

Age is an important modifier of CAS outcomes. The Cochrane review demonstrated no clear benefit of CEA over CAS in patients aged <70 years, whereas patients aged ≥70 years had significantly better outcomes with CEA. CAS may be preferred in younger symptomatic patients, while CEA may be preferred in older patients.

Stenting (CAS) vs Carotid Endarterectomy (CEA)

Outcomes

A meta-analysis by Sardar et al. (2017) demonstrated that CAS was associated with lower periprocedural myocardial infarction (OR ~0.5) but higher periprocedural stroke (~double) compared to CEA.

Key comparative findings across trials:

Periprocedural stroke: Higher with CAS than CEA (CREST: 4.1% vs 2.3%, P=0.01)

Periprocedural MI: Higher with CEA than CAS (CREST: 2.3% vs 1.1%, P=0.03)

Cranial nerve palsy: Significantly less frequent with CAS (5 vs 51 per 1,000)

Long-term ipsilateral stroke: No significant difference at 10 years (CREST: 6.9% CAS vs 5.6% CEA; HR 0.99)

Restenosis: Moderate (≥50%) restenosis more frequent after CAS; severe (≥70%) restenosis rates similar (5–12% CAS vs 8–10% CEA at 5–10 years). Restenosis after CEA (but not CAS) was associated with increased stroke risk.

Summary table comparing CAS vs CEA recommendations by symptom status and stenosis severity

	Symptomatic Patients		Asymptomatic Patients
	50–69% Stenosis	70–99% Stenosis	70–99% Stenosis
Endarterectomy	Class I	Class I	Class IIa
Level of Evidence	B	A	A
Stenting	Class I	Class I	Class IIb
Level of Evidence	B	B	B

Scenarios Where Carotid Endarterectomy is Preferred

CEA is generally preferred in the setting of:

Age ≥70 years (particularly in symptomatic patients)

Impaired renal function with increased risk of contrast-induced nephropathy

A tortuous, calcified aorta

Complex, eccentric, calcified lesions

Severe aortic arch atherosclerosis

Scenarios Where Carotid Artery Stenting is Preferred

CAS is generally preferred in the setting of:

Neck anatomy unfavorable for arterial surgery (Class IIa, Level B)

High carotid bifurcation where it is technically difficult for surgeons to perform the surgery

Arterial stenosis distal to the second cervical vertebra or proximal (intrathoracic) arterial stenosis

Previous ipsilateral carotid endarterectomy

Contralateral vocal cord paralysis

Open tracheostomy

History of previous radical neck surgery

History of radiation therapy

Age <70 years in symptomatic patients

Procedure

Patient Preparation

Informed consent obtained

Dual antiplatelet therapy (DAPT): Aspirin 325 mg plus clopidogrel 75 mg initiated at least 48 hours prior to the procedure. Alternatives for clopidogrel-intolerant patients include ticagrelor 60–90 mg twice daily or prasugrel 5–10 mg daily.

Pre-procedural statin therapy is reinforced

Local anesthetic administered (general anesthesia is discouraged for transfemoral CAS)

Transfemoral CAS Technique

Preparation of both groins with antiseptic and draping

Puncture into femoral artery and access through short sheath

Guidewire passed through aorta and into the aortic arch

Arch aortogram obtained if not previously performed to confirm suitability to continue

Selective carotid and cerebral angiogram performed

Long access sheath or guide catheter placed after cannulation of common carotid artery (CCA)

Guidewire passed through area of carotid narrowing

Placement of embolic protection device (EPD) above the area of narrowing (distal filter) or proximal flow-reversal device

Pre-dilation angioplasty of carotid narrowing (optional; many operators proceed directly to stent deployment)

Deployment of stent into area of narrowing

Post-stent angioplasty (with caution; balloons >5.0 mm are discouraged)

Removal of protection device, guidewires, and sheath

Aftercare of groin puncture site

Intraprocedural anticoagulation with heparin (target activated clotting time 250–300 seconds)

Transcarotid Artery Revascularization (TCAR) Technique

Direct surgical exposure of the common carotid artery in the neck via a small incision

Arterial sheath inserted directly into the CCA

Establishment of temporary carotid flow reversal via an arteriovenous circuit (CCA to internal jugular vein) for cerebral embolic protection

Stent deployment under flow reversal

Restoration of antegrade flow and closure of the arteriotomy

Embolic Protection Devices

Embolic protection is considered essential during CAS to reduce the risk of distal cerebral embolism:

Distal filter devices:

Capture embolic debris on a filter placed distal to the lesion in the internal carotid artery

Examples: Rx Accunet, Emboshield Nav6, FilterWire EZ, Angioguard, Spider Fx, Gore embolic filter

Proximal flow-reversal/occlusion devices:

Achieve cerebral protection by reversing or arresting flow in the ICA during the procedure

Examples: MoMa device, Gore flow-reversal device

Associated with fewer microembolic signals on transcranial Doppler compared to distal filters

Stent Types

First-generation stents:

Open-cell design (e.g., Acculink, Wallstent, Precise): Greater flexibility and conformability to vessel anatomy but larger free cell area, which may allow plaque prolapse.

Closed-cell design (e.g., Xact): Smaller free cell area providing better plaque coverage but less conformability.

Second-generation (dual-layer/mesh-covered) stents:

Feature an inner mesh layer designed to trap and exclude plaque debris from the vessel lumen, reducing distal embolization.

Examples: CGuard (InspireMD), Roadsaver/Casper (Terumo/MicroVention).

A systematic review and meta-analysis of 68,422 patients demonstrated significantly lower 30-day death/stroke/MI rates with second-generation stents compared to first-generation stents (1.30% vs 4.11%; P<0.01).

A patient-based meta-analysis of 556 patients treated with dual-layer stents reported a 30-day stroke rate of 1.25% and 30-day mortality of 0.17%.

Complications

Periprocedural Stroke

Periprocedural stroke is the most significant complication of CAS. In the CREST trial, the periprocedural stroke rate was 4.1% for CAS vs 2.3% for CEA (P=0.01). The risk is higher in patients aged ≥70 years, those with severe aortic arch atherosclerosis, and those with tortuous vascular anatomy.

Cerebral Hyperperfusion Syndrome

Cerebral hyperperfusion syndrome (CHS) is a potentially life-threatening complication characterized by ipsilateral headache, seizures, focal neurologic deficits, and/or intracerebral hemorrhage occurring after restoration of normal carotid blood flow.

Pooled CHS risk after CAS: 4.6% (meta-analysis).

VQI data: CHS incidence 0.15% CEA, 0.18% TCAR, 0.53% tfCAS.

Risk factors include: impaired cerebrovascular reserve, contralateral carotid stenosis ≥70%, and post-procedure hypertension.

Strict blood pressure control (systolic <140 mmHg) in the periprocedural period is essential for prevention.

Hemodynamic Complications

Bradycardia and hypotension due to baroreflex stimulation during stent deployment at the carotid sinus occur in 5–10% of CAS cases. These are usually transient but may require atropine or temporary pacing.

Sustained hemodynamic depression (>1 hour) is more common in patients with contralateral carotid stenosis and calcified lesions.

Other Complications

Myocardial infarction: ~1% (lower than with CEA)

Arterial dissection or thrombosis: <1%

Cranial nerve palsy: Rare with CAS (5 per 1,000 vs 51 per 1,000 with CEA)

Access site complications (hematoma, pseudoaneurysm, arteriovenous fistula)

Contrast-induced nephropathy

In-stent restenosis (see below)

Post-Procedural Care and Long-Term Management

Immediate Post-Procedural Care

Neurologic monitoring for at least 24 hours post-procedure

Strict blood pressure control: systolic blood pressure <140 mmHg to reduce the risk of cerebral hyperperfusion syndrome

Monitoring for hemodynamic instability (bradycardia, hypotension)

Groin/access site assessment

Antithrombotic Therapy

Dual antiplatelet therapy (DAPT): Aspirin 325 mg plus clopidogrel 75 mg daily for a minimum of 30 days post-procedure

After 30 days: Aspirin (81–325 mg) continued indefinitely

Alternatives for clopidogrel-intolerant patients: ticagrelor 60–90 mg twice daily or prasugrel 5–10 mg daily

Medical Therapy Optimization

Intensive medical therapy is a critical component of long-term management regardless of revascularization status:

Statin therapy: High-intensity statin (e.g., atorvastatin 40–80 mg or rosuvastatin 20–40 mg) with target LDL cholesterol <70 mg/dL

Antihypertensive therapy: Target blood pressure <130/80 mmHg

Diabetes mellitus management: Target HbA1c <7%

Smoking cessation

Lifestyle modifications: Exercise, Mediterranean diet, weight management

Surveillance for Restenosis

Duplex ultrasound surveillance is recommended post-CAS to monitor for in-stent restenosis.

Moderate (≥50%) restenosis is more frequent after CAS than CEA; however, severe (≥70%) restenosis rates are similar (5–12% CAS vs 8–10% CEA at 5–10 years).

Restenosis after CEA (but not CAS) was associated with increased stroke risk in the ICSS secondary analysis.

Annual stroke risk with severe in-stent restenosis is approximately 1%.

Suggested surveillance schedule: duplex ultrasound at 1 month, 6 months, and 12 months post-procedure, then annually thereafter.

Treatment Algorithm

The following algorithm summarizes the approach to management of carotid stenosis:

Step 1: Determine Symptom Status

Symptomatic: TIA or nondisabling stroke within the preceding 6 months

Asymptomatic: Incidental finding on imaging

Step 2: Confirm Degree of Stenosis

Noninvasive imaging: Duplex ultrasound, CTA, or MRA

Catheter angiography if noninvasive results are discordant

Step 3: Assess Candidacy for Revascularization

Clinical Scenario	Recommended Approach
Symptomatic, ≥50% stenosis (angiography) or ≥70% (noninvasive), standard surgical risk	CEA preferred (Class I); CAS acceptable alternative especially if age <70 years
Symptomatic, ≥50% stenosis, high surgical risk for CEA	CAS with EPD (Class I)
Asymptomatic, ≥70% stenosis (duplex) or ≥80% (CTA/MRA), life expectancy ≥3–5 years	CEA or CAS with intensive medical therapy; benefit of revascularization over medical therapy alone remains debated
Asymptomatic, <70% stenosis	Intensive medical therapy alone
Symptomatic, <50% stenosis	Medical therapy alone

Step 4: Choose Revascularization Modality

CEA preferred: Age ≥70 years, severe aortic arch disease, tortuous anatomy, calcified lesions, impaired renal function

CAS (transfemoral) preferred: Hostile neck (prior surgery, radiation, high bifurcation), contralateral vocal cord paralysis, age <70 years

TCAR preferred: When CAS is indicated but unfavorable aortic arch anatomy (Type III arch, severe arch atherosclerosis) precludes safe transfemoral access

Step 5: Optimize Medical Therapy

All patients should receive intensive medical therapy regardless of revascularization decision: high-intensity statin, antiplatelet therapy, blood pressure control, diabetes management, and smoking cessation.

External links

• Carotid Revsacularization Endarterectomy versus Stenting Trial (CREST)