Description
Carotid artery angioplasty with stenting is a treatment for carotid stenosis that is intended to prevent a future stroke. It is an alternative to medical therapy and a less-invasive alternative to carotid endarterectomy (CEA).

Summary of Evidence
For individuals who have carotid artery stenosis who receive carotid artery stenting (CAS), the evidence includes randomized controlled trials and systematic reviews of these trials. Relevant outcomes are overall survival, morbid events, and treatment-related mortality and morbidity. A substantial body of randomized controlled trial evidence has compared outcomes of CAS with CEA for symptomatic and asymptomatic patients with carotid stenosis. The evidence does not support the use of CAS in carotid artery disease for the average-risk patient because early adverse events are higher with CAS and long-term outcomes are similar between the 2 procedures. Data from randomized controlled trials and large database studies have established that the risk of death or stroke with CAS exceeds the threshold considered acceptable to indicate overall benefit from the procedure. Therefore, for patients with carotid stenosis who are suitable candidates for CEA, CAS does not improve health outcomes. The evidence is sufficient to determine that the technology is unlikely to improve the net health outcome.

Additional Information
Based on limited data, clinical input, a chain of evidence and unmet medical need, CAS may be considered a reasonable treatment option in recently symptomatic patients when CEA cannot be performed due to anatomic reasons. For this population, CAS may be considered medically necessary. It is considered investigational for all other indications, including carotid artery dissection.

2009 Input
In response to requests, input was received from 4 physician specialty societies (6 reviewers) and 4 academic medical centers while this policy was under review in 2009. (Also, an unsolicited response from a specialty society was received.) Input strongly supported the use of carotid artery stenting (CAS) in recently symptomatic patients where surgical carotid endarterectomy cannot be performed due to anatomic reasons, although acknowledging the limited evidence about this subgroup. The lack of alternative treatments for recently symptomatic patients and the established increased risk of stroke were factors supporting this opinion.

Background
Combined with optimal medical management, carotid angioplasty with or without stenting has been evaluated as an alternative to carotid endarterectomy (CEA). Carotid artery stenting (CAS) involves the introduction of coaxial systems of catheters, microcatheters, balloons, and other devices. The procedure is most often performed through the femoral artery, but a transcervical approach can also be used to avoid traversing the aortic arch. The procedure typically takes 20 to 40 minutes. Interventionalists almost uniformly use an embolic protection device (EPD) designed to reduce the risk of stroke caused by thromboembolic material dislodged during CAS. EPDs can be deployed proximally (with flow reversal) or distally (using a filter). Carotid angioplasty rarely is performed without stent placement.

Proposed advantages of CAS over CEA include:

• General anesthesia is not used (although CEA can be performed under local/regional anesthesia).
• Cranial nerve palsies are infrequent sequelae (although almost all following CEA resolve over time).
• Simultaneous procedures may be performed on the coronary and carotid arteries.

Regulatory Status
A number of carotid artery stents and EPDs have been approved by the U.S. Food and Drug Administration (FDA) through the premarket approval (PMA) or the 510(k) process. Table 1 lists the original PMAs with product code NIM and Table 2 lists 510(k) approvals with product code NTE.

Table 1. FDA Premarket Approvals for Carotid Artery Stents and Embolic Protection Devices  

Manufacturer	Device	PMA	PMA Date
Cordis Corp.	Cordis Precise Nitinol Stent System	P030047	Sept 2006
Abbott Vascular	Acculink Carotid Stent System and Rx Acculink Carotid Stent System	P040012	Aug 2004
Abbott Vascular	XACT Carotid Stent System	P040038	Sep 2005
Boston Scientific Corp.	Carotid Wallstent Monorail Endoprosthesis	P050019	Oct 2008
Boston Scientific Corp.	Endotex Nexstent Carotid Stent and Delivery System and Endotex Carotid Stent and Monorail Delivery System	P050025	Oct 2006
Medtronic Vascular	jProtege GPS and Protege Rx Carotid Stent Systems	P060001	Jan 2007
Medtronic Vascular	Exponent Self-Expanding Carotid Stent System with Over-the-Wire or Rapid-Exchange Delivery System	P070012	Oct 2007
Silk Road Medical Inc.	Enroute Transcarotid Stent System	P140026	May 2015
	Enroute Transcarotid Stent System	P140026 S016	Apr 2022
W. L Gore & Associates Inc. Gore Carotid Stent	Gore Carotid Stent	P180010	Nov 2018

FDA: Food and Drug Administration; PMA: Premarket approval.

Table 2. FDA 510(k) Carotid Artery Stents and Embolic Protection Devices

Manufacturer	Stents and Devices	510(k) Number	PMA/510(k) Date
Guidant, now Abbott Vascular	Accunet and RX AccunetEmbolic protection system	K042218	Aug 2004
Guidant, now Abbott Vascular	Rx Accunet 2 Embolic Protection System	K042908	Nov 2004
Guidant, now Abbott Vascular	Rx Accunet Embolic Protection System	K052165	Aug 2005
Abbott Vascular	Emboshield® embolic protection system	K052454	Sep 2005
Cordis Corp.	AngioGuardä XP and RX emboli capture guidewire systems	K062531	Sep 2006
Boston Scientific	FilterWire EZ™ embolic protection system	K063313	Dec 2006
EV3 Inc	Spiderx	K052659	Feb 2007
EV3 Inc	Spidefx	K063204	Nov 2007
GORE	GORE® Flow Reversal System	K083300	Feb 2009
GORE	GORE® Embolic Filter	K103500	May 2011
Medtronic/Invatec	Mo.Ma® Ultra Proximal Cerebral Protection Device	K092177	Oct 2009
Silk Road Medical	ENROUTE™ Transcarotid Stent System and ENROUTE Transcarotid Neuroprotection System	K143072	Feb 2015
Gardia Medical	Wirion	K143570	Jun 2015
Abbott Vascular	Rx Accunet Embolic Protection System	K153086	Nov 2015
Silk Road Medical, Inc.	Enroute Transcarotid Neuroprotection System	K153485	Mar 2016
Gardia Medical Ltd.	Wirion	K180023	Mar 2018
Contego Medical LLC	Paladin Carotid Post-Dilation Balloon System With Integrated Embolic Protection (Paladin System)	K181128	Sep 2018
Contego Medical LLC	Vanguard lep Peripheral Balloon Angioplasty System With Integrated Embolic Protection	K181529	Dec 2018
Abbott Vascular	Emboshield Nav6 Embolic Protection System, Barewire Filter Delivery Wires	K191173	Jul 2019
Cardiovascular Systems	Wirion	K200198	Mar 2020
Cardiovascular Systems	Wirion Embolic Protection System	K210282	Mar 2021
Cordis Corporation	Angioguard Xp Emboli Capture Guidewire, Angioguard Rx Emboli Capture Guidewire	K220654	Apr 2022
Contego Medical Inc.	Paladin Carotid Post-Dilation Balloon System With Integrated Embolic Protection	K221339	Jun 2022
Silk Road Medical	Enroute® Transcarotid Neuroprotection System	K230402	Apr 2023

FDA: Food and Drug Administration; PMA: premarket approval.

Each FDA-approved carotid stent is indicated for combined use with an EPD to reduce risk of stroke in patients considered at increased risk for periprocedural complications from CEA who are symptomatic with greater than 50% stenosis, or asymptomatic with greater than 80% stenosis with the degree of stenosis assessed by ultrasound or angiogram, with computed tomography angiography also used. Patients are considered at increased risk for complications during CEA if affected by any item from a list of anatomic features and comorbid conditions included in each stent system’s Information for Prescribers.

The RX Acculinkä Carotid Stent System is also approved for use in conventional risk patients (not considered at increased risk for complications during CEA) with symptoms and 70% or more stenosis by ultrasound or 50% or more stenosis by angiogram, and asymptomatic patients with 70% or more stenosis by ultrasound or 60% or more stenosis by angiogram.

The FDA-approved stents and EPDs differ in the deployment methods used once they reach the target lesion, with the rapid exchange devices designed for more rapid stent and filter expansion. The FDA has mandated postmarketing studies for EPDs, including longer follow-up for patients already reported to the FDA and additional registry studies, primarily to compare outcomes as a function of clinician training and facility experience. Each manufacturer’s system is available in various configurations (e.g., straight or tapered) and sizes (diameters and lengths) to match the vessel lumen that will receive the stent.

In 2015, the ENROUTE™ Transcarotid Neuroprotection System was cleared for marketing by the FDA through the 510(k) process. ENROUTE is a flow reversal device designed to be placed via direct carotid access. In April 2022, the ENROUTE^® Transcarotid Stent System received expanded approval for use in the treatment of individuals at standard risk of complications from CEA. For those with neurological symptoms, criteria include 70% or more stenosis by ultrasound or 50% or more stenosis by angiogram. For asymptomatic individuals, criteria include 70% or more stenosis by ultrasound or 60% or more stenosis by angiogram. The carotid bifurcation location must be a minimum of 5 cm above the clavicle to allow for the placement of the ENROUTE Transcarotid Neuroprotection System.

FDA product codes: NIM (stents) and NTE (EPDs).

Policy:
Carotid angioplasty with associated stenting and embolic protection may be considered MEDICALLY NECESSARY in patients with all of the above:

• 50% – 99% stenosis (NASCET measurement)AND
• Symptoms of focal cerebral ischemia (transient ischemic attack or monocular blindness) in previous 120 days, symptom duration less than 24 hours, or nondisabling stroke AND
• Anatomic contraindication for carotid endarterectomy (such as prior radiation treatment or neck surgery, lesions surgically inaccessible, spinal immobility, or tracheostomy).

Carotid angioplasty with or without associated stenting and embolic protection is considered investigational and/or unproven and therefore NOT MEDICALLY NECESSARY for all other indications, including but not limited to, patients with carotid stenosis who are suitable candidates for CEA and patients with carotid artery dissection.

Policy Guidelines
The intent of the second investigational policy statement is that carotid angioplasty with embolic protection but without stenting is investigational. There may be unique situations where the original intent of surgery was to perform carotid angioplasty with stenting and embolic protection, but anatomic or other considerations prohibited placement of the stent.

Please see the Codes table for details.

Benefit Application
BlueCard^®/National Account Issues
State or federal mandates (e.g., FEP) may dictate that all devices approved by the U.S. Food and Drug Administration (FDA) may not be considered investigational, and thus these devices may be assessed only on the basis of their medical necessity.

Rationale
Evidence reviews assess the clinical evidence to determine whether the use of a technology improves the net health outcome. Broadly defined, health outcomes are the length of life, quality of life, and ability to function including benefits and harms. Every clinical condition has specific outcomes that are important to patients and managing the course of that condition. Validated outcome measures are necessary to ascertain whether a condition improves or worsens; and whether the magnitude of that change is clinically significant. The net health outcome is a balance of benefits and harms.

To assess whether the evidence is sufficient to draw conclusions about the net health outcome of technology, 2 domains are examined: the relevance, and quality and credibility. To be relevant, studies must represent 1 or more intended clinical use of the technology in the intended population and compare an effective and appropriate alternative at a comparable intensity. For some conditions, the alternative will be supportive care or surveillance. The quality and credibility of the evidence depend on study design and conduct, minimizing bias and confounding that can generate incorrect findings. The randomized controlled trial (RCT) is preferred to assess efficacy; however, in some circumstances, nonrandomized studies may be adequate. Randomized controlled trials are rarely large enough or long enough to capture less common adverse events and long-term effects. Other types of studies can be used for these purposes and to assess generalizability to broader clinical populations and settings of clinical practice.

Promotion of greater diversity and inclusion in clinical research of historically marginalized groups (e.g., people of color [African-American, Asian, Black, Latino and Native American]; LGBTQIA (lesbian, gay, bisexual, transgender, queer, intersex, asexual); women; and people with disabilities [physical and invisible]) allows policy populations to be more reflective of and findings more applicable to our diverse members. While we also strive to use inclusive language related to these groups in our policies, use of gender-specific nouns (e.g., women, men, sisters, etc.) will continue when reflective of language used in publications describing study populations.

Clinical Context and Therapy Purpose
The purpose of carotid artery stenting (CAS) is to provide a treatment option for carotid artery stenosis that is an alternative to medical therapy and a less-invasive alternative to carotid endarterectomy (CEA).

The following PICO was used to select literature to inform this review.

Populations
The relevant population of interest is individuals with coronary artery stenosis.

Interventions
The therapy being considered is CAS. Revascularization with CAS can be accomplished via transfemoral, transradial, or transcarotid endovascular approaches.

Comparators
The comparator of interest is CEA.

Outcomes
The general outcomes of interest are overall survival, morbid events, treatment-related mortality, and treatment-related morbidity.

Study Selection Criteria
Methodologically credible studies were selected using the following principles:

• To assess efficacy outcomes, comparative controlled prospective trials were sought, with a preference for RCTs and systematic reviews.
• In the absence of such trials, comparative observational studies were sought, with a preference for prospective studies.
• To assess long-term outcomes and adverse events, single-arm studies that capture longer periods of follow-up and/or larger populations were sought.
• Studies with duplicative or overlapping populations were excluded.

Review of Evidence
Risk-Benefit Ratio of Invasive Carotid Procedures
Endovascular CAS and surgical CEA for carotid artery disease trade procedure-related harms of stroke and death for the benefit of reduced stroke risk over subsequent years; the balance determines whether either intervention will result in a net clinical benefit. That balance has been scrutinized for CEA but not for CAS; accordingly, results from trials of CEA must be extrapolated to assess outcomes for CAS.

Randomized Controlled Trials
A series of landmark clinical trials from the late 1980s through the 1990s compared the benefits and harms of CEA with best medical therapies then available in symptomatic and asymptomatic individuals with carotid artery stenosis.^{1,2,3,4,5,6,7} Those trial results defined the magnitude of risk reduction for stroke and the periprocedural stroke and death rates for 30 days, which must be offset to achieve a net clinical benefit (benefit outweighing harm), less than 3% for asymptomatic (> 60% stenosis), and less than 6% for symptomatic patients (50% – 69% or 70% – 99% stenosis). Furthermore, because periprocedural harms are immediate, but benefit accrues over time, a net clinical benefit is obtained only for those patients surviving long enough to counterbalance the immediate harms. The necessary life expectancy defined by the trial duration needed to demonstrate benefit is summarized in Table 3.

Table 3. Acceptable Periprocedural Death or Stroke Rate in Clinical Trials of CEA

Symptoms	Stenosis, %	Acceptable Periprocedural Death/Stroke Rate, %	Anticipated Life Expectancy, y
No	60 – 99	< 3	5
Yes	50 – 69	< 6	5
	70 – 99	< 6	2

CEA: carotid endarterectomy.

As an example of the fine line between benefit and harm, Arazi et al. (2008)8, performed a decision analysis of benefit for patients with asymptomatic stenosis using a base case derived from the Asymptomatic Carotid Surgery Trial (periprocedural death/stroke rate, 1.8%).7, Over a 5-year time horizon, CEA provided 4 days of stroke-free survival and net harm when periprocedural death or disabling stroke rates exceeded 2.1%.

Since the landmark trials, there has been considerable improvement in medical care resulting in a substantial decline in stroke rates among patients with asymptomatic carotid disease.^9,10 Current medical therapies such as aggressive lipid-lowering medications, were inconsistently used in the landmark trials. Also, surgeons in contemporary clinical trials have achieved CEA periprocedural death and stroke rates lower than those in the pivotal trials used to establish the benchmarks. For example, in the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST), the death or stroke rate for symptomatic patients was 3.2%, and for asymptomatic patients was 1.4%.11, Accordingly, the benchmarks established decades ago may no longer be appropriate. A recent consensus document by De Rango et al. (2013) has suggested benchmarks of 2.0% for asymptomatic and 4.0% for symptomatic individuals.¹²

Excluded from landmark CEA trials were patients with significant comorbidities judged likely to cause death within 5 years that might also increase periprocedural and anesthetic risk for complications. Therefore, CAS has appeal as a treatment option for patients with potentially higher periprocedural risk due to medical (e.g., severe cardiac dysfunction, requirement for combined coronary and carotid revascularization, severe renal or pulmonary dysfunction, and other characteristics associated with increased surgical risk) or anatomic reasons (e.g., surgically inaccessible stenosis, prior radiation, prior neck surgery, spinal immobility, prior laryngeal nerve palsy, contralateral occlusion, prior ipsilateral CEA, restenosis after CEA).

Although the general anesthetic risk is considered a potential reason to use CAS, CEA can be safely performed under local or regional anesthesia,¹³ as confirmed in the 95-center General Anesthesia versus Local Anesthesia (GALA) trial.¹⁴ The GALA trial investigators randomized 3,526 patients undergoing CEA to general or local anesthesia and found no difference in 30-day death, stroke, or myocardial infarction (MI) rates based on anesthetic approach (relative risk [RR], 0.94; 95% confidence interval [CI], 0.70 to 1.3).¹⁴

Randomized Controlled Trials of Carotid Artery Stenting Versus Carotid Endarterectomy
SAPPHIRE Trial
The first major RCT comparing CAS with CEA was the Stenting and Angioplasty, with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) trial reported by Yadav et al. (2004).¹⁵ The relevant conclusions are summarized below:

• For patients with symptomatic stenosis at increased risk for periprocedural complications from CEA (n = 96), the sample size was small, resulting in wide CIs for estimated effects; differences between arms in 30-day and 1-year outcomes were not statistically significant.
• For patients with asymptomatic stenosis at increased risk for periprocedural complications from CEA (n = 238), differences in 30-day outcomes also had wide CIs and were not statistically significant.
• The study closed early due to slow recruitment as nonrandomized stent registries were established, resulting in fewer study patients than planned, which compromised the evaluation of noninferiority.
• Variance in differential complication rates for the 2 treatments across sites might have influenced results, because 5 of 34 sites contributed 64% of randomized patients, and data were unavailable for comparison.
• Direct comparative evidence was lacking for optimal medical management alone as an alternative to adding CAS with an embolic protection device (EPD) or CEA for patients with increased risk of surgical complications.

Long-term follow-up of SAPPHIRE was reported at 3 years.^16,17 For asymptomatic and symptomatic patients combined, ipsilateral strokes from day 31 to day 1,080 were observed in 4.4% of patients undergoing CAS and in 3.6% with CEA (estimated from a digitized figure). Cumulative 3-year repeat target vessel revascularization (a proxy for restenosis) was more common after CEA but the difference was not statistically significant (7.1% vs. 3.0%; p = .26).

SPACE Trial
Ringleb et al. (2006) published results from the Stent-supported Percutaneous Angioplasty of the Carotid Artery versus Endarterectomy (SPACE) trial. This trial randomized 1,200 patients within 180 days of neurologic symptoms, transient ischemic attack, or moderate (nondisabling) stroke, and with 50% or more stenosis of the ipsilateral carotid artery to CAS (n = 605) with or without EPD (73% of procedures performed without) or to CEA (n = 595).¹⁸ The analysis (N = 1,183) failed to conclude that CAS was noninferior to CEA by a margin of 2.5% for the primary outcome of ipsilateral ischemic stroke or death by 30 days after randomization. Periprocedural (30-day) event rates were 6.8% for the CAS group and 6.3% for the CEA group. The absolute between-group difference favored CEA and was 0.5% (90% CI, -1.9 to 2.9 ) by intention-to-treat analysis and 1.3% (90% CI, -1.1 to 3.8 ) in the per-protocol analysis.

Editorialists pointed to some methodologic issues raised with the SPACE trial, including the high rate of rejection for potential participating collaborators (» 25%, based on their prior outcomes records, but review criteria were not reported), and the lack of a requirement to use an EPD with CAS (although 30-day event rates were 7.3% with vs. 6.7% without EPD).^19,20

Long-term follow-up of the SPACE trial was reported at 2 years.17, Approximate annual ipsilateral stroke rates from day 31 through longest follow-up for CAS and CEA were 0.4% in each group. Following the periprocedural period (i.e., 31 days to longest follow-up), stroke risk reduction in symptomatic patients not selected based on medical or anatomic comorbidities was similar for CAS and CEA. Recurrent stenosis greater than 70% was more frequent at 2 years with CAS (10.7%) than with CEA (4.6%; p = .001).

EVA-3S Trial
The Endarterectomy Versus Stenting in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) trial was a noninferiority comparison of CAS (with EPD in 92% of patients) to CEA in symptomatic patients at average risk for complications from CEA with 60% or more stenosis of the ipsilateral carotid artery.²¹ The trial was terminated prematurely (N = 527 enrolled; original target N = 872), based on interim analysis of 30-day outcomes. The incidence of any stroke or death through 30 days was 3.9% (95% CI, 2.0 to 7.2 ) after CEA and 9.6% (95% CI, 6.4 to 14 ) after CAS (RR, 2.5 ; 95% CI, 1.2 to 5.1; p = .01).

Over a mean 2.1 years of follow-up, restenosis (≥ 50%) was more frequent following CAS (12.5%) than CEA (5.0%).²² Long-term follow-up from the EVA-3S trial was reported at 4 years.²³ Approximate annual ipsilateral stroke rates from day 31 through longest follow-up for CAS and CEA, respectively, were 1.1% and 0.9%. These results supported a conclusion that following the periprocedural period (i.e., 31 days to longest follow-up), stroke risk reduction in symptomatic patients not selected based on medical or anatomic comorbidities was similar for CAS and CEA.

Editorialists criticized the EVA-3S trial for recommending but not requiring antiplatelet premedication (3 days of aspirin plus ticlopidine or clopidogrel) and for not requiring interventionalists to be adequately experienced with the specific stent, and EPDs used to treat trial subjects.^19,20 Participating interventionalists were required to have completed 12 or more CAS procedures compared with 25 or more CEAs for vascular surgeons. The EVA-3S trial also permitted the use of 5 different stents and 7 different EPDs but required only 2 prior procedures with a new device before an investigator could use that device on a patient randomized to CAS.

Mas et al. (2014) published long-term follow-up (median, 7.2 years) from the EVA-3S trial.²⁴ Complete follow-up until death or the final telephone interview was obtained in 493 (94%) of the 527 patients. At the 5-year follow-up, the main composite endpoint (ipsilateral stroke after randomization or procedural stroke or death) occurred in 29 (11%) of 265 subjects in the CAS group and 16 (6.1%) of 262 subjects in the CEA group (5-year absolute risk reduction, 4.7%). The hazard ratio (HR) for CAS versus CEA was 1.85 (95% CI, 1.0 to 3.40; p = .04). At the 10-year follow-up, the HR for the main composite endpoint for CAS versus CEA was 1.70 (95% CI, 0.95 to 3.06; p = .07).

International Carotid Stenting Study
The International Carotid Stenting Study (ICSS) enrolled 1,713 symptomatic patients at 50 academic medical centers across Europe, Australia, New Zealand, and Canada between May 2001 and October 2008.²⁵ Embolic protection devices were recommended but not required (used in 72% of procedures), and a number of different stents and EPD types were used. Based on plausible event rates, a target study sample size of 1,500 was estimated to be able to define a between-group difference less than 3.3% in disabling stroke or death and a 3.0% difference in 30-day stroke, death, or MI. Only interim 30- and 120-day results were included in the initial report. From a per-protocol analysis, the 7.1% periprocedural death or stroke death rates accompanying CAS both exceeded the rate established to provide a net clinical benefit and was more than twice that following CEA (3.4%). In a subgroup analysis of 231 ICSS participants, new ischemic brain lesions were approximately 3-fold more frequent following CAS, and protective devices did not appear to mitigate their occurrence.²⁶ Interim results were consistent with the accompanying editorialist’s conclusion that “routine stenting in symptomatic patients must now be difficult to justify ….”²⁷

Bonati et al. (2015) published longer-term follow-up results from ICSS.²⁸ The cumulative 5-year risk of fatal or disabling stroke did not differ significantly between the CAS (6.4%) and the CEA groups (6.5%; HR, 1.06; 95% CI, 0.72 to 1.57 ; p = .77). However, the 5-year cumulative risk of any stroke was higher in the CAS group (15.2%) than in the CEA group (9.45%; HR, 1.71 ; 95% CI, 1.28 to 2.3; p < .001). The authors noted that the difference between the CEA and CAS groups in stroke risk after the procedural period was mainly attributable to strokes occurring in the contralateral carotid or vertebrobasilar territory in the CAS group. Functional outcomes, measured by modified Rankin Scale scores, did not differ significantly between groups.

Altinbas et al. (2014) reported that periprocedural rates of hemodynamic instability in the ICSS differed between CEA and CAS groups.²⁹ Hemodynamic depression occurred more commonly in CAS patients (13.8% vs. 7.2%; RR, 1.9 ; 95% CI, 1.4 to 2.6; p < .000), while hypertension requiring treatment occurred less commonly in CAS patients (RR, 0.2; 95% CI, 0.1 to 0.4; p < .000). Hemodynamic instability was not associated with the ICSS study’s primary composite outcome.

Featherstone et al. (2016) published a health technology assessment on ICSS funded by the National Institute for Health Research.³⁰ The assessment reviewed the data presented above, concluding that "the functional outcome after stenting is similar to endarterectomy, but stenting is associated with a small increase in the risk of nondisabling stroke. The choice between stenting and endarterectomy should take into account the procedural risks related to individual patient characteristics."

CREST Trial
The Carotid Revascularization Endarterectomy Versus Stenting (CREST) Trial was conducted between December 2000 and July 2008, and enrolled 2,522 patients at 117 centers across the U.S. and Canada.¹¹ Of 427 interventionalists who applied to participate in CREST, only 224 (52%) were approved.³¹ Inclusion was initially restricted to recently symptomatic patients. Due to slow enrollment, the protocol was amended to include asymptomatic patients. A protocol amendment in March 2004 excluded further enrollment of patients 80 years and older due to poor outcomes. Of the 1,271 patients randomized to CAS, 65 underwent CEA and 54 underwent neither procedure; of the 1,251 patients randomized to CEA, 13 underwent CAS and 44 underwent neither procedure. Twenty patients were excluded from 1 site due to reported data fabrication. A sample size of 2,500 was targeted to detect a 46% reduction in the HR for the primary endpoint of any stroke, MI, or death during the periprocedural period or ipsilateral stroke within 4 years after randomization.

In the entire sample (symptomatic and asymptomatic patients), investigators reported no difference between CAS and CEA for the primary outcome. Stroke was more frequent following CAS; MI was more frequent after CEA. The periprocedural MI rate after CEA (2.3%) was considerably higher in CREST than any comparable trial (e.g., in EVA-3S, 0.8%; in SPACE, 0%; and in ICSS, 0.6%). This might be attributable to a somewhat higher prevalence of coronary artery disease among participants and routine cardiac enzyme assays, but the relative difference was large. Periprocedural CAS death or stroke rates were the lowest reported in any trial. Although participating interventionalists performing CAS were highly selected, periprocedural death or stroke rates following CAS exceeded those for CEA: in symptomatic patients, 5.6% vs. 2.4%, respectively (the lowest rate for CAS reported in any trial); and in asymptomatic patients, 2.6% vs. 1.4%, respectively.32, The RR for periprocedural death or stroke in the symptomatic group was 1.89 (95% CI, 1.11 to 3.21 and in the asymptomatic group, it was 1.85 (95% CI, 0.79 to 4.34 ). The trial had limited power to detect a difference between procedures in the asymptomatic group. In CREST, 2-year restenosis (> 70%) or reocclusion rates were similar following CEA (6.3%) and CAS (6.0%); 2-year restenosis alone was 5.8% with either procedure.³³

Brott et al. (2016) reported on long-term follow-up from the CREST trial. There were no significant differences in the primary composite outcome (any periprocedural stroke, MI, death, or postprocedural ipsilateral stroke) between the CEA (9.9%) and CAS (11.8%; HR, 1.10 ) groups when followed up to 10 years.³⁴ The second primary endpoint (postprocedural ipsilateral stroke rates) also did not differ significantly between CEA (5.6%) and CAS (6.9%; HR, 0.99).

Interventionalists in CREST were the most carefully selected in any trial, and the lack of similar selection criteria has been a critique of the other trials.³⁵ Analyses of CAS in Medicare patients between 2005 and 2007 found that few CAS operators had the experience of CREST investigators.³⁶ Among the 11,846 procedures with documented operator experience, 68% were performed by operators having performed fewer than 12 procedures.

In a follow-up analysis of CREST data, Gonzales et al. (2014) reported no differences in efficacy and safety outcomes for subjects based on receiving treatment in high-, medium-, or low-volume centers.³⁷

In 2022, Meschia et al. published a post hoc analysis of 826 asymptomatic patients enrolled in CREST with no stroke symptoms at baseline and with at least 1 completed follow-up Questionnaire for Verifying Stroke-free Status (QVSS).³⁸ The HR for adjudicated stroke with CAS compared to CEA in this analysis was nonsignificant at 1.02 (95% CI, 0.57 to 1.85). However, significant treatment differences for CAS versus CEA were detected for the outcome of stroke symptoms (HR, 1.54; 95% CI, 1.15 to 2.08) and the composite outcome of adjudicated stroke or stroke symptoms (HR, 1.38; 95% CI, 1.04 to 1.83). The authors concluded that inclusion of stroke symptoms to broaden the outcome of stroke prevention trials should be considered to permit sufficiently powered analyses in low-risk populations.

Asymptomatic Carotid Trial
The Asymptomatic Carotid Trial was a noninferiority trial reported by Rosenfield et al. (2016) who compared CAS with CEA in asymptomatic individuals, not at high-risk for surgical complications.³⁹ Enrollment began in 2005, with a target of 1,658 participants, but the trial was halted in 2013 at 1453 participants because of slow enrollment. The primary composite endpoint (death, stroke, or MI within 30 days or ipsilateral stroke within 1 year) was met by 3.8% of CAS and 3.4% of CEA patients, while the cumulative 5-year rate of stroke-free survival was 93.1% with CAS and 94.7% with CEA (p = .44). This trial did not answer how best to treat asymptomatic patients because it did not include a medical therapy arm. Patients treated with current best medical therapy might have had an ipsilateral stroke rate of only 0.5% to 1% per year.⁴⁰

Asymptomatic Carotid Trial 2
The second asymptomatic carotid surgery trial (ACST-2) was a multicenter RCT comparing CAS and CEA in 3625 asymptomatic patients with severe carotid stenosis.⁴¹ There was no significant difference between groups in the composite of death, MI, or stroke with CAS or CEA (3.9% vs. 3.2%; p = .26) within 30 days of the procedure. Five-year non-procedure related stroke was also similar between groups (5.3% with CAS vs. 4.5% with CEA; RR, 1.6 ; 95% CI, 0.86 to 1.57; p = .33). The authors considered the long-term outcomes of these procedures to be similar with uncommon serious complications.

Additional Randomized Controlled Trials
Several other smaller trials have compared CEA with CAS. Li et al. (2014) published a trial that randomized 130 subjects at high-risk of stroke due to angiographically confirmed carotid stenosis (≥ 50%) to CEA (n = 65) or CAS (n = 65).⁴² The authors reported a 3-month postoperative risk of mortality of 1.5% with CAS compared with 9.2% with CEA. However, “existence of complete follow-up data” was an inclusion criterion, and insufficient details were provided about enrollment and randomization procedures to permit conclusions about the trial.

Kuliha et al. (2015) published results of an RCT that allocated 150 subjects with at least 70% internal carotid artery stenosis to CEA (n = 73) or CAS (n = 77).⁴³ New infarctions on magnetic resonance imaging were found more frequently after CAS (49% vs. 25%; p = .002).

Reiff et al. (2019) published 1-year interim results of the Stent-supported Percutaneous Angioplasty of the Carotid Artery versus Endarterectomy 2 (SPACE-2) RCT.⁴⁴ The SPACE-2 RCT was originally planned to compare best medical treatment (BMT) to CEA plus BMT or CAS plus BMT in 3550 patients with high-grade asymptomatic extracranial carotid artery stenosis. However, because patient recruitment was slow, the RCT was amended in 2013 to become 2 parallel randomized studies (BMT alone vs. CEA plus BMT, and BMT alone vs. CAS plus BMT). After recruitment continued to be slow, SPACE-2 was ultimately stopped early in 2016 after only 513 patients were randomized. Although the interim analysis did not find significant differences between CEA and CAS in 1-year rates of stroke or all-cause mortality, SPACE-2 authors noted that it is insufficiently powered to detect such differences. Reiff et al. (2022) published 5-year outcomes from SPACE-2.⁴⁵ Median follow-up was 59.9 months (interquartile range, 46.6 to 60). The cumulative incidence of any stroke (ischemic or hemorrhagic) or death from any cause within 30 days, or any ipsilateral ischemic stroke within 5 years of follow up was 2.5% (95% CI, 1.0 to 5.8), 4.4% (95% CI, 2.2 to 8.6), and 3.1% (95% CI, 1.0 to 9.4) with CEA plus BMT, CAS plus BMT, and BMT alone, respectively. No significant difference in risk for the primary efficacy endpoint was found for CEA plus BMT versus BMT alone (HR, 0.93; 95% CI, 0.22 to 3.91; p = .93) or for CAS plus BMT versus BMT alone (HR, 1.55; 95% CI, 0.41 to 5.85; p = .52). Since superiority of CEA or CAS to BMT was not demonstrated, noninferiority testing was not conducted. In both the CEA and CAS groups, 5 strokes and no deaths occurred in the 30-day periprocedural period. During 5-year follow-up, 3 ipsilateral strokes occurred in both the CAS plus BMT and BMT alone groups compared to none in the CEA plus BMT group.

The ongoing Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial (CREST-2; NCT02089217) may elucidate whether CAE or CAS plus contemporary intensive medical management is superior in preventing stroke beyond medical management alone.⁴⁶ The primary outcome consists of the composite of stroke and death within 44 days of randomization and incidence of ipsilateral stroke through 4 years. Change in cognition and differences in major and minor stroke are planned secondary outcomes.

Section Summary: Randomized Controlled Trials of Carotid Artery Stenting Versus Carotid Endarterectomy
Randomized controlled trials comparing CEA with CAS enrolled a mix of symptomatic and asymptomatic patients and employed different selection criteria for participating centers. Periprocedural stroke and death rates following CAS often exceeded those after CEA. Following the early perioperative period (≥ 31 days), the rates of ipsilateral stroke and/or transient ischemic attack appear to be similar for the 2 procedures. While some trials found higher restenosis rates after CAS (SAPPHIRE, SPACE, EVA-3S), restenosis in CREST occurred at a similar frequency following either procedure. The rates of early complications in SPACE, EVA-3S, and ICSS exceeded 6.0%. In CREST, periprocedural death or stroke rates with CAS were less than 6% in symptomatic and 3% in asymptomatic patients. Interventionalists in CREST were the most carefully selected in any trial, and the criteria used to credential in other trials has been a focus of criticisms, along with the inconsistent use of EPDs.⁴⁷

No sufficiently powered RCTs have compared CAS with medical therapy to date, and the CREST-2 trial is ongoing. Therefore, it is not possible to determine whether CAS is superior to medical therapy. Since the pivotal CEA versus medical therapy trials, there has been a marked improvement in medical therapy and declining stroke rates in asymptomatic patients with carotid stenosis. In 1993, the Asymptomatic Carotid Surgery Trial reported that the annual ipsilateral stroke rate was approximately 2.0% with medical therapy.4, A meta-analysis of studies completing enrollment between 2000 and 2010 found a pooled estimate for annual ipsilateral stroke incidence of 1.13%. This decrease in stroke risk has been used to argue that medical therapy in asymptomatic patients is preferable to surgical intervention.^27,48,49

Systematic Reviews
Several TEC Assessments and meta-analyses have been published, all reporting similar findings.^{50,51,52,53,54,55} In average-risk symptomatic patients, the body of evidence has demonstrated worse periprocedural outcomes with CAS than with CEA. For example, a 2020 Cochrane review found CAS associated with an increased risk of periprocedural death or stroke based on 10 RCTs that included 5,396 patients (odds ratio [OR], 1.70; 95% CI, 1.31 to 2.19 ).⁵⁰ Risk of periprocedural death or stroke remained higher with CAS in subgroup analysis of patients younger than age 70 years (OR, 1.11; 95% CI, 0.74 to 1.64 ) and in those patients aged 70 years and older (OR, 2.23; 95% CI, 1.61 to 3.08), although this estimate was not statistically significant. The effect was similar in asymptomatic patients based on 7 trials of 3,378 individuals (OR, 1.72, 95% CI, 1.00 to 2.97). The review also found CAS associated with a significantly increased risk of at least moderate (≥ 50%) restenosis (4 RCTs; n = 2115; OR, 2.00; 95% CI, 1.12 to 3.60) and a nonsignificant risk of severe (≥ 70%) restenosis (9 RCTs; n = 5744; OR, 1.26; 95% CI, 0.79 to 2.00) in a pooled group of symptomatic and asymptomatic patients.

The Carotid Stenosis Trialists’ Collaboration (2016) published an individual patient data meta-analysis (N = 4,754 patients) of SPACE, EVA-3S, and ICSS data, plus data from symptomatic patients in CREST to evaluate the association between age and risk of stroke or death with CEA and CAS.⁵⁶ The periprocedural period was defined as 120 days, which is considerably longer than the conventional 30-day periprocedural definition. For symptomatic patients assigned to CEA, there was no increase in the periprocedural or postprocedural risk of death or stroke for patients older than 65 years compared with those younger than 60 years. In contrast, for patients assigned to CAS, the risk of periprocedural events increased with age, from a 2.1% risk for patients less than 60 years, to 11% for patients over 70 years. These analyses found increased periprocedural stroke risk for CAS versus CEA in patients approximately 65 years and older, but not among those younger patients (an age threshold was not defined). Age was not significantly associated with postprocedural stroke risk. The results would suggest that the risk-benefit profile for CAS in symptomatic patients enrolled in these trials could be modified by age, but there was considerable imprecision in the age-specific CAS versus CEA comparisons for periprocedural risk. For example, among patients ages 60 to 64 years, the HR comparing CAS with CEA for the periprocedural risk of stroke or death was 1.07 (95% CI, 0.56 to 2.01). These results were consistent with those in the 2020 Cochrane review.⁵⁰ In 2019, on behalf of the Carotid Stenosis Trialists’ Collaboration, Brott et al. (2019) published another individual patient data meta-analysis of the same symptomatic patient group (N = 4,775 patients) from SPACE, EVA-3S, ICSS, and CREST to evaluate long-term outcomes (mean follow-up of 4 years).⁵⁷ Periprocedural and postprocedural risks continued to favor CEA.

Paraskevas et al. (2014) conducted a systematic review of studies comparing cognitive outcomes after CEA with those after CAS.⁵⁸ Thirteen studies were included, with heterogeneity in the types of cognitive outcome measures reported. In qualitative analysis, reviewers found that most studies did not report a significant difference between CEA and CAS regarding cognitive outcomes and that heterogeneity across outcomes reported precluded more definitive conclusions.

Wang et al. (2022) conducted a meta-analysis of 7 RCTs, including ASCT-2, reporting outcomes for 7,118 asymptomatic patients.⁵⁹ No significant difference was observed with CAS compared to CEA in the perioperative composite outcome of stroke, death, or any MI (OR, 1.13; 95% CI, 0.87 to 1.47; p = .37). However, CAS had a higher risk of any stroke (OR, 1.62; 95% CI, 1.16 to 2.24; p = .004) and nondisabling stroke (OR, 1.81; 95% CI, 1.23 to 2.65; p = .003). No significant difference in risk of disabling stroke and death was detected between groups (OR, 0.91; 95% CI, 0.50 to 1.65; p = .76).

Section Summary: Systematic Reviews
The systematic reviews comparing CAS with CEA have corroborated the results of individual RCTs that early adverse events are higher with CAS than with CEA, that long-term stroke rates following the perioperative period are similar, and that restenosis rates are higher with CAS. These data would indicate that, for the average-risk patient with carotid stenosis, CAS is associated with net harm compared with CEA. A recent meta-analysis of RCTs with asymptomatic patients demonstrated a higher risk of any stroke or nondisabling stroke in the periprocedural period.

Periprocedural Death or Stroke Rates Following Carotid Artery Stenting
Questions of periprocedural death or stroke rates were assessed in a TEC Assessment (2010).⁶⁰ Given that CAS (like CEA) trades the procedure-related risks of stroke and death for a reduced risk of stroke over subsequent years, and limits for periprocedural stroke and death rates that can be assumed to achieve a net clinical benefit outlined in current guidelines are less than 3% for asymptomatic and less than 6% for symptomatic patients, the Assessment sought evidence to address 2 questions: (1) Is the periprocedural rate of death or stroke with CAS less than 3% for asymptomatic and less than 6% for symptomatic patients?, and (2) For those subgroups defined by (a) medical comorbidities or (b) unfavorable anatomy, are periprocedural rates of death or stroke with CAS less than 3% for asymptomatic and less than 6% for symptomatic patients?

To address the first question, the Assessment identified 18 multicenter prospective registries collectively enrolling 20,194 patients. Eleven of those registries enrolled patients in accordance with the U.S. Food and Drug Administration labeling and with 30-day outcomes available for analysis by symptomatic status (13,783 asymptomatic; 3,353 symptomatic). In 9 of those registries, 30-day death or stroke rates were either reported or obtained from investigators, and in the remaining 2, death or stroke rates were estimated from 30-day death/stroke/MI and MI rates. An independent assessment of neurologic outcomes was required in all but 1 registry. For asymptomatic patients, the pooled periprocedural death or stroke rate was 3.9% (95% CI, 3.3 to 4.4 ; I2 = 57%); for symptomatic patients, it was 7.4% (95% CI, 6.0 to 9.0 ; I2 = 59%).

A subsequent systematic review, without consideration to the Food and Drug Administration labeling, reported results consistent with the TEC Assessment (pooled periprocedural death/stroke rates in asymptomatic patients of 3.3% [95% CI, 2.6 to 4.1 ; 23 studies; n = 8,504 patients] and in symptomatic patients of 7.6% [95% CI, 6.3 to 9.1 ; 42 studies; n = 4910 patients]).⁶¹

To address the second question, the Assessment found that combined data from 2 registries reported periprocedural death or stroke rates for patients with unfavorable anatomy.^62,63 However, this included only 371 asymptomatic (30-day death or stroke rate, 2.7%; 95% CI, 1.5 to 4.9 ) and 60 symptomatic patients (30-day death or stroke rate, 1.7%; 95% CI, 0.3 to 8.9). No other registry reported results by symptomatic status for those subgroups.

Since the 2010 TEC Assessment, additional evidence has been published on rates of periprocedural stroke and death following CAS, particularly for subgroups defined by medical comorbidities. Spangler et al. (2014) evaluated patients treated with isolated primary CEA (n = 11,336) or primary CAS (n = 544) at 29 centers between 2003 and 2013 to assess periprocedural mortality and stroke risks for those considered medically high-risk.⁶⁴ A Cox proportional hazards model was used to generate predicted 5-year mortality, and patients in the highest risk score quartile were considered high-risk. For asymptomatic patients, there were no significant differences between CEA and CAS for major periprocedural outcomes (major or minor stroke, MI, death) for either the high- or low-risk groups. Periprocedural death or stroke rates with CAS were 1.1% for low-risk patients and 1.6% for high-risk patients. For symptomatic patients, periprocedural death or stroke rates were higher with CAS than with CEA for both the low- and high-risk groups. For low-risk symptomatic patients, periprocedural death or stroke rates were 6.0% for CAS and 2.2% for CEA (p < .01). For high-risk symptomatic patients, periprocedural death or stroke rates were 9.3% for CAS and 2.5% for CEA (p < .01).

Observational Study
Salzler et al. (2017) conducted a large retrospective analysis of the increased use of CAS since the Centers for Medicare & Medicaid guidelines recommended CAS for high-risk patients needing carotid revascularization.⁶⁵ Data from the Nationwide Inpatient Sample were searched for patients undergoing carotid revascularization. From 2005 (when the guidelines were published) to 2011, 20,079 CEAs and 3,447 CASs were performed on high-risk patients. During the study period, CAS utilization increased significantly among all high-risk patients. A subgroup analysis of symptomatic high-risk patients did not show an increase in CAS use, indicating that the increase in CAS was primarily in asymptomatic high-risk patients. The odds of in-hospital mortality (OR, 2.6; 95% CI, 1.2 to 5.6) and postoperative in-hospital stroke (OR, 1.5; 95% CI, 1.1 to 3.7) were independently and significantly higher in patients undergoing CAS compared with CEA in the overall sample of high-risk patients.

Transcarotid Artery Revascularization Versus Transfemoral Carotid Artery Stenting
Naazie et al. (2020) published a systematic review and meta-analysis of 9 nonrandomized studies including 4012 individuals who underwent transcarotid artery revascularization (TCAR) and smaller comparative analyses of outcomes between TCAR and transfemoral CAS (TF-CAS; 2 studies) or CEA (4 studies).⁶⁶ Periprocedural (30-day) rates of stroke or death, stroke, death, MI, stroke/death/MI, or cranial nerve injury were 1.89% (95% CI, 1.50 to 2.37), 1.34% (95% CI, 1.02 to 1.75), 0.76% (95% CI, 0.56 to 1.08), 0.60% (95% CI, 0.23 to 1.59), 2.20% (95% CI, 1.31 to 3.69), and 0.31% (95% CI, 0.12 to 0.83), respectively. The perioperative risks of stroke (1.33% vs. 2.55%; OR, 0.52; 95% CI, 0.36 to 0.74) and death (0.76% vs. 1.46%; OR, 0.52; 95% CI, 0.32 to 0.84) were significantly lower with TCAR compared to TF-CAS. When compared against CEA, no statistically significant differences were observed for rates of stroke or death, stroke, or stroke/death/MI with TCAR. However, the risk of death alone was significantly elevated with TCAR (0.81% vs. 0.41%; OR, 1.92; 95% CI, 1.01 to 3.67). Analysis of data based on symptomatic status was not feasible. The authors note that larger, prospective studies comparing TCAR with TF-CAS and CEA are needed, particularly in high-risk patients.

Carotid Artery Stenting for Carotid Dissection
Carotid dissection is uncommon (incidence »2 per 100,000/year) and generally occurs in younger individuals.⁶⁷ With a frequently favorable prognosis, conservative therapy with anticoagulants to restore blood flow is typically employed while surgical intervention is reserved for patients whose symptoms fail to respond to conservative care. Some have described CAS as a potential treatment in those instances.^68,69,70 However, there are no clinical trials comparing alternative strategies and interventions. Current guidelines (detailed below) rate CAS for this indication as a class IIb (level of evidence: C) recommendation.

The purpose of the following information is to provide reference material. Inclusion does not imply endorsement or alignment with the evidence review conclusions.

Clinical Input From Physician Specialty Societies and Academic Medical Centers
While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted.

2009 Input
In response to requests, input was received from 4 physician specialty societies (6 reviewers) and 4 academic medical centers while this policy was under review in 2009. (Also, an unsolicited response from a specialty society was received.) Input strongly supported the use of carotid artery stenting (CAS) in recently symptomatic patients where surgical carotid endarterectomy cannot be performed due to anatomic reasons, although acknowledging the limited evidence about this subgroup. The lack of alternative treatments for recently symptomatic patients and the established increased risk of stroke were factors supporting this opinion.

Practice Guidelines and Position Statements
Guidelines or position statements will be considered for inclusion in Supplemental Information if they were issued by, or jointly by, a U.S. professional society, an international society with U.S. representation, or National Institute for Health and Care Excellence (NICE). Priority will be given to guidelines that are informed by a systematic review, include strength of evidence ratings, and include a description of management of conflict of interest.

American Heart Association and American Stroke Association
The American Heart Association and the American Stroke Association (2021) issued guidance for the prevention of stroke in patients with stroke and transient ischemic attack (TIA).⁷¹ They recommended that, for patients with severe extracranial carotid artery stenosis ipsilateral to a nondisabling stroke or TIA, the choice between carotid endarterectomy (CEA) and CAS in patients who are candidates for intervention should be patient specific. Specific recommendations for CAS or CEA are summarized in Table 4.

Table 4. Guidelines for CAS/CEA in Extracranial Carotid Stenosis

Recommendation	CORa	LOEb
In patients with a TIA or nondisabling ischemic stroke within the past 6 months and ipsilateral severe (70% – 99%) carotid artery stenosis, CEA is recommended to reduce the risk of future stroke, provided that perioperative morbidity and mortality risk is estimated to be < 6%.	1	A
In patients with recent TIA or ischemic stroke and ipsilateral moderate (50% – 69%) carotid stenosis as documented by catheter-based imaging or noninvasive imaging, CEA is recommended to reduce the risk of future stroke, depending on patient-specific factors such as age, sex, and comorbidities, if the perioperative morbidity and mortality risk is estimated to be < 6%.	1	B-R
In patients ≥ 70 years of age with stroke or TIA in whom carotid revascularization is being considered, it is reasonable to select CEA over CAS to reduce the periprocedural stroke rate.	2a	B-R
In patients in whom revascularization is planned within 1 week of the index stroke, it is reasonable to choose CEA over CAS to reduce the periprocedural stroke rate.	2a	B-R
In patients with symptomatic severe stenosis (≥ 70%) in whom anatomic or medical conditions are present that increase the risk for surgery (such as radiation-induced stenosis or restenosis after CEA) it is reasonable to choose CAS to reduce the periprocedural complication rate.	2a	C-LD
In symptomatic patients at average or low risk of complications associated with endovascular intervention, when the ICA stenosis is ≥ 70% by noninvasive imaging or > 50% by catheter-based imaging and the anticipated rate of periprocedural stroke or death is < 6%, CAS may be considered as an alternative to CEA for stroke prevention, particularly in patients with significant cardiovascular comorbidities predisposing to cardiovascular complications with endarterectomy.	2b	A

CAS: carotid artery angioplasty with stenting; CEA: carotid endarterectomy; COR: class of recommendation; ICA: internal carotid artery; LOE: level of evidence; TIA; transient ischemic attack.
^a Class I: benefit >>> risk; Class IIa: benefit >> risk; Class IIb: benefit ≥ risk.
^b Level A (data derived from multiple randomized controlled trials, meta-analyses of high-quality RCTs, or RCT corroborated by high-quality registry study); level B-R (data derived from ≥1 randomized controlled trial of moderate quality or meta-analysis of such trials); level C-LD (randomized or nonrandomized observational or registry studies with limitations of design or execution, meta-analyses of such studies, or physiological or mechanistic studies in human subjects).

Society for Vascular Surgery
The Society for Vascular Surgery published updated guidelines for management of extracranial cerebrovascular disease in 2022.⁷² They recommended CEA over transfemoral CAS (TF-CAS) in low- and standard-risk patients with more than 50% symptomatic artery stenosis (strong evidence of high quality). The guidelines note that while present data are inadequate to make a recommendation on the role of transcarotid arterial revascularization (TCAR) in low surgical risk patients with symptomatic carotid stenosis, TCAR is superior or preferable to TF-CAS or CEA for patients with high anatomic and/or physiologic surgical risk.

American Stroke Association
The American Stroke Association (2011), along with 13 other medical societies, issued guidelines on the management of extracranial carotid and vertebral artery diseases, which are summarized in Table 5.^73,74,75

Table 5. Guidelines for Managing Patients With Extracranial Carotid and Vertebral Artery Disease

Recommendation	CORa	LOEb
CAS is indicated as an alternative to CEA for symptomatic patients at average or low-risk of complications associated with endovascular intervention when the diameter of the lumen of the internal carotid artery is reduced by > 70%, as documented by noninvasive imaging or >50% as documented by catheter angiography and the anticipated rate of periprocedural stroke or mortality is < 6% (360)	I	B
Selection of asymptomatic patients for carotid revascularization should be guided by an assessment of comorbid conditions, life expectancy, and other individual factors and should include a thorough discussion of the risks and benefits of the procedure with an understanding of patient preferences	I	C
It is reasonable to choose CEA over CAS when revascularization is indicated in older patients, particularly when arterial pathoanatomy is unfavorable for endovascular intervention	IIa	B
It is reasonable to choose CAS over CEA when revascularization is indicated in patients with neck anatomy unfavorable for arterial surgery	IIa	B
When revascularization is indicated for patients with TIA or stroke and there are no contraindications to early revascularization, intervention within 2 week of the index event is reasonable rather than delaying surgery	IIa	B
Prophylactic CAS might be considered in highly selected patients with asymptomatic carotid stenosis (minimum 60% by angiography, 70% by validated Doppler ultrasound), but its effectiveness compared with medical therapy alone in this situation is not well established	IIb	B
In symptomatic or asymptomatic patients at high-risk of complications for carotid revascularization by either CEA or CAS because of comorbidities, the effectiveness of revascularization versus medical therapy alone is not well established	IIb	B
Carotid angioplasty and stenting might be considered when ischemic neurologic symptoms have not responded to antithrombotic therapy after acute carotid dissection	IIb	C
Except in extraordinary circumstances, carotid revascularization by either CEA or CAS is not recommended when atherosclerosis narrows the lumen by < 50%	III	A
Carotid revascularization is not recommended for patients with chronic total occlusion of the targeted carotid artery	III	C
Carotid revascularization is not recommended for patients with severe disability caused by cerebral infarction that precludes preservation of useful function	III	C

CAS: carotid artery angioplasty with stenting; CEA: carotid endarterectomy; COR: class of recommendation; LOE: level of evidence; TIA; transient ischemic attack.
^a Class I: benefit >>> risk; class IIa benefit >> risk; class IIb benefit ≥ risk; class III: no benefit.
^b Level A (data derived from multiple randomized controlled trials or meta-analyses; multiple populations evaluated); level B (data derived from a single randomized controlled trial or nonrandomized studies; limited populations evaluated); level C (only consensus opinion of experts, case studies, or standard of care; very limited populations evaluated).

U.S. Preventive Services Task Force Recommendations
The U.S. Preventive Services Task Force recommends against screening for asymptomatic carotid artery stenosis in the general adult population (Grade D; reaffirmed in 2021).⁷⁶

Ongoing and Unpublished Clinical Trials
Some currently unpublished trials that might influence this review are listed in Table 6.

Table 6. Summary of Key Trials

NCT No.	Trial Name	Planned Enrollment	Completion Date
NCT05416853	Radial Versus Femoral Access For Carotid ArteryStenting In Patients With Carotid-Artery Stenosis: a Prospective, Randomized, Multicenter, Noninferiority Trial (RACE-CAS)	2688	Aug 2024
NCT02089217	Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial (CREST-2)	2480	Feb 2026
ISRCTN97744893	European Carotid Surgery Trial 2 (ECST-2): a randomized controlled trial	429	Mar 2025
NCT05623904	Carotid Revascularization Versus Best Medical Treatment for Asymptomatic Carotid Stenosis: a Multicenter, Open, Randomized Controlled Trial in Chinese Population	1056	Dec 2025
NCT05465122	Long-Term Observational Extension of Participants in CREST-2 (C2LOE)	1500	May 2026
NCT02850588	TransCarotid Revascularization Surveillance Project of the Society for Vascular Surgery Vascular Quality Initiative (VQI-TCAR)	60000	Dec 2026

ISRCTN: International Standard Randomized Controlled Trial Number; NCT: national clinical trial.

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29. Altinbas A, Algra A, Brown MM, et al. Effects of carotid endarterectomy or stenting on hemodynamic complications in the International Carotid Stenting Study: a randomized comparison. Int J Stroke. Apr 2014; 9(3): 284-90. PMID 23834300
30. Featherstone RL, Dobson J, Ederle J, et al. Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): a randomised controlled trial with cost-effectiveness analysis. Health Technol Assess. Mar 2016; 20(20): 1-94. PMID 26979174
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32. Silver FL, Mackey A, Clark WM, et al. Safety of stenting and endarterectomy by symptomatic status in the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST). Stroke. Mar 2011; 42(3): 675-80. PMID 21307169
33. Lal BK, Beach KW, Roubin GS, et al. Restenosis after carotid artery stenting and endarterectomy: a secondary analysis of CREST, a randomised controlled trial. Lancet Neurol. Sep 2012; 11(9): 755-63. PMID 22857850
34. Brott TG, Howard G, Roubin GS, et al. Long-Term Results of Stenting versus Endarterectomy for Carotid-Artery Stenosis. N Engl J Med. Mar 17 2016; 374(11): 1021-31. PMID 26890472
35. Roffi M, Sievert H, Gray WA, et al. Carotid artery stenting versus surgery: adequate comparisons?. Lancet Neurol. Apr 2010; 9(4): 339-41; author reply 341-2. PMID 20189459
36. Nallamothu BK, Gurm HS, Ting HH, et al. Operator experience and carotid stenting outcomes in Medicare beneficiaries. JAMA. Sep 28 2011; 306(12): 1338-43. PMID 21954477
37. Gonzales NR, Demaerschalk BM, Voeks JH, et al. Complication rates and center enrollment volume in the carotid revascularization endarterectomy versus stenting trial. Stroke. Nov 2014; 45(11): 3320-4. PMID 25256180
38. Meschia JF, Brott TG, Voeks J, et al. Stroke Symptoms as a Surrogate in Stroke Primary Prevention Trials: The CREST Experience. Neurology. Nov 22 2022; 99(21): e2378-e2384. PMID 36028326
39. Rosenfield K, Matsumura JS, Chaturvedi S, et al. Randomized Trial of Stent versus Surgery for Asymptomatic Carotid Stenosis. N Engl J Med. Mar 17 2016; 374(11): 1011-20. PMID 26886419
40. Spence JD, Naylor AR. Endarterectomy, Stenting, or Neither for Asymptomatic Carotid-Artery Stenosis. N Engl J Med. Mar 17 2016; 374(11): 1087-8. PMID 26890473
41. Halliday A, Bulbulia R, Bonati LH, et al. Second asymptomatic carotid surgery trial (ACST-2): a randomised comparison of carotid artery stenting versus carotid endarterectomy. Lancet. Sep 18 2021; 398(10305): 1065-1073. PMID 34469763
42. Li FM, Zhong JX, Jiang X, et al. Therapeutic effect of carotid artery stenting versus endarterectomy for patients with high-risk carotid stenosis. Int J Clin Exp Med. 2014; 7(9): 2895-900. PMID 25356155
43. Kuliha M, Roubec M, Procházka V, et al. Randomized clinical trial comparing neurological outcomes after carotid endarterectomy or stenting. Br J Surg. Feb 2015; 102(3): 194-201. PMID 25511816
44. Reiff T, Eckstein HH, Mansmann U, et al. Angioplasty in asymptomatic carotid artery stenosis vs. endarterectomy compared to best medical treatment: One-year interim results of SPACE-2. Int J Stroke. Mar 15 2019; 15(6): 1747493019833017. PMID 30873912
45. Reiff T, Eckstein HH, Mansmann U, et al. Carotid endarterectomy or stenting or best medical treatment alone for moderate-to-severe asymptomatic carotid artery stenosis: 5-year results of a multicentre, randomised controlled trial. Lancet Neurol. Oct 2022; 21(10): 877-888. PMID 36115360
46. Howard VJ, Meschia JF, Lal BK, et al. Carotid revascularization and medical management for asymptomatic carotid stenosis: Protocol of the CREST-2 clinical trials. Int J Stroke. Oct 2017; 12(7): 770-778. PMID 28462683
47. Gray WA. Carotid stenting or carotid surgery in average surgical-risk patients: interpreting the conflicting clinical trial data. Prog Cardiovasc Dis. 2011; 54(1): 14-21. PMID 21722782
48. Woo K, Garg J, Hye RJ, et al. Contemporary results of carotid endarterectomy for asymptomatic carotid stenosis. Stroke. May 2010; 41(5): 975-9. PMID 20339122
49. Barnett HJ, Pelz DM, Lownie SP. Reflections by contrarians on the post-CREST evaluation of carotid stenting for stroke prevention. Int J Stroke. Dec 2010; 5(6): 455-6. PMID 21050401
50. Müller MD, Lyrer P, Brown MM, et al. Carotid artery stenting versus endarterectomy for treatment of carotid artery stenosis. Cochrane Database Syst Rev. Feb 25 2020; 2(2): CD000515. PMID 32096559
51. Angioplasty and stenting of the cervical carotid artery with distal embolic protection of the cerebral circulation. Technol Eval Cent Assess Program Exec Summ. Feb 2005; 19(15): 1-4. PMID 15714698
52. Ederle J, Featherstone RL, Brown MM. Randomized controlled trials comparing endarterectomy and endovascular treatment for carotid artery stenosis: a Cochrane systematic review. Stroke. Apr 2009; 40(4): 1373-80. PMID 19228850
53. Bangalore S, Kumar S, Wetterslev J, et al. Carotid artery stenting vs carotid endarterectomy: meta-analysis and diversity-adjusted trial sequential analysis of randomized trials. Arch Neurol. Feb 2011;68(2):172-184. PMID
54. Murad MH, Shahrour A, Shah ND, et al. A systematic review and meta-analysis of randomized trials of carotid endarterectomy vs stenting. J Vasc Surg. Mar 2011; 53(3): 792-7. PMID 21216556
55. Economopoulos KP, Sergentanis TN, Tsivgoulis G, et al. Carotid artery stenting versus carotid endarterectomy: a comprehensive meta-analysis of short-term and long-term outcomes. Stroke. Mar 2011; 42(3): 687-92. PMID 21233476
56. Vincent S, Eberg M, Eisenberg MJ, et al. Meta-Analysis of Randomized Controlled Trials Comparing the Long-Term Outcomes of Carotid Artery Stenting Versus Endarterectomy. Circ Cardiovasc Qual Outcomes. Oct 2015; 8(6 Suppl 3): S99-108. PMID 26515216
57. Brott TG, Calvet D, Howard G, et al. Long-term outcomes of stenting and endarterectomy for symptomatic carotid stenosis: a preplanned pooled analysis of individual patient data. Lancet Neurol. Apr 2019; 18(4): 348-356. PMID 30738706
58. Paraskevas KI, Lazaridis C, Andrews CM, et al. Comparison of cognitive function after carotid artery stenting versus carotid endarterectomy. Eur J Vasc Endovasc Surg. Mar 2014; 47(3): 221-31. PMID 24393665
59. Wang J, Bai X, Wang T, et al. Carotid Stenting Versus Endarterectomy for Asymptomatic Carotid Artery Stenosis: A Systematic Review and Meta-Analysis. Stroke. Oct 2022; 53(10): 3047-3054. PMID 35730457
60. Angioplasty and stenting of the cervical carotid artery with embolic protection of the cerebral circulation. Technol Eval Cent Assess Program Exec Summ. Aug 2010; 24(12): 1-3. PMID 21114063
61. Touzé E, Trinquart L, Chatellier G, et al. Systematic review of the perioperative risks of stroke or death after carotid angioplasty and stenting. Stroke. Dec 2009; 40(12): e683-93. PMID 19892997
62. Gray WA, Chaturvedi S, Verta P. Thirty-day outcomes for carotid artery stenting in 6320 patients from 2 prospective, multicenter, high-surgical-risk registries. Circ Cardiovasc Interv. Jun 2009; 2(3): 159-66. PMID 20031712
63. White CJ, Iyer SS, Hopkins LN, et al. Carotid stenting with distal protection in high surgical risk patients: the BEACH trial 30 day results. Catheter Cardiovasc Interv. Apr 2006; 67(4): 503-12. PMID 16548004
64. Spangler EL, Goodney PP, Schanzer A, et al. Outcomes of carotid endarterectomy versus stenting in comparable medical risk patients. J Vasc Surg. Nov 2014; 60(5): 1227-1231.e1. PMID 24953899
65. Salzler GG, Farber A, Rybin DV, et al. The association of Carotid Revascularization Endarterectomy versus Stent Trial (CREST) and Centers for Medicare and Medicaid Services Carotid Guideline Publication on utilization and outcomes of carotid stenting among "high-risk" patients. J Vasc Surg. Jul 2017; 66(1): 104-111.e1. PMID 28502543
66. Naazie IN, Cui CL, Osaghae I, et al. A Systematic Review and Meta-Analysis of Transcarotid Artery Revascularization with Dynamic Flow Reversal Versus Transfemoral Carotid Artery Stenting and Carotid Endarterectomy. Ann Vasc Surg. Nov 2020; 69: 426-436. PMID 32505684
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68. Schirmer CM, Atalay B, Malek AM. Endovascular recanalization of symptomatic flow-limiting cervical carotid dissection in an isolated hemisphere. Neurosurg Focus. Jun 2011; 30(6): E16. PMID 21631217
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70. Asif KS, Lazzaro MA, Teleb MS, et al. Endovascular reconstruction for progressively worsening carotid artery dissection. J Neurointerv Surg. Jan 2015; 7(1): 32-9. PMID 24391159
71. Kleindorfer DO, Towfighi A, Chaturvedi S, et al. 2021 Guideline for the Prevention of Stroke in Patients With Stroke and Transient Ischemic Attack: A Guideline From the American Heart Association/American Stroke Association. Stroke. Jul 2021; 52(7): e364-e467. PMID 34024117
72. AbuRahma AF, Avgerinos ED, Chang RW, et al. Society for Vascular Surgery clinical practice guidelines for management of extracranial cerebrovascular disease. J Vasc Surg. Jan 2022; 75(1S): 4S-22S. PMID 34153348
73. Brott TG, Halperin JL, Abbara S, et al. 2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS guideline on the management of patients with extracranial carotid and vertebral artery disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, and the American Stroke Association, American Association of Neuroscience Nurses, American Association of Neurological Surgeons, American College of Radiology, American Society of Neuroradiology, Congress of Neurological Surgeons, Society of Atherosclerosis Imaging and Prevention, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of NeuroInterventional Surgery, Society for Vascular Medicine, and Society for Vascular Surgery. J Am Coll Cardiol. Feb 22 2011; 57(8): e16-94. PMID 21288679
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77. Centers for Medicare & Medicaid Services (CMS). Decision Memo for Carotid Artery Stenting (CAG-00085R). 2005; https://www.cms.gov/medicare-coverage-database/details/nca-decision-memo.aspx?NCAId = 157. Accessed April 3, 2023.

Coding Section 

Codes	Number	Description
CPT	37215	Transcatheter placement of intravascular stent(s), cervical carotid artery, open or percutaneous, including angioplasty, when performed, and radiological supervision and interpretation; with distal embolic protection
	37216	Transcatheter placement of intravascular stent(s), cervical carotid artery, open or percutaneous, including angioplasty, when performed, and radiological supervision and interpretation; without distal embolic protection
	37217	Transcatheter placement of intravascular stent(s), intrathoracic common carotid artery or innominate artery by retrograde treatment, open ipsilateral cervical carotid artery exposure, including angioplasty, when performed, and radiological supervision and interpretation
	37218	Transcatheter placement of intravascular stent(s), intrathoracic common carotid artery or innominate artery, open or percutaneous antegrade approach, including angioplasty, when performed, and radiological supervision and interpretation
HCPCS
ICD-10-CM	I65.21-I65.29	Occlusion and stenosis of carotid artery code range
ICD-10-PCS		ICD-10-PCS codes are only used for inpatient services
	037H34Z, 037H3DZ, 037H3ZZ, 037H44Z, 037H4DZ, 037H4ZZ, 037J34Z, 037J3DZ, 037J3ZZ, 037J44Z, 037J4DZ, 037J4ZZ, 037K34Z, 037K3DZ, 037K3ZZ, 037K44Z, 037K4DZ, 037K4ZZ, 037L34Z, 037L3DZ, 037L3ZZ, 037L44Z, 037L4DZ, 037L4ZZ, 037M34Z, 037M3DZ, 037M3ZZ, 037M44Z, 037M4DZ, 037M4ZZ, 037N34Z, 037N3DZ, 037N3ZZ, 037N44Z, 037N4DZ, 037N4ZZ	Surgical, upper arteries, dilation, carotid artery, code by body part (common, internal or external, and right or left), approach (percutaneous or percutaneous endoscopic) and device (drug-eluting intraluminal, intraluminal or none)
	037P34Z, 037P3DZ, 037P3ZZ, 037P44Z, 037P4DZ, 037P4ZZ, 037Q34Z, 037Q3DZ,037Q3ZZ, 037Q44Z, 037Q4DZ, 037Q4ZZ	Surgical, upper arteries, dilation, vertebral artery, code by body part (right or left), approach (percutaneous or percutaneous endoscopic) and device (drug-eluting intraluminal, intraluminal or none)
	03CH3ZZ, 03CH4ZZ, 03CJ3ZZ, 03CJ4ZZ, 03CK3ZZ, 03CK4ZZ, 03CL3ZZ, 03CL4ZZ, 03CM3ZZ, 03CM4ZZ, 03CN3ZZ, 03CN4ZZ	Surgical, upper arteries, extirpation, carotid artery, code by body part (common, internal or external, and right or left), and approach (percutaneous or percutaneous endoscopic)
	03CP3ZZ, 03CP4ZZ,03CQ3ZZ, 03CQ4ZZ	Surgical, upper arteries, extirpation, vertebral artery, code by body part (right or left), and approach (percutaneous or percutaneous endoscopic)
Type of service	Surgery
Place of service	Inpatient

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.

Index 
Angioplasty, Carotid Artery
Carotid Artery, Angioplasty and Stenting
Stents, Carotid Artery 

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, Blue Cross Blue Shield Association technology assessment program (TEC) and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies, and accredited national guidelines.

"Current Procedural Terminology © American Medical Association. All Rights Reserved" 

History From 2013 Forward     

01/16/2024	Annual review, no change to policy intent. Updating regulatory status, rationale, and references. Also updating verbiage to indicate that all of the criteria listed must be met to meet medical necessity for this procedure.
08/02/2023	Updating Coding Section. Adding CPT code 37218. No other changes.
01/12/2023	Annual review, no change to policy intent. Updating regulatory, rationale, and references.
01/05/2022	Annual review, no change to policy intent. Updating rationale, references and description
01/06/2021	Annual review, no change to policy intent. Updating guidelines, coding, regulatory status, rationale and references.
01/21/2020	Annual review, no change to policy intent. Updating rationale.
01/25/2019	Annual review, no change to policy intent. Updating rationale and references.
02/16/2018	Annual review, no change to policy intent. Updating description, regulatory status, rationale and references.
01/03/2017	Annual review, no change to policy intent. Updating background, description, rationale and references.
01/13/2016	Annual review, no change to policy intent. Updated background, description, rationale and references. Added regulatory status.
01/27/2015	Annual review, no change to policy intent. Adding description, guidelines and coding. Updating rationale and references.
01/15/2014	Annual review.Updated description, rationale and reference. No change to policy intent.