Clinical UM Guideline

This document addresses (cervical) carotid, vertebral and intracranial artery stent placement with or without angioplasty. Extracranial carotid artery angioplasty with stenting (CAS) or without stenting has been investigated as a minimally invasive alternative to the current standard of care, that being carotid endarterectomy (CEA). CAS can be performed percutaneously (that is, passage of a balloon catheter into the lesion via a femoral or brachial artery, followed by dilatation of the blocked segment and stent placement) or through a small incision in the neck (that is, transcarotid artery revascularization [TCAR]). TCAR employs a flow reversal system to provide continuous embolic protection throughout the CAS procedure for extracranial carotid artery stenosis. Similarly, angioplasty and stenting has been investigated as an alternative treatment for individuals with symptomatic intracranial artery and extracranial vertebrobasilar artery stenosis, since these conditions portend a poor prognosis even with medical therapy, and surgical intervention is associated with considerable morbidity.

Medically Necessary:

Extracranial Stent Placement with or without Angioplasty:

Extracranial carotid artery stent placement with or without angioplasty is considered medically necessary for individuals who meet EITHER A or B of the following criteria and can be safely treated by this approach and who have no angiographically visible intraluminal thrombus:

1. Symptomatic stenosis equal to or greater than 50%, or asymptomatic stenosis equal to or greater than 80%; and
   One or more of the following conditions which put the individual at a high risk or unsuitable for surgery:
   1. Congestive heart failure (NYHA Class III/IV) or left ventricular ejection fraction less than 30%; or
   2. Open heart surgery needed within the next 6 weeks; or
   3. Recent myocardial infarction (greater than 24 hours and less than 4 weeks); or
   4. Severe chronic obstructive pulmonary disease; or
   5. Unstable angina (CCS class III/IV); or
   6. Inability to move the neck to a suitable position for surgery; or
   7. Tracheostomy.
      or
2. Symptomatic stenosis equal to or greater than 50%, or asymptomatic stenosis equal to or greater than 80%; and
   One or more of the following conditions:
   1. Contralateral laryngeal nerve palsy; or
   2. Existence of lesions distal or proximal to the carotid bulb and bifurcation of the common carotid; or
   3. Pseudoaneurysm; or
   4. Radiation-induced stenosis following previous radiation therapy to the neck or radical neck dissection; or
   5. Restenosis after carotid endarterectomy (CEA); or
   6. Severe tandem lesions that may require endovascular therapy; or
   7. Stenosis secondary to arterial dissection; or
   8. Stenosis secondary to fibromuscular dysplasia; or
   9. Stenosis secondary to Takayasu arteritis; or
   10. Stenosis that is surgically difficult to access (for example, high bifurcation requiring mandibular dislocation); or
   11. Stenosis associated with contralateral carotid artery occlusion; or
   12. Inability to move the neck to a suitable position for surgery; or
   13. Tracheostomy.

Note: If, in exceptional circumstances, extracranial carotid artery angioplasty is performed without stent placement, the above medically necessary criteria must still be met.

Intracranial Stent with or without Angioplasty:

Percutaneous intracranial artery stent placement with or without angioplasty is considered medically necessary as part of the treatment of individuals with an intracranial aneurysm when ALL of the following criteria are met:

1. Surgical treatment is not appropriate or attempted surgery was unsuccessful; and
2. Standard endovascular techniques (coiling) are inadequate to achieve complete isolation of the aneurysm because of anatomic considerations which include, but are not limited to:
   1. wide-neck aneurysm (4 mm or more); or
   2. sack-to-neck ratio less than 2:1.

Not Medically Necessary:

Carotid artery angioplasty and stent placement (CAS) is considered not medically necessary when the above criteria are not met, including but not limited to, the following conditions:

1. Complete occlusion (100% stenosis) of the relevant carotid artery; or
2. Severe symptomatic carotid stenosis in individuals not meeting the criteria above; or
3. Symptomatic stenosis less than 50% of the relevant carotid artery; or
4. Asymptomatic stenosis less than 80% of the relevant carotid artery; or
5. Carotid stenosis with angiographically visible intraluminal thrombus; or
6. A stenosis that cannot be safely reached or crossed by endovascular approach.

Percutaneous stent placement with or without associated percutaneous angioplasty is considered not medically necessary when used in the treatment of stenosis of:

1. Vertebral arteries; or
2. Intracranial arteries.

Percutaneous stent placement with or without associated percutaneous angioplasty is considered not medically necessary when used in the treatment of aneurysm of:

1. Vertebral arteries; or
2. Intracranial arteries, except when the criteria above are met.

Percutaneous angioplasty of the intracranial arteries when performed without associated stent placement is considered not medically necessary.

The following codes for treatments and procedures applicable to this guideline are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

Extracranial
When services may be Medically Necessary when criteria are met:

When services are Not Medically Necessary:
For the procedure codes listed above when criteria are not met or for all other diagnoses not listed; or when the code describes a procedure or situation designated in the Clinical Indications section as not medically necessary.

When services are also Not Medically Necessary:

Intracranial
When services may be Medically Necessary when criteria are met:

When services are Not Medically Necessary:
For the procedure codes listed above when criteria are not met or for all other diagnoses not listed; or when the code describes a procedure or situation designated in the Clinical Indications section as not medically necessary.

When services may also be Medically Necessary when criteria are met:

When services are Not Medically Necessary:
For the procedure and diagnosis codes listed above when criteria are not met.

When services are also Not Medically Necessary:
For the following procedure codes, or when the code describes a procedure designated in the Clinical Indications section as not medically necessary.

Background

Approximately 795,000 individuals in the United States have a stroke every year, with 87% of these strokes categorized as ischemic strokes (CDC). Atherosclerotic carotid artery disease is the cause of 10-15% of all ischemic stokes and transient ischaemic attacks (TIAs) (Bonati, 2021).

CEA is considered the established “gold standard” procedure for individuals with symptomatic and significant carotid artery stenosis. The carotid artery is exposed through an incision, and the atherosclerotic plaque causing the narrowing is removed surgically. CEA is an invasive procedure associated with well-defined, (albeit acceptable) complications including the possibility of nerve injury. A percutaneous endovascular approach to addressing the stenosis is attractive, particularly since this technique has been applied successfully in other areas of the vascular tree including the coronary and lower limb circulation. However, unlike coronary or iliac angioplasty, occlusion of the carotid artery may not be amenable to emergency surgical correction. Serious embolic complications including stroke and death are a concern for any intervention.

Stent implantation, to prevent restenosis, is a supplement to angioplasty, in which a balloon introduced via a catheter is inserted through a blockage and expanded to enlarge the vessel, allowing restoration of blood flow. This procedure involves the permanent placement of a mechanical device within blocked arteries or veins, in order to compress the obstructive material and to support the vessel wall, preventing both constriction and further blockage. Insertion of an embolic protection device may accompany stent placement. This device consists of a small wire mesh or basket that is used to capture any embolic debris that may dislodge from the lesion, in order to prevent the debris from reaching the brain or other intracranial areas. Such devices are purported to further decrease the neurologic event risk from CAS.

CAS can be performed via a transfemoral or TCAR approach. The transfemoral approach was developed first and early studies employed the transfemoral approach in individuals who were treated with CAS. TCAR was introduced as a novel CAS option that circumvents several of the high embolic-risk maneuvers found in transfemoral CAS and employs a flow reversal system that provides continuous embolic protection throughout the procedure. Studies employing this technique have reported lower stroke/death rates comparable to CEA while maintaining the minimally invasive benefits of CAS. TCAR appears to have become the preferred method of performing CAS and may challenge CEA as the preferred carotid artery revascularization method (Liang, 2019).

Proposed Benefits

CAS is purported to decrease stenosis in carotid arteries with varying degrees of blockage. Theoretically, with blood flowing more freely through the artery, symptoms, such as TIA, are diminished or relieved completely, and the risk of stroke and associated neurological impairment is also greatly diminished. Although CEA provides the same advantages, CAS is a less invasive procedure and is promoted as an alternative to CEA particularly where an invasive procedure would lead to an elevated risk of complications. Studies show that the technical success of CAS ranges from about 96% to 100% and residual stenosis after CAS ranges from 2% to 15%. Percutaneous intracranial artery stent placement with or without angioplasty is also used in the treatment of intracranial aneurysms where certain clinical factors contribute to high-risk life threatening events and established surgical and medical management strategies are either contraindicated or ineffective.

Risks

Neurologic complications are generally due to embolic debris that dislodged from the site of the lesion either during or after the procedure and may lead to stroke and/or death. Non-neurologic complications (for example, slow heart rate, transient loss of consciousness) may occur during the procedure. Restenosis following stent implantation has also been reported. The overall postoperative neurologic complication rates for CAS of the extracranial carotids for the treatment of stenosis have ranged from about 0% to10%.

Extracranial Stent Placement with or without Angioplasty

Early studies supported that CAS is an acceptable alternative in individuals who are not candidates for CEA due to comorbidities or anatomical restrictions (CAVATAS, 2001; Ederle, 2010; Hobson, 2004b; Hobson, 2008;Gray, 2006; Mas, 2006; Mas, 2008; Ringleb, 2006; Stolker, 2010; Yadav, 2004). The transfemoral approach is associated with a significantly higher risk of stroke or death compared to CEA or TCAR in symptomatic and older individuals (Liang, 2023). TCAR is associated clinical outcomes similar to CEA in individuals who are considered high risk surgical candidates.

CEA remains the gold standard of interventional care, with CAS use considered appropriate as an alternative in those who are at high risk for CEA. A multicenter, open, randomized, controlled trial (RCT), the International Carotid Stenting Study (ICSS), which enrolled only symptomatic individuals with carotid artery stenosis of 50% or greater. A total of 853 participants were randomized to CAS and 857 to CEA. The investigators acknowledged that the follow-up data was insufficient to examine the primary endpoint, that is, 3-year rates of fatal or disabling stroke; only the 30-day morbidity, as reflected by stroke, death, or myocardial infarction (MI) (a secondary endpoint) was reported. In per-protocol analyses, the 30-day stroke and death rate was 3.4% and 7.4% following CEA and CAS, respectively. While 30-day stroke and death rates were not specifically reported in an intention-to-treat analysis, the corresponding estimated rates were 3.4% and 6.8%. There were few periprocedural MIs—3 in the stenting arm (0.4%) and 5 following CEA (0.6%). These preliminary ICSS results are noted to be consistent with two previously reported large RCTs enrolling similar symptomatic individuals (SPACE, EVA-3S). The authors also noted that within the ICSS results, CAS was not performed with periprocedural (30-day) stroke and death rates sufficiently low (that is, less than 6%) to achieve a net clinical benefit and CAS was inferior to CEA (Ederle, 2010).

Although there are few studies dealing with the effect of CAS on symptomatic carotid stenosis due to fibromuscular dysplasia, there are few treatment options for this population. In addition, the rarity of the condition also makes it unlikely that studies with moderate to large sample sizes will be conducted. Consequently, angioplasty with or without stenting remains an important treatment option for these individuals and has been successfully carried out in the practice community. In certain conditions of fibromuscular dysplasia and in situations where stent placement is technically not feasible, angioplasty alone may be performed.

Silver and associates (2011) published results of the CREST study which reported that, although the participating interventionalists performing CAS were highly selected, periprocedural death/stroke rates following CAS exceeded those for CEA: in symptomatic individuals 5.6% versus 2.4%, respectively (the lowest rate for CAS reported in any trial); in asymptomatic individuals 2.6% versus 1.4%, respectively. The RR for periprocedural death/stroke in the symptomatic group was 1.89 (95% confidence interval [CI]: 1.11 to 3.21) and in the asymptomatic group 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 (Silver, 2011).

Brott and colleagues (2016) published the 10-year results of the CREST trial reporting that among 2502 individuals, there was no significant difference in the rate of the primary composite endpoint between the CAS group (11.8%; 95% CI: 9.1 to 14.8) and the CEA group (9.9%; 95% CI: 7.9 to 12.2) over 10 years of follow-up (hazard ratio [HR] 1.10; 95% CI: 0.83 to 1.44). With respect to the primary long-term endpoint, postprocedural ipsilateral stroke over the 10-year follow-up occurred in 6.9% (95% CI: 4.4 to 9.7) of individuals in the CAS group and in 5.6% (95% CI: 3.7 to 7.6) of those in the CEA group. The rates did not differ significantly between groups (HR: 0.99; 95% CI: 0.64 to 1.52). No significant between-group differences with respect to either endpoint were detected when symptomatic and asymptomatic individuals were analyzed separately.

The ROADSTER 2 study of 632 individuals with significant carotid artery disease was intended to evaluate the safety and efficacy of TCAR performed by a broad group of physicians with variable TCAR experience. The ROADSTER 2 study is a prospective, open label, single arm, multicenter, post-approval registry for individuals undergoing TCAR, which included individuals considered at high-risk for complications from CEA with symptomatic stenosis ≥ 50% or asymptomatic stenosis ≥ 80%. The primary end point was procedural success, which encompassed technical success plus the absence of stroke, MI, or death within the 30-day postoperative period. Secondary end points included technical success and individual/composite rates of stroke, death, and MI. All trial participants underwent independent neurological assessments before the procedure, within 24 hours, and at 30 days after TCAR. An independent clinical events committee adjudicated all major adverse events. Between 2015 and 2019, 692 individuals (intent-to-treat population) were enrolled at 43 sites. Sixty cases had major protocol violations, leaving 632 individuals adhering to the FDA approved protocol (per-protocol population). The majority (81.2%) of operators were TCAR naïve before study initiation. Affected individuals underwent TCAR for neurological symptoms in 26% of cases, and all individuals had high risk factors for CEA (anatomic-related 44%; physiological 32%; both 24%). Technical success occurred in 99.7% of all cases. The primary end point of procedural success rate in the intent-to-treat population was 96.5% (per-protocol 97.9%). The early postoperative outcomes in the intent-to-treat population included stroke in 13 individuals (1.9%), death in 3 cases (0.4%), and MI in 6 individuals (0.9%). The composite 30-day stroke/death rate was 2.3%, and stroke/death/MI rate was 3.2%. In the per-protocol population, there were strokes in 4 individuals (0.6%), death in 1 case (0.2%), and MI in 6 individuals (0.9%) leading to a composite 30-day stroke/death rate of 0.8% and stroke/death/MI rate of 1.7%. The authors concluded that TCAR results in excellent early outcomes with high technical success combined with low rates of post procedure stroke and death. It was noted that these results were achieved by a majority of operators new to this technology at the start of the trial. Adherence to the study protocol and peri-procedural antiplatelet therapy optimized these outcomes (Kashyap, 2020).

In 2020, Naazie and colleagues conducted a systematic review and meta-analysis of TCAR with dynamic flow reversal vs. transfemoral CAS (TFCAS) and CEA. Nine nonrandomized studies evaluating 4012 individuals who underwent TCAR were included. The overall 30-day risks after TCAR were stroke/death 1.89% (95% CI: 1.50, 2.37); stroke 1.34% (95% CI: 1.02, 1.75); death 0.76% (95% CI: 0.56, 1.08); MI 0.60% (95% CI: 0.23, 1.59); stroke/death/MI 2.20% (95% CI: 1.31, 3.69); and cranial nerve injury (CNI) 0.31% (95% CI: 0.12, 0.83). The failure rate of TCAR was 1.27% (95% CI: 0.32, 4.92). Two nonrandomized studies suggested that TCAR was associated with lower risk of stroke and death, as compared with TFCAS (1.33% vs. 2.55%; Odds Ratio [OR]: 0.52, 95% CI: 0.36, 0.74 and 0.76% vs. 1.46%; OR: 0.52, 95% CI: 0.32, 0.84, respectively). Four nonrandomized studies suggested that TCAR was associated with a lower risk of CNI (0.54% and 1.84%; OR: 0.52, 95% CI: 0.36, 0.74) than CEA, but no statistically significant difference in the 30-day risk of stroke, stroke/death, or stroke/death/MI. The authors concluded that among those undergoing TCAR with dynamic flow reversal for carotid stenosis the 30-day risk of stroke or death was low. The perioperative stroke/death rate of TCAR was similar to that of CEA while CNI risk was lower. Additional meta-analyses have generally found that restenosis is more common following CAS than CEA (Bangalore, 2011; Economopoulos, 2011; Murad, 2011).

In 2019, the SVS Vascular Quality Initiative (VQI) reported results of the TCAR Surveillance Project (TSP), which was designed to evaluate the safety and effectiveness of TCAR in real-world practice. Data from the initial 646 individuals enrolled in the TSP from March 2016 to December 2017 were analyzed and compared with those of trial individuals who underwent TFCAS between 2005 and 2017. Individuals who underwent either of the two procedures were matched on age, ethnicity, coronary artery disease, congestive heart failure, prior coronary artery bypass graft or percutaneous coronary intervention, chronic kidney disease, degree of ipsilateral stenosis, American Society of Anesthesiologists class, symptomatic status, restenosis, anatomic and medical risk, and urgency of the procedure. The investigators noted that, compared with individuals undergoing TFCAS (n=10,136), those undergoing TCAR (n=638) were significantly older, had more cardiac comorbidities, were more likely to be asymptomatic, and less likely to have a recurrent stenosis. The results showed that rates of in-hospital TIA/stroke, as well as of TIA/stroke/death were significantly higher in the TFCAS group, compared with the TCAR group (3.3% vs 1.9% [p=0.04] and 3.8% vs 2.2% [p=0.04], respectively). In both procedures, symptomatic individuals had higher rates of TIA/stroke/death, compared with asymptomatic individuals (for TCAR 3.7% vs 1.4% [p=0.06]; for TFCAS 5.3% vs 2.7% [p<0.001]). After multivariable adjustment, there was a trend for increased stroke or death rates in the TFCAS group, compared with the TCAR group but it was not statistically significant (2.5% vs 1.7%; p=0.25; OR: 1.75, 95% CI: 0.85-3.62). However, the TFCAS group was associated with twice the odds of in-hospital adverse neurologic events and TIA/stroke/death, compared with the TCAR group (OR: 2.10; 95% CI: 1.08-4.08; p=0.03), independent of symptom status. Coarsened exact matching showed similar results. These preliminary results of the VQI TSP demonstrated beneficial effects for TCAR compared with TFCAS in real-world practice (Malas, 2019).

In a 2020 comparative study by Schermerhorn and colleagues,  in-hospital outcomes for individuals undergoing TCAR and CEA from January 2016 to March 2018 were reviewed. Data from the SVS VQI TSP registry and the SVS VQI CEA database was used. The primary outcome was a composite of in-hospital stroke and death. A total of 1182 individuals underwent TCAR, compared with 10,797 individuals who underwent CEA. The individuals undergoing TCAR were older (median age, 74 vs 71 years) and more likely to be symptomatic (32% vs 27%); they also had more medical comorbidities, including coronary artery disease (55% vs 28%), chronic heart failure (20% vs 11%), chronic obstructive pulmonary disease (29% vs 23%), and chronic kidney disease (39% vs 34%). On unadjusted analysis, the TCAR group had similar rates of in-hospital stroke/death (1.6% vs 1.4%) and stroke/death/MI (MI; 2.5% vs 1.9%), compared with CEA. There was no difference in rates of stroke (1.4% vs 1.2%), in-hospital death (0.3% vs 0.3%), 30-day death (0.9% vs 0.4%), or MI (1.1% vs 0.6%). However, on average, the TCAR procedures were 33 minutes shorter than CEA procedures (78 ± 33 minutes vs 111 ± 43 minutes). Those undergoing TCAR were also less likely to incur CNI (0.6% vs 1.8%) and less likely to have a postoperative length of stay > 1 day (27% vs 30%). On adjusted analysis, there was no difference in terms of stroke/death (OR:1.3; 95% CI: 0.8-2.2), stroke/death/MI (OR: 1.4; 95% CI: 0.9-2.1), or the individual outcomes. Despite a substantially higher medical risk in those undergoing TCAR, the in-hospital stroke/death rates were similar between the TCAR and CEA groups.

Available data from prospective single-arm studies, and comparative analyses of registry data have demonstrated similar major outcomes from TFCAS and TCAR procedures for carotid stenosis, with lower adverse event rates from TCAR. There is a need for RCTs to be done to obtain level 1 evidence and further validate these preliminary findings (Kashyap, 2022; Lackey, 2020; Liang, 2020). However, for individuals who are unable to undergo CEA due to the presence of high- risk features, the use of CAS is viable alternative therapy.

CAS in Standard Risk Individuals

In 2023, Liang and associates compared the clinical outcomes in individuals who underwent TCAR versus those who underwent CEA. The authors evaluated data obtained from the multicenter Vascular Quality Initiative Carotid Artery Stent and Carotid Endarterectomy registries. Individuals categorized as being a standard surgical risk underwent TCAR (n=2962) or CEA (n=35,063). The primary outcome evaluated was a composite of 30-day stroke, death, or MI, or 1-year ipsilateral stroke. After 1 year, follow-up data was available for 33.2% (983) in the TCAR group and 49.7% (17,438) in the CEA group. After propensity score matching, the study found no statistically significant difference in the risk of the primary composite outcome between TCAR and CEA. The risk of 1-year ipsilateral stroke was higher with TCAR compared to CEA (1.6% versus 1.1%; absolute difference: 0.52%; 95% CI: 0.03–1.08; Relative Risk [RR]: 1.49; 95% CI: 1.05 to 2.11; p=0.03). The clinical value of the results of this study were limited by the lack of follow-up data in both groups. The analysis outcomes from this non-randomized retrospective analysis needs further evaluation in RCTs.

In 2016, Rosenfield and colleagues published the results of a prospective multi-center trial, the Asymptomatic Carotid Trial (ACT)I which compared CAS with embolic protection and CEA in individuals 79 years of age or younger who had severe carotid stenosis of the carotid artery bifurcation, caused by atherosclerotic disease, and were asymptomatic, (that is, no history of stroke, TIA, or amaurosis fugax in the 180 days before enrollment). Notably, participants in the ACT I trial were not considered to be at high risk for surgical complications. Individuals were randomly assigned in a 3:1 ratio to undergo CAS with embolic protection (stenting group) or CEA (endarterectomy group). The trial was designed to enroll 1658 individuals but was halted early, due to slow enrollment, after 1453 individuals underwent randomization. Trial participants were followed for up to 5 years post-procedure. The primary composite endpoint of death, stroke, or MI within 30 days after the procedure or ipsilateral stroke within 1 year was tested at a noninferiority margin of 3 percentage points. Results were reported that reflected that CAS was noninferior to CEA with regard to the primary composite endpoint (event rate, 3.8% and 3.4%, respectively; p=0.01 for noninferiority). The rate of stroke or death within 30 days was 2.9% in the CAS group and 1.7% in the CEA group (p=0.33). From 30 days to 5 years after the procedure, the rate of freedom from ipsilateral stroke was 97.8% in the CAS group and 97.3% in the CEA group (p=0.51), and the overall survival rates were 87.1% and 89.4%, respectively (p=0.21). The cumulative 5-year rate of stroke-free survival was 93.1% in the CAS group and 94.7% in the CEA group (p=0.44). The authors concluded that CAS was noninferior to CEA with regard to the rate of the primary composite endpoint at 1 year. In analyses that included up to 5 years of follow-up, there were no significant differences between study groups in the rates of non-procedure-related stroke, all stroke, and survival. The authors concluded that CAS was noninferior to CEA for the treatment of asymptomatic severe carotid stenosis. There were a number of study factors which may have influenced study outcomes including the last of medical therapy only group treatment arm and the lack of details regarding the affected population which was screened, but not enrolled.

Columbo and colleagues (2023) analyzed data from the vascular quality initiative (VQI) registry to review trends  in the utilization of  TCAR. Individuals included in the analysis included those considered high-risk or standard-risk surgical candidates. (n=31447). Between 2016 and 2022 the use of TCAR increased dramatically. While the use of TCAR is more commonly used in high-risk individuals, use in the standard-risk population has increased as well. The authors note:

It is worth highlighting that the rapid adoption and broad diffusion of TCAR documented herein have occurred in the absence of a dedicated randomized clinical trial. Approved procedures for carotid stenosis have traditionally rested on a strong foundation of level 1 evidence. Both CEA and TF-CAS have been the focus of multiple randomized clinical trials documenting their efficacy and long-term durability. In contrast to this precedent, to date, no randomized trial comparing TCAR to CEA, TF-CAS, or medical therapy has been completed or is enrolling. Furthermore, TCAR’s long-term durability still remains unknown, as currently, 1-year outcome estimates are the longest follow-up available among large observational studies. Despite this, in May, 2022, the FDA granted an expanded indication to TCAR, approving its use among standard-risk patients. This widespread utilization and now expanded FDA approval highlights the need for a rigorous randomized trial to determine the safety and efficacy profile of TCAR versus other treatment modalities, which cannot be established with registry studies alone.

Intracranial Artery Stent Placement with or without Angioplasty for the Treatment of Intracranial Arterial Aneurysms

Once intracranial aneurysms (IAs) are identified, the features are evaluated to determine the most appropriate treatment. The American Heart Association (AHA, 2009) provides recommendations regarding standardized reporting of IAs which include:

1. With multiple aneurysms, each aneurysm must be described separately.
2. Aneurysm location is described on the basis of the vessel of neck origin and, often, the closest branch vessel. For example, ICA IAs should be named on the basis of the nearest branch vessel, including the meningohypophyseal trunk; superior hypophyseal, ophthalmic, anterior choroidal, or posterior communicating artery; or location at the carotid terminus. Use of bony landmarks (eg, supraclinoid) for description is less precise and should be avoided.

IAs are associated with a significant morbidity and mortality risk. Unruptured IAs are a common finding during neuroimaging. When unruptured IAs are identified, it is standard of care to treat these abnormalities when there is a high risk of rupture. Ruptured IAs are treated to prevent rehemorrhage (Chung, 2022).

The International Study of Unruptured Intracranial Aneurysms (ISUIA) trial assessed 4060 individuals with unruptured aneurysms, recording the natural history of those who had no surgery and evaluating morbidity and mortality associated with repair of unruptured aneurysms by surgical clipping or endovascular repair. Over a 5-year period, 18% of the 1692 trial participants who did not receive endovascular or surgical treatment died due to intracranial hemorrhage. Outcomes were much better for the 451 individuals who received endovascular therapy and the 1917 individuals who received surgical clipping with death rates of 1.8% and 1.5%, respectively (Wiebers, 2003).

A clinical series describing use of stents in treating intracranial aneurysms was published in 2010 (Piotin) reporting on a series of 1137 individuals (1325 aneurysms) treated between 2002 and 2009. In this series, 1109 individuals with aneurysms (83.5%) were treated without stents (coiling) and 216 (16.5%) were treated with stents (15 balloon-expandable and 201 self-expandable stents). Stents were delivered after coiling in 55% (119/216) and before coiling in 45% (97/216) of the cases. Permanent neurological procedure-related complications occurred in 7.4% (16 of 216) of the procedures with stents versus 3.8% (42 of 1109) in the procedures without stents. Procedure-induced mortality occurred in 4.6% (10 of 216) of the procedures with stents versus 1.2% (13 of 1109) in the procedures without stents. A total of 53% (114 of 216) of individuals with aneurysms treated with stents and 70% (774 of 1109) of individuals with aneurysms treated without stents were included in the series. Angiographic recurrence was reported in 14.9% (17 of 114) of stent-treated individuals versus 33.5% (259 of 774) of individuals treated with coiling without stenting (p<0.0001; OR: 0.3485; 95% CI: 0.2038-0.5960). Based on this series, the authors concluded that use of stents was associated with a significant decrease of angiographic recurrences, but with more lethal complications compared with coiling without stents. However, the current evidence does not demonstrate the safety or efficacy of percutaneous angioplasty procedures without stent placement for the treatment of intracranial aneurysms (Piotin, 2010). Observational studies with limited participants show that stenting may be safe and effective in those individuals with limited interventional options. Additional data to further define the technical challenges in stent deployment, the durability of endovascular stent grafting for intracranial aneurysms and the exact role of this treatment are recommended (Biondi, 2007; Mocco, 2009; Wajnberg, 2009).

Santillan and associates (2011) published results of the Safety and Efficacy of Neuroform3 for Intracranial Aneurysm Treatment (SENAT) trial that included 79 individuals harboring wide-necked intracranial aneurysms who were treated using the Neuroform3 stent. The stenting procedure failed in 2 individuals. Therefore, 77 individuals harboring 79 intracranial aneurysms were included for analysis. Subject and aneurysm characteristics, progression of aneurysm occlusion, and occurrence of complications were analyzed with follow-up imaging that included digital subtraction angiography (DSA) or MRA. Overall, complete aneurysm occlusion was observed in 42.4% of the cases immediately after treatment and progressed to 96.5% at 7-year follow-up. The mean angiographic follow-up time was 25.8 months (range, 0-84 months). Retreatment was required for 11 aneurysms (14%). A total of 68 individuals (88.3%) had a favorable clinical outcome with a modified Rankin Scale (mRS) ≤ 1; 3 individuals (3.9%) had an mRS of 2 and 5 (6.5%) did not have a clinical follow-up. The mean clinical follow-up time was 45.4 months (range, 3-92 months). One subject (1.3%) died from a procedure-related hemorrhage. The authors concluded that treatment with stent-assisted coil embolization of wide-necked intracranial aneurysms prevented hemorrhage and provides a high rate of aneurysm occlusion at long-term follow-up.

Studies using angioplasty/stenting devices and endovascular coils to repair intracranial aneurysms provide evidence demonstrating improved short-term outcomes when compared to medical therapy alone (Fiorella, 2007; Lylyk, 2005; Molyneux, 2009; Murayama, 2003; Pierot, 2010; Raja, 2008; Timaran, 2009). Stents are used along with endovascular coils to treat individuals with aneurysms with challenging anatomy when conventional surgical options are not effective, for example wide-necked aneurysms. Clinical feedback has been consistent regarding the selective use of stents, as part of endovascular treatment of intracranial aneurysms in these situations. Based on the results from these case series, use of stent devices to supplement coil therapy of an aneurysm is appropriate with wide-neck aneurysms (4 mm or more) or when the sack-to-neck ratio is less than 2:1.

Superior Hypophyseal Artery (SHA) Aneurysm

An aneurysm in the SHA region is a rare occurrence. Otawa (2021) defines the area as part of the ICA area noting:

SHA is defined as the blood vessel originating from the medial wall of the internal carotid artery from the vicinity of the dural ring to the bifurcation of the posterior communicating artery and supplying blood to the inferior surface of the optic nerve and chiasm and pituitary stalk.

There are several anatomic obstacles which make surgical treatment of SHA aneurysms difficult and a good potential candidate for endovascular treatment. Chalouhi and colleagues (2012) reported on the safety and efficacy of endovascular techniques to treat SHA aneurysms in a retrospective review. Individuals with an SHA aneurysm (n=87) underwent various endovascular treatments: coil embolization, stent-assisted coiling, balloon-assisted coil embolization and a flow-diversion technique. Over half of the individuals were treated with stent-assisted coiling as the stenting coiling combination was used in cases with wide neck aneurysms, and many SHA aneurysms are complex with wide necks. Stent-assisted coiling was also done when there was an unfavorable neck-to-dome ratio and in rescue cases of coil prolapse. The rate of recurrence was 3.9% and the rate of recurrence requiring further intervention was 1.3%, none of the recurrences were reported in individuals who underwent stent-assisted coiling. There were no major complications and there was a minor complication rate of 2.2%. There were no cases of early or late hemorrhage observed after the initial endovascular treatment.

In 2023 retrospective study, Kang and colleagues reported on the long-term outcomes of individuals who underwent stent-assisted (n=72) or non-stent-assisted (n=55) coiling therapy to treat SHA aneurysms. The average duration of follow-up was 3.12 years. Over the course of follow-up, stent-assisted coiling was connected to lower recurrence and re-treatment rates. Aneurysm rupture and non-stent-assisted coiling independently increase the risk of aneurysm recurrence. Stent-assisted coiling lowers the recurrence rate to 3% compared to non-stent-assisted coiling. When individuals with recurrent SHA aneurysms were treated with stent-assisted coiling, there were no reported cases of recurrence or rebleeding.

Intracranial Artery Stent Placement with or without Angioplasty for the Treatment of Intracranial Arterial Stenosis

The Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial was intended to compare percutaneous transluminal angioplasty and stenting (PTAS) to intensive medical therapy among individuals with 70-99% stenosis. This large trial was sponsored by the Medical University of South Carolina, in collaboration with the National Institutes of Health (NIH) and the National Institute of Neurological Disorders and Stroke (NINDS). The primary outcome measure was to determine whether intracranial stenting with intensive medical therapy is superior to medical therapy alone for preventing secondary stroke in high-risk individuals with symptomatic stenosis of a major intracranial artery. Recruitment took place at 50 sites in the U.S. with a target enrollment of 764 participants. The study was halted early in 2011, due to a higher rate of adverse events in the angioplasty/stenting group (Chaudhry, 2011).

Subsequent further analysis of the SAMMPRIS data have concurred with the preliminary findings noting that the 30-day rate of stroke or death was 14.7% in the PTAS group (nonfatal stroke 12.5%; fatal stroke 2.2%) and 5.8% in the medical management group (nonfatal stroke 5.3%; non-stroke-related death 0.4%; p=0.002). Beyond 30 days, stroke in the same intracerebral territory occurred in 13 individuals in each group. The probability of the occurrence of a primary endpoint event over time differed significantly between the 2 treatment groups (p=0.009), with 1-year rates of the primary endpoint of 20.0% in the PTAS group and 12.2% in the medical management group. The investigators concluded that, in individuals with intracranial arterial stenosis, aggressive medical management was superior to PTAS, both because the risk of early stroke after PTAS was high and because the risk of stroke with aggressive medical therapy alone was lower than expected (Chaudhry, 2011; Chimowitz, 2011; Derdeyn, 2014; Qureshi, 2012; Siddiq, 2012).

The CASSISS trial (China Angioplasty & Stenting for Symptomatic Intracranial Severe Stenosis) evaluated the clinical benefits of intracranial stenting plus medical  therapy compared to medical therapy alone (Gao, 2022). Individuals with TIA or ischemic stroke due to symptomatic severe intracranial atherosclerotic stenosis, resulted in no significant difference in the risk of stroke or death within 30 days or stroke in the qualifying artery territory beyond 30 days through 1 year. The authors concluded that, “Despite efforts to reduce perioperative complication rates by vetting of surgeons and sites and refining patient selection, the findings nonetheless demonstrated no clinical benefit from the addition of stenting to medical therapy for the treatment of symptomatic severe intracranial atherosclerotic stenosis”.

Intracranial Artery Stent Placement with or without Angioplasty for the Treatment of Intracerebral Vasospasm associated with Subarachnoid Hemorrhage (SAH)

In March 2005, the FDA granted an HDE clearance to the CoAxia NeuroFlo^™ catheter for, “The treatment of cerebral ischemia caused by symptomatic vasospasm following aneurysmal subarachnoid hemorrhage (SAH). The device can be secured by either surgical or endovascular intervention for those who have failed maximal medical management.” The CoAxia NeuroFlo catheter (CoAxia, Inc., Maple Grove, MN) is a multi-lumen device with two balloons mounted near the tip. The balloons can be inflated or deflated independently for controlled partial obstruction of aortic blood flow. It is assumed that the obstruction created by the inflated balloons will reduce blood flow to the lower part of the body while increasing blood volume to the upper part of the body, including the brain, without significant increase in pressure. The increase in cerebral blood volume presumably drives blood flow into the penumbra, restoring circulation and improving chances of recovery. This procedure has not exhibited significant cardiac, cerebral, or renal complications in clinical trials. The CoAxia NeuroFlo catheter is inserted through an introducer sheath through the femoral artery, and balloons are placed on either side of the renal arteries. The infra-renal (IR) balloon is inflated first to 70% occlusion. It is recommended that the supra-renal (SR) balloon be inflated to 70% occlusion about 5 minutes later. Treatment with the CoAxia NeuroFlo catheter is recommended only after individuals have failed or are ineligible for medical therapy (FDA, 2005).

Additional small studies of intracranial endovascular angioplasty continue to reflect some benefit for individuals with vasospasm associated with SAH. However, the outcomes data is limited and shows significant complication rates. Further investigation is warranted (Abruzzo, 2012; Jestaedt, 2008; Jun, 2010; Khatri, 2011; Murai, 2005; Turowski, 2005; Velat, 2011; Zwienenberg-Lee, 2008).

Vertebral Arteries

Xu and associates (2022) assessed the safety and efficacy of percutaneous transluminal angioplasty (PTA) with or without stenting in a Cochrane review which included three RCTs. The review compared endovascular therapy combined with medical therapy to medical therapy alone in individuals treated for cerebral ischemia due to vertebral artery stenosis (n=349). Studies included PTA techniques comprised of angioplasty alone, balloon-mounted stenting, and angioplasty followed by self-expanding stent placement. Study participants included individuals with posterior circulation TIA or non-disabling stroke and vertebral artery stenosis of at least 50% or major intracranial artery stenosis of at least 70%. The primary outcomes assessed were 30-day post-randomization death/stroke and fatal/non-fatal stroke after 30 days post-randomization up to the completion of follow-up. There was no significant difference in these outcomes between participants treated with endovascular treatment plus medical treatment and those treated with medical treatment alone. The secondary outcomes included any stroke (ischemic or hemorrhagic) during the entire follow-up period and death during the entire follow-up period. There was no significant difference in these outcomes between the two treatment groups. There are no significant differences in the short-term or long-term risks of stroke, death, or TIA between individuals with symptomatic vertebral artery stenosis treated with endovascular therapy plus medical treatment, in comparison to those exclusively treated with medical treatment. The study included 60 participants with intracranial stenosis with symptomatic vertebral artery stenosis. In this group, endovascular therapy with medical therapy compared to medical therapy alone, reduced the risk of fatal or non-fatal stroke after 30 days randomization. The authors concluded:

This Cochrane review provides low- to moderate-certainty evidence indicating that there are no significant differences in either short or long-term risks of stroke, death, or TIA between people with symptomatic vertebral artery stenosis treated with endovascular therapy plus medical therapy and those treated with medical therapy alone.

There is limited evidence concerning the net benefit of angioplasty and stenting for vertebral arteries. The published studies consist of studies with evidentiary limitations, including being single-arm, single institution, a limited number of participants or short-term results (Compter. 2015; Coward, 2007; El Koussa, 2022). The current evidence does not support the use of angioplasty and stenting of the vertebral arteries is a clinically appropriate treatment.

Other Information

In 2009, the AHA Council on Cardiovascular Radiology and Intervention, Stroke Council, Council on Cardiovascular Surgery and Anesthesia, Interdisciplinary Council on Peripheral Vascular Disease, and Interdisciplinary Council on Quality of Care and Outcomes Research issued a scientific statement titled Indications for Intracranial Endovascular Neuro-interventional Procedures. The recommendation related to endovascular treatment of symptomatic intracranial stenosis was noted as Class IIb with Level of Evidence C (usefulness/effectiveness is unknown/unclear).

In 2011, the American College of Cardiology Foundation/AHA Task Force on Practice Guidelines, and the American Stroke Association (ASA), 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 issued Guidelines on the Management of Patients with Extracranial Carotid and Vertebral Artery Disease. The following recommendations are listed:

Class I:
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 more than 70% as documented by noninvasive imaging or more than 50% as documented by catheter angiography and the anticipated rate of periprocedural stroke or mortality is less than 6% (Evidence Level: B).

Class IIa:
It is reasonable to choose CEA over CAS when revascularization is indicated in older patients, particularly when arterial patho-anatomy is unfavorable for endovascular intervention (Evidence Level: B).

It is reasonable to choose CAS over CEA when revascularization is indicated in patients with neck anatomy unfavorable for arterial surgery (Evidence Level: B) (Brott, 2011).

Regarding use of CAS in asymptomatic disease, the AHA/ASA issued Guidelines for the Primary Prevention of Stroke in 2011, in which it was noted that advances in optimal medical therapy have resulted in uncertainty about the need for, and benefit of, CEA or CAS in the asymptomatic subgroup with carotid artery stenosis. The findings in this document conclude that more data are needed to compare long-term outcomes following CEA and CAS in asymptomatic individuals with carotid artery stenosis (Goldstein, 2011). Another updated guideline, the Society for Vascular Surgery Guidelines for Management of Extracranial Carotid Disease, concurs with the AHA/ASA guidance regarding asymptomatic disease (Ricotta, 2011).

In 2012, standards of practice recommendations were published on behalf of the Society of Neuro Interventional Surgery, which were based on assessment of available evidence from an updated literature review which extracted published literature from 2000 to 2011 regarding the treatment of symptomatic intracranial atherosclerotic disease (ICAD). Evidence was evaluated and classified according to AHA/ASA standards. Investigators concluded that medical management with combination aspirin and clopidogrel for 3 months and aggressive risk factor modification should be first line therapy for individuals with ICAD. Endovascular angioplasty, with or without stenting, is a possible therapeutic option for selected individuals with symptomatic ICAD and may be considered in individuals with symptomatic 70-99% intracranial stenosis when aggressive maximal medical therapy has failed. However, further studies are necessary to define appropriate selection criteria and the best therapeutic approach for various subsets of affected individuals (Hussain, 2012).

In 2013, the AHA Stroke Council, Council on Cardiovascular Nursing, Council on Peripheral Vascular Disease, and Council on Clinical Cardiology issued Guidelines for the Early Management of Patients with Acute Ischemic Stroke which contain two new recommendations that concur with the other specialty medical society guidance regarding extracranial and intracranial artery angioplasty and stenting as a treatment of acute ischemic stroke as follows:

The usefulness of emergent intracranial angioplasty and/or stenting is not well established. These procedures should be used in the setting of clinical trials (Class IIb; Level of Evidence C);

The usefulness of emergent angioplasty and/or stenting of the extracranial carotid or vertebral arteries in unselected patients is not well established (Class IIb; Level of Evidence C).

Use of these techniques may be considered in certain circumstances, such as in the treatment of acute ischemic stroke resulting from cervical atherosclerosis or dissection (Class IIb; Level of Evidence C). (Jauch, 2013).

In 2021, the European Stroke organization published guidelines based on the available evidence regarding the treatment of carotid stenosis using medical, surgical and endovascular therapies (Bonati). In individuals with asymptomatic carotid stenosis in whom revascularization is considered appropriate, CEA is listed as a weak recommendation treatment based on moderate quality evidence. Stenting may be suggested in those individuals who are less suitable for surgery. This suggestion is not evidence based, but based on the clinical opinion of the committee members. The guideline contains the following recommendations regarding symptomatic individuals:

In patients with severe (70–99%) symptomatic carotid artery stenosis, we recommend carotid endarterectomy.
Quality of evidence: High
Strength of recommendation: Strong for carotid endarterectomy

In patients with moderate (50–69%) symptomatic carotid artery stenosis, we suggest carotid endarterectomy.
Quality of evidence: Low
Strength of recommendation: Weak for carotid endarterectomy

In patients with mild (<50%) symptomatic carotid artery stenosis, we recommend against carotid endarterectomy.
Quality of evidence: Very low
Strength of recommendation: Strong against carotid endarterectomy

In patients with symptomatic carotid artery stenosis requiring revascularisation, we recommend endarterectomy as the treatment of choice.
Quality of evidence: Moderate
Strength of recommendation: Strong for carotid endarterectomy

In patients with symptomatic carotid stenosis <70years old requiring revascularisation, we suggest that stenting may be considered as an alternative to endarterectomy.
Quality of evidence: Low
Strength of recommendation: Weak for carotid stenting

A 2022 update to the SVS guideline for management of extracranial cerebrovascular disease (AbuRahma) contains the following excerpt:

Carotid endarterectomy (CEA) remains favored over transfemoral carotid artery stenting (TF-CAS) for most anatomically suited low/standard risk patients with indications for carotid revascularization. Transcarotid artery revascularization (TCAR) is a newer hybrid CAS procedure that places the stent through a small neck incision. In observational studies, TCAR had a lower risk of perioperative stroke compared with TF-CAS, and lower rates of myocardial infarction or cranial nerve injury compared with CEA. For these reasons, the SVS now considers TCAR preferable to TF-CAS or CEA in high surgical risk patients such as those with high-risk carotid or other anatomy, or unacceptably high medical risk.

Angina pectoris: Chest pain that is typically severe and crushing. The individual experiences a feeling of pressure and suffocation just behind the breastbone (the sternum) caused by an inadequate supply of oxygen to the heart muscle.

Canadian Cardiovascular Society (CCS): This organization further defines anginal classes as follows:

Class I:  Ordinary physical activity does not cause angina;
Class II:  Slight limitation of ordinary activity;
Class III: Marked limitation of ordinary physical activity;
Class IV: Inability to carry on physical activity without discomfort.

Carotid arteries: Arteries originating from the aorta that pass through the neck flowing up to the brain. The carotid arteries and their subsequent branches supply approximately 80% of the brain’s blood supply.

Carotid artery angioplasty with stent placement (CAS): This catheter-based procedure involves utilizing a percutaneous endovascular approach (from within the involved vessel) to access an area of vessel stenosis (obstruction). Balloons within the catheter are then sequentially inflated, in order to clear the stenosed lesion within the vessel with endoscopic removal of any atherosclerotic debris (or plaque) followed by deployment of a stent device which is permanently implanted within the stenosed section of vessel to ensure patency. This minimally invasive alternative to open surgery is proposed for treatment of carotid artery stenosis, as well as for treatment of aneurysms (area of vessel wall weakness) within the intracranial cerebral vascular system.

Carotid endarterectomy (CEA): This is a surgical procedure where the fatty build up in the wall of an artery is directly removed. This procedure is most typically done in the carotid artery when there is a severe or symptomatic narrowing of the vessel lumen.

Contralateral: This term refers to the opposite side of the body.

Endovascular coils (also referred to as coil embolization): This refers to a minimally invasive technique where an intracranial aneurysm (weakness in the wall of a vessel) is accessed endovascularly (from within the vessel with use of catheters) to insert small platinum coils. These coils are threaded through the catheter and deployed into the aneurysm to block blood flow into the aneurysm and prevent rupture of the aneurysm. Coil devices have received FDA clearance; the first was the Guglielmi^® Detachable Coil (Boston Scientific, Corp., Fremont, CA) which was cleared under an Investigational Device Exemption (IDE) in 1995.

Fibromuscular dysplasia: This is a non-atherosclerotic, non-inflammatory disease of the blood vessels that most commonly affects the internal carotid and renal arteries. The condition is rare and the cause is unknown, although cigarette smoking and a history of hypertension may increase the risk. The severity of symptoms varies widely and may result in arterial stenosis, aneurysms, and dissection (separation of the layers of the vessel wall) that result in significant morbidity. Therapy may include drug therapy (to treat hypertension that results from renal artery involvement), surgical revascularization, and angioplasty.

Intracranial arteries: These arteries are located within the skull. The intracranial arteries are comprised of branches of the carotid and vertebral arteries that supply blood to the brain, (that is, the anterior, middle and posterior cerebral, vertebrobasilar or basilar).

Stenosis: A narrowing in a blood vessel such as an artery. This narrowing is usually caused by fatty deposits (atherosclerosis) in the vessel wall.

Vertebral arteries: These arteries are located at the back of the neck and originate from the subclavian arteries. The vertebral arteries and their subsequent branches supply approximately 20% of the brain’s blood supply. Vertebral artery and intracranial artery stenosis have a poor prognosis and generally lead to neurological deterioration or death. Medical management is the treatment option most used. Surgical risks and complications are significant.

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ACCULINK Carotid Stent System
Angioguard^™ Emboli Capture Guidewire
CAS
CEA
CoAxia NeuroFlo
Cordis ENTERPRISE Vascular Reconstruction Device and Delivery System
Cordis PRECISE Nitinol Stent System
ENROUTE Transcarotid Neuroprotection and Stent System
Neuroform3
NEUROLINK System
Pipeline Embolization Device
Protege^® GPS^™
Protege^® RX Carotid Stent System
TCAR, Transcarotid Artery Revascularization
Wingspan Stent System with Gateway PTA Balloon Catheter
Woven Endobridge (WEB)

The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.