Percutaneous 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 involves the passage of a balloon catheter into the lesion via a femoral or brachial artery, followed by dilatation of the blocked segment and stent placement.  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.  This document addresses percutaneous extracranial carotid, vertebral and intracranial artery angioplasty with or without stent placement.

Medically Necessary:

Extracranial Angioplasty with Stent Placement:

Percutaneous extracranial carotid artery angioplasty with stent placement (CAS) performed in conjunction with an FDA approved carotid stent system is considered medically necessary for individuals who meet one or more 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 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
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. Radiation-induced stenosis following previous radiation therapy to the neck or radical neck dissection; or
   4. Restenosis after carotid endarterectomy (CEA); or
   5. Severe tandem lesions that may require endovascular therapy; or
   6. Stenosis secondary to arterial dissection; or
   7. Stenosis secondary to fibromuscular dysplasia; or
   8. Stenosis secondary to Takayasu arteritis; or
   9. Stenosis that is surgically difficult to access (e.g., high bifurcation requiring mandibular dislocation); or
   10. Stenosis associated with contralateral carotid artery occlusion; or
   11. Pseudoaneurysm.
       OR
3. Inability to move the neck to a suitable position for surgery.
   OR
4. 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 in individuals with one or both of the following conditions:

1. Carotid stenosis with angiographically visible intraluminal thrombus; OR
2. A stenosis that cannot be safely reached or crossed by endovascular approach. 

Investigational and Not Medically Necessary: 

Carotid artery angioplasty and stent placement (CAS) is considered investigational and 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;
2. Severe symptomatic carotid stenosis in individuals not meeting the criteria above;
3. Symptomatic stenosis less than 50% of the relevant carotid artery;
4. Asymptomatic stenosis less than 80% of the relevant carotid artery.

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

Currently, carotid endarterectomy (CEA) is considered the established "gold standard" procedure for individuals with symptomatic and significant carotid artery stenosis.  However, this is an invasive procedure associated with well-defined, (albeit acceptable) complications including the possibility of nerve injuries. A percutaneous endovascular approach to carotid artery lesions has been 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 remain an issue.

The majority of published data represent prospective uncontrolled studies with a number of variables including candidate selection criteria, type of stent used, and use or non-use of an embolic protection device. Initial studies reported higher complication rates for stroke and/or death than with CEA (10% - 12% for CAS versus 5.8% for CEA). More recent studies, however, including two randomized studies, suggest similar major complication rates for the two procedures, together with similar restenosis rates. However, the two randomized studies were performed at a single institution by a particularly experienced operator and consisted of relatively small sample sizes. Also, in other studies, issues related to candidate selection, inconsistent use of stents and protection devices and short follow-up indicate the need for further larger scale, longer term randomized, controlled studies comparing CAS with CEA to determine the relative efficacy and complication rates of these procedures. The multi-center Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS) randomized 504 mostly symptomatic subjects with 70% carotid artery stenosis to receive endovascular treatment or CEA. There was no difference in the rates of death or stroke at 30 days, and three year follow-up showed no difference in the rate of stroke. This trial has been criticized, however, because the rate of stroke or death was higher than that reported in other randomized trials of CEA. Also, residual restenosis was more frequent with the endovascular approach than CEA (14% versus 4% respectively). However, it should be noted that only 22% of participants in this trial received stents. Two earlier randomized trials of carotid stenting were stopped early because of inferior outcomes, which were thought to be related to earlier stent designs and inexperience with the technique.

Brown MM, the principal investigator of CAVATAS and CAVATAS-2 (an ongoing international study), in an editorial in the American Journal of Medicine (2004) wrote, "There is, therefore, a need for further randomized trials of CAS with protection devices compared with CEA to establish convincingly the value of CAS." Brown further stated: "Although the early results of CAS with protection devices appear encouraging, there are no long term data to rival that available from the carotid surgical trials. Hence, caution argues that stenting should continue to be seen as an experimental procedure and carried out only in the context of randomized clinical trials."

Currently, there are multi-center, randomized, controlled studies in progress in Europe and the United States.  Results of two other trials, the SPACE trial (Stent Supported Percutaneous Angioplasty of the Carotid Artery versus Endarterectomy) and the EVA-3S trial (Endarterectomy versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis) are now available.  The SPACE trial was a randomized non-inferiority trial that provided outcomes data at 30 days which failed to prove the non-inferiority of CAS, compared to conventional CEA.  However, the authors state that the results do not justify widespread use in the short term of CAS, and outcomes at 6-24 months are awaited (Ringleb, 2006). Published results of the EVA-3S trial reported finding that, for symptomatic subjects with carotid stenosis of 60% or more, the rates of death and stroke at 30 days and 6 months following surgery were lower for CEA, compared with CAS (Mas, 2006). 

Four year follow-up results of the EVA-3S trial were recently compiled which found that the safety of stenting needs to be improved for individuals with symptomatic carotid stenosis. This multicenter, randomized trial compared the safety of CAS with CEA. Participants were eligible for the EVA-3S study if they were 18 years or older, had a transient ischemic attack (TIA) or a nondisabling stroke (or retinal infarct) within 120 days before enrollment, and had an atherosclerotic stenosis of 60% to 99% of the symptomatic carotid artery. The study enrolled 527 subjects who were randomly assigned to undergo CEA (n = 262) or CAS (n = 265). The primary endpoint was the rate of any periprocedural stroke or death within 30 days postprocedure; the EVA-3S trial was terminated early because of a higher 30-day risk of stroke or death in the CAS group. The main secondary endpoint was a composite of any periprocedural stroke or death and any nonprocedural ipsilateral stroke during four years of follow-up.

Results of the four years of follow-up of the EVA-3S data found the cumulative probability of periprocedural stroke or death and nonprocedural ipsilateral stroke was higher with CAS than with CEA (11.1% versus 6.2%; hazard ratio [HR], 1.97; 95% confidence interval [CI], 1.06 to 3.67; P = 0.03). The HR for any periprocedural disabling stroke or death or any nonprocedural fatal or disabling ipsilateral stroke was 2.00 (CI, 0.75 to 5.33; P = 0.17).  A hazard function analysis showed the 4-year differences in the cumulative probabilities of outcomes between stenting and CEA were largely accounted for by the higher periprocedural (within 30 days of the procedure) risk of stenting compared with CEA.  After the periprocedural period, the risk of ipsilateral stroke was low and similar in both treatment groups. The authors concluded that for individuals with symptomatic carotid stenosis, CAS is not as safe an alternative as CEA, although CAS is as effective as CEA for prevention of middle-term ipsilateral stroke (Mas, 2008).

Yadav and colleagues reported on results of the SAPPHIRE trial (Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy) in October 2004.  334 participants classified as "high risk," based on the presence of neurological symptoms and a greater than 50% stenosis of the common or internal carotid artery or who were asymptomatic with greater than 80% stenosis, were randomized to CEA or CAS.  Of the 167 subjects randomly assigned to stenting, 159 received the assigned treatment.  Of the 167 assigned to surgery, 151 received the assigned treatment.  All participants also had one or more medical or surgical comorbid conditions that placed them at high risk for CEA.  Exclusion criteria for the trial included history of a bleeding disorder, along with other criteria.  The technique employed Cordis Corporation's PRECISE^™  Nitinol Stent System with the ANGIOGUARD^™  Embolic Capture Guide-wire System.  At one year, superior results were reported for the CAS group as measured by a composite end point of major adverse events including all-cause death, stroke, and myocardial infarction (12% for CAS vs. 20% for CEA).  The authors concluded that among individuals with severe carotid-artery stenosis and coexisting conditions, CAS with the use of an embolic-protection device is not inferior to CEA. Additional information on results of the SAPPHIRE trial were reported recently which indicated that, among subjects at high surgical risk, CAS was associated with less health status impairment during the initial 2 week post-surgical recovery than CEA treated subjects.  However, these differences in quality of life measures resolved by one month post-procedures, and no other differences between the two treatment groups in health-related quality of life were noted (Stolker, 2010).  

Most authors currently writing in the literature are of the opinion that CEA, a proven effective long term surgical approach, remains the gold standard of interventional care and do not advocate the widespread practice of CAS with stenting as an alternative at this time, particularly in those who are not at high risk for CEA.  This includes recently published short-term results of a multicenter, open, randomized, controlled trial, the International Carotid Stenting Study (ICSS) which enrolled only symptomatic subjects within one year and carotid artery stenosis of 50% or greater; 853 participants were randomized to CAS and 857 to CEA.  Randomization procedures effectively concealed allocation to investigators; study subjects were unblinded, and embolic protection devices were recommended, but not required.  The investigators acknowledge that the follow-up data is currently insufficient to examine the primary endpoint, (i.e., 3-year rates of fatal or disabling stroke); 30-day morbidity, as reflected by stroke, death, or myocardial infarction (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, from figures provided, the corresponding estimated rates were 3.4% and 6.8%.  There were few periprocedural myocardial infarctions (MIs)—3 in the stenting arm (0.4%) and 5 following endarterectomy (0.6%).  These preliminary ICSS results are noted to be consistent with two previously reported large randomized controlled trials enrolling similar symptomatic subjects (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 (i.e., less than 6%) to achieve a net clinical benefit and CAS was inferior to CEA (Ederle, 2010).   

Preliminary results were also published recently for the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) which is a large randomized, controlled trial with blinded end-point adjudication.  This ongoing trial is sponsored by the National Institute of Neurological Disorders and Stroke (NINDS) and the National Institutes of Health (NIH).  The primary aim is to compare the outcomes of CAS with those of CEA among subjects with symptomatic or asymptomatic extracranial carotid stenosis.  Trial participants were considered to be symptomatic if they had had a transient ischemic attack, amaurosis fugax, or minor nondisabling stroke involving the study carotid artery within 180 days before randomization.  Eligibility criteria were stenosis of 50% or more on angiography, 70% or more on ultrasonography, or 70% or more on computed tomographic angiography or magnetic resonance angiography if the stenosis on ultrasonography was 50 to 69%.  Eligibility was extended in 2005 to include asymptomatic subjects, for whom the criteria were stenosis of 60% or more on angiography, 70% or more on ultrasonography, or 80% or more on computed tomographic angiography or magnetic resonance angiography if the stenosis on ultrasonography was 50 to 69%.  Subjects were excluded if they had had a previous stroke that was sufficiently severe to confound the assessment of end points.  Trial participants from 108 centers in the U.S. and Canada included 2,502 subjects over a median follow-up period of 2.5 years.  Total numbers were 1,262 received CAS, and 1,240 underwent CEA.  Participants were not randomly assigned to a treatment group until the operators performing both the CAS and CEA procedures had been certified, which included 224 interventionalists who were certified after satisfactory evaluation of their endovascular experience, carotid-stenting results, and participation in both hands-on training and a lead-in phase of training. 

Preliminary results among subjects with symptomatic or asymptomatic carotid stenosis indicated that the risk of the composite primary outcome of stroke, myocardial infarction, or death did not differ significantly in the two treatment groups.  However, it was noted that there was a higher risk of stroke in the CAS group and a higher risk of myocardial infarction in the CEA group during the perioprocedural period.  These countervailing effects during the periprocedural period resulted in similar rates of the primary outcomes, because the rates of events after the periprocedural period were similar in the two groups.  The authors acknowledge that the differential results for myocardial infarction and stroke offer opportunities for improvement in the training of surgeons and interventionalists performing CAS procedures, expanded knowledge and experience with stent designs and embolic protection devices, as well as better informed candidate selection, especially amongst those over 70 years of age.  The authors note that candidate selection may require attention to age for either procedure, due to the association between older age and increased risk for adverse events.  This interaction between age and treatment efficacy was detected at approximately 70 years of age.  The effects of advanced age on the differences between CAS and CEA treated groups were seen in the SPACE trial results, as well as in these early CREST results where younger participants had slightly better outcomes with CAS and older persons had a better outcome with CEA.  The trial investigators speculated that mechanisms underlying the increased risk with CAS in the very elderly (age over 70) probably include vascular tortuosity and severe vascular calcification.  It is generally considered that these preliminary results (mean follow-up of 2.5 years) lack sufficient detail for firm conclusions and are viewed as consistent with the growing body of evidence examining outcomes of CAS in comparison to CEA that indicate that further robust study is needed.  The absence of comparison with current best medical therapy is another significant limitation of CREST (Brott, 2010). 

In August 2004, the US Food and Drug Administration (FDA) granted Premarket Approval (PMA) to Guidant Corporation's two stent systems (the ACCULINK^™  Carotid Stent System and the RX ACCULINK^™ Carotid Stent System), which are used in conjunction with two carotid embolic protection systems (the ACCUNET^™ and the RX ACCUNET^™ Embolic Protection Systems, Guidant Corp.) for the treatment of individuals considered to be at high risk for adverse events from CEA who require carotid revascularization and meet the following criteria:

1. Persons with neurological symptoms and equal to or greater than 50% stenosis of the common or internal carotid artery by ultrasound or angiogram OR persons without neurological symptoms and equal to or greater than 80% stenosis of the common or internal carotid artery by ultrasound or angiogram; AND
2. Individuals must have a reference vessel diameter within the range of 4.0mm and 9.0mm at the target lesion.

As part of this approval, Guidant agreed to conduct long term follow-up of subjects in the studies it submitted to the FDA and conduct another post approval study including 1,000 newly enrolled participants. The data submitted to the FDA, on which its approval was based, were from three prospective, non-randomized, multicenter, single arm trials known as ARCHeR 1, 2 and 3 (ACCULINK for Revascularization of Carotids in High Risk Patients) enrolling a total of 581 subjects who were considered either high risk for CEA or not surgical candidates for current surgical options (CEA) and who were symptomatic with a 50% or greater carotid artery stenosis, or asymptomatic with an 80% or greater stenosis. The ARCHeR results were published in 2006 (Gray, 2006). The primary composite endpoint of 30 day combined incidence of death, stroke and myocardial infarction plus one year incidence of ipsilateral stroke was 9.6%. This was compared to 14.4% for historical surgical controls involving similar high surgical risk populations. Target lesion revascularization at one and two years was 2.2% and 2.9% respectively.  These studies suggested that CAS may be safe and effective in a subset of individuals who are not candidates for CEA.  In 2006, Guidant Corporation's vascular intervention and endovascular business was acquired by Abbott Vascular Solutions, Inc. (Temecula, CA). 

On Sept. 6, 2005, the FDA granted PMA approval to the Xact^™ Carotid Stent System (Abbott Vascular Solutions, Inc.) for use in conjunction with the Abbott Emboshield^® Embolic Protection System for very similar indications to the ACCULINK^™  and RX ACCULINK^™  devices.

Several additional carotid stent and embolic protection systems have been granted PMA approvals by the FDA as substantially equivalent to the RX Acculink^™ and Xact^™ device systems including, but not limited to:  the Protégé^® GPS^™ and Protégé^® RX Carotid Stent Systems used with the SpiderRX^™ Embolic Protection Device (ev3 Inc., Plymouth, MN), which received FDA approval in January 2007. This CAS system was evaluated via the Carotid Revascularization with ev3 Inc. Arterial Technology Evolution (CREATE) Trial. The NexStent^® Carotid Stent and Monorail^® Delivery System (Endotex Interventional Systems, Inc., Cupertino, CA) received FDA approval in October 2006. It is also compatible with the FilterWire EZ^™ Embolic Protection System. FDA approval for the FilterWire EZ Embolic Protection System, as well as for the two associated CAS systems, was based on a prospective, nonrandomized multicenter clinical trial (Carotid Artery Revascularization using the Boston Scientific EPI FilterWire EX and the EndoTex NExStent [CABERNET]). These devices received FDA approval for similar indications to the prior approved devices.

CAS appears to be a reasonable option for select individuals who are poor surgical candidates for reasons of either anatomy or comorbidities, and who otherwise meet the criteria for revascularization. However, CEA remains the gold standard procedure for those who are not at high risk for this procedure.  A report from the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology (Chaturvedi, 2005) commented that there are several important areas for further investigation pertaining to CAS, including the role of cerebral hemodynamics in risk stratification for individuals with carotid stenosis, such as the examination of indices of vaso-reactivity and cerebral perfusion, which has not been emphasized in recent multicenter trials, to date.

Although there are few studies dealing with the effect of carotid artery angioplasty with or without stenting 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 in the near future. Consequently, carotid artery angioplasty with or without stenting remains an important treatment option for these individuals and has been successfully carried out in the community.

There is limited evidence concerning the net benefit of angioplasty and stenting for vertebral arteries and intracranial arteries. The SSYLVIA trial (Stenting of Symptomatic Atherosclerotic Lesions in the Vertebral or Intracranial Arteries) was a multicenter, non-randomized prospective feasibility study using the NEUROLINK^® intracranial stent system. It included 61 symptomatic subjects who had suffered a transient ischemic attack (TIA) or stroke attributable to a single arterial stenosis of at least 50%. Following stent placement, the stroke rate within 30 days was 6.6%, and 30-day to 12 month stroke rate was 7.3%. At six months, the restenosis rate (greater than 50% stenosis) was 32.4% for intracranial stents and 42.9% for extracranial vertebral stents. The investigators acknowledged, "Currently there is no proven benefit of this procedure relative to medical therapy." (SSYLVIA, 2004)

The International Study of Unruptured Intracranial Aneurysms (ISUIA) trial assessed 4,060 subjects 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 five-year period, 18% of the 1,692 trial participants who did not receive endovascular or surgical treatment died due to intracranial hemorrhage.  Outcomes were much better for the 451 subjects who received endovascular therapy and the 1,917 who received surgical clipping with death rates of 1.8% and 1.5%, respectively (Wiebers, 2003).

The largest clinical series describing use of stents in treating intracranial aneurysms was published in 2010 reporting on a series of 1,137 subjects (1,325 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 (logistic regression p = 0.644; odds ratio: 1.289; 95% CI: 0.439–3.779).  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 (logistic regression p = 0.006; odds ratio: 0.116; 95% CI: 0.025–0.531).  Thus far, the authors have followed 53% (114 of 216) of individuals with aneurysms treated with stents and 70% (774 of 1,109) of individuals with aneurysms treated without stents, with angiographic recurrence in 14.9% (17 of 114) versus 33.5% (259 of 774), respectively (p < 0.0001; odds ratio: 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 (Piotin, 2010).  Additional small studies note the need for 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 (Biondi, 2007; Mocco, 2009; Wajnberg, 2009).

An ongoing prospective, multi-center trial is using an observational registry with consecutive intent-to-treat to obtain safety and efficacy data on another stent system, the Neuroform3^™ (Boston Scientific Corp., Natick, MA), which is used in conjunction with occlusive devices, such as coils, for the treatment of wide neck aneurysms.  The Safety and Efficacy of Neuroform3 for Intracranial Aneurysm Treatment (SENAT) trial currently has an estimated completion date of December, 2011.  The objectives of this industry sponsored study are:

• To describe and quantify morbidity-mortality at 1 month and 12-18 months following the treatment of the intracranial aneurysm with the Neuroform3 stent;
• To describe and quantify the adverse events rate;
• To get an angiographic assessment performed at 12-18 months compared to the initial post-treatment assessment consisting of residual aneurysm, modified Rankin scale, and a same/better/worse scale; and
• To get a neurologic assessment: Modified Rankin Scale at 12-18 months, evaluated as a categorical change compared to baseline (NCT00928265).

Another ongoing trial was the Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS), which was intended to compare angioplasty and stenting to intensive medical therapy among subjects 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 the Wingspan stent) with intensive medical therapy is superior to medical therapy alone for preventing secondary stroke in high-risk subjects with symptomatic stenosis of a major intracranial artery. Recruitment was currently underway at 50 sites in the U.S. with a target enrollment of 764 participants.  However, according to a news brief on April 12, 2011, this study has been halted early due to a higher rate of adverse events in the angioplasty/stenting group (NCT00576693).

Another large study, the VISSIT Intracranial Stent Study for Ischemic Therapy, is a multi-center, randomized clinical trial intended to prospectively evaluate the safety, benefit, and effectiveness of the PHAROS Vitesse Neurovascular Stent System, along with best medical therapy, in comparison to best medical therapy alone for the treatment of high-risk subjects with ischemic disease.  This industry sponsored study is slated for completion in June, 2011 (NCT00816166).

In 2009, the American Heart Association 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 on 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).  The level of evidence was the same for use of angioplasty and stenting in the treatment of acute ischemic stroke (Myers, 2009).

Through Humanitarian Device Exemptions (HDEs), the FDA has cleared the following intracranial stent systems: the NEUROLINK^® System (Guidant Corp., Menlo Park, CA) in August 2002 and the Wingspan Stent System^™ with Gateway^™ PTA Balloon Catheter (Boston Scientific Corporation, San Leandro, CA) in August 2005.  The former is indicated for the treatment of individuals with recurrent intracranial stroke caused by atherosclerotic disease refractory to pharmacotherapies, in intracranial vessels ranging from 2.5 to 4.5 mm in diameter with greater than or equal to 50% stenosis that are accessible to the stent system.  The latter (Wingspan) is indicated for improving cerebral artery lumen diameter in individuals with intracranial atherosclerotic disease, refractory to pharmacotherapies, in intracranial vessels with greater than or equal to 50% stenosis that are accessible to the system.  In 2007, the ENTERPRISE^™ Vascular Reconstruction Device and Delivery System (Cordis Neurovascular, Inc., Miami Lakes, FL) also received HDE designation clearance from the FDA for "Use with embolic coils for the treatment of wide-neck, intracranial, saccular or fusiform aneurysms arising from a parent vessel with a diameter of > 3 mm and < 4 mm.  Wide-neck is defined as having a neck width > 4mm or a dome-to-neck ratio < 2."  Although cleared by the FDA, the clinical effectiveness of these intracranial stent systems has not been clearly established.  Preliminary findings, on which the FDA clearances were based, need further validation in large randomized controlled trials.  On April 6, 2011 the FDA announced its clearance of another device for repair of wide neck aneurysms, the Pipeline Embolization Device^™ (ev3, Inc. Menlo Park, CA) which is for use in the endovascular treatment of large wide-necked intracranial aneurysms in the cavernous and paraclinoid regions of the internal carotid artery (FDA, 2011).

In March 2005, the FDA also granted an HDE 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 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 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.  Inflation of both balloons should be maintained for 40 minutes.  Balloon inflation may be modified over this period, based on blood pressure.  The balloons should then be sequentially deflated, SR then IR, and removed. Treatment with the NeuroFlo catheter is recommended only after subjects have failed or are ineligible for medical therapy (FDA, 2005).

Symptomatic intracranial artery stenosis, even when managed medically, carries a poor prognosis (at least a 9-12% annual risk of major stroke or death according to Higashida, 2006).  However, most authors in recent reviews of intracranial artery angioplasty and stenting are of the opinion that further randomized clinical trials are needed, comparing this procedure to best medical management, in order to establish whether long term clinical outcomes are, in fact, improved as a result of angioplasty and stenting (Hartmann, 2005; Higashida, 2006; Komotar, 2005; Hanel, 2005). 

Additional recent research reports on studies using angioplasty/stenting devices and endovascular coils to repair intracranial aneurysms.  There is some 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), however, this evidence is mostly in the form of case reports.  There is much interest in the use of stents, in addition to endovascular coils, when presented with aneurysms with challenging anatomy where 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 rare 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.  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).

Description of Disease

Approximately 700,000 people in the US will have a stroke this year, and close to 30% will be under the age of 65. Stroke is the third leading cause of death in the US and stenosis of one or both of the carotid arteries is a leading risk factor for stroke. Treatment of carotid artery stenosis includes risk factor modification, i.e., smoking cessation, weight reduction, lower cholesterol levels, exercise, reduction of elevated blood pressure, glycemic control, medication (e.g., antiplatelet therapy), and in some cases surgical intervention (CEA, CAS). The NASCET (North American Symptomatic Carotid Endarterectomy Trial), a major trial that confirmed the efficacy of CEA, defined "severe" stenosis to be 70% - 99%. At this level of stenosis, affected individuals are typically referred for CEA if there are no safety issues (e.g., due to comorbidities or characteristics of the lesions).

Fibromuscular dysplasia is a nonatherosclerotic, noninflammatory 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.

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.

Description of Technology

Traditionally, surgical treatment has been with open CEA. The carotid artery is exposed through an incision, and the atherosclerotic plaque causing the narrowing is removed surgically. Recently, CAS emerged as an alternative to open surgery. While carotid angioplasty has been performed alone, currently this procedure typically includes the placement of a stent, in order to prevent restenosis. However, in certain conditions of fibromuscular dysplasia and in situations where stent placement is technically not feasible, angioplasty alone may be performed.

Stent implantation 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.

In 2007, a consensus document on carotid stenting was released by the American College of Cardiology Foundation/Society for Cardiovascular Angiography and Interventions/Society for Vascular Medicine and Biology/Society of Interventional Radiology/American Society of Interventional & Therapeutic Neuroradiology (ACCF/SCAI/SVMB/SIR/ASITN). This document states that, "CAS is viewed as a reasonable alternative to CEA, particularly in subjects at high risk for CEA, and use of EPDs (embolic protection devices) seems to be important in reducing risk of stroke…At the present time, the evidence is insufficient to support CAS in asymptomatic high-risk subjects who have less than 80% stenosis or in those who are not at high-risk for surgery." (Bates, 2007)

In 2003, a collaborative panel of the Joint Standards of Practice Committee of the American Society of Interventional and Therapeutic Neuroradiology, the American Society of Neuroradiology, and the Society of Interventional Radiology developed quality improvement guidelines for the performance of cervical CAS. The document includes standards for qualifications and responsibilities of personnel, specifications of the procedure, equipment quality and control, documentation, thresholds, success and complication rates, quality control and improvement, safety, infection control, and candidate education concerns. Furthermore, the document outlines suggested inclusion criteria and relative and absolute contraindications for CAS (Barr, 2003).

Human Device Exemptions (HDEs) differ from the standard FDA approval process and are designed to allow the use of qualified devices without requiring the rigorous safety and efficacy testing required for standard device approvals. A humanitarian device is one that is intended to benefit individuals in the treatment and diagnosis of rare diseases or conditions that affect or are manifested in fewer than 4,000 individuals in the United States per year. The goal of the HDE process is to allow the use of specific devices for indications where other alternatives are unavailable. A healthcare provider is responsible for obtaining Institutional Review Board approval before a humanitarian device with an exemption may be administered or implanted. For the NEUROLINK^® System, the Center for Devices and Radiological Health (CDRH) of the FDA determined that, based on the data submitted in the HDE, the NEUROLINK System will not expose recipients to an unreasonable or significant risk of illness or injury. The probable benefit to health from using the device outweighs the risks of illness or injury "For the treatment of individuals with recurrent stroke attributable to atherosclerotic disease refractory to medical therapy in intracranial vessels ranging from 2.5 to 4.5 mm in diameter with greater than or equal to 50% stenosis that are accessible to the stent system".  The FDA issued an approval order on August 9, 2002.

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 transient ischemic attacks are diminished or relieved completely and the risk of stroke, which may include death, 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 a high 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%.

Possible Risks

Risks include restenosis after implantation of the stent (generally uncommon). Non-neurologic complications (e.g., slow heart rate, transient loss of consciousness) may occur during the procedure. 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. In recent studies, the overall postoperative neurologic complication rates have ranged from about 0% to 10%.

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.

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

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 brains' blood supply.

Endarterectomy: 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.

Endovascular coils (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.

Heart failure: This term refers to failure of the heart to adequately pump blood to the rest of the body.  Fatigue, shortness of breath, and fluid overload causing peripheral edema are common signs and symptoms.  The New York Heart Association (NYHA) has classified heart failure into four categories:

Class I:  Symptoms cause no limitation of physical activity. Ordinary physical activity does not lead to undue fatigue, palpitations, or dyspnea
Class II:   Symptoms cause slight limitation of physical activity. The subject is comfortable at rest, but ordinary physical activity results in fatigue, palpitations, or dyspnea
Class III:  Symptoms cause marked limitation of physical activity. The subject is comfortable at rest, but even slight physical activity causes fatigue, palpitations, or dyspnea
Class IV: Symptoms of cardiac insufficiency are present at rest, and discomfort is increased with any physical activity

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, (i.e., anterior, middle and posterior cerebral, vertebrobasilar or basilar).

Left ventricular ejection fraction (LVEF):  This is a measure of the pumping efficiency of the heart.

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.

The following codes for treatments and procedures applicable to this document 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 for those conditions listed in the Position Statement section as not medically necessary.

When services are Investigational and Not Medically Necessary:
For the procedure codes listed above when criteria are not met or for extracranial arteries other than carotid, or when the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.

When services are also Investigational and Not Medically Necessary:

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

When services are Investigational and Not Medically Necessary:
For the procedure and diagnosis codes listed above when criteria are not met or for all other diagnoses not listed, or when the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary (including when specified as intracranial vertebral artery angioplasty and stent placement). 

When services are also Investigational and Not Medically Necessary:

Future ICD-10 coding (effective 10/01/2013)A draft of ICD-10 Coding related to this document, as it might look today, is available for reference and comments at: Appendix 1: Future ICD-10 coding

Peer Reviewed Publications:

1. Alazzaz A, Thornton J, Aletich VA, et al. Intracranial percutaneous angioplasty for arteriosclerotic stenosis. Arch Neurol. 2000; 57(11):1625-1630.
2. Albuquerque FC, Fiorella D, Han P, et al. A reappraisal of angioplasty and stenting for the treatment of vertebral origin stenosis. Neurosurgery. 2003; 53(3):607-616.
3. Barnett HJ, Taylor DW, Eliasziw M, et al. Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. N Engl J Med. 1998; 339(20):1415-1425.
4. Biondi A, Janardhan V, Katz JM, et al. Neuroform stent-assisted coil embolization of wide-neck intracranial aneurysms: strategies in stent deployment and midterm follow-up. Neurosurgery. 2007; 61(3):460-468.
5. Bowser AN, Bandyk DF, Evans A, et al. Outcome of carotid stent-assisted angioplasty versus open surgical repair of recurrent carotid stenosis. J Vascu Surg. 2003; 38(3):432-438.
6. Brahmanandam S, Ding EL, Conte MS, et al. Clinical results of carotid artery stenting compared with carotid endarterectomy. J Vasc Surg. 2008; 47(2):343-349.
7. Brooks WH, McClure RR, Jones MR, et al. Carotid angioplasty and stenting versus carotid endarterectomy for treatment of asymptomatic carotid stenosis: a randomized trial in a community hospital. Neurosurgery. 2004; 54(2):318-325.
8. Brott TG, Brown RD Jr, Meyer FB, et al. Carotid revascularization for prevention of stroke: carotid endarterectomy and carotid artery stenting. Mayo Clinic Proc. September, 2004; 79(9):1197-1208.
9. Brott TG, Hobson RW 2^nd, Howard G, et al.  Stenting versus endarterectomy for treatment of carotid-artery stenosis. N Engl J Med. 2010; 363(1):11-23.
10. Brown MM. Carotid artery stenting – evolution of a technique to rival carotid endarterectomy. Am J Med. 2004; 116(4):273-275.
11. Bush RL, Lin PH, Bianco CC, et al. Carotid artery stenting in a community setting: experience outside of a clinical trial. Ann Vasc Surg. 2003; 17(6):629-634.
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13. CAVATAS Investigators. Endovascular versus surgical treatment in patients with carotid stenosis in the carotid and vertebral artery transluminal angioplasty study (CAVATAS): a randomized trial. Lancet. 2001; 357(9270):1729-1737.
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15. Cloud GC, Crawley F, Clifton A, et al. Vertebral artery origin angioplasty and primary stenting: safety and restenosis rates in a prospective series. J Neurol Neurosurg Psychiatry. 2003; 74(5):586-590.
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20. Dietz A, Berkefeld J, Theron JG, et al. Endovascular treatment of symptomatic carotid stenosis using stent placement: long-term follow-up of patients with a balanced surgical risk/benefit ratio. Stroke. 2001; 32(8):1855-1859.
21. Doerfler A, Becker W, Wanke I, et al. Endovascular treatment of cerebrovascular disease. Curr Opin Neurol. 2004; 17(4):481-487.
22. Eckstein HH, Ringleb P, Allenberg JR, et al. Results of the Stent-Protected Angioplasty versus Carotid Endarterectomy (SPACE) study to treat symptomatic stenoses at 2 years: a multinational, prospective, randomised trial. Lancet Neurol. 2008; 7(10):893-902.
23. Ederle J, Dobson J, Featherstone RL, et al.  Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial.  Lancet. 2010; 375(9719):985-997.
24. Fiorella D, Albuquerque FC, Han P, McDougall CG.  Preliminary experience using the NeuroForm stent for the treatment of cerebral aneurysms.  Neurosurgery. 2004; 54(1):6-17.
25. Fiorella D, Levy EI, Turk AS, et al. US multicenter experience with the wingspan stent system for the treatment of intracranial atheromatous disease: periprocedural results. Stroke. 2007; 38(3):881-887.
26. Fox DJ Jr, Moran CJ, Cross DT 3rd, et al. Long-term outcomes after angioplasty for symptomatic extracranial carotid stenosis in poor surgical candidates. Stroke. 2002; 33(12):2877-2880.
27. Gable DR, Bergamini T, Garrett WV, et al. Intermediate follow up of carotid artery stent placement. Am J Surg. 2003; 185(3):183-187.
28. Gasparis AP, Ricotta L, Cuadra SA, et al. High-risk carotid endarterectomy: fact or fiction. J Vasc Surg. 2003; 37(1):40-46.
29. Gray WA Hopkins LN, Yadav S, et al.  Protected carotid stenting in high-surgical risk patients: the ARCHeR results. J Vasc Surg. 2006; 44(2):258-69.
30. Gray WA, Yadav JS, Verta P et al. The CAPTURE registry: results of carotid stenting with embolic protection in the post approval setting. Catheter Cardiovasc Interv. 2007; 69(3):341-348.
31. Gress DR, Smith WS, Dowd CF, et al. Angioplasty for intracranial symptomatic vertebrobasilar ischemia. Neurosurgery. 2002; 51(1):23-29.
32. Gupta R, Schumacher HC, Mangla S, et al. Urgent endovascular revascularization for symptomatic intracranial atherosclerotic stenosis. Neurology. 2003; 61(12):1729-1735.
33. Gurm HS, Yadav JS, Fayad P et al. Long-term results of carotid stenting versus endarterectomy in high-risk patients. N Engl J Med. 2008; 358(15):1572-1579.
34. Hanel RA, Levy EL, Guterman LR, Hopkins LN.  Intracranial atherosclerotic disease:  common, dangerous and treatable.  Clin Neurosurg. 2005; 52:68-75.
35. Hartmann M, Jansen O.  Angioplasty and stenting of intracranial stenosis.  Curr Opin Neurol. 2005; 18(1):39-45.
36. Higashida RT, Meyers PM.  Intracranial angioplasty and stenting for cerebral atherosclerosis: new treatments are needed!  Neuroradiology. 2006; 48(6):367-372.
37. Higashida RT, Meyers PM, Phatouros CC, et al; Technology Assessment Committees of the American Society of Interventional and Therapeutic Neuroradiology and the Society of Interventional Radiology. Reporting standards for carotid artery angioplasty and stent placement. J Vasc Interv Radiol. 2004; 15(5):421-422.
38. Hobson RW 2^nd. Update on the Carotid Revascularization Endarterectomy versus Stent Trial (CREST) protocol. J Am Coll Surg. 2002; 194(1):S9-S14.
39. Hobson RW 2^nd. Rationale and status of randomized controlled clinical trials in carotid artery stenting. Semin Vasc Surg. 2003a; 16(4):311-316.
40. Hobson RW 2^nd. Carotid Artery Stenting. Surg Clin North Am. 2004a; 84(5):1281–1294.
41. Hobson RW 2^nd, Brott TG, Roubin GS, et al. Closure of the lead-in phase of CREST (Carotid Revascularization Endarterectomy vs. Stenting trial): 30-day and one year analysis. Stroke. 2008; (2):557. 
42. Hobson RW 2^nd, Howard VJ, Roubin GS, et al; CREST Investigators.  Carotid artery stenting is associated with increased complications in octogenarians:  30-day stroke and death rates in the CREST lead-in phase.  J Vasc Surg. 2004b; 40(6):1106-1111.
43. Hobson RW 2^nd, Lal BK, Chaktoura E, et al. Carotid artery stenting: analysis of data for 105 patients at high risk. J Vasc Surg. 2003b; 37:1234-1239.
44. Iyer SS, White CJ, Hopkins LN, et al. Carotid artery revascularization in high-surgical-risk patients using the Carotid WALLSTENT and FilterWire EX/EZ: 1-year outcomes in the BEACH Pivotal Group. J Am Coll Cardiol. 2008; 51(4):427-434.
45. Jordan WD, Alcocer F, Wirthlin DJ, et al. High-risk carotid endarterectomy: Challenges for carotid stent protocols. J Vasc Surg. 2002;35(1):16-22.
46. Kastrup A, Groschel K, Krapf H, et al. Early outcome of carotid angioplasty and stenting with and without cerebral protection devices: a systemic review of the literature. Stroke. 2003; 34(3):813-819.
47. Katzen BT, Criado FJ, Ramee SR, et al. Carotid artery stenting with emboli protection surveillance study: thirty-day results of the CASES-PMS study. Catheter Cardiovasc Interv. 2007; 70(2):316-323.
48. Komotar RJ, Mocco J, Wilson DA, et al.  Current endovascular treatment options for intracranial carotid artery atherosclerosis.  Neurosurg Focus. 2005; 18(1):E5.
49. Lal BK, Hobson RW 2^nd. Treatment of carotid artery disease:  stenting or surgery.  Curr Neurol Neurosci Rep.  2007; 7(1):49-53.
50. Levy EI, Horowitz MB, Koebbe CJ, et al. Transluminal stent-assisted angioplasty of the intracranial vertebrobasilar system for medically refractory, posterior circulation ischemia: early results. Neurosurgery. 2001; 48(6):1215-1223.
51. Luebke T, Aleksic M, Brunkwall J. Meta-analysis of randomized trials comparing carotid endarterectomy and endovascular treatment. Eur J Vasc Endovasc Surg. 2007; 34(4):470-479.
52. Lifante I, Hirsh JA, Selim M, et al. Safety of latest-generation self-expanding stents in patients with NASCET-ineligible severe symptomatic extracranial internal carotid artery stenosis. Arch Neurol. 2004; 61(1):39-43.
53. Lylyk P, Vila JF, Miranda C, et al. Partial aortic obstruction improves cerebral perfusion and clinical symptoms in patients with symptomatic vasospasm. Neurol Res. 2005; 27 Suppl 1:S129-S135.
54. Marks MP, Marcellus ML, Do HM, et al. Intracranial angioplasty without stenting for symptomatic atherosclerotic stenosis: Long-term follow-up. AJNR Am J Neuroradiol. 2005; 26(3):525-530.
55. Mas JL, Chatellier G, Beyssen B, et al. EVA-3S Investigators.  Endarterectomy versus stenting in patients with symptomatic severe carotid stenosis.  N Engl J Med. 2006; 355(16):1660-1671.
56. Mas JL, Trinquart L, Leys D, et al. EVA-3S Investigators. Endarterectomy Versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) trial: results up to 4 years from a randomised, multicentre trial. Lancet Neurol. 2008; 7(10):885-892.
57. McCabe DJ, Pereira AC, Clifton A, et al. Restenosis after carotid angioplasty, stenting or endarterectomy in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS).  Stroke. 2005; 36(2):281-286.
58. Mocco J, Snyder KV, Albuquerque FC, et al. Treatment of intracranial aneurysms with the Enterprise stent: a multicenter registry. J Neurosurg. 2009; 110(1):35-39.
59. Molyneux AJ, Kerr RSC, Birks J, et al.  Risk of recurrent subarachnoid hemorrhage, death or dependence and standardized mortality ratios after clipping or coiling of an intracranial aneurysm in the International Subarachnoid Aneurysm Trial (ISAT): long term follow-up.  Lancet Neurol. 2009; 8(5):427-433.
60. Mukherjee D, Yadav JS. Percutaneous treatment for carotid stenosis. Cardiol Clin. 2002; 20(4):589-597.
61. Murayama Y, Nien YL, Duckwiler G, et al.  Guglielmi detachable coil embolization of cerebral aneurysms:  11 years' experience.  J Neurosurg. 2003; 98(5):959-966.
62. Naylor AR, Bolia A, Abbott RJ, et al. Randomized study of carotid angioplasty and stenting versus carotid endarterectomy: a stopped trial. J Vasc Surg. 1998; 28(2):326-334.
63. Paniagua D, Howell M, Strickman N, et al. Outcomes following extracranial carotid artery stenting in high-risk Patients. J Invasive Cardiol. 2001; 13(5):375-381.
64. Park ST, Kim JK, Yoon KH, et al.  Atherosclerotic carotid stenoses of apical versus body lesions in high-risk carotid stenting patients.  AJNR Am J Neuroradiol. 2010; 31(6):1106-1112.
65. Perler BA. Carotid endarterectomy: the "gold standard" in the endovascular era. J Am Coll Surg. 2002; 194(1 Suppl):S2-8.
66. Pierot L, Cognard C, Ricolfi F, et al; CLARITY Investigators. Immediate anatomic results after the endovascular treatment of ruptured intracranial aneurysms: analysis in the CLARITY Series.  AJNR Am J Neuroradiol. 2010; 31(5):907-911.
67. Piotin M, Blanc R, Spelle L, et al. Stent-assisted coiling of intracranial aneurysms: clinical and angiographic results in 216 consecutive aneurysms. Stroke. 2010; 41(1):110-115.
68. Qureshi AI, Knape C, Maroney M, et al. Multicenter clinical trial of the NexStent coiled sheet stent in the treatment of extracranial carotid artery stenosis: immediate results and late clinical outcomes. J Neurosurg. 2003; 99(2):264-270.
69. Raja PV, Huang J, Germanwala AV, et al. Microsurgical clipping and endovascular coiling of intracranial aneurysms: a critical review of the literature. Neurosurgery. 2008; 62(6):1187-1202; discussion 1202-1203.
70. Reimers B, Schluter M, Castriota F, et al. Routine use of cerebral protection during carotid artery stenting: results of a multi-center registry of 753 patients. Am J Med. 2004; 116(4):217-222.
71. Ringleb PA, Allenberg J, Bruckmann H, et al;  SPACE Collaborative Group. 30 day results from the SPACE trial of stent-protected angioplasty versus carotid endarterectomy in symptomatic patients: a randomized non-inferiority trial.  Lancet.  2006; 368(9543):1239-1247.
72. Ringleb PA, Chatellier G, Hacke W, et al. Safety of endovascular treatment of carotid artery stenosis compared with surgical treatment: a meta-analysis. J Vasc Surg. 2008; 47(2):350-355.
73. Rockman CB, Su W, Lamparello, PJ, et al. A reassessment of carotid endarterectomy in the face of contralateral carotid occlusion: surgical results in symptomatic and asymptomatic patients. J Vasc Surg. 2002; 36(4):668-673.
74. Roubin GS, New G, Iyer SS, et al. Immediate and late clinical outcomes of carotid artery stenting in patients with symptomatic and asymptomatic carotid artery stenosis. Circ. 2001; 103(4):532-537.
75. Shawl FA. Carotid artery stenting: acute and long-term results. Curr Opin Cardiol. 2002; 17(6):671-676.
76. Slovut DP, Olin JW. Fibromuscular dysplasia. N Engl J Med. 2004; 350(18):1862-1871.
77. Spes CH, Schwende A, Beier F, et al. Short- and long-term outcome after carotid artery stenting with neuroprotection: single-center experience within a prospective registry. Clin Res Cardiol. 2007; 96(11):812-821.
78. SSYLVIA Study Investigators.  Stenting of symptomatic atherosclerotic lesions in the vertebral or intracranial arteries (SSYLVIA): study results.  Stroke. 2004; 35(6):1388-1392.
79. Steinbauer MG, Pfister K, Greindl M, et al. Alert for increased long-term follow-up after carotid artery stenting: results of a prospective, randomized, single-center trial of carotid artery stenting vs. carotid endarterectomy. J Vasc Surg. 2008; 48(1):93-98.
80. Stolker JM, Mahoney EM, Safley DM, et al; SAPPHIRE Investigators.  Health-related quality of life following carotid stenting versus endarterectomy: results from the SAPPHIRE (Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy) trial.  JACC Cardiovasc Interv. 2010; 3(5):515-523.
81. Timaran CH, Veith FJ, Rosero EB, et al.  Intracranial hemorrhage after carotid endarterectomy and carotid stenting in the United States in 2005.  J Vasc Surg. 2009; 49(3):623-629.
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Government Agency, Medical Society, and Other Authoritative Publications:

1. Abbott Vascular. Carotid Stenting vs. Surgery of Severe Carotid Artery Disease and Stroke Prevention in Asymptomatic Patients (ACT I). National Library of Medicine (NLM) Identifier: NCT00106938. Last updated May 21, 2010.  Available at: http://clinicaltrials.gov/ct2/show/NCT00106938.  Accessed on April 12, 2011.
2. Barr JD, Connors JJ 3rd, Sacks D, et al. Joint Standards of Practice Committee of the American Society of Interventional and Therapeutic Neuroradiology, the American Society of Neuroradiology, and the Society of Interventional Radiology. Quality improvement guidelines for the performance of cervical carotid angioplasty and stent placement. J Vasc Interv Radiol. 2003; 14(9 Pt 2):S321-S335.
3. Bates ER, Babb JD, Casey DE Jr, et al. American College of Cardiology Foundation Task Force; American Society of Interventional & Therapeutic Neuroradiology; Society for Cardiovascular Angiography and Interventions; Society for Vascular Medicine and Biology; Society for Interventional Radiology (ACCF/SCAI/SVMB/SIR/ASITN). 2007 Clinical Expert Consensus Document on carotid stenting. Vasc Med. 2007; 12(1):35-83.
4. Bettman MA, Katzen BT, Whisnat J, et al. Carotid stenting and angioplasty: a statement for healthcare professionals from the Councils on Cardiovascular Radiology, Stroke, Cardio-Thoracic and Vascular Surgery, Epidemiology and Prevention, and Clinical Cardiology, American Heart Association. Circulation. 1998: 97(1): 121-123.
5. BlueCross BlueShield Association.  Angioplasty and stenting of the cervical carotid artery with distal embolic protection of the cerebral circulation. TEC Assessment, 2004; 19(15).
6. BlueCross BlueShield Association.  Angioplasty and stenting of the cervical carotid artery with embolic protection of the cerebral circulation.  TEC Assessment, 2007; 24(1).
7. Boston Scientific Corporation.  Safety and Efficacy of Neuroform3^™ for Intracranial Aneurysm Treatment (SENAT).  National Library of Medicine (NLM) Identifier: NCT00928265.  Last updated December 17, 2009.  Available at:  http://www.clinicaltrials.gov/ct2/show/NCT00928265?term=stenting+aneurysm&rank=3.  Accessed on February 17, 2011.
8. CaRESS Steering Committee. Carotid revascularization using endarterectomy or stenting systems (CaRESS) phase I clinical trial: one year results.  J Vasc Surg. 2005; 42(2):213-219.
9. Centers for Medicare & Medicaid Services (CMS). Decision memo for Percutaneous Transluminal Angioplasty (PTA) of the Carotid Artery concurrent with Stenting (CAG-00085R3). Medicare Coverage Database. Rockville, MD: CMS; April 30, 2007.  Available at: http://www.cms.gov/medicare-coverage-database/details/nca-details.aspx?NCAId=194&ver=18&NcaName=Percutaneous+Transluminal+Angioplasty+(PTA)+of+the+Carotid+Artery+Concurrent+with+Stenting&DocID=CAG-00085R3&kq=true&bc=gAAAABAAAAAA&. Accessed on April 12, 2011.
10. Centers for Medicare and Medicaid Services.  National Coverage Determination: Carotid Artery Stenting (CAG-CAG-00085R).  Medicare Coverage Database.  Rockville, MD:  CMS; March 17, 2005.  Available at: https://www.cms.gov/medicare-coverage-database/details/nca-details.aspx?NCAId=157&ver=33&NcaName=Carotid+Artery+Stenting&DocID=CAG-00085R&bc=gAAAABAAAAAA&. Accessed on April 12, 2011.
11. Centers for Medicare and Medicaid Services. National Coverage Determination: Vertebral Artery Surgery. NCD #20.1. Medicare Coverage Database.  Rockville, MD:  CMS. Effective date not posted. Available at: http://www.cms.gov/medicare-coverage-database/details/ncd-details.aspx?NCDId=48&ncdver=1&DocID=20.1&bc=gAAAABAAAAAA&. Accessed on April 12, 2011.
12. Centers for Medicare and Medicaid Services.  National Coverage Determination and Decision Memo for Intracranial Stenting and Angioplasty (CAG-00085R5).  Medicare Coverage Database.  Rockville, MD:  CMS; February 14, 2008.  Available at: https://www.cms.gov/medicare-coverage-database/details/nca-details.aspx?NCAId=214&ver=18&NcaName=Intracranial+Stenting+and+Angioplasty&DocID=CAG-00085R5&bc=gAAAABAAAAAA&. Accessed on April 12, 2011.
13. Centers for Medicare and Medicaid Services (CMS). Medicare Coverage Database. Proposed Decision Memo for Percutaneous Transluminal Angioplasty (PTA) of the Carotid Artery Concurrent with Stenting (CAG-00085R7). Medicare Coverage Database.  Rockville, MD:  CMS; September 10, 2009. Available at: https://www.cms.gov/medicare-coverage-database/details/nca-details.aspx?NCAId=230&ver=19&NcaName=Percutaneous+Transluminal+Angioplasty+(PTA)+of+the+Carotid+Artery+Concurrent+with+Stenting&DocID=CAG-00085R7&bc=gAAAABAAAAAA&. Accessed on April 12, 2011.
14. Chaturvedi S, Bruno A, Feasby T, et al. Carotid endarterectomy – an evidence based review. Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology. 2005; 65:794-801.  Available at: http://www.neurology.org/cgi/content/full/65/6/794.  Accessed on April 12, 2011.
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16. Coward LJ, Featherstone RL, Brown MM. Percutaneous transluminal angioplasty and stenting for vertebral artery stenosis.  Cochrane Database of Systematic Reviews 2005, Issue 2. Art. No.: CD000516.
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20. Hobson RW 2nd, Mackey WC, Ascher E, et al. Society for Vascular Surgery. Management of atherosclerotic carotid artery disease: clinical practice guidelines of the Society for Vascular Surgery. J Vasc Surg. 2008; 48(2):480-486.  Available at:   http://endovasc.org/guidelines/guidelines/Carotid-CPG-090508%20JVS.pdf.  Accessed on April 12, 2011.
21. Liapis CD, Bell PR, Mikhailidis D, et al. ESVS Guidelines Collaborators. ESVS guidelines. Invasive treatment for carotid stenosis: indications, techniques. Eur J Vasc Endovasc Surg. 2009; 37(4 Suppl):1-19.
22. Mazighi M, Tanasescu R, Ducrocq X, et al. Prospective study of asymptomatic atherothrombotic intracranial stenoses: The GESICA study.  Neurology. 2006; 66(8):1187-1191.
23. Medical University of South Carolina. Stenting vs. Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS).   National Library of Medicine (NLM) Identifier:  NCT00576693.  Last updated March 25, 2010.  Available at:  http://clinicaltrials.gov/ct2/show/study/NCT00576693?term=SAMMPRIS&rank=1#locn.  Accessed on February 17, 2011.
24. Micrus Endovascular Corporation.  VISSIT Intracranial Stent Study for Ischemic Therapy.  National Library of Medicine (NLM) Identifier:  NCT00816166.  Last updated December 30, 2008.  Available at:  http://clinicaltrials.gov/ct2/show/NCT00816166?term=VISSIT&rank=1.  Accessed on February 17, 2011.
25. Myers PM, Schumacher HC, Higashida RT, et al. Indications for the performance of intracranial endovascular neurointerventional procedures: A scientific statement from the American Heart Association 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. Circulation. 2009; 119(16):2235-2249.
26. National Institute for Clinical Excellence (NICE). Carotid artery stent placement for symptomatic extracranial carotid stenosis: Interventional Procedure Guidance: 389.   London, UK: NICE; April 2011. Available at: http://www.nice.org.uk/nicemedia/live/11135/54273/54273.pdf.  Accessed on April 12, 2011.
27. National Institute for Clinical Excellence (NICE). Carotid artery stent placement for asymptomatic extracranial carotid stenosis:  Interventional Procedure Guidance: 388.  London, UK: NICE; April 2011.  Available at:  http://www.nice.org.uk/nicemedia/live/13026/54241/54241.pdf.  Accessed on May 18, 2011.
28. National Institute for Health and Clinical Excellence (NICE). Endovascular stent insertion for intracranial atherosclerotic disease. Interventional Procedure Guidance 233. London, UK: NICE; October 2007.  Available at:  http://www.nice.org.uk/nicemedia/live/11356/38009/38009.pdf.  Accessed on April 27, 2011.
29. Sacco RL, Adams R, Albers G, et al.  AHA/ASA Guidelines.  Guidelines for Prevention of Stroke in Patients With Ischemic Stroke or Transient Ischemic Attack  A statement for healthcare professionals from the American Heart Association/American Stroke Association Council on Stroke: Co-sponsored by the Council on Cardiovascular Radiology and Intervention: The American Academy of Neurology affirms the value of this guideline  Stroke. 2006; 37(2):577-617.
30. Stenting and angioplasty with protection in patients at high risk for endarterectomy: 3-year results (SAPPHIRE: 3 year results). ACC Cardiosource Review Journal. 2008; 17.
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1. American Heart Association. Available at: http://www.amhrt.org/presenter.jhtml?identifier=1200000. Accessed on April 12, 2011. 
2. American Stroke Association.  Available at:  http://www.strokeassociation.org/presenter.jhtml?identifier=1200037. Accessed on April 12, 2011. 

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
NEUROLINK® System
Pipeline Embolization Device™
Protege® GPS™
Protege® RX Carotid Stent System
Wingspan Stent System™ with Gateway™ PTA Balloon Catheter

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.