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Carotid Artery Stenting
Introduction
The concept of endovascular therapy for treatment of carotid artery stenosis was first proposed in 1977 by Mathias, who reported successful results of carotid artery angioplasty using peripheral arterial angioplasty technology. , Balloon-expandable stents for the treatment of cerebrovascular disease were introduced 10 years later, with successful deployment of carotid artery stents in two patients with aneurysms and stenosis of the distal cervical carotid artery. This experience was subsequently adapted for the use of treating high-grade symptomatic carotid artery stenosis, although the initial enthusiasm was dampened by high perioperative stroke rates, 6% to 9%.
In 1990, Theron et al. published their technique using cerebral protection. This led to the development of embolic protection devices (EPDs), which drastically reduced stroke rates and revitalized interest in endovascular therapy for carotid artery stenosis. More recently, transcarotid artery revascularization (TCAR) using flow reversal has been introduced as an alternative with favorable outcomes, also reinvigorating carotid artery stenting in certain populations
Transfemoral Carotid Stent (TF-CAS) Trials
Multiple randomized controlled trials (RCTs) have compared outcomes after TF-CAS versus the “gold standard” of carotid endarterectomy (CEA) ( Table 94.1 ). Several of these studies found TF-CAS to be noninferior to CEA. , However, the EVA-3S , and SPACE , trials showed higher rates of perioperative stroke/death with TF-CAS. Similarly, in CREST, patients undergoing TF-CAS had higher rates of periprocedural stroke, although rates of periprocedural myocardial infarction (MI) were lower. , These studies are criticized for limited generalizability, pre-dating modern best medical therapy, and often unbalanced training requirements between interventionalists performing stenting versus CEA.
TABLE 94.1
Summary of Major Completed Randomized Controlled Trials Comparing Transfemoral Carotid Artery Stenting (TF-CAS) vs. Carotid Endarterectomy (CEA)
| Trial | Publication Date | Sample Size | Carotid Stenosis Criteria | Study Design | EPD Use for TF-CAS | Primary Outcome | Results TF-CAS vs. CEA | Conclusion |
|---|---|---|---|---|---|---|---|---|
| SAPPHIRE , | 2004, 2008 | 334 | ≥50% symptomaticor ≥80% asymptomatic | Noninferiority RCT United States |
97% | Composite death, stroke, MI within 30 days or ipsilateral stroke up to 1 year | 1 year: 12.2% vs. 20.1% 3 years: 24.6% TF-CAS vs. 26.9% |
TF-CAS noninferior to CEA |
| EVA-3S , | 2006, 2008 | 527 | >60% symptomatic carotid artery stenosis | Noninferiority RCT Europe |
92% | Any stroke or death within 30 days | 30 days: 9.6% vs. 3.9% 6 months: 11.7% vs. 6.1% 4 years: 11.1% vs. 6.2% |
Worse periprocedural stroke/death outcomes with TF-CAS |
| SPACE , | 2006, 2008 | 1200 | ≥70% symptomatic carotid stenosis | Noninferiority RCT Europe |
27% | Ipsilateral stroke or death within 30 days | 30 days: 6.8% vs. 6.3% 2 years: 9.5% vs. 8.8% |
Higher risk of periprocedural adverse events with TF-CAS |
| ICSS , | 2010, 2015 | 1713 | >50% symptomatic carotid artery stenosis | Noninferiority RCT Europe |
72% | 3-year fatal or disabling stroke in any territory | 120 days: 8.5% vs. 5.2% 4.2 years: 6.4% vs. 6.5% |
Long-term risk of disabling stroke is similar for TF-CAS and CEA |
| CREST , | 2010, 2016 | 2502 | Symptomatic or asymptomatic carotid artery stenosis ≥70% (ultrasound) or symptomatic ≥50% (angiography) | Noninferiority RCT North America |
96% | Composite stroke, MI, or death within 30 days or ipsilateral stroke within 4 years | 4 years: 7.2% vs. 6.8% 10 years: 11.8% vs. 9.9% |
No significant long-term differences for TF-CAS vs. CEA in composite endpoint or risk of stroke |
| ACT-I | 2016 | 1453 | >80% asymptomatic carotid stenosis | Noninferiority RCT United States |
100% | Composite of death, stroke, or MI within 30 days or ipsilateral stroke within 1 year | 30 days: 2.9% vs. 1.7% 1 year: 3.8% vs. 3.4% |
TF-CAS not inferior to CEA for composite endpoint |
CAS/CEA, carotid artery stenting (CAS)/carotid endarterectomy (CEA); CREST, Carotid Revascularization Endarterectomy Versus Stenting Trial; ICSS, International Carotid Stenting Study (ICSS); MI, myocardial infarction; RCT, randomized controlled trials; SAPPHIRE, Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy; SPACE, the Stent-Supported Percutaneous Angioplasty of the Carotid Artery Versus Endarterectomy.
Transcarotid Artery Revascularization (TCAR) Trials
No large, randomized controlled trials have to date been performed comparing TCAR to TF-CAS or CEA. However, clinical trial data and prospectively maintained data registries have shown promising results. The Safety and Efficacy Study for Reverse Flow Used During Carotid Artery Stenting Procedure (ROADSTER) trial overall perioperative stroke rate was 1.4%. Although not designed as a comparative effectiveness trial, the reported perioperative stroke rates were lower than any prior prospective multicenter clinical trial of TF-CAS. One-year data from the ROADSTER trial were also favorable, with a 0.6% incidence of ipsilateral stroke and 4.2% rate of death, none neurologic in etiology. Based on these findings, the authors suggest that TCAR offers a safe and durable revascularization option for patients who are deemed to be at high risk for CEA.
Following ROADSTER, data from all TCAR procedures performed in the US were captured in the SVS Vascular Quality Initiative (VQI) TCAR Surveillance Project registry. Retrospective analyses of these data demonstrated that despite TCAR being performed in higher risk patients, the in-hospital rates of stroke/death were similar for TCAR compared to CEA (1.6% vs. 1.4%, P = 0.33), but the rate of cranial nerve injury was lower (0.6% vs. 1.8%, P < 0.001). TCAR had a lower rate of in-hospital transient ischemic attack (TIA), stroke, and death compared to TF-CAS (2.2% vs. 3.8%, P = 0.04) that persisted after multivariable adjustment (odds ratio 2.1 [95% CI 1.08 to 4.08], P = 0.03). At 1 year postoperatively, TCAR was associated with a lower risk of ipsilateral stroke or death compared to TF-CAS (5.1% vs. 9.6%, hazard ratio 0.52 [95% CI 0.41 to 0.66], P < 0.001). Taken together, TCAR is purported to have comparable outcomes to CEA and improved outcomes compared to TF-CAS based on non-randomized data.
Current Carotid Stent Guidelines
Because of the perceived higher periprocedural risk of stroke with TF-CAS compared with CEA based on results from RCTs, the indications for carotid stenting according to the current guidelines for use of TF-CAS for treating carotid artery stenosis are limited. A consensus supports the use of TF-CAS in symptomatic patients with high-grade stenoses who are deemed too high medical risk to undergo open surgery. The use of TF-CAS for low or moderate risk patients without prior neck radiation or surgery, or those who have asymptomatic carotid artery disease, is less well supported. One report supports the use of TF-CAS in lower medical risk patients with higher anatomic risk factors for CEA such as restenosis or neck radiation. However, many experts cite concerns about long-term viability of TF-CAS. As such, Societal guidelines addressing the appropriate use of TF-CAS are cautious ( Tables 94.2 and 94.3 ). The SVS guidelines note that asymptomatic patients who are deemed too high risk for CEA should receive medical therapy rather than carotid stenting. Most existing guidelines were published prior to the introduction of TCAR, so the role for this technique has not been defined.
TABLE 94.2
Carotid Treatment Guidelines for Patients with Symptomatic Carotid Artery Stenosis
Adapted from Paraskevas KI, Mikhailidis DP, Veith FJ. Comparison of the five 2011 guidelines for the treatment of carotid stenosis. J Vasc Surg . 2012;55(5):1504–1508.
| Society | Year | Recommendation | Strength |
|---|---|---|---|
| ACC/AHA | 2011 | 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%. | Class I; level of evidence B |
| Among patients with symptomatic severe stenosis (≥70%) in whom the stenosis is difficult to access surgically, medical conditions are present that greatly increase the risk for surgery, or when other specific circumstances exist, such as radiation-induced stenosis or restenosis after CEA, CAS may be considered. | Class IIb; level of evidence B | ||
| CAS in the above setting is reasonable when performed by operators with established periprocedural morbidity and mortality rates of 4%–6%, similar to those observed in trials of CEA and CAS. | Class IIa; level of evidence B | ||
| SVS | 2011 | In most patients with carotid stenosis who are candidates for intervention, CEA is preferred to CAS for reduction of all-cause and periprocedural death. | Grade I; level of evidence B |
| CAS is preferred over CEA in symptomatic patients with ≥50% stenosis and tracheal stoma, situations where local tissues are scarred and fibrotic from prior ipsilateral surgery or external beam radiotherapy, prior cranial nerve injury, and lesions that extend proximal to the clavicle or distal to the C2 vertebral body. | Grade II; level of evidence B | ||
| CAS is preferred over CEA in symptomatic patients with ≥50% stenosis and severe uncorrectable coronary artery disease, congestive heart failure, or chronic obstructive pulmonary disease. | Grade II; level of evidence C | ||
| ESC | 2011 | In patients with symptomatic 70%–99% stenosis of the internal carotid artery, CEA is recommended for the prevention of recurrent stroke. | Class I; level of evidence A |
| In symptomatic patients at high surgical risk requiring revascularization, CAS should be considered as an alternative to CEA. | Class IIa; level of evidence B | ||
| In symptomatic patients requiring carotid revascularization, CAS may be considered as an alternative to CEA in high-volume centers with documented death or stroke rate <6%. | Class IIb; level of evidence B | ||
| ESVS | 2017 | It is recommended that most patients who have suffered carotid territory symptoms within the preceding 6 months and who are aged > 70 years and who have 50%–99% stenoses should be treated by carotid endarterectomy, rather than carotid stenting | Class I; level of evidence A |
| When revascularization is indicated in patients who have suffered carotid territory symptoms within the preceding 6 months and who are aged < 70 years, carotid stenting may be considered an alternative to endarterectomy, provided the documented procedural death/stroke rate is < 6% | Class IIB; level of evidence A |
Note: CAS (carotid artery stenting) refers to transfemoral CAS for the purposes of the 2011 guidelines, as transcarotid artery revascularization (TCAR) was not commercially available at that time.
ACC/AHA, American College of Cardiology/American Heart Association; CAS, carotid artery stenting; CEA, carotid endarterectomy; ESC, European Society of Cardiology; SVS, Society for Vascular Surgery; ESVS, European Society for Vascular Surgery
TABLE 94.3
Carotid Treatment Guidelines for Patients with Asymptomatic Carotid Artery Stenosis
Adapted from Paraskevas KI, Mikhailidis DP, Veith FJ. Comparison of the five 2011 guidelines for the treatment of carotid stenosis. J Vasc Surg . 2012;55(5):1504–1508.
| Society | Year | Recommendation | Strength |
|---|---|---|---|
| ACC/AHA | 2011 | Prophylactic CAS might be considered in highly selected patients with asymptomatic carotid stenosis (minimum 60% by angiography, 70% by validated Doppler ultrasound), but its effectiveness compared with medical therapy alone in this situation is not well established. | Class IIb; level of evidence B |
| SVS | 2011 | Neurologically asymptomatic patients with ≥60% diameter stenosis should be considered for CEA for reduction of long-term risk of stroke, provided the patient has a 3- to 5-year life expectancy and perioperative stroke/death rates can be ≤3%. | Class I; level of evidence A |
| There are insufficient data to recommend CAS as primary therapy for neurologically asymptomatic patients with 70% to 99% diameter stenosis. Data from CREST suggest that in properly selected asymptomatic patients, CAS is equivalent to CEA in the hands of experienced interventionalists. | Grade II; level of evidence B | ||
| ESC | 2011 | In asymptomatic patients with carotid artery stenosis ≥60%, CEA should be considered as long as the perioperative stroke and death rate for procedures performed by the surgical team is <3% and the patient’s life expectancy exceeds 5 years. | Class IIa; level of evidence A |
| In asymptomatic patients with an indication for carotid revascularization, CAS may be considered as an alternative to CEA in high-volume centers with documented death or stroke rate <3%. | Class IIa; level of evidence B | ||
| ESVS | 2017 | In “average surgical risk” patients with an asymptomatic 60%–99% stenosis in the presence of one or more imaging characteristics that may be associated with an increased risk of late ipsilateral stroke, carotid stenting may be an alternative to carotid endarterectomy, provided documented perioperative stroke/death rates are < 3% and the patient’s life expectancy exceeds 5 years | Class IIb; level of evidence B |
| Carotid stenting may be considered in selected asymptomatic patients who have been deemed by the multidisciplinary team to be “high risk for surgery” and who have an asymptomatic 60%–99% stenosis in the presence of one or more imaging characteristics that may be associated with an increased risk of late ipsilateral stroke, provided documented procedural risks are < 3% and the patient’s life expectancy exceeds 5 years | Class IIb; level of evidence B |
Note: CAS (carotid artery stenting) refers to transfemoral CAS for the purposes of the 2011 guidelines, as transcarotid artery revascularization (TCAR) was not commercially available at that time.
ACC/AHA, American College of Cardiology/American Heart Association; CAS, carotid artery stenting; CEA, carotid endarterectomy; ESC, European Society of Cardiology; SVS, Society for Vascular Surgery; ESVS, European Society for Vascular Surgery.
Patient Selection
TF-CAS is currently supported only for use in a group of highly select patients meeting appropriate diagnostic criteria. According to CMS criteria ( Table 94.4 ), all patients must have a diagnosis of high-grade carotid artery stenosis based on duplex ultrasound or carotid artery angiography; if the diagnosis is based on duplex findings, the degree of stenosis must be confirmed via angiography at the time of the procedure prior to stenting. Patients must also be symptomatic and/or at high risk for open surgical intervention, as determined by the presence of either a significant medical comorbidity (see Table 94.4 ), prior neck radiation therapy or a prior ipsilateral CEA. Other considerations when selecting a patient who might be appropriate for stenting are noted below.
TABLE 94.4
Medicare Decision Summary for Carotid Artery Stenting
| Carotid artery stenting with embolic protection is reasonable and necessary for the following: |
|
|
|
| Patients who are at high risk for CEA include those with any of the following: |
|
|
|
|
|
|
|
|
CEA, carotid endarterectomy; IDE, Investigational Device Exemption.
Age
Given the less invasive nature of carotid artery stenting, the use of TF-CAS for treating elderly patients with carotid artery stenosis was initially considered one of the main indications. Unexpectedly, data demonstrated that the opposite was true; the risk of an adverse event with TF-CAS was significantly higher than that with CEA in older patients. In post hoc analysis of the SPACE trial, ipsilateral stroke or death after TF-CAS occurred in 2.7% of patients 68 years or younger versus 10.8% in patients >68 years, whereas outcomes after CEA were not significantly different. Similarly, an analysis of CREST demonstrated the risk of adverse events increased by 1.77 times per 10-year incremental increase in age after TF-CAS but was stable regardless of age after CEA. These findings are confirmed by a meta-analysis of 4754 patients enrolled in CREST and the Carotid Stenting Trialists’ Collaboration trials, which demonstrated a significant pattern of increased periprocedural risk with increasing age in patients assigned to TF-CAS versus CEA starting at 70 years and older ( P < 0.001).
Population database analyses examining the effects of age on adverse events after TF-CAS and CEA report similar findings. Data from the SVS Vascular Registry demonstrated inferior 30-day composite outcomes in patients >65 years undergoing TF-CAS, regardless of symptom status. Data from the Nationwide Inpatient Sample demonstrated worse stroke rates and cardiac complications among patients >70 years who underwent TF-CAS.
In a Cochrane Database of Systematic Review from 2012 including 16 trials, 7572 patients supported these findings; the overall risk of perioperative death or any stroke was significantly higher for TF-CAS versus CEA among patients >70 years (OR 2.20, 95% confidence interval [CI] 1.47 to 3.29) but not significantly different for younger patients (OR 1.16, 95% CI 0.80). These data suggest that TF-CAS should be reserved for younger patients.
It is theorized that the higher stroke rate is related to the higher prevalence of aortic arch and proximal common carotid artery atheroma in this population. TCAR with flow reversal avoids this source and has been shown in small series to be equally as safe among high-risk patients regardless of age. Furthermore, recent registry data from the VQI compared outcomes following CEA, TF-CAS, and TCAR and found no difference in outcomes following TCAR in patients ≤70, 71–79, or ≥80 years of age. The same analysis also found lower rates of stroke following TCAR compared to TF-CAS in patients aged ≥80 years. Based on these limited data, one of the current published indications for TCAR is age ≥75 years.
Gender
There are well-described differences in outcomes between women and men with carotid disease intervention, however the gender-specific effects on outcomes after carotid artery stenting are less clear. A secondary analysis of CREST data suggested that the perioperative risk of an adverse event was higher in women who underwent TF-CAS versus those who underwent CEA (6.8% vs. 3.8%) but similar among men regardless of approach (4.3% vs. 4.9%). , These findings were attributable to an increased stroke rate in females undergoing TF-CAS (5.5% vs. 2.2%). In contrast, a meta-analysis of patients enrolled in the European Carotid Stenting Trialists Collaboration (CSTC), including the EVA-3S, SPACE, and ICSS trials, demonstrated equivalent outcomes with TF-CAS and CEA for both males and females. A subsequent meta-analysis from CREST, the CSTC, and the CAVATAS trial supported the latter conclusion that gender had no real effect on the risks following either treatment.
Interestingly, observational data evaluating the embolic debris captured in EPDs after TF-CAS suggested that symptomatic women have a greater mean debris particle size compared with asymptomatic women, whereas the difference in debris size after carotid stenting is not statistically different between symptomatic versus asymptomatic men. Accordingly, CREST data suggest that the main difference in stroke/death rates occurred among symptomatic women (7.5% vs. 2.7% in TF-CAS vs. CEA, respectively). It should be noted that symptomatic women may have a different plaque morphology with greater embolic potential than their asymptomatic counterparts, which could predispose them to higher perioperative stroke risk with TF-CAS. The association of sex with outcomes after TCAR has not yet been described.
Hostile Neck
Patients with prior neck surgery or radiation should be considered for carotid artery stenting to reduce risks of cranial nerve injury. Based on a systemic review of available literature through 2012, Kasivisvanathan et al. reported that TF-CAS is technically feasible in post-radiotherapy carotid stenosis and has a similar safety profile to that of nonirradiated necks when performed at a high-volume center. Furthermore, in a meta-analysis of 27 articles including 533 patients, Fokkema et al. demonstrated that the perioperative risk of any cerebrovascular adverse event was similar for TF-CAS versus CEA (3.9% vs. 3.5%), but the risk of cranial nerve injury was substantially higher after CEA (9.2% vs. 0%). Societal guidelines now include the presence of neck scarring and fibrosis from prior ipsilateral surgery such as radical neck dissection or prior CEA or external beam radiotherapy as an indication for considering TF-CAS over CEA.
A hostile neck, including restenosis post-CEA, cervical spine immobility, and history of either neck irradiation or radical neck dissection, was one indication for TCAR in the ROADSTER trial, with 36% of patients having these anatomic constraints. Despite the necessary common carotid dissection, only one transient cranial nerve injury (0.7%) occurred in the cohort.
Restenosis
Based on data from CREST, approximately 6% of patients undergoing TF-CAS or CEA will demonstrate restenosis by 2 years postoperatively (see below). Data from the Vascular Quality Initiative suggest that TF-CAS after prior CEA or TF-CAS is safe; estimated 30-day risk of stroke is 1.4%. More recently, institutional data reporting outcomes following TCAR for restenosis showed a 30-day stroke risk of zero%. However, the clinical significance of restenosis, and indications for intervention, as well as the associated risks of adverse events after carotid artery stenting in patients with prior carotid revascularization, are currently unclear. At this time, we recommend that only patients with severe restenosis be considered for TF-CAS or TCAR, and those procedures should be performed by an expert at an institution with substantial experience. ,
Contraindications
Absolute contraindications to carotid artery stenting include active infection, inability to gain vascular access, and inability for the patient to tolerate antiplatelet therapy. Active infection confers a substantial risk of stent infection and should be avoided in all cases. Access difficulties can be minimized by using different approaches as indicated based on the patient’s history, including femoral, brachial, or transcervical (see below). If none of these options are feasible, CEA should be considered. Dual antiplatelet therapy is essential to minimize the risks of acute stent thrombosis and/or embolization in the perioperative period, although the duration of therapy is controversial. For the TCAR procedure, bilateral femoral vein occlusions and common carotid artery disease are prohibitive as they preclude use of flow reversal and transcervical carotid access, respectively.
Relative contraindications include older age (TF-CAS only), the presence of a circumferential carotid plaque with severe calcification, severe carotid artery tortuosity (two 90-degree angles), near occlusion of the carotid artery (i.e., string sign), and significant aortic arch tortuosity or calcification (TF-CAS). The inability to deploy a cerebral protection device is also a relative contraindication to TF-CAS, although this can be circumvented by using TCAR with flow reversal (see section on “Neuroprotection” later in this chapter). The high rate of periprocedural stroke noted with TF-CAS in the European RCTs is largely attributed to variable use of EPDs. As such, the use of EPDs is now considered standard of care in the deployment of a transfemoral carotid stent.
Anatomic Considerations
Anatomic factors can influence outcomes after carotid artery stenting. A comprehensive understanding of patient anatomy can help with appropriate selection and operative planning.
Aortic Arch Pathology
Aortic arch morphology can be classified into three different types depending on the position of the takeoff of the great vessels ( Fig. 94.1 ). In type I aortic arches, the great vessels arise at or above the same horizontal place as the outer curvature of the arch. In type II aortic arches, the origin of the innominate artery lies between the horizontal plane of the inner and outer curve of the aortic arch. In type III aortic arches, the innominate artery lies below the horizontal plane of the inner curvature of the aortic arch. As the takeoff moves more inferiorly (i.e., type II and type III configurations), vessel selection and the manipulation of sheath, balloon, and stent delivery system become more difficult. Reverse curvature catheters may be helpful for carotid cannulation in these scenarios. Type III aortic arch morphologies are particularly challenging and can lead to a higher risk of embolic events due to repeated and/or prolonged wire, catheter, and sheath manipulation leading to the disruption of aortic plaques.
Aortic arches with extensive aortic wall atheroma and irregularities (i.e., shaggy aorta) and those with severe calcification (eggshell aorta) may also increase the technical complexity of TF-CAS and subsequently increase the patient’s risk of stroke ( Fig. 94.2 ). Shaggy aortas are composed of multiple atheromas that can break off upon contact with a wire or catheter, leading to atheroembolism. An eggshell aorta has poor compliance and is at risk for dissection or embolism that can similarly lead to devastating neurologic or visceral sequelae. The stiffness of an eggshell aorta can also make wire and catheter torqueability a challenge, leading to difficulty manipulating the stent delivery system into appropriate position within the target lesion. For patients with complex and/or high-risk aortic arch anatomy that have an indication for carotid artery stenting, TCAR should be considered over TF-CAS. TCAR completely avoids the manipulation of the aortic arch via direct transcervical CCA cannulation.
Carotid Artery Morphology
Carotid artery tortuosity and plaque burden can greatly affect the deliverability of both the EPD and the stent delivery system into the appropriate positions. Data from the EVA-3S trial suggests that the internal carotid artery (ICA)-CCA angulation of >60 degrees increases the relative risk of death or stroke after TF-CAS by 4.96 times (95% CI 2.29 to 10.74). ICAs that are particularly tortuous, especially distally, can cause difficulty positioning the EPD sufficiently far enough away from the lesion to allow for stent deployment. Internal carotid arteries with severe angulation at the distal end of the stenotic lesion can cause flow limitations, or kinking due to significant changes in carotid morphology after stent deployment ( Fig. 94.3 ). Tortuous vessels are also more prone to vasospasm at the end of the procedure.
Carotid arteries with circumferential plaque burden and atheroma are noncompliant and thus can be difficult to access and can increase the risk of embolization during manipulation ( Fig. 94.4 ). In addition, highly stenotic lesions with only a small area of flow (i.e., string sign; Fig. 94.5 ) may make stent delivery difficult and can result in inadequate stent expansion after deployment and subsequent early restenosis due to recoiling.
Plaque Morphology
Both qualitative and quantitative aspects of carotid artery plaque morphology play a role in determining carotid artery stenting outcomes. In one meta-analysis, ICA stenoses >10 mm in length were associated with a 2.36 (95% CI 1.28 to 3.38) increased risk of death or stroke after TF-CAS compared to shorter lesions. Data from CREST showed that in patients with longer lesion lengths (≥12.85 mm), the risk of perioperative stroke or death was significantly higher for TF-CAS than CEA (OR 3.42; 95% CI 1.19 to 9.78).
Carotid plaque echolucency, as assessed by duplex ultrasonography, has also been shown to increase the risk of stroke in TF-CAS. , Unfortunately, user variability results in poor reproducibility and reliability, and as such plaque morphology characteristics are not standardly used for risk-stratifying patients.
Contralateral Carotid Artery Occlusion
The presence of contralateral carotid artery occlusion should not influence the decision to perform a carotid stent. A subgroup analysis of 3137 patients undergoing TF-CAS who were enrolled in a German Carotid Artery Stent registry (ALKK-CAS) demonstrated a low rate of periprocedural death or major strokes among patients with contralateral carotid occlusion versus those without (1.6% vs. 1.4%). Separate retrospective reviews of in-hospital data from two institutions similarly demonstrated both TF-CAS and CEA can both be performed with good perioperative results and acceptable midterm (approximately 2-year) mortality in patients with carotid artery stenosis and contralateral carotid artery occlusion. , A recent retrospective analysis from the SVS VQI demonstrated similar rates of in-hospital stroke among patients undergoing TCAR with a contralateral carotid artery occlusion compared to those with a patent contralateral carotid artery. Notably, the risk of in-hospital stroke was higher for symptomatic patients with a history of stroke undergoing TCAR with a contralateral carotid artery occlusion. Current CMS guidelines cite contralateral carotid artery occlusion as one of the indications for carotid artery stenting, although this is not universally accepted as a high risk factor in the vascular surgical community.
Preoperative Considerations
Preoperative Imaging
Per CMS requirements, all patients require proof of diagnosis of carotid artery stenosis using angiography prior to stent placement. This can occur either preoperatively or intraoperatively, as long as the patient has appropriate duplex ultrasound imaging to support a diagnosis of high-grade carotid artery stenosis. Duplex ultrasound allows for a comprehensive evaluation of extracranial anatomy and the hemodynamic significance of the CCA, ICA, and external carotid artery (ECA) lesions in most patients. In patients in which duplex ultrasound findings are inconclusive or unclear, magnetic resonance imaging or computed tomographic angiography (CTA) may be helpful. CTA specifically can be helpful in patients in whom carotid plaque morphology or extent is unclear and can be used to measure the diameter of the CCA and the ICA to allow for preoperative planning of stent sizing, and to ensure that the patient meets the anatomic requirements.
Timing of Intervention After Acute Stroke
Reported experience on the appropriate timing for carotid revascularization after an acute stroke largely supports CEA over carotid artery stenting. Data from a subgroup analysis of pooled data from two RCTs performed by the Carotid Endarterectomy Trialists Collaboration suggest that CEA confers maximum benefit if performed within 14 days of a neurologic event, assuming the patient’s symptoms have stabilized and he/she is not severely disabled. An analysis of pooled dated from the EVA-3S, SPACE, and ICSS trials demonstrated that the risk of stroke or death with TF-CAS compared with CEA was highest among patients treated within seven days of symptoms. The Carotid Acculink/Accunet Post-Approval Trial to Uncover Unanticipated or Rare Events (CAPTURE) registry also reported worse outcomes among patients undergoing TF-CAS within zero to 13 days of symptom onset, with an odds ratio of having 30-day complications of 2.52 (95% CI 1.33 to 4.78). Most recently, the CSTC performed a pooled analysis of data from four randomized trials found that patients treated with TF-CAS within 7 days of symptom onset had a significantly higher risk of stroke or death compared to patients treated with CEA (8.3% vs. 1.3%). This finding persisted among interventions performed after 7 days (7.1% vs. 3.6%). There are no data reporting outcomes after TCAR in a large cohort of recently symptomatic patients, especially within the first 2 weeks of symptom onset. Based on available date, the 2017 ESVS guidelines, and the SVS guidelines, recommend carotid revascularization within 14 days of symptom onset when appropriate, and support CEA over carotid stenting. ,
Technique
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