Trials and Frontiers in Carotid Endarterectomy and Stenting

Risks of Expanded Medicare Coverage of Carotid Artery Stenting

This Viewpoint describes the potential harms associated with increased coverage of carotid artery stenting by the Centers for Medicare & Medicaid Services.

Carotid artery revascularization using second generation stents versus surgery: a meta-analysis of clinical outcomes

INTRODUCTION

Meta-analyses and emerging randomized data indicate that second-generation ('mesh') carotid stents (SGS) may improve outcomes versus conventional (single-layer) stents but clinically-relevant differences in individual SGS-type performance have been identified. No comparisons exist for SGS versus carotid endarterectomy (CEA).

EVIDENCE ACQUISITION

Thirty-day death (D), stroke (S), myocardial infarction (M), and 12-month ipsilateral stroke and restenosis in SGS studies were meta-analyzed (random effect model) against CEA outcomes. Eligible studies were identified through PubMed/EMBASE/COCHRANE. Forest plots were formed for absolute adverse evet risk in individual studies and for relative outcomes with each SGS deign versus contemporary CEA outcomes as reference. Meta-regression was performed to identify potential modifiers of treatment modality effect.

EVIDENCE SYNTHESIS

Data were extracted from 103,642 patients in 25 studies (14 SGS-treated, 41% symptomatic; nine randomized controlled trial (RCT)-CEA-treated, 37% symptomatic; and two Vascular Quality Initiative (VQI)-CEA-treated, 23% symptomatic). Casper/Roadsaver and CGuard significantly reduced DSM versus RCT-CEA (-2.70% and -2.95%, P<0.001 for both) and versus VQI-CEA (-1.11% and -1.36%, P<0.001 for both). Gore stent 30-day DSM was similar to RCT-CEA (P=0.581) but increased against VQI-CEA (+2.38%, P=0.033). At 12 months, Casper/Roadsaver ipsilateral stroke rate was lower than RCT-CEA (-0.75%, P=0.026) and similar to VQI-CEA (P=0.584). Restenosis with Casper/Roadsaver was +4.18% vs. RCT-CEA and +4.83% vs. VQI-CEA (P=0.005, P<0.001). CGuard 12-month ipsilateral stroke rate was similar to VQI-CEA (P=0.850) and reduced versus RCT-CEA (-0.63%, P=0.030); restenosis was reduced respectively by -0.26% and -0.63% (P=0.033, P<0.001). Twelve-month Gore stent outcomes were overall inferior to surgery.

CONCLUSIONS

Meta-analytic integration of available clinical data indicates: 1) reduction in stroke but increased restenosis rate with Casper/Roadsaver, and 2) reduction in both stroke and restenosis with CGuard MicroNET-covered stent against contemporary CEA outcomes at 30 days and 12 months used as a reference. This may inform clinical practice in anticipation of large-scale randomized trials powered for low clinical event rates (PROSPERO-CRD42022339789).

Effects of plaque characteristics and artery hemodynamics on the residual stenosis after carotid artery stenting

OBJECTIVE

Carotid artery stenting (CAS) has become an alternative strategy to carotid endarterectomy for carotid artery stenosis. Residual stenosis was an independent risk factor for restenosis, with the latter affecting the long-term outcomes of CAS. This multicenter study aimed to evaluate the echogenicity of plaques and hemodynamic alteration by color duplex ultrasound (CDU) examination and investigate their effects on the residual stenosis after CAS.

METHODS

From June 2018 to June 2020, 454 patients (386 males and 68 females) with a mean age of 67.2 ± 7.9 years, who underwent CAS from 11 advanced stroke centers in China were enrolled. One week before recanalization, CDU was used to evaluate the responsible plaques, including the morphology (regular or irregular), echogenicity of the plaques (iso-, hypo-, or hyperechoic) and calcification characteristics (without calcification, superficial calcification, inner calcification, and basal calcification). One week after CAS, the alteration of diameter and hemodynamic parameters were evaluated by CDU, and the occurrence and degree of residual stenosis were determined. In addition, magnetic resonance imaging was performed before and during the 30-day postprocedural period to identify new ischemic cerebral lesions.

RESULTS

The rate of composite complications, including cerebral hemorrhage, symptomatic new ischemic cerebral lesions, and death after CAS, was 1.54% (7/454 cases). The rate of residual stenosis after CAS was 16.3% (74/454 cases). After CAS, both the diameter and peak systolic velocity (PSV) improved in the preprocedural 50% to 69% and 70% to 99% stenosis groups (P < .05). Compared with the groups without residual stenosis and with <50% residual stenosis, the PSV of all three segments of stent in the 50% to 69% residual stenosis group were the highest, and the difference in the midsegment of stent PSV was the largest (P < .05). Logistic regression analysis showed that preprocedural severe (70% to 99%) stenosis (odds ratio [OR], 9.421; P = .032), hyperechoic plaques (OR, 3.060; P = .006) and plaques with basal calcification (OR, 1.885; P = .049) were independent risk factors for residual stenosis after CAS.

CONCLUSIONS

Patients with hyperechoic and calcified plaques of the carotid stenosis are at a high risk of residual stenosis after CAS. CDU is an optimal, simple and noninvasive imaging method to evaluate plaque echogenicity and hemodynamic alterations during the perioperative period of CAS, which can help surgeons to select the optimal strategies and prevent the occurrence of residual stenosis.

History of Carotid Artery Reconstruction around the World and in Japan

Since ancient times, physicians have been aware of correlations between the carotid artery and consciousness; however, carotid stenosis was only recently identified as the cause of atherothrombotic ischemic stroke. In 1658, Wepfer described the first suggestion of a link between symptoms of cerebral arterial insufficiency and carotid pathology. In 1951, Fisher reported details of the symptoms and pathological findings and emphasized that cervical atheromatous lesions induced cerebral infarction with various symptoms. The beginning of carotid artery surgery was ligation of the carotid artery for neck or head injury, but surgeons were aware that this operation induced cerebral symptoms due to lack of blood supply. Carotid endarterectomy (CEA) was first reported by Eastcott et al. in 1954, and in Japan, Kimoto performed a successful CEA in 1962. In 1979, percutaneous transluminal angioplasty (PTA) was performed for patients with fibromuscular dysplasia, and then, carotid artery stenting (CAS) was first performed in 1989 by Mathias. In Japan, Kuwana et al. were the first to perform carotid PTA, in 1981, whereas Yamashita et al. performed the first CAS in 1997. Yoshimura et al. proposed staged carotid stenting to prevent hyperperfusion syndrome. Some issues in carotid reconstruction are still debated today, which include conventional (standard) CEA versus the eversion technique, CEA versus CAS versus medical therapy, and medical economic problems. In the future, we must continue to develop more effective, safer, and less expensive therapeutic methods to prevent carotid stroke, carrying on the efforts of the ancient peoples who pioneered this research.

Challenges and Pitfalls in CT-Angiography Evaluation of Carotid Bulb Stenosis: Is It Time for a Reappraisal?

We aimed to perform an anatomical evaluation of the carotid bulb using CT-angiography, implement a new reliable index for carotid stenosis quantification and to assess the accuracy of relationship between NASCET and ECST methods in a large adult population. The cross-sectional areas of the healthy carotid at five levels were measured by two experienced radiologists. A regression analysis was performed in order to quantify the relationship between the areas of the carotid bulb at different carotid bulbar level. A new index (Regression indeX, RegX) for carotid stenosis quantification was proposed. Five different stenoses with different grade in three bulbar locations were simulated for all patients for a total of 1365 stenoses and were used for a direct comparison of the RegX, NASCET, and ECST methods. The results of this study demonstrated that the RegX index provided a consistent and accurate measure of carotid stenosis through the application of the ECST method, avoiding the limitations of NASCET method. Furthermore, our results strongly depart from the consolidated relationships between NASCET and ECST values used in clinical practice and reported in extensive medical literature. In particular, we highlighted that a major misdiagnosis in patient selection for CEA could be introduced because of the large underestimation of real stenosis degree provided by the NASCET method. A reappraisal of carotid stenosis patients' work-up is evoked by the effectiveness of state-of-the-art noninvasive contemporary carotid imaging.

Protected carotid artery stenting in patients with severe stenosis

Intraplaque hemorrhage (IPH) and ulcers are the major findings of unstable plaques. In addition, initial symptoms are associated with postprocedural complications after carotid artery stenting (CAS). The aim of this study was to determine the safety of CAS using an embolic protection device in symptomatic patients with severe carotid artery stenosis and unstable plaques such as IPH and ulcers. This retrospective study included 140 consecutive patients with severe carotid stenosis. These patients underwent preprocedural carotid vessel wall imaging to evaluate the plaque status. We analyzed the incidence of initial clinical symptoms, such as headache, nausea, and vomiting, after CAS. The primary outcomes analyzed were the incidence of stroke, myocardial infarction, and death within 30 days of CAS. Sixty-seven patients (47.9%) had IPH, and 53 (38.9%) had ulcers on carotid wall imaging/angiography. Sixty-three patients (45.0%) had acute neurological symptoms with positive diffusion-weighted image findings. Intraluminal thrombi on initial angiography and flow arrest during CAS were significantly higher in patients with IPH and symptomatic patients. Symptoms were significantly higher in patients with IPH than in those without (63.5% vs 35.1%, P < .001). There were no significant differences in clinical symptoms after stenting or in primary outcomes, regardless of IPH, ulcer, or initial symptoms. IPH and plaque ulceration are risk factors in symptomatic carotid stenosis. However, IPH and plaque ulceration were not a significant risk factors for cerebral embolism during protected carotid artery stent placement in patients with carotid stenosis. Protected CAS might be feasible and safe despite the presence of unstable plaques.

Near Infrared Spectroscopy For Cerebral Hemodynamic Monitoring During Carotid Endarterectomy Under General Anesthesia

Background:

Near infrared spectroscopy (NIRS) is a noninvasive method for continuous monitoring of cerebral oxygenation.

Objective:

To describe the intraoperative behavior of NIRS variables used to evaluate hemodynamic response in patients with atherosclerotic disease undergoing carotid endarterectomy under general anesthesia.

Methods:

Fifteen volunteers with atherosclerotic carotid disease with indications for endarterectomy were evaluated. After selection of patients, carotid stenosis was confirmed by appropriate diagnostic methods. NIRS was used for intraoperative monitoring. The variables total hemoglobin (Hb), oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and regional oxygen saturation (rSO2) were evaluated at three intraoperative time points: before, during, and after carotid clamping.

Results and Discussion:

Measurements recorded by NIRS showed that, during the first 5 min of clamp time, patients experienced a decline in O2Hb levels, an increase in HHb levels, and a marked decrease in rSO2. Hb remained constant throughout the procedure. At the post-clamping time point, HHb, O2Hb, and rSO2 returned to patterns similar to those observed before clamping.

Conclusion:

NIRS was able to reliably and accurately identify the three stages of carotid endarterectomy and may predict the risk of cerebral hypoxia during carotid clamping under general anesthesia.

Carotid Artery Stenting Using the Snake Hunt Technique for Highly Tortuous Carotid Artery Stenosis: A Technical Note

In carotid artery stenting (CAS) for highly tortuous carotid stenosis, it is often difficult to guide rigid devices such as carotid stents. There are various adjunctive techniques using a guidewire: the buddy wire technique, the sheep technique, and the stiff guide technique. We report a case in which the tortuous vessel was straightened and a stent could be inserted. A 64-year-old man with amaurosis had highly tortuous left carotid stenosis. Despite the best medical treatments, he often had transient cerebral ischemic symptoms, so we planned CAS. We could insert the first stent, but the proximal vessel was kinked by the placement of the stent. It was so tortuous that the second stent could not be inserted by adjunctive techniques. Therefore, the proximal balloon was inflated and pulled back to straighten the tortuous vessel, and then we could insert the stent. We named this technique the "snake hunt technique" because it was just like catching a snake given that the tortuous vessel was stretched. This technique could be a troubleshooting step when it is difficult to insert a stiff device such as a stent or balloon even with the use of various adjunctive techniques.

Inadequate Adherence to Imaging Surveillance and Medical Management in Patients with Duplex Ultrasound-Detected Carotid Artery Stenosis

BACKGROUND

It is recommended that patients with ≥50% carotid artery stenosis undergo surveillance imaging and atherosclerotic risk reduction medical therapies, regardless of whether revascularization is performed. The objective of this study was to determine rates of adherence to these recommended measures and to identify risk factors for nonadherence.

METHODS

A retrospective analysis was performed of all carotid duplex ultrasound (DUS) from 2016 to 2017 at a single institution. Patients with unilateral or bilateral ≥50% carotid stenosis were included. Primary outcomes were rates and timing of surveillance imaging and medication regimen. Patient and study characteristics were compared using univariate and multivariable analyses. A subgroup analysis of patients with a new finding of carotid stenosis was also performed.

RESULTS

Carotid stenosis >50% was detected in 340 patients. Overall, 182 patients (54%) had follow-up imaging (median 261 days [IQR 166-366]) and 158 patients (46%) had no imaging follow-up (NIFU). NIFU patients had similar rates of aspirin use (86% vs. 88%, P = 0.6) and tobacco cessation counseling (71% vs. 71%, P = 0.8) but had less statin use (85% vs. 94%, P = 0.01) compared to those with imaging follow-up. Subsequent carotid revascularization was more common in patients with imaging follow-up (18% vs. 3%, P < 0.001). NIFU patients were less likely to have Medicare or commercial insurance (54% vs. 75%, P < 0.001). The indication for DUS in NIFU patients, compared to those in follow up, was less commonly neurologic symptoms (11% vs. 14%), more commonly other clinical findings (35% vs. 16%), and more commonly as work up before nonvascular surgery (25% vs. 4%, P < 0.001), respectively. NIFU rates decreased with increasing degree of carotid stenosis. Prior carotid intervention, prior DUS, or DUS ordered by a vascular surgeon were characteristics associated with imaging follow-up (P < 0.05 for all). In a subgroup of 160 patients with new carotid stenosis, a majority (64%) had NIFU and statin use was lower in these patients (82% vs. 96%, P = 0.007). On multivariable analysis, preop indication was predictive of NIFU (odds ratio [OR] 8.1 [95% confidence interval, CI 2.5-26.4], P < 0.001) whereas protective factors included: 70-80% stenosis (OR 0.33 [95% CI 0.14-0.76], P = 0.01), study ordered by vascular surgeon (OR 0.40 [95% CI 0.19-0.83], P = 0.01), and Medicare/commercial insurance (OR 0.36 [95% CI 0.2-0.66], P = 0.001).

CONCLUSIONS

Nearly half of patients found to have ≥50% carotid stenosis on DUS had no imaging follow-up; these patients were less likely to be on recommended statin therapy. The benefits of nonrevascularization-based treatments for carotid disease require adherence to therapy. Forgoing surveillance imaging in patients with hemodynamically significant carotid stenosis should be a shared decision between provider and patient and does not obviate the need for medical therapies.

Surgical Approaches to Stroke Risk Reduction

PURPOSE OF REVIEW

Surgical vascular intervention is an important tool in reducing the risk of stroke. This article examines the evidence for using the available options.

RECENT FINDINGS

Carotid endarterectomy is an effective treatment option for reducing the risk of stroke in appropriately selected patients. Patients should be stratified for future stroke risk based on both the degree of stenosis and the presence of symptoms referable to the culprit lesion. Carotid stenting is also useful in reducing stroke risk, again in carefully selected patients. Because of the publication of significant data regarding both carotid endarterectomy and carotid artery stenting in the last several years, selection can be far more personalized and refined for individual patients based on demographics, sex, patient preference, and medical comorbidities. Routine extracranial-intracranial bypass surgery remains unproven as a therapeutic option for large vessel occlusion in reducing the incidence of ischemic stroke although some carefully screened patient populations remaining at high risk may benefit; procedural risks and pathology related to alterations in blood flow dynamics are challenges to overcome. Indirect revascularization remains an appropriate solution for carefully selected patients with cerebral large vessel steno-occlusive disease, and multiple variations of surgical technique are patient specific. Indirect revascularization may benefit from clinical trials with larger patient populations for validation in specific pathologies and offers the advantages of lower surgical complication rates and reduced risk of pathologic responses to altered cerebral flow dynamics.

SUMMARY

Surgical solutions to reduce stroke risk provide important alternatives in appropriately selected patients and should be considered in addition to medical management and lifestyle modification for optimizing patient outcomes.

[A 20-year experience in surgical treatment of steno-occlusive lesion of craniocervical arteries at the Burdenko Neurosurgical Center]

INTRODUCTION

Surgical treatment of cerebral ischemia at the Burdenko Neurosurgical Center for the period from 1999 to 2019 is analyzed in the paper. The details of the treatment strategy in patients with steno-occlusive lesion of craniocervical arteries followed by cerebral ischemia developed over 20 years are discussed in the article. We have analyzed the features of surgical interventions on the major craniocervical arteries in a neurosurgical clinic and the results of this treatment.

OBJECTIVE

To demonstrate management of various lesions of major cerebral arteries in modern neurosurgical vascular hospital.

MATERIAL AND METHODS

In total, there were 3098 interventions on the major cerebral arteries in 2527 patients for this period. Mean age of patients ranged from 1.5 to 91 years (58±14 years). Interventions included open reconstructions of the carotid arteries (2031 surgeries), reconstructions of the vertebrobasilar arteries (135 surgeries), brain revascularization (658 surgeries), excision of the tumors of neurovascular bundle on the neck compressing carotid arteries (51 interventions). Endovascular interventions were performed in 223 cases and consisted of angioplasty and stenting of the extracranial segments of craniocervical arteries (185 surgeries), stenting of the intracranial arteries (30 surgeries) and endovascular thrombextraction (8 cases). Staged surgeries were performed in 541 patients (22.3%).

RESULTS

Favorable outcomes were obtained in 87.6% of cases, satisfactory results - in 9% of patients. Clinical deterioration due to long-term postoperative complications and recurrent strokes occurred in 2.9% of cases. Postoperative morbidity rate was 4.6%, persistent neurological deficit developed in 2.6% of cases. Mortality rate was 0.5%.

CONCLUSION

Surgical treatment of stenotic and occlusive lesion of the major cerebral arteries is an interdisciplinary problem. Solution of this issue is closely associated with technological progress, new discoveries in normal and pathological physiology, as well as clinical researches. Individualized choice of surgical approach is one the main modern trends of neurosurgical approach to this problem. At the same time, own surgical experience is the most important factor determining the results of arterial reconstructions.

A critical appraisal of bypass surgery in moyamoya disease

Moyamoya disease (MMD) is a complex cerebrovascular disorder about which little is known. Conventionally, revascularization surgery is recommended for patients, despite an absence of conclusive data from adequate clinical trials. Underscoring the uncertainty that exists in treating MMD patients, investigators continue to present data comparing revascularization with conservative or medical management, most of which originates from East Asia where MMD is most prevalent. The purpose of this manuscript is to review contemporary large case series, randomized trials, and recent meta-analyses that compare surgical and medical treatments in adult patients with MMD, and to critically analyze the modern literature in the context of current practice standards. Data from the available literature is limited, but revascularization seems superior to conservative therapy in adult patients presenting with hemorrhage, and in preventing future hemorrhages. Conversely, evidence that surgery is superior to medical therapy is not convincing in adult patients presenting with cerebral ischemia, or for the prevention of future ischemic events. In contrast to East Asian populations, MMD in Europe and in the Americas is predominantly an ischemic disease that presents in adulthood. Adequate multinational trials are warranted.