Historical perspective of carotid artery stenting in Japan: analysis of 8,092 cases in The Japanese CAS survey

Treatment Results of Carotid Artery Stenting with an Open-Cell Stent: Analysis of 734 Consecutive Cases at a Single Center

OBJECTIVE

In carotid artery stenting (CAS) for internal carotid artery stenosis, the stent is often selected according to the plaque properties and arterial tortuosity. In our institute, an open-cell stent is used as the first-line stent regardless of the characteristics of the lesion. This study was performed to examine the outcome of CAS with an open-cell stent as the real-world results.

METHODS

In total, 811 CAS procedures using open-cell stents were performed for internal carotid artery stenosis from April 2002 to December 2019. Of these patients, we excluded those with hyperacute conditions for which CAS was performed within 3 days of onset, those in whom acute mechanical thrombectomy was performed simultaneously with CAS, and those with stenosis due to arterial dissection. Thus, 734 patients were retrospectively analyzed. Perioperative and long-term outcomes and risk factors for perioperative infarction were investigated.

RESULTS

The periprocedural stroke rate and mortality rate were 3.7% (27/734) and 0.4% (3/734), respectively. Low-echoic plaque was a significant risk factor for periprocedural stroke in both univariate (P < 0.03) and multivariate (odds ratio, 2.69; 95% confidence interval, 1.14-6.66; P = 0.02) analyses. Cerebral infarction and high grade restenosis were observed in 15 (2.0%) and 17 (2.3%) patients during a median 50-month follow-up.

CONCLUSIONS

CAS with open-cell stents showed good results in terms of both the postoperative stroke incidence and long-term severe restenosis rate. However, low-echoic plaque was a risk factor for perioperative stroke incidence, which should be considered when deciding on the indication for CAS with an open-cell stent.

Comparison of the Clinical Outcome of Carotid Artery Stenting Between Institutions With a Treatment Strategy Based on Risk Factors and Those With First-Line Treatment

PURPOSE

Carotid endarterectomy (CEA) and carotid artery stenting (CAS) are recommended based on certain risk factors. The volume of an institution's treatment experience may be associated with good clinical outcomes. There is a dilemma between the treatment strategy based on risk factors and the experience volume. Therefore, we investigated the clinical outcomes of CAS performed at institutions that selected the treatment strategy based on risk factors and those that performed CAS at the first-line treatment.

MATERIALS AND METHODS

Patients who underwent CAS at 5 institutions were included in this retrospective case-control study. We defined CEA/CAS institutions as those that selected the treatment option based on risk factors, and CAS-first institutions as those that performed CAS as the first-line treatment. We investigated cases of ischemic stroke, hemorrhagic stroke, myocardial infarction, and deaths within 30 days of the intervention between the CEA/CAS- and CAS-first institution groups. One-to-one propensity score matching was performed to compare rates of ischemic and hemorrhagic strokes within 30 days of the intervention.

RESULTS

A total of 239 and 302 patients underwent CAS at the CEA/CAS institutions and CAS-first institutions, respectively; ischemic stroke occurred in 12 (5.0%) and 7 patients (2.3%), respectively (p=0.09). No differences in major ischemic strokes (0.8% vs 1.3%; p=0.59), hemorrhagic strokes (0.4% vs 0.3%; p=0.87), or deaths (0.0% vs 0.7%; p=0.21) were observed. Myocardial infarction did not occur in either group. Propensity score analysis showed that ischemic stroke (odds ratio: 1.845, 95% confidence interval: 0.601-5.668, p=0.28) and hemorrhagic stroke (odds ratio: 1.000, 95% confidence interval: 0.0061-16.418, p=1.00) were not significantly associated with either institution group.

CONCLUSIONS

The CAS-specific treatment strategies for CAS can achieve the same level of outcomes as the treatment strategy based on risk factors. The CAS performed based on risk factors in CEA/CAS institutions and the treatment of more than 30 patients/year/institution in CAS-first institutions were associated with good clinical outcomes.

Clinical Outcomes of Second- versus First-Generation Carotid Stents: A Systematic Review and Meta-Analysis

Background: Single-cohort studies suggest that second-generation stents (SGS; “mesh stents”) may improve carotid artery stenting (CAS) outcomes by limiting peri- and postprocedural cerebral embolism. SGS differ in the stent frame construction, mesh material, and design, as well as in mesh-to-frame position (inside/outside). Objectives: To compare clinical outcomes of SGS in relation to first-generation stents (FGSs; single-layer) in CAS. Methods: We performed a systematic review and meta-analysis of clinical studies with FGSs and SGS (PRISMA methodology, 3302 records). Endpoints were 30-day death, stroke, myocardial infarction (DSM), and 12-month ipsilateral stroke (IS) and restenosis (ISR). A random-effect model was applied. Results: Data of 68,422 patients from 112 eligible studies (68.2% men, 44.9% symptomatic) were meta-analyzed. Thirty-day DSM was 1.30% vs. 4.11% (p < 0.01, data for SGS vs. FGS). Among SGS, both Casper/Roadsaver and CGuard reduced 30-day DSM (by 2.78 and 3.03 absolute percent, p = 0.02 and p < 0.001), whereas the Gore stent was neutral. SGSs significantly improved outcomes compared with closed-cell FGS (30-day stroke 0.6% vs. 2.32%, p = 0.014; DSM 1.3% vs. 3.15%, p < 0.01). At 12 months, in relation to FGS, Casper/Roadsaver reduced IS (−3.25%, p < 0.05) but increased ISR (+3.19%, p = 0.04), CGuard showed a reduction in both IS and ISR (−3.13%, −3.63%; p = 0.01, p < 0.01), whereas the Gore stent was neutral. Conclusions: Pooled SGS use was associated with improved short- and long-term clinical results of CAS. Individual SGS types, however, differed significantly in their outcomes, indicating a lack of a “mesh stent” class effect. Findings from this meta-analysis may provide clinically relevant information in anticipation of large-scale randomized trials.

Carotid Angioplasty and Stenting for Occlusive Diseases

Stenting for carotid artery stenosis (CAS) was once denied 15 years ago because it failed to prove the non-inferiority to carotid endarterectomy (CEA). However, it is now reevaluated and is thought better due to higher safety and efficacy thanks to the development of devices, strategies, and various protection methods. To achieve the safe CAS, protection methods and stents should be properly selected based on the vessel course and plaque components on the preoperative plaque images. Particularly multiple protection methods including proximal balloon protection and double-layer micromesh stents are useful for the cases with high-risk and fragile plaque. Perioperative anti-platelet management and the control of blood pressure are also important to avoid the ischemic complications and hyperperfusion. Properly protected and tailored CAS based on the risk management has dramatically improved the clinical results and contributed to extend the indication for more difficult lesions.

Clinical trial of carotid artery stenting using dual-layer CASPER stent for carotid endarterectomy in patients at high and normal risk in the Japanese population

BACKGROUND

The dual-layer nitinol CASPER stent was designed to prevent plaque prolapse into its strut and periprocedural stroke.

OBJECTIVE

To conduct a clinical trial for government approval of the device in patients at either high or normal risk for carotid endarterectomy (CEA).

METHODS

Eligible patients had ≥50% symptomatic stenosis or ≥80% asymptomatic stenosis according to the North American Symptomatic Carotid Endarterectomy Trial methods (peak systolic velocity 130 and 230 cm/s on ultrasonography, respectively). The primary endpoint was the lack of major adverse events (MAEs), defined as death, stroke, and myocardial infarction within 30 days, and ipsilateral stroke within 1 year. The performance goal was set at 90.5%. MAE rates were also compared between the CEA high- and normal-risk groups.

RESULTS

140 carotid artery stenting procedures, including 40% of patients at high risk and 60% at normal risk for CEA, were performed in 13 institutes. MAEs occurred in two cases (one intraprocedural and one postprocedural stroke), and the MAE rate was 1.4%. The non-MAE rate was 98.6% according to Kaplan-Meier analysis, which was superior to the previously set performance goal. The deployment success, target lesion revascularization (TLR), in-stent restenosis, and cerebrovascular event rates were 99.3%, 2.4%, 8.5%, and 7.2%, respectively. The MAE rate in patients with normal CEA risk was 1.2%, which was similar to the high-risk CEA group, with no significant difference due to the small number of MAEs.

CONCLUSIONS

The MAE rate following use of the CASPER stent was low (1.4%). The MAE, deployment success, TLR, in-stenosis, and cerebrovascular event rates were similar to those of previous reports.

Long-term Outcomes of Carotid Artery Stenting: A Single-center Experience

The long-term prophylactic effect of carotid artery stenting (CAS) remains incompletely elucidated. We evaluated outcomes of CAS at our institution to determine the safety and efficacy of CAS in real-world settings. We retrospectively analyzed 73 patients who underwent CAS from 2006 to 2013. Periprocedural results were compared between asymptomatic and symptomatic carotid stenosis groups. The primary endpoint was a composite of ipsilateral stroke, death, and carotid artery restenosis beyond 30 days and within 5 years after the first procedure. The average age was 72.2 years with a majority of male subjects (84.9%). Twenty-seven patients (37%) were asymptomatic. Incidence of periprocedural adverse events and mRS ≤2 at 30 days after CAS were not significantly different between groups (P = 0.14 and 0.07, respectively). CAS was unsuccessful in three patients and one post-procedural minor stroke occurred. Therefore, 69 patients were included in the long-term study. The rate of occurrence of the primary endpoint was 21.7%. Ipsilateral ischemic stroke occurred in one patient, which was due to cardiogenic embolus. Nine patients died, and cancer was the most frequent cause. Five in-stent restenoses were observed. All patients with restenosis underwent additional CAS without any occurrence of stroke. This study revealed the safety and long-term efficacy of CAS in a real-world setting. Routine follow-up is also important for detecting carotid artery restenosis.

Safety of carotid artery stenting for elderly patients with cervical carotid artery stenosis

BACKGROUND

Several recent randomized controlled trials have reported that perioperative complications of carotid artery stenting increase with age, and Japan has the highest proportion of elderly in the world. We retrospectively compared clinical factors, treatment outcomes, and adverse events between younger and elderly carotid artery stenting patients at a single institution in Japan to assess carotid artery stenting safety for the aged population.

METHODS

A total of 150 consecutive patients treated with carotid artery stenting using the dual protection (simultaneous flow reversal and distal filter) and blood aspiration method were enrolled. Patients were classified into an elderly (O) group ≥75 years (54/150, 36.0%) and a younger (Y) group <75 years (96/150, 64%) for comparison of demographics, clinical background, incidence of captured debris during the procedure, outcome, minor stroke, major adverse events (major stroke, myocardial infarction, or death) within 30 days, hyperintense spots on diffusion-weighted images after carotid artery stenting, and postoperative hospitalization days.

RESULTS

The carotid artery stenting procedure was successful in all cases. No major adverse events occurred within 30 days in the Y group, and only one occurred in the O group (P = 0.348). Visible debris was captured in a significantly greater proportion of O group patients than in Y group patients (33/54 (63.5%) vs. 40/96 (42.1%), P = 0.016), but there was no significant difference in the frequency of hyperintense spots on diffusion-weighted images between Y and O groups (23/96 (24.0%) vs. 16/52 (30.8%), P = 0.435).

CONCLUSIONS

Carotid artery stenting using dual protection and blood aspiration is equally safe for younger and elderly patients.

Safety and efficacy of an open-cell stent and double-balloon protection for unstable plaques: analysis of 184 consecutive carotid artery stentings

INTRODUCTION

In our institute, most cases of carotid artery stenosis are treated by carotid artery stenting (CAS) with an open-cell stent and double-balloon protection, even if plaques are unstable. This study was performed to examine the outcome of CAS with an open-cell stent and double-balloon protection for unstable plaques.

METHODS

A total of 184 CAS procedures in our institute between October 2010 and February 2018 were assessed. Ultrasonography findings of low-echo plaques, plaque ulceration, or both were defined as unstable plaques. A plaque-to-muscle ratio (PMR) of >1.8 on T1-weighted black blood imaging using spin-echo was also defined as an unstable plaque. Seventy-four unstable plaques on ultrasonography and 86 unstable plaques evaluated by PMR were included. Open-cell stents and double-balloon protection (proximal balloon protection during lesion crossing and distal balloon protection after lesion crossing) were used in all cases.

RESULTS

On ultrasonography, perioperative asymptomatic thromboembolization was significantly more frequent in the unstable plaque group (39/74, 52.7%) than in the stable plaque group (41/110, 37.3%, p=0.0384). Asymptomatic thromboembolization was also significantly more frequent in the PMR >1.8 group (44/86, 51.2%) than in the PMR <1.8 group (36/98, 36.7%, p=0.0489). However, symptomatic thromboembolization was rare (n=5, 2.7%), and all of these patients had minor stroke. During the 4-year follow-up, the risk of ipsilateral stroke was 0.28% and 0.27% per year in patients with symptomatic and asymptomatic lesions, respectively.

CONCLUSIONS

The outcomes of CAS with an open-cell stent and double-balloon protection are acceptable. This method is effective and safe, even if carotid artery stenosis comprises unstable plaques.

Tailored Strategies in Carotid Artery Stenting to Avoid Periprocedural Complications

Carotid artery stenting (CAS) has been widely accepted as a valuable therapeutic alternative to carotid endarterectomy (CEA) for high-grade carotid stenosis. Because carotid revascularization including CAS is usually performed in patients with minimal or no neurological deficits, utmost care should be taken to avoid periprocedural complications. The major concerns associated with CAS are embolic stroke, hyperperfusion syndrome (HPS), and perioperative myocardial infarction.Plaque characteristics, cerebral blood flow (CBF) in the affected cerebral hemisphere, and concomitant coronary artery disease prior to CAS are all important to assess the risks of these complications and are routinely evaluated.Tailored CAS is planned based on findings of preoperative evaluation, as follows. (1) If the plaque component is thought vulnerable, proximal embolic protection methods, use of a closed-cell-type stent, or referral to CEA should be considered to avoid embolic complications. (2) If patients have severe CBF impairment, staged angioplasty is an effective strategy to prevent postoperative HPS. (3) If concomitant cardiac diseases are present, the optimal treatment sequence should be discussed between cardiologists and neurointerventionalists.These tailored strategies based on preoperative risk evaluations may lead to safer procedures and better clinical outcome in CAS patients.

Objective evaluation of cerebrovascular reactivity for acetazolamide predicts cerebral hyperperfusion after carotid artery stenting: Comparison with region of interest methods

BACKGROUND AND PURPOSE

Hemodynamic impairments are considered risk factors of cerebral hyperperfusion after carotid artery stenting (CAS); measurement by Single-photon emission computed tomography (SPECT) using a subjective region of interest (ROI) method lacks consistency and reproducibility.

MATERIALS AND METHODS

The present study compared objective perfusion analysis (stereotactic extraction estimation [SEE] method) with the ROI method for preoperative SPECT to predict the hyperperfusion phenomenon (HPP) after CAS. Preoperative resting asymmetry index (cerebral blood flow [CBF] ratio from the affected to unaffected hemisphere) and cerebrovascular reactivity (CVR) to acetazolamide were measured by N-isopropyl-p-[¹²³I]-iodoamphetamine SPECT using the SEE and ROI method in 84 patients. CBF was also measured the day after CAS. Perfusion data with the highest area under the curve (AUC) by receiver-operating characteristic (ROC) analysis was considered a perfusion risk factor of HPP. Multivariate analyses for clinical characteristics and perfusion risk factors were performed to determine predictors of HPP.

RESULTS

The HPP was observed in 10 patients (11.9%). Female sex, contralateral stenosis, and degree of stenosis were significantly associated with HPP development on univariate analysis, and symptomatic stenosis was not found to be a significant factor. On SPECT analysis, CVR in the MCA area by SEE method had the highest AUC (0.981). Multivariate analysis showed that CVR in the MCA area was a significant predictor of HPP (P=0.041). To predict hyperperfusion, the ROC curve of the CVR showed a cutoff value of -0.60%, sensitivity of 94.6%, and specificity of 100% (P<0.001).

CONCLUSIONS

Objective SEE method had better a predictive capability than ROI method to identify risk of hyperperfusion after CAS.

Follow-up after undersized dilatation of targeted lesions in carotid artery stenting

BACKGROUND AND PURPOSE

We assessed whether intentional undersized dilatation of targeted lesions during carotid artery stenting (CAS) carried a higher risk of in-stent restenosis (ISR) and correlation to subsequent ischemic stroke in qualifying arteries in the follow-up period.

METHODS

Consecutive patients undergoing CAS between April 2003 and May 2010 were retrospectively reviewed. The use of a filter device as a distal embolic protection device (EPD) was first approved by Japanese governmental health insurance in April 2008; previously, transient balloon occlusion was used off-label. Until March 2008 (Group A), the target diameter of balloon dilatation was 80-100% of the normal vessel diameter just distal to the stenotic lesion. Moderately undersized dilatation (70-80% of the normal vessel diameter) using the distal EPD was adopted in April 2008 (Group B) in an attempt to reduce the amount of released plaque debris.

RESULTS

We analyzed 132 CAS procedures (125 patients) in Group A and 53 CAS procedures (52 patients) in Group B. The mean follow-up period was 35.4 months (35.3 months in Group A and 36.0 months in Group B). Eight lesions (4.3%; 7 in Group A and 1 in Group B) developed ISR. None of the patients had symptomatic ISR, and ISR did not increase in Group B (odds ratio, 0.34; 95% confidence interval, 0.04-2.86; p = 0.32).

CONCLUSIONS

Undersized dilatation of targeted lesions did not increase the risk of developing ISR, and we suggest it as a viable treatment option to prevent ischemic events during CAS.

Selecting an appropriate surgical treatment instead of carotid artery stenting alone according to the patient's risk factors contributes to reduced perioperative complications in patients with internal carotid stenosis: a single institutional retrospective analysis

This retrospective study was aimed to compare the perioperative complications for internal carotid artery stenosis (ICS) in a Japanese single institute between the use of carotid artery stenting (CAS) alone or the use of an appropriate individualized treatment method allowing either carotid endarterectomy (CEA) or CAS based on patient risk factors. Based on the policy at our hospital, only CAS was performed on patients (n = 33) between January 2005 and November 2009. From December 2009 to December 2012, either CEA or CAS (tailored treatment) was selected for patients (n = 61) based on individual patient risk factors. CEA was considered the first-line treatment in all cases. In high-risk CEA cases, CAS was performed instead (n = 11), whereas in low-risk CEA cases, CEA was performed (n = 19). Further, in moderate-risk CEA cases based on own criteria, CAS was considered first, whereas for high-risk CAS cases, CEA was performed (n = 17). For low-risk CAS cases, CAS was performed (n = 9). Perioperative clinical complications (any stroke, myocardial infarction, or death within 30 days) were compared between both periods. Significantly reduced perioperative complications were observed during the tailored period (4/61 sites, 6.6%) as compared with the CAS period (8/33 sites, 24.2%) [Fisher’s exact test p = 0.022; odds ratio, 4.56 (CAS/tailored); 95% confidence interval, 1.26–16.5]. Selecting an appropriate individualized treatment method according to patient risk factors, as opposed to adhering to a single treatment approach such as CAS, may contribute to improved overall outcomes in patients with ICS.

Real-world experience of carotid artery stenting in Japan: analysis of 7,134 cases from JR-NET1 and 2 nationwide retrospective multi-center registries

The present study aimed to demonstrate the “real-world” experiences of carotid artery stenting (CAS) in Japan using Japanese Registry of Neuroendovascular Therapy (JR-NET) 1 and 2, retrospective nationwide multi-center surveillances. JR-NET1 and 2 registries are retrospective surveillances conducted between January 2005 and December 2007 and January 2008 and December 2009, respectively, in Japan regarding neuroendovascular therapy. A total of 7,134 procedures (1,943 for JR-NET1 and 5,191 for JR-NET2) were included in this study and retrieved data were analyzed retrospectively. Treatment results of two surveillance periods were similar. In JR-NET2 registry, total of 5,191 lesions were treated by CAS and 5,008 of 5,191 procedures (96.5%) were performed by the board-certified surgeons of Japanese Society of Neuroendovascular Therapy. The rate of technical success was extremely high (99.99%), and the rate of clinically significant complication was low (3.2%). These results were comparable to a previous large study in Japan. Multivariate logistic analysis revealed that age [odds ratio (OR), 1.04 per year; 95% confidence interval (CI), 1.02–1.07; p = 0.0004), symptomatic lesion (OR, 1.87; 95% CI; p = 0.0004), and the use of closed-cell type stent (OR, 0.58; 95% CT, 0.32–1.00; p = 0.05) were independently associated with clinically significant complications. It was revealed that good clinical results were achieved in patients who underwent CAS in Japan. It is expected that the evolution of devices and increasing experiences of surgeons would lead to further improvement of the clinical results, and further investigation would be required to clarify the optimal treatment strategy and therapeutic efficacy of CAS, especially in symptomatic lesions.

[How do the interventional neurologists function in the clinical setting?]

Neuroendovascular therapy is a rapidly evolving clinical subspecialty because of its minimal invasiveness and novel device development. In Japan, neurosurgeons perform a substantial portion of neuroendovascular procedures, however, the number of neurologists who certified by the Japanese Society for Neuroendovascular Therapy (interventional neurologist) is gradually increasing. Neurologists tend to deal with medical treatment in the acute stage and prevention of ischemic stroke, in addition, neuroendovascular procedures for ischemic cerebrovascular diseases performed by neurologists themselves, such as acute revascularization therapy for acute intracranial major artery occlusion or carotid artery stenting, might provide various benefits to ischemic stroke patients because of the smooth, seamless and close management from admission, to intervention, to discharge and after discharge. Because of insufficient number of interventionists to perform emergent neurointerventional procedures in the clinical setting of acute ischemic stroke in Japan, we wish that more neurologists get interested in and receive training in the neuroendovascular therapy.

Endovascular intervention for acute cervical carotid artery occlusion

BACKGROUND

Acute cervical carotid artery occlusion presents with a severe neurological deficit and is associated with unfavorable outcomes. In this study, the authors report their experience with patients having had acute ischemic stroke due to cervical carotid occlusion, who underwent endovascular intervention.

METHOD

Sixteen acute cervical carotid occlusion patients (15 males and 1 female; mean age 67.7 years) were treated by endovascularly between January 2009 and November 2012. Clinical, procedural, and angiographic data were retrospectively evaluated. Successful intracranial recanalization was based on thrombolysis in cerebral infarction score of 2B-3. A favorable outcome was defined as a modified Rankin Scale score of 0-2 at 90 days.

FINDINGS

The average score of National Institutes of Health Stroke Scale before treatment was 15.9. Ten of 16 patients (63 %) were associated with intracranial tandem occlusion. Ten (63 %) cases were caused by atherosclerotic, 4 (25 %) by atrial fibrillation (AF), and 2 (13 %) by dissection. Thirteen of 16 (81 %) achieved successful cervical recanalization and 7 of 16 (44 %) patients obtained sufficient cervical and intracranial perfusion. As a result, 5 of 16 (31 %) patients demonstrated favorable outcomes. Five of seven patients (71 %) with successful cervical and intracranial recanalization presented favorable outcomes. In contrast, none of the patients without cervical or intracranial recanalization presented favorable outcomes. Three of 6 (50 %) patients initially without intracranial occlusion showed favorable outcomes, but only 2 of 10 (20 %) patients associated with intracranial occlusion had favorable outcomes. On the aspect of etiology, in atherosclerotic cases, 4 of 10 (40 %) showed favorable outcomes. However, all four AF cases deteriorated into poor outcomes.

CONCLUSIONS

This study demonstrated the feasibility of endovascular intervention for acute cervical carotid artery occlusion. Although treatment for tandem occlusion and AF cases is an issue that should be resolved, intervention must be encouraged. Successful cervical and intracranial revascularization will be essential for favorable outcomes.