Initial Clinical Results and In Vitro Testing of the New CGuard MicroNet-Covered "One-Size-Fits-All" Carotid Stent

Carotid Artery Stenting With Double-Layer Stent: A Systematic Review and Meta-Analysis

BACKGROUND

Carotid artery stenting (CAS) in the treatment of significant stenosis is a cause of stroke due to both plaque prolapse and cerebral embolization. New types of stents with a double-layer structure have been designed to minimize plaque prolapse and embolization; these double-layer stents (DLSs) should be able to reduce the stroke risk; however, definite data on their performance are scarce in the literature.

METHODS

A systematic search was performed through PubMed, Scopus, and Cochrane Library, according to PRISMA guidelines; all studies on CAS with DLS (Roadsaver/Casper or CGuard) up to January 1, 2022, with a cohort of at least 20 patients were considered eligible. The present meta-analysis was approved and registered on PROSPERO register (CRD42022297512). Patients with tandem lesions or complete carotid occlusion were excluded from the study. The 30-day stroke rate after CAS was analyzed evaluating the preoperative symptomatic status and DLS occlusion. The estimated pooled rate of events was calculated by random effect model and moderators were evaluated.

RESULTS

A total of 14 studies were included in the meta-analysis for a total of 1955 patients. The estimated overall (95% confidence interval [CI]) stroke rate was 1.4% (0.9%-2.2%, I2 = 0%), which was not influenced by the type of DLS used: CGuard 0.8% (0.4%-1.8%, I2 = 0%) versus Roadsaver/Casper 1.5% (0.7%-3.2%, I2 = 0%), p=0.30. The 30-day estimated stroke rate was 1.5% (0.8%-2.9%, I2 = 0%) in asymptomatic and 1.9% (1.0%-3.6%, I2 = 0%) in symptomatic patients, with no influence by moderators. The 30-day DLS occlusion rate was 0.8% (0.4%-1.8%, I2 = 0%). The publication bias assessment identified asymmetry in the asymptomatic populations.

CONCLUSION

The overall 30-day stroke rate in CAS with DLS is low (1.4%), with similar results in symptomatic and asymptomatic patients. Acute occlusion of DLS is rare (0.8%). Further studies are necessary to reduce the publication bias for asymptomatic patients.

CLINICAL IMPACT

CAS with DLS is associated to a low rate of 30-day stroke in both symptomatic (1.9%) and asymptomatic (1.5%) patients. The type of DLS (CGuard or Roadsaver/Casper) did not affect the 30-day stroke rate.

CIRSE Standards of Practice on Carotid Artery Stenting

BACKGROUND

Carotid artery stenting has been used effectively to treat internal carotid artery stenosis since 1989 (Mathias et al. in World J Surg. 25(3):328-34, 2001), with refined and expanded techniques and tools presently delivering outstanding results in percutaneous endoluminal treatment of carotid artery stenosis.

PURPOSE

This CIRSE Standards of Practice document is directed at interventional radiologists and details the guidelines for carotid artery stenting, as well as the different implementation techniques. In addition to updating all previously published material on the different clinical indications, it will provide all technical details reflective of European practice for carotid artery stenting. CIRSE Standards of Practice documents do not aim to implement a standard of clinical patient care, but rather to provide a realistic strategy and best practices for the execution of this procedure.

METHODS

The writing group, which was established by the CIRSE Standards of Practice Committee, consisted of five clinicians with internationally recognised expertise in carotid artery stenting procedures. The writing group reviewed existing literature on carotid artery stenting procedures, performing a pragmatic evidence search using PubMed to select relevant publications in the English language from 2006 to 2022.

RESULTS

Carotid artery stenting has an established role in the management of internal carotid artery stenosis; this Standards of Practice document provides up-to-date recommendations for its safe performance.

Development of an in vitro setup for flow studies in a stented carotid artery bifurcation

To investigate flow conditions in a double-layered carotid artery stent, a bench-top in vitro flow setup including a bifurcation phantom was designed and fabricated. The geometry of the tissue-mimicking phantom was based on healthy individuals. Two identical phantoms were created using 3D-printing techniques and molding with PVA-gel. In one of them, a clinically available CGuard double-layer stent was inserted. Measurements were performed using both continuous and pulsatile flow conditions. Blood flow studies were performed using echoPIV: a novel ultrasound-based technique combined with particle image velocimetry. A maximum deviation of 3% was visible between desired and measured flow patterns. The echoPIV measurements showed promising results on visualization and quantification of blood flow in and downstream the stent. Further research could demonstrate the effects of a double-layered stent on blood flow patterns in a carotid bifurcation in detail.

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).

Vascular surgery study of the CGuard MicroNet-covered stent in patients with indication to carotid revascularization: POLGUARD

BACKGROUND

In a recent randomized study, MicroNet-covered stent (CGuard) significantly reduced procedural and post-procedural cerebral embolism in relation to a single-layer CREST study carotid stent, but real-life clinical practice data are limited. The aim is to prospectively assess clinical outcomes of CGuard as a routine revascularization tool for patients with indication to carotid revascularization.

METHODS

From April 2019 to November 2021, 204 elective patients (age 71.0±7.1years, 69.6% males, 21.7% symptomatic) were enrolled.

RESULTS

Mean basal peak-systolic velocity was 251.41±91.85 cm/s with angiographic diameter stenosis 89.7±8.46%. About 34.4% lesions were severely calcified, 6.8% were angulated, and 4.4% showed significant access tortuosity. Access was femoral, with 100% protection device (filter) use. Two hundred and three lesions in 203 patients were treated (1 cross-over to surgery for lack of effective access, no cross-over to other devices); in most cases (66.9%) the stent was placed directly. For pre-dilated lesions, mean balloon diameter was 3.36±0.34mm. Mean nominal stent diameter was 7.64±0.5 mm; length was 37.19±4.5 mm. All stents were post-dilated (balloon diameter 5.2±0.25 mm). Residual stenosis was <30% in all (3.77±6.91%). By discharge, there were 2 minor strokes (0.9%) and one transient ischemic attack. By 30-days, one other minor stroke occurred in relation to de-novo atrial fibrillation. With no deaths or myocardial infarctions, 30-day total death/stroke/myocardial infarction rate was 1.48%. No in-stent thrombosis or patency loss occurred by 30-days. In-stent peak-systolic velocity was 55.49±22.73 cm/s.

CONCLUSIONS

Thirty-day results from POLGUARD study indicate safety and a low complication rate of the MicroNet-covered carotid stent use in every-day vascular surgery practice of carotid revascularization. Long-term observation is underway.

Revisiting SFA stent technology: an updated overview on mechanical stent performance

OBJECTIVES

The study investigated mechanical parameters of stent systems indicated for treatment of femoropopliteal (FP) arterial disease to support interpretation of clinical results and the related causalities.

METHODS

Eight stent system types of same dimensions were investigated (n=2). Parameters were the profile of stent delivery system (SDS), radiopacity, trackability and pushability, bending stiffness (flexibility) and axial stiffness of expanded stents, length change during expansion, radial force, crush resistance, strut thickness and general surface condition.

RESULTS

The trackability ranged from 0.237 to 0.920 N and the pushability was 47.9-67.6 %. The bending stiffness of SDS was between 108.42 and 412.68 N mm2. The length change during stent release to 5 mm was low, with one exception. The bending stiffness of the expanded stents was 2.73-41.67 N mm2. The normalized radial forces at 5 mm diameter ranged from 0.133 N/mm to 0.503 N/mm. During non-radial compression by 50 %, the forces were 3.07-8.42 N, with one exception (58.7 N). The strut thickness was 153-231 µm.

CONCLUSIONS

Large differences occurred for flexibility, radial force and length change during expansion. The data should be used when choosing the proper device for restoring vascular function.

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.

Randomized Controlled Trial of Conventional Versus MicroNet-Covered Stent in Carotid Artery Revascularization

OBJECTIVES

The aim of this study was to compare procedure-related ipsilateral cerebral embolism with a conventional (Acculink, Abbott Vascular) versus a MicroNet-covered (CGuard, InspireMD) stent in carotid artery stenting (CAS).

BACKGROUND

The MicroNet-covered stent may reduce periprocedural cerebral embolism in CAS, but level 1 evidence is lacking.

METHODS

A total of 100 consecutive patients were randomized 1:1 to filter-protected CAS using the Acculink or the CGuard device. The study was powered for its primary endpoint of at least 50% reduction in ipsilateral diffusion-weighted magnetic resonance imaging lesion average volume 48 hours postprocedure (blinded external core laboratory analysis).

RESULTS

The baseline characteristics of the study groups were similar. Eighty-two (total volume = 18,212 mm³) diffusion-weighted magnetic resonance imaging postprocedural cerebral lesions occurred in 26 Acculink-treated patients and 45 lesions (total volume = 3,930 mm³; 78.4% reduction) in 25 CGuard-treated patients. New cerebral lesion average volume was 171 mm³ vs 73 mm³ (P = 0.017) per affected patient and 222 mm³ vs 84 mm³ (P = 0.038) per lesion (Acculink vs CGuard). In lesion-affected patients, the average sum of lesion volumes was 701 mm³ vs 157 mm³ (P = 0.007). The Acculink significantly increased the risk for multiple (≥5) cerebral lesions (relative risk: 7.8; 95% CI: 1.3-14.9; P = 0.021). At 30 days, new permanent (fluid-attenuated inversion recovery) lesion prevalence was 3:1 (P < 0.001), with total permanent lesion volume 7,474 mm³ vs 574 mm³ (92.3% reduction with the CGuard). There were 6 vs 0 new ipsilateral lesions (P = 0.030) and 2 versus 0 strokes.

CONCLUSIONS

The MicroNet-covered stent significantly reduced periprocedural and abolished postprocedural cerebral embolism in relation to a conventional carotid stent. This is consistent with the MicroNet-covered stent's sustained embolism prevention, translating into cerebral protection not only during but also after CAS. The present findings may influence decision making in carotid revascularization. (The SIBERIA Trial [Acculink™ Versus CGuard™]; NCT03488199).

Carotid artery stenting: an update

PURPOSE OF REVIEW

To present the latest evidence about carotid artery stenting (CAS) including indications, safety, efficacy, and available equipment.

RECENT FINDINGS

The micromesh stent, a new stent design which offers excellent flexibility and embolic protection, has been associated with promising outcomes.

SUMMARY

CAS has emerged as a minimally invasive treatment method for carotid artery stenosis with comparable outcomes with surgical management. The implementation of new technology combined with operator experience has led to a paradigm shift; however, to date, no robust evidence exists about patient and lesion selection. Many studies are underway to clarify the technical aspects of CAS as well as the optimal treatment of carotid artery stenosis for each patient population.