Optical Coherence Tomography after Carotid Stenting: Rate of Stent Malapposition, Plaque Prolapse and Fibrous Cap Rupture According to Stent Design

Mid-Term Results of an Italian Multicentric Experience with the RoadsaverTM Dual-Layer Carotid Stent System

BACKGROUND

Carotid artery stenting (CAS) using first-generation single-layer stents is widely accepted as a good alternative to standard carotid endarterectomy (CEA) but it is associated with worse outcomes in terms of both plaque prolapse and cerebral embolization.

AIM

To evaluate the perioperative and midterm outcomes of CAS using the new-generation RoadsaverTM dual-layer micromesh-covered carotid stent.

METHODS

Herein, we present the results of an observational, retrospective, multicentric study on non-consecutive patients who underwent the CAS procedure between January 2017 and December 2022 at three Italian, high-volume vascular surgery centers. The inclusion criteria were the patients' eligibility for the CAS procedure in accordance with the current Italian guidelines, and the implantation of a Roadsaver stent. Both symptomatic and asymptomatic patients were included in the study. The patients requiring reintervention for carotid restenosis following CEA were also included. Perioperative data regarding procedural success was defined as the successful implantation of the device in the desired position, less than 30% residual stenosis, and the absence of intraoperative neurological complications. The primary outcome was any adverse cerebrovascular event such as stroke or transient ischemic attack (TIA) during the procedure and/or after discharge. The secondary outcomes were the need for further intervention, and all-cause death following procedure.

RESULTS

Three-hundred-fifty-three (353) patients were included in our study; the mean age was 74.3 years. A total of 5.9% of the patients were symptomatic on their operated side, while 7.3% had contralateral carotid occlusion. A cerebral embolic protection device (CPD) was employed in all patients. A total of 13.3% of the patients were operated on for restenosis after CEA Technical success was achieved in 96.9% of the cases with an intraoperative report of six TIAs (1.7%) and six ipsilateral strokes (1.7%). The mean hospital stay was 1.8 days. The thirty-day follow up showed one TIA and one more stroke. At the mean 35-month follow-up time, the primary outcome was present in six patients (1.7%), where four TIAs (1.1%) and two strokes (0.5%) were reported. Restenosis occurred in five patients (1.4%). Death for any cause was reported in 11 patients (3.1%).

CONCLUSIONS

As most recent, high-quality studies show, the CAS procedure with second-generation devices such as the Roadsaver stent is safe and effective in preventing carotid-related cerebrovascular events in both symptomatic and asymptomatic patients. The intraoperative and postoperative cerebrovascular complication rate in high volume centers is very low, ensuring confidence in its employment for the CAS procedure along with a CPD as a valid alternative to CEA.

Effect of plaque morphological characteristics on the outcomes of carotid artery stenting

Carotid artery stenting (CAS) represents today an accepted option for the treatment of severe carotid artery stenosis. The evolution of materials, techniques, perioperative medical management and patients' selection, has allowed to progressively reduce CAS complications. However, the main drawback of CAS is still represented by the risk of cerebral embolization, that may occur during several steps of the procedure and also in the early postoperative period. Preoperative carotid plaque morphological characteristics may have a great role in determining the risk of embolization during CAS. This review summarizes the current knowledge on carotid plaque characteristics that may influence the risk of complication during CAS. This information may be important for the optimization of CAS patients' selection and adaptation of the materials and techniques.

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.

Novel Imaging-Based Biomarkers for Identifying Carotid Plaque Vulnerability

Carotid artery disease has traditionally been assessed based on the degree of luminal narrowing. However, this approach, which solely relies on carotid stenosis, is currently being questioned with regard to modern risk stratification approaches. Recent guidelines have introduced the concept of the "vulnerable plaque," emphasizing specific features such as thin fibrous caps, large lipid cores, intraplaque hemorrhage, plaque rupture, macrophage infiltration, and neovascularization. In this context, imaging-based biomarkers have emerged as valuable tools for identifying higher-risk patients. Non-invasive imaging modalities and intravascular techniques, including ultrasound, computed tomography, magnetic resonance imaging, intravascular ultrasound, optical coherence tomography, and near-infrared spectroscopy, have played pivotal roles in characterizing and detecting unstable carotid plaques. The aim of this review is to provide an overview of the evolving understanding of carotid artery disease and highlight the significance of imaging techniques in assessing plaque vulnerability and informing clinical decision-making.

Optical Coherence Tomography in Cerebrovascular Disease: Open up New Horizons

Optical coherence tomography (OCT), based on the backscattering or reflection of near-infrared light, enables an ultra-high resolution of up to 10 μm. The successful application of OCT in coronary artery diseases has sparked increasing interest in its implementation in cerebrovascular diseases. OCT has shown promising potential in the atherosclerotic plaque structure characterization, plaque rupture risk stratification, pre-stenting and post-stenting evaluation, and long-term follow-up in extracranial and intracranial atherosclerotic stenosis (ICAS). In hemorrhagic cerebrovascular diseases, OCT plays an important role in the structure evaluation, rupture risk stratification, and healing and occlusion evaluation following initial treatment in intracranial aneurysms (IAs). In this study, we summarized the applications of OCT in the diagnosis, treatment, and follow-up of cerebrovascular diseases, especially in ICAS and IAs. The current limitations and future directions of OCT in the endovascular treatment of cerebrovascular diseases were also discussed.

The Height and Mobility of Protruding Plaque After Carotid Artery Stenting Are Associated with Postoperative Ischemic Lesions

BACKGROUND

Tissue protrusion (TP) is a possible cause of cerebral infarction after carotid artery stenting (CAS). Using optical frequency domain imaging (OFDI) and angioscopy, we investigated the relationship between the morphological features of TP and postoperative new ischemic lesions on magnetic resonance imaging (MRI)-diffusion weighted imaging (DWI) after CAS.

METHODS

Fifty patients who underwent CAS and subsequent poststenting intravascular evaluation using both OFDI and angioscopy were included. CAS was performed for proximal protection via the femoral artery approach, and intravascular evaluation with OFDI and angioscopy were performed after stent placement. We compared the background and poststenting intravascular findings between patients with and without postoperative new ischemic lesions on MRI-DWI.

RESULTS

TP was observed in 42 patients (84%), and postoperative new ischemic lesions on MRI-DWI were observed in 32 patients (64%). The frequency of TP did not differ between the 2 groups, but the height of TP was higher in the DWI-positive group (0.62 mm vs. 0.29 mm, P = 0.0028), and mobile TP was observed only in the DWI-positive group. The height of TP (P = 0.023) was an independent predictor of new periprocedural ischemic brain lesions after CAS, and its cut-off value for mobility was 0.55 mm on the receiver operating characteristic curve (area under the curve, 0.93).

CONCLUSIONS

The height of TP on OFDI and mobile-TP on angioscopy after CAS were associated with postoperative new ischemic lesions on MRI-DWI. The intravascular evaluation using OFDI and angioscopy could be helpful for a detailed evaluation of TP.

Safety and Efficacy of Carotid Artery Stenting with the CGuard Double-layer Stent in Acute Ischemic Stroke

BACKGROUND

Double-layer stents show promising results in preventing periinterventional and postinterventional embolic events in elective settings of carotid artery stenting (CAS). We report a single-center experience with the CGuard stent in the treatment of acute ischemic stroke (AIS) due to symptomatic internal carotid artery (ICA) stenosis or occlusion with or without intracranial occlusion.

METHODS

We retrospectively analyzed all patients who received a CGuard stent in the setting of AIS at our institution. Neuroimaging and clinical data were analyzed with the following primary endpoints: technical feasibility, acute and delayed stent occlusion or thrombosis, distal embolism, symptomatic intracranial hemorrhage (sICH) and functional outcome at 3 months.

RESULTS

In 33 patients, stenting with the CGuard was performed. Stent deployment was successful in all patients (28 with tandem occlusions, 5 with isolated ICA occlusion). Transient acute in-stent thrombus formation occurred in three patients (9%) without early stent occlusion. Delayed, asymptomatic stent occlusion was seen in 1 patient (3%) after 49 days. Asymptomatic periinterventional distal emboli occurred in 2 patients (6%), 1 patient experienced a transient ischemic attack 79 days after the procedure and 1 patient (3%) developed sICH. Favorable clinical outcome (mRS 0-2) at 3 months was achieved in 12 patients (36%) and the mortality rate was 24%.

CONCLUSION

The CGuard use in emergencies was technically feasible, the safety has to be confirmed by further multicentric studies.

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.

A Parametric Study of Flushing Conditions for Improvement of Angioscopy Visibility

During an angioscopy operation, a transparent liquid called dextran is sprayed out from a catheter to flush the blood away from the space between the camera and target. Medical doctors usually inject dextran at a constant flow rate. However, they often cannot obtain clear angioscopy visibility because the flushing out of the blood is insufficient. Good flushing conditions producing clear angioscopy visibility will increase the rate of success of angioscopy operations. This study aimed to determine a way to improve the clarity for angioscopy under different values for the parameters of the injection waveform, endoscope position, and catheter angle. We also determined the effect of a stepwise waveform for injecting the dextran only during systole while synchronizing the waveform to the cardiac cycle. To evaluate the visibility of the blood-vessel walls, we performed a computational fluid dynamics (CFD) simulation and calculated the visible area ratio (VAR), representing the ratio of the visible wall area to the total area of the wall at each point in time. Additionally, the normalized integration of the VAR called the area ratio (ARVAR) represents the ratio of the visible wall area as a function of the dextran injection period. The results demonstrate that the ARVAR with a stepped waveform, bottom endoscope, and three-degree-angle catheter results in the highest visibility, around 25 times larger than that under the control conditions: a constant waveform, a center endoscope, and 0 degrees. This set of conditions can improve angioscopy visibility.

Optical Coherence Tomography Evaluation of Carotid Artery Stenosis and Stenting in Patients With Previous Cervical Radiotherapy

Objectives

Cervical radiotherapy can lead to accelerated carotid artery stenosis, increased incidence of stroke, and a higher rate of in-stent restenosis in irradiated patients. Our objective was to reveal the morphological characteristics of radiation-induced carotid stenosis (RICS) and the stent–vessel interactions in patients with previous cervical radiotherapy by optical coherence tomography (OCT).

Materials and Methods

Between November 2017 and March 2019, five patients with a history of cervical radiotherapy were diagnosed with severe carotid artery stenosis and underwent carotid artery stenting (CAS). OCT was conducted before and immediately after the carotid stent implantation. Two patients received OCT evaluation of carotid stenting at 6- or 13-month follow-up.

Results

The tumor types indicating cervical radiotherapy were nasopharyngeal carcinoma (n = 3), cervical esophageal carcinoma (n = 1), and cervical lymphoma (n = 1). The median interval from the radiotherapy to the diagnosis of RICS was 8 years (range 4–36 years). Lesion characteristics of RICS were detected with heterogeneous signal-rich tissue, dissection, and advanced atherosclerosis upon OCT evaluation. Post-interventional OCT revealed 18.2–57.1% tissue protrusion and 3.3–13.8% stent strut malapposition. Follow-up OCT detected homogeneous signal-rich neointima and signal-poor regions around stent struts. In the patient with high rates of tissue protrusion and stent strut malapposition, the 6-month neointima burden reached 48.9% and microvessels were detected.

Conclusion

The morphological features of RICS were heterogeneous, including heterogeneous signal-rich tissue, dissection, and advanced atherosclerosis. Stenting was successful in all 5 patients with severe RICS. One patient, with high rates of tissue protrusion and stent strut malapposition immediately after stenting, received in-stent neointimal hyperplasia at a 6-month follow-up.

1-Year Results From a Prospective Experience on CAS Using the CGuard Stent System: The IRONGUARD 2 Study

OBJECTIVES

The aim of this study was to evaluate the 1-year safety and efficacy of a dual-layered stent (DLS) for carotid artery stenting (CAS) in a multicenter registry.

BACKGROUND

DLS have been proved to be safe and efficient during short-term follow-up. Recent data have raised the concern that the benefit of CAS performed with using a DLS may be hampered by a higher restenosis rate at 1 year.

METHODS

From January 2017 to June 2019, a physician-initiated, prospective, multispecialty registry enrolled 733 consecutive patients undergoing CAS using the CGuard embolic prevention system at 20 centers. The primary endpoint was the occurrence of death and stroke at 1 year. Secondary endpoints were 1-year rates of transient ischemic attack, acute myocardial infarction, internal carotid artery (ICA) restenosis, in-stent thrombosis, and external carotid artery occlusion.

RESULTS

At 1 year, follow-up was available in 726 patients (99.04%). Beyond 30 days postprocedure, 1 minor stroke (0.13%), four transient ischemic attacks (0.55%), 2 fatal acute myocardial infarctions (0.27%), and 6 noncardiac deaths (1.10%) occurred. On duplex ultrasound examination, ICA restenosis was found in 6 patients (0.82%): 2 total occlusions and 4 in-stent restenoses. No predictors of target ICA restenosis and/or occlusion could be detected, and dual-antiplatelet therapy duration (90 days vs 30 days) was not found to be related to major adverse cardiovascular event or restenosis occurrence.

CONCLUSIONS

This real-world registry suggests that DLS use in clinical practice is safe and associated with minimal occurrence of adverse neurologic events up to 12-month follow-up.

Is it possible to prevent cerebral embolization by improving the design and technology of carotid stent implantation?

INTRODUCTION

The prevention of atherosclerotic plaque fragmentation during carotid artery stenting is a fundamental problem in decreasing the risk of disability of patients. The goal of this review is to clarify whether the stent design can have a decisive impact on the rate of intraoperative and postoperative complications.

AREAS COVERED

Different designs of the carotid stents are briefed and the advantages and disadvantages of different stent designs are discussed as well as the results of their clinical use. Various solutions are presented to reduce cerebral embolism during carotid artery stenting.

EXPERT OPINION

There is no conclusive evidence for the benefits of closed cell and hybrid stents. The stent design cannot completely resolve the problem of cerebral embolism. Most of the events of cerebral microembolism occur at the stages of stent delivery rather than protrusion of an atherosclerotic plaque in the long-term follow-up. Most likely, minimization of the risks for periprocedural and postprocedural strokes requires not only the new solutions in stent design as well as the corresponding delivery systems and brain embolic protection systems, but also the new strategies of preprocedural drug stabilization of the atherosclerotic plaque in the carotid artery. Abbreviations: CAS, carotid artery stenting; CE, carotid endarterectomy; DW-MRI, diffusion-weighted magnetic resonance imaging; ECA, external carotid artery; ICA, internal carotid artery; IVUS, intravascular ultrasound examination; OCT, optical coherence tomography.

Endovascular optical coherence tomography imaging in cerebrovascular disease

Endovascular optical coherence tomography (OCT) is the highest resolution imaging modality currently available with spatial resolution of 10 µm. Although originally developed for interventional cardiology, the ability to visualize the luminal environment and anatomy, along with the stent-vessel interaction could be of great utility for various cerebrovascular diseases, and the adoption of endovascular OCT imaging in the evolving field of interventional neuroradiology seems instinctive. The purpose of this study is to conduct a systematic review of the literature regarding applications of endovascular OCT in the diagnosis and treatment of cerebrovascular diseases. In addition, the authors report their institutional experience with the use of OCT in carotid atherosclerotic disease, cerebral aneurysms, and acute ischemic stroke. A systematic review of the literature was undertaken. Peer-reviewed articles were collected through MEDLINE, Embase, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) searches through March 2020. A total of 34 studies with 598 patients were included in the qualitative synthesis. These include 23 studies of carotid atherosclerotic disease, 7 studies of cerebral aneurysms, and 4 studies of non-aneurysmal posterior circulation pathology. OCT imaging was feasible in 94% of patients with 0.6% complication rate. Endovascular OCT appears to be safe and feasible, allowing clinicians to visualize stent-vessel interactions, aneurysmal healing, and vulnerable atherosclerotic plaque features. OCT carries great promise, however additional investigations are needed before any imposing statement can be made about the role of OCT in cerebrovascular imaging.

What's happening in carotid stent? A case report of prominent plaque protrusion after carotid artery stenting observed on angioscopy

Thromboembolic complications after carotid artery stenting (CAS) remain an unsolved problem, and several intravascular imaging tools have been proposed to clarify the mechanism of these complications. We report a case of intraprocedural plaque protrusion revealed by angioscopy. A 64-year-old woman underwent CAS for left carotid artery stenosis. After stent placement, optical frequency domain imaging demonstrated some plaque protrusion, and angioscopy showed prominent mobile plaque fragments protruding into the vessel between stent struts and confirmed the coverage of the protruded plaque after the overlapping stent was placed. Compared with other tools, angioscopy more clearly revealed plaque protrusion in the vessel after CAS.

Hemodynamic changes between different anatomically designed stents after carotid stenting: a prospective multicenter study

BACKGROUND

The aim of this study was to investigate differences in the dynamic changes and risk factors of hemodynamic depression (HD) between straight and tapered carotid stenting (SCS and TCS, respectively).

METHODS

A total of 148 and 167 patients were included in TCS and SCS groups in this study, respectively. All clinical data were collected and analyzed for differences in HD and primary endpoint events at 12 months.

RESULTS

The SCS procedure had a lower predilation rate and a higher incidence of intra- and postprocedure HD; furthermore, the decline in heart rate in the SCS procedure was higher in patients with intra- and postprocedure HD (P < 0.05). Right stenosis [odds ratio (OR) 1.67] and stent type (ev3) (OR 2.31) were confirmed as risk factors, and older age (> 70 years) was accompanied by a lower risk (OR 0.58; P < 0.05). The SCS procedure had a higher incidence of bradycardia and hypotension after 24 h and a longer duration of hypotension (P < 0.05). Stenosis (> 80%) (OR 1.68), the SCS procedure (OR 1.72), and alcohol intake (OR 2.38) were defined as risk factors. There was no difference in the complications or clinical endpoint events in either procedure, and the restenosis rate was lower in the TCS procedure (1.35% vs 5.42%).

CONCLUSION

Our results reveal that TCS has a lower incidence of HD and that intra- and postprocedure HD have different manifestations and risk factors.

Clinical considerations and recommendations for OCT-guided carotid artery stenting

Introduction: Optical Coherence Tomography (OCT) is an intravascular imaging providing high-resolution images of morphological features of arterial wall. Nowadays, OCT is an accepted intravascular modality to study coronary arteries, stent implantation, and vessel injury. In the last decade, an increasing interest have been focused on the application of OCT in carotid arteries.Areas covered: Literature evidence in the application of OCT in carotid arteries still remains debated. So far, OCT has been used as a research tool, aiming to evaluate atherosclerotic plaques' features and stents' behavior after implantation. This paper is intended to summarize clinical evidences and practices in the use of OCT in carotid arteries district and during CAS procedures. Literature review was completed via Pubmed search using Keywords.Expert opinion: CAS is a safe and effective procedure when performed by trained physicians with a tailored approach. In this scenario, ambiguous pictures at ultrasound, angiography, and IVUS might be clarified using OCT.By providing unprecedented microstructural information on atherosclerotic plaques, OCT may identify the features of vulnerable carotid plaque and, by identifying possible defects after stent implantation as malapposition and plaque prolapse, it may help the tailoring approach to CAS.

Carotid Artery Stenting in Asymptomatic Carotid Artery Stenosis: JACC Review Topic of the Week

The advance of therapies to reduce the stroke impact of asymptomatic carotid artery stenosis has proved difficult over the last decade. Disagreement concerning the underlying randomized control trials has limited entry into the care arena of endovascular therapies. Recently, advances in percutaneous therapies for carotid artery disease have been reported and provide a substantial database supporting the further incorporation of endovascular-based therapies in patients who need revascularization and meet selection criteria. With a second randomized control trial now published, it is time for a re-evaluation of endovascular therapy as a component of carotid artery care. This review describes the advances in the field in the last 5 years, clarifying the current position of these therapies in the care of the patient with asymptomatic carotid artery disease.

Optical coherence tomography evaluation of vertebrobasilar artery stenosis: case series and literature review

BACKGROUND

Intracranial vertebrobasilar artery stenosis is an important cause of ischemic stroke. With its high resolution, intravascular optical coherence tomography (OCT) provides detailed assessment of vessel wall features. It is widely applied to identify high-risk plaque in the cardiovascular system, but its use in the intracranial artery has been limited.

OBJECTIVE

To explore, in this pilot study, the usefulness of OCT in imaging of the intracranial artery wall.

METHODS

Between November 2017 and July 2018, four patients with severe intracranial vertebrobasilar artery stenosis were enrolled for preintervention OCT evaluation of the lesion artery. Stenosis was present in the basilar artery in one case and in the intracranial vertebral artery in three cases.

RESULTS

OCT images of the lesions showed various features of plaque vulnerability, such as intraluminal thrombus, lipid-rich plaque with plaque rupture, thin fibrous cap, macrophage accumulations, and a mixed lesion with dissecting aneurysm. In view of the OCT findings, all patients received balloon angioplasty and stent implantation.

CONCLUSIONS

These cases describe the successful implementation of OCT in intracranial vertebrobasilar artery stenosis. No side effects were seen during the OCT imaging. This technology may help in the diagnosis and treatment of cerebrovascular disease.

Cholesterol Crystals are Associated with Carotid Plaque Vulnerability: An Optical Coherence Tomography Study

OBJECTIVE

Vulnerable carotid plaque is associated with cerebrovascular events. Cholesterol crystals are often seen in the atherosclerotic plaques. However, the potential role of cholesterol crystals in carotid plaques destabilization is unknown. We aimed to identify the association between cholesterol crystals and carotid plaque vulnerability.

METHODS

Optical coherence tomography assessment of carotid plaque was performed in 95 patients. Clinical characteristics and plaque morphology were examined. The differences in plaque characteristics (thrombus, calcification, neovascularization, and macrophage accumulations) and clinical parameters (age, symptom, coronary heart disease, total cholesterol, triglycerides, and C-reactive protein) between patients with or without cholesterol crystals were analyzed with multivariate logistic regression.

RESULTS

Among 66 patients with acceptable carotid atherosclerotic optical coherence tomography images, 16 were with and 50 were without cholesterol crystals. 56.3% patients (9 of 16) with cholesterol crystals had cerebrovascular ischemic symptom related to ipsilateral internal carotid artery, whereas only 26.0% patients (13 of 50) without cholesterol crystals had symptom (OR, 3.66; 95% CI, 1.13-11.82; P = .025). 75.0% of the plaques with cholesterol crystals had concomitant macrophage accumulation (OR, 4.14; 95% CI, 1.17-14.65; P = .04). In segments with cholesterol crystals, a higher presence of calcification could be demonstrated compared to those without cholesterol crystals (62.5% versus 32.0%, P = .03). 70.0% plaques with cholesterol crystals and calcification were classified as symptomatic plaques (OR, 6.38; 95% CI, 1.46-27.91; P = .01). No association between plaque rupture and cholesterol crystals was identified. Multivariate logistic regression showed that age and macrophage accumulation were independently associated with cholesterol crystals.

CONCLUSIONS

Carotid atherosclerotic plaques with cholesterol crystals were more likely to have concomitant macrophage and calcification accumulations. Patients with cholesterol crystals plaque experienced more cerebrovascular symptoms. Thus, cholesterol crystals, especially together with macrophage and calcification, may serve as an important component of venerable carotid plaques.

A meta-analysis of the effect of stent design on clinical and radiologic outcomes of carotid artery stenting

OBJECTIVE

Procedural characteristics, including stent design, may influence the outcome of carotid artery stenting (CAS). A thorough comparison of the effect of stent design on outcome of CAS is thus warranted to allow for optimal evidence-based clinical decision making. This study sought to evaluate the effect of stent design on clinical and radiologic outcomes of CAS.

METHODS

A systematic search was conducted in MEDLINE, Embase, and Cochrane databases in May 2018. Included were articles reporting on the occurrence of clinical short- and intermediate-term major adverse events (MAEs; any stroke or death) or radiologic adverse events (new ischemic lesions on postprocedural magnetic resonance diffusion-weighted imaging [MR-DWI], restenosis, or stent fracture) in different stent designs used to treat carotid artery stenosis. Random effects models were used to calculate combined overall effect sizes. Metaregression was performed to identify the effect of specific stents on MAE rates.

RESULTS

From 2654 unique identified articles, two randomized, controlled trials and 66 cohort studies were eligible for analysis (including 46,728 procedures). Short-term clinical MAE rates were similar for patients treated with open cell vs closed cell or hybrid stents. Use of an Acculink stent was associated with a higher risk of short-term MAE compared with a Wallstent (risk ratio [RR], 1.51; P = .03), as was true for use of Precise stent vs Xact stent (RR, 1.55; P < .001). Intermediate-term clinical MAE rates were similar for open vs closed cell stents. Use of open cell stents predisposed to a 25% higher chance (RR, 1.25; P = .03) of developing postprocedural new ischemic lesions on MR-DWI. No differences were observed in the incidence of restenosis, stent fracture, or intraprocedural hemodynamic depression with respect to different stent design.

CONCLUSIONS

Stent design is not associated with short- or intermediate-term clinical MAE rates in patients undergoing CAS. Furthermore, the division in open and closed cell stent design might conceal true differences in single stent efficacy. Nevertheless, open cell stenting resulted in a significantly higher number of subclinical postprocedural new ischemic lesions detected on MR-DWI compared with closed cell stenting. An individualized patient data meta-analysis, including future studies with prospective homogenous study design, is required to adequately correct for known risk factors and to provide definite conclusions with respect to carotid stent design for specific subgroups.

Impact of plaque dilation before carotid artery stent deployment

OBJECTIVE

Plaque stability is of utmost importance for stroke prevention in the perioperative period (within 24 hours) following carotid artery stenting (CAS). Although carotid plaque is entrapped between stent struts after stent deployment, postdilation can cause a scissoring effect on the plaque, increasing the risk of postprocedural embolic events due to plaque prolapse. Maximum carotid plaque dilation before stent deployment may reduce this risk. This study analyzed the effect of maximum dilation of the carotid plaque before stent deployment (max-pre-SD) or after stent deployment (post-SD) on macroscopic plaque debris, hemodynamic depression (HD), and immediate major adverse events.

METHODS

This prospective nonrandomized multicenter study analyzed patients treated for carotid artery stenosis with CAS from January 2014 to August 2016. Clinical and morphologic characteristics and operative details were analyzed with logistic regression analysis for macroscopic debris and HD. The number of microembolic signals (MESs) was assessed by transcranial Doppler and analyzed.

RESULTS

A total of 309 patients were enrolled and treated with standard CAS performed using a proximal occlusion cerebral embolic protection device; 149 received max-pre-SD and 160 were treated with post-SD. Technical success was achieved in 100% of cases. Macroscopic debris and HD were significantly different between the two groups in favor of max-pre-SD (P < .001). A significant difference in intraprocedural MESs between the groups was detected. Compared with post-SD, max-pre-SD significantly reduced mean MES counts (8.1% vs 68.1%; P < .001). Patients treated with post-SD had a significantly increased risk of MESs in the immediate postoperative period compared with patients treated with max-pre-SD (41.9% vs 1.3%; P < .001).This result was mainly due to the small number of events encountered. Patients treated with post-SD had a 12-fold increased risk of macroscopic debris collection (odds ratio [OR], 12.36; 95% confidence interval [CI], 5.68-26.87; P < .001) and an 18 times increase in HD risk (OR, 17.80; 95% CI, 5.27-60.17; P < .001) compared with patients treated with max-pre-SD. The heterogeneous, mainly echolucent plaque type significantly highly increased the risk of macroscopic debris (OR, 78.45; 95% CI, 8.70-707.09; P < .001) while acting as a protective factor against HD (OR, 0.02; 95% CI, 0.006-0.11; P < .001) along with echogenic or echolucent complex plaques with irregular surface plaque types (OR, 0.10; 95% CI, 0.031-0.336; P < .001). No significant differences between groups (max-pre-SD group and post-SD) were detected in immediate major adverse events (minor stroke, 2.0% and 2.5% [P = .461]; major stroke, 0% and 0.6% [P = .334], respectively).

CONCLUSIONS

Max-pre-SD seems to be a safe and feasible technical modification to the CAS procedure. Macroscopic debris, HD, and MESs are significantly reduced compared with CAS with post-SD. Further research with larger, randomized cohorts of patients is required to establish the superiority of this technical modification.

Efficacy of post-dilatation during carotid artery stenting for unstable plaque using closed-cell design stent evaluated by optical coherence tomography

BACKGROUND AND PURPOSE

This study aimed to use optical coherence tomography (OCT) to evaluate the efficacy of post-dilatation (PD) after stent placement for unstable plaques during carotid artery stenting (CAS) using closed-cell design stent.

MATERIALS AND METHODS

Twelve unstable carotid plaque lesions diagnosed by magnetic resonance imaging were evaluated by OCT during CAS. Pre-procedural minimum lumen diameter and area were 1.5 ± 0.6 mm and 2.6 ± 1.6 mm², respectively. The lesion was pre-dilated with balloon catheters (diameter 4.8 ± 0.3 mm), and closed-cell stent was deployed. PD was performed with balloon catheters of the same size as those used for pre-dilatation. Minimum lumen diameter/area and in-stent tissue prolapse volume after stent placement and after PD were calculated by 2-dimensional cross section images. The number of the stent cells showing tissue prolapse and malapposition after stent-placement and after PD were calculated by 3-dimensional analysis.

RESULTS

Compared to after stent placement, in-stent tissue prolapse volume (0.18 ± 0.10 to 0.22 ± 0.07 mm²/slice, P < 0.01), number of stent cells with any tissue prolapse (12.7 ± 8.2 to 21.0 ± 11.8%, P < 0.001) were significantly increased after PD; stent cells with ≥ 500-µm tissue prolapse (1.6 ± 1.1 to 0.7 ± 0.8%, P < 0.01) and stent malapposition (17.4 ± 7.2 to 14.0 ± 6.3%, P < 0.01) were significantly decreased.

CONCLUSIONS

PD after carotid stent placement caused increase in in-stent tissue prolapse volume and small tissue prolapse, however, the in-stent large tissue prolapse decreased, as the in-stent tissue prolapse may have been crushed into debris.

Thirty-day results from prospective multi-specialty evaluation of carotid artery stenting using the CGuard MicroNet-covered Embolic Prevention System in real-world multicentre clinical practice: the IRON-Guard study

AIMS

The aim of the present study was to evaluate periprocedural and 30-day outcomes in a prospective series of patients treated with the CGuard Embolic Prevention System (EPS).

METHODS AND RESULTS

From April 2015 to June 2016, a physician-initiated prospective multicentre study was performed in 200 consecutive patients admitted for protected carotid artery stenting (CAS) and treated using the CGuard EPS in twelve vascular centres. Outcome measures were: technical success, periprocedural (0-24 hours) and post-procedural (24 hours-30 days) major and minor strokes, death, acute myocardial infarction (AMI), transient ischaemic attack (TIA), and external carotid occlusion. In three centres, consecutive diffusion-weighted magnetic resonance cerebral imaging (DW-MRI) was performed ≤72 hours prior to and within 72 hours after the intervention. A distal embolic protection device was employed in 182 patients (91%). Technical success was 100%. No death, AMI or major stroke occurred periprocedurally. There were two TIAs and five periprocedural minor strokes (2.5%), including one thrombosis solved by surgery. In the remaining patients (199/200; 99.5%) one-month follow-up duplex ultrasound revealed optimal technical results. Post-procedural clinical follow-up was uneventful. No external carotid artery occlusion occurred. New post-procedural DW-MRI lesions were detected in 12 patients out of 61 (19.6%), including bilateral in five (8.2%) and isolated ipsilateral in six (9.8%), whereas one patient (1.6%) had contralateral only lesions.

CONCLUSIONS

Multicentre multi-specialty use of the CGuard EPS in routine clinical practice was associated with no major periprocedural neurologic complications and a total elimination of post-procedural neurologic complications by 30 days.

Perspective review on applications of optics in cerebral endovascular neurosurgery

Cerebral endovascular neurosurgery has transformed the way we manage cerebrovascular disease. Several landmark trials have demonstrated the effectiveness of endovascular techniques leading to continued technological development and applications for various diseases. The utilization of optical technologies and devices is already underway in the field of endovascular neurosurgery. We discuss the contemporary paradigms, challenges, and current optical applications for the most common cerebrovascular diseases: carotid atherosclerotic disease, cerebral aneurysms, intracranial atherosclerosis, and dural arteriovenous fistulas. We also describe needs-based opportunities for future optical applications, with the goal of providing researchers a sense of where we feel optical technologies could impact the way we manage cerebral disease.

Is optical coherence tomography a coherent strategy for carotid artery stenting?

Optical coherence tomography (OCT) is rarely necessary to guide clinical decisions about the appropriateness of carotid revascularization. For carotid artery stenting (CAS), computed tomography angiography is the best imaging tool to assess arch, carotid, and lesion-specific anatomy, including vessel dimensions and calcification. OCT is a coherent strategy after CAS to assess ambiguous angiographic findings and to guide appropriate therapy for dissection, thrombosis, and plaque prolapse.

Evaluation of spatial distribution and characterization of wall shear stress in carotid sinus based on two-dimensional color Doppler imaging

Objective

This study aims to use a wall shear stress (WSS) quantitative analysis software to analyze and evaluate the carotid sinus WSS spatial distribution and characteristics in intima-media thickness (IMT) normal and thickening group by using two-dimensional color doppler flow imaging (CDFI) so as to assist clinicians to predict the location and risk of plaque formation.

Methods

According to IMT, 50 subjects was selected as IMT thickening group and 50 subjects as IMT normal group from subjects who had a carotid ultrasound examination in Shanghai East hospital during October 2016 to October 2017. This study presents the spatial distribution of the carotid sinus WSS based on the WSS quantitative analysis software and compared the spatial distribution and characteristics of the carotid sinus WSS between IMT thickening group and IMT normal group through two- and three-dimensional WSS maps and a fused WSS image.

Results

The distributional regularity of WSS in both two group was: carotid sinus < common carotid artery (CCA) < internal carotid artery (ICA) and posterior-interior wall of the carotid sinus < the anterior-lateral wall of the carotid sinus. Furthermore, the WSS of CCA, ICA, the anterior-lateral proximal wall of the carotid sinus, the anterior-lateral distal wall of the carotid sinus, the posterior-interior proximal wall of the carotid sinus, and the posterior-interior distal wall of the carotid sinus in IMT thickening group was lower than the corresponding part of IMT normal group (P < 0.05).

Conclusion

In summary, this WSS quantitative analysis framework by two-dimensional CDFI can measure and reflect the carotid sinus WSS spatial distribution and characteristics more accurately and visually. As a convenient tool, it may be used for clinical prediction of the plaque formation in carotid sinus in the future.

Effect of Open- vs Closed-Cell Stent Design on Periprocedural Outcomes and Restenosis After Carotid Artery Stenting: A Systematic Review and Comprehensive Meta-analysis

Purpose:To compare periprocedural complications and in-stent restenosis rates associated with open- vs closed-cell stent designs used in carotid artery stenting (CAS). Methods: A systematic search was conducted to identify all randomized and observational studies published in English up to October 31, 2017, that compared open- vs closed-cell stent designs in CAS. Identified studies were included if they reported the following outcomes: stroke, transient ischemic attack (TIA), myocardial infarction (MI), hemodynamic depression, new ischemic lesions detected on imaging, and death within 30 days, as well as the incidence of in-stent restenosis. A random-effects model meta-analysis was employed. Model results are reported as the odds ratio (OR) and 95% confidence interval (CI). The I2 statistic was used to assess heterogeneity. Results: Thirty-three studies (2 randomized trials) comprising 20, 291 patients (mean age 71.3±3.0 years; 74.6% men) were included. Patients in the open-cell stent group had a statistically significant lower risk of restenosis ⩾40% (OR 0.42, 95% CI 0.19 to 0.92; I2=0%) and ⩾70% (OR 0.23, 95% CI 0.10 to 0.52; I2=0%) at a mean follow-up of 24 months. No statistically significant differences were identified for periprocedural stroke, TIA, new ischemic lesions, MI, hemodynamic depression, or death within 30 days after CAS. Sensitivity analysis of the 2 randomized controlled trials only did not point to any significant differences either. Conclusion: Use of open-cell stent design in CAS is associated with a decreased risk for restenosis when compared to the closed-cell stent, without significant differences in periprocedural outcomes.

Bioabsorbable Drug-Eluting Stent Versus Bare Metal Stent in Iliac Artery Evaluated by Optical Coherence Tomography: An In Vivo Study in Porcine

OBJECTIVE

This study aimed to compare, using optical coherence tomography (OCT), the outcomes of bioabsorbable drug-eluting stent with those of bare metal stent (BMS) following implantation in porcine iliac artery.

METHODS

After the placement of BMS and bioabsorbable drug-eluting stents, we used OCT and digital subtraction angiography to investigate stent appositions, arterial neointima, evagination, and restenosis at 1 and 3 months.

RESULTS

At 1 and 3 months after stent implantation, OCT study was performed to investigate 32 stents and 21 788 struts. Thirty-three malapposed struts were found in the bioabsorbable drug-eluting stent groups and 2 were found in BMS groups. The average neointimal thickness, area, and in-stent stenosis were significantly lower in bioabsorbable drug-eluting stents than in BMS, while the frequency of malapposed struts was higher in the bioresorbable drug-eluting stent groups. Average neointimal thickness was lower in bioabsorbable drug-eluting stents than in BMS at 1 (0.19 ± 0.09 vs 0.67 ± 0.75 mm; P < .001) and 3 months (0.21 ± 0.08 vs 1.52 ± 0.28 mm; P < .001).

CONCLUSION

Our study suggested that bioabsorbable drug-eluting stent is more effective in decreasing arterial restenosis than BMS in animal models.

Optimal platelet function test for in-stent tissue protrusion following carotid artery stenting

Purpose

To determine the best platelet function test for in-stent tissue protrusion following carotid artery stenting (CAS).

Methods

Patients who underwent CAS were recruited prospectively in this observational study. Combination of aspirin 100 mg/day and clopidogrel 75 mg/day was administered for a minimum of 7 days prior to procedure. Platelet aggregation was measured by light transmittance aggregometry (LTA) following stimulation by adenosine diphosphate (ADP), collagen, and thrombin receptor activating peptide (TRAP) and by the point of care assay, VerifyNow which measures aspirin and thienopyridine reaction units.

Results

In-stent tissue protrusion with maximum projection area of ≥1 mm² was detected by optical coherence tomography (OCT) in 10/28 (36%) patients. Baseline characteristics were not significantly different between the two in-stent size groups (i.e., ≥1 mm² vs. <1 mm²) but after stimulation by collagen at 10 and 20 μg/ml, platelet reactivity as measured by LTA was significantly higher in the ≥1 mm² group compared with the <1 mm² group. No other differences in platelet function were detected.

Conclusions

Collagen-induced platelet reactivity was related to in-stent tissue protrusion size following CAS.

Carotid stenting with double layered stents: Double trouble or double benefit?

The use of double layer (covered) stents during carotid artery stenting (CAS) appears to be safe; attenuation of plaque prolapse and distal embolization is reasonable but unproven. Double layer stents are commercially available in Europe but not in the United States; similar benefits might be obtained by implanting two self-expanding stents, to decrease the effective free cell area. Embolic protection devices (EPDs) are recommended in all CAS patients; the use of double layer stents does not eliminate the need for EPDs.