A case of in-stent neoatherosclerosis 10 years after carotid artery stent implantation: observation with optical coherence tomography and plaque histological findings

Relationship between in-stent restenosis following carotid artery stenting and platelet reactivity to clopidogrel

OBJECTIVE

To analyze the relationship between in-stent restenosis (ISR) following carotid artery stenting (CAS) and platelet clopidogrel reactivity confirmed by the P2Y12 reaction unit (PRU) and inhibition rate (IR).

METHODS

We retrospectively analyzed 171 patients who underwent CAS with extracranial carotid stenosis from January 2016 to December 2019. Dual antiplatelet therapy with 100 mg aspirin and 75 mg clopidogrel was started ≥5 days before CAS. Clopidogrel resistance was measured with the PRU and IR the day before CAS. The ISR degree was classified into R1, R2, and R3 (moderate to severe luminal stenosis of ≥50% or occlusion) by carotid CT angiography after 24-30 months. The degree of quantitative association between platelet reactivity and ISR R3 was determined by the receiver operating characteristic curve method. The optimal cut-off values of PRU and IR were derived using the maximum Youden index.

RESULTS

There were 33 R3 degrees of ISR (19.3%) and nine ipsilateral ischemic strokes (5.3%). The PRU and IR were different between R1+R2 degrees (176.4±50.1, 27.5±18.7%) and R3 degree (247.5±55.0, 10.3±13.4%) (P<0.001). The areas under the curves of PRU and IR were 0.841 and 0.781, and the optimal cut-off values were 220.0 and 14.5%, respectively. Multivariate logistic regression analysis showed that PRU ≥220 and IR ≤14.5% were significant predictive factors for ISR R3 (P<0.001 and P=0.017, respectively). ISR R3 was independently associated with ipsilateral ischemic stroke after CAS (P=0.012).

CONCLUSIONS

High PRU (≥220) and low IR (≤14.5%) are related to ISR R3 following CAS, which may cause ipsilateral ischemic stroke.

Randomized Controlled Trial of Cilostazol Addition for In-Stent Restenosis After Carotid Artery Stenting

BACKGROUND

Restenosis after carotid artery stenting (CAS) is associated with the risk of developing ischemic stroke. We aimed to evaluate the inhibitory effect of cilostazol addition on in-stent restenosis (ISR) in patients treated with CAS.

METHODS

In a randomized, open-label, blind-end point trial, patients with symptomatic and asymptomatic carotid artery stenosis and scheduled for CAS were randomly assigned to adding cilostazol (50 or 100 mg, twice per day) on other antiplatelets from 3 days before CAS or not adding cilostazol. Concomitant use of other antiplatelets was unrestricted. ISR was diagnosed by a peak systolic velocity of at least 1.75 m/s on duplex ultrasonography. The primary outcome was incidence of ISR within 2 years after CAS. Secondary outcomes included occurrences of cardiovascular events or any death and hemorrhagic events.

RESULTS

Participants were recruited from December 2010 to September 2015. Although the sample size was initially set to be 900 (450 in each group), 631 patients (mean age 69.9 years, 558 men, 325 in the cilostazol, and 306 in the noncilostazol group) were included in the primary analysis. Within 2 years' follow-up, ISR occurred in 31 of 325 patients (cumulative incidence 10.8%) in the cilostazol group and 46 of 306 patients (19.6%) in the noncilostazol group (hazard ratio, 0.64 [95% CI, 0.41-1.0]; P=0.056). In the exploratory analysis, incidence of ISR beyond 30 days after CAS was lower in the cilostazol group than in the noncilostazol group (10.3% versus 19.3%; P=0.040). Incidences of cardiovascular events or any death and hemorrhagic events were similar between the groups (6.2% versus 6.7% and 2.3% versus 1.4%, respectively).

CONCLUSIONS

The addition of cilostazol to other antiplatelet agents could contribute to the reduction of ISR in the chronic stage of patients who underwent CAS, the authenticity of which depends on further studies with sufficient statistical power.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01261234.

Optical coherence tomography findings of balloon angioplasty/stenting for in-stent restenosis after carotid artery stenting

OBJECTIVES

The optimal therapeutic methods for in-stent restenosis (ISR) after carotid artery stenting (CAS) remains controversial. This study aimed to use optical coherence tomography (OCT) to evaluate the in-stent architectures during endovascular angioplasty/stenting for ISR.

MATERIALS AND METHODS

Six lesions of ISR after CAS were evaluated by OCT during endovascular angioplasty/stenting.

RESULTS

In one lesion, the OCT system could not be crossed because of elongation distal to the ISR lesion. In five lesions, pre-procedural OCT clearly revealed neointimal hyperplasia or neoatherosclerosis. The mean in-stent area stenosis was 84%. After regular balloon angioplasty, tissue compression and dissection of various sizes and layers were detected. After balloon angioplasty (with a mean balloon size of 5.4 mm), the minimum lumen area (from 1.7 ± 0.6 to 11.4 ± 5.3 mm2, p < 0.01) and the minimum in-stent area (12.7 ± 2.6 to 21.8 ± 5.0 mm2, p < 0.01) showed a significant increase. Additional stent was placed in one lesion that developed into a flap by dissection after balloon angioplasty. In another lesion in which sufficient dilatation was not achieved by balloon angioplasty, a major stroke occurred by acute occlusion of the ISR lesion 10 months later.

CONCLUSIONS

OCT can detect the in-stent architecture of ISR lesions after balloon angioplasty and additional stent placement. However, which dissection should be treated by additional stent remain problematic.

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.

Symptomatic atherosclerotic plaque progression in a first-generation carotid stent: management and 5-year clinical and imaging outcome-a case report

Background

Restenosis in first-generation (single-layer) carotid stents (FGS) is believed to represent an exaggerated healing response of (neo)intimal hyperplasia (NIH) formation. Rather than NIH, we describe symptomatic in-FGS unstable plaque (neo)atherosclerosis mandating re-revascularization. To halt continued plaque evolution, we propose a novel treatment strategy involving a microNet-covered stent (MCS, second-generation carotid stent) to sequestrate the plaque from the vessel lumen. A durable long-term result is documented using multi-modal imaging.

Case summary

With a seemingly optimal result of FGS (Precise) symptomatic carotid lesion revascularization followed by optimal medical therapy, a late (≥3 years) progressive in-stent restenosis (ISR) arose. At Year 11, crescendo ipsilateral transient ischaemic attacks occurred. Angiography showed an ulcerated tight lesion throughout stent length. Intravascular ultrasound (IVUS) virtual histology imaging revealed thin-cap fibroatheroma. Reintervention was performed under distal protection. Undersized balloon predilatation to insert a stent caused symptomatic no-flow, and aspiration catheter was used to reduce the filter load. A MCS (CGuard) was implanted and post-dilated to ensure full lumen gain; IVUS confirmed complete plaque sequestration. The optimal anatomic result remained unchanged throughout 5 years (ultrasound and computed tomography verification); this was accompanied by clinical cure.

Discussion

This is the first demonstration of in-FGS (neo)atherosclerosis resolution using an MCS to sequestrate and insulate the atherosclerotic plaque. We show that ISR may be underlined by atherosclerotic plaque progression via the FGS single-layer stent struts that may show vulnerable plaque phenotype and may be associated with cerebral ischaemia. The anatomically and clinically effective exclusion of the atherosclerotic plaque by an MCS enabled lasting, optimal endovascular reconstruction and clinical cure.

Case Report: A Cluster of Complications During Carotid Artery Stenting Managed With Peripheral, Coronary, and Imaging Techniques

We describe the case of a 72-year-old man with severe, asymptomatic in-stent restenosis detected 4 years after index carotid artery stenting (CAS). The patient was deemed at low risk and scheduled for re-angioplasty with a drug-coated balloon as per institution protocol. What at first seemed a simple case suddenly turned into a series of cerebral and vascular complications that were successfully managed with a mix of peripheral, coronary, and imaging techniques.

Atherosclerotic Plaque Tissue Characterization: An OCT-Based Machine Learning Algorithm With ex vivo Validation

There is a need to develop a validated algorithm for plaque characterization which can help to facilitate the standardization of optical coherence tomography (OCT) image interpretation of plaque morphology, and improve the efficiency and accuracy in the application of OCT imaging for the quantitative assessment of plaque vulnerability. In this study, a machine learning algorithm was implemented for characterization of atherosclerotic plaque components by intravascular OCT using ex vivo carotid plaque tissue samples. A total of 31 patients underwent carotid endarterectomy and the ex vivo carotid plaques were imaged with OCT. Optical parameter, texture features and relative position of pixels were extracted within the region of interest and then used to quantify the tissue characterization of plaque components. The potential of individual and combined feature set to discriminate tissue components was quantified using sensitivity, specificity, accuracy. The results show there was a lower classification accuracy in the calcified tissue than the fibrous tissue and lipid tissue. The pixel-wise classification accuracy obtained by the developed method, to characterize the fibrous, calcified and lipid tissue by comparing with histology, were 80.0, 62.0, and 83.1, respectively. The developed algorithm was capable of characterizing plaque components with an excellent accuracy using the combined feature set.

Carotid Geometry as a Predictor of In-Stent Neointimal Hyperplasia - A Computational Fluid Dynamics Study

BACKGROUND

Carotid angioplasty and stenting (CAS) is emerging as an alternative treatment for carotid stenosis, but neointimal hyperplasia (NIH) remains a drawback of this treatment strategy. This study aimed to evaluate the effect of variations of carotid bifurcation geometry on local hemodynamics and NIH.

METHODS AND RESULTS

Hemodynamic and geometric effects on NIH were compared between 2 groups, by performing computational fluid dynamics (CFD) simulations both on synthetic models and patient-specific models. In the idealized models, multiple regression analysis revealed a significant negative relationship between internal carotid artery (ICA) angle and the local hemodynamics. In the patient-derived models, which were reconstructed from digital subtraction angiography (DSA) of 25 patients with bilateral CAS, a low time-average wall shear stress (TAWSS) and a high oscillatory shear index (OSI) were often found at the location of NIH. Larger difference values of the OSI percentage area (10.56±20.798% vs. -5.87±18.259%, P=0.048) and ECA/CCA diameter ratio (5.64±12.751% vs. -3.59±8.697%, P=0.047) were detected in the NIH-asymmetric group than in the NIH-symmetric group.

CONCLUSIONS

Changes in carotid bifurcation geometry can make apparent differences in hemodynamic distribution and lead to bilateral NIH asymmetry. It may therefore be reasonable to consider certain geometric variations as potential local risk factors for NIH.

Calcification in original plaque and restenosis following carotid artery stenting

Background:

The relationship between calcification in primary plaque and recurrent stenosis after carotid artery stenting (CAS) is not established, but an inverse association with restenosis following carotid endarterectomy (CEA) has been suggested.

Methods:

We retrospectively analyzed 75 plaques of 109 consecutive CAS with regard to calcification, using the calcium score and shape, location, and other characteristics of original plaques together with stenting-related factors. CAS was performed in a standard fashion with an embolic protection device. Greater-than-moderate restenosis (≥50%) was assessed by peak systolic velocity (PSV) with duplex ultrasonography (≥130 cm/s, internal/common carotid or distal/proximal PSV ratio ≥2.0).

Results:

Univariate analysis revealed percentages of dyslipidemia treated with statins (P = 0.03), calcification in distal ICA (P = 0.02), and immediate residual stenosis (P = 0.02) were significantly higher in patients with greater-than-moderate restenosis, whereas calcification in carotid bulb and usage of open-cell stent were rather less frequent (P < 0.001 and P = 0.02, respectively). Multivariate logistic regression analysis showed that rarity of calcification in carotid bulb was a sole independent predictor for greater-than-moderate recurrent carotid stenosis 1 year after CAS (OR = 0.21, CI = 0.06–0.77, P = 0.02).

Conclusions:

Calcium score was not significantly related to restenosis at 1 year after CAS, as was previously found following CEA, though scarcity of calcification in carotid bulb was suggested as a predictor of in-stent restenosis. Compared to post-CEA restenosis, carotid plaque calcification may be inversely but tenuously associated with recurrent stenosis 1 year post-CAS. No other stenting factors (e.g., stent design, pre-/post-dilation, or protection devices) showed a significant association with recurrent stenosis post-CAS.

In-stent hypodense area at two weeks following carotid artery stenting predicts neointimal hyperplasia after two years

Introduction It has not been reported how long the follow-up study after carotid artery stenting (CAS) should be continued. The purpose of the present study is to clarify the dynamic change of the in-stent neointimal layer and residual arterial lumen by two years following CAS using three-dimensional computed tomography angiography (3D CTA) with volume rendering. Methods Thirty-six stented carotid arteries in 34 consecutive patients were examined by 3D CTA with volume rendering at two weeks and 3, 6, 12, 24 months of follow-up. Results An in-stent hypodense area could be detected in 10 of 36 (27.8%) carotid arteries at two weeks after CAS. In-stent hypodense areas gradually declined thereafter by three months. In the course of longer follow-up, the layer of the in-stent hypodense area (neointimal hyperplasia) continued to grow in size for up to 24 months. Patients with an in-stent hypodense area at two weeks have a thicker layer of neointimal hyperplasia at 24 months than patients without in-stent hypodense area at two weeks' follow-up. The predictive factors for growing neointimal hyperplasia at 24 months in multiple regression analysis are ulcer formation in pretreatment stenosis and the thickness of in-stent hypodense area at two weeks following CAS. Conclusion Our results suggest that follow-up study should be continued for a longer period even if in-stent restenosis could not be detected at one year following CAS. Especially in cases with ulcer formation in pretreatment stenosis and with a subacute in-stent hypodense area after CAS, longer follow-up is strongly recommended.

Restenosis after carotid artery stenting

As a common etiology for ischemic stroke, atherosclerotic carotid stenosis has been targeted by vascular surgery since 1950s. Compared with carotid endarterectomy, carotid angioplasty and stenting (CAS) is almost similarly efficacious and less invasive. These advantages make CAS an alternative in treating carotid stenosis. However, accumulative evidences suggested that the long-term benefit-risk ratio of CAS may be decreased or even neutralized by the complications related to in-stent restenosis (ISR). Therefore, investigating the mechanisms and identifying the influential factors of ISR are of vital importance for improving the long-term outcomes of CAS. As responses to intrinsic and extrinsic injuries, intimal hyperplasia and vascular smooth muscle cell proliferation have been regarded as the principle mechanisms for ISR development. Due to the lack of consensus-based definition and consistent follow-up protocol, the reported incidences of ISR after CAS varied widely among studies. These variations made the inter-study comparisons of ISR largely illogical. To eliminate restenosis after CAS, both surgery and endovascular procedures have been attempted with promising results. For preventing ISR, drug-eluting stents and antiplatelets have been proposed as potential solutions.