The capture of visible debris by distal cerebral protection filters during carotid artery stenting: Is it predictable?

The relationship between ultrasonographic plaque morphology and histopathology of embolic material captured in the protective filter during carotid artery stenting

PURPOSE

We aimed to correlate the presence or absence of embolic debris in filter-type embolic protection devices (EPD), which are frequently used during carotid artery stenting (CAS), with possible risk factors and ultrasonographic plaque features.

MATERIALS AND METHODS

Eighty patients, who underwent CAS using a filter-type EPD in the period between July 2016 and March 2019, were included in our study. The modified Gray-Weale classification (mGWC) subtypes obtained in the pre-procedural ultrasonographic examinations were recorded. In addition, other patient-related risk factors considered to be related to a distal embolism were recorded. After the procedure the filters were evaluated to detect and examine embolic debris in the pathology clinic. The presence and features of embolic debris in the filters were recorded.

RESULTS

In the examinations performed after CAS, embolic debris was macroscopically and microscopically detected in 22 (27%) and 34 (42.5%) of the filter-type EPDs, respectively. A significant correlation was found between the change in the mGWC category of stenotic plaques from type 5 to type 1 and the presence of embolic debris in the filter (p < 0.05). Furthermore, a significant relationship was found between stenotic segment length and the presence of embolic debris in the filter (p < 0.05). The presence of embolic debris was not statistically significantly related to predisposing risk factors for atherosclerosis (p > 0.05).

CONCLUSIONS

During CAS, the likelihood of the presence of embolic debris in the EPDs increases as mGWC categories change from type 5 to type 1 and as the length of the stenotic segment increases.

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).

Safety and efficacy of the SeparGate™ balloon-guiding catheter in neurointerventional surgery: Study protocol of a prospective multicenter single-arm clinical trial

Background

The balloon-guiding catheter (BGC) reportedly reduces the number of retrievals and occurrence of distal emboli, achieving superior revascularization results and improved clinical outcomes in acute stroke. This study will aim to examine the efficacy and safety of the new SeparGate™ BGC.

Design

This prospective multicenter single-arm clinical trial will aim to include 128 patients who fulfill its inclusion and exclusion criteria. All patients will receive endovascular interventional therapy with BGC assistance. The primary endpoint will be the immediate surgical success rate, while the secondary endpoint will be product performance. The safety evaluation will include serious adverse events such as puncture site hematoma and bleeding, cerebral vasospasm, vessel dissection, vessel perforation, air embolism, thrombus (acute or subacute), vessel occlusion, distal embolization, infection, adverse reaction to antiplatelet and anticoagulant drugs, intracranial hemorrhage, stroke, death, and device defect.

Discussion

The prospective multicenter trial will provide safety and efficacy information for the SeparGate™ BGC. Its findings will provide a clinical reference for endovascular adjuvant therapy of cerebrovascular disease.

Trial registration

ChiCTR1800014459.

Image-based analysis and simulation of the effect of platelet storage temperature on clot mechanics under uniaxial strain

Optimal strength and stability of blood clots are keys to hemostasis and in prevention of hemorrhagic or thrombotic complications. Clots are biocomposite materials composed of fibrin network enmeshing platelets and other blood cells. We have previously shown that the storage temperature of platelets significantly impacts clot structure and stiffness. The objective of this work is to delineate the relationship between morphological characteristics and mechanical response of clot networks. We examined scanning electron microscope images of clots prepared from fresh apheresis platelets, and from apheresis platelets stored for 5 days at room temperature or at 4 °C, suspended in pooled plasma. Principal component analysis of nine different morphometric parameters revealed that a single principal component (PC1) can distinguish the effect of platelet storage on clot ultrastructure. Finite element analysis of clot response to uniaxial strain was used to map the spatially heterogeneous distribution of strain energy density for each clot. At modest deformations (25% strain), a single principal component (PC2) was able to predict these heterogeneities as quantified by variability in strain energy density distribution and in linear elastic stiffness, respectively. We have identified structural parameters that are primary regulators of stress distribution, and the observations provide insights into the importance of spatial heterogeneity on hemostasis and thrombosis.

Cognitive Function After Carotid Artery Revascularization

Clinical investigations designed to contrast the efficacy of carotid endarterectomy (CEA) versus best medical therapy and CEA versus carotid artery stenting (CAS) in patients with carotid artery stenosis have been based on the traditional endpoints of stroke, myocardial infarction, and death. Cognitive function is being increasingly recognized as an important outcome measure that affects patient well-being and functional status. However, it has not been evaluated systematically in the context of carotid revascularization. A decline in cognitive function could occur from microembolic ischemia during surgical dissection (CEA) or intravascular instrumentation (CAS). It could also occur from hypoperfusion during clamping (CEA) or balloon dilation (CAS). Conversely, restoring perfusion could improve cognitive dysfunction that might have occurred from a state of chronic hypoperfusion. It is still unclear whether these complex interactions ultimately result in a net improvement or a deterioration of cognitive function. Furthermore, it is not known whether the 2 methods of carotid revascularization have a differential effect on cognitive outcomes. It is becoming increasingly clear, though, that there is a positive relationship between improvement in cognition and improvement in functional outcome of patients. Vascular surgeons will be well served to remain informed and even actively engaged in the development of this field if they wish to continue providing the high-quality, well-informed care they have traditionally offered to patients with carotid stenosis.

Brain Injury Secondary to Carotid Intervention

Causes of brain injury during endovascular carotid intervention are protean. Mechanisms of injury include embolic and hemodynamic events, acute carotid occlusions occurring through a variety of means, and the relatively rare contrast-induced encephalopathy.

Embolic injury may result from micro- and macroembolization and most commonly causes ischemic stroke when sufficiently severe. Hemodynamic injury may proceed from hemodynamic depression and hypoperfusion (which may result in watershed infarction) or the hyperperfusion syndrome, which may, if severe, result in hemorrhagic stroke.

Embolic and dynamic causes of stroke may either occur intraprocedurally or at a variable time after stent placement and may be co-related. Impaired clearance of emboli due to relative hypoperfusion may exacerbate their clinical relevance. Other causes of stroke include acute carotid occlusions, which most commonly occur procedurally due to flow-limiting spasm, acute dissection, and, if a filter-type cerebral protection device has been used, filter occlusion due to a large trapped embolic load. These scenarios may result in stroke if not recognized and dealt with appropriately. Acute stent thrombosis may occur within 24 hours of the procedure as a result of adverse hemodynamic factors or suboptimal patient response to procedural heparin and antiplatelet agents, or it may occur after the procedure, again perhaps as a result of suboptimal response to antiaggregate drugs.

A Microscopic and Biomarker Evaluation of Embolic Filter Debris Collected During Carotid Artery Stenting

PURPOSE

To evaluate and characterize debris retrieved from the cerebral embolic protection devices (EPDs) used during carotid artery stenting (CAS) and compare debris size, volume, tissue types, cellular composition, and protein biomarker expression in symptomatic and asymptomatic patients.

METHODS

Distal protection filters were retrieved from 22 consecutive patients (mean age 71.6 years, range 52-85; 16 men) undergoing elective CAS between July 2012 and February 2014 for >70% internal carotid artery stenosis (mean 85.4% ± 10.3%). Six patients were symptomatic. The debris within each EPD was visually characterized using stereomicroscopy and then processed for histology and immunohistochemistry. Biomarkers were immunohistochemically measured to evaluate plaque stability [matrix metalloproteinase-9 (MMP-9)], inflammation [glycoprotein CD68 and interleukin-6 (IL-6)], or phenotype [smooth muscle (SM)-actin and type IV collagen]. The immunohistochemical results were measured using semiquantitative grading criteria based on both staining intensity and distribution in the samples.

RESULTS

Macroscopic debris was visible in 5/22 EPDs; 3 of the 5 filters came from symptomatic patients. Microscopic debris was detected in all filters and ranged in size from 0.01 to 8.57 mm(2). Debris consisted of calcified, fibrous, and necrotic tissue, as well as fibrin and foam cells with no significant difference between the symptomatic and asymptomatic groups. There was no association between the degree or type of embolic material and stenosis severity, carotid tortuosity, calcium grade, soft plaque, or arch type. Symptomatic patients had a larger volume of debris (8.24 vs 0.58 mm(3), p<0.01), mean particle size (1.30 vs 0.32 mm(2), p<0.001), and expression of biomarkers IL-6 (2.17 vs 0.81, p<0.05), CD68 (2.00 vs 0.38, p<0.01), SM-actin (1.00 vs 0.25, p=0.055), type IV collagen (1.17 vs 0.25,p=0.082), and MMP-9 (1.00 vs 0.06, p<0.05).

CONCLUSION

Histological analysis revealed particulate embolization in all EPDs used during CAS. Symptomatic patients had a larger volume of embolic debris, mean particle size, and the biomarkers associated with inflammation, necrotic core, and diminished fibrous cap.

Management of extracranial carotid artery disease

Stroke is the third leading cause of death in developed nations. Up to 88% of strokes are ischemic in nature. Extracranial carotid artery atherosclerotic disease is the third leading cause of ischemic stroke in the general population and the second most common nontraumatic cause among adults younger than 45 years. This article provides comprehensive, evidence-based recommendations for the management of extracranial atherosclerotic disease, including imaging for screening and diagnosis, medical management, and interventional management.

Risk of distal embolization with stent retriever thrombectomy and ADAPT

Background

There is a discrepancy in clinical outcomes and the achieved recanalization rates with stent retrievers in the endovascular treatment of ischemic stroke. It is our hypothesis that procedural release of embolic particulate may be one contributor to poor outcomes and is a modifiable risk. The goal of this study is to assess various treatment strategies that reduce the risk of distal emboli.

Methods

Mechanical thrombectomy was simulated in a vascular phantom with collateral circulation. Hard fragment-prone clots (HFC) and soft elastic clots (SECs) were used to generate middle cerebral artery (MCA) occlusions that were retrieved by the Solitaire FR devices through (1) an 8 Fr balloon guide catheter (BGC), (2) a 5 Fr distal access catheter at the proximal aspect of the clot in the MCA (Solumbra), or (3) a 6 Fr guide catheter with the tip at the cervical internal carotid artery (guide catheter, GC). Results from mechanical thrombectomy were compared with those from direct aspiration using the Penumbra 5MAX catheter. The primary endpoint was the size distribution of emboli to the distribution of the middle and anterior cerebral arteries.

Results

Solumbra was the most efficient method for reducing HFC fragments (p<0.05) while BGC was the best method for preventing SEC fragmentation (p<0.05). The risk of forming HFC distal emboli (>1000 µm) was significantly increased using GC. A non-statistically significant benefit of direct aspiration was observed in several subgroups of emboli with size 50–1000 µm. However, compared with the stent-retriever mechanical thrombectomy techniques, direct aspiration significantly increased the risk of SEC fragmentation (<50 µm) by at least twofold.

Conclusions

The risk of distal embolization is affected by the catheterization technique and clot mechanics.

The role of embolic protection devices during carotid stenting prior to cardiac surgery in asymptomatic patients: empty filters?

OBJECTIVES

The purpose of this study was to analyze the debris captured in the distal protection filters used during carotid artery stenting (CAS).

BACKGROUND

CAS is an option available to high-risk patients requiring revascularization. Filters are suggested for optimal stroke prevention during CAS.

METHODS

From May 2005 to June 2007, filters from 59 asymptomatic patients who underwent CAS were collected and sent to a specialized laboratory for light-microscope and histological analysis. Peri- and postprocedural outcomes were assessed during 1-year follow-up.

RESULTS

On the basis of biomedical imaging of the filter debris, the captured material could not be identified as embolized particles from the carotid plaque. On histological analysis the debris consisted mainly of red blood cell aggregates and/ or platelets, occasionally accompanied by granulocytes. We found no consistent histological evidence of embolized particles originating from atherosclerotic plaques. Post-procedure, three neurological events were reported: two (3.4%) transient ischemic attacks (TIA) and one (1.7%) ipsilateral minor stroke.

CONCLUSION

The filters used during CAS in asymptomatic patients planned for cardiac surgery often remained empty. These findings may be explained by assuming that asymptomatic patients feature a different atherosclerotic plaque composition or stabilization through antiplatelet medication. Larger, randomized trials are clearly warranted, especially in the asymptomatic population.

The association of clinical variables and filter design with carotid artery stenting thirty-day outcome

OBJECTIVE

Patient and device selection are important for the success of carotid artery stenting (CAS). We hypothesize that distal protection filter (DPF) design characteristics that minimize blood flow resistance and maximize capture efficiency are associated with the absence of transient ischemic attack (TIA), stroke and neurologic-related death after 30 days.

METHODS

Records from 208 patients were reviewed retrospectively. Filter design characteristics were quantified previously in our laboratory. The association between risk factors and design characteristics with 30-day outcome was quantified using univariate analysis.

RESULTS

The 30-day all-cause stroke and death rate was 8.7% (asymptomatic: 7.7%, symptomatic: 10.6%). Five DPFs were used in the study: Accunet (41.3%), Angioguard (33.2%), FilterWire (24%), Emboshield (1%), and Spider (.5%). Diabetes (P = .04) and prior carotid endarterectomy (CEA, P = .03) were associated with adverse outcome. Prior stroke (P = .01) and prior CEA (P = .04) were significant for peri-procedural stroke. Design characteristics such as capture efficiency were associated with favorable outcomes.

CONCLUSIONS

Patients with prior CEA or stroke are more likely to have unfavorable CAS outcomes after 30 days. Filters with high capture efficiency may yield the best clinical results. Analysis of the effect of design characteristics on CAS outcome should aid the design of future devices.

[Filter content after carotid angioplasty and stenting: relation to ischemic lesions in diffusion-weighted imaging]

OBJECTIVES

To evaluate the relation between the material retrieved from distal filters after carotid angioplasty and stenting and the development of ischemic brain lesions in diffusion-weighted imaging (DWI). To determine the influence of demographic, clinical, and procedural variables in the pathogenesis of emboli and in ischemia after carotid angioplasty and stenting.

MATERIAL AND METHODS

We submitted the contents of the filters of 76 patients (60 men; mean age, 68.39 years; range, 46-82) who had undergone angioplasty and stenting for severe stenosis of the internal carotid artery for histologic analysis evaluating volume (< 1 λ = 0.001 ml = 1 μl; 1-10 λ; and > 10 λ) and the composition of the particles. All patients underwent DWI before and 24 hours after the procedure; we recorded whether lesions appeared and their number, size, and distribution. We correlated the findings with demographic, clinical, and procedural variables.

RESULTS

Symptoms were present before the procedure in 58 (76.3%) patients. Particles were present in 49 (64.5%) of the filters; most particles (77.5%) were 1 λ with a predominance of fibrin-platelet aggregates, cell remnants, and cholesterol crystals. DWI after the procedure detected lesions in 12 (15.8%) patients. We found no statistically significant correlation between filter contents and lesion detection after the procedure or between filter contents and other variables.

CONCLUSIONS

Ischemia after carotid angioplasty and stenting does not depend solely on the embolic load and its nature. We consider that the lower prevalence of postprocedural lesions in our series compared to others suggests that appropriate patient selection and experience minimize the negative influence of some variables like age in their development.

Routine Use of Debris Aspiration Before Retrieval of Distal Filter Protection Devices in Carotid Arterial Stenting: Analysis of Captured Debris and Evaluation of Clinical Results

BACKGROUND:

Distal filter protection allows for continuous cerebral perfusion during carotid artery stenting (CAS), although a higher risk of debris migrating into the cerebral arteries compared with other protection systems has been reported.

OBJECTIVE:

To improve the extent of debris capture, we used routine aspiration of blood located proximal to the filter in the internal carotid artery blood column before retrieval of the filter device.

METHODS:

Of 71 CAS procedures with distal filter protection, routine aspiration was performed in 41 procedures. The size and number of debris particles in each aspirated blood sample were measured under a stereoscopic microscope in 30 consecutive procedures with routine aspiration. Occurrence of periprocedural neurological events was compared between 41 procedures with routine aspiration and the other 30 without routine aspiration.

RESULTS:

In the aspirated blood, debris particles ≥500 μm and ≥1000 μm in the longest diameter were observed in 30 (100%) and 28 (93.3%) procedures, respectively. The number of particles ≥1000 μm was significantly larger in the second through fourth blood aspirates vs the first aspirate (P &lt; .05). Occurrence of periprocedural neurological events was significantly less frequent in the routine aspiration group (0 of 41 procedures) than in the conventional method group (7 of 30 procedures) (P &lt; .05).

CONCLUSION:

The use of routine aspiration during CAS with distal filter protection possibly reduced periprocedural neurological events by increasing the proportion of debris captured. To improve the capture of debris particles, at least 4 repeated aspirations are advisable during each CAS procedure.

V, Karakhanian WK, Caffaro RA. Técnica para quantificação e qualificação de material coletado em filtros de proteção cerebral

Contexto: A qualidade e a quantidade de partículas coletadas em filtros de proteção cerebral (FPC) durante angioplastia transluminal percutânea com stent (ATPS) podem esclarecer a importância desses dispositivos no tratamento de estenoses carotídeas. Objetivos: Analisar o conteúdo retido por FPC em pacientes submetidos a ATPS de artéria carótida interna com nova técnica de análise qualiquantitativa. Métodos: O material coletado em 10 FPC durante ATPS da bifurcação da carótida em pacientes com alto risco cirúrgico foi submetido a análise microscópica qualiquantitativa. Fotografias digitais das lâminas com material corado com hematoxilina e eosina foram analisadas com o programa Axio Vision LE Release 4.1, que calculou a área das partículas em micrômetros/metro quadrado (µm²). Resultados: O exame histopatológico evidenciou material em 100% dos filtros consistindo predominantemente de restos hemáticos, cristais de colesterol e cálcio. A área média de fragmentos coletados foi expressiva (1.570.310 µm²), e houve ampla variância desses valores. Conclusões: Os FPC coletam quantidade importante de fragmentos de placas de ateroma, e a grande variância nas quantidades de material coletado pode estar associada com a gravidade da lesão, motivo pelo qual se tornam relevantes estudos que utilizem técnica padronizada para a quantificação desses fragmentos e para a compreensão de seu real significado clínico.

Use of the Angiojet catheter to remove plaque outside a neuroprotection filter during carotid artery stenting

Carotid protection devices (CPD) during carotid artery stenting reduce the risk of cerebral embolization. The presence of debris outside the filter presents a problem as the material may be plaque or thrombus. We report a case that required the use of the Angiojet catheter to remove debris outside the CPD.

Volume and composition of emboli in neuroprotected stenting of the carotid artery

BACKGROUND AND PURPOSE

Periprocedural microembolization is a major and permanent risk for patients treated by angioplasty and stent placement of high-grade carotid stenoses. Little is known however about the characteristics and significance of these embolized particles. Our aim was to assess the volume and composition of debris captured by filters during carotid angioplasty and stent placement (CAS) of severe internal carotid artery (ICA) stenoses.

MATERIALS AND METHODS

Institutional review board approval and informed consent from all subjects were obtained. Two hundred one patients (mean age, 66.2 years; range, 35-82 years) with > or = 70% stenosis of the ICA underwent filter-protected CAS. Ultrastructural and semiquantitative analysis of the volume of filters was obtained. Multifactorial statistical analysis was performed to determine factors related to debris volume and composition.

RESULTS

Transient ischemic attack occurred in 6 patients (3%), and a major stroke, in 1 (0.5%). Debris was found in 117 filters (58.2%), with volume <1 lambda (0.001 mL) in 71%. The number of balloon dilations, age older than 65 years, and calcified plaques in pre-CAS angiography were significantly associated with the presence of particulates inside the filters (P < .03, P < .004, and P < .05, respectively).

CONCLUSIONS

Vessel wall and atheromatous plaques are the main source of microemboli during CAS. Embolization is mainly related to the number of balloon dilations during CAS. Planning a proper and individualized strategy for the procedure in each patient is essential to minimize the potential effects of manipulation during CAS.

Intraprocedural plaque protrusion resulting in cerebral embolism during carotid angioplasty with stenting

An 82-year-old man with an asymptomatic left high-grade carotid stenosis was treated with carotid artery stenting (CAS) under distal protection. The procedure consisted with predilation with a 5 x 40 mm percutaneous transluminal angioplasty (PTA) balloon, deployment of a 10 x 20 mm self-expandable stent, post-dilation with a 7 x 20 mm PTA balloon, and aspiration of debris with 60 ml of blood. The cervical carotid angiogram immediately after deflation of the distal blocking balloon demonstrated a small in-stent filling defect of the contrast medium that protruded from the anterior wall of the carotid artery. The following cranial carotid angiogram showed abrupt occlusion of the left middle cerebral artery (MCA). Because the in-stent lesion had vanished in the repeat study after recognition of this embolic event, it was suggested that an embolus had been liberated from the in-stent lesion, reaching the left MCA and obliterating it. In this case, the embolus was speculated to originate in the ruptured plaque, which protruded into the stent through the cells of the device and became liberated into the bloodstream. Attention should be paid so as not to overlook any plaque protrusion, which may be seen subsequently as a cerebral embolism on the angiogram obtained immediately after CAS.

In vitro performance assessment of distal protection devices for carotid artery stenting: effect of physiological anatomy on vascular resistance

PURPOSE

To assess in vitro the performance of 5 distal protection devices (DPDs) by evaluating the capture efficiency, pressure gradient, volume flow rate, and vascular resistance in the internal carotid artery (ICA).

METHODS

The time-averaged mean peak velocity in the common carotid artery and a blood-mimicking solution were used to simulate physiologICAl conditions in a silicone carotid phantom representing average human carotid artery geometry with a 70% symmetrICAl ICA stenosis. Five milligrams of dyed 200-microm nominal diameter polymer microspheres (larger than the pore size of the devices, except Spider RX, which was tested with 300-microm-diameter particles) were injected into the ICA. The percentages of particles missed after injection and lost during device retrieval were measured for the 5 devices (Spider RX, FilterWire EZ, RX Accunet, Angioguard XP, and Emboshield). The normalized pressure gradient, fraction of the volume flow rate, and vascular resistance in the ICA were calculated.

RESULTS

Spider RX captured the most particles (missing 0.06%, p<0.05) and yielded the smallest normalized pressure gradient increase (4.2%), the largest volume flow rate fraction (0.40), and the smallest vascular resistance in the ICA (272 mmHg/L x min(-1), a 5.4% increase with respect to initial conditions). Angioguard XP captured the fewest particles (missing 36.3%, p<0.05 except Emboshield) and resulted in the largest normalized pressure gradient increase (37%) in the ICA. RX Accunet produced the smallest volume flow rate fraction in the ICA (0.30) and the largest vascular resistance in the ICA (470 mmHg/ L x min(-1), an 82.2% increase). Emboshield migrated approximately 6 cm distal to the original position after particle injection. FilterWire EZ lost the fewest particles during retrieval (0.45%, p<0.05 except Accunet RX and Spider RX) and had the best overall performance with 200-microm emboli (p<0.05 except Accunet RX).

CONCLUSION

None of the devices tested completely prevented embolization. Overall, Spider RX had the best performance and is conjectured to have the best wall apposition of the devices tested. Vascular resistance should be considered a key filter design parameter for performance testing since it represents a quantitative estimation of the "slow-flow phenomenon." Our findings should be extrapolated cautiously to help interventionists choose the best device.

The type of embolic protection does not influence the outcome in carotid artery stenting

OBJECTIVES

The goal of this study was to review our experience with embolic protection devices (EPDs) during carotid artery stenting (CAS). Specifically, we aimed to verify their clinical effectiveness and to compare clinical outcomes between specific devices and types of EPDs.

METHODS

The CAS databases at four participating centers were reviewed. Adverse events were defined as death, stroke (>24 hours), or transient ischemic attack (TIA) (<24 hours). We compared the risk of procedural and 30-day events between patients treated with and without an EPD. We also compared these risks between different EPDs and between the different types of EPDs.

RESULTS

A total of 3160 CAS procedures using nine EPDs were analyzed. The risk of a procedural adverse event was 0.9% in protected and 2.3% in unprotected procedures (P = .12). Compared with the most frequently used device (FilterWire, Boston Scientific, Natick, Mass), there was no significant difference in the risk of procedural adverse events for any of the other EPDs. There was, however, an increased risk of 30-day adverse events with the Accunet (Abbott Vascular, Redwood, Calif) filter compared with the FilterWire (relative risk [RR] 2.67, confidence interval [CI] 1.41 to 5.04, P = .005). Pairwise comparison of proximal occlusion balloons to filters, distal occlusion balloons to filters, and proximal to distal occlusion balloons revealed no significant difference in the risk of procedural or 30-day adverse events. There was no significant difference in risk of procedural events between eccentric and concentric filters, however, the relative risk of eccentric compared with concentric filters at 30 days was 0.59 (unadjusted, CI 0.38 to 0.92, P = .04). This difference was still apparent after adjustment for risk factors (RR 0.61, CI 0.39 to 0.95, P = .06), but not after adjustment for risk factors and stent-type [(open-cell vs closed-cell) RR 0.76, CI 0.47 to 1.22, P = .51].

CONCLUSION

The use of EPDs is associated with a low risk of procedural adverse events. We were unable to detect significant differences in risks of procedural adverse events between different devices or types of devices. We speculate that the observed differences seen at 30 days are largely attributable to differences in stent-type used.

Does Free Cell Area Influence the Outcome in Carotid Artery Stenting?

OBJECTIVES

To identify if carotid stent design, especially free cell area, impacts on the 30-day rates for stroke, death and TIA after carotid artery stenting (CAS).

MATERIAL AND METHODS

A CAS database of 3179 consecutive CAS patients was retrospectively assessed. The distribution of neurological complications were analysed for association with the different stent types and designs. Events where subdivided into procedural and postprocedural events.

RESULTS

The overall combined rate of TIA, stroke and death was 2.8% at 30 days (late events 1.9%). The post-procedural event rate analyzed for differences stents varied from 1.2% using BSCI Carotid Wallstent to 5.9% using Medtronic Exponent. The late event rates varied from 1.2% to 3.4% for free cell areas <2.5mm(2) and >7.5mm(2) respectively (p<0.05). Post-procedural event rate was 1.3% for closed cells and 3.4% for open cells. All these differences were highly pronounced among symptomatic patients (p<0.0001).

CONCLUSIONS

After carotid stenting, complication rates vary according to stent type, free cell area and cell design. In the symptomatic population (and also in the total population), post-procedural complication rates are highest for the open cell types and increase with larger free cell area.

The evidence for cerebral protection: An analysis and summary of the literature

It has been considered likely that the majority of cerebral ischaemic episodes following carotid artery stenting are due to cerebral embolisation. It is intuitive therefore, to attempt to prevent these presumptive emboli, whether they are comprised of air or formed elements, from reaching the brain. Various pharmacological and mechanical solutions are being used. The available literature is hampered by comparisons against historical controls of unprotected CAS with many confounding variables that may influence outcome. There is no clinical Level-I evidence to support the use of protection devices but Level-III and Level-IV evidence suggest benefit.

Do device characteristics impact outcome in carotid artery stenting?

OBJECTIVES

The study was conducted to identify patient and procedural parameters that negatively impact the 30-day rates for stroke, death and transient ischemic attack (TIA) after carotid artery stenting (CAS) and that might be modified or further studied in future efforts to improve CAS.

METHODS

This was a retrospective investigation of a dual-center CAS database of 701 consecutive CAS patients (414 men; mean age, 72.4 +/- 8.4). A subset of patient-related, lesion-related, or procedure-related variables (age >or=80, left sided lesion, symptomatic, nicotine abuse, hypertension, diabetes mellitus, other peripheral vascular disease, hypercholesterolemia, embolic protection devices usage, predilation, ulcerated lesion, echolucent plaque, restenosis after surgery) were analyzed for association with occurrence of stroke, death, or TIA <or=30 days after CAS. The odds ratio (OR) and 95% confidence interval (CI) and P value were calculated for each variable to predict adverse outcome.

RESULTS

The overall combined rate of stroke, death, and TIA within this database was 3.7% at 30 days. In the total population of 701 patients, only the OR of 2.7 for hypercholesterolemia (95% CI, 1.0 to 7.3; P = .041) was found to be significant. Subgroup analysis of the 304 symptomatic patients (43%) showed that open-cell stent designs and concentric EPD designs yielded an OR of 4.1 (95% CI, 1.4 to 12, P = .0136) and 3.3 (95% CI, 1.016 to 10, P = .0525), respectively, for 30-day stroke/death/TIA within this database. Analysis of open-cell stent designs and concentric EPD designs in patients with echolucent lesions yielded an OR of 3.1 (95% CI,1.2 to 8.2, P = .0343) and 3.7 (95% CI, 1.3 to 10, P = .0174), respectively, for 30-day stroke/death/TIA.

CONCLUSIONS

We conclude that increased analysis of device design variables may be necessary. Particularly in symptomatic patients or with echolucent lesions, closed-cell design and eccentric filters seem superior. Prospective investigation comparing open-cell vs closed-cell stents and eccentric vs concentric filter devices may be warranted.

Patient selection for carotid stenting versus endarterectomy: A systematic review

Carotid artery stenting has emerged as an alternative to carotid endarterectomy for the treatment of severe extracranial carotid stenosis in patients with anatomic or clinical factors that increase their risk of complications with surgery, yet there remains a substantial amount of variability and uncertainty in clinical practice in the referral of patients for stenting vs endarterectomy. By undertaking a thorough review of the literature, we sought to better define which subsets of patients with "high-risk" features would be likely to preferentially benefit from carotid stenting or carotid endarterectomy. Although only a single randomized trial comparing the outcomes of carotid stenting with distal protection and endarterectomy has been completed, a wealth of observational data was reviewed. Relative to endarterectomy, the results of carotid stenting seem favorable in the setting of several anatomic conditions that render surgery technically difficult, such as restenosis after prior endarterectomy, prior radical neck surgery, and previous radiation therapy involving the neck. The results of stenting are also favorable among patients with severe concomitant cardiac disease. Carotid endarterectomy, alternatively, seems to represent the procedure of choice among patients 80 years of age or older in the absence of other high-risk features. Overall, existing data support the concept that carotid stenting and endarterectomy represent complementary rather than competing modes of therapy. Pending the availability of randomized trial data to help guide procedural selection, which is likely many years away, an objective understanding of existing data is valuable to help select the optimal mode of revascularization therapy for patients with severe carotid artery disease who are at heightened surgical risk.