Thrombus Components Research Articles

Intracranial thrombus composition is associated with occlusion location and endovascular treatment outcomes: results from ITACAT multicenter study

BackgroundThe impact of thrombolytics directed towards different thrombus components regarding site of occlusion in combination with mechanical thrombectomy (MT) to achieve endovascular complete recanalization is unclear.MethodsRetrospective analysis of a prospective...

How the elastase-induced rabbit aneurysm heals following flow diverter treatment: a histopathological study.

Fibrin deposition is integral to thrombus formation and wound healing. The role of fibrin deposition and subsequent metabolism following flow diversion for aneurysm treatment remains poorly characterized. This study aimed to evaluate the role of fibrin in early thrombus organization after flow diverter treatment. Thirty-five elastase-induced aneurysms were induced in New Zealand white rabbits and subjected to endoluminal flow diversion treatment. The device-bearing arteries were harvested at 1, 3, and 6 months postimplantation and processed for histopathological examination, including a modified picro-Mallory stain (Carstairs method) to visualize fibrin and platelets, immunohistochemical targeting of smooth muscle actin (SMA), and H&E staining for conventional morphological evaluation. Quantitative analysis of tissue components was carried out using the Orbit Image Analysis software. The samples were also assessed qualitatively to investigate the morphology and location of fibrin and other thrombus components within the intra-aneurysmal thrombi. Statistical analyses were conducted using R software version 4.3.1. Fibrin constituted 27.9% of the thrombus tissue within the aneurysm sac for aneurysms harvested at 1 month, and this rate was significantly lower in the 3-month group (10.2%, p = 0.018). The proportion of blood cells within the sac was also notably higher in the 1-month group compared with other time points. The primary tissue filling the dome at 1 month (14/15, 93%) was an unorganized thrombus primarily composed of fibrin, platelets, and red blood cells. Conversely, aneurysms harvested at 1 month had the lowest collagen level (25.6%). However, collagen became the dominant tissue component within the aneurysm sac, accounting for 71.8% of tissue in the 3-month group (p = 0.007). There were no differences observed among the examined components between the 3-month and 6-month groups. On qualitative analysis, collagen-producing SMA-positive myofibroblasts were located near or in between fibrin molecules. Healed aneurysms exhibited myofibroblasts, collagen, and a well-organized fibrin network on the aneurysm neck. In contrast, unhealed aneurysms displayed a poorly organized fibrin network with scattered myofibroblasts at the neck area. These findings indicate that fibrin plays a foundational role in the gradual occlusion of aneurysms after flow diverter treatment. Endovascular approaches that enhance fibrin accumulation could potentially improve aneurysm occlusion rates. Further research is needed to establish the precise role of fibrin in aneurysm occlusion.

Abstract 1069: Novel Approaches Dissecting Human Thrombus Composition

Introduction: Thrombus formation is a key contributor to ischemic stroke and cardiovascular diseases. Variations in thrombus composition involving platelets, fibrin, and leukocytes play a pivotal role in the pathophysiology, impacting clinical outcomes. Understanding its character and the interplay with Neutrophil Extracellular Traps (NETs) is clinically vital due to treatment response and outcome. This study introduces light-sheet microscopy and holotomography to dissect clot composition, aiming to enhance clinical insights into thrombosis. Unraveling these complexities holds promise for targeted interventions and improved patient outcomes. Aims: This study aimed to enhance our understanding of human blood thrombus composition by employing a novel approach using light-sheet microscopy and holotomography. Methods: Human thrombus samples were obtained by mechanical thrombectomy from acute ischemic stroke patients. To access the thrombus structure, the samples were cleared by a tissue-clearing rapid system, and light-sheet microscope imaging was obtained with CitH3, CD45, P-selectin, and fibrin. Holotomography images were obtained from cryosectioned thrombus at 5μm thickness and stained with DAPI and CitH3. Holotomography provided quantitative information on the refractive index of thrombus components. Comparative analysis with traditional imaging methods was performed to assess the advantages of the novel approaches. Results: The results revealed a comprehensive visualization of the spatial arrangement of human thrombus composition through light-sheet microscopy imaging. Holotomography successfully acquired a three-dimensional image of a thrombus section sample. HT images were used to qualitatively distinguish differences in neutrophil RI distribution by NETosis and differences in RI values within the immune cell population. Conclusion: This study demonstrates the efficacy of combining light sheet microscopy and holotomography to comprehensively dissect human thrombus composition. The integration of these advanced imaging techniques provides an understanding of thrombosis, surpassing the limitations of traditional methods.

Traditional Thrombus Composition and Related Endovascular Outcomes: Catching up with the Recent Evidence.

Endovascular thrombectomy is the primary treatment for acute intracranial vessel occlusion and significantly improves recanalization success rate. However, achieving optimal recanalization remains a challenge. The histopathological components of thrombus composition play a crucial role in determining endovascular outcomes. This review aimed to consolidate the recent evidence on the impact of thrombus composition on mechanical properties and endovascular outcomes. The relationship between thrombus composition and mechanical properties was significant, with fibrin and/or platelet-rich thrombi being stiff, tough, elastic, and less deformable; fibrin-rich thrombi were sticky and had higher friction with the vessel wall. Erythrocyte composition was positively associated with successful recanalization, whereas lower platelet composition was associated with specific outcomes, such as the first-pass effect and complete recanalization. The number of thrombectomy device passes was possibly related to erythrocyte, platelet, and fibrin composition, with a smaller number of passes associated with erythrocyte-rich thrombi. Procedural time was consistently related to thrombus composition, with shorter times observed for erythrocyte-rich thrombi. The relationship between thrombus composition and secondary embolism remains inconclusive. Understanding the role of thrombus composition in endovascular outcomes is crucial to optimize stroke treatment. Although evidence suggests a link between thrombus composition and mechanical properties, further research is needed to establish stronger correlations and to reduce study variations. Exploring non-traditional thrombus components such as leukocytes and neutrophil extracellular traps is vital. Thrombus imaging could provide a practical solution for predicting thrombus composition before endovascular procedures. This review highlights the importance of thrombus composition for enhancing endovascular stroke treatment strategies.

316 Acute Ischemic Stroke Presentation Labs and Imaging Can Be Used to Model Thrombus Proteomic Composition

INTRODUCTION: The literature points to a strong relationship between the composition of acute ischemic stroke thrombi and their susceptibility to thrombolytic or endovascular treatment. Composition can be determined by molecular studies of the clot itself, but there is tremendous utility in being able to predict clot composition solely on data available at patient presentation. METHODS: Quantitative proteomes were generated using mass spectrometry of thromboembolic material retrieved by thrombectomy from 59 stroke patients. Of the 2,790 total identified proteins, marker proteins were selected to identify broad groups of thrombus components: RBCs (12 proteins), platelets (9 proteins), histones (23 proteins) and neutrophils (13 proteins). Dimensional reduction of marker proteins was done by principal component (PC) analysis for each group. A broad survey of demographic, lab, and radiographic data was gathered by retrospective chart review. Regression analysis was used to identify the combination of the four variables on chart review that most strongly associated with the PCs for each thrombus component group. RESULTS: After dimensional reduction, a significant amount of the variance in marker protein abundance for each group was represented by the first PC for each group (R2 > 0.94 for all). It was possible to generate linear models representing the PC associated with RBCs (R2 = 0.37, p = 0.02), platelets (R2 = 0.40, p = 0.0004), histones (R2 = 0.52 and p = 0.001), and neutrophils (R2 = 0.81, p = 1E-12) using combinations of four data points at presentation. CONCLUSIONS: This preliminary work suggests that the abundance of clot components may be predicted by modeling patient data available at presentation, which has the potential to drive future choice of therapy. Next steps include refining and validating the models on a prospectively maintained stroke database at our home institution.

Abstract TMP87: Thrombus Age in Ischemic Stroke With Atrial Fibrillation

Background and purpose: Because the biochemical composition of thrombus changes after formation over time, thrombus maturation in the left atrium may affect clot compositions in ischemic stroke with atrial fibrillation (AF). We aimed to investigate the association of the age of retrieved thrombi with clinical features and outcomes after MT for ischemic stroke with AF. Methods: We retrospectively reviewed consecutive patients with ischemic stroke with known AF or AF diagnosed after stroke onset who underwent MT and whose retrieved thrombi were pathologically analyzed. Thrombi were classified as fresh (<1 day) and older (1-5 days) based on the areas (≤20 % or >20 %) of lytic features of granulocytes in the section. Components of thrombi were quantified using immunostaining. Outcomes included first pass effect (FPE, extended Thrombolysis in Cerebral Infarction [eTICI] 2c/3 after first pass) and favorable outcome (3-month modified Rankin Scale score of 0 to 2 or equal to premorbid mRS score). Results: Of 168 patients, 62 patients (37%) had older thrombi. The presence of older thrombi was independently associated with the higher CHADS 2 score (adjusted OR [aOR], 1.46; 95% confidence interval [CI], 1.07-1.99). Older thrombi had the higher proportion of fibrin, platelets, von Willebrand factor, and neutrophil extracellular traps than fresh thrombi. FPE was less frequently achieved in patients with older thrombi than those with fresh thrombi (21% versus 43%; aOR, 0.36; 95% CI, 0.17-0.77). Favorable outcomes were fewer in patients with older thrombi than those with fresh thrombi (40% versus 73%; aOR, 0.37; 95% CI, 0.16-0.85). Conclusions: In patients with ischemic stroke with AF, older thrombi was associated with cardiovascular risk factors and included abundant amounts of components associated with the thrombectomy resistance. Patients with older thrombi had poorer functional outcomes presumably due to concomitant risk factors and worse revascularization outcomes.

ANALYSIS OF RELATIONSHIPS BETWEEN HETEROGENEOUS RADIOMIC FEATURES OF THROMBUS IN ACUTE ISCHEMIC STROKE

Ischemic stroke is one of the most widely recognised cerebral pathologies. Its diagnosis starts with computed tomography (CT). However, a comprehensive understanding of the characteristics of the thrombus is necessary to establish an appropriate and less hazardous treatment. This study focusses on the analysis of thrombus heterogeneity in CT images of patients with acute ischemic stroke (AIS). The radiomic features of the thrombus were used to obtain the voxel distribution in the new feature space. It was then reduced using Principal Component Analysis (PCA) and subjected to visualisation techniques such as t-distributed Stochastic Neighbour Embedding (tSNE) and Uniform Manifold Approximation and Projection for Dimension Reduction (UMAP). By evaluating the morphological structure of the clusters created within patients, it was possible to determine the number of thrombus components. This information could help the physician predict the burden on the patient during thrombectomy, such as the number of attempts required for recanalization.

A Comprehensive Approach to Analyze the Cell Components of Cerebral Blood Clots.

Cerebral thrombosis, a blood clot in a cerebral artery or vein, is the most common type of cerebral infarction. The study of the cell components of cerebral blood clots is important for diagnosis, treatment, and prognosis. However, the current approaches to studying the cell components of the clots are mainly based on in situ staining, which is unsuitable for the comprehensive study of the cell components because cells are tightly wrapped in the clots. Previous studies have successfully isolated a fibrinolytic enzyme (sFE) from Sipunculus nudus, which can degrade the cross-linked fibrin directly, releasing the cell components. This study established a comprehensive method based on the sFE to study the cell components of cerebral thrombus. This protocol includes clot dissolving, cell releasing, cell staining, and routine blood examination. According to this method, the cell components could be studied quantitatively and qualitatively. The representative results of experiments using this method are shown.

Quantitative Susceptibility Mapping as a Biomarker to Assess Middle Cerebral Artery Thrombus Composition in Acute Ischemic Stroke

Objective: To compare the quantitative susceptibility mapping (QSM) susceptibility values and pathology composition with different types of thrombi in the middle cerebral artery (MCA), and assess the value of susceptibility weight imaging in thrombus component diagnosis in stroke. Materials and methods: This study included 15 patients (73.47 ± 10.7 years; 6 males and 9 females) who underwent magnetic resonance imaging before mechanical thrombectomy due to acute middle cerebral artery occlusion between January 2017 and December 2019. All patients had the susceptibility vessel sign (SVS) on SWI (susceptibility weighted imaging), and the thrombus susceptibility was measured by signal processing in nuclear magnetic resonance SPIN software. The retrieved thrombi underwent histopathologic analysis, and the correlation between thrombus susceptibility and the pathologic composition was analyzed by two independent Kolmogorov–Smirnov tests. The location and length of thrombi were evaluated on both SWI and DSA, and the correlation was explored using two independent samples Wilcoxon rank test. The correlations between susceptibility and the infarct core volumes (ADC < 620 mm2/s volume map), hypoperfusion volumes (Tmax > 6 s volume map), 90-day modified Rankin scale (mRS), and the National Institutes of Health Stroke Scale (NIHSS) at admission were analyzed by Spearman’s correlation analysis. Results: Among the 15 retrieved thrombi, the mean thrombus susceptibility of RBC-dominant and fibrin-dominant thrombi were 209.88 ± 11.32 and 155.70 ± 28.20 (ppb), respectively (p = 0.037). The average distance of the proximal end of the thrombi to the midline was 24.67 ± 8.43 mm and 24.62 ± 8.44 mm, as measured by SWI and DSA (digital subtraction angiography), respectively (p < 0.001). The correlation between thrombus susceptibility was weakly negatively correlated with ADC < 620 mm2/s volume map (r = 0.356, p = 0.193) and poorly correlated with Tmax > 6 s volume map (r = 0.252, p = 0.365), 90-day mRS (r = 0.182, p = 0.517), and NIHSS at admission (r = 0.262, p = 0.345). Conclusions: The measurements of the Quantitative susceptibility value of thrombi may help predict the composition of thrombi in patients with acute middle cerebral artery occlusion. QSM provides a more accurate method to evaluate the thrombi.

The mechanistic and structural role of von Willebrand factor in endotoxemia-enhanced deep vein thrombosis in mice

BackgroundAlthough the concept of immunothrombosis has established a link between inflammation and thrombosis, the role of inflammation in the pathogenesis of deep vein thrombosis remains to be fully elucidated. Further, although various constituents of venous thrombi have been identified, their localizations and cellular and molecular interactions are yet to be combined in a single, multiplexed analysis. ObjectivesThe objective of this study was to investigate the role of the von Willebrand factor (VWF) in inflammation-associated venous thrombosis. We also performed a proof-of-concept study of imaging mass cytometry to quantitatively and simultaneously analyze the localizations and interactions of 10 venous thrombus constituents. MethodsWe combined the murine inferior vena cava stenosis model of deep vein thrombosis with the lipopolysaccharide model of endotoxemia. We also performed a proof-of-concept study of imaging mass cytometry to assess the feasibility of this approach in analyzing the structural composition of thrombi. ResultsWe found that lipopolysaccharide-treated mice had significantly higher incidences of venous thrombosis, an effect that was mitigated when VWF was inhibited using inhibitory αVWF antibodies. Our detailed structural analysis also showed that most thrombus components are localized in the white thrombus regardless of endotoxemia. Moreover, although endotoxemia modulated the relative representation and interactions of VWF with other thrombus constituents, the scaffolding network, comprised VWF, fibrin, and neutrophil extracellular traps, remained largely unaffected. ConclusionsWe observe a key role for VWF in the pathogenesis of inflammation-associated venous thrombosis while providing a more comprehensive insight into the molecular interactions that constitute the architecture of venous thrombi.

Histopathological Features of Cancer-Associated Venous Thromboembolism: Presence of Intrathrombus Cancer Cells and Prothrombotic Factors.

Cancer-associated venous thromboembolism (VTE) is a critical complication in patients with cancer. However, the pathological findings of VTE are limited. Here, we investigated the histopathological features of cancer-associated VTE in human autopsy cases. We clinically examined the autopsy cases of VTE with (n=114) and without cancer (n=66) and immunohistochemically analyzed the expression of prothrombotic factors in intrathrombus cancer cells, the thrombus contents of erythrocytes, fibrin, platelets, citrullinated histone H3, and degree of organization. Vascular wall invasion or small cell clusters of cancer cells was observed in thrombi in 27.5% of deep vein thrombosis and 25.9% of pulmonary embolism cases. The majority of the cancer cells in deep vein thrombi appeared to be invading the vessel wall, whereas the majority of pulmonary thrombi had cancer cell clusters, consistent with embolization via blood flow. These cancer cells were immunohistochemically positive for TF (tissue factors) or podoplanin in up to 88% of VTE cases. The frequency of TF-positive monocyte/macrophages in thrombi was higher in cancer-associated VTE than that in VTE without cancer. Citrullinated histone H3 was predominantly observed in the early stages of organizing thrombi. There was no significant difference in thrombus components between VTE with cancer and without cancer groups. Vascular wall invasion or cancer cell clusters in thrombi might influence thrombogenesis of cancer-associated VTE. TF and podoplanin in cancer cells and in monocyte/macrophages may induce coagulation reactions and platelet aggregation. Neutrophil extracellular traps may play a role in the early stages of VTE, regardless of cancer status.

Is Composition of Brain Clot Retrieved by Mechanical Thrombectomy Associated with Stroke Aetiology and Clinical Outcomes in Acute Ischemic Stroke?-A Systematic Review and Meta-Analysis.

Background: Brain clots retrieved following endovascular thrombectomy in acute ischemic stroke patients may offer unique opportunities to characterise stroke aetiology and aid stroke decision-making in select groups of patients. However, the evidence around the putative association of clot morphology with stroke aetiology is limited and remains inconclusive. This study aims to perform a systematic review and meta-analysis to delineate the association of brain clot composition with stroke aetiology and post-reperfusion outcomes in patients receiving endovascular thrombectomy. Methods: The authors conducted a systematic literature review and meta-analysis by extracting data from several research databases (MEDLINE/PubMed, Cochrane, and Google Scholar) published since 2010. We used appropriate key search terms to identify clinical studies concerning stroke thrombus composition, aetiology, and clinical outcomes, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: The authors identified 30 articles reporting on the relationship between stroke thrombus composition or morphology and aetiology, imaging, or clinical outcomes, of which 21 were included in the meta-analysis. The study found that strokes of cardioembolic origin (SMD = 0.388; 95% CI, 0.032–0.745) and cryptogenic origin (SMD = 0.468; 95% CI, 0.172–0.765) had significantly higher fibrin content than strokes of non-cardioembolic origin. Large artery atherosclerosis strokes had significantly lower fibrin content than cardioembolic (SMD = 0.552; 95% CI, 0.099–1.004) or cryptogenic (SMD = 0.455; 95% CI, 0.137–0.774) strokes. Greater red blood cell content was also significantly associated with a thrombolysis in cerebral infarction score of 2b–3 (SMD = 0.450; 95% CI, 0.177–0.722), and a positive hyperdense middle cerebral artery sign (SMD = 0.827; 95% CI, 0.472–1.183). No significant associations were found between red blood cell, platelet, or white blood cell content and aetiology, or between clot composition and bridging thrombolysis. Conclusions: This meta-analysis found that fibrin composition is significantly higher in strokes of cardioembolic and cryptogenic origin, and that red blood cell content is positively associated with the hyperdense middle cerebral artery sign and better reperfusion outcomes. Important advances to stroke clinical workup can be derived from these findings, in which many aspects of stroke workflow remain to be optimised. As data are still limited in terms of the association of various thrombus components with stroke aetiology as well as a standardised method of analysis, further studies are required to validate these findings to guide their use in clinical decision-making.

Thrombus formation during ECMO: Insights from a detailed histological analysis of thrombus composition

ObjectivesIntra‐device thrombosis remains one of the most common complications during extracorporeal membrane oxygenation (ECMO). Despite anticoagulation, approximately 35% of patients develop thrombi in the membrane oxygenator, pump heads, or tubing. The aim of this study was to describe the molecular and cellular features of ECMO thrombi and to study the main drivers of thrombus formation at different sites in the ECMO circuits. Approach and ResultsThrombi (n = 85) were collected immediately after veno‐arterial‐(VA)‐ECMO circuit removal from 25 patients: 23 thrombi from the pump, 25 from the oxygenator, and 37 from the tubing. Quantitative histological analysis was performed for the amount of red blood cells (RBCs), platelets, fibrin, von Willebrand factor (VWF), leukocytes, and citrullinated histone H3 (H3Cit). ECMO thrombi consist of a heterogenous composition with fibrin and VWF being the major thrombus components. A clustering analysis of the four major histological parameters identified two typical thrombus types: RBC‐rich and RBC‐poor/fibrin‐rich thrombi with no significant differences in VWF and platelet content. Thrombus composition was not associated with the thrombus location, except for higher amounts of H3Cit that were found in pump and oxygenator thrombi compared to tubing samples. We observed higher blood leukocyte count and lactate dehydrogenase levels in patients with fibrin‐rich thrombi. ConclusionWe found that thrombus composition is heterogenous, independent of their location, consisting of two types: RBC‐rich and a fibrin‐rich types. We also found that NETs play a minor role. These findings are important to improve current anticoagulation strategies in ECMO.

Composition and Organization of Acute Ischemic Stroke Thrombus: A Wealth of Information for Future Thrombolytic Strategies.

During the last decade, significant progress has been made in understanding thrombus composition and organization in the setting of acute ischemic stroke (AIS). In particular, thrombus organization is now described as highly heterogeneous but with 2 preserved characteristics: the presence of (1) two distinct main types of areas in the core—red blood cell (RBC)-rich and platelet-rich areas in variable proportions in each thrombus—and (2) an external shell surrounding the core composed exclusively of platelet-rich areas. In contrast to RBC-rich areas, platelet-rich areas are highly complex and are mainly responsible for the thrombolysis resistance of these thrombi for the following reasons: the presence of platelet-derived fibrinolysis inhibitors in large amounts, modifications of the fibrin network structure resistant to the tissue plasminogen activator (tPA)-induced fibrinolysis, and the presence of non-fibrin extracellular components, such as von Willebrand factor (vWF) multimers and neutrophil extracellular traps. From these studies, new therapeutic avenues are in development to increase the fibrinolytic efficacy of intravenous (IV) tPA-based therapy or to target non-fibrin thrombus components, such as platelet aggregates, vWF multimers, or the extracellular DNA network.

An in vitro model for Extracellular DNA Traps (ETs)-rich Human Thrombus Analogs

BackgroundExtracellular DNA traps (ETs) have important implications in both thrombosis and thrombolysis. Thus, developing benchtop thrombus analogs that recapitulate clinical ETs is potentially of great value for preclinical development and...

Extent of mural thrombus is not associated with increased 5-year mortality following elective AAA repair.

Mural thrombus in abdominal aortic aneurysm (AAA) has been associated with increased rates of aneurysm growth as well as adverse cardiovascular events. The extent of mural thrombus in thoracoabdominal aortic aneurysms has recently been linked to 1-year mortality following endovascular repair and has been hypothesized as a marker for reduced cardiac reserve. This study investigates whether the extent of mural thrombus in infra-renal AAA is associated with 5-year mortality following elective repair. Retrospective review of all patients undergoing elective infra-renal AAA repair at a single academic medical center between 2007 and 2016 was performed. The following variables at the time of surgery were investigated for association with 5-year mortality: age, sex, ethnicity, insurance status and co-morbidities, repair type, renal insufficiency, end-stage renal disease on dialysis, history of smoking, coronary artery disease, congestive heart failure, diabetes mellitus, hypertension, stroke, chronic obstructive pulmonary disease, body mass index category, AAA diameter, and ratio of aortic thrombus to total aneurysm diameter. Amongst 427 patients undergoing infra-renal AAA repair during the study period, 232 met extensive inclusion criteria. Univariate analysis found mean age (76 vs 72, p < 0.01), age cohort over 72 years (OR = 1.9, p = 0.04), renal insufficiency (OR = 3.1, p < 0.01), ESRD (OR = 6.5, p < 0.01), AAA diameter 6cm or greater (OR = 2.3, p < 0.01), and mean AAA diameter (61.36vs 56.99mm, p < 0.01) all predictive of 5-year mortality. Multivariate analysis revealed renal insufficiency (p < 0.01) and AAA diameter 6cm or greater (p = 0.03) to be significantly associated with 5-year mortality. The extent of mural thrombus was identical between 5-year survivors and non-survivors. The mean inner to outer AAA diameter was 0.65 in the survivor cohort and 0.64 in the mortality cohort. Inner to outer ratio of < 0.5 was identified in 23% of 5-year survivors and 27% of the mortality group. In our experience, the extent of mural thrombus in AAA does not influence long-term survival after elective repair. AAA repair may provide protection against circulating components of mural thrombus which have the potential to promote atherosclerotic-related adverse events. Patients with renal insufficiency and larger AAA have increased risk of mortality 5 years after elective repair.

No Histological Difference between Large Atherosclerotic and Cardiogenic Embolic Thrombus.

Background The continuous development of endovascular treatment technology provides more opportunities for the histological study of thrombus. According to Trial of Org 10 172 in Acute Stroke Treatment (TOAST), clinicians take different strategies in anticoagulant or antiplatelet therapy. There are some patients still suffering from recurrent stroke while they took anticoagulant or antiplatelet drugs regularly for secondary prevention. In view of that, we found that histological analysis of thrombus can provide guidance for secondary prevention. Aim Exploring the histological characteristics differences between large atherosclerotic and cardiogenic embolic thrombosis in order to guide clinical secondary prevention of the two stroke subtypes. Methods A total of 54 patients with acute ischemic stroke were collected from December 2019 to April 2021. Identify stroke subtypes according to TOAST classification. Stain thrombus specimens with hematoxylin-eosin staining, and perform statistical analysis on the components (red blood cells and fibrin/platelets) of thrombus. Results In cardiogenic thrombi, the composition of RBCs was dominant (51.38 ± 18.463%) compared to that of fibrin/platelets (48.62 ± 18.463%). Similarly, among the thrombi of large artery atherosclerotic, RBCs (50.40 ± 20.100%) compared to fibrin/platelets (49.60 ± 20.100%). There was no statistical difference in RBCs or fibrin/platelet composition of both cardiogenic and atherosclerotic thrombi (P = 0.89). Conclusions The histologic composition of thrombi in cardiogenic and atherosclerotic had no statistical difference. These thrombi are all mixed thrombus, which are rich in RBCs, fibrinogen, and platelets. Anticoagulation combined with antiplatelet may be a more effective secondary prevention strategy.

Leukocytes in Cerebral Thrombus Respond to Large-Vessel Occlusion in a Time-Dependent Manner and the Association of NETs With Collateral Flow.

Thrombus components are dynamically influenced by local blood flow and blood immune cells. After a large-vessel occlusion stroke, changes in the cerebral thrombus are unclear. Here we assessed a total of 206 cerebral thrombi from patients with ischemic stroke undergoing endovascular thrombectomy. The thrombi were categorized by time to reperfusion of <4 h (T4), 4–8 h (T4–8), and >8 h (T8). The cellular compositions in thrombus were analyzed, and relevant clinical features were compared. Both white blood cells and neutrophils were increased and then decreased in thrombus with time to reperfusion, which were positively correlated with those in peripheral blood. The neutrophil extracellular trap (NET) content in thrombus was correlated with the degree of neurological impairment of patients. Moreover, with prolonged time to reperfusion, the patients showed a trend of better collateral grade, which was associated with a lower NET content in the thrombus. In conclusion, the present results reveal the relationship between time-related endovascular immune response and clinical symptoms post-stroke from the perspective of thrombus and peripheral blood. The time-related pathological changes of cerebral thrombus may not be the direct cause for the difficulty in thrombolysis and thrombectomy. A low NET content in thrombi indicates excellent collateral flow, which suggests that treatments targeting NETs in thrombi might be beneficial for early neurological protection.

Abstract TP159: The Effect Of Diabetes Mellitus On Thrombus Composition In Patients With Stroke

Introduction: Outcomes of mechanical thrombectomy (MT) are influenced by the composition of thrombi. Amongst the risk factors affecting clot composition, diabetes mellitus (DM) may be associated with more thrombus structural and mechanical alterations resulting in fibrinolysis-resistant thrombi. However, extensive analysis of the composition of thrombi obtained from patients is needed to elucidate this relationship. Hypothesis: Thrombi retrieved from patients with DM may have different compositions compared to that of patients with no history of DM. Methods: MT retrieved-thrombi from patients suffering from large vessel occlusion (LVO) stroke were included. Thrombi sections were stained with Martius Scarlet Blue (MSB) for main thrombus components including red blood cells (RBCs), white blood cells (WBCs), fibrin and platelet. Additionally, immunohistochemistry (IHC) was performed to identify neutrophil extracellular traps (NETs) (anti-citrulinated H3; CitH3; NETs-specific marker) and von Willebrand Factor (vWF) in thrombi. Slides were then scanned and analyzed and the thrombus composition was compared between patients with or without a DM diagnosis at the time of stroke presentation. Results: A total of 140 patients were included of which 35 had a diagnosis of DM at stroke presentation. Baseline characteristics (excluding age), IV-tPA use prior to MT, and MT outcomes (number of device passes and final mTICI score) were similar between DM and non DM patients. The overall average percentage of RBCs, WBCs, fibrin, platelet, NETs (CitH3), and vWF components in thrombi were 47.4%, 3.2%, 27.4%, 21.8%, 25.9% and 17.6%, respectively. Thrombi from patients with DM were not statistically significant different from those of patients with no DM in terms of RBCs (44.3 vs 48.4 p=0.37), WBCs (2.7 vs 3.3 p=0.05), fibrin (29.5 vs 26.7 p=0.37), platelet (23.3 vs 21.3 p=0.57), NETs (25.6 vs 22.3 p=0.54), and vWF (17.5 vs 17.7 p=0.96). Conclusion: DM has no effect on the composition of thrombi as no significant difference was found in thrombi obtained from patients with and without DM.

Abstract TP146: The Effect Of Statins On Thrombus Composition Retrieved By Mechanical Thrombectomy In Acute Ischemic Stroke

Introduction: Ample evidence exists in support of the anti-inflammatory properties of statins which in turn could affect arterial thrombosis. Compositional analysis of thrombi retrieved by MT may provide us with knowledge useful for evaluating the effect of current Statin therapy on thrombus composition. Methods: Consecutive AIS-LVO patients were included. Histopathological evaluation of thrombi retrieved during MT was performed using Martius Scarlet Blue staining (MSB) and immunohistochemistry for von Willebrand Factor (vWF) and anti-citrulinated H3 (CitH3; NETs marker) and the composition of thrombi was determined using image analysis software. Thrombus was considered rich in a given composition if that composition was higher than its overall mean. We reviewed patient’s medication records and cataloged any statin therapy prior to MT. Results: 117 patients were included in this study. The mean density of red blood cells (RBCs), white blood cells (WBCs), platelets (PLT), fibrin (FIB), vWF and NETs (CitH3) in thrombi was 43.4%, 3.7%, 23.6%, 29.3%, 14.3% and 21.1% respectively. Twenty-seven patients were taking Statins at the time of MT. Statins were not associated with pre-thrombectomy IV-tPA, and stroke etiology (p values: &gt;0.05). There was no association between Statins and thrombi composition and type (p values: &gt;0.05 for all thrombus components and type). Additionally, Statins were not associated with MT outcomes including number of device passes and final mTICI score. Conclusion: Pre-stroke Statin therapy was not associated with differences in thrombus composition.