Thrombus components in cardioembolic and atherothrombotic strokes

A Study on the Efficacy of Thrombectomy in Patients with Atherosclerotic and Cardioembolic Basilar Artery Occlusion

Background  Studies on basilar artery occlusion are relatively few compared with those of anterior circulation stroke. The aim of the present study was to compare the efficacy of endovascular therapy (EVT) in patients with basilar artery occlusion classified as large artery atherosclerosis (LAA) and cardioembolism (CE), and to analyze the independent risk factors affecting the prognosis of EVT. Methods  A total of 123 people were assigned to the LAA and CE groups (97 to the LAA and 26 to the CE). The primary outcome was a modified Rankin Scale (mRS) score of 2 or lower at 90 days. The primary safety outcome was mortality at 90 days. Secondary safety endpoints included the rates of symptomatic intracranial hemorrhage and reinfarction. Multiple logistic regression was used to screen out independent risk factors for EVT prognosis of the LAA and CE groups. Results  In the analysis, the patients with LAA stroke had better collateral circulation (American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology [SIR] score of 2-4; 61.9 vs. 19.2%, p  = 0.000), and higher angioplasty rate (32.0 vs. 3.8%, p  = 0.002). The proportions of patients with a 90-day mRS score of 0 to 2 and 90-day mortality were not found to be statistically significant between the two groups. Multivariate logistic regression analysis indicated that age, SIR, white blood cell, blood glucose, and modified thrombolysis in cerebral infarction were independent risk factors for the poor prognosis of EVT in the LAA group. Conclusion  Although there were differences in clinical characteristics and imaging features between LAA and CE, there was no evidence of a significant difference in prognosis after EVT. In addition, the National Institutes of Health Stroke Scale score was not among the independent risk factors affecting the prognosis of the LAA group.

Relationship between thrombus composition and prognosis in patients with acute ischemic stroke undergoing mechanical thrombectomy

BACKGROUND

Mechanical thrombectomy has emerged as the primary endovascular treatment for acute ischemic stroke. Numerous studies have investigated the relationship between thrombus composition and factors such as pharmacological thrombolysis, stroke etiology, mechanical thrombectomy, and radiological imaging. However, limited research has explored the association between thrombus composition and clinical outcomes.

METHODS

This retrospective analysis examined the histopathological examination of thrombi retrieved from 50 patients with acute ischemic stroke between May 2020 and May 2023. The composition of the retrieved thrombi was assessed using HE staining to quantify the proportions of red blood cells, white blood cells, platelets, and fibrin. Based on the predominant composition of the thrombus, the patients were divided into two groups: erythrocyte-rich and fibrin-rich. Demographics, clinical characteristics, and clinical outcomes assessed by the National Institutes of Health Stroke Scale (NIHSS) score and modified Rankin Scale (mRS) scores were collected retrospectively.

RESULT

Of the 50 patients, 23 were classified in the erythrocyte-rich group, and 27 were classified in the fibrin-rich group. There were no significant differences between the two groups in terms of age, sex, stroke subtype, history of hypertension and diabetes, thrombus location, NIHSS scores, mRS scores on admission, the time interval from symptom onset to hospitalization and reperfusion, or the rate of successful reperfusion. However, erythrocyte-rich thrombi were associated with a shorter time interval from puncture to reperfusion. No significant differences were found in the red blood cell fraction and fibrin/platelet fraction between large artery atherosclerosis and cardioembolism. At the 90-day follow-up, patients with erythrocyte-rich thrombi exhibited lower NIHSS scores and more favorable functional outcomes (mRS scores of 0-2) compared to those with fibrin-rich thrombi.

CONCLUSION

Erythrocyte-rich thrombi were linked to shorter time intervals from puncture to reperfusion and favorable clinical outcomes in patients with acute ischemic stroke. The composition of the thrombus may influence the thrombectomy strategy for endovascular therapy.

Age and composition of the thrombus retrieved by mechanical thrombectomy from patients with acute ischemic stroke are associated with revascularization and clinical outcomes

INTRODUCTION

Understanding the composition of stroke thrombi retrieved by mechanical thrombectomy is essential to clarify the pathogenesis of stroke. However, it is difficult to evaluate thrombus composition precisely and objectively. Immunohistochemical staining was used to evaluate thrombus composition and age.

MATERIALS AND METHODS

Consecutive thrombi (n = 108) retrieved from patients who underwent mechanical thrombectomy for acute large-vessel ischemic stroke were retrospectively analyzed. Lytic features of granulocytes and CD163 were estimated as indicators of the age of the cardioembolic (CE) thrombus.

RESULTS

The stroke subtypes were as follows: CE, 74 cases; large artery atherosclerosis, 11; undetermined etiology, 12; and other determined etiology, 11. There were no statistical differences in thrombi composition according to stroke subtypes. The fibrin area was positively correlated with the red blood cell (RBC) and platelet areas. The following analysis was performed using CE only. Regarding age, the thrombus was judged as fresh in 30.0 % and older in 70.0 % based on the lytic features. The RBC areas of older thrombi were smaller than those of fresh thrombi. The puncture-to-reperfusion time of older thrombi was longer than that of fresh thrombi. Platelet-rich thrombi were associated with a greater number of maneuvers, a smaller prevalence of TICI 3, and unfavorable functional outcomes compared to platelet-poor thrombi. The number of CD163 positive cells in thrombi with anticoagulants was higher than in those without anticoagulants.

CONCLUSION

Thrombus composition correlated with revascularization and clinical outcomes. The composition of an acute ischemic thrombus may reflect the pathophysiology of stroke and influence treatment efficacy.

[Susceptibility vessel sign in subacute stroke patients with large vessel occlusion]

OBJECTIVE

To investigate the presentation of susceptibility vessel sign (SVS) in subacute stroke patients with large vessel occlusion.

METHODS

We collected consecutive stroke patients who were admitted to Peking University First Hospital from December 2017 to August 2019 retrospectively. Those who had intracranial large vessel occlusion and received sensitivity weighted imaging (SWI) within 3 to 14 days after stroke onset were included in our analysis. The diagnosis of large vessel occlusion was based on magnetic resonance angiography (MRA), CT angiography (CTA) or digital subtraction angiography (DSA). The demographic information, clinical characteristics and imaging results were obtained from medical record. The occurrence rates of SVS sign were compared between stroke patients with cardioembolism (CE) and large artery atherosclerosis (LAA). In the sensitivity analysis, we performed a subgroup analysis in those patients who received SWI within 7 to 14 days after stroke onset. We also compared the occurrence rate of SVS sign between the patients with and without atrial fibrillation.

RESULTS

A total of 51 patients, 19 females and 32 males, with an average age of (63.04±11.23) years were analyzed in this study. Compared with LAA group, the patients in CE group were older and more likely to have an atrial fibrillation (P < 0.05). There were no significant differences between the CE group and LAA group in gender, hypertension, diabetes, coronary heart disease, hyperlipidemia, smoking, or National Institute of Health stroke scale(NIHSS) score at admission. SVS sign was found in 30 patients. Of whom, 3 were in CE group and 27 in LAA group. The occurrence rate of SVS sign was higher in the LAA group than in the CE group significantly (65.9% vs. 30.0%, P=0.039). The subgroup analysis showed that, in the patients who received SWI examination within 7 to 14 days after stroke onset, the differences between the two groups were still statistically significant (0 vs. 72.7%, P=0.006). Another sensitivity analysis showed that, the rate of SVS in the patients with atrial fibrillation was significantly lower than those patients without atrial fibrillation (25% vs. 65.1%, P=0.043).

CONCLUSION

In subacute stroke patients, the occurrence rate of SVS sign in CE group was lower than that of LAA group. The significance of SVS sign in the differentiation of stroke subtype needs further validation.

Thrombus Histology as It Relates to Mechanical Thrombectomy: A Meta-Analysis and Systematic Review

BACKGROUND

Appropriate thrombus-device interaction is critical for recanalization. Histology can serve as a proxy for mechanical properties, and thus inform technique selection.

OBJECTIVE

To investigate the value of histologic characterization, we conducted a systematic review and meta-analysis on the relationship between thrombus histology and recanalization, technique, etiology, procedural efficiency, and imaging findings.

METHODS

In this meta-analysis, we identified studies published between March 2010 and March 2020 reporting findings related to the histologic composition of thrombi in large vessel occlusion stroke. Studies with at least 10 patients who underwent mechanical thrombectomy using stent retriever or aspiration were considered. Only studies in which retrieved thrombi were histologically processed were included. Patient-level data were requested when data could not be directly extracted. The primary outcome assessed was the relationship between thrombus histology and angiographic outcome.

RESULTS

A total of 22 studies encompassing 1623 patients met inclusion criteria. Clots associated with good angiographic outcome had higher red blood cell (RBC) content (mean difference [MD] 9.60%, 95% CI 3.85-15.34, P = .008). Thrombi retrieved by aspiration had less fibrin (MD -11.39, 95% CI -22.50 to -0.27, P = .046) than stent-retrieved thrombi. Fibrin/platelet-rich clots were associated with longer procedure times (MD 13.20, 95% CI 1.30-25.10, P = .037). Hyperdense artery sign was associated with higher RBC content (MD 14.17%, 95% CI 3.07-25.27, P = .027). No relationship was found between composition and etiology.

CONCLUSION

RBC-rich thrombi were associated with better recanalization outcomes and shorter procedure times, suggesting that preinterventional compositional characterization may yield important prognostic and therapeutic guidance.

Studying Stroke Thrombus Composition After Thrombectomy: What Can We Learn?

The composition of ischemic stroke thrombi has gained an increasing amount of interest in recent years. The implementation of endovascular procedures in standard stroke care has granted researchers the unique opportunity to examine patient thrombus material. Increasing evidence indicates that stroke thrombi are complex and heterogenous, consisting of various biochemical (eg, fibrin, von Willebrand Factor, and neutrophil extracellular traps) and cellular (eg, red blood cells, platelets, leukocytes, and bacteria) components. This complex composition may explain therapeutic limitations and also offer novel insights in several aspects of stroke management. Better understanding of thrombus characteristics could, therefore, potentially lead to improvements in the management of patients with stroke. In this review, we provide a comprehensive overview of the lessons learned by examining stroke thrombus composition after endovascular thrombectomy and its potential relevance for thrombectomy success rates, thrombolysis, clinical outcomes, stroke etiology, and radiological imaging.

Development and reliability of the histological THROMBEX-classification rule for thrombotic emboli of acute ischemic stroke patients

Background

Thrombus histology has become a potential diagnostic tool for the etiology assessment of patients with ischemic stroke caused by embolic proximal vessel occlusion. We validated a classification rule that differentiates between cardiac and arteriosclerotic emboli in individual stroke patients. We aim to describe in detail the development of this classification rule and disclose its reliability.

Methods

The classification rule is based on the hypothesis that cardiac emboli arise out of separation thrombi and arteriosclerotic emboli result from agglutinative thrombi. 125 emboli recovered by thrombectomy from stroke patients and 11 thrombi serving as references for cardiac (n = 5) and arteriosclerotic emboli (n = 6) were Hematoxylin and eosin, Elastica-van Gieson and CD61 stained and rated independently by two histopathologists blinded to the presumed etiology by several pre-defined criteria. Intra- and interobserver reliabilities of all criteria were determined. Out of the different criteria, three criteria with the most satisfactory reliability values were selected to compose the classification rule that was finally adjusted to the reference thrombi. Reliabilities of the classification rule were calculated by using the emboli of stroke patients.

Results

The classification rule reached intraobserver reliabilities for the two raters of 92.9% and 68.2%, respectively. Interobserver reliability was 69.9%.

Conclusions

A new classification rule for emboli obtained from thrombectomy was established. Within the limitations of histological investigations, it is reliable and able to distinguish between cardioembolic and arteriosclerotic emboli.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42466-021-00149-6.

Relation of Pre-Stroke Aspirin Use With Cerebral Infarct Volume and Functional Outcomes

Objective

We investigated (1) the associations of pre‐stroke aspirin use with thrombus burden, infarct volume, hemorrhagic transformation, early neurological deterioration (END), and functional outcome, and (2) whether stroke subtypes modify these associations in first‐ever ischemic stroke.

Methods

This multicenter magnetic resonance imaging (MRI)‐based study included 5,700 consecutive patients with acute first‐ever ischemic stroke, who did not undergo intravenous thrombolysis or endovascular thrombectomy, from May 2011 through February 2014. Propensity score‐based augmented inverse probability weighting was performed to estimate adjusted effects of pre‐stroke aspirin use.

Results

The mean age was 67 years (41% women), and 15.9% (n = 907) were taking aspirin before stroke. Pre‐stroke aspirin use (vs nonuse) was significantly related to a reduced infarct volume (by 30%), particularly in large artery atherosclerosis stroke (by 45%). In cardioembolic stroke, pre‐stroke aspirin use was associated with a ~50% lower incidence of END (adjusted difference = −5.4%, 95% confidence interval [CI] = −8.9 to −1.9). Thus, pre‐stroke aspirin use was associated with ~30% higher likelihood of favorable outcome (3‐month modified Rankin Scale score < 3), particularly in large artery atherosclerosis stroke and cardioembolic stroke (adjusted difference = 7.2%, 95% CI = 1.8 to 12.5 and adjusted difference = 6.4%, 95% CI = 1.7 to 11.1, respectively). Pre‐stroke aspirin use (vs nonuse) was associated with 85% less frequent cerebral thrombus‐related susceptibility vessel sign (SVS) in large artery atherosclerosis stroke (adjusted difference = −1.4%, 95% CI = −2.1 to −0.8, p < 0.001) and was associated with ~40% lower SVS volumes, particularly in cardioembolic stroke (adjusted difference = −0.16 cm³, 95% CI = −0.29 to −0.02, p = 0.03). Moreover, pre‐stroke aspirin use was not significantly associated with hemorrhagic transformation (adjusted difference = −1.1%, p = 0.09).

Interpretation

Pre‐stroke aspirin use associates with improved functional independence in patients with first‐ever ischemic large arterial stroke by reducing infarct volume and/or END, likely by decreasing thrombus burden, without increased risk of hemorrhagic transformation. ANN NEUROL 2021;90:763–776

[Current opportunities for secondary prevention of atherothrombotic stroke]

The article is devoted to an urgent medical and social problem - secondary prevention of atherothrombotic stroke and contains current evidence on the use of combined antiplatelet and anticoagulant therapy. In the COMPASS study, the dual-pathway thrombosis inhibition scheme using rivaroxaban in combination with acetylsalicylic acid (ASA) compared with ASA monotherapy demonstrated in patients with established atherosclerotic diseases of the circulatory system, a decrease in the total risk of stroke, death from cardiovascular causes and myocardial infarction by 24%; reduced risk of recurrent stroke by 67%. The incidence of repeated ischemic stroke (IS) in the combination therapy group was 1.1% per year, in the ASA group - 3.4% per year. The total incidence of adverse outcomes included in the combined indicator «net clinical benefit» in the rivaroxaban group in combination with ASA was 20% lower than in the ASA group and confirms the advantages of combination therapy in the prevention of recurrent noncardioembolic IS.

Thrombus Structural Composition in Cardiovascular Disease

Thrombosis is a major complication of cardiovascular disease, leading to myocardial infarction, acute ischemic stroke, or venous thromboembolism. Thrombosis occurs when a thrombus forms inside blood vessels disrupting blood flow. Developments in thrombectomy to remove thrombi from vessels have provided new opportunities to study thrombus composition which may help to understand mechanisms of disease and underpin improvements in treatments. We aimed to review thrombus compositions, roles of components in thrombus formation and stability, and methods to investigate thrombi. Also, we summarize studies on thrombus structure obtained from cardiovascular patients and animal models. Thrombi are composed of fibrin, red blood cells, platelets, leukocytes, and neutrophil extracellular traps. These components have been analyzed by several techniques, including scanning electron microscopy, laser scanning confocal microscopy, histochemistry, and immunohistochemistry; however, each technique has advantages and limitations. Thrombi are heterogenous in composition, but overall, thrombi obtained from myocardial infarction are composed of mainly fibrin and other components, including platelets, red blood cells, leukocytes, and cholesterol crystals. Thrombi from patients with acute ischemic stroke are characterized by red blood cell- and platelet-rich regions. Thrombi from patients with venous thromboembolism contain mainly red blood cells and fibrin with some platelets and leukocytes. Thrombus composition from patients with myocardial infarction is influenced by ischemic time. Animal thrombosis models are crucial to gain further mechanistic information about thrombosis and thrombus structure, with thrombi being similar in composition compared with those from patients. Further studies on thrombus composition and function are key to improve treatment and clinical outcome of thrombosis.

First approach to distinguish between cardiac and arteriosclerotic emboli of individual stroke patients applying the histological THROMBEX-classification rule

Endovascular treatment of strokes caused by large vessel occlusion enables the histopathological investigation of the retrieved embolus, possibly providing a novel opportunity to contribute to the diagnostic workup of etiology and to define secondary prevention measures in strokes with uncertain genesis. We aimed to develop a classification rule based on pathophysiological considerations and adjustment to reference thrombi for distinction between cardiac and arteriosclerotic emboli and to validate this classification rule on a patient cohort. From 125 patients with stroke due to large vessel occlusion and thrombectomy, 82 patients with known etiology (55 cardioembolic and 27 arterioembolic strokes) were included. The corresponding emboli were histologically evaluated by two raters blinded to the etiology of stroke by means of a novel classification rule. Presumed etiology and classification results were compared. Agreement concerning cardiac emboli was 72.2% (95% CI: 58.4–83.5) for rater I and 78.2% (95% CI: 65.0–88.2) for rater II. Agreement concerning arteriosclerotic emboli was 70.4% (95% CI: 49.8–86.3) for rater I and 74.1% (95% CI: 53.7–88.9) for rater II. Overall agreement reached 71.6% (95% CI: 60.5–81.1) for rater I and 76.8% (95% CI: 66.2–85.4) for rater II. Within the limits of generally restricted accuracy of histological evaluations, the classification rule differentiates between cardiac and arteriosclerotic emboli of acute ischemic stroke patients. Further improvement is needed to provide valuable complementary data for stroke etiology workup.

Thrombus Composition and Efficacy of Thrombolysis and Thrombectomy in Acute Ischemic Stroke

Thrombi retrieved from patients with acute ischemic stroke are highly heterogeneous. Recent data suggest that thrombus composition may impact on mechanical thrombectomy, the number of recanalization manoeuvres, resistance to retrieval, and on thrombolytic potential. Our aim was to summarize evidence describing the impact of thrombus composition on efficacy of mechanical thrombectomy and thrombolysis in patients with acute ischemic stroke. The scoping review methodology guided by the Joanna Briggs Institute, an adaption of the Arksey and O'Malley, was followed. Comprehensive searches were conducted in MEDLINE, EMBASE, SCOPUS, and Web of Science. Articles were classified into 4 key themes: (1) composition of stroke thrombi, (2) thrombus composition and mechanical thrombectomy, (3) thrombus composition and thrombolytic therapy, and (4) novel imaging and endovascular approaches. Our search identified 698 articles published from 1987 to June 2020. Additional articles were extracted from reference lists of the selected articles. Overall, 95 topic-specific articles identified for inclusion published in 40 different journals were included. Reports showed that thrombus composition in stroke was highly heterogeneous, containing fibrin, platelets, red blood cells, VWF (von Willebrand Factor), and neutrophil extracellular traps. Thrombi could roughly be divided into fibrin- and red blood cell-rich clots. Fibrin-rich clots were associated with increased recanalization manoeuvres, longer procedure time, and less favorable clinical outcomes compared with red blood cell-rich clots. Advances in detection or treatment of thrombi that take into account clot heterogeneity may be able to improve future endovascular and thrombolytic treatment of stroke.

Immunohistological Analysis of Neutrophils and Neutrophil Extracellular Traps in Human Thrombemboli Causing Acute Ischemic Stroke

Ischemic stroke caused by thromboembolic occlusion of large cerebral arteries, such as the internal carotid (ICA) and/or the middle cerebral artery (MCA), is treated by mechanical thrombectomy (MT). MT allows salvage of the vessel-occluding thrombemboli, which most frequently originate from the left atrium or the left ventricle of the heart or from sites of plaque rupture within large arteries above the heart. Clot composition may influence the efficacy of (intravenous) thrombolysis and MT, respectively. We analyzed 37 human thrombemboli obtained from acute ischemic stroke patients during MT with special emphasis on histological staining of neutrophils and neutrophil extracellular traps (NETs). We found neutrophils as the main cellular component of cerebral thrombemboli but encountered considerable morphological heterogeneity. Neutrophils accumulated in the border region of fibrin-rich structures indicating possible interaction of neutrophils with distinct structural thrombembolus components. Web-like NETs were found in 35 of 37 thrombemboli in varying amounts. NETs were almost exclusively found within fibrin-rich areas. Importantly, stroke etiology, age and present oral anticoagulation was associated with morphological patterns and the amount of neutrophils. Correlation of histological data and imaging data revealed that relative Hounsfield units of cerebral thrombemboli positively correlated with the amount of red blood cells. In summary, our results demonstrate that neutrophils and NETs are substantial constituents of cerebral thrombemboli and contribute to their structural complexity.

Pathophysiologic and Therapeutic Perspectives Based on Thrombus Histology in Stroke

Recent advances in endovascular thrombectomy have enabled the histopathologic analysis of fresh thrombi in patients with acute stroke. Histologic analysis has shown that the thrombus composition is very heterogeneous between patients. However, the distribution pattern of each thrombus component often differs between patients with cardiac thrombi and those with arterial thrombi, and the efficacy of endovascular thrombectomy is different according to the thrombus composition. Furthermore, the thrombus age is related to the efficacy of reperfusion therapy. Recent studies have shown that neutrophils and neutrophil extracellular traps contribute to thrombus formation and resistance to reperfusion therapy. Histologic features of thrombi in patients with stroke may provide some clues to stroke etiology, which is helpful for determining the strategy of stroke prevention. Research on thrombus may also be helpful for improving reperfusion therapy, including the development of new thrombolytic agents.

Impact of Mechanical Thrombectomy Device on Thrombus Histology in Acute Embolic Stroke

BACKGROUND

Although many studies have evaluated the retrieved thrombus to assess the cause of stroke after mechanical thrombectomy for acute large vessel occlusion, the results remain controversial. We investigated the hypothesis that histology of the retrieved thrombus is enhanced by mechanical thrombectomy devices.

METHODS

Thrombi were collected from consecutive patients who had undergone endovascular mechanical recanalization for large intracranial vessel occlusion. The mechanical thrombectomy device used was either an aspiration catheter or a stent retriever. The hematoxylin and eosin-stained specimens were quantitatively analyzed with respect to the relative fractions of the main constituents (erythrocytes and fibrin). Clinical and radiologic findings were also evaluated.

RESULTS

Of 65 patients, an aspiration catheter was used in 27, and a stent retriever was used in 38. The presence of a preoperative susceptibility vessel sign on magnetic resonance imaging was not correlated with the percentage of erythrocytes. Thrombus cross-sectional area was larger in the aspiration group than in the stent group (P < 0.01). Conversely, the percentage of the fibrin component was higher in the stent group (P < 0.001). Preoperative intravenous administration of recombinant tissue plasminogen activator reduced thrombus cross-sectional area with a trend of increased percentage of fibrin and reduced percentage of erythrocyte in the stent group.

CONCLUSIONS

Histologic differences in retrieved thrombi are enhanced by mechanical thrombectomy devices. Stent retrievers may crush the thrombus, which may have a synergistic effect with recombinant tissue plasminogen activator. Histology of the retrieved thrombi might be different from histology of the original thrombi.

Correlation of imaging and histopathology of thrombi in acute ischemic stroke with etiology and outcome

Mechanical thrombectomy has become the stand of care for patients with large vessel occlusions, yet major improvements in thrombectomy speed, efficacy, and completeness can still be achieved. High rates of clot fragmentation and failure to remove the clot resulting in poor neurological outcomes suggest that in order to further advance the field of stroke intervention we must turn our attention towards understanding the science of clot. Accurately identifying the composition of the occlusive clot prior to intervention could significantly influence the success of the revascularization strategy used to treat them. Numerous features of thromboemboli could be studied and characterized, including quantitative histomorphometry and diagnostic imaging characteristics. Each of these features might logically predict superior thrombectomy outcomes with one device or another. This article aims to review the current literature on histopathological composition of acute ischemic stroke clots, with a particular focus on the correlation between clot composition and diagnostic imaging, stroke etiology and revascularization outcomes.

Comparison between blood coagulability in the intra-atrial and peripheral regions during the acute phase after rapid atrial pacing

The changes in intra-atrial blood coagulability of acute phase after development of atrial fibrillation (AF) have not been elucidated in human. In the present study, blood coagulability were examined in the intra-atrial and peripheral regions during the acute phase after development of rapid atrial pacing (RAP) in experimentally created model dog similar to AF, using Total Thrombus-formation Analysis System (T-TAS) that is capable of comprehensively evaluating thrombogenicity in the bloodstream in the microvascular channel. According to the results, both the coagulating function-evaluating time to +10 kPa (T10) and occlusion time (OT) of the AR chip (chip for thrombus analysis mixed with coagulation and platelet) were significantly shortened in the atrial blood as early as 30 min after pacing (T10, 150.5 ± 40.5 s; OT, 212.4 ± 44.3 s) compared to the pre-pacing levels (T10, 194.5 ± 47.5 s; OT, 259.9 ± 49.5 s) (P<0.05). The OT of PL chip (chip for platelet thrombus analysis) was significantly shortened 30 min after pacing (231.8 ± 57.6 s), compared to the pre-pacing level (289.5 ± 96.0 s) (P<0.05). Meanwhile, none of T10 and OT of AR and PL chips showed any significant changes in the peripheral blood. The study demonstrated increase of blood coagulability 30 min after development of RAP. While no significant changes were observed in the peripheral blood in the present study, the outcome suggested that the anti-thrombus treatments are better to be started early after AF even if coagulability of the peripheral blood shows no change.

Efficacy of Thrombus Density on Noninvasive Computed Tomography Neuroimaging for Predicting Thrombus Pathology and Patient Outcome after Mechanical Thrombectomy in Acute Ischemic Stroke

Background and Purpose:

The aim of this study was to investigate the efficacy of thrombus density on noninvasive computed tomography (CT) neuroimaging for predicting thrombus pathology and patient outcome after mechanical thrombectomy in acute ischemic stroke.

Materials and Methods:

This retrospective chart and imaging review included patients that were treated by mechanical thrombectomy at Siriraj Hospital according to the American Heart Association/American Stroke Association guidelines for the early management of patients with acute ischemic stroke from March 2010 to February 2015 study period. Preintervention noncontrast CT (NCCT), CT angiography (CTA), and/or contrast-enhanced CT (CECT) images were interpreted using CT densitometry. Pathology results were classified as white, red, or mixed thrombi. The result of treatment was evaluated by the modified Rankin Scale at 90 days after treatment.

Results:

From 97 included patients – 97 NCCT images, 48 CTA images, 48 CECT images, and 54 pathologic results of cerebral thrombi were included in the final analysis. Mean clot Hounsfield unit values on NCCT, CTA, and CECT were significantly different between red and white thrombus (P = 0.001 on NCCT, P = 0.03 on CTA, and P = 0.001 on CECT), and between red and mixed thrombus (P = 0.043 on NCCT and P = 0.002 on CTA). However, no significant difference was observed between white thrombus and mixed thrombus (P = 0.09 on NCCT, P = 1.00 on CTA, and P = 0.054 on CECT). There was no significant correlation between type of cerebral thrombus or clot density and the result of treatment.

Conclusion:

Thrombus density on CT was found to be a significant predictor of thrombus pathology; however, no significant association was observed between thrombus type or clot density and patient outcome after mechanical thrombectomy.

Impact of Smoking on Clinical Outcome and Recanalization After Intravenous Thrombolysis for Stroke

Background and Purpose—

The impact of smoking on prognosis after stroke is controversial. We aimed to assess the relationship between smoking status and stroke outcome after intravenous thrombolysis in a large cohort study by adjusting for potential confounders and incorporating recanalization rates.

Methods—

In a prospective observational multicenter study, we analyzed baseline and outcome data of consecutive patients with acute ischemic stroke treated with intravenous thrombolysis. Using uni- and multivariable modeling, we assessed whether smoking was associated with favorable outcome (modified Rankin Scale score of 0–1) and mortality. In addition, we also measured the occurrence of symptomatic intracranial hemorrhage and recanalization of middle cerebral artery. Patients reporting active cigarette use were classified as smokers.

Results—

Of 1865 patients, 19.8% were smokers (n=369). They were younger (mean 63.5 versus 71.3 years), less often women (56% versus 72.1%), and suffered less often from hypertension (61.3% versus 70.1%) and atrial fibrillation (22.7% versus 35.6%) when compared with nonsmokers. Favorable outcome and 3-month mortality were in favor of smokers in unadjusted analyses (45.8% versus 39.5% and 9.3% versus 15.8%, respectively), whereas symptomatic intracranial hemorrhage was comparable in both cohorts. Smoking was not associated with clinical outcome and mortality after adjusting for confounders (odds ratio, 1.20; 95% confidence interval, 0.91–1.61; P =0.197 and odds ratio, 1.08; 95% confidence interval, 0.68–1.71; P =0.755, respectively). However, smoking still independently predicted recanalization of middle cerebral artery in multivariable analyses (odds ratio, 2.68; 95% confidence interval, 1.11–6.43; P =0.028).

Conclusions—

Our study suggests that good outcome in smokers is mainly related to differences in baseline characteristics and not to biological effects of smoking. The higher recanalization rates in smokers, however, call for further studies.

Thromboembolism and Mortality in the Tasmanian Atrial Fibrillation Study

BACKGROUND

Although utilization of anticoagulation in patients with atrial fibrillation (AF) has increased in recent years, contemporary data regarding thromboembolism and mortality incidence rates are limited outside of clinical trials. This study aimed to investigate the impact of the direct oral anticoagulants (DOACs) on the clinical outcomes of patients with AF included in the Tasmanian Atrial Fibrillation Study.

METHODS

The medical records of all patients with a primary or secondary diagnosis of AF who presented to public hospitals in Tasmania, Australia, between 2011 and 2015, were retrospectively reviewed. We investigated overall thromboembolic events (TEs), ischemic stroke/transient ischemic attack (IS/TIA), and mortality incidence rates in patients admitted to the Royal Hobart Hospital, the main teaching hospital in the state. We compared outcomes in 2 time periods: prior to the availability of DOACs (pre-DOAC; 2011 to mid-2013) and following their general availability after government subsidization (post-DOAC; mid-2013 to 2015).

RESULTS

Of the 2390 patients with AF admitted during the overall study period, 942 patients newly prescribed an antithrombotic medication (465 and 477 from the pre-DOAC and post-DOAC time periods, respectively) were followed. We observed a significant decrease in the incidence rates of overall TE (3.2 vs 1.7 per 100 patient-years [PY]; P < .001) and IS/TIA (2.1 vs 1.3 per 100 PY; P = .022) in the post-DOAC compared to the pre-DOAC period. All-cause mortality was significantly lower in the post-DOAC period (2.9 vs 2.2 per 100 PY, P = .028). Increasing age, prior stroke, and admission in the pre-DOAC era were all risk factors for TE, IS/TIA, and mortality in this study population. The risk of IS/TIA was more than doubled (hazard ratio: 2.54; 95% confidence interval: 1.17-5.52) in current smokers compared to ex- and nonsmokers.

CONCLUSION

Thromboembolic event and all-cause mortality rates were lower following the widespread availability of DOACs in this population.

Prediction of the Multisegment Clot Sign on Dynamic CT Angiography of Cardioembolic Stroke

BACKGROUND AND PURPOSE

The multisegment clot sign has been observed at the site of large-artery occlusion in patients with acute ischemic stroke. This study aimed to assess its occurrence rate and relationship with stroke etiologies in patients with acute intracranial large-artery occlusion.

MATERIALS AND METHODS

We included consecutive patients with acute ischemic stroke who had acute intracranial large-artery occlusion and underwent perfusion CT within 8 hours after stroke onset. The multisegment clot sign was assessed on dynamic CT angiography derived from perfusion CT. The stroke etiologies were defined by the international Trial of Org 10172 in Acute Stroke Treatment criteria. Poisson regression analyses and diagnostic testing were used to investigate the relationship between the multisegment clot sign and stroke etiologies.

RESULTS

Finally, 194 patients with intracranial large-artery occlusion were enrolled. According to the Trial of Org 10172 in Acute Stroke Treatment criteria, 110 (56.7%) patients were diagnosed with cardioembolism; 43 (22.2%), with large-artery atherosclerosis; and 41 (21.1%), with undetermined etiology. The multisegment clot sign was found in 74 (38%) patients. Poisson regression analysis showed that the presence of the multisegment clot sign was significantly higher in patients with cardioembolism than in those with large-artery atherosclerosis (52.7% versus 9.3%; prevalence ratio, 1.53; 95% confidence interval, 1.03-2.90; P = .037). For determined etiologies, the sensitivity, specificity, and positive and negative predictive values of the multisegment clot sign for predicting cardioembolism were 52.7%, 90.7%, 93.5%, and 42.9%, respectively.

CONCLUSIONS

The presence of the multisegment clot sign on dynamic CTA specifically indicates intracranial large-artery occlusion caused by an embolism from a cardiac source, which may be useful for acute management and secondary prevention of stroke.

Predictive Value of Computed Tomography Angiography-Determined Occlusion Type in Stent Retriever Thrombectomy

BACKGROUND AND PURPOSE

We investigated whether occlusion type identified with computed tomography angiography (CTA-determined occlusion type) could predict endovascular treatment success using stent retriever (SR) thrombectomy.

METHODS

Consecutive patients with stroke who underwent CTA and then endovascular treatment for intracranial large artery occlusion were retrospectively reviewed. CTA-determined occlusion type was classified into truncal-type occlusion or branching-site occlusion and compared with digital subtraction angiography-determined occlusion type during endovascular treatment. Three rapidly- and readily-assessable pre-procedural findings (CTA-determined occlusion type, atrial fibrillation, and hyperdense artery sign), which may infer occlusion pathomechanism (embolic versus nonembolic) before endovascular treatment, were evaluated for association with SR success along with stroke risk factors and laboratory results. In addition, the predictive power of the 3 pre-procedural findings for SR success was compared with receiver operating characteristic curve analyses.

RESULTS

A total of 238 patients (mean age, 70.0 years; male patients, 52.9%) were included in this study. CTA-determined occlusion type corresponded adequately with digital subtraction angiography-determined occlusion type (P=0.453). Atrial fibrillation (odds ratio, 2.66; 95% confidence interval, 1.25-5.66) and CTA-determined branching-site occlusion (odds ratio, 8.20; confidence interval, 3.45-19.5) were independent predictors for SR success. For predicting SR success, the area under the receiver operating characteristic curve value for CTA-determined branching-site occlusion (0.695) was significantly greater than atrial fibrillation (0.594; P=0.038) and hyperdense artery sign (0.603; P=0.023).

CONCLUSIONS

CTA-determined branching-site occlusion was significantly associated with SR success. Furthermore, among the 3 rapidly- and readily-assessable pre-procedural findings, CTA-determined branching-site occlusion had the greatest predictive power for SR success.

Comparison of multimodal intra-arterial treatment versus intravenous thrombolysis for hypertensive patients with severe large vessel cerebral infarction

Since intravenous thrombolysis (IVT) is often associated with poor outcomes in hypertensive patients with severe acute cerebral infarction (ACI) due to occlusions of the internal carotid, basilar, or proximal middle cerebral artery, we evaluated whether multimodal intra-arterial treatment (IAT) might improve functional outcomes in this patient population. We retrospectively reviewed the charts of eligible patients who underwent multimodal IAT including intra-arterial thrombolysis, mechanical thrombectomy, balloon and/or stent angioplasty (IAT group) or IVT alone (IVT group). Outcomes included the revascularization rate 24 hours postprocedure, the frequency of survival at 7, 90, and 180 days postonset, and a measure of functional outcomes using the modified Rankin Scale (mRS). The IAT group included 62 patients and the IVT group included 31 patients. Multimodal IAT increased the revascularization rate at 24 hours (p<0.001) and the frequency of survival and functional independence (mRS ≤2) at 7 days (p<0.001 and p=0.018, respectively), 90 days (both p<0.001), and 180 days (both p<0.001). Independent predictors of longer survival were treatment with multimodal IAT (HR 0.1; 95% CI 0.0 to 0.4; p<0.001) and revascularization (HR 0.1; 95% CI 0.0 to 0.4; p<0.001), whereas a longer duration from onset to treatment was a risk factor for death (HR 1.4; 95% CI 1.2 to 1.8; p<0.001). There was no significant between-group difference for symptomatic hemorrhagic transformation. This study found that for patients with severe hypertensive ACI with large vessel occlusions, multimodal IAT improved the outcomes, including early revascularization, survival, and functional outcome.

Correlation of imaging and histopathology of thrombi in acute ischemic stroke with etiology and outcome: a systematic review

BACKGROUND AND PURPOSE

Studying the imaging and histopathologic characteristics of thrombi in ischemic stroke could provide insights into stroke etiology and ideal treatment strategies. We conducted a systematic review of imaging and histologic characteristics of thrombi in acute ischemic stroke.

MATERIALS AND METHODS

We identified all studies published between January 2005 and December 2015 that reported findings related to histologic and/or imaging characteristics of thrombi in acute ischemic stroke secondary to large vessel occlusion. The five outcomes examined in this study were (1) association between histologic composition of thrombi and stroke etiology; (2) association between histologic composition of thrombi and angiographic outcomes; (3) association between thrombi imaging and histologic characteristics; (4) association between thrombi imaging characteristics and angiographic outcomes; and (5) association between imaging characteristics of thrombi and stroke etiology. A meta-analysis was performed using a random effects model.

RESULTS

There was no significant difference in the proportion of red blood cell (RBC)-rich thrombi between cardioembolic and large artery atherosclerosis etiologies (OR 1.62, 95% CI 0.1 to 28.0, p=0.63). Patients with a hyperdense artery sign had a higher odds of having RBC-rich thrombi than those without a hyperdense artery sign (OR 9.0, 95% CI 2.6 to 31.2, p<0.01). Patients with a good angiographic outcome had a mean thrombus Hounsfield unit (HU) of 55.1±3.1 compared with a mean HU of 48.4±1.9 for patients with a poor angiographic outcome (mean standard difference 6.5, 95% CI 2.7 to 10.2, p<0.001). There was no association between imaging characteristics and stroke etiology (OR 1.13, 95% CI 0.32 to 4.00, p=0.85).

CONCLUSIONS

The hyperdense artery sign is associated with RBC-rich thrombi and improved recanalization rates. However, there was no association between the histopathological characteristics of thrombi and stroke etiology and angiographic outcomes.

Analyses of thrombi in acute ischemic stroke: A consensus statement on current knowledge and future directions

Limited data exist on clot composition and detailed characteristics of arterial thrombi associated with large vessel occlusion in acute ischemic stroke. Advances in endovascular thrombectomy and related imaging modalities have created a unique opportunity to analyze thrombi removed from cerebral arteries. Insights into thrombus composition, etiology, physical properties and neurovascular interactions may lead to future advancements in acute ischemic stroke treatment and improved clinical outcomes. Advances in imaging techniques may enhance clot characterization and inform therapeutic decision-making prior to treatment and reveal stroke etiology to guide secondary prevention. Current imaging techniques can provide some information about thrombi, but there remains much to evaluate about relationships that may exist among thrombus composition, occlusion characteristics and treatment outcomes. Improved pathophysiological characterization of clot types, their properties and how these properties change over time, together with clinical correlates from ongoing studies, may facilitate revascularization with thrombolysis and thrombectomy. Interdisciplinary approaches covering clinical, engineering and scientific aspects of thrombus research will be key to advancing the understanding of thrombi and improving acute ischemic stroke therapy. This consensus statement integrates recent research on clots and thrombi retrieved from cerebral arteries and provides a rationale for further analyses, including current opportunities and limitations.

Stroke etiologic subtype may influence the rate of hyperdense middle cerebral artery sign disappearance after intravenous thrombolysis

Disappearance of hyperdense middle cerebral artery sign (HMCAS) on non-contrast brain computed tomography (CT) scan is a reliable sign of arterial recanalization after intravenous (IV) thrombolysis for ischemic stroke. We aimed to assess whether stroke etiologic subtype may influence the rate of HMCAS disappearance and the clinical outcome after IV thrombolysis. We conducted a retrospective analysis of data prospectively collected from 1031 consecutive stroke patients treated with IV thrombolysis. Outcome measures were HMCAS disappearance on follow-up CT scan within 22-36 h of IV thrombolysis, neurologic improvement (NIH Stroke Scale [NIHSS] ≤4 points from baseline or NIHSS score of 0) at 7 days, and modified rankin scale (mRS) ≤1 at 3 months. Of 256 patients with HMCAS on admission CT scan, 125 had a cardioembolic stroke, 67 a stroke due to large-artery atherosclerosis (LAA), 58 a stroke of undetermined etiology, and six a stroke secondary to carotid artery dissection. HMCAS disappearance occurred in 145 (56.6 %) patients, neurologic improvement in 122 (55.0 %) patients, and mRS ≤1 in 64 (32.8 %) patients. Compared with cardioembolic stroke patients, patients with stroke due to LAA had lower odds ratios (OR) for HMCAS disappearance (OR 0.29, 95 % CI 0.15-0.58, p < 0.001), neurologic improvement (OR 0.42, 95 % CI 0.22-0.82, p = 0.011), and mRS ≤1 (OR 0.18, 95 % CI 0.06-0.52, p = 0.002). No significant differences in outcome measures were found between cardioembolic strokes and strokes of undetermined etiology. This study suggests that stroke due to LAA is associated with lower rates of HMCAS disappearance, neurologic improvement, and mRS ≤1 after IV thrombolysis, compared with cardioembolic stroke.

Computed Tomography-Based Thrombus Imaging for the Prediction of Recanalization after Reperfusion Therapy in Stroke

The prediction of successful recanalization following thrombolytic or endovascular treatment may be helpful to determine the strategy of recanalization treatment in acute stroke. Thrombus can be detected using noncontrast computed tomography (CT) as a hyperdense artery sign or blooming artifact on a T2^*-weighted gradient-recalled image. The detection of thrombus using CT depends on slice thickness. Thrombus burden can be determined in terms of the length, volume, and clot burden score. The thrombus size can be quantitatively measured on thin-section CT or CT angiography/magnetic resonance angiography. The determination of thrombus size may be predictive of successful recanalization/non-recanalization after intravenous thrombolysis and endovascular treatment. However, cut-offs of thrombus size for predicting recanalization/non-recanalization are different among studies, due to different methods of measurements. Thus, a standardized method to measure the thrombus is necessary for thrombus imaging to be useful and reliable in clinical practice. Software-based measurements may provide a reliable and accurate assessment. The measurement should be easy and rapid to be more widely used in practice, which could be achieved by improvement of the user interface. In addition to prediction of recanalization, sequential measurements of thrombus volume before and after the treatment may also be useful to determine the efficacy of new thrombolytic drugs. This manuscript reviews the diagnosis of thrombus, prediction of recanalization using thrombus imaging, and practical considerations for the measurement of thrombus burden and density on CT.

Fibrinogen consumption is related to intracranial clot burden in acute ischemic stroke: a retrospective hyperdense artery study

Background

Understanding the underlying mechanism of thrombus formation and its components is critical for effective prevention and treatment of ischemic stroke. The generation of thrombotic clots requires conversion of soluble fibrinogen to an insoluble fibrin network. Quantitative features of intracranial clots causing acute ischemic stroke can be studied on non-contrast enhanced CT (NECT). Here, we evaluated on-admission fibrinogen and clot burden in relation to stroke severity, final infarct volume and in-hospital mortality.

Methods

We included 132 consecutive patients with ischemic stroke and presence of hyperdense artery sign admitted within 6 h from symptom onset. Radiological parameters including clot area (corresponding to clot burden) and final infarct volume were manually determined on NECT. National Institute of Health Stroke Scale (NIHSS) was used to quantify disease severity and short-term outcome.

Results

Median patient age was 77, 58 % were women, and 63 % had an occlusion of the proximal middle cerebral artery segment. Thrombolysis was performed in 60 % and thrombectomy in 44 %. We identified several independent associations. Higher fibrinogen levels on admission were associated with smaller clot burden (p = 0.033) and lower NIHSS on admission (p = 0.022). Patients with lower fibrinogen had a higher clot burden (p = 0.028) and greater final infarct volume (p = 0.003). Higher fibrinogen was associated with a lower risk of in-hospital death or NIHSS score >15 if discharged alive (p = 0.028).

Conclusions

Our study suggests that intracranial clot burden in acute ischemic stroke is associated with fibrinogen consumption, and shows a complex relationship with disease severity, infarct size and in-hospital survival.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1006-6) contains supplementary material, which is available to authorized users.

Smoking-Thrombolysis Relationship Depends on Ischemic Stroke Subtype

BACKGROUND AND PURPOSE

The relationship between smoking and the outcome in patients received thrombolysis is undetermined. The outcome could be influenced by different stroke subtypes. This study aimed to explore whether smoking had any impact on the outcome in patients with stroke of different subtypes who received intravenous thrombolysis.

METHODS

All patients who received intravenous thrombolysis within 4.5 hours after symptom onset from the Thrombolysis Implementation and Monitor of Acute Ischemic Stroke in China (TIMS-China) database were eligible to be entered into this analysis. Smokers were considered if they smoked at least 1 cigarette/d for >6 months before stroke. Ischemic stroke subtype was classified by using the Trial of Org 10172 in Acute Stroke Treatment criteria. Outcome measurements included post-intravenous thrombolysis symptomatic intracranial hemorrhage within 7 days, mortality, and functional independence at 90 days. The relationship between smoking and thrombolysis was analyzed by using univariate and multivariate logistic regression models.

RESULTS

Of 1118 patients enrolled, we identified 454 smokers and 664 nonsmokers. After stratifying for ischemic stroke subtypes, multivariate analysis revealed a significant relationship between smoking and functional independence in patients with noncardioembolism stroke subtypes (large artery atherosclerosis: odds ratio [OR], 1.452; 95% confidence interval [CI], 1.053-2.264; small artery occlusion: OR, 4.275; 95% CI, 1.098-16.649; other: OR, 3.120; 95% CI, 1.162-8.373). Furthermore, smoking was specially related to lower rates of symptomatic intracranial hemorrhage (OR, 0.316; 95% CI, 0.120-0.832) and mortality (OR, 0.272; 95% CI, 0.128-0.577) in patients with large artery atherosclerosis subtype.

CONCLUSIONS

In patients treated with intravenous thrombolysis, smoking could be related to a better chance of functional independence if their subtype of stroke was noncardioembolic, and a lower risk of symptomatic intracranial hemorrhage and mortality in those with large artery atherosclerosis.

Histologic Analysis of Retrieved Clots in Acute Ischemic Stroke: Correlation with Stroke Etiology and Gradient-Echo MRI

BACKGROUND AND PURPOSE

It is unclear whether clot composition analysis is helpful to predict a stroke mechanism in acute large vessel occlusion. In addition, the relationship between early vessel signs on imaging studies and clot compositions has been poorly understood. The purpose of this study was to elucidate the relationship between clot composition and stroke etiology following mechanical thrombectomy and to investigate the effect of varied clot compositions on gradient-echo MR imaging of clots.

MATERIALS AND METHODS

Histopathologic analysis of retrieved clots from 37 patients with acute MCA occlusion was performed. Patients underwent gradient-echo imaging before endovascular therapy. Retrieved clots underwent semiquantitative proportion analysis to quantify red blood cells, fibrin, platelets, and white blood cells by area. Correlations between clot compositions and stroke subtypes and susceptibility vessel signs on gradient-echo imaging were assessed.

RESULTS

Stroke etiology was classified as cardioembolism in 22 patients (59.4%), large-artery atherosclerosis in 8 (21.6%), and undetermined in 7 (18.9%). The clots from cardioembolism had a significantly higher proportion of red blood cells (37.8% versus 16.9%, P = .031) and a lower proportion of fibrin (32.3% versus 48.5%, P = .044) compared with those from large-artery atherosclerosis. The proportion of red blood cells was significantly higher in clots with a susceptibility vessel sign than in those without it (48.0% versus 1.9%, P < .001), whereas the proportions of fibrin (26.4% versus 57.0%, P < .001) and platelets (22.6% versus 36.9%, P = .011) were significantly higher in clots without a susceptibility vessel sign than those with it.

CONCLUSIONS

The histologic composition of clots retrieved from cerebral arteries in patients with acute stroke differs between those with cardioembolism and large-artery atherosclerosis. In addition, a susceptibility vessel sign on gradient-echo imaging is strongly associated with a high proportion of red blood cells and a low proportion of fibrin and platelets in retrieved clots.

Antiplatelet therapy as a modulator of stroke aetiology: a meta-analysis

AIMS

Antiplatelet therapy reduces the incidence of ischaemic stroke. Platelet-mediated thrombosis contributes variably to the major subtypes of stroke as defined by the TOAST criteria: large artery atherosclerosis (LAA), cardioembolic (CE) and small vessel occlusion (SVO). The effect of antiplatelet therapy on the incidence of each subtype is unknown and is the subject of this meta-analysis.

METHODS

Electronic databases were searched for articles comparing the effect of antiplatelet therapy on the incidence of stroke according to aetiological subtype. Studies containing subjects prescribed anticoagulant therapy or solely investigating subjects with atrial fibrillation were excluded. Pooled odds ratios (ORs) were calculated using a fixed effects model.

RESULTS

Nine studies were included (n = 5739). In patients who had an ischaemic stroke, pre-event antiplatelet therapy was associated with significantly decreased incidence of LAA (OR 0.88, 95% CI 0.79, 0.99; P = 0.026), increased incidence of CE (OR 1.23, 95% CI 1.08, 1.41; P = 0.002) and no effect on SVO (OR 0.99, 95% CI 0.88, 1.11; P = 0.806). Concordant non-significant trends were observed in primary prevention populations (n = 751): LAA (OR 0.81, 95% CI 0.57, 1.15; P = 0.240), CE (OR 1.29, 95% CI 0.89, 1.87; P = 0.179) and SVO (OR 0.99, 95% CI 0.73, 1.36; P = 0.970). Subgroup analysis of aspirin monotherapy (n = 3786) demonstrated a significant reduction in LAA (OR 0.87, 95% CI 0.76, 1.00; P = 0.046), but non-significant effects on the incidence of CE (OR 1.17, 95% CI 0.99, 1.39; P = 0.068) and SVO (OR 1.04, 95% CI 0.91, 1.20; P = 0.570). Probability of publication bias was low (P > 0.05).

CONCLUSIONS

Antiplatelet therapy preferentially reduces the incidence of LAA stroke compared with CE and SVO subtypes.

Unfavorable Outcome of Thrombolysis in Chinese Patients with Cardioembolic Stroke: a Prospective Cohort Study

BACKGROUND

Thrombolysis with alteplase is an effective and safe treatment for acute ischemic stroke (AIS). It is controversial whether the outcome of thrombolysis in cardioembolic stroke is different from that of other stroke subtypes. This study compares the outcomes at 3 months postthrombolysis in Chinese patients with AIS secondary to cardioembolism (CE) to the outcomes of those with large-artery atherosclerosis (LAA).

METHODS

Using the Thrombolysis Implementation and Monitoring of Acute Ischemic Stroke in China (TIMS-China) cohort, we prospectively followed 827 patients treated within 4.5 h of onset symptoms with alteplase as an intravenous thrombolytic agent. CE and LAA were defined according to TOAST criteria. We compared symptomatic intracerebral hemorrhage (SICH), mortality, and functional outcome at 3 months using multivariables logistic regression analysis.

RESULTS

In this cohort, 221 (19.6%) had CE and 606 (53.7%) had LAA. Approximately 2/3 of patients with CE had atrial fibrillation. Symptoms at onset were more severe in patients with CE than in those with LAA (NIHSS, 15.0 vs. 11.0; P < 0.0001); increased rate of SICH (5.9% vs. 0.8%; P < 0.0001); higher mortality (18.6% vs. 10.3%; P = 0.0015); and reduced functional independence (43.6% vs. 55.9%; P = 0.0018) at 3-month follow-up. After adjustment for baseline variables, the clinical outcome of patients with CE was worse than that of patients with LAA (OR, 0.62; 95% CI, 0.39 to 0.97, P = 0.0378).

CONCLUSIONS

Patients with cardioembolic stroke had more SICH after thrombolysis, and worse clinical outcome at 3-month follow-up compared with those with LAA. This emphasizes the importance of preventing cardioembolism.

The PlA1/A2 polymorphism of glycoprotein IIIa as a risk factor for stroke: a systematic review and meta-analysis

BACKGROUND

The PlA1/A2 polymorphism of glycoprotein IIIa (GPIIIa) has been reported to be associated with risk of stroke in some studies, although other studies suggest no such association. This meta-analysis and systematic review was conducted to investigate the hypothesis that carriage of the PlA2 allele is a risk factor for stroke.

METHODS

Electronic databases (MEDLINE and EMBASE) were searched for all articles evaluating carriage of the PlA2 allele and the incidence of stroke. Pooled odds ratios (ORs) were calculated using fixed-effect and random-effect models.

FINDINGS

A total of 35 articles were eligible for inclusion, of which 25 studies were suitable for statistical analysis. For carriage of the PlA2 allele, OR 1.12 (n = 11,873; 95% CI = 1.03-1.22; p = 0.011) was observed for the incidence of stroke in adults, with subgroup analyses identifying the association driven by stroke of an ischaemic (n = 10,494; OR = 1.15, 95% CI = 1.05-1.27; p = 0.003) but not haemorrhagic aetiology (n = 2,470; OR = 0.90, 95% CI = 0.71-1.14; p = 0.398). This association with ischaemic stroke was strongest in individuals homozygous for the PlA2 allele compared to those homozygous for wild-type PlA1 (n = 5,906; OR = 1.74, 95% CI = 1.34-2.26; p<0.001). Subgroup analysis of ischaemic stroke subtypes revealed an increased association with stroke of cardioembolic (n = 1,271; OR 1.56, 95% CI 1.14-2.12; p = 0.005) and large vessel (n = 1,394; OR = 1.76, 95% CI 1.34-2.31; p<0.001) aetiology, but not those of small vessel origin (n = 1,356; OR = 0.99, 95% CI 0.74-1.33; p = 0.950). Egger's regression test suggested a low probability of publication bias for all analyses (p>0.05).

CONCLUSIONS

The totality of published data supports the hypothesis that carriage of the PlA2 polymorphism of GPIIIa is a risk factor for ischaemic strokes, and specifically those of cardioembolic and large vessel origin.

Thrombus composition in acute ischemic stroke: a histopathological study of thrombus extracted by endovascular retrieval

BACKGROUND AND PURPOSE

The composition of occlusive thrombus in acute ischemic stroke may affect treatment success. Neuroimaging characteristics may correlate with thrombus composition. In this study we aimed to investigate the relationship between the hyperdense artery sign (HAS) on imaging and thrombus composition.

MATERIALS AND METHODS

Acute ischemic stroke patients who underwent endovascular thrombus retrieval from 2010-2012 were prospectively recruited. One blinded pathologist prepared the histology sections of retrieved thrombi whereby staining with haematoxylin and eosin and CD34 immunostain were performed. Histology sections were categorised into 4 phases of thrombus formation: red blood cell (RBC) dominant, RBC proportion equal to fibrin, fibrin dominant and organised fibrin. Computed tomography (CT) brain scans were assessed for HAS. Fisher's exact test was performed to identify an association between HAS and thrombus composition.

RESULTS

Forty patients were included. The mean age was 65.6±12.9 years and 67.5% were male. Atrial fibrillation was detected in 19 (47.5%) patients, diabetes mellitus in 6 (15.0%), hypercholesterolaemia in 11 (27.5%), hypertension in 20 (50.0%) and previous stroke or transient ischemic attack in 8 (20.0%) patients. Of the retrieved thrombi, 11 (27.5%) were RBC dominant, 11 (27.5%) RBC proportion was equal to fibrin, 7 (17.5%) fibrin dominant and 11 (27.5%) organised fibrin pathology. HAS was present in 29 (72.5%) patients and was significantly associated with thrombus early phase pathology (P<0.05).

CONCLUSION

HAS was significantly associated with early phase thrombus composition. This may enable the prediction of thrombus composition and allow for targeted selection of therapeutic modality.