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

Abstract

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.

Association of Procedure Time With Clinical and Procedural Outcome in Patients With Basilar Occlusion Undergoing Embolectomy

“…Second, there were higher rates of atrial fibrillation and cardioembolic origin in the fast and intermediate group, which might result in different fibrin composition. 34 The clot compositions were associated with the PT and the outcomes, 35 although this study lacks the data of clot composition, multivariable regression that adjusted for stroke etiology and atrial fibrillation still showed that longer PT were associated with worse outcomes. It is likely that PT can reflect the information of both the vascular (ICAS, occlusion site) but also the occlusion (stroke etiology and clot composition), and these all together make PT a strong predictor of the favorable outcome.…”

Advancing Stroke Research on Cerebral Thrombi with Omic Technologies

“…Regarding undetermined etiologies, data from histopathological studies highlighted similar features between cryptogenic and cardioembolic clots, in particular, similar proportions of PF [ 18 ]. A recent meta-analysis of 21 studies found that cardioembolic and cryptogenic clots have a high PF content and indicated a positive association between RBC-rich clots and better reperfusion rates [ 32 ]. Accordingly, several studies showed that IVT and EVT are more effective in clots with higher content of RBCs [ 16 , 33 , 34 ].…”

“…Although thrombus immunohistopathology has provided valuable data in stroke research, the wide variability of the findings currently hampers clinical translatability [ 20 , 32 ]. The implementation of more standardized methods and the complementary use of novel biomolecular techniques in future studies—such as omic technologies—may lead to more reliable results that could better guide therapeutic decisions.…”

Sexual dimorphism in peripheral blood cell characteristics linked to recanalization success of endovascular thrombectomy in acute ischemic stroke

“…Fibrin- and thrombocyte-rich clots, which are more common in cardioembolic stroke [ 4 – 6 ], are associated with unsuccessful recanalization because of greater stiffness and adhesion to the vessel wall [ 1 ]. Erythrocyte-rich clots, on the other hand, are more common in atherosclerotic stroke [ 4 , 6 ], and associated with successful recanalization [ 4 , 5 , 7 , 8 ]. AIS etiology is associated with sex, where women are less likely to have atherosclerotic stroke [ 9 , 10 ].…”