Abstract DP305: Impact of Multidimensional Histological Clot Composition on the Selection of First Line Technique and Angiographic Outcomes During Mechanical Thrombectomy: A Comprehensive Systematic Review and Meta-Analysis

Background: Histological clot composition has emerged as a potential determinant of mechanical thrombectomy (MT) efficacy, influencing both angiographic and procedural outcomes. However, the relationship between specific clot constituents and the success of first-line techniques and reperfusion remains incompletely understood. Methods: The search strategy, extracted elements, and analysis plan were pre-specified and registered with PROSPERO (CRD420251110596). Pooled mean differences in red blood cell (RBC) and fibrin/platelet (F/P) content under random-effects models were analyzed for angiographic recanalization and procedural efficiency comparing non-first-pass effect (non-FPE) vs. FPE based on the Thrombolysis in Cerebral Infarction (TICI) scale. Additional analyses examined RBC content in clots retrieved via aspiration versus stent retriever (SR)/combined technique, and procedure time differences between RBC-rich and F/P-rich clots. For studies reporting medians and interquartile ranges, Wan’s method was used to estimate means and standard deviations. Results: Fifty studies were included, either reporting on clot composition or length. Compared to clots with TICI <2b, those achieving TICI 2b–3 had significantly higher RBC content (MD −12.0%, 95% CI −19.2 to −4.8, p=0.001) and lower F/P content (MD +8.9%, 95% CI 0.1 to 17.7, p=0.048). RBC-rich clots showed a non-significant trend toward FPE (MD −6.7%, 95% CI −14.3 to 0.9, p=0.084). F/P content was higher in non-FPE cases (MD +9.7%, 95% CI −0.2 to 19.5, p=0.054). Fibrin-rich or F/P-rich clots were associated with longer procedure times compared to RBC-rich clots (MD +13 min, 95% CI 2 to 25, p=0.04). RBC content was significantly higher in clots retrieved by aspiration compared to SR/combined techniques (MD +11.5%, 95% CI 1.7 to 21.4, p=0.04). Lower RBC and higher F/P content were linked to increased distal embolization. Longer clot length correlated with poorer revascularization outcomes and increased distal embolism (Table) . Conclusions: Most studies adopt a one-dimensional approach to clot analysis, often neglecting the interplay between clot parameters, which may confound results. Our findings reinforce clot composition as a critical factor in MT success and highlight the need for individualized thrombectomy strategies informed by clot biology. Development of real-time, in-situ tools to assess clot features during MT could significantly enhance procedural outcomes.