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.

College of Medicine Central Michigan University Saginaw Michigan USA

Department of Imaging Methods University of Ostrava Ostrava Czech Republic

Department of Mechanical Engineering University of Michigan Ann Arbor Michigan USA

Department of Neurology University of California Los Angeles Los Angeles California USA

Department of Neuroradiology Technical University Munich Munich Germany

Department of Neurosurgery Mayo Clinic Rochester Minnesota USA

Department of Neurosurgery University of Michigan Ann Arbor Michigan USA

Department of Radiology Mayo Clinic Rochester Minnesota USA

Department of Radiology University of Michigan Ann Arbor Michigan USA

Department of Surgical Pathology Complejo Hospitalario Universitario de Albacete Albacete Spain

Interventional Neuroradiology Unit Department of Neurology Complejo Hospitalario Universitario de Albacete Albacete Spain

University of Michigan Medical School Ann Arbor Michigan USA

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