Background Initial studies investigating correlations between stroke etiology and clot composition are conflicting and do not account for clot size as determined by area. Radiological studies have shown that cardioembolic strokes are associated with shorter clot lengths and lower clot burden than non-cardioembolic clots.
Objective To report the relationship between stroke etiology, extracted clot area, and histological composition at each procedural pass.
Methods As part of the multi-institutional RESTORE Registry, the Martius Scarlett Blue stained histological composition and extracted clot area of 612 per-pass clots retrieved from 441 patients during mechanical thrombectomy procedures were quantified. Correlations with clinical and procedural details were investigated.
Results Clot composition varied significantly with procedural passes; clots retrieved in earlier passes had higher red blood cell content (H4=11.644, p=0.020) and larger extracted clot area (H4=10.730, p=0.030). Later passes were associated with significantly higher fibrin (H4=12.935, p=0.012) and platelets/other (H4=15.977, p=0.003) content and smaller extracted clot area. Large artery atherosclerotic (LAA) clots were significantly larger in the extracted clot area and more red blood cell-rich than other etiologies in passes 1–3. Cardioembolic and cryptogenic clots had similar histological composition and extracted clot area across all procedural passes.
Conclusion LAA clots are larger and associated with a large red blood cell-rich extracted clot area, suggesting soft thrombus material. Cardioembolic clots are smaller in the extracted clot area, consistent in composition and area across passes, and have higher fibrin and platelets/other content than LAA clots, making them stiffer clots. The per-pass histological composition and extracted clot area of cryptogenic clots are similar to those of cardioembolic clots, suggesting similar formation mechanisms.
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Contributors SF, IS, TT, AR, JT, and KD, were involved in all stages of the manuscript from concept design to drafting the manuscript. All other authors participated in various aspects of the project and reviewed and edited the manuscript prior to submission. AP, RM, MG, WB, DFK, and GT were involved in the study design and data interpretation. RR, OMM, DJ, AO, AD, and SMG performed the experiments and analysis described, including measurement of the extracted clot area, histological staining, and quantification of the cases and statistical analysis. DD, ANo, EC, PR, KJ, ND, GM, AO, SP, PB, JA, ANa, AV, and KP, collected clot samples and extracted corresponding clinical data for each patient at each of their respective participating hospitals.
Funding This work was supported by the European Regional Development Fund and Science Foundation Ireland grant number (13/RC/2073) and by the National Institutes of Health grant number (R01 NS105853).
Competing interests The authors declare competing interests (funding, employment or personal financial interests) in relation to the work described herein. KD received research funding support from Science Foundation Ireland that is co-funded by Cerenovus.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.
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