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Original research
Clot composition and recanalization outcomes in mechanical thrombectomy
  1. Raul G Nogueira1,
  2. Agostinho Pinheiro2,
  3. Waleed Brinjikji3,
  4. Mehdi Abbasi3,
  5. Alhamza R Al-Bayati2,
  6. Mahmoud H Mohammaden4,
  7. Lorena Souza Viana5,
  8. Felipe Ferreira5,
  9. Hend Abdelhamid5,
  10. Nirav R Bhatt1,
  11. Peter Kvamme6,
  12. Kennith F Layton7,
  13. Josser E Delgado Almandoz8,
  14. Ricardo A Hanel9,
  15. Vitor Mendes Pereira10,
  16. Mohammed A Almekhlafi11,
  17. Albert J Yoo12,
  18. Babak S Jahromi13,
  19. Matthew J Gounis14,
  20. Biraj Patel15,16,
  21. Jorge L Arturo Larco17,
  22. Sean Fitzgerald3,
  23. Oana Madalina Mereuta3,18,
  24. Karen Doyle19,
  25. Luis E Savastano17,
  26. Harry J Cloft3,
  27. Ike C Thacker7,
  28. Yasha Kayan8,
  29. Alexander Copelan20,
  30. Amin Aghaebrahim21,
  31. Eric Sauvageau22,
  32. Andrew M Demchuk23,24,
  33. Parita Bhuva25,
  34. Jazba Soomro12,
  35. Pouya Nazari13,26,
  36. Donald Robert Cantrell27,
  37. Ajit S Puri28,
  38. John Entwistle16,
  39. Eric C Polley3,
  40. Michael R Frankel4,29,
  41. David F Kallmes3,
  42. Diogo C Haussen30
  1. 1 UPMC Stroke Institute, Pittsburgh, Pennsylvania, USA
  2. 2 Neurology, UPMC Stroke Institute, Pittsburgh, Pennsylvania, USA
  3. 3 Radiology, Mayo Clinic, Rochester, Minnesota, USA
  4. 4 Department of Neurology, Emory University Atlanta, Atlanta, Georgia, USA
  5. 5 Neurology, Emory University, Atlanta, Georgia, USA
  6. 6 Radiology, University of Tennessee Medical Center, Knoxville, Tennessee, USA
  7. 7 NeuroInterventional Radiology, Baylor University Medical Center, Dallas, Texas, USA
  8. 8 Interventional Neuroradiology, Abbot Northwestern Hospital, 55435, Minnesota, USA
  9. 9 Neurosurgery, Baptist Medical Center Jacksonville, Jacksonville, Florida, USA
  10. 10 Division of Neuroradiology, Department of Medical Imaging and Division of Neurosurgery, Department of Surgery, University Health Network - Toronto Western Hospital, Toronto, Ontario, Canada
  11. 11 Clinical Neurosciences, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada
  12. 12 Neurointervention, Texas Stroke Institute, Plano, Texas, USA
  13. 13 Neurosurgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
  14. 14 New England Center for Stroke Research, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
  15. 15 Radiology, Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA
  16. 16 Radiology, Neurosurgery, Carilion Clinic, Roanoke, Virginia, USA
  17. 17 Neurosurgery, Mayo Clinic, Rochester, Minnesota, USA
  18. 18 CÚRAM–SFI Research Centre for Medical Devices and Physiology Department, National University of Ireland Galway, Galway, Ireland
  19. 19 Physiology, CURAM, National University of Ireland Galway, Galway, Ireland
  20. 20 NeuroInterventional Radiology, Abbott Northwestern Hospital, Minneapolis, Minnesota, USA
  21. 21 Lyerly Neurosurgery, Baptist Health System, Jacksonville, Florida, USA
  22. 22 Lyerly Neurosurgery, Baptist Neurological Institute, Jacksonville, Florida, USA
  23. 23 Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
  24. 24 University of Calgary, Calgary, Alberta, Canada
  25. 25 Neuroendovascular Surgery, Texas Stroke Institute, Plano, Texas, USA
  26. 26 Neurosurgery and Radiology, Northwestern University, Chicago, Illinois, USA
  27. 27 Radiology, Northwestern University, Chicago, Illinois, USA
  28. 28 Radiology, University of Massachusetts, Worcester, Massachusetts, USA
  29. 29 Marcus Stroke and Neuroscience Center, Grady Memorial Hospital, Atlanta, Georgia, USA
  30. 30 Neurology and Radiology, Emory University School of Medicine, Atlanta, Georgia, USA
  1. Correspondence to Dr Raul G Nogueira, UPMC Stroke Institute, Pittsburgh, Pennsylvania 15213, USA; raul.g.nogueira{at}


Background Mechanical thrombectomy (MT) has become standard for large vessel occlusions, but rates of complete recanalization are suboptimal. Previous reports correlated radiographic signs with clot composition and a better response to specific techniques. Therefore, understanding clot composition may allow improved outcomes.

Methods Clinical, imaging, and clot data from patients enrolled in the STRIP Registry from September 2016 to September 2020 were analyzed. Samples were fixed in 10% phosphate-buffered formalin and stained with hematoxylin-eosin and Martius Scarlett Blue. Percent composition, richness, and gross appearance were evaluated. Outcome measures included the rate of first-pass effect (FPE, modified Thrombolysis in Cerebral Infarction 2c/3) and the number of passes.

Results A total of 1430 patients of mean±SD age 68.4±13.5 years (median (IQR) baseline National Institutes of Health Stroke Scale score 17.2 (10.5–23), IV-tPA use 36%, stent-retrievers (SR) 27%, contact aspiration (CA) 27%, combined SR+CA 43%) were included. The median (IQR) number of passes was 1 (1–2). FPE was achieved in 39.3% of the cases. There was no association between percent histological composition or clot richness and FPE in the overall population. However, the combined technique resulted in lower FPE rates for red blood cell (RBC)-rich (P<0.0001), platelet-rich (P=0.003), and mixed (P<0.0001) clots. Fibrin-rich and platelet-rich clots required a higher number of passes than RBC-rich and mixed clots (median 2 and 1.5 vs 1, respectively; P=0.02). CA showed a trend towards a higher number of passes with fibrin-rich clots (2 vs 1; P=0.12). By gross appearance, mixed/heterogeneous clots had lower FPE rates than red and white clots.

Conclusions Despite the lack of correlation between clot histology and FPE, our study adds to the growing evidence supporting the notion that clot composition influences recanalization treatment strategy outcomes.

  • Stroke
  • Thrombectomy
  • Device

Data availability statement

Data are available upon reasonable request.

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Data availability statement

Data are available upon reasonable request.

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  • X @agostinhocp, @Mahmoudneuro, @lorena_neuro, @nirav_r_bhatt, @VitorMendesPer1, @AlmekhlafiMa, @PouyaNazari5, @AjitSPuri1, @diogohaussen

  • Contributors RGN, AP, WB, DCH are the gauarantor of this project and contributed to the conception as well as design of the study. RGN, AP, WB, MA, ARA-B, PK, KFL, JEDA, RAH, VMP, MAA, AJY, BSJ, MJG, BP, JLAL, SF, OMM, KD, LES, HJC, ICT, YK, AC, AG, ES, AMD, PB, JS, PN, DRC, ASP, JE, ECP, DFK, DCH contributed to acquisition and analysis of data. RGN, AP, WB, MHM, LSV, FF, HA, NRB contributed to drafting the text or preparing figures.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests RGN reported consulting fees for advisory roles with Anaconda, Biogen, Cerenovus, Genentech, Hybernia, Imperative Care, Medtronic, Phenox, Philips, Prolong Pharmaceuticals, Stryker Neurovascular, Shanghai Wallaby, and Synchron and stock options for advisory roles with Astrocyte, Brainomix, Cerebrotech, Ceretrieve, Corindus Vascular Robotics, Vesalio, Viz-AI, RapidPulse, and Perfuze, and investments in Viz-AI, Perfuze, Cerebrotech, Reist/Q’Apel Medical, Truvic, and Viseon. WB is a consulting medical director for MIVI Neurovascular, consultant for Cerenovus, Microvention, Stryker, Medtronic, Imperative Care and receives research funding from Cerenovus, Brainomix, NIH. ARA-B is a consultant for Stryker Neurovascular. RAH is a consultant for Stryker, Medtronic, Cerenovous, Microvention, Balt, Phenox, Rapid Medical, and Q’Apel. He is on the advisory board for MiVI, eLum, Three Rivers, Shape Medical, and Corindus. AJY receives grants from Medtronic, Cerenovus, Penumbra, Stryker, and Penumbra. He is a consultant for Cerenovus, Penumbra, Vesalio, Zoll, Philips, Rapid Medical, and StrokeNet (MOST trial). AJY also has equity interest in Insera Therapeutics and Nicolab. MJG has been a consultant on a fee-per-hour basis for Alembic LLC, Astrocyte Pharmaceuticals, BendIt Technologies, Cerenovus, Imperative Care, the Jacob’s Institute, Medtronic Neurovascular, Mentice, Mivi Neurosciences, phenox GmbH, Q’Apel, Route 92 Medical, Scientia, Stryker, Wallaby Medical; holds stock in Imperative Care, InNeuroCo, Galaxy Therapeutics and Neurogami; and has received research support from the National Institutes of Health (NIH), the United States – Israel Binational Science Foundation, Anaconda, ApicBio, Arsenal Medical, Axovant, Balt, Cerenovus, Ceretrieve, CereVasc LLC, Cook Medical, Galaxy Therapeutics, Gentuity, Gilbert Foundation, Imperative Care, InNeuroCo, Insera, Jacob’s Institute, Magneto, Microvention, Medtronic Neurovascular, MIVI Neurosciences, Naglreiter MDDO, Neurogami, Philips Healthcare, Progressive Medical, Pulse Medical, Rapid Medical, Route 92 Medical, Scientia, Stryker Neurovascular, Syntheon, ThrombX Medical, Wallaby Medical, the Wyss Institute and Xtract Medical. KD is supported by a grant from Science Foundation Ireland (SFI) and the European Regional Development Fund (ERDF) under grant number 13/RC/2073_P2. ASP is a consultant for Medtronic Neurovascular, Stryker Neurovascular, Balt, Q’Apel Medical, Cerenovus, Microvention, Imperative Care, Agile, Merit, CereVasc and Arsenal Medical and receives research grants from NIH, Microvention. DCH is a consultant for Stryker,Cerenovus and is a member of the Data and Safety Monitoring Board for Vesalio and Jacobs Institute. He also holds stock options of VizAI. The other authors have no competing interests to disclose.

  • Provenance and peer review Not commissioned; externally peer reviewed.