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Small thrombus size, thrombus composition, and poor collaterals predict pre-interventional thrombus migration
  1. Peter B Sporns1,2,
  2. Hermann Krähling3,
  3. Marios N Psychogios1,
  4. Astrid Jeibmann4,
  5. Jens Minnerup5,
  6. Gabriel Broocks2,
  7. Lukas Meyer2,
  8. Alex Brehm1,
  9. Moritz Wildgruber3,6,
  10. Jens Fiehler2,
  11. Helge Kniep2,
  12. Uta Hanning2
  1. 1 Department of Neuroradiology, Clinic for Radiology & Nuclear Medicine, University Hospital Basel, Basel, Switzerland
  2. 2 Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
  3. 3 Institute of Clinical Radiology, University Hospital of Muenster, Albert-Schweitzer-Campus 1, Muenster, Germany
  4. 4 Institute of Neuropathology, University Hospital Muenster, Pottkamp 2, Münster, Germany
  5. 5 Department of Neurology with Institute of Translational Neurology, University Hospital of Muenster, Albert-Schweitzer-Campus 1, Muenster, Germany
  6. 6 Klinik und Poliklinik für Radiologie, Klinikum der Universität München, Muenchen, Germany
  1. Correspondence to Dr Peter B Sporns, Department of Neuroradiology, University Hospital Basel, Basel 4031, Switzerland; peter.sporns{at}


Background Different imaging characteristics such as clot burden score, collaterals, and pre-interventional thrombus migration are associated with functional outcome in patients with acute ischemic stroke. Moreover, histological thrombus composition is associated with pre-interventional thrombus migration. We hypothesized that smaller clots may more likely migrate and that collateral status in ischemic stroke patients may mediate this tendency of the clot to migrate.

Methods In this prospective cohort of consecutive ischemic stroke patients, clot burden scores and collateral scores were rated and the retrieved thrombi were histologically analyzed. We then investigated the relationship between clot burden score, probability for thrombus migration, and collateral scores using mediation analysis.

Results 163 patients are included of which 36 (22.1%) had a clot migration. Probability of thrombus migration was significantly associated with lower collateral scores (P<0.01), higher clot burden scores (P<0.01), shorter thrombi (P<0.01), and higher RBC count (P<0.01). In the mediator pathway, higher collateral scores were significantly associated with higher clot burden scores (P<0.01) and younger age (P=0.029). The total effect of an increase in clot burden score by one grade on thrombus migration is composed of the direct effect (+18%, P<0.01) and the collateral score-mediated indirect effect (−5%, P<0.01).

Conclusions Smaller, erythrocyte-rich thrombi tend to migrate more often. Good collaterals seem to have a considerable effect on limiting migration. This supports the hypothesis that larger clots have stronger adherence with the vessel wall and that good collaterals increase the counter pressure distal of the clot.

  • stroke
  • thrombectomy
  • angiography

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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  • PBS, HK, HK and UH contributed equally.

  • Contributors All authors contributed to study design, data collection, interpretation, and writing and revising the manuscript.

  • 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 None declared.

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