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Association between time to treatment and clinical outcomes in endovascular thrombectomy beyond 6 hours without advanced imaging selection
  1. Permesh Singh Dhillon1,2,
  2. Waleed Butt3,
  3. Anna Podlasek2,
  4. Norman McConachie1,
  5. Robert Lenthall1,
  6. Sujit Nair1,
  7. Luqman Malik1,
  8. Pervinder Bhogal4,
  9. Hegoda Levansri Dilrukshan Makalanda4,
  10. Oliver Spooner5,
  11. Kailash Krishnan6,
  12. Nikola Sprigg6,7,
  13. Alex Mortimer8,
  14. Thomas Calvert Booth9,10,
  15. Kyriakos Lobotesis11,
  16. Philip White12,
  17. Martin A James13,14,15,
  18. Philip Bath6,7,
  19. Robert A Dineen2,16,
  20. Timothy J England7,17,18
  1. 1 Interventional Neuroradiology, Queens Medical Centre Nottingham University Hospitals NHS Trust, Nottingham, UK
  2. 2 NIHR Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK
  3. 3 Interventional Neuroradiology, Queen Elizabeth Hospital University Hospitals Birmingham NHS Trust, Birmingham, UK
  4. 4 Interventional Neuroradiology, The Royal London Hospital Barts Health NHS Trust, London, UK
  5. 5 Stroke Medicine, The Royal London Hospital Barts Health NHS Trust, London, UK
  6. 6 Stroke Medicine, Queen's Medical Centre Nottingham University Hospital NHS Trust, Nottingham, UK
  7. 7 Strokes Trial Unit, Mental Health & Clinical Neuroscience, University of Nottingham, Nottingham, UK
  8. 8 Interventional Neuroradiology, Southmead Hospital North Bristol NHS Trust, Bristol, Bristol, UK
  9. 9 Department of Neuroradiology, King's College Hospital NHS Foundation Trust, London, London, UK
  10. 10 School of Biomedical Engineering and Imaging Sciences, King's College London, London, London, UK
  11. 11 Interventional Neuroradiology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, London, UK
  12. 12 Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
  13. 13 University of Exeter Medical School, Exeter, UK
  14. 14 Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
  15. 15 Sentinel Stroke National Audit Programme, King’s College London, London, UK
  16. 16 Radiological Sciences, Mental Health & Clinical Neuroscience, University of Nottingham, Nottingham, UK
  17. 17 Stroke, Mental Health and Clinical Neuroscience, School of Medicine, Nottingham University Hospitals NHS Trust, Nottingham, UK
  18. 18 Stroke, University Hospitals of Derby and Burton NHS Foundation Trust, Derby, UK
  1. Correspondence to Dr Permesh Singh Dhillon, Interventional Neuroradiology, Nottingham University Hospitals NHS Trust, Nottingham NG7 2UH, UK; permesh.dhillon{at}


Background The effectiveness and safety of endovascular thrombectomy (EVT) in the late window (6–24 hours) for acute ischemic stroke (AIS) patients selected without advanced imaging is undetermined. We aimed to assess clinical outcomes and the relationship with time-to-EVT treatment beyond 6 hours of stroke onset without advanced neuroimaging.

Methods Patients who underwent EVT selected with non-contrast CT/CT angiography (without CT perfusion or MR imaging), between October 2015 and March 2020, were included from a national stroke registry. Functional and safety outcomes were assessed in both early (<6 hours) and late windows with time analyzed as a continuous variable.

Results Among 3278 patients, 2610 (79.6%) and 668 (20.4%) patients were included in the early and late windows, respectively. In the late window, for every hour delay, there was no significant association with shift towards poorer functional outcome (modified Rankin Scale (mRS)) at discharge (adjusted common OR 0.98, 95% CI 0.94 to 1.01, p=0.27) or change in predicted functional independence (mRS ≤2) (24.5% to 23.3% from 6 to 24 hours; aOR 0.99, 95% CI0.94 to 1.04, p=0.85). In contrast, predicted functional independence was time sensitive in the early window: 5.2% reduction per-hour delay (49.4% to 23.5% from 1 to 6 hours, p=0.0001). There were similar rates of symptomatic intracranial hemorrhage (sICH) (3.4% vs 4.6%, p=0.54) and in-hospital mortality (12.9% vs 14.6%, p=0.33) in the early and late windows, respectively, without a significant association with time.

Conclusion In this real-world study, there was minimal change in functional disability, sICH and in-hospital mortality within and across the late window. While confirmatory randomized trials are needed, these findings suggest that EVT remains feasible and safe when performed in AIS patients selected without advanced neuroimaging between 6–24 hours from stroke onset.

  • CT angiography
  • stroke
  • thrombectomy
  • intervention
  • CT perfusion

Data availability statement

Data may be obtained from a third party and are not publicly available. Data access requests should be directed to SSNAP as the data provider and HQIP as the data controller.

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Data availability statement

Data may be obtained from a third party and are not publicly available. Data access requests should be directed to SSNAP as the data provider and HQIP as the data controller.

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  • Twitter @PermeshSD, @hldmak

  • Contributors Conception and design: PSD, WB. Acquisition of the data: PSD. Analysis and interpretation of the data: PSD, AP, WB. Critical revision of the manuscript: PSD, WB, AP, NM, RL, SN, LM, PBl, HLDM, OS, KK, NS, AM, TCB, KL, PW, MAJ, PBh, RAD, TJE. Study supervision: RAD, TJE. Guarantor of this work: PSD. All authors approved the final version of the manuscript.

  • Funding SSNAP is commissioned by the Health Quality Improvement Partnership and funded by the National Health Service (NHS) England and the Welsh Government. MAJ is supported by the National Institute for Health Research Applied Research Collaboration South West Peninsula. TCB is supported by the Wellcome/EPSRC Centre for Medical Engineering [WT 203148/Z/16/Z].

  • Disclaimer The views expressed in this publication are those of the author(s) and not necessarily those of the National Institute for Health Research or the Department of Health and Social Care. No specific funding was sought for this study.

  • Competing interests PBh is Stroke Association Professor of Stroke Medicine and an Emeritus NIHR Senior Investigator. MAJ has received lecture and consultancy fees from Medtronic. PBl has a consulting agreement with Phenox, Balt, Braniomix, Neurovasc Technologies and Cerenovus. PW serves on the editorial board of the Journal of NeuroInterventional Surgery. No other disclosures or competing interests declared by the remaining authors.

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

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.