UMEM Educational Pearls

• The DAWN trial was a multicenter, randomized, open-label study comparing endovascular thrombectomy plus standard medical care with standard medical care alone for patients with:
  • Acute stroke symptoms
  • Last known well 6 to 24 hours earlier
  • Evidence of intracranial ICA or proximal MCA occlusion
  • Mismatch between clinical deficit and infarct volume on CTA or MRA
• The study found that patients receiving thrombectomy plus standard medical care had improved functional independence at 90 days as defined by modified Rankin Scale (mRS) of 0, 1, or 2 (49% vs 13%).
• The trial was stopped early based on prespecified interim analysis intended with the adaptive trial design.
• While the two treatment groups were similar, with median NIHSS score of 17, they had small infarct volumes and short time from symptom observation (4.8 vs 5.6 hours) compared to time of patient's last known well (12.2 vs 13.3 hours). 
• 88% of the patients had unwitnessed stroke onset (including wake-up strokes), thus it is possible that these patients had actual ischemia times closer to 6 hours, thereby reproducing similar results as prior thrombectomy trials.

Bottom Line: The use of neuroimaging to identify an ischemic penumbra that may benefit from thrombectomy may be considered even for patients with time of last known well beyond 6 hours.

Additional Information

• Endovascular thrombectomy is recommended for patients with large vessel occlusion within 6 hours of stroke symptom onset.
• Eligibility has been based on the time that patient was last known to be well.
• Prior studies suggest that patients who have evidence of ischemic brain tissue that has not yet infarcted could benefit from reperfusion even when performed more than 6 hours after patient was last known to be well.
• The DAWN (DWI or CTP Assessment with Clinical Mismatch in the Triage of Wake-Up and Late Presenting Strokes Undergoing Neurointervention with Trevo) trial enrolled 206 patients from 26 sites over 29 months.  
• It is unclear how many patients were screened for enrollment.
• This study was sponsored by Stryker Neurovascular and only allowed the use of their Trevo endovascular stent retriever device for the thrombectomy group.

References

Nogueira RG, Jadhav AP, Haussen DC, et al. Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct. N Engl J Med. 2017 Nov 11. [Epub ahead of print]

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