Delayed Endovascular Stroke Treatment - Beyond the 6-hour Window

Spoon Feed
Patients with acute stroke from occluded intracranial internal carotid artery (ICA) or proximal middle cerebral artery (MCA) presenting 6-24 hours from onset benefitted from endovascular thrombectomy when clinical deficits of stroke were greater than expected based on infarct volume on diffusion-weighted MRI or perfusion CT.  NNT for functional independence = 2.8. 

Why does this matter?
The goal for tPA in stroke is under 4.5 hours, preferably under 3.  The goal for endovascular treatment (stent retriever) is under 6 hours.  But what if patients present with a proximal vessel occlusion over 6 hours?

Fish that clot outta there
This was a RCT of patients with proximal clot in the intracranial ICA or proximal MCA presenting over 6 hours from the time of onset.  To be included, they had to have a larger clinical neurological deficit than what was expected based on measured stroke volume in mL on MRI or CT perfusion.  They enrolled 207 patients, about half of whom had the intervention and half usual care.  The study was stopped early because the intervention group had significantly better outcome on a disability scale, with 49% being functionally independent after endovascular treatment vs only 13% with usual care at 90 days.  There was no 90-day mortality difference.  Patients with proximal clot causing stroke may still benefit from invasive therapy well beyond the 6 hour window, which means calling in the stroke team or referral to a stroke center much later than we are accustomed to doing.

Source
Thrombectomy 6 to 24 Hours after Stroke with a Mismatch between Deficit and Infarct.  N Engl J Med. 2017 Nov 11. doi: 10.1056/NEJMoa1706442. [Epub ahead of print]

Peer reviewed by Thomas Davis, MD.

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