CT (Computerized Tomography) for Late EndovasculAr Reperfusion

Non-Contrast CT vs CTP or MRI Selection vs Medical Management in Late Presentation of Large Vessel Occlusion Stroke, 6-24 Hours. A Multicenter Retrospective Study

The objective of this multicenter, retrospective, cross-sectional, chart review study is to compare outcomes (disability, complications and mortality) of patients with large vessel occlusion stroke presenting at late time window selected by either Non-Contrast CT (NCCT) only, advanced imaging with CTP (Computed Tomography Perfusion), MRI (Magnetic Resonance Imaging), or medical management.

Boston Medical Center (BMC) will serve as the main data coordinating site. Fifteen additional sites will seek local IRB approval or ethics approval. The aggregated de-identified data will be analyzed comparing types of interventions and outcomes by type of imaging or medical management.

Additional subgroup analysis that are planned include:

1. Futile Reperfusion in the Extended Window.

   We will evaluate clinical, imaging and time metric factors associated with successful reperfusion yet poor outcomes (modified Rankin 3-6) in the 6-24 hour window.

   An evaluation of factors associated with symptomatic intracranial hemorrhage and mortality will be conducted.

2. Pre-Stroke disability.

   1. EVT patients treated in the extended window compared to Medical Management
   2. EVT patients treated in the extended window with pre-existing disability vs. those without pre-existing disability

3. Intravenous Thrombolysis in the Extended Window

   We aim to compare the safety and outcomes of bridging IVT in patients with acute ischemic stroke due to large vessel occlusion (LVO) who underwent EVT 6 to 24 hours after time-last-known-well.

4. Medical Management vs CT selected Patients

   We hypothesize that in patients with large vessel occlusion in the anterior circulation presenting in the 6 to 24 hour window, patients who are selected by non-contrast CT and treated with endovascular therapy have more favorable outcomes (ordinal mRS shift) as compared to patients who are medically managed.

5. Sex differences in the Extended Window

   In this study we aim to asses whether there are sex differences in clinical outcomes and safety of EVT in patients presenting in the 6-24 hour time window.

6. Transfer Analysis

It is not well established whether transfer patients presenting in the extended window should have repeat imaging upon receipt at the endovascular center after an interim time window.

We hypothesize that within a 0 to 2, or 2 to 4 hour delay between images of the primary stroke center to receiving endovascular center, transferred patients in the extended window, who undergo thrombectomy with successful reperfusion will have similar outcomes in patients with or without repeat imaging at the receiving center.

We aim to compare the safety and outcomes of late-window bridging IVT vs. direct EVT for LVO acute ischemic stroke in the 6-24 hour time window.

Inclusion Criteria:

• Patients presenting 6-24 hours from last known well with large vessel occlusion stroke
• ASPECTS score 5 or greater from last known well
• January 1, 2014 to May 1, 2022

Exclusion Criteria:

-Time last seen well to treatment <6 hours from last known well