Perfusion Imaging and Clinical Outcome in Acute Ischemic Stroke with Large Core.

Objective Mechanical thrombectomy (MT) is not recommended for acute stroke with large vessel occlusion (LVO) and a large volume of irreversibly injured tissue (“core”). Perfusion imaging may identify a subset of patients with large core who benefit from MT. Methods We compared two cohorts of LVO-related patients with large core (>50 ml on diffusion-weighted-imaging or CT-perfusion using RAPID), available perfusion imaging, and treated within 6 hrs from onset by either MT + Best Medical Management (BMM) in one prospective study, or BMM alone in the pre-MT era from a prospective registry. Primary outcome was 90-day modified Rankin Scale≤2. We searched for an interaction between treatment group and amount of penumbra as estimated by the mismatch ratio (MMRatio = critical hypoperfusion/core volume). Results Overall, 107 patients were included (56 MT + BMM + 51 BMM): Mean age was 68 ± 15 yrs, median core volume 99 ml (IQR: 72-131) and MMRatio 1.4 (IQR: 1.0-1.9). Baseline clinical and radiological variables were similar between the 2 groups, except for a higher intravenous thrombolysis rate in the BMM group. The MMRatio strongly modified the clinical outcome following MT (Pinteraction 1.2 (adjusted OR [95%CI] = 6.8 [1.7-27.0] vs. 0.7 [0.1-6.2], respectively). Similar findings were present for MMRatio≥1.8 in the subgroup with core≥70 ml. Parenchymal hemorrhage on follow-up imaging was more frequent in the MT + BMM group regardless of the MMRatio. Interpretation Perfusion imaging may help select which patients with large core should be considered for MT. Randomized studies are warranted. This article is protected by copyright. All rights reserved.