Endovascular Thrombectomy Beyond 24 Hours From Last Known Well: A Pooled Multicenter International Cohort

Background: Limited data are available on endovascular thrombectomy (EVT) efficacy and safety in large vessel occlusion (LVO) patients presenting >24hr from last known well (LKW). We compared outcomes between patients receiving EVT and best medical management (MM) in a multicenter international cohort. Methods: Consecutive patients with anterior circulation LVO presenting >24h after LKW from 13 centers from 7/2012-4/2021 were analyzed. Multivariable models for 90d mRS distribution and symptomatic ICH were adjusted for age, NIHSS, glucose, IV tPA, transfer status, clot location, time from LKW, CT ASPECTS and ischemic core (rCBF<30%) and Tmax >6s volumes. Results: Of 240 patients with a median (IQR) LKW to presentation 28.3h (24.9-38.2), 153 (64%) received EVT. Baseline characteristics were similar except for NIHSS (EVT: 13 (8-20) vs MM: 17 (10-22), p=0.005), CT ASPECTS (EVT: 8(6-9) vs MM: 4(3-6), p<0.001) and ischemic core 2.5(0-13) vs 15(0-71) mL, p<0.001. EVT was associated with a better shift in 90d mRS (acOR: 2.45, 95% CI=1.42-4.22, p=0.001), higher functional independence (42% vs 10%, aOR: 4.84, 95% CI=2.02-11.64, p<0.001) and numerically lower mortality (22% vs 42%, aOR: 0.50, 95% CI=0.23-1.06, p=0.071), Fig 1A. However, EVT was associated with numerically higher sICH (5.5% vs 0%, p=0.10). Following EVT, 82% achieved successful reperfusion (mTICI 2b-3), which was associated with better shift in 90d mRS (acOR: 5.82, 95% CI: 1.77-19.10, p=0.004), higher functional independence (44% vs 22%, aOR: 5.03, 95% CI: 0.87-29.12, p=0.07) and lower mortality (20% vs 52%, aOR: 0.08, 95% CI: 0.01-0.57, p=0.01), Fig 1B. Conclusions: EVT may be associated with better functional outcomes, despite numerically increased risk of sICH in patients presenting with anterior circulation LVO beyond 24 hours. Further prospective studies are warranted.