ABSTRACT NUMBER: ESOC2026A1999 EFFECT OF INTRAVENOUS THROMBOLYSIS ACCORDING TO AN AUTOMATED PREDICTED CORE VOLUME ON NCCT IN THE EXTENDED TIME WINDOW

Abstract Background and aims We explored whether an automated predicted core volume (aCore) on non-contrast CT (NCCT) using a deep-learning algorithm modifies the benefit and safety of intravenous-thrombolysis (IVT) in the extended time-window. Methods This multicenter study pooled two cohorts of consecutive stroke patients arriving 4.5–24 hours from onset (Jan-2019 to Dec-2021). IVT patients were treated per CTP-EXTEND criteria. aCore was later evaluated on NCCT using a validated algorithm (Methinks, Spain). Inverse probability weighting was adjusted for age, baseline NIHSS, occlusion-status, sex, and onset-to-arrival time. Interaction models (IVT × aCore) assessed mRS-shift at 3-months, favorable outcome (mRS 0–2), and symptomatic intracranial hemorrhage (sICH). Linear and spline-based interaction terms were evaluated, and bootstrapping (400resamples) was used to estimate probabilities of benefit or harm. Results Among 976 patients (mean age 74, median NIHSS 10, median onset-to-admission 605 minutes, mean aCore 12.5 mL), 155 received thrombolysis (36 bridging;IVT + EVT) and 826 received no-reperfusion. Favorable outcome occurred in 42% and sICH in 5%. Linear models showed a significant IVT-by-aCore interaction: each additional aCore mL increased IVT benefit by ~ 2% on mRS-shift (OR0.98, 95% CI0.97–1.00, P < 0.01) and 4% on favorable outcome (OR1.04, 95% CI1.02–1.05; P < 0.01). No interaction was observed for sICH. Spline analyses revealed a progressive benefit up to ~ 50 mL, followed by attenuation; sICH risk rose non-linearly beyond this range(Figures 1-2). Conclusions NCCT-based aCore significantly modifies the effect of IVT in the extended-window. Thresholds near 50 mL may define functional benefit and sICH risk, supporting its use as a pragmatic selection tool. Conflict of interest Dr Ortega-Gutierrez: Grants: NIH-NINDS (R01NS127114-01, R03NS126804), PCORI, Stryker, Medtronics, Microvention, IschemiaView, Viz.ai, and Siemens. Consultant: Medtronic and Stryker Neurovascular. Dr Ribó is the Chief Medical Office of Methinks and has equity interests. Consultant: AptaTargets, Cerenovus, Medtronic, Philips, Stryker. Stock: Anaconda, Nora. Figure 1 - belongs to Results Figure 2 - belongs to Conclusions