ABSTRACT NUMBER: ESOC2026YS181 LATE-WINDOW REPERFUSION THERAPY IN ACUTE ISCHEMIC STROKE IN DENMARK: A NATIONWIDE REGISTER-BASED COHORT STUDY

Abstract Background and aims Timely reperfusion therapy is essential in acute ischemic stroke (AIS). In 2018, treatment windows expanded to include intravenous thrombolysis (IVT) for patients with unknown onset and endovascular therapy (EVT) up to 24 hours. The nationwide implementation of these extensions remains incompletely evaluated. This study aims to describe nationwide trends in late-window reperfusion therapy use, and to compare functional outcomes between patients treated within versus beyond conventional time windows. Methods This nationwide cohort study uses prospectively collected data from the Danish Stroke Registry linked with the Danish National Patient Registry. All adult AIS patients treated with IVT or EVT between 2018 and 2023 were included. Temporal trends in IVT and EVT use will be described, stratified by unknown onset and time from onset to treatment. Functional outcomes will be evaluated using the modified Rankin Scale (mRS) at 3 months. Outcomes will be compared between IVT-treated patients with known versus unknown onset and between EVT-treated patients treated <6 versus ≥6 hours from symptom onset. The primary outcome is favourable functional outcome, defined as mRS of 0–1 for IVT- and 0–2 for EVT-treated. Results Between 2018 and 2023, 72,096 AIS episodes were registered in Denmark. Of these, 17.1 % (n=12,291) received IVT, and 5.6 % (n=4,022) underwent EVT. Among patients treated with reperfusion therapy, the median age was 72 years (IQR 62-80), 40.7% were female (n=5,882), and the median NIHSS score at admission was 5 (IQR 3-9). Analyses of temporal trends and functional outcomes across treatment groups will be presented at the conference. Conflict of interest Supported by grants from TrygFonden. The funder had no role in the design, conduct, analysis, or reporting of this study