Real-world implementation and outcomes of extended-window intravenous thrombolysis in Catalonia, 2016-2024: A population-based study using the CICAT registry.

Background. Evidence supporting intravenous thrombolysis (IVT) beyond 4.5 hours is based on selected populations using advanced imaging, while real-world data remains limited. We describe its uptake, selection strategies, treatment pathways, and outcomes in routine practice. Methods. We conducted a population-based observational study using the prospective multicenter CICAT registry in Catalonia, Spain (2016-2024). Patients receiving extended-window IVT (>4.5 hours or unknown onset) were grouped into IVT alone and IVT before mechanical thrombectomy (bridging therapy), with conventional-window patients as a clinical reference. Excellent functional outcome was defined as a 90-day modified Rankin Scale (mRS) 0–1 or return to prestroke mRS, and good functional outcome as mRS 0–2 or return to prestroke mRS. Safety outcomes were symptomatic intracranial hemorrhage (sICH) and mortality. Results. Among 12,547 patients treated with IVT, 656 (5.2%) received extended-window treatment (450 IVT alone; 206 bridging therapy). The proportion treated in the extended window increased from 3.5% in 2016-2018 to 7.4% in 2022-2024, with perfusion imaging predominantly guiding patient selection (84.1%). In the IVT alone cohort, excellent functional outcome occurred in 42.8% of extended-window and 47.2% of conventional-window patients; sICH occurred in 3.6% and 2.3%, and mortality in 12.9% and 12.5%, respectively. Corresponding outcomes in the bridging cohort 40.0% and 45.1% for good functional outcome, 20.6% and 18.6% for mortality, and 5.8% and 4.1% for sICH respectively. Differences with the reference group were also generally modest among patients aged >80 years and those with prestroke disability. Conclusions. Extended-window IVT was progressively adopted across a population-based stroke network, predominantly using advanced imaging. Among selected patients, observed differences in functional and safety outcomes relative to the conventional-window reference group were generally modest, including in populations underrepresented in randomized trials. These findings should be interpreted in the context of differences in patient selection and case mix between treatment windows.