Workload and clinical impact of MRI-based extension of reperfusion therapy time window in acute ischaemic stroke—a prospective single-centre study

Current European Stroke Organisation (ESO) guidelines recommend extended time window reperfusion therapies (4.5-9 h for thrombolysis, 6-24 h for thrombectomy) based on advanced imaging. However, the workload and clinical benefit of this strategy on a population basis are not known. To determine the caseload, treatment rates, and outcomes in the extended as compared to the standard time windows. All consecutive ischaemic stroke patients within 24 h of last known well between 1st March 2021 and 28th February 2022 were included in a prospective single-centre study. Treatment eligibility in the extended time windows or wake-up strokes recognized within 4 h was based on current ESO guideline criteria using MRI DWI-PWI or DWI-FLAIR mismatch. MRI was only available during working hours (8-20 h); otherwise, CT/CTA was used. Clinical outcome in treated patients was assessed at three months. Among the 777 admitted patients, 252 (32.4%) had MRI. The thrombolysis rate was 119/304 (39.1%) in standard and 14/231 (6.1%) in the extended time window. The thrombectomy rate was 34/386 (8.8%) in standard and 15/391 (3.8%) in the extended time window. Independent clinical outcomes (mRS ≤ 2) were not statistically different in early and late-treated patients both for thrombolysis (48% vs. 28.6%, p = 0.25) and thrombectomy (38.4% vs. 33.3%, p = 0.99). Even with a limited availability of advanced imaging extending therapeutic time windows resulted in an 11.7% increase in thrombolysis and a 44% increase in thrombectomy with comparable clinical outcomes in early and late-treated patients at the price of a twofold burden in clinical and advanced imaging screening.