Imaging perfusion deficits and thrombolysis safety and efficacy in acute ischaemic stroke. The Third International

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Scientific Abstract|Design: Main trial: IST-3 is an international, prospective, randomised, open, blinded end-point (PROBE) controlled trial of i.v. rt-PA within 6 hours of onset of acute ischaemic stroke (www.ist3.com). Plain CT brain scanning is the prime imaging modality for the main trial. Perfusion study: In centres where MR or CT perfusion are part of routine acute stroke care, the data from patients who have MR diffusion weighted imaging (DWI) and perfusion weighted imaging (PWI), or CT with perfusion (CTP) imaging at baseline before entry in IST3 will be collected and analysed centrally in addition to their non-contrast CT or MR DWI. We will measure infarct growth between baseline and 24-48 hour follow-up imaging, among patients with versus without DWI/PWI or CTP mismatch, with rt-PA versus control in patients with perfusion data. |Setting: Main trial: Hospitals in the UK, Europe, North America, Australia, with stroke units where evidence-based care pathways for stroke (including for administration of rt-PA) are in use. IST-3 currently has 97 active centres (+ 86 who may join) in 12 countries worldwide. Perfusion study: Of these, 12 centres are using MR for baseline assessment instead of CT, eight have already sent 12 MR PWI data and five have sent 23 CTP scans in acute stroke. |Project timetables including recruitment rate: IST-3 Main trial: stops recruitment in late 2011. Recruitment is on target. All regulatory approvals (including Human Research Ethics Committee approvals in 97 centres in 12 countries), randomisation, central data collection are in place. The IST-3-perfusion study: can start immediately. The centres that are already using perfusion imaging are some of the most active in IST-3. |Therefore we estimate that over the next 3 years, in 15 active centres, recruiting between four and eight patients per year each, the perfusion study will include between 100 and 300 patients. Based on scan data received so far, we anticipate a rate of two CTP to one MR PWI although a higher rate of four CTP to one MR DWI is possible. Both will provide valuable data. |Ultimately, we will contribute the perfusion data to an international collaboration performing an individual patient data metaanalysis of perfusion imaging.