Abstract Number: Esoc2026a2447 Susceptibility or Hyperdense Vessel Sign and Intravenous Thrombolysis Before Endovascular Treatment: An Individual Participant Data Meta-Analysis of Six Randomized Clinical Trials

Abstract Background and aims Imaging markers of clot composition, including susceptibility vessel sign (SVS) on MRI and hyperdense vessel sign (HVS) on CT, may influence responsiveness to intravenous thrombolysis (IVT). We examined whether the effect of IVT before endovascular treatment (EVT) differs according to the presence of SVS or HVS. Methods We performed an individual participant data meta-analysis of six randomized clinical trials comparing IVT+EVT versus EVT alone. SVS and HVS were centrally assessed on baseline imaging. A two-stage meta-analysis was conducted to estimate within-trial treatment effects by SVS/HVS status, followed by random-effects pooling. Effect modification was assessed using interaction terms. The primary outcome was the ordinal 90-day modified Rankin Scale. Safety outcomes included symptomatic intracranial hemorrhage. Results Baseline imaging was evaluable in 1982/2313 participants (CT n=1740; MRI n=242). SVS was present in 88% of MRIs; HVS in 69% of CTs. Overall, 71% had SVS/HVS. IVT+EVT was not associated with improved functional outcome compared with EVT alone (adjusted common OR acOR 1.08, 95%CI 0.87–1.36). In explorative analyses, IVT+EVT was associated with better outcomes among patients with SVS/HVS(acOR 1.25, 95%CI 1.03–1.51), but not without SVS/HVS (acOR 0.85, 95%CI 0.63–1.14; p-interaction=0.081). Intracranial hemorrhage rates were numerically higher with IVT regardless of SVS/HVS status. Conclusions Imaging markers suggestive of erythrocyte-rich thrombi did not significantly modify benefit of IVT+EVT. Numerically larger point estimates for benefit of IVT+EVT among patients with SVS/HVS warrant further investigation. Conflict of interest Roman Rohner: nothing to disclose. Fabiano Cavalcante: nothing to disclose. Dr Kaesmacher reports grants from Le Studium and grants from the Swiss National Science Foundation (SNSF) to other. Kilian Treurniet: nothing to disclose. Manon Kappelhof: nothing to disclose. Kazumi Kimura: nothing to disclose. Bernard Yan: nothing to disclose. Pengfei Yang: nothing to disclose. Wenjie Zi: nothing to disclose. Dr Majoie reports grants from European Commission to other; grants from Health Evaluation Netherlands to other; grants from Stryker Corporation to other; stock holdings in Nicolab; grants from Dutch Heart Foundation to other; and grants from Boehringer Ingelheim to other. Urs Fischer: reports funding from Medtronic, Stryker, Rapid medical, Phenox, Penumbra, Swiss National, Science Foundation, CSL Behring, Alexion/Portola, Boehringer Ingelheim and Biogen. SD reports institutional funding from the National Health and Medical Research Council and funding from Medtronic, Abbott and CSL Behring for participation on data safety monitoring board or advisory board.