ABSTRACT NUMBER: ESOC2026LT25 EFFECT OF BASELINE STROKE SEVERITY ON THE BENEFIT AND SAFETY OF INTRAVENOUS THROMBOLYSIS PRIOR TO ENDOVASCULAR TREATMENT: RESULTS FROM IRIS INDIVIDUAL PARTICIPANT DATA META-ANALYSIS

Abstract Background and aims Whether baseline stroke severity modifies the effect of intravenous thrombolysis (IVT) prior to endovascular treatment (EVT) in patients with acute anterior circulation large vessel occlusion (LVO) is uncertain, particularly regarding the risk of intracranial hemorrhage in severe strokes. We aim to assess the heterogeneity of IVT prior to EVT on clinical outcomes based on baseline NIHSS scores. Methods Two thousand three hundred thirteen patients with anterior circulation LVO who presented directly to EVT-capable centers from six randomized-controlled trials were analyzed. In the primary analysis, effect modification of IVT prior to EVT by baseline NIHSS scores was assessed using multivariable ordinal regression with interaction terms. Secondary analyses evaluated the heterogeneity of IVT prior to EVT by different time windows in severe stroke patients. Results There was no statistically significant effect modification of IVT prior to EVT on the functional outcome by baseline NIHSS scores (adjusted p-interaction = 0.579). For severe stroke patients, there was no effect heterogeneity of IVT prior to EVT on the complication of any hemorrhage by different time windows (adjusted p-interaction = 0.500 and 0.508 for NIHSS > 25; p-interaction = 0.819 and 0.408 for and NIHSS ≥ 20, respectively). Conclusions Among patients with acute anterior circulation LVO presenting directly to EVT-capable centers within 4.5 hours, there is no evidence to suggest that stroke severity can direct the decision-making process for administering IVT prior to EVT. For severe stroke patients, IVT prior to EVT did not significantly increase the risk of hemorrhagic transformation, regardless of the time window. Conflict of interest