Infarct growth rate modifies treatment benefit in anterior circulation large vessel occlusion stroke: direct thrombectomy or bridging therapy

The optimal reperfusion strategy for acute large vessel occlusion (LVO) stroke remains uncertain between direct endovascular thrombectomy (EVT) and bridging therapy. This study explored the potential interaction between infarct growth rate (IGR) and these treatment strategy on clinical outcomes. This retrospective study included anterior circulation LVO patients undergoing EVT. IGR was calculated as baseline infarct volume divided by onset-to-imaging time. Patients were stratified into low- and high-IGR groups according to the median value. The primary outcome was favorable functional outcome (modified Rankin Scale 0–2) at 90 days. Multivariable logistic regression assessed categorical, continuous, and restricted cubic spline IGR-by-treatment interactions. Propensity score overlap weighting was performed as a sensitivity analysis. Among 174 patients, 80 (46.0%) achieved favorable outcomes. The median IGR was 6.6 (IQR 0.6–23.5) mL/h. Compared with high IGR, low IGR was associated with higher rates of favorable outcome (52.9% vs. 39.1%, p = 0.047) and lower mortality (9.2% vs. 25.3%, p = 0.008). A significant interaction between categorical IGR and treatment strategy was observed for favorable outcome ( p = 0.038), although attenuated after overlap weighting (P for interaction = 0.095). The interaction was not reproduced when IGR was modeled continuously or with restricted cubic splines. In the high-IGR subgroup, bridging therapy was associated with higher odds of favorable outcome than direct EVT (50.0% vs. 25.6%; OR 2.90, 95% CI 1.16–7.24). Categorical analyses suggested IGR modified the treatment effect between direct EVT and bridging therapy in anterior LVO stroke, and patients with high IGR might benefit more from bridging therapy than direct EVT.