Net Water Uptake at CT Predicts the Treatment Effect of Thrombectomy for Low ASPECTS Stroke

Background: Recent trials have demonstrated that supplementing best medical treatment (BMT) with endovascular thrombectomy (EVT) improves the functional outcomes of patients presenting with large ischemic lesions. Purpose: To analyze whether net water uptake (NWU), quantified as infarct hypoattenuation at admission noncontrast CT, modifies the treatment effect of EVT and may aid in patient selection. Materials and Methods: The Efficacy and Safety of Thrombectomy in Stroke with Extended Lesion and Extended Time Window, or TENSION, trial was a randomized, multicenter clinical trial that enrolled patients with anterior circulation stroke and an Alberta Stroke Program Early CT Score of 3—5. NWU was quantified as relative hypoattenuation within the acute infarct lesion at admission CT. The primary outcome was the 90-day modified Rankin scale (mRS) score. Associations between NWU and functional outcomes were evaluated via ordinal and logistic regression analyses. The effect of NWU on treatment efficacy was assessed through interaction terms between NWU and EVT. Results: A total of 207 patients were included (median NWU, 16.4%; IQR, 11.7%—20.3%). Higher NWU was an independent predictor of higher mRS scores on day 90 (adjusted common odds ratio, 1.11; 95% CI: 1.06, 1.17; P <. 001), whereas EVT was associated with lower mRS scores (adjusted common odds ratio, 0.33; 95% CI: 0.18, 0.59; P <. 001). There was a significant interaction term between EVT and NWU (P <. 002), suggesting greater treatment efficacy in patients with low NWU. EVT in patients with an NWU of less than 15.0% was associated with a greater probability of achieving an mRS of less than or equal to 3, whereas greater NWU was associated with less effective EVT. Conclusion: The degree of NWU at admission CT modified the treatment effect of EVT in patients with large infarct cores. EVT was associated with improved outcomes only in patients with lower NWU, whereas in patients with an NWU of at least 15%, EVT plus BMT did not show a functional benefit over BMT alone.