O09 Early lesion water uptake modifies the treatment effect of mechanical thrombectomy in patients with low ASPECTS – A secondary analysis of the efficacy and safety of thrombectomy in stroke with extended lesion and extended time window (TENSION) tr

<h3>Introduction</h3> The beneficial effect of endovascular treatment (EVT) on functional outcome in patients with ischemic stroke and low ASPECTS has recently been demonstrated. ASPECTS rating is based on the presence of ischemic lesion hypodensity, however the degree of hypoattenuation, directly indicating net water uptake (NWU), has not been considered for treatment selection.. <h3>Aim of Study</h3> We hypothesized that the effect of EVT on functional outcome in low ASPECTS patients depends on early lesion NWU. <h3>Methods</h3> The TENSION trial was a randomized multicenter clinical trial including patients with anterior circulation stroke and ASPECTS 3-5. Net water uptake (NWU) was assessed as quantitative imaging biomarker on admission-CT. Primary endpoint was the rate of functional independence defined as modified Rankin Scale (mRS) 0-2 at day-90. The effect of EVT on functional outcome was analyzed according to the degree of NWU within the early infarct lesion. <h3>Results</h3> For this pilot study, 120 patients were included (51 EVT patients, 42%; 69 BMT patients). In patients with functional independence, the median NWU was 7.7% (IQR:4.7-9.0), which was lower compared to patients with mRS≥3 (median 12.1, IQR:9.3-16.6,p&lt;0.001). In inverse-probability weighting analysis, the average treatment effect of EVT on functional independence was 27.4% (95%CI:13.5-41.3%) for patients with low NWU (&lt;7.7%), while the effect of EVT in patients with high NWU (&gt;7.7%) was 6.5% (95%CI:-0.1-14.3%) <h3>Conclusion</h3> The degree of relative lesion hypodensity on admission-CT (ie. NWU) modified the effect of EVT on functional outcome and should be considered as image criterion besides ASPECTS to select patients for EVT, particularly in borderline cases. <h3>Disclosure of Interest</h3> no.