Abstract WMP10: A Closer Look at Late Window Thrombectomy Selection

Abstract

Introduction: The DAWN and DEFUSE 3 studies established thrombectomy as standard care for patients with emergent large vessel occlusions (ELVO) presenting 6-24 hours after symptom onset. Given the greater inclusivity of DEFUSE 3 we evaluated the effect of thrombectomy in DEFUSE 3 patients who would have been excluded from DAWN. Methods: Eligibility criteria of the DAWN trial were applied to DEFUSE 3 patient data to identify DEFUSE 3 patients not meeting DAWN criteria (DEFUSE 3 Non-DAWN). Reasons for DAWN exclusion in DEFUSE 3 were infarct core too large (CTL), NIHSS 6-9 and mRS 2. Subgroups were compared to the DEFUSE 3 Non-Dawn and entire DEFUSE 3 cohorts. Results: There were 71 DEFUSE 3 Non-DAWN patients; 31 patients with NIHSS 6-9, 33 with CTL, and 13 with pre-morbid mRS 2 (some patients met multiple criteria). For CTL patients, median 24-hour infarct volume was 119ml (IQR 74.6-180) versus 31.5ml (IQR 17.6-64.3) for Core Not Too Large (CNTL) patients, p= <0.001. Complications and functional outcomes were similar between the groups. Thrombectomy in CTL patients compared to the remaining DEFUSE 3 Non-Dawn patients conveyed benefit for functional outcome (OR 20.9, CI 1.3-337.8). Comparing the NIHSS 6-9 group with the NIHSS ≥10 patients, mRS 0-2 outcomes were achieved in 74% versus 22% (p=<0.001), with mortality in 6% versus 23% (p=0.024) respectively. For patients with NIHSS 6-9 compared to the remaining DEFUSE 3 Non-Dawn patients thrombectomy conveyed a better chance of functional outcome (OR 1.86, CI 0.36-9.529); results lacked statistical significant in this small subgroup. Conclusions: Patients with pretreatment core infarct volumes <70ml but too large for inclusion by DAWN criteria demonstrate robust benefit from endovascular therapy. More permissive pretreatment core thresholds in core-clinical mismatch selection paradigms may be appropriate. Despite a trend towards benefit of thrombectomy in patients with NIHSS 6-9 additional data regarding late window thrombectomy for these patients is needed.