RT Journal Article SR Electronic T1 E-166 External validation of dawn: benefit seems similar but restrictive selection criteria might omit potential responders JF Journal of NeuroInterventional Surgery JO J NeuroIntervent Surg FD BMJ Publishing Group Ltd. SP A131 OP A131 DO 10.1136/neurintsurg-2018-SNIS.242 VO 10 IS Suppl 2 A1 Blanc, R A1 Ducroux, C A1 Khoury, N A1 Lecler, A A1 Piotin, M A1 Fahed, R YR 2018 UL http://jnis.bmj.com/content/10/Suppl_2/A131.1.abstract AB Purpose We aimed to conduct an external validation of the selection criteria of the diffusion-weighted-imaging or computerized-tomography-perfusion assessment with clinical mismatch in the triage of wake-up and late-presenting strokes undergoing Neurointervention with Trevo (DAWN) trial1,2 in a cohort of unknown onset stroke (UOS) patients treated with thrombectomy.Materials and methods A study cohort of UOS patients was selected from a prospectively collected thrombectomy database to match the inclusion criteria of DAWN. Patients were stratified according to DAWN Groups A/B/C. Group A criteria identified patients≥80 years old with a NIHSS ≥10 + DWI volume <21 cc; Group B: patients<80 years old with a NIHSS ≥10 + DWI volume <31 cc; and Group C: patients<80 years old with a NIHSS ≥20 + DWI volume ≥31 and<51 cc. We compared proportions of patients with a modified Rankin Scale (mRS)≤2 at 3 months follow-up between DAWN-eligible patients and the study cohort and the DAWN trial thrombectomy group.Results Out of 102 patients, 60 (59%) were defined as DAWN-eligible. Among these, 26 patients (43%) reached a mRS ≤2 at 3 months follow-up (vs. 52/107 patients [49%] in the DAWN trial thrombectomy group; p=0.52) (figure 1). The proportion of DAWN-ineligible patients for Groups A/B/C with a mRS ≤2 were 2/13 patients (15%), 12/22 patients (55%), and 2/7 patients (29%), respectively.Abstract E-166 Figure 1 All DAWN thrombectomy patients, DAWN-eligible and DAWN-inteligle patients in study cohortConclusion The results of the DAWN trial were externally validated in a UOS cohort where the trial’s selection criteria identified a similar proportion of responders to thrombectomy. Additional trials are needed to address benefit in patients with larger infarct volumes who were not eligible for DAWN.ReferencesJovin TG, Saver JL, Ribo M, et al. Diffusion-weighted imaging or computerized tomography perfusion assessment with clinical mismatch in the triage of wake up and late presenting strokes undergoing neurointervention with Trevo (DAWN) trial methods. Int J Stroke 2017:1747493017710341.Nogueira RG, Jadhav AP, Haussen DC, et al. Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct. New England Journal of Medicine 2017.Disclosures R. Blanc: None. C. Ducroux: None. N. Khoury: None. A. Lecler: None. M. Piotin: None. R. Fahed: None.