Application of the DAWN clinical imaging mismatch and DEFUSE 3 selection criteria: benefit seems similar but restrictive volume cut-offs might omit potential responders

Background and purpose: An external validation of the selection criteria of diffusion-weighted imaging or computerized tomography perfusion assessment with clinical mismatch in the triage of wake-up and late-presenting strokes undergoing the Neurointervention with Trevo (DAWN) and the Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke (DEFUSE3) trials was conducted in a cohort of unknown onset stroke (UOS) patients treated with thrombectomy. Methods: A validation cohort of UOS patients was selected from a prospectively collected thrombectomy database to match the inclusion criteria of DAWN and DEFUSE 3. Patients with an initial National Institutes of Health Stroke Scale (NIHSS) ≥10 were stratified according to the DAWN selection criteria. Patients ≤90 years old with an initial NIHSS ≥6 were stratified according to the DEFUSE 3 selection criteria. The proportions of patients with a modified Rankin Scale (mRS) ≤2 at 3 months follow-up were compared between DAWN-eligible patients and the DAWN trial thrombectomy group, and between DEFUSE 3-eligible patients and the DEFUSE 3 trial thrombectomy group. Results: Of the 60/102 (59%) DAWN-eligible patients, 26 patients (43%) reached a mRS ≤2 at 3 months follow-up [versus 52/107 patients (49%) in the DAWN trial thrombectomy group; P = 0.52]. Of the 100/117 (85%) DEFUSE 3-eligible patients, 48 patients (48%) reached a mRS ≤2 at 3 months follow-up [versus 41/92 patients (45%) in the DEFUSE 3 trial thrombectomy group; P = 0.67]. Of the DAWN-ineligible and DEFUSE 3-ineligible patients who underwent thrombectomy, 38% (16/42) and 41% (7/17) of patients reached a mRS ≤2, respectively. Conclusion: The results of the DAWN and DEFUSE 3 trials were externally validated in a UOS cohort where the trials' selection criteria identified a similar proportion of responders to thrombectomy.