This trial demonstrated an overall benefit in function outcome at 90 days in the treatment group (mRS score 0 2, 49% versus 13%; adjusted difference, 33% [95% CI, 21 44]; posterior probability of superiority >0.999).51 In DAWN, there were few strokes with witnessed onset (12%). The DEFUSE 3 trial used perfusion-core mismatch and maximum core size as imaging criteria to select patients with large anterior circulation occlusion 6 to 16 hours from last seen well for mechanical thrombectomy. This trial showed a benefit in functional outcome at 90 days in the treated group (mRS score 0 2, 44.6% versus 16.7%; RR, 2.67 Benefit was independently demonstrated for the subgroup of patients who met DAWN eligibility criteria and for the subgroup who did not. DAWN and DEFUSE 3 are the only RCTs showing benefit of mechanical thrombectomy >6 hours from onset. Therefore, only the eligibility criteria from one or the other of these trials should be used for patient selection. Although future RCTs may demonstrate that additional eligibility criteria can be used to select patients who benefit from mechanical thrombectomy, at this time, the DAWN or DEFUSE 3 eligibility should be strictly adhered to in clinical practice.51,52 See Table XVII in online Data Supplement 1. 3.7.4. Technique COR LOE New, Revised, or Unchanged Use of stent retrievers is indicated in preference to the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) device. I A Recommendation unchanged from 2015 Endovascular. The technical goal of the thrombectomy procedure should be reperfusion to a modified Thrombolysis in Cerebral Infarction (mTICI) grade 2b/3 angiographic result to maximize the probability of a good functional clinical outcome. I A Recommendation reworded for clarity from 2015 Endovascular. See Table XCV in online Data Supplement 1 for original wording. Mechanical thrombectomy aims to achieve reperfusion, not simply recanalization. 