For patients with acute ischemic stroke, endovascular thrombectomy within six
hours after the onset of symptoms can improve outcomes. Patients with a
disproportionately high NIH Stroke score given the size of the ischemic area on
perfusion imaging (so called "clinical infarct mismatch") are more likely to
recover function after thrombectomy. The DAWN trial tested whether patients in
whom brain imaging showed proximal anterior cerebral vessel occlusion and
clinical infarct mismatch would benefit from thrombectomy 6 to 24 hours after
the onset of an ischemic stroke. Two hundred six patients were randomly assigned to
receive thrombectomy or standard medical care. The patients were then assessed at
90 days after stroke. The primary outcome of post-stroke disability on the Utility-
Weighted modified Rankin Scale showed a mean score of 5.5 for the
thrombectomy group versus 3.4 for the standard care group, a
statistically significant difference. Functional independence was achieved in
49% of patients in the thrombectomy group versus 13%
in the standard care group. Procedural complications occurred in
7% of patients in the thrombectomy group. The rate of other
adverse events, such as symptomatic intracranial hemorrhage and death, was
similar between groups. The trial was stopped at 31 months when a
planned interim analysis showed the superiority of thrombectomy. The authors
conclude that in patients with acute anterior circulation stroke with
clinical-infarct mismatch, thrombectomy performed within six to 24 hours
significantly reduced disability and improved functional independence at
90 days as compared with standard medical care. Full trial results are
available at NEJM.org.