Thrombectomy between 6 and 24 hours after acute stroke reduces disability: The DAWN trial

1. Thrombectomy performed between 6 and 24 hours after onset of acute stroke in patients with a mismatch between stroke symptoms and infarct volume results in better disability outcomes compared to standard care alone.

2. Adverse events of intracranial hemorrhage and 90-day mortality do not differ significantly between thrombectomy and standard care-treated patients.

Evidence Rating: 1 (Excellent)

Study Rundown: Acute stroke management with thrombectomy aims to increase cerebral perfusion in order to minimize ischemic damage. Prior studies have indicated a clinical advantage to performing thrombectomy within 6 hours of stroke onset, with decreasing clinical benefit as time to thrombectomy increases. After 6 hours from stroke onset relatively fewer studies are available to aid in determining optimal stroke management with thrombectomy. In this study, the DAWN (DWI or CTP Assessment with Clinical Mismatch in the Triage of Wake-Up and Late Presenting Strokes Undergoing Neurointervention with Trevo) trial compares stroke patients with a mismatch between their clinical deficits and infarct volume treated 6 to 24 hours after symptom onset with thrombectomy plus standard care compared to standard care alone. Primary endpoints of disability and functional independence were both improved in the thrombectomy group compared to the standard treatment group at 90 days post treatment. Rates of internal hemorrhage and 90-day mortality did not significantly differ between the two groups.

This study provides significant evidence supporting thrombectomy treatment between 6 and 24 hours after stroke onset. Study strengths include participation of numerous multinational treatment centers and extensive subgroup analysis, and a notable weakness is exclusion of patients with large volume infarcts.

Click to read the study, published today in NEJM

Relevant Reading: Time to endovascular reperfusion and degree of disability in acute stroke

In-Depth [randomized controlled trial]: This prospective, multicenter trial conducted between 2014 and 2017 randomized 206 patients to thrombectomy plus standard care (n = 107) and standard care (n = 99) groups. Eligible patients had occlusion of either the intracranial internal carotid artery, proximal middle cerebral artery, or both with a last known well time between 6 and 24 hours prior to treatment. Included patients also had a mismatch between their clinical symptom severity and infarct volume as defined by the National Institutes of Health Stroke Scale (NIHSS). Concomitant stenting was not performed in the thrombectomy group. The modified Rankin scale was used to assess co-primary endpoints of disability and functional independence.

Patients in the thrombectomy group were less disabled at 90 days post-treatment compared to the standard care group (5.5 vs 3.4 Rankin score, respectively; 95% confidence interval 1.1 to 3.0). Rates of functional independence at 90 days were 49% in the thrombectomy group and 13% in the control group (adjusted difference 33%; 95% credible interval 22 to 40). Subgroup analysis indicated significantly improved disability scores for thrombectomy-treated patients for almost all assessments (except for unwitnessed stroke). Rates of intracerebral hemorrhage (6% vs 3%, p = 0.50) and 90-day mortality (19% vs 18%, p = 1.00) did not differ between the thrombectomy and standard care groups, respectively.

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