Thrombectomy appears to be safe and feasible in patients with acute ischemic stroke due to LVO meeting all DAWN trial criteria but treated beyond 24 hours of TLKW with outcomes comparable to patients in the DAWN trial intervention arm. Further studies are warranted to validate these findings.

Of all patients with acute ischemic stroke presenting to a single comprehensive stroke center, 1.7% of patients qualified for DAWN clinical trial enrollment with an additional 0.6% to 1% qualifying for the DEFUSE-3 trial. These data predict an increase in thrombectomy utilization with important implications for comprehensive stroke center resource optimization and stroke systems of care.

Approximately 70% (n=142) of the 204 patients presenting 6-24 hours after last known well with NIH Stroke Scale score ≥6 and harboring an ACLVO are DAWN and/or DEFUSE-3 ineligible, most commonly due to large infarct burden (38%). 26% (n=37) of trial ineligible patients with large vessel occlusion strokes received off-label ET and 30% of them achieved functional independence (modified Rankin Scale 0-2) at 90 days. Rates of symptomatic intracranial hemorrhage and mortality were 8% and 24%, respectively CONCLUSION: Trial ineligible patients with large vessel occlusion strokes receiving off-label ET achieved outcomes comparable to DAWN and DEFUSE-3 eligible patients. Patients aged <80 years are most likely to benefit from ET in this subgroup. These data indicate a larger population of patients who can potentially benefit from ET in the expanded time window if more permissive criteria are applied.

Purpose of the ReviewThis article reviews recent breakthroughs in the treatment of acute ischemic stroke, mainly focusing on the evolution of endovascular thrombectomy, its impact on guidelines, and the need for and implications of next-generation randomized controlled trials.Recent FindingsEndovascular thrombectomy is a powerful tool to treat large vessel occlusion strokes and multiple trials over the past 5 years have established its safety and efficacy in the treatment of anterior circulation large vessel occlusion strokes up to 24 hours from stroke onset.SummaryIn 2015, multiple landmark trials (MR CLEAN, ESCAPE, SWIFT PRIME, REVASCAT, and EXTEND IA) established the superiority of endovascular thrombectomy over medical management for the treatment of anterior circulation large vessel occlusion strokes. Endovascular thrombectomy has a strong treatment effect with a number needed to treat ranging from 3 to 10. These trials selected patients based on occlusion location (proximal anterior occlusion: internal carotid or middle cerebral artery), time from stroke onset (early window: up to 6–12 hours), and acceptable infarct burden (Alberta Stroke Program Early CT Score [ASPECTS] ≥6 or infarct volume <50 mL). In 2017, the DAWN and DEFUSE-3 trials successfully extended the time window up to 24 hours in appropriately selected patients. Societal and national thrombectomy guidelines have incorporated these findings and offer Class 1A recommendation to a subset of well-selected patients. Thrombectomy ineligible stroke subpopulations are being studied in ongoing randomized controlled trials. These trials, built on encouraging data from pooled analysis of early trials (HERMES collaboration) and emerging retrospective data, are studying large vessel occlusion strokes with mild deficits (National Institutes of Health Stroke Scale <6) and large infarct burden (core volume >70 mL).