With follow up extended to two years, functional independence was significantly better in patients treated with thrombectomy in the six- to 24-hour time window than in patients treated with medical therapy alone.

Selected patients with acute ischaemic stroke who are treated in the six- to 24-hour time window after ischaemic stroke onset can benefit from endovascular thrombectomy (EVT). Some previous clinical trials selected patients based on perfusion imaging, which is not available at all centres. The partially industry-funded, phase 3, MR CLEAN-LATE trial determined eligibility based on the appearance of collateral vessels on computed tomographic angiography (CTA). The trial previously showed a benefit at 90 days (NEJM JW Neurol May 11 2023 and Lancet 2023; 401: 1371-1380). In this prespecified analysis, the authors assessed outcomes at two years.

Over a four-year period, researchers randomly assigned 502 patients (mean age, 74 years; 52% women) in the six- to 24-hour time window after stroke onset or time when last seen normal to EVT plus medical therapy or medical therapy alone. Median NIH Stroke Scale score was 10 and the time from when last seen well to arrival at the endovascular centre averaged 12 hours. The proximal middle cerebral artery was the most common site of vessel occlusion. Patients had to have at least some collateral flow evident on CTA. The modified Rankin Scale (mRS) score at two years was the primary outcome. The median mRS at two years was four in the EVT group and six in the control group. For functional independence (mRS, zero to two), the rates were 35% in the EVT patients and 27% in the control group. Mortality at two years did not differ between the treatment groups.

Comment: This extended analysis shows a benefit up to two years after the thrombectomy procedure. However, about 12 patients need to be treated to provide one additional patient with functional independence, a higher number needed to treat than observed in studies of EVT provided in the early time window (e.g. N Engl J Med 2015; 372: 2285-2295). Selection based on collateral vessels provides clinicians with another option for identifying patients suitable for EVT.

Seemant Chaturvedi, MD, Stewart J. Greenebaum Endowed Professor of Stroke Neurology and Stroke Program Director, University of Maryland Medical System, Baltimore; Vice-Chair for Strategic Operations, Department of Neurology, University of Maryland, Baltimore, USA., Stewart J. Greenebaum Endowed Professor of Stroke Neurology and Stroke Program Director, University of Maryland Medical System, Baltimore; Vice-Chair for Strategic Operations, Department of Neurology, University of Maryland, Baltimore, USA.

Huijberts I, et al. Collateral-based selection for endovascular treatment of acute ischaemic stroke in the late window (MR CLEAN-LATE): 2-year follow-up of a phase 3, multicentre, open-label, randomised controlled trial in the Netherlands. Lancet Neurol 2024; 23: 893-900.

The summary is taken from the following Journal Watch title: Neurology