Endovascular treatment in anterior circulation stroke beyond 6.5 hours after onset or time last seen well: results from the MR CLEAN Registry.

Background: Randomised controlled trials with perfusion selection have shown benefit of endovascular treatment (EVT) for ischaemic stroke between 6 and 24 hours after symptom onset or time last seen well. However, outcomes after EVT in these late window patients without perfusion imaging are largely unknown. We assessed their characteristics and outcomes in routine clinical practice.
Methods: The Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands Registry, a prospective, multicentre study in the Netherlands, included patients with an anterior circulation occlusion who underwent EVT between 2014 and 2017. CT perfusion was no standard imaging modality. We used adjusted ordinal logistic regression analysis to compare patients treated within versus beyond 6.5 hours after propensity score matching on age, prestroke modified Rankin Scale (mRS), National Institutes of Health Stroke Scale, Alberta Stroke Programme Early CT Score (ASPECTS), collateral status, location of occlusion and treatment with intravenous thrombolysis. Outcomes included 3-month mRS score, functional independence (defined as mRS 0-2), and death.
Results: Of 3264 patients who underwent EVT, 106 (3.2%) were treated beyond 6.5 hours (median 8.5, IQR 6.9-10.6), of whom 93 (87.7%) had unknown time of stroke onset. CT perfusion was not performed in 87/106 (80.2%) late window patients. Late window patients were younger (mean 67 vs 70 years, p<0.04) and had slightly lower ASPECTS (median 8 vs 9, p<0.01), but better collateral status (collateral score 2-3: 68.3% vs 57.7%, p=0.03). No differences were observed in proportions of functional independence (43.3% vs 40.5%, p=0.57) or death (24.0% vs 28.9%, p=0.28). After matching, outcomes remained similar (adjusted common OR for 1 point improvement in mRS 1.04, 95% CI 0.56 to 1.93).
Conclusions: Without the use of CT perfusion selection criteria, EVT in the 6.5-24-hour time window was not associated with poorer outcome in selected patients with favourable clinical and CT/CT angiography characteristics. randomised controlled trials with lenient inclusion criteria are needed to identify more patients who can benefit from EVT in the late window.
Competing Interests: Competing interests: Erasmus MC received funds from Stryker and Bracco Imaging by DWJD. MUMC received funds from Stryker and Codman for consultations by WHvZ. WHvZ and RJvO are principal investigators for the MR CLEAN-LATE trial. R-JBG and FAVP are coordinating researchers for MR CLEAN-LATE. CBLMM received funds from TWIN Foundation (related to this project, paid to institution) and from CVON/Dutch Heart Foundation, Stryker, European Commission, Health Evaluation Netherlands (unrelated; all paid to institution). YBWEMR, CBLMM and IGHJ are shareholders of Nico.lab, a company that focuses on the use of artificial intelligence for medical imaging analysis. RL reports institutional fees from Ischamaview for consultancy. The other authors had no conflicting interests.
(© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY. Published by BMJ.)