BackgroundPre-stroke dependent patients (modified Rankin Scale score (mRS) ≥3) were excluded from most trials on endovascular treatment (EVT) for acute ischemic stroke (AIS) in the anterior circulation. Therefore, little evidence exists for EVT in those patients. We aimed to investigate the safety and benefit of EVT in pre-stroke patients with mRS score 3.MethodsWe used data from the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic stroke in the Netherlands (MR CLEAN) Registry. All patients treated with EVT for anterior circulation AIS with pre-stroke mRS 3 were included. We assessed causes for dependence and compared patients with successful reperfusion (defined as expanded Thrombolysis in Cerebral Ischemia scale (eTICI) 2b–3) to patients without successful reperfusion. We used regression analyses with pre-specified adjustments. Our primary outcome was 90-day mRS 0–3 (functional improvement or return to baseline).ResultsA total of 192 patients were included, of whom 82 (43%) had eTICI <2b and 108 (56%) eTICI ≥2b. The median age was 80 years (IQR 73–87). Fifty-one of the 192 patients (27%) suffered from previous stroke and 36/192 (19%) had cardiopulmonary disease. Patients with eTICI ≥2b more often returned to their baseline functional state or improved (n=26 (26%) vs n=15 (19%); adjusted odds ratio (aOR) 2.91 (95% CI 1.08 to 7.82)) and had lower mortality rates (n=49 (49%) vs n=50 (64%); aOR 0.42 (95% CI 0.19 to 0.93)) compared with patients with eTICI <2b.ConclusionsAlthough patients with AIS with pre-stroke mRS 3 comprise a heterogenous group of disability causes, we observed improved outcomes when patients achieved successful reperfusion after EVT.