IntroductionLimited data is available about the outcomes of mechanical thrombectomy (MT) in stroke patients presenting with a large core infarct. We aim to investigate the safety and efficacy of MT in patients with large vessel occlusion and Alberta Stroke Program Early CT Score (ASPECTS) of 2-5.MethodsData from Stroke Thrombectomy and Aneurysm Registry (STAR), which combined the prospectively maintained databases of 28 thrombectomy-capable stroke centers in the US, Europe, and Asia, was interrogated. We identified thrombectomy patients presenting with an occlusion in the Internal carotid artery (ICA) or M1 segment of the middle cerebral artery (MCA). Multivariable regression analysis was performed to assess factors associated with favorable 90-day outcome (modified Rankin scale 0-3), including interaction terms between ASPECTS 2-5 and receiving MT in the extended window (≥ 6 hours from symptom-onset).ResultsAmong MT patients who presented with ICA or M1 occlusion, 2132 had ASPECTS≥6 and 213 patients had ASPECTS 2-5. Patients in the low ASPECTS group were younger (70 vs. 72 years old, P=0.003) and more likely to present with an ICA occlusion (47.9% vs. 28.8%, P<0.001) compared to patients with ASPECTS≥6. At 90 days, mRS 0-3 was observed in 36.6% of the patients who presented with ASPECTS 2-5 (42% in patients who had successful recanalization and 10.8% in patients who had failed recanalization, P=0.001) (figure 1). Lower ASPECTS and presenting in the extended window were both associated with worse 90- day outcomes after controlling for potential confounders, without significant interaction between these two factors.ConclusionMore than one in three patients presenting with ASPECTS (2-5) may achieve favorable 90-day functional outcome following MT. Favorable outcome was 4 times higher in low ASPECTS patients who had successful recanalization. The effect of low ASPECTS on 90-day outcome did not differ in patients presenting in the early versus extended MT window.Abstract O-011 Figure 1Disclosures E. Almallouhi: None. S. Al Kasab: None. Z. Hubbard: None. G. Porto: None. A. Alawieh: None. R. Chalhoub: None. E. Bass: None. P. Jabbour: None. R. Starke: None. S. Wolfe: None. A. Arthur: None. I. Maier: None. J. Grossberg: None. A. Rai: None. M. Park: None. J. Mascitelli: None. M. Psychogios: None. R. De Leacy: None. D. Raper: None. T. Dumont: None. M. Levitt: None. A. Polifka: None. J. Osbun: None. R. Crosa: None. J. Kim: None. W. Casagrande: None. M. Mokin: None. C. Matouk: None. A. Shaban: None. I. Fragata: None. A. Yoo: None. A. Spiotta: 1; C; Stryker, Penumbra, and Medtronic. 2; C; Penumbra, Stryker, Cerenovus, Terumo.