BackgroundTo assess if leukoaraiosis severity is associated with outcome in patients with acute ischemic stroke (AIS) following endovascular thrombectomy, and to propose a leukoaraiosis-related modification to the ASPECTS score.MethodsA retrospective review was completed of AIS patients that underwent mechanical thrombectomy for anterior circulation large vessel occlusion. The primary outcome measure was 90-day mRS. A proposed Leukoaraiosis-ASPECTS (“L-ASPECTS”) was calculated by subtracting from the traditional ASPECT based on leukoaraiosis severity (1 point subtracted if mild, 2 if moderate, 3 if severe). L-ASEPCTS score performance was validated using a consecutive cohort of 75 AIS LVO patients.Results174 patients were included in this retrospective analysis: average age: 68.0±9.1. 28 (16.1%) had no leukoaraiosis, 66 (37.9%) had mild, 62 (35.6%) had moderate, and 18 (10.3%) had severe. Leukoaraiosis severity was associated with worse 90-day mRS among all patients (P=0.0005). Both L-ASPECTS and ASPECTS were associated with poor outcomes, but the area under the curve (AUC) was higher with L-ASPECTS (P<0.0001 and AUC=0.7 for L-ASPECTS; P=0.04 and AUC=0.59 for ASPECTS). In the validation cohort, the AUC for L-ASPECTS was 0.79 while the AUC for ASPECTS was 0.70. Of patients that had successful reperfusion (mTICI 2b/3), the AUC for traditional ASPECTS in predicting good functional outcome was 0.80: AUC for L-ASPECTS was 0.89.ConclusionsLeukoaraiosis severity on pre-mechanical thrombectomy NCCT is associated with worse 90-day outcome in patients with AIS following endovascular recanalization, and is an independent risk factor for worse outcomes. A proposed L-ASPECTS score had stronger association with outcome than the traditional ASPECTS score.