Abstract 72: Refining The Pre-treatment Noncontrast CT ASPECTS Threshold For IAT Selection: Pooled Analysis Of The Penumbra Pivotal Study And PICS Registry

Abstract

Background: Previous studies have demonstrated that the Alberta Stroke Program Early CT Score (ASPECTS) on pre-treatment noncontrast CT (NCCT) can be used to identify patients who will benefit from intra-arterial therapy (IAT). Specifically, an ASPECTS threshold of 7 has been identified as clinically important. We sought to test this threshold and further characterize the clinical impact of pre-treatment ASPECTS (pre-ASPECTS) in a large IAT cohort. Materials and methods: We identified anterior circulation acute ischemic stroke patients treated with the Penumbra Stroke System in the Pivotal Study and the Penumbra Imaging Collaborative Study (PICS). Inclusion criteria for this analysis were evaluable pre-treatment NCCT and available 90-day modified Rankin Scale (mRS) score. Expert readers graded ischemic change on NCCT using ASPECTS and blinded to all clinical information except stroke side. Results: Of 221 patients who fulfilled study criteria, the mean age was 66.0±15.1 years, and median NIHSS score was 16 (IQR 12-21). The cohort was 50.9% (112/220) female. There were 111 (50.2%) right-sided strokes. The target vessel occlusion involved the ICA in 21.9% (48/219), MCA in 77.6% (170/219) and ACA in 0.5% (1/219). The median ASPECTS was 7 (IQR 6-9). TIMI 2-3 reperfusion was achieved in 83% (181/218). Good outcome (mRS 0-2) was achieved in 77 (34.8%) patients at 90 days. Adjusting for age, NIHSS and reperfusion, pre-treatment ASPECTS was an independent predictor of good outcome (O.R. 1.47; 95%C.I.:1.23 to 1.76). Pre-ASPECTS >7 predicted good outcome with a relative risk of 1.80 (95%C.I.:1.23 to 2.64). The proportion of good outcomes was exceedingly low among pre-ASPECTS 0-4 (2.8% [1/36]; Figure ). When trichotomizing pre-ASPECTS at 0-4 (n=36), 5-7 (n=76) and 8-10 (n=109), the median 90-day mRS scores were 6 (IQR 4-6), 3.5 (IQR 2-6) and 3 (IQR 1-4), respectively (p<0.0001). In pairwise comparison, the only significant differences were between pre-ASPECTS 0-4 and the other groups. While there was no effect of reperfusion on outcome among pre-ASPECTS 0-4, TIMI 2-3 reperfusion (p=0.04) and earlier timing of reperfusion (none vs. <300 minutes vs. ≥300 minutes; p=0.03) were associated with better outcomes among pre-ASPECTS 5-10. Conclusions: Pre-treatment NCCT ASPECTS is a critical determinant of outcome following IAT. Pre-ASPECTS 0-4 identifies a population of patients who are highly likely to have dismal outcomes and do not benefit from endovascular reperfusion.