Abstract W P36: Timing Of Collateral Circulation In Acute Stroke And Its Effect On Predicting Outcomes

Background: We previously reported that Miteff scoring system on pre-tPA CTA was able to predict good functional outcomes in AIS, conversely substantial collateral recruitment on the 24hr CTA led to worse outcomes. We now aimed to determine if the degree of collateral circulation at a specific timing affects its ability to prognosticate outcomes. Methods: Patients treated with IV-tPA during 2018-2012 were included. Patients were stratified by onset-to-CTA timing from 0-60, 61-120, 121-180 and >180 minutes. Two independent neuroradiologists evaluated intracranial collaterals using the Miteff’s system, Maas system, and Alberta Stroke Program Early CT score (ASPECTS) 20-point methodology. Good and severely poor outcomes at 3-months were defined by modified Rankin Scale (mRS) score of 0-1 points and 5-6 points, respectively. SICH was intracranial bleed with NIHSS increase of ≥4 points. Results: 250 Consecutive AAIS patients were included. 52 patients in the 0-60 group, 89 in the 61-120 group, 59 in the 121-180 group and 40 patients in the >180 group. On multivariate analysis from 0-120 minutes, good collaterals by Miteff classification showed a trend to good outcomes (OR 2.460 95%CI 0.985- 9.770, p =0.06) and significantly prevented severely poor outcomes (OR 0.199 95% CI 0.053-0.743, p=0.016) and SICH (OR 0.196 95%CI 0.045-0.862, p=0.03). However the association with prevention of unfavourable outcomes was no longer present in the 121 -180 and > 180 minutes groups. Conclusions: Good collaterals are associated with better functional outcomes however this benefit may be time dependent.