Abstract T MP3: Collaterals Predicts Imaging Evolution and Patient Outcomes in Acute Ischemic Stroke Patients

Background: Collateral flow and early ischemic changes on CT are pivotal determinants of outcome in patients with large artery occlusion (LAO). Evolution of stroke occurs during inter-facility transfer. We sought to evaluate the association between collaterals and stroke evolution measured by ASPECTS decay and the relationship of these imaging findings with patient outcomes. Methods: In a cross-sectional multicenter study, we evaluated 313 transferred patients with AIS and LAO (MCA or ICA) from 01/08-04/14. The collateral score (CS) (Figure 1) and ASPECTS were measured. Good collaterals were defined as scores 2-3 (poor; scores 0-1). ASPECTS decay was defined as dichotomized deterioration in ASPECTS from good (8-10) to bad (0-7) during transfer. ASPECTS was also analyzed as an ordinal variable. Logistic regression and mediation analyses were performed to evaluate the association between the collaterals, ASPECTS and patients good and poor (mRS 0-2 and 4-6, respectively) outcomes. Results: Table 1 depicts baseline characteristics. Patients with poor CS had greater odds of ASPECTS decay during transfer (OR 13.4, 95%CI 7.5-24, p<0.0001), which was associated with higher odds of mRS 4-6 (OR 7.1, 95%CI 3.7-13.8, p<0.0001). The association between poor CS and poor outcome was maintained after adjustment for ASPECTS decay, stroke severity and IV tPA treatment (OR 10.9, 95%CI 4-34, p<0.0001). For every 30 minutes in transfer time, the odds of ASPECTS decay increased by 13% (OR 1.13, 95%CI 1.05-1.2, P 0.0004). With each 1 point drop in ASPECTS, the odds of good outcome were reduced by 42% (OR 0.58, 95%CI 0.54-0.66, P < 0.0001). On mediation analysis, ASPECTS decay explained 75% of the relationship between poor CS and poor outcome (Sobel 2.11, p 0.03) after adjusting for IV tPA treatment and stroke severity. Conclusion: Our cohort shows that stroke evolution is determined by transfer time and collateral flow, which are pivotal determinants of clinical outcome in patients with AIS and LAO.