Abstract W P38: Collateral Circulation Status Correlates With Aspects Decay During Inter-facility Transfer After Anterior Acute Ischemic Stroke Patients

Abstract

Introduction: The collateral circulation plays an important role in the dynamic process of cerebral ischemia. The aim of this study is to determine if collateral status correlates with the early ischemic changes measured by the rate of Alberta Stroke Program Early CT Scores (ASPECTS) decay in emergently transferred acute ischemic stroke patients with anterior large vessel conclusions. Material and methods: We retrospectively analyzed the data of patients referred to our comprehensive stroke center from 7 outside hospitals between January 15, 2006 and January 15, 2014. Collateral status was assessed using an initial CT angiography obtained before treatment, and graded as "Good" (the entire medial cerebral artery reconstitutes with contrast) or "Poor" (partial or no reconstitution of the distal medial cerebral artery), by two independent reviewers (CA and WD). ASPECTS decay was calculated in the following ways: 1. Absolute ASPECTS decay: (A1-A2)/T, 2. Relative ASPECTS decay: [(A1-A2)/A1]/T 3. Net ASPECTS difference: (A1-A2) and 4. Relative ASPECTS difference: (A1-A2)/A1; where A1= ASPECTS 1st CT, A2= ASPECTS 2nd CT, T= hours between 2 CT scans. Results: After reviewing 701 medical records from transferred patients, 51 patients with mean age 65±3 yrs and median initial NIHSS of 17 (IQR 14-21) were selected. In the multivariate analysis, good collateral status was independently associated with lower rates of ASPECTS decay measured by the relative rate of ASPECTS decay (0.04+/-0.01 score/h; p<0.05), the net ASPECTS difference (1.10+/-0.17 score/h, p<0.05) and the relative ASPECTS difference (0.12+/-0.02 score, p<0.05). The relative ASPECTS difference was most strongly associated with collateral status, and an independent predictor of good outcome (p=0.047) and final infarct volume (p=0.001) after controlling for age and NIHSS in a multivariate analysis. Conclusions: Good collateral circulation status is associated with lower rates of ASPECTS decay in transferred patients, which also tend to have smaller final infarct volumes and better clinical outcome after 3 months. The analysis of the collateral circulation gives us a better understanding of the pathophysiology in acute ischemic stroke.