Abstract WMP92: Time Since Stroke Onset, Quantitative Collateral Score And Functional Outcome After Endovascular Treatment For Acute Ischemic Stroke - Results From The Mr Clean Registry.

Background: In patients with ischemic stroke undergoing endovascular treatment (EVT), time to treatment and collateral status are important prognostic factors. We assessed the relation between time to CT angiography (CTA) and collateral status. Furthermore, we assessed whether collateral status modifies the relationship between onset to recanalization time (ORT) and functional outcome. Methods: From the prospective, multicenter MR CLEAN Registry, we included patients with acute ischemic stroke, who had a carotid terminus or M1 occlusion and were treated with EVT in the Netherlands within 6.5 hours of symptom onset. A quantitative collateral score (qCS) was assessed from baseline CTA using an automated image analysis algorithm (Strokeviewer; Nico.lab). Multivariable regression models were used to assess the relationship between time to imaging and the qCS and between ORT and functional outcome (90-day modified Rankin Scale score). An interaction term (ORT * qCS) was introduced in the latter model to test whether qCS modifies this relation. Results: We analysed 1813 patients. The median time from symptom onset to CTA was 91 minutes [IQR: 56-150] and the median qCS was 49% [IQR: 25-79]. Longer time to CTA was not associated with qCS (β per 30 minutes, 0.001 [-0.008 - 0.010]). Both a higher qCS (acOR per 10% increase, 1.07 [1.03-1.10], p<0.001) and shorter ORT (acOR per 30 minutes, 1.17 [1.13-1.21], p<0.001) were independently associated with a shift towards better functional outcome. The qCS did not modify the relationship between ORT and functional outcome (p for interaction: 0.28; Figure). Conclusions: In patients with ischemic stroke caused by carotid-terminus or M1 occlusion presenting within 6.5 hours of symptom onset, the collateral status is unaffected by time to CTA and the benefit of a shorter ORT is similar across the entire range of collateral scores.