Abstract W P43: Clot Characteristics on Ct-angiography Predict Early Recanalization With Intravenous Tpa in Patients With Acute Ischemic Stroke

Objective: We explore relationships amongst known and novel clot characteristics identified on CTA and early recanalization with IV tPA using classification and regression tree analysis (CART). Methods: Data is from patients presenting with acute ischemic stroke and proximal anterior circulation occlusions from the Calgary CTA database (2003-2012) and the Keimyung Stroke Registry (2005-2009). Patients who received IV t-PA followed by endovascular therapy were included. Clot location, clot length, residual flow through clot, ratio of contrast HU pre/post clot (cirHU) and distance of clot from M1 origin (for M1 MCA occlusions), were assessed on baseline CT-angio using OsiriX (Fig 1). Early recanalization (TICI 2a, 2b & 3) with IV t-PA was assessed on DSA first run. Results: We identified 228 patients (50.4% male, median age 69 yrs, median baseline NIHSS 17) who fulfilled inclusion criteria. Median symptom onset to IV t-PA time was 120 mins (IQR=70 mins) and median IV t-PA bolus to first angio run time was 70.5 mins (IQR=62 mins). Patients with residual flow within clot are five times more likely to recanalize than those without. Patients with residual flow within clot and a shorter clot length (≤15mm) were the most likely to recanalize(70.6%). Patients without residual flow with a carotid T/L occlusion rarely recanalized (1.7%). Patients without residual flow in M1 clots recanalized more if they were distal and had a cirHU < 2 (36.8%). (Fig 2). Inter-rater reliability for these clot characteristics was good to excellent. Conclusion: Clot characteristics on CTA could help physicians estimate early recanalization rates with IV tPA for proximal clots ranging from 0% to more than 80%.