Bridging Thrombolysis Before Endovascular Therapy in Stroke Patients With Faster Core Growth

Background and Objectives: It is still uncertain that going direct to endovascular thrombectomy (EVT) leads to equivalent outcomes as bridging intravenous thrombolysis (IVT) in acute ischemic patients. This study aimed to explore whether the rate of ischemic core growth influenced the patient outcomes after bridging IVT vs. direct EVT.

Methods: This was a retrospective cohort study based on the International Stroke Perfusion Imaging Registry (INSPIRE). It selected acute ischemic stroke patients receiving perfusion CT within 4.5 hours of stroke onset. Patients who went direct to EVT were compared to those who received bridging treatment of IVT prior to EVT. Ischemic core growth rate was estimated by the acute ischemic core volume on perfusion CT divided by the time from stroke onset to perfusion CT, based on the assumption of a linear growth pattern of ischemic core. Core growth rate was stratified into fast (>15 mL/hour) and slow (≤15mL/hour), based on its interaction with bridging IVT in predicting the primary outcome. The primary outcome was modified Rankin Scale of 0-2 at 3 months. Secondary outcomes included successful thrombectomy reperfusion defined by modified Thrombolysis in Cerebral Infarction score of 2b-3, and time from groin puncture to reperfusion.

Results: Of the 1221 EVT patients in INSPIRE, 323 patients were selected, of which 82 patients received direct EVT and 241 patients received bridging IVT. Bridging IVT was associated with a higher rate of good clinical outcome amongst patients with fast core growth (39% vs 7% for direct EVT, odds ratio=8.75 [1.96-39.1], p=0.005), but the difference was not significant for patients with slow core growth (55% vs 55% for direct EVT, odds ratio=1.00 [0.53-1.87], p=0.989). In patients with fast core growth, the bridging and direct EVT patients showed no difference in the reperfusion rate (80% vs. 76%, p=0.616). However, patients who received bridging IVT were more likely to achieve reperfusion earlier (the median groin to reperfusion time of 63.0 vs 94.0 minutes p=0.005).

Discussion: Patients with fast core growth were more likely to benefit from bridging intravenous thrombolysis. This is likely because prior intravenous thrombolysis facilitates clot removal and thus reduces time to reperfusion.