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

Abstract

Background and objectives: It is still uncertain that going direct to endovascular thrombectomy (EVT) leads to equivalent outcomes as bridging IV 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 with those who received bridging treatment of IVT before 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/h) and slow (≤15 mL/h), 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. The 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 1,221 EVT patients in the 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 among patients with fast core growth (39% vs 7% for direct EVT, odds ratio [OR] 8.75 [1.96-39.1], p = 0.005), but the difference was not notable for patients with slow core growth (55% vs 55% for direct EVT, OR 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 IVT. This is likely because prior IVT facilitates clot removal and thus reduces time to reperfusion.

Figure 1. Proportion of Good Clinical Outcome Across Core Growth Rates

The bridging EVT and direct EVT groups have similar 3-month outcome rate in patients with core growth ≤5 mL/h (56% vs 58%) or core growth of 5–15 mL/h (52% vs 50%); the bridging EVT group has higher rates of good outcome than the direct EVT group for a core growth rate of 15–25 mL (50% vs 10%) and a core growth rate >25 mL (35% vs 5%). EVT = endovascular thrombectomy; mRS = modified Rankin scale.

Figure 2. Interaction Plot of Core Growth Rate and Bridging EVT

(A) Predicting good clinical outcome. (B) Predicting final infarction volume. In patients with a fast core growth rate >15 mL/h, compared with the direct EVT group, the bridging EVT group shows a higher rate of good clinical outcome and smaller final infarction volume. EVT = endovascular thrombectomy; mRS = modified Rankin scale.

Figure 3. Distribution of 3-Month mRS Score Across Core Growth Groups

(A) Slow core growth ≤15 mL/h. (B) Fast core growth >15 mL/h. EVT = endovascular thrombectomy; mRS = modified Rankin scale.

Figure 4. Distribution of Time Parameters and Infarction Volumes Across Core Growth Groups

(A, C) Slow core growth ≤15 mL/h. (B, D) Fast core growth >15 mL/h. The bridging EVT group, compared with the direct EVT group, shows shorter time from groin puncture to reperfusion in both slow core growth patients (A) and fast core growth patients (B); however, only in patients with the fast core growth (D), the direct to EVT group show larger infarction growth volume; in patients with slow core growth (C), the bridging EVT group and the direct EVT group show no difference in the infarction growth volume. EVT = endovascular thrombectomy.