Thrombus Migration Is A Common Phenomenon With Iv Tpa And May Have Negative Effects On Outcome When Tpa Treatment Is Given Before Endovascular Thrombectomy In Proximal Occlusions.

Introduction: There is interest in understanding thrombus dynamics from IV TPA prior to endovascular thrombectomy (EVT) given the possible dichotomy amongst sites of occlusion for IV TPA benefit/harm. Kaesmacher et al reported beneficial 5+% rates of early TICI > 2a reperfusion in distal M1 or M2 MCA occlusions with IV TPA. However in more proximal occlusions this was rare; and potentially harmful worsening of perfusion seen with change of occlusion site. We aimed to examine IV TPA related thrombus dynamics including migration further across both proximal and distal occlusions in a multicenter prospective cohort study INTERRSeCT. Methods: Acute ischemic stroke patients with intracranial occlusion who had baseline CTA and follow-up CTA or initial run angio in INTERRSeCT and IV TPA were reviewed. We evaluated change of occlusion site (COS) and classified patients into 4 categories: Complete Recanalization (CR) of primary occlusive lesion with no remaining thrombus; definite Thrombus Migration (dTM) with primary occlusion site moved to a distal artery and occlusion site patent on baseline CTA; probable Thrombus Migration (pTM) with COS evident but initial occlusion extent not visualized; or No Change of occlusion site (NC). Results: A total of 462 IV TPA patients were enrolled, 41% received EVT. Median time from TPA to follow-up imaging was 133 minutes. COS was seen in 50% of cases with CR in 15% and TM in 35% (dTM 12%, pTM 23%). Distal artery occlusion and longer interval of TPA to imaging were independent predictors for COS. In 62 proximal occlusion (ICA and proximal-mid M1 MCA) patients with follow-up imaging within 60 mins after TPA (receiving EVT in 94%), any TM showed a lower rate of 90-day mRS≤2 than NC (47% vs 78%, adjusted OR 0.21, 95%CI 0.04-0.87). No CR was seen in this early group. Conclusions: Thrombus migration is common after IV TPA. Thrombus instability from IV TPA may worsen clinical outcome in proximal occlusions despite early EVT initiation, possibly due to migration of thrombus to distal arteries accelerating infarction or more challenging thrombectomy due to thrombus dispersion. The benefit of IV TPA prior to EVT at comprehensive stroke centers for ICA or prox-mid M1 occlusions require more study in randomized clinical trials.