Thrombus Migration Paradox in Patients With Acute Ischemic Stroke

Background and Purpose- The location of the thrombus as observed on first digital subtraction angiography during endovascular treatment may differ from the initial observation on initial noninvasive imaging. We studied the incidence of thrombus dynamics, its impact on patient outcomes, and its association with intravenous thrombolytics. Methods- We included patients from the MR CLEAN registry (Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke) with an initial target occlusion on computed tomography angiography located in the intracranial internal carotid artery, M1, or M2. The conventional angiography target occlusion was defined during endovascular treatment. Thrombus dynamics were classified as growth, stability, migration, and resolution. The primary outcome was functional outcome at 90 days (modified Rankin Scale). The secondary outcomes were successful and complete reperfusion (extended treatment in cerebral infarction scores of 2b-3 and 3, respectively). Results- The analysis included 1349 patients. Thrombus migration occurred in 302 (22%) patients, thrombus growth in 87 (6%), and thrombus resolution in 39 (3%). Intravenous treatment with alteplase was associated with more thrombus migration (adjusted odds ratio, 2.01; CI, 1.29-3.11) and thrombus resolution (adjusted odds ratio, 1.85; CI, 1.22-2.80). Thrombus migration was associated with a lower chance of complete reperfusion (adjusted odds ratio, 0.57; CI, 0.42-0.78) and successful reperfusion (adjusted odds ratio, 0.74; CI, 0.55-0.99). In the subgroup of patients with M1 initial target occlusion, thrombus migration was associated with better functional outcome (adjusted common odds ratio, 1.49; CI, 1.02-2.17), and there was a trend towards better functional outcome in patients with thrombus resolution (adjusted common odds ratio, 2.23; CI, 0.93-5.37). Conclusions- In patients with acute ischemic stroke, thrombus location regularly changes between computed tomography angiography and digital subtraction angiography. Administration of intravenous alteplase increases the chance of thrombus migration and resolution. Thrombus migration is associated with better functional outcome but reduces the rate of complete reperfusion.