Purpose The occurrence of thrombus migration (TM) in middle cerebral arteries (MCAs) prior to mechanical thrombectomy (MT) in patients suffering from acute ischemic strokes is a crucial aspect as TM is associated with lower rates of complete reperfusion and worse clinical outcomes. In this study, we sought to clarify whether histological thrombus composition influences TM. Methods We included 64 patients with acute MCA occlusions who had undergone MT. In 11 of the cases (17.2%) we identified TM prior to the interventions. The extracted clots were collected and histologically examined. The hematoxylin and eosin-stained specimens were quantitatively analyzed in terms of the relative fractions of the main constituents (red and white blood cells and fibrin/platelets). The histologic patterns were correlated with the occurrence of TM. Results Patients in whom TM could be observed were more often treated in a drip-and-ship fashion (90.9% vs 41.5%, p = 0.003). Stroke etiology did not differ between migrated and stable thrombi. A weak tendency for higher RBC and lower F/P content could be observed in thrombi that had migrated when compared with stable thrombi (RBC: median 41% vs 37%, p = 0.022 and F/P: median 54% vs 57%, p = 0.024). When using a cut-off of 60% RBC content for the definition of RBC-rich thrombi, a higher portion of RBC-rich thrombi could be identified in the migrated group as opposed to the stable group (36.4% vs 5.7%, p = 0.003). Conclusion Preinterventional TM may be influenced by the histological thrombus composition in a way that RBC-rich thrombi are more prone to migrate.
Keywords: Stroke; blood cells; histology; thrombus migration.