Is There a Relationship Between the Histopathological Features and Anatomical Locations of Thrombi Obtained During Endovascular Thrombectomy in Acute Ischemic Stroke and Its Comorbid Diseases?

<b>Objective:</b> This study aimed to assess the association between the histopathological characteristics of thrombi extracted during endovascular thrombectomy and clinical factors, including the location of the occlusion, comorbid conditions, and treatment effectiveness, in patients with acute ischemic stroke. <b>Materials and Methods:</b> A total of 57 patients with acute ischemic stroke who underwent endovascular thrombectomy between 1 January 2022 and 31 December 2024 were included in the study. Thrombi were analyzed histopathologically and classified into categories based on their composition (RBC-dominant, fibrin-dominant, RBC = fibrin, organized fibrin) and phase (early or late stage). CD34 staining was used to assess organized fibrin. <b>Results:</b> The mean age of the patients was 65.2 ± 15.3 years, 52.6% were female, and 47.4% were male. The majority of thrombi were retrieved from the MCA M1 segment (64.9%). Histopathological analysis revealed that 49.1% of thrombi were RBC-dominant, 21.1% RBC = fibrin, 19.3% fibrin-dominant, and 10.5% contained organized fibrin. Early-stage thrombi accounted for 70.2% of cases, while late-stage thrombi comprised 29.8%. Thrombus composition was significantly associated with anatomical location, with RBC-dominant thrombi being most prevalent in the proximal ICA (88.2%; <i>p</i> < 0.001). CD34 staining identified organized fibrin in 10.5% of thrombi, exclusively in patients who underwent stent placement. However, no statistically significant correlation was identified between CD34 positivity and thrombus composition (<i>p</i> > 0.05). Additionally, no notable associations were found between thrombus composition and chronic comorbidities. <b>Conclusions:</b> Thrombus composition and stage exhibit variability depending on anatomical location, particularly in the proximal ICA, where RBC-dominant thrombi are more frequent. Although CD34 positivity indicates organized fibrin, it does not show a significant relationship with thrombus characteristics or patient comorbidities. These findings underscore the complex interplay between thrombus histopathology, anatomical location, and procedural outcomes, highlighting the need for further investigation.