Background: While more endovascular treatments for acute stroke are being performed, few studies evaluate clot composition with variable results. We sought to evaluate the feasibility of collecting and analyzing the RBC to platelet ratios in clots, and correlated our findings with stroke etiology.
Methods: This is an ongoing prospective study analyzing clots retrieved by mechanical thrombectomy in acute stroke patients at our institution. Retrieved clot material was fixed and cut at 4-m thickness. All clots were stained with hematoxylin-eosin to identify red blood cells (RBC’s), and antibodies for platelet glycoprotein IIIa with CD61 (LifeSpan Biosciences, Seattle, Washington) for platelets. Stained slides were scanned at 200x magnification by using a Scanscope XT digital scanner (Apergio, Vista, California). Image-J software (National Institutes of Health, Bethesda, Maryland) was used for semiquantitative analysis of percentage RBC’s and platelets. Correlation of RBC to Platelet ratios with stroke etiology was performed.
Results: A total of 18 clots from 18 patients were analyzed. Stroke etiology was cardioembolic in 8, Large vessel atherosclerosis (LVA) in 5, undetermined in 3 and carotid dissection in 2. The mean RBC to platelet ratio was 0.51:1 in cardioembolic and 0.64:1 in LVA strokes. Patients with undetermined etiology had similar clot composition (0.53:1) to cardioembolic stroke. The highest RBC content was found in carotid dissection thrombus with a ratio of 1.73:1 as compared to other etiologies (p=0.01 cardioembolic, p=0.04 undetermined, p=0.02 LVA).
Conclusion: In our study’s first phase, clot processing and analysis was found to be feasible. Although a high mean RBC content was found in carotid dissections and strokes of undetermined etiology had similar clot composition to cardioembolic stroke, ongoing collection and analysis will help support these findings.