Clot composition of embolic strokes of undetermined source: a feasibility study

BACKGROUND: A number of emerging studies have evaluated clot composition in acute ischemic stroke. Studies of clot composition of embolic strokes of undetermined strokes are lacking. OBJECTIVES: We sought to analyze the RBC to platelet ratios in clots and correlated our findings with stroke etiology. METHODS: This was a prospective study analyzing clots retrieved by mechanical thrombectomy in acute ischemic stroke patients at our institution. All clots were stained and 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 semi quantitative analysis of percentage RBC’s and platelets. Unpaired t-test was used to compare means of RBC to Platelet ratios. Correlation of RBC to Platelet ratios with stroke etiology was performed. RESULTS: A total of 33 clots from 33 patients were analyzed. Stroke etiology was undetermined in 6 patients, cardioembolic in 14, large vessel atherosclerosis (LVA) in 9, and carotid dissection in 4. The mean RBC to platelet ratio was 0.78:1 (+/− 0.65) in cardioembolic clots, 1.73:1 (+/− 2.38) in LVA and 1.4:1(+/− 0.70) in carotid dissections. Although patients with undetermined etiology had a similar clot composition to cardioembolic stroke (0.36:1+/− 0.33), (p = 0.19), it differed significantly from LVA and dissections respectively (p = 0.037, p = 0.01). CONCLUSION: In our study, a low RBC to Platelet ratio was found among patients with embolic strokes of undetermined source, however shared similar characteristics with cardioembolic thrombi. Ongoing collection and analysis is needed to confirm these findings and its significance in evaluating stroke etiology.