Initial studies investigating correlations between stroke etiology and clot composition
are conflicting and do not account for clot size as determined by area. Radiological
studies have shown that cardioembolic strokes are associated with shorter clot lengths
and lower clot burden than non-cardioembolic clots.To report the relationship between
stroke etiology, extracted clot area, and histological composition at each procedural
pass.As part of the multi-institutional RESTORE Registry, the Martius Scarlett Blue
stained histological composition and extracted clot area of 612 per-pass clots retrieved
from 441 patients during mechanical thrombectomy procedures were quantified. Correlations
with clinical and procedural details were investigated.Clot composition varied significantly
with procedural passes; clots retrieved in earlier passes had higher red blood cell
content (H4=11.644, p=0.020) and larger extracted clot area (H4=10.730, p=0.030).
Later passes were associated with significantly higher fibrin (H4=12.935, p=0.012)
and platelets/other (H4=15.977, p=0.003) content and smaller extracted clot area.
Large artery atherosclerotic (LAA) clots were significantly larger in the extracted
clot area and more red blood cell-rich than other etiologies in passes 1-3. Cardioembolic
and cryptogenic clots had similar histological composition and extracted clot area
across all procedural passes.LAA clots are larger and associated with a large red
blood cell-rich extracted clot area, suggesting soft thrombus material. Cardioembolic
clots are smaller in the extracted clot area, consistent in composition and area across
passes, and have higher fibrin and platelets/other content than LAA clots, making
them stiffer clots. The per-pass histological composition and extracted clot area
of cryptogenic clots are similar to those of cardioembolic clots, suggesting similar
formation mechanisms.
