Atrial fibrillation and thrombosis: Immunohistochemical differences between in situ and embolized thrombi

W. E. Wysokinski, S. G. Owen, D. N. Fass, D. D. Patrzalek, L. Murphy, Robert D. McBane

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


Background/objective: Thromboembolism secondary to atrial fibrillation accounts for approximately one-fourth of all strokes. Although considerable resources have been targeted to pharmacologic prophylaxis, neither the cellular nor the biochemical composition of atrial thrombi is known. Quantitative immunohistochemistry was undertaken to define the composition of atrial thrombi and to explore morphological differences between atrial appendage thrombi and those that embolize. Patients/methods: Serial sections of thrombi obtained during valve replacement surgery or embolectomy from 22 patients with atrial fibrillation were stained with antibodies against fibrin, integrin β 3, or tissue factor and analyzed with NIH-image. Results: Thrombi showed distinct regions staining for either fibrin or platelets and on average, the fibrin-rich regions predominated (P < 0.0001). The platelet content of embolized thrombi was nearly twice that of atrial thrombi (P = 0.02). Non-staining amorphous material comprised nearly half of atrial thrombi in situ, but was rare in embolized thrombi (P < 0.001). Tissue factor colocalized to areas rich in platelets and granulocytes. Conclusions: The abundance of fibrin relative to platelets underscores the enhanced efficacy of warfarin prophylaxis in clinical trials. The finding of tissue factor localized to platelet-leukocyte clusters suggests its blood-borne origin. Compositional differences between in situ and embolized thrombi suggest directions for investigating propensity for embolization.

Original languageEnglish (US)
Pages (from-to)1637-1644
Number of pages8
JournalJournal of Thrombosis and Haemostasis
Issue number9
StatePublished - Sep 2004


  • Atrial fibrillation
  • Fibrin
  • Platelet
  • Thrombosis

ASJC Scopus subject areas

  • Hematology


Dive into the research topics of 'Atrial fibrillation and thrombosis: Immunohistochemical differences between in situ and embolized thrombi'. Together they form a unique fingerprint.

Cite this