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Updated: Nov 3, 2025
Catheter Ablation in Combination With Left Atrial Appendage Closure for Atrial Fibrillation
Published on: February 26, 2013
Large extracellular vesicles in the left atrial appendage in patients with atrial fibrillation-the missing link?
Andreas Zietzer1,2, Baravan Al-Kassou3, Paul Jamme3
1Medical Department II, University Hospital Bonn, Venusberg-Campus 1, 53127, Bonn, Germany. andreas.zietzer@ukbonn.de.
Insights
Permanent atrial fibrillation (AF) is linked to more platelet-derived large extracellular vesicles (lEVs) in the left atrial appendage. These lEVs may contribute to thrombus formation, increasing stroke risk.
Area of Science:
- Cardiovascular Medicine
- Hematology
- Molecular Biology
Background:
- Atrial fibrillation (AF) is a common arrhythmia linked to thrombus formation and stroke.
- Large extracellular vesicles (lEVs) can promote coagulation, with their origin influencing function.
- Understanding AF's impact on lEV subtypes is crucial for stroke prevention strategies.
Purpose of the Study:
- To investigate how different types of atrial fibrillation (AF) affect large extracellular vesicle (lEV) subtypes in specific atrial locations.
- To determine the association between AF, lEV levels, and potential pro-coagulant mechanisms.
Main Methods:
- Collected blood samples from the right atrium, left atrium, and left atrial appendage of 58 patients (permanent AF, non-permanent AF, no AF history).
- Utilized flow cytometry to analyze the origin of lEVs.
- Conducted in vitro studies on platelet activation and its effect on lEVs and endothelial cell migration.
Main Results:
- Permanent AF patients showed significantly higher proportions of platelet-derived lEVs in the left atrial appendage compared to non-permanent AF patients.
- Patients with atrial fibrillation (regardless of permanence) had elevated platelet-derived lEVs in the left atrial appendage.
- In vitro, activated platelet-derived lEVs (containing miR-222-3p and miR-223-3p) reduced endothelial cell migration.
Conclusions:
- Permanent AF is associated with increased platelet-derived lEVs in the left atrial appendage.
- These lEVs may play a role in the thrombus formation observed in the left atrial appendage during AF.
- Further research into lEVs could offer new therapeutic targets for AF-related stroke.
Abstract:
Atrial fibrillation (AF) is the most frequent arrhythmic disease in humans, which leads to thrombus formation in the left atrial appendage and stroke through peripheral embolization. Depending on their origin, large extracellular vesicles (lEVs) can exert pro-coagulant functions. In the present study, we investigated how different types of AF influence the levels of large EV subtypes in three distinct atrial localizations. Blood samples were collected from the right and left atrium and the left atrial appendage of 58 patients. 49% of the patients had permanent AF, 34% had non-permanent AF, and 17% had no history of AF. Flow cytometric analysis of the origin of the lEVs showed that the proportion of platelet-derived lEVs in the left atrial appendage was significantly higher in permanent AF patients compared to non-permanent AF. When we grouped patients according to their current heart rhythm, we also detected significantly higher levels of platelet-derived lEVs in the left atrial appendage (LAA) in patients with atrial fibrillation. In vitro studies revealed, that platelet activation with lipopolysaccharide (LPS) leads to higher levels of miR-222-3p and miR-223-3p in platelet-derived lEVs. Treatment with lEVs from LPS- or thrombin-activated platelets reduces the migration of endothelial cells in vitro. These results suggest that permanent atrial fibrillation is associated with increased levels of platelet-derived lEVs in the LAA, which are potentially involved in LAA thrombus formation.
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