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DOI: 10.1055/a-2632-3100
Distinct Platelet Phenotype and Reactivity in Individuals with Permanent Atrial Fibrillation Treated with Direct Oral Anticoagulants: A Pilot Study
Funding The study was supported by Sapienza University Research Project 2023 (code: RG123188B4CD04C9) to L.S. and co-financed by the Next Generation EU (DM 1557 11.10.2022), in the context of the National Recovery and Resilience Plan, Investment PE8—Project Age-It: “Ageing Well in an Ageing Society.” The views and opinions expressed are only those of the authors and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. G.F.R. is supported by a grant issued by Sapienza University of Rome (AR22419077BB6154).

Abstract
Background
Atrial fibrillation (AF) is linked to an elevated risk of thromboembolic events. Despite the use of guideline-recommended direct anticoagulants (DOACs), a significant proportion of AF patients show a residual risk of thromboembolic events, driven by mechanisms that are not fully understood.
Objective
We conducted a pilot study to characterize the platelet function in DOACs-treated AF patients, to explore whether an association between platelets and the residual thromboembolic risk exists.
Methods
Within the Age-It project of the National Recovery and Resilience Plan, we examined by flow cytometry the platelet phenotype, reactivity, and mitochondrial function and quantified 12 inflammatory cytokines of individuals with DOACs-treated permanent AF without a history of stroke (n = 18, 66 ± 13 years, 39% females), compared with an age-, sex-, and comorbidity-matched control group without AF (n = 18, 65 ± 11 years, 39% females).
Results
Unstimulated circulating platelets of DOACs-treated AF displayed a low-adhesive phenotype compared with matched controls. Upon stimulation, platelets of DOACs-treated AF were hyporeactive to ADP and PAR1 stimulation, but hyper-reactive to GPVI stimulation (adjusted p < 0.01). The lower responsiveness to ADP correlated with increased plasmatic concentrations of IFN-γ (r = − 0.539; p < 0.05) and TNF-α (r = − 0.472; p < 0.05). The higher reactivity to GPVI associated with an increased mitochondrial function, which positively correlated with TNF-α levels.
Conclusion
Individuals with AF treated with DOACs exhibit low-grade inflammation and an altered platelet reactivity, suggesting a potential mechanism behind their residual thromboembolic risk. Further well-powered studies are warranted to test whether the observed platelet phenotype is implicated with the residual thromboembolic events in DOACs-treated AF patients.
Data Availability Statement
The data supporting the findings of this study are available upon request from the corresponding author.
Authors' Contribution
M.M. enrolled patients, analyzed and interpreted the data, and contributed to the final manuscript; F.M. performed experiments, analyzed and interpreted the data, and contributed to the final manuscript; A.S. and L.L. performed the experiments and analyzed the data; T.D., A.C, G.B., and M.P. enrolled the study participants, collected clinical data, and stratified the patients; M.P., G.F.R., R.C., S.B, and V.R. designed the study, recruited the patients, and critically revised the manuscript; L.S. coordinated the study, analyzed and interpreted the data, and wrote the manuscript.
* These authors contributed equally to this study.
Publikationsverlauf
Eingereicht: 27. Dezember 2024
Angenommen: 10. Juni 2025
Accepted Manuscript online:
11. Juni 2025
Artikel online veröffentlicht:
24. Juni 2025
© 2025. Thieme. All rights reserved.
Georg Thieme Verlag KG
Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany
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