Key result
Mitral regurgitation exerts antithrombotic effects despite AF, reducing vWF activity by ~31%.
Why the study?
In nonrheumatic AF, the effect of mitral valve regurgitation on left atrial thrombotic risk remains controversial, and the thrombotic effect of lone AF without atrial myopathy is not well studied.
Does severe mitral valve regurgitation vs. lone atrial fibrillation alter left atrial thrombotic risk markers in a porcine model?
RCT (n=20)
Randomized (14:6 allocation to severe MR vs sham)
Does severe mitral valve regurgitation vs. lone atrial fibrillation alter left atrial thrombotic risk markers in a porcine model?
In a porcine model, severe mitral regurgitation exerts an antithrombotic effect in the left atrium despite inducing significant atrial myopathy, whereas lone atrial fibrillation without underlying myopathy exerts a prothrombotic effect.
May signal antithrombotic effects in mitral regurgitation; leaves open relevance to human thrombotic risk models.
Background/Introduction Atrial fibrillation (AF) and its underlying atrial myopathy increase the left atrial thrombotic risk, as calculated by the CHA2DS2-VA score, which correlates well with the presence of atrial myopathy. However, the risk prediction of this score is modest (C-statistic=0.6). Other factors, such as mitral valve regurgitation (MR), may influence thrombotic risk. In nonrheumatic AF, the effect of MR on left atrial thrombotic risk remains controversial. Furthermore, the thrombotic effect of AF itself, without atrial myopathy, is not well studied. Purpose To assess the effect of MR (high flow) and lone AF (low flow) on left atrial thrombotic risk. Methods A total of 20 Piétrain pigs (with equal sex distribution) were randomized to severe MR, induced by selective cutting of the chordae tendineae (n=14), or the sham procedure (n=6). High-frequency atrial tachypacing was performed to induce paroxysmal AF (15 min.). Left atrial blood samples were collected before and after AF-induction. After four weeks, blood sampling was repeated in all pigs, and the sham group underwent a longer AF-tachypacing session (60 min.). To explore left atrial thrombotic risk, platelet aggregation, intrinsic, extrinsic, and common coagulation pathways, fibrinolysis, and von Willebrand factor (vWF) assays were measured. Results Echocardiography showed MR severity grade 3.5-4/4 in all pigs of the intervention group. Severe MR led to left atrial dilation, with a greater increase in mean left atrial volume compared to the sham group (+28.1 ± 5.4 ml vs. +6.7 ± 2.1 ml; p=0.01), and more left atrial fibrosis (25.8 ± 5.2% vs. 13.0 ± 2.9%; p<0.001). There was a significantly divergent effect of MR vs. AF on left atrial thrombotic risk (P-values for all interactions <0.05, Figure 1). MR was associated with increases in mean platelet volume (MPV, +9.1%), APTT (+9.6%), PT (+8.5%), and D-dimers (+54.0%), and decreases in platelet aggregation (-9.7%), fibrinogen (-23.1%), and vWF antigen (-18.1%) and activity (-31.1%), indicating an antithrombotic effect. The opposite effect was observed for AF, with decreases in MPV (-2.2%), APTT (-1.1%), and PT (-1.9%), and increases in platelet aggregation (+1.4%), fibrinogen (+2.2%), and vWF antigen (+3.4%) and activity (+4.1%), indicating a prothrombotic effect. Conclusion Our data show a prothrombotic effect of lone AF and an antithrombotic effect of MR on left atrial thrombotic risk. The antithrombotic effect of MR was observed despite the development of significant atrial myopathy. This implies that MR could be a modifying protective factor in thrombotic risk assessment of AF patients and could help individualize anticoagulant treatment. The data of our AF model, without underlying atrial myopathy, emphasizes the importance of rhythm control in AF patients to minimize left atrial thrombogenicity and challenges safety of withholding anticoagulation in patients with low CHA2DS2-VA scores and persistent AF.
No takes yet. Share an insight, caveat, or question.
Laer et al. (2026) conducted an RCT in Severe mitral valve regurgitation and paroxysmal atrial fibrillation (porcine model) (n=20). Severe mitral regurgitation induction (chordae tendineae cutting) and high-frequency atrial tachypacing vs. Sham procedure with atrial tachypacing was evaluated on Left atrial thrombotic risk markers (platelet aggregation, coagulation pathways, fibrinolysis, and von Willebrand factor assays) (p=<0.05). Mitral regurgitation exerted an antithrombotic effect (platelet aggregation -9.7%, vWF activity -31.1%) while lone AF was prothrombotic (+1.4%, +4.1%; interaction P<0.05).
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: