Phosphatidylserine-exposing blood cells and microparticles induce procoagulant activity in non-valvular atrial fibrillation

Abstract Background The definitive role of phosphatidylserine (PS) in the prothrombotic state of non-valvular atrial fibrillation (NVAF) remains unclear. Our objectives were to study the PS exposure on blood cells and microparticles (MPs) in NVAF, and evaluate their procoagulant activity (PCA). Methods NVAF patients without ( n  = 60) and with left atrial thrombi ( n  = 18) and controls ( n  = 36) were included in our study. Exposed PS was analyzed with flow cytometry and confocal microscopy. PCA was evaluated using clotting time, factor Xa (FXa), thrombin and fibrin formation. Results PS + blood cells and MPs were significantly higher in NVAF patients without and with left atrial thrombi (both P + platelets, neutrophils, erythrocytes and MPs compared with patients without thrombi (all P + blood cells and MPs contributed to markedly shortened coagulation time and dramatically increased FXa/thrombin/fibrin (all P + platelets and MPs was positively correlated with thrombus diameter (all p Conclusions Our results suggest that exposed PS on blood cells and MPs play a procoagulant role in NVAF patients. Blockade of PS prior to thrombus formation might be a novel therapeutic approach in these patients.