Altered profile of circulating microparticles in nonvalvular atrial fibrillation.

BACKGROUND:Nonvalvular atrial fibrillation (AF) is the most common cardiac arrhythmia, and it is associated with the prothrombotic state. Circulating microparticles (cMPs) are membrane vesicles that are shed from many cell types in response to cell activation and cell apoptosis. Several studies reported that cMPs may play a role in the hypercoagulable state that can be observed in patients with AF. The aim of this study was to determine the levels of total cMPs and characterize their cellular origins in AF patients. METHODS:Atotal of 66 AF patients and 33 healthy controls were enrolled. This study investigated total cMP levels and their cellular origin in AF patients using polychromatic flow cytometry. RESULTS:AF patients had significantly higher levels of total cMPs (median 36.38, interquartile range [IQR] 21.16-68.50 × 105 counts/mL vs median 15.21, IQR 9.91-30.86 × 105 counts/mL; P = 0.004), platelet-derived MPs (PMPs) (median 10.61, IQR 6.55-18.04 × 105 counts/mL vs median 7.83, IQR 4.44-10.26 × 10/mL; P = 0.009), and endothelial-derived MPs (EMPs CD31+ CD41-) (median 2.94, IQR 1.78-0.60 × 105 counts/mL vs median 1.16, IQR 0.71-2.30 × 105 counts/mL; P = 0.001) than healthy controls after adjusting for potential confounders. Phosphatidylserine positive MP (PS + MP) levels were similar compared between AF patients and healthy controls. CONCLUSION:The results of this study revealed a marked increase in total cMP levels, and evidence of elevated endothelial damage and platelet activation, as demonstrated by increased PMP and EMP levels, in AF patients. Additional study is needed to further elucidate the role of cMPs (PMPs and EMPs) in the pathophysiology of and the complications associated with AF.