Dissimilarity of increased phosphatidylserine-positive microparticles and associated coagulation activation in acute coronary syndromes

Objective We evaluated cellular origin, numbers, and procoagulant activity of phosphatidylserine-positive microparticles (MPs) among subgroups in acute coronary syndromes (ACS). Materials and methods Parameters were measured on admission, days 1 (within 24 h of admission), 2, 3, and 7. All ST-elevated myocardial infarction (STEMI) patients presented more than 3 h from symptom onset and received fibrinolysis treatment; controls included unstable angina and non-STEMI patients as well as healthy controls. Phosphatidylserine-positive MPs were detected by flow cytometry, whereas procoagulant activity was assessed by coagulation time, purified coagulation complex assays, and fibrin formation. MP-induced fibrins were visualized by confocal microscopy. Results On admission, the total MP count was similar to 2.5-fold higher in the ACS groups compared with the healthy controls (P<0.05), primarily originating from platelets and endothelial cells, and there were no significant differences among ACS subgroups. Specifically, leukocyte-derived and erythrocyte-derived MPs were higher in the STEMI group compared with unstable angina and non-STEMI groups (both P<0.05). Further, MPs from the ACS groups reduced coagulation time by 27.5% and induced intrinsic and extrinsic FXase, prothrombinase, and fibrin formation by 2.8-, 2.3-, 2.5-, and 1.7-fold, respectively (P<0.05 for all), whereas blocking phosphatidylserine with lactadherin inhibited similar to 70% of procoagulant activity. MP number and concomitant coagulation decreased significantly by day 2 and continued to decrease gradually during the recovery period. Conclusion This study shows that MP characteristics from circulating blood may be used as prognostic indicators to reflect the origin cell of activation and thrombophilic states found in ACS subgroups. Coron Artery Dis 27:365-375 Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.