PB1449 - The effect of therapy on the coagulation activity of microparticles in patients with polycythemia vera

Background: Polycythemia vera (PV) is characterized by thrombotic complications. It is known that a significant contribution to the development of prothrombogenic potential in patients with PV is made by the appearance of microparticles (MP) in the bloodstream, which appear as a result of intravascular activation of blood cells. MP expresses tissue factor (TF) and procoagulant phospholipids on their surface that can enhance prothrombogenic potential of blood plasma. Thus, unsafe and effective prevention of thromboembolic complications remains a major question in the management of these patients.

Aims: to estimate the coagulation activity of MP in patients with PV receiving the antiplatelet and combined therapy.

Methods: The study included 44 patients receiving the antiplatelet (n=22) and combined (antiplatelet+cytoreductive) therapy (n=22) and 30 healthy controls. Thrombin generation was measured in platelet-free plasma with Calibrated Automated Thrombinography. Following reagents were used: «FluCa kit», «PRP-reagent», containing rTF (1 pM), «MP-reagent», containing negatively charged phospholipids (4 µM), with CTI (40 µ/ml). Endogenous thrombin potential (ETP, nM*min) was evaluated. STATISTICA 12.0 was used. The results are given as median (Me) and Q1-Q3. Mann-Whitney test was used to compare the studied groups. P< 0.05 was considered statistically significant.

Results:

Results: The data are shown in the table.
PRP-reagent and MP-Reagent allow to estimate thrombin generation which depends on procoagulant phospholipids and TF, respectively. ETP (PRP-reagent) in patients receiving the antiplatelet therapy was significantly higher than in controls and tended to marked increase to the combined therapy patients (p < 0.076). ETP (MP-reagent) in all patients tended to increase compared to the control group (p < 0.4) but it wasn’t any differences between both groups.

Conclusion(s): Combined therapy in patients with PV leads to decrease of thrombin generation caused by phospholipids of MP. Used therapy has no effect on hemostatic potential, which determined by TF of MP in patients with PV.