[Peculiarities of hemostasis in patients with COVID-19].

AIM: Analysis of the dynamics of different stages of clot formation and its lysis in patients with different COVID-19 severity. MATERIALS AND METHODS: We prospectively included 58 patients with COVID-19 (39 patients with moderate disease severity and 18 patients with severe disease) and 47 healthy volunteers as a control group. All participants underwent the assessment of flow-mediated dilation (FMD) of brachial artery, impedance aggregometry, rotational thromboelastometry and thrombodynamics. Von Willebrand factor antigen (vWF:Ag) quantification was also performed in patients with COVID-19. Measurements were repeated on the 3rd and 9th day of hospitalization. RESULTS: Compared to the control group, patients with COVID-19 showed reduced values of platelet aggregation and greater values of the clot growth rate, as well as its size and density. On the first day of hospitalization, we found no differences in the activity of plasma hemostasis and endogenous fibrinolysis between subgroups of patients. With the progression of the disease, the growth rate and size of the clot were higher in the severe subgroup, even despite higher doses of anticoagulants in this subgroup. An increase in platelet aggregation was noted during the progression of the disease, especially in the severe subgroup. There were no differences in the results of the FMD test by subgroups of patients. The vWF:Ag level was significantly higher in the severe subgroup. CONCLUSION: Thus, plasma hemostasis followed by secondary platelet activation correlates with the severity of COVID-19. Patients with moderate to severe coronavirus infection have predominantly local rather than generalized endothelial dysfunction.

The state of platelet and plasma hemostasis as a predictor of coronary blood flow in patients with acute myocardial infarction.

Aim      To study the relationship of the platelet function and plasma homeostasis with the blood flow in the infarct-related artery (IRA) and with the course of acute myocardial infarction (AMI).Material and methods  This study included 93 patients with AMI (75 patients with ST-elevation AMI and 18 patients without ST segment elevation). 63 patients had TIMI 0-1 blood flow in the IRA and 30 patients had TIMI 2-3. Rotational thromboelastometry, impedance aggregometry, the endothelium-dependent vasodilation (EDVD) test, and the thrombodynamics test were performed for all patients. The primary clinical endpoint included the totality of in-hospital complications of AMI, and the secondary endpoint included the totality of out-of-hospital complications of AMI. Major bleedings (BARC 3-5) and minor bleedings (BARC 1-2) were evaluated separately.Results Patients with IRA TIMI 0-1 flow were characterized by a shorter blood clotting time (BCT), larger thrombus size and density, more intense platelet aggregation induced by arachidonic acid and ADP, and lower values of the EDVD test. It was found that the parameters of platelet aggregation induced by arachidonic acid (AUC Asa) in combination with BCT allowed assessment of the severity of IRA blood flow disorder (sensitivity 76 %, specificity 71 %) in patients with AMI, regardless of the presence of ST segment elevation on the ECG. In addition, the incidence of the primary endpoint was greater in patients with IRA TIMI 0-1 flow (41.3% and 16.7%, respectively; p=0.015). In patients with TIMI 2-3 flow in the long-term period of the disease, the incidence of minor bleedings was significantly higher (8.5% and 30.4 %, respectively; p=0.045).Conclusion      Compared to patients with preserved blood flow, patients with AMI and IRA TIMI 0-1 flow are characterized by endothelial dysfunction and more intense processes of thrombogenesis and platelet aggregation. It has been shown for the first time that the combination of two simple criteria for assessing hemostasis (AUC Asa; BCT) allows assessment of the degree of IRA blood flow disorder in patients with AMI.