In some patients with stable and unstable angina pectoris and in some donors without clinical manifestations of cardiovascular diseases and other pathologies, spontaneous platelet aggregation was completely suppressed by glycoprotein IIb-IIIa antagonists blocking the interaction of this glycoprotein with fibrinogen. Antibodies inhibiting binding of glycoprotein Ib with von Willebrand factor had no effect on the level and rate of spontaneous platelet aggregation. In the donor group, the level of spontaneous aggregation was almost 1.5-fold higher in persons with a certain genetic polymorphism (Leu-->Pro substitution in position 33 of glycoprotein IIIa). The level of spontaneous aggregation correlated with the amount of glycoprotein IIb-IIIa on the platelet surface (r = 0.41).

Measurement of platelet function by light transmission aggregometry (LTA) using a special device – an aggregometer requires significant time and is time-consuming. In this study, an automated LTA procedure was evaluated to establish the reference ranges. On the Sysmex CS-5100 analyzer, aggregation measurements were performed using several agonists at a certain concentration: ADP (2 µmol/L); arachidonic acid (1 mmol/L); collagen (2 µg/ml); ristocetin (1.2 mg/ml); epinephrine (5 µmol/L). For each agonist, the maximum and final aggregation, the Lag phase and the Area under the aggregation curve were measured. Reference ranges for a standard panel of activators were determined on 40 samples of healthy subjects in the concentrations recommended by the International Society on Thrombosis and Haemostasis. A standard panel of agonists can be used on Sysmex CS series analyzers: ADP, arachidonic acid; collagen; ristocetin, epinephrine, so these devices can replace specialized aggregometers or perform platelet aggregation where this investigation is not currently performed.

Introduction. The novel coronavirus infection COVID-19 (NCI COVID-19) caused by the COVID-19 virus, which occurs in the most severe forms, is accompanied not only by the development of respiratory failure and acute respiratory distress syndrome, but also by other equally dangerous complications such as covid-associated coagulopathy.The objective was to study the clinical and laboratory features of the development of endothelial dysfunction as the main component of covid-associated coagulopathy in the context of its most common manifestation – thrombotic events.Methods and materials. The medical records of 947 patients with confirmed novel coronavirus infection COVID-19 hospitalized at the Center for the Treatment of Patients with NCI COVID-19 of Pavlov University of the Ministry of Health of the Russian Federation during the so-called «2nd wave» of the pandemic from November 2020 to March 2021.Results. All thrombotic complications were detected only in patients with severe coronavirus infection (561 patients). Predisposing factors for the development of thrombosis in our patients were: advanced age, duration of hospitalization for more than 1 week, comorbidity in the form of coronary artery disease. Standard screening tests of the hemostasis system (platelet microscopy, coagulogram screening) do not reveal any significant features in the presence of thrombotic events, which requires the development of new studies to assess prothrombotic potential in patients with severe NCI COVID-19.Conclusion. The development of thrombotic events is one of the most formidable complications in the severe course of NCI COVID-19, which in turn leads to an increase in respiratory failure due to increased tissue hypoxia, and subsequently to death. The same patients have an increased risk of hemorrhagic events as a possible side effect of the therapy.

The purpose of this work was to study the features of the development of hemorrhagic complications in patients with bilateral viral pneumonia associated with COVID-19 of severe course, delivered to the hospital for emergency indications. The study included 561 patients with bilateral viral pneumonia. Various variants of bleeding were noted in 45 cases, all of them occurred in patients with severe new coronavirus infection (39 patients or 6.95% of all patients with severe NCI and 4.11% among all examined patients). Cases of combined hemorrhagic events were noted in 4 patients. In addition to age, gender, obesity and comorbidity, the use of antiplatelet therapy played a key role in the development of bleeding, which indicates the need to reduce the daily doses of such drugs at the later stages of treatment.

Introduction. COVID-associated coagulopathy is an important pathogenetic factor in the development of new coronavirus infection (NCI) complications. Therefore the use of anticoagulants is considered as one of the fundamental components of the therapy of NCI. The aim of the study was to find the optimal anticoagulant therapy regimen in patients with severe NCI. Materials and methods. The study is retrospective and included an analysis of 947 cases of confirmed NCI. A survival analysis was performed with the construction of Kaplan-Meyer curves in order to assess the effect of a particular anticoagulant therapy regimen on the occurrence of thrombosis, bleeding, and death. In order to exclude the influence of cofounders due to the retrospective nature of the study, the pseudorandomization method («propensity score matching») was used, followed by the re-construction of Kaplan-Meyer curves. Results. Among 947 patients with severe COVID-19, 27 thrombotic events were verified in 24 patients and 44 hemorrhagic incidents in 38 patients. The day of the event, regardless of the choice of the starting point (the onset of the disease or the 1st day of hospitalization) and its nature (thrombosis or bleeding), had no statistical differences (p=0.33 and p=0.12, respectively). The use of a particular anticoagulant therapy regimen did not significantly affect the development of thrombosis, bleeding or death, including the use of the propensity score matching method. Conclusion. Thus, using therapeutic doses of anticoagulants in COVID-19 patients does not give advantages over the use of preventive doses concerning the risk of thrombosis, bleeding and death.