anti-Xa Activity Research Articles

Bleeding outcomes in critically ill patients on heparin with discordant aPTT and anti-Xa activity.

Activated partial thromboplastin time (aPTT) and unfractionated heparin (UFH) level via the anti-factor Xa activity assay (anti-Xa) are commonly used assays for UFH monitoring. While discordance between the two assays is common, its impact on critically ill patient outcomes is unclear. This study aimed to compare the incidence of major bleeding events among critically ill patients with discordant aPTT and anti-Xa activity while on UFH, to patients with no discordance. This was a single-center, retrospective cohort study of critically ill adult patients who had simultaneous anti-Xa and aPTT levels while receiving continuous UFH infusion. The primary outcome was the incidence of a major bleeding event up to 24h after UFH discontinuation. Secondary outcomes included incidence of 30-day thrombosis and hospital length of stay (LOS). Among 264 included patients, 156 patients (59%) had at least one discordant paired level. Patients with discordance had an increased risk of major bleeding events (14% versus 5%; unadjusted risk ratio, 3.0; 95% CI 1.2-7.8; p = 0.01), and increased risk of thrombotic events (4% versus 0%; p = 0.04). Hospital LOS was similar between the two groups (13.8 days versus 11.4 days; p = 0.08). In this cohort of critically ill patients receiving continuous UFH, discordance in aPTT and anti-Xa activity was frequently observed and was associated with an increased risk of major bleeding events. While both assays remain viable monitoring options, evaluating simultaneous levels may aid in the management of critically ill patients. In patients with discordance, an individualized approach balancing bleeding and thrombotic risks should be considered.

Intravenous enoxaparin guided by anti-Xa in venovenous extracorporeal membrane oxygenation: A retrospective, single-center study.

Unfractionated heparin is used as the most common anticoagulation for venovenous extracorporeal membrane oxygenation (VV ECMO) patients. However, it is accompanied by frequent bleeding and thrombotic complications. The aim of the study was to demonstrate the feasibility of Enoxaparin anticoagulation for VV ECMO patients. This study is a retrospective analysis of VV ECMO patients on continuous intravenous Enoxaparin anticoagulation. The primary outcome was the incidence of bleeding, thrombotic, and neurological complications during ECMO support. The secondary outcome was an analysis of secondary and primary hemostasis profiles. Data from 38 patients were analyzed in this study. The incidence of bleeding complications was 5.3%, for thrombotic complications it was 2.6% and for neurological (bleeding/ischemic events) complications it was 10.5%. The targeted anti-Xa activity of 0.4-0.6 IU/mL was achieved and maintained during whole ECMO period in 28 patients (73.8%), not affecting the hemocoagulation profile represented by APTT-r 1.15 ± 0.2, TT 18.67 ± 3.35 s, PT/INR 1.21 ± 0.19, fibrinogen 5.39 ± 1.49 g/L, antithrombin, and platelet count. Primary hemostasis pathology was diagnosed in all patients by PFA 200 tests Col/EPI 279 ± 38 s and Col/ADP 249 ± 66 s. The running time of ECMO was 7.8 ± 3.4 days. Enoxaparin anticoagulation appears to be feasible for VV ECMO patients without an increase in adverse events. Further larger-sampled and comparative studies are needed in the future to support our findings.

Periovulatory anticoagulant therapy enhances embryo recovery rates in superovulated mares

Although protocols for superovulation have been described in horses, this technique has been discouraged due to the low embryo recovery rates in superovulated mares. The reason for these poor results is poorly understood, but the formation of a blood clot in the ovulation fossa following ovulations has been hypothesized. Therefore, this study aimed to assess the safety and effect of periovulatory anticoagulant therapy on embryo recovery of superovulated mares. In experiment 1, five mares were assigned to receive five anticoagulant treatments in a crossover design: intravenous injections of 150 (H1), 300 (H2), 400 (H3), 450 (H4), 600 (H5) IU/kg of unfractionated heparin (UFH, heparin sodium); and had blood samples sequentially collected for up to 48 h post-treatment to test Prothrombin (PT) and activated partial thromboplastin time (aPTT). In experiment 2, four mares were treated in a crossover design with intravenous injection of 450 IU/kg of UFH and 1 mg/kg of low molecular weight heparin (LMWH, enoxaparin) and had blood collected as previously for analysis of plasma anti-Xa activity. In experiment 3, eleven mares had four cycles randomly assigned to four groups. In the control group, mares did not receive any treatment. In contrast, in groups G1, G2, and G3, mares were superovulated with equine pituitary extract and treated 34 h after the induction of ovulation with a placebo (NaCl 0.9%, G1), 450 IU/kg of UFH (G2), or 1 mg/kg of LMWH. Mares in all groups had ovulation induced with hCG plus histrelin acetate and were bred with fresh semen from one stallion. Embryo flushing was performed nine days post-ovulation. In experiment 1, only mares in groups H4 and H5 had increased aPTT and PT for up to 12 h, and in all groups, aPTT and PT values returned to baselines at 24 h post-treatment. In experiment 2, plasma anti-Xa activity was increased by both therapies for up to 12 h after treatment and was at baseline levels 24 h post-treatment. In experiment 3, periovulatory therapy with anticoagulants increased embryo recovery rates per cycle (G2, 250%; G3, 260%) compared to control-assigned cycles (60%; P<0.05), whereas G1-assigned cycles (160%) had intermediate embryo recovery. In conclusion, periovulatory anticoagulant therapies may be an alternative to improve embryo recovery in superovulated mares.

Safety and efficacy of apixaban versus warfarin in peritoneal dialysis patients with non-valvular atrial fibrillation: protocol for a prospective, randomised, open-label, blinded endpoint trial (APIDP2)

IntroductionSeveral randomised controlled trials have demonstrated that novel oral anticoagulants are safer compared with vitamin K antagonists for the management of non-valvular atrial fibrillation (NVAF) to prevent thromboembolic events in...

A retrospective study of the management and outcomes of pregnancies with inherited antithrombin deficiency.

Antithrombin (AT) deficiency is a rare but highly thrombogenic inherited thrombophilia. Its association with adverse pregnancy outcomes (APO) is undefined. There is limited guidance on managing AT deficiency in pregnancy. Some significant issues remain controversial, including risk assessment for prophylactic anticoagulation, anticoagulant therapy, and monitoring. Our goal was to examine if the antepartum management of patients with AT deficiency affected their pregnancy outcomes. This retrospective, single-center observational study included pregnant women with inherited AT deficiency in Peking Union Medical College Hospital between 2013 and 2024. Seventeen pregnancies in 6 women with AT deficiency were identified. A total of 7 pregnancies received adjusted-dose low-molecular-weight heparin (LMWH) and were monitored by anti-Xa level, AT activity, and D-dimer. There were 5 live births (all received LMWH), 7 second-trimester abortions (1 received LMWH), and 5 early pregnancy losses (1 received LMWH). There were 5 abruptio placentae events (3 received LMWH) and 7 thrombotic events (2 received LMWH). AT deficiency is at least an important partial factor contributing to APO. It is suggested to make a full assessment of AT patients both for venous thrombus embolism and APO risk. We observed a high prevalence of heparin resistance and a positive correlation between adequate anticoagulation and pregnancy outcome based on tight monitoring with anti-Xa level and timely adjustment of the LMWH dosage.

Anti-Xa Activity Test Is Needed but Is Not Enough for Monitoring Fondaparinux Therapy Among Critically Ill Patients.

Fondaparinux monitoring is not required among noncritically ill patients due to a predictable dose-response effect. However, this is debatable among critically ill patients, because fondaparinux bioavailability can be influenced by complicated medical conditions. To investigate fondaparinux monitoring among the critically ill. Retrospective analysis of patients admitted in intensive care unit from February 2021 to December 2021, who received prophylactic fondaparinux and had anti-Xa activity tests. Of 156 anti-Xa values, 86 (55.1%) were within 0.10-0.50 μg/mL (the recommended prophylactic range), 38 (24.4%) were less than 0.10 μg/mL, 32 (20.5%) were greater than 0.50 μg/mL, demonstrating an unpredictable dose-response effect. Among 70 patients, thrombotic tendency was controlled in 32 (45.7%), thrombosis progressed in 22 (31.4%), bleeding events occurred in 16 (22.9%). Patients with progressed thrombosis had 17 of 54 (31.5%) anti-Xa less than 0.10 μg/mL, even though this proportion was greater than that of patients with controlled thrombotic tendency (11 of 72, 15.3%), it was similar to that of patients with bleeding (10 of 30, 33.3%), indicating a weak practicability of anti-Xa for monitoring fondaparinux efficacy. Thrombin-antithrombin complex showed a gradual decline among patients with controlled thrombotic tendency, but a bounce-back effect among patients with progressed thrombosis. Thrombelastography R value above the upper reference value occurred more frequently among patients with bleeding (4 of 6, 66.7%) compared to patients without bleeding (4 of 22, 18.2%) (P = .01). The fondaparinux dose-response effect was unpredictable among the critically ill; anti-Xa activity combined with thrombin-antithrombin complex and thrombelastography can be helpful to guide a precise fondaparinux therapy in this population.

Pleiotropic Effects of Heparin and its Monitoring in the Clinical Practice.

Unfractionated heparin (UFH) was uncovered in 1916, has been used as an anticoagulant since 1935, and has been listed in the World Health Organization's Model List of Essential Medicines. Despite the availability of many other anticoagulants, the use of heparin (either low molecular weight heparin [LMWH] or UFH) is still substantial. Heparin has pleotropic effects including anticoagulant and several nonanticoagulant properties such as antiproliferative, anti-inflammatory activity, and anticomplement effects. Although UFH has been widely replaced by LMWH, UFH is still the preferred anticoagulant of choice for patients undergoing cardiopulmonary bypass surgery, extracorporeal membrane oxygenation, and patients with high-risk mechanical cardiac valves requiring temporary bridging with a parenteral anticoagulant. UFH is a highly negatively charged molecule and binds many positively charged molecules, hence has unpredictable pharmacokinetics, and variable anticoagulant effect on an individual patient basis. Therefore, anticoagulant effects of UFH may not be proportional to the dose of UFH given to any individual patient. In this review, we discuss the anticoagulant and nonanticoagulant activities of UFH, differences between UFH and LMWH, when to use UFH, different methods of monitoring the anticoagulant effects of UFH (including activated partial thromboplastin time, heparin anti-Xa activity level, and activated clotting time), while discussing pros and cons related to each method and comparison of clinical outcomes in patients treated with UFH monitored with different methods based on available evidence.

Анти-Ха активность у пациентов с неклапанной фибрилляцией предсердий на фоне приема апиксабана и ривароксабана

Direct oral anticoagulants (DOAC) are widely used for prevention of stroke in patients with atrial fibrillation. The need for therapeutic drug monitoring of DOACs remains unclear. Measurement of anti-Xa activity that directly correlates with serum drug concentration seems to be a promising approach for monitoring of Xa inhibitors.

Glass bead-activated clotting time (gb-ACT) for monitoring the anticoagulation effects in elderly patients with high risk of venous thromboembolism (VTE)

ABSTRACT Background To find a new bedside method to monitor the anticoagulation effects of low-molecular-weight heparins (LMWHs) in patients with a high risk of venous thromboembolism (VTE). Research design and methods A total of 32 hospitalized patients (aged ≥60 years) who were at high risk of VTE were assigned to receive subcutaneous LMWH for 5 to 14 days. Plasma anti-factor Xa (anti-Xa) activity was conducted by a chromogenic method, and the glass bead-activated whole blood clotting time (gb-ACT) value was obtained by a Sonoclot Analyzer. Results A correlation between the gb-ACT values and the anti-Xa levels was suggested (R = 0.447, p = 0.002), and it was stronger in the older group aged 80 years above (R = 0.467, p = 0.008) and in the group of patients with an eGFR of 30 ~ 60 mL/min (R = 0.565, p = 0.005). The area under the curve (AUC) for gb-ACT by receiver operating characteristic (ROC) curve evaluation was 0.725 (p = 0.011), and the gb-ACT >282.5s provided a sensitivity of 60% and specificity of 74% for anti-Xa >0.800 IU/ml. Conclusions The gb-ACT values detected by a Sonoclot Analyzer could act as a novel bedside method in the monitoring of LMWH anticoagulation.

Primary prevention of venous thromboembolism with low molecular weight heparins in surgical patients – 2024: Council of Experts resolution

On March 15, 2024, in Moscow, the Russian Phlebological Association and the National Association of Specialists in Thrombosis, Clinical Hemostasiology and Hemorheology organized a meeting of the Council of Experts during the Russian Forum on Thrombosis and Hemostasis on the acute issues of venous thromboembolism (VTE) primary prevention using low molecular weight heparins (LMWH) in surgical patients with different body weight. The participants reviewed the relevance and prevalence of this problem in surgical practice, discussed risk factors and the frequency of VTE development, including bleeding in the postoperative period, and the Caprini risk score for complications. The discussion also focused on standard and personalized LMWH doses for primary prophylaxis of VTE in the perioperative period in surgical patients, depending on body weight, and the role of laboratory tests, including assessment of LMWH anti-Xa activity for monitoring the efficacy and safety of VTE primary prevention in clinical practice.

Comparison of thrombodynamic tests with determination of anti-Xa activity in evaluation of the efficacy of anticoagulant therapy in patients suffering deep vein thrombosis of the lower extremities

Deep vein thrombosis of the lower extremities remains an important medical and social problem in practical medicine. Currently, a weight-dependent low-molecular-weight heparin dosing approach is used to treat deep vein thrombosis of the lower extremities in wounded patients without regard to the state of the hemostasis system. This observational study included 30 patients with deep vein thrombosis of the lower extremities who were hospitalized for examination and treatment at the Kirov Military Medical Academy. During treatment with enoxaparin sodium at therapeutic doses, depending on body weight, the parameters of the thrombodynamics test were assessed in all patients, and antiXa activity was determined at the peak of the drug (after 3–4 h) and at the end (before the next injection) of its action. A strong inverse correlation was established between the growth rate indicator of the thrombodynamics test clot and antiXa activity at the peak (–0.777; p 0.05) and at the end (–0.715; p 0.05) of the action of sodium enoxaparin. The standard dose of anticoagulant drug, depending on body weight, revealed that 30% of patients were in the hypercoagulation zone, not reaching the target values of the thrombodynamic clot growth rate and anti-Xa activity. The thrombodynamics test results identified the growth rate of the test clot with antiXa activity, which allows both methods to be considered comparable for laboratory monitoring low-molecular-weight heparin therapy in wounded individuals. The insufficient anticoagulant effect in one-third of the injured individuals that received the standard and therapeutic doses of low-molecular-weight heparins requires the development of a personalized approach to titration of low-molecular-weight heparins, which may be based not on the concentration of the drug per body weight but on the achieved anticoagulant effect that optimizes the treatment outcomes and patient prognosis. Accordingly, further research is required.

Cell Salvage Using the Autotransfusion Device CATSmart®: A Randomized Controlled Bicentric Trial Evaluating the Quality of Two New Flex Wash Programs

Background: The use of cell salvage and autologous blood transfusion is an important and widespread method of blood conservation during surgeries with expected high blood loss. The continuous autotransfusion device CATSmart^® (Fresenius Kabi, Germany) contains two new washing programs on the device called Flex wash 3 and Flex wash 5. To the best of our knowledge, there are no published clinical data regarding the performance of the two new washing programs. Methods: In total, 69 patients undergoing cardiac or orthopedic surgery were included in this randomized, controlled, bicentric trial to validate the red cell separation process and washout quality of Flex wash 3 compared to Flex wash 5. After washing, the primary quality target was to determine hematocrit value, recovery rate, albumin, and total protein elimination rate in the packed red cells (PRCs). The secondary objective was to assess the elimination of heparin by measuring the factor anti-Xa activity by a 1- and 2-stage assay in PRC after washing. Results: In the whole cohort of patients, hematocrit was 16.00% [9.15%; 21.30%] (median [Q1; Q3]) in the wound blood and 69.90% [51.10%; 80.90%] in the PRC resulting in a recovery rate of 63.92% [47.06%; 88.13%]. The albumin elimination rate was 98.77% [97.94%; 99.27%], and the total protein elimination rate was 98.85% [97.76%; 99.42%]. The heparin elimination rate was 99.95% [99.90%; 99.97%] in the 1-stage assay and 99.70% [99.41%; 99.87%] in the 2-stage assay. There was no difference between Flex wash 3 and Flex wash 5 washing procedure regarding the recovery rate 63.75% [46.64%; 78.65%] versus 67.89% [47.20%; 92.69%] (p = 0.85), albumin elimination rate 98.74% [97.67%; 99.27%] versus 98.78% [98.10%; 99.28%] (p = 0.97), protein elimination rate 98.79% [97.94%; 99.47%] versus 98.92% [97.58%; 99.42%] (p = 0.88), and anti-Xa elimination rate in the 1-stage assay 99.94% [99.79%; 99.97%] versus 99.95% [99.92%; 99.97%] (p = 0.24) and in 2-stage assay 99.66% [99.20%; 99.86%] versus 99.77% [99.47%; 99.90%] (p = 0.23). Conclusions: The two new washing procedures, Flex wash 3 and Flex wash 5, enable sufficient and comparable red cell separation and washout quality of albumin, total protein, as well as heparin.

Interference of oral anti-Xa anticoagulants during monitoring of unfractionated heparin treatments: practical and future attitudes

Contrary to direct oral anticoagulants (DOAC), unfractionated heparin (UFH) requires daily monitoring when administered at therapeutic dose. At present, UFH monitoring is preferably carried out by measuring plasma anti-Xa activity, however, in patients previously treated with an anti-Xa DOAC and switched to UFH, there is a high risk of DOAC interfering with the measurement of UFH anti-Xa activity. Residual anti-Xa DOAC in the sample can lead to an overestimation of the anticoagulant activity attributed to heparin and thus to incorrect anticoagulation. This risk of interference should not be overlooked because interference may occur even at concentration of DOAC below the hemostatic safety threshold and can last several days. To overcome this issue, several alternatives are being studied. This note provides an update on anti-Xa DOAC interference and different strategies available in current practice. It also underlines the importance of communication between biologists and clinicians on anticoagulant treatments received by patients.

The Pharmacogenetic Variability Associated with the Pharmacokinetics and Pharmacodynamics of Rivaroxaban in Healthy Chinese Subjects: A National Multicenter Exploratory Study

PurposeThis study aimed to explore the pharmacogenetic variability associated with the pharmacokinetics (PK) and pharmacodynamics (PD) of rivaroxaban in healthy Chinese subjects. MethodsThis was a multicenter study that included 304 healthy adults aged 18 to 45 years with unknown genotypes. All participants were administered a single dose of rivaroxaban at 10 mg, 15 mg, or 20 mg. PK and PD parameters were measured, and exome-wide association analysis was conducted. FindingsSixteen SNPs located on 11 genes influenced the AUC0-t. Among these, the 3 most influential genes were MiR516A2, PARP14, and MIR618. Thirty-six SNPs from 28 genes were associated with the PD of rivaroxaban. The 3 most influential genes were PKNOX2, BRD3, and APOL4 for anti-Xa activity, and GRIP2, PLCE1, and MLX for diluted prothrombin time (dPT). Among them, BRD3 played an important role in both the PK and PD of rivaroxaban. Anti-Xa activity (ng/mL) differed significantly among subjects with BRD3 rs467387: 145.1 ± 55.5 versus 139.9 ± 65.1 versus 164.0 ± 68.6 for GG, GA, and AA carriers, respectively (P = 0.0002). ImplicationsThis study found that that the regulation of the BRD3 gene might affect the PK and PD of rivaroxaban, suggesting that it should be studied as a new pharmacologic target. The correlation between this gene locus and clinical outcomes has yet to be verified in patients undergoing clinical treatment.

Quantifying Residual Rivaroxaban Plasma Concentration after Antagonization with Andexanet Alfa: A Difficult Task in Routine Clinical Practice.

We describe the case of a 38-year-old man with a history of chronic portal vein thrombosis who presented with abdominal pain after a transjugular intrahepatic portosystemic shunt procedure. Under anticoagulation therapy with rivaroxaban, he experienced active splenic bleeding, leading to hemodynamic instability. Emergency interventions, including andexanet alfa and nanoparticle administration, successfully stopped the bleeding. However, routine tests showed persistently high rivaroxaban levels despite reversal with andexanet alfa. This case report shows that next to standard anti-Xa activity assay, high-performance liquid chromatography is as well unreliable in this regard. In contrast, viscoelastic tests might better serve as indicators of the efficacy of the reversal. The availability of modified anti-Xa tests is urgently needed, to monitor the effects of andexanet alfa reversal.

Andexanet alfa versus non-specific treatments for intracerebral hemorrhage in patients taking factor Xa inhibitors - Individual patient data analysis of ANNEXA-4 and TICH-NOAC.

Data comparing the specific reversal agent andexanet alfa with non-specific treatments in patients with non-traumatic intracerebral hemorrhage (ICH) associated with factor-Xa inhibitor (FXaI) use are scarce. The study aimed to determine the association between the use of andexanet alfa compared with non-specific treatments with the rate of hematoma expansion and thromboembolic complications in patients with FXaI-associated ICH. We performed an individual patient data analysis combining two independent, prospective studies: ANNEXA-4 (180 patients receiving andexanet alfa, NCT02329327) and TICH-NOAC (63 patients receiving tranexamic acid or placebo ± prothrombin complex concentrate, NCT02866838). The primary efficacy outcome was hematoma expansion on follow-up imaging. The primary safety outcome was any thromboembolic complication (ischemic stroke, myocardial infarction, pulmonary embolism, or deep vein thrombosis) at 30 days. We used binary logistic regression models adjusted for baseline hematoma volume, age, calibrated anti-Xa activity, times from last intake of FXaI, and symptom onset to treatment, respectively. Among 243 participants included, the median age was 80 (IQR 75-84) years, baseline hematoma volume was 9.1 (IQR 3.4-21) mL and anti-Xa activity 118 (IQR 78-222) ng/mL. Times from last FXaI intake and symptom onset to treatment were 11 (IQR 7-16) and 4.7 (IQR 3.0-7.6) h, respectively. Overall, 50 patients (22%) experienced hematoma expansion (ANNEXA-4: n=24 (14%); TICH-NOAC: n=26 (41%)). After adjusting for pre-specified confounders (baseline hematoma volume, age, calibrated anti-Xa activity, times from last intake of FXaI, and symptom onset to treatment, respectively), treatment with andexanet alfa was independently associated with decreased odds for hematoma expansion (aOR 0.33, 95% CI 0.13-0.80, p = 0.015). Overall, 26 patients (11%) had any thromboembolic complication within 30 days (ANNEXA-4: n=20 (11%); TICH-NOAC: n=6 (10%)). There was no association between any thromboembolic complication and treatment with andexanet alfa (aOR 0.70, 95% CI 0.16-3.12, p = 0.641). The use of andexanet alfa compared to any other non-specific treatment strategy was associated with decreased odds for hematoma expansion, without increased odds for thromboembolic complications.

Prolonged coagulation times in severe fever with thrombocytopenia syndrome virus infection, the indicators of heparin-like effect and increased haemorrhagic risk.

Prolonged coagulation times, such as activated partial thromboplastin time (APTT) and thrombin time (TT), are common in patients infected with severe fever with thrombocytopenia syndrome virus (SFTSV) and have been confirmed to be related to patient's poor outcome by previous studies. To find out the reason for prolonged coagulation time in patients with SFTSV infection, and whether it predicts haemorrhagic risk or not. Seventy-eight consecutive patients with confirmed SFTSV infection were enrolled in this prospective, single-centre, observational study. Several global and specific coagulation parameters of these patients on admission were detected, and the haemorrhagic events during hospitalization and their outcomes were recorded. Most of the enrolled patients had prolonged APTT (82.1%) and TT (80.8%), normal prothrombin time (83.3%) and intrinsic coagulation factors above haemostatic levels (97.4%). The heparin-like effect was confirmed by a protamine neutralization test and anti-Xa activity detection in most patients. Interestingly, the APTT and TT results were significantly positively correlated with the levels of endothelial markers and viral load, respectively. The APTT was independently associated with the haemorrhage of patients. The prolonged APTT and TT of SFTS patients may mainly be attributed to endogenous heparinoids and are associated with increased haemorrhagic risk.

Evaluation of anticoagulant effect and predicted dose of low molecular weight heparin in hemodialysis by anti-Ⅹa factor activity

The purpose of this study was to explore the reasonable dose of low molecular weight heparin (LMWH) in hemodialysis (HD) and the strategy of preventing extracorporeal circuit coagulation (ECC). A retrospective case-control study included patients who used LMWH for anticoagulation during maintenance hemodialysis (MHD) in the Hemodialysis Center of Beijing Hospital from December 2020 to January 2021. Basic data such as weight, height, basic kidney disease, dialysis age and anti-Ⅹa factor activity before, during and after dialysis were collected. A total of 46 patients were enrolled in this study, including 5 patients in coagulation group (10.9%) and 41 patients in non-coagulation group (89.1%). The anti-Ⅹa factor activity reached its peak at 0.5 h after the start of HD. The level of anti-Ⅹa factor was incorporated into the receiver operating characteristic curve (ROC curve). The results showed that the area under the ROC curve (AUC) was 0.802 (95% confidence interval: 0.651-0.54, P=0.029), and the cutoff was 0.31 IU/ml (sensitivity 1, specificity 0.683). It is suggested that the body surface area should be used as the basis to estimate the anticoagulant dose of LMWH in HD, and the activity of HD 4 h anti-Ⅹa factor ≤0.31 IU/ml, which is of diagnostic value for ECC. In addition, the results of binary logistic regression analysis showed that dialysis age was an independent risk factor for ECC (OR value 1.319, 95%CI 1.052-1.654, P=0.017). In summary, this study reveals that dialysis age may be a risk factor for ECC and that the activity of HD 4 h anti-Ⅹa factor ≤0.31 IU/ml can be used as a potential diagnostic cut-off point for ECC in HD patients, which provides a scientific basis for monitoring strategies to prevent blood coagulation in HD filters.

The use of andexanet alpha in the Polish setting: An interdisciplinary protocol. Expert consensus statement of the Polish Cardiac Society.

Andexanet alfa (AA) is a recombinant inactive analog of human activated factor X (FXa), effectively reversing the effects of its inhibitors - rivaroxaban and apixaban, which are available in Poland. The drug was approved for clinical use registration after the publication of the results of the ANNEXA-4 trial (Andexanet Alfa, a Novel Antidote to the Anticoagulation Effects of FXa Inhibitors 4), in which its efficacy in restoring hemostasis in life-threatening hemorrhages in patients receiving using the aforementioned anticoagulants was demonstrated. Hence, AA is now recommended for patients on apixaban or rivaroxaban therapy with massive and uncontrollable hemorrhages, including hemorrhagic strokes (HS) and gastrointestinal bleeding. Drug-specific chromogenic anti-Xa assays are generally best suited for estimating rivaroxaban and apixaban plasma levels, aside from direct assessment of their concentrations. The absence of anti-Xa activity, determined using these assays, allows us to rule out the presence of clinically relevant plasma concentrations of any FXa inhibitor. On the other hand, the dose of AA should not be modified based on the results of coagulation tests, as it depends solely on the time that elapsed since the last dose of FXa inhibitor and oon the dose and type of FXa inhibitor. AA is administered as an intravenous (i.v.) bolus, followed by an i.v. infusion of the drug. The maximum reversal of anti-Xa activity occurs within two minutes of the end of the bolus treatment, with the continuation of the continuous i.v. infusion allowing the effect to be maintained for up to two hours afterwards. Because anticoagulant activity can reappear after the infusion is completed, it is currently unclear at what point after AA administration FXa inhibitors or heparin should be re-administered. In Poland AA is starting to become available and its urgent need to administer it to patients with severe bleeding on apixaban or rivaroxaban.

New anticoagulant protein from medicinal leech

The saliva of the medicinal leech contains various anticoagulants. Some of them, such as hirudin, are well known. However, it is reasonable to believe that not all anticoagulant proteins from medicinal leech saliva have been identified. We previously performed a comprehensive study of the transcriptome, genome, and proteome of leech salivary gland cells, which led to the discovery of several previously unknown hypothetical proteins that may have anticoagulant properties. Subsequently, we obtained a series of recombinant proteins and investigated their impact on coagulation in in vitro assays. We identified a previously undescribed protein that exhibited a high ability to suppress coagulation. The His-tagged recombinant protein was expressed in Escherichia coli and purified using metal chelate chromatography. To determine its activity, commonly used coagulation methods were used: activated partial thromboplastin time, prothrombin time, and thrombin inhibition clotting assay. Clotting and chromogenic assays for factor Xa inhibition were performed to evaluate anti-Xa activity. We used recombinant hirudin as a control anticoagulant protein in all experiments. The new protein showed significantly greater inhibition of coagulation than hirudin at the same molar concentrations in the activated partial thrombin time assay. However, hirudin demonstrated better results in the direct thrombin inhibition test, although the tested protein also exhibited the ability to inhibit thrombin. The chromogenic analysis of factor Xa inhibition revealed no activity, whereas the clotting test for factor Xa showed the opposite result. Thus, a new powerful anticoagulant protein has been discovered in the medicinal leech. This protein is homologous to antistatin, with 28 % identical amino acid residues. The recombinant protein was expressed in E. coli. This protein is capable of directly inhibiting thrombin, and based on indirect evidence, other proteases of the blood coagulation cascade have been identified.