Search Results (79)

Background/Objectives: Protein Z (PZ) and the protein Z-dependent protease inhibitor (ZPI) are vitamin K-dependent regulators of coagulation that inhibit activated factor Xa. Their relevance in ischemic stroke (IS) remains insufficiently characterized, with inconsistent evidence regarding their association with stroke severity and outcomes. This study aimed to evaluate the concentrations and dynamics of PZ and ZPI in the acute phase of IS in patients treated with intravenous thrombolysis or conservative therapy and to assess their potential prognostic significance. Methods: Eighty-four patients with acute IS were enrolled and divided into two groups: group I treated with intravenous thrombolysis (rt-PA) and group II managed conservatively. PZ and ZPI concentrations were measured using ELISA on admission (day 1) and on day 7. Associations with factor X activity, the modified Rankin Scale (mRS), and the National Institutes of Health Stroke Scale (NIHSS) were analyzed using nonparametric tests and Spearman correlations (p < 0.05). Results: PZ concentrations were significantly higher in thrombolysis-treated patients than in conservatively managed patients both on day 1 (median: 2810.05 vs. 2178.50 ng/mL; p = 0.024) and day 7 (2982.90 vs. 2286.50 ng/mL; p = 0.026). A slight negative correlation between PZ and mRS on day 7 was observed in the conservative group (r = −0.360; p = 0.043). In thrombolysis-treated patients with dyslipidemia, PZ increased from day 1 to day 7, whereas it decreased in those without dyslipidemia. No significant correlations were found between PZ, ZPI, or factor X and NIHSS or ASTRAL scores. Conclusions: Higher PZ concentrations in the acute phase of IS—particularly in rt-PA-treated patients—may reflect differences related to the timing of the acute ischemic process and reperfusion status, suggesting potential utility as markers of stroke severity or outcome. Full article

The introduction of direct oral anticoagulants (DOACs), particularly factor Xa (FXa) inhibitors, has transformed the prevention and treatment of thromboembolic events. These agents have largely replaced vitamin K antagonists across most indications due to their predictable pharmacokinetics, reduced rates of intracranial bleeding, and overall ease of use. Nevertheless, a substantial residual bleeding risk remains, particularly gastrointestinal bleeding and clinically relevant non-major bleeding in elderly, frail, or polymedicated patients. Furthermore, the management of patients with severe renal dysfunction, active cancer, especially gastrointestinal or genitourinary malignancies and those requiring complex pharmacological regimens, continues to pose significant challenges. These limitations have intensified interest in targeting earlier steps of the coagulation cascade, specifically factor XI (FXI) and its activated form (FXIa). FXI occupies a unique mechanistic position: it contributes substantially to pathological thrombosis while playing only a limited role in physiological hemostasis. Genetic, observational, and mechanistic evidence consistently demonstrates that FXI deficiency confers protection against venous thromboembolism and cardiovascular events while causing minimal spontaneous bleeding. This biological paradigm has catalyzed the development of novel FXI/FXIa inhibitors, including small-molecule agents (asundexian, milvexian) and biological therapies (abelacimab). Clinical trials such as AXIOMATIC-TKR, PACIFIC-AF, and OCEANIC-AF, and ongoing programmes including ASTER and MAGNOLIA suggest that FXI inhibition may preserve antithrombotic efficacy while substantially reducing bleeding risk. This review summarizes the current landscape of oral FXa inhibitors, outlines the biological rationale for FXI/FXIa inhibition, and discusses the evolving clinical evidence supporting what may represent the next major advance in anticoagulant therapy. Full article

Background/Objectives: Different anti-Xa assays are routinely used to evaluate the plasma concentrations of direct factor X inhibitors (DXIs) rivaroxaban and apixaban, despite a lack of data on assay equivalence. Information on assay performance is particularly important at clinical decision cut-offs, such as 50 ng/mL or 30 ng/mL. The aim of this study was to evaluate the equivalence of different anti-Xa assays with the reference LC-MS/MS method for measuring rivaroxaban and apixaban concentrations in a multicenter study. In addition, the usefulness of the dRVVT as a simple coagulation test for emergency situations was evaluated. Methods: We included 122 patients with atrial fibrillation. Trough and peak blood samples were collected from 60 patients treated with rivaroxaban and 62 patients treated with apixaban. Rivaroxaban and apixaban plasma levels were measured by LC–MS/MS. Different anti-Xa assays were used in three laboratories to evaluate equivalence. Results: The concentrations in the analyzed samples ranged from 2 to 781 ng/mL for rivaroxaban and 9 to 568 ng/mL for apixaban. Only one of the anti-Xa assays gave equivalent results to LC-MS/MS for rivaroxaban, and none for apixaban. All anti-Xa assays significantly underestimated apixaban concentration, with a proportional bias between 10% and 20%. A high correlation was found between DXI concentration and dRVVT clotting time, but dRVVT was not consistently prolonged at clinically relevant DXI concentrations in plasma. Conclusions: Only one of the anti-Xa assays showed equivalence with LC-MS/MS for rivaroxaban, and none for apixaban. Several anti-Xa assays provided reliable results for rivaroxaban in the range of clinically relevant cut-off values, but none for apixaban, which could expose patients to a higher risk of bleeding and urgently needs further clinical research. The dRVVT test was not sensitive enough for reliable detection of clinically relevant DXI plasma concentrations and therefore cannot replace the anti-Xa assay in emergency situations. Full article

The utilisation of cardiopulmonary bypass (CPB) during cardiac surgery is often associated with complex haemostatic perturbations, frequently manifesting as a paradoxical risk of both bleeding and thrombosis. This is postulated to be driven by systemic inflammation, endothelial activation and contact activation of the coagulation cascade due to extracorporeal circulation. However, the coronavirus disease 2019 (COVID-19) pandemic revealed a unique hypercoagulable state, termed COVID-19-associated coagulopathy (CAC), also observed in those vaccinated against COVID-19. CAC displays similar physiological manifestations to those of disseminated intravascular coagulation (DIC), characterised by elevated fibrinogen and D-dimer values. The precise pathogenesis of CAC requires further elucidation though proposed mechanisms include: an exaggerated inflammatory response to COVID-19 infection or antibody proliferation due to vaccination, direct epithelial cell damage mediated by angiotensin converting enzyme 2, and ‘hypoxithrombosis’. CAC has since provided a unique framework to understand and potentially mitigate coagulation complications encountered during CPB in the post-pandemic era, as it is no longer sufficient to view COVID-19 as a transient influence on surgical risk. Rather, it must be recognized as a persistent modifier of the haemostatic environment across the population, with direct implications upon patient selection, intraoperative management and postoperative care in cardiac surgery. This review examines the pathological drivers behind CAC alongside the insights obtained from CAC management during ECMO deployment, to investigate the potential translation of such knowledge into improved anticoagulation strategies and monitoring during cardiac surgery. The use of alternative anticoagulants including factor XI inhibitors and the modulation of heparinase activity offers promising avenues to attenuate coagulopathies more commonly observed during CPB in the post-pandemic climate, whilst anti-Xa assays and viscoelastic testing have offered applicability to modern perfusion practices. By bridging the knowledge gained during the pandemic with that of conventional CPB, this review aims to inform future strategies for haemostasis management in cardiac surgery in a novel cohort of surgical patients. Full article

To develop efficient and structurally novel anticoagulants, a library of new hybrid molecules—(Z)-1-(2-(4-arylthiazol-2-yl)hydrazineylidene)-5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-2-ones—was designed and synthesized through a two-step approach. The reaction of pyrrolo[3,2,1-ij]quinoline-1,2-diones with thiosemicarbazide produced thiosemicarbazones, which were subsequently reacted with α-bromoacetophenones. The structure of the resulting compounds was determined by HPLC-HRMS-ESI analysis, ¹H NMR spectroscopy, and ¹³C NMR spectroscopy. X-ray diffraction analysis unambiguously confirmed the structure of the resulting substances. The synthesized compounds were tested for their anticoagulant activity in vitro. Among the tested derivatives, two substances have a dual effect and exhibit 98–100% inhibitory ability against blood coagulation factors Xa and XIa at 30 μM. IC₅₀ values were also evaluated for these compounds. The results obtained show the high potential of the synthesized derivatives in the development of new multitarget anticoagulant drugs. The docking studies confirmed the experimental results. Full article

Background: Direct oral anticoagulants (DOACs) are generally preferred over warfarin for preventing arterial and venous thromboembolism. However, the efficacy and safety of DOACs in patients with extremely low body weight (BW) are uncertain. This study investigates anti-factor Xa (anti-FXa) activity of apixaban and compares it between patients with normal BW (>50 kg) and underweight (≤50 kg). Methods: We enrolled 150 patients on branded generic apixaban (Apixan^TM) for atrial fibrillation (AF), venous thromboembolism, and intracardiac thrombus. Anti-FXa activity of apixaban was measured at peak concentration (C_peak) and trough concentration (C_trough) after at least one week of therapy. Results: Mean age was 64.0 ± 12.7 years, with 53.3% being male. Mean BW was 61.3 ± 15.3 kg. Of the 150 patients, 132 (88%) had AF, and 43 (28.7%) had low BW. Overall, 87.3% and 84.7% of patients had C_trough and C_peak within the expected range. Underweight patients had significantly higher mean C_trough and C_peak than normal BW patients. A higher proportion of low-BW patients exceeded the expected C_peak range compared to normal-BW patients (25.6% vs. 3.7%, p < 0.001). Low BW was the only independent predictor of exceeding C_peak specified range (adjusted OR 4.87, 95% CI 1.31–18.15, p = 0.018). Conclusions: Most patients maintained apixaban levels within expected ranges, but those with low BW were more likely to exceed the specified range of C_peak. Full article

Thrombotic diseases represent a significant global health burden, particularly for middle-aged and elderly populations. Medicinal leeches, such as Hirudinaria manillensis and Whitmania pigra, have been traditionally used for their anticoagulant properties. The genomes of these leeches each harbor three lefaxin genes, which are designated lefaxin_Hman1–3 and lefaxin_Wpig1–3, respectively. We conducted genomic and transcriptomic sequencing on wild populations of both species. Bioinformatics tools were employed to analyze intraspecific variation, molecular evolution, and protein structures. We expressed recombinant lefaxin proteins in Pichia pastoris and assessed their anticoagulant activities using in vitro coagulation assays. H. manillensis exhibited greater genetic diversity and stability, whereas W. pigra showed higher expression levels and hydrophilicity. Both species exhibited purifying selection, indicating conserved function, and their lefaxin structures are similar to the archetypal lefaxin (UniProt No. P86681.1). W. pigra lefaxins bound Factor Xa more effectively. W. pigra lefaxins exhibited more robust anticoagulant activity in vitro compared to those from H. manillensis. W. pigra, a non-hematophagous leech, shows potent anticoagulant activity through lefaxins, challenging traditional views on leech efficacy. This study underscores the potential of lefaxins as therapeutic targets for thrombotic diseases and highlights the need to reconsider the use of various leech species in medicine. Full article

Metabolic dysfunction-associated steatotic liver disease (MASLD) has recently become the leading cause of chronic liver disease and can progress to hepatocellular carcinoma (HCC) through multiple pathogenic mechanisms. Protease-activated receptor 2 (PAR2) is a G-protein-coupled receptor activated by proteases such as trypsin, tryptase or coagulation factors VII and Xa. Recent studies have shown that PAR2 expression is increased in the liver of patients with MASLD or liver fibrosis. Its activation is linked to metabolic dysfunction through several pathways, including SREBP1c activation, AMPK inhibition and Akt-induced insulin resistance. Inhibition of PAR2 has been effective in reducing MASLD progression in different animal models. Notably, PAR2 blockade has also been effective in more advanced stages of the disease by dampening chronic inflammation and fibrogenesis through the inhibition of hepatic stellate cell activation and of TGF-β and SerpinB3 production. PAR2 also plays a role in cancer development, promoting tumour proliferation, angiogenesis and expression of immune checkpoint inhibitors (like PD-L1, CD47 and CD24). Due to its multifaceted involvement in liver disease, PAR2 is emerging as a key therapeutic target in this clinical context. This review aims to summarise current knowledge on PAR2′s role in MASLD and its potential as a therapeutic target. Full article

Background: Administering intravenous thrombolysis (IVT) in patients with acute ischemic stroke (AIS) on direct oral anticoagulants (DOACs) remains a clinical challenge. Current guidelines restrict IVT within 48 h of DOAC intake unless anticoagulant activity can be confidently excluded. However, reliable medication histories are often unavailable, and conventional coagulation tests inadequately detect DOAC activity. This study evaluated whether viscoelastic point-of-care testing (ClotPro^®) could identify the absence of anticoagulant effect in AIS patients on DOACs, thus enabling IVT administration and potentially improving clinical outcomes. Methods: We conducted a prospective observational cohort study of 40 AIS patients with documented DOAC use, admitted between February 2023 and May 2025. ClotPro^® was performed at admission using the Russell’s viper venom (RVV) assay for factor Xa inhibitors and the ecarin clotting time (ECT) assay for dabigatran. Subtherapeutic anticoagulation was defined as a clotting time (CT) of <100 s for RVV and <180 s for ECT, respectively. Patients identified as being subtherapeutic were assessed for IVT eligibility. To evaluate IVT effects, we performed propensity score-matched bootstrap resampling (1000 iterations), matching patients by age, admission National Institutes of Health Stroke Scale (NIHSS), and pre-stroke modified Rankin Scale (mRS). Primary endpoints were NIHSS-shift (change from admission to 72 h) and mRS-shift (change from pre-stroke mRS to 90-day mRS). Predictors of outcomes were analyzed using multivariate regression models. Results: ClotPro^® identified 15/40 patients (37.5%) as subtherapeutic, all on factor Xa inhibitors. Of these, seven received IVT. In matched analyses, IVT-treated patients showed a numerically greater neurological improvement than untreated patients (mean NIHSS-shift: −2.83 vs. 3.94; mean difference: −6.76, 95% confidence interval [CI]: −24.00 to 7.55; p = 0.495). Functional outcome by mRS-shift showed only minor differences between groups (2.74 vs. 2.10 mean difference: 0.64; 95% CI: −2.00 to 2.50; p = 0.510). IVT showed a favorable trend for early neurological recovery (p = 0.081) but was not independently associated with functional outcome (p = 0.380). Conclusions: ClotPro^® identified a substantial subset of AIS patients on DOAC therapy without measurable anticoagulant activity, enabling IVT in cases that would otherwise have been excluded based on medication history. These findings support the feasibility of ClotPro^®-guided decision-making in acute stroke care and highlight its potential to improve IVT selection by enabling real-time assessment of coagulation status at the bedside. Full article

Background/Objectives: Endovascular aneurysm repair (EVAR) of the aorta may trigger an inflammatory response that affects coagulation. In the EVAR of para-renal and thoraco-abdominal aortic aneurysms, the implants are more complex and the duration of surgery is longer. However, the exact pathophysiological mechanisms of coagulation activation are not yet well understood. The primary aim of this study is to investigate the effects of complex EVAR of para-renal and thoraco-abdominal aortic aneurysms on the coagulation status of patients. Methods: This prospective observational study (STROBE), approved and registered by the Ethics Committee of the University Hospital of Larissa (UHL) (NCT06432387), will enroll consecutive patients undergoing elective EVAR of para-renal and thoraco-abdominal aortic aneurysms. Exclusion criteria: Refusal to participate, previous surgery within 3 months, American Society of Anesthesiologists physical status (ASA PS) > 3, known history of thrombophilia or functional platelet dysfunction. Perioperative laboratory tests will be performed according to institutional guidelines. These include a complete blood count, conventional coagulation tests, and kidney and liver function tests. In addition, the following parameters will be determined: von Willebrand factor, factors VIII and XI, D-dimers, fibrinogen, Adamts-13, anti-Xa, platelet activation (multiplate), and high-sensitivity troponin. Blood samples will be taken pre-operatively before induction of anesthesia (01), on postoperative day 1 (02), and on postoperative day 3–4 (03). During hospitalization, myocardial injury after non-cardiac surgery (MINS), major adverse cardiovascular events after non-cardiac surgery (MACE), acute kidney injury (AKI), post-implantation syndrome (PIS), and death from any cause will be recorded. In addition, our patients will be reviewed at 30 days, 3, 6, and 12 months for MACE, implant failure, or death from any cause. All enrolled patients will be treated by the same medical team at UHL according to the indications. According to our power analysis, for a cohort of patients with three consecutive measurements, 58 patients should be included in the study. To compensate for possible dropouts, the sample size was increased to 65 patients. Conclusions: The results of the present study could help physicians to better understand the effects of complex EVAR of para-renal and thoraco-abdominal aortic aneurysms on blood coagulation and platelet activation. Full article

Coagulation testing is commonly used in the intensive care unit (ICU) to monitor and manage the hemostatic balance, assess bleeding risk, and guide anticoagulant therapy. Routine tests used for this purpose include prothrombin time, activated partial thromboplastin time, fibrinogen, and anti-Xa assays. Some of the drugs commonly used in critically ill patients may influence coagulation assays by interacting in vitro with reagents or in vivo with coagulation pathways, thus altering the coagulation cascade and the fibrinolytic pathway. While the pharmacological effects of drugs on coagulation are usually documented, to our knowledge, no comprehensive review article has been published to date. In this review, we have conducted a critical analysis of the literature to define: (1) the impact of hydroxocobalamin, intravenous lipid emulsion, and propofol on chromogenic assays; (2) the impact of PEGylated compounds, emicizumab, recombinant activated factor VII, antibiotics, and sugammadex on chronometric assays; (3) the challenges associated with bridging anticoagulation in the ICU as well as the effect of N-acetylcystein, serotonin reuptake inhibitors, and tramadol on the hemostasis system. For each drug, we specify the routine coagulation assay that is impacted, whether this is linked to an in vitro interference or an in vivo effect, and the potential consequences on patient management. Full article

The Philippines has a high diversity of venomous snake species, but there is minimal information on their envenomation effects. This is evidenced by the small number of case reports, the poor reporting of envenomation cases, and the absence of specific antivenoms apart from one against the Philippine cobra (Naja philippinensis). This study sought to profile the action of selected Philippine pit viper venoms on blood coagulation and to investigate whether commercially available non-specific antivenoms can provide adequate protection against these venoms. Venom from the pit vipers Trimeresurus flavomaculatus and Trimeresurus mcgregori were subjected to coagulation assays, antivenom cross-neutralization tests, and thromboelastography. Venoms from both species were able to clot human plasma and isolated human fibrinogen. Consistent with pseudo-procoagulant/thrombin-like activity, the resulting fibrin clots were weak and transient, thereby contributing to net anticoagulation through the depletion of fibrinogen levels. Clotting factors fIXa and fXa were also inhibited by the venoms, further contributing to the net anticoagulant activity. Monovalent and polyvalent antivenoms from the Thai Red Cross Society were effective against both venoms, indicating cross-neutralization of venom toxins; the polyvalent antivenom was able to rescue fibrinogen clotting to a greater degree than the monovalent antivenom. Our findings highlight the coagulopathic effects of these pit viper venoms and suggest the utility of procuring the non-specific antivenoms for areas in the Philippines with a high risk for pit viper envenomation. Full article

Protease-activated receptor 2 (PAR2) is a seven-transmembrane, G-protein-coupled receptor that is activated by coagulation proteases such as factor VIIa and factor Xa and other serine proteases. It is a potential therapeutic target for kidney injury, as it enhances inflammatory and fibrotic responses via the nuclear factor-kappa B and mitogen-activated protein kinase cascades. The body of knowledge regarding the role of PAR2 in kidney disease is currently growing, and its role in various kidney disease models, such as acute kidney injury, renal fibrosis, diabetic kidney disease, aging, and thrombotic microangiopathy, has been reported. Here, we review the literature to better understand the various aspects of PAR2 in kidney disease. Full article

Background: Andexanet alfa is a specific antidote for factor Xa (FXa) inhibitors. It is licensed to treat patients under FXa inhibitor therapy with life-threatening bleeding. Concomitantly, volume expanders are used to compensate for blood loss and maintain circulation. The competitive binding of andexanet to FXa inhibitors may be disrupted due to hemodilution, as shown by laboratory assays with high sample dilution. This study investigated the efficacy of andexanet for the reversal of FXa inhibitors under hemodilution. Methods: Blood from 10 healthy volunteers was anticoagulated with rivaroxaban and subsequently treated with four different volume expanders (Ringer’s solution, 4% gelatine, 5% and 20% human albumin (HA)) at two dilution levels (20% and 50%). After anticoagulation and hemodilution, andexanet was added according to the high-dose protocol. Blood samples were analyzed using a Russell’s viper venom (RVV) test on a Clot Pro^® device, a thrombin generation assay, a fully automated coagulation analyzer and a chromogenic anti-FXa activity assay. Results: After anticoagulation, the median rivaroxaban concentration was 272 ng/mL (IQR 254–353). Anticoagulation with rivaroxaban caused a significant impairment of all coagulation parameters, which was further aggravated by hemodilution. After the administration of andexanet, coagulation parameters in anticoagulated samples were reversed to near baseline in all groups. Andexanet administration decreased the rivaroxaban plasma concentration in all groups to a median of <10 ng/mL. In the anticoagulated, non-hemodiluted samples, anti-FXa activity was reduced by 98%. The anti-FXa activity in the anticoagulated, hemodiluted samples was reduced by approximately 96% in the 20% diluted samples and by about 93% in the 50% diluted samples. Conclusions: Our data indicate that FXa inhibitor reversal with andexanet is about 5% less effective with 50% hemodilution than in non-hemodiluted samples. Full article

Background: The therapeutic effects of oral anticoagulant drugs for nonvalvular atrial fibrillation (NVAF) suggest that the three factor Xa (FXa) inhibitors may have distinct safety profiles, though this is not yet fully conclusive. This study investigated the current dosing of rivaroxaban, apixaban, and edoxaban by monitoring drug plasma concentration (PC) and coagulation activity from the viewpoint of the safety. Methods and results: This multicenter clinical study monitored the drug PC and two coagulation biomarkers (fibrinogen and fibrin monomer complex [FMC]) at peak and trough timing in 268 outpatients taking rivaroxaban (n = 72), apixaban (n = 71), and edoxaban (n = 125) for NVAF. Doses were adjusted based on the dose-adjustment criteria of each drug. Referencing our previous study, peak drug PC remained below the cut-off level for predicting bleeding events except in eight patients (rivaroxaban, n = 3; apixaban, n = 2; edoxaban, n = 3) in whom bleeding events occurred. Among them, two (one each on rivaroxaban and edoxaban) had a peak drug PC below the cut-off level. Drug PCs widely varied from peak to trough, whereas FMC levels, reflecting thrombin activity, remained within the normal range (<6.1 µg/mL) regardless of PC variations. These results indicated that the anticoagulant effects of these drugs persisted throughout the day regardless of the drug PC levels, dosage, and dosing frequency. Regarding the change over time in peak PC, the elevation over time developed more in rivaroxaban (29/57; 50.9%, p < 0.05) than in edoxaban (32/101; 31.7%), and rivaroxaban tended to accumulate more than edoxaban. Conclusions: Although drug PC levels of once-daily FXa inhibitors widely varied from peak to trough, FMC levels were maintained within the normal range without daily variations. Rivaroxaban also tended to accumulate over time. The results indicate the low risk of thrombotic events with once-daily FXa inhibitors and its correspondence to the twice-daily regimen. Full article