Bleeding Risk Assessment in Patients with Venous Thromboembolism

A novel role for protein disulfide isomerase ERp18 in venous thrombosis

BACKGROUND

Previous studies using genetically modified mouse models and inhibitors have shown that protein disulfide isomerase (PDI) family plays a significant role in arterial thrombosis. However, their role in venous thrombosis remains unknown. In this study, using gene-modified mouse models, we determined whether PDI family members contribute to venous thrombosis.

METHODS

Mice deficient of the PDI family members, including PDI, PDIp, ERp57, PDIr, ERp5, ERp27, ERp29, TMX4, ERdj5, and ERp18, were generated. The venous thrombosis phenotype of these deficient strains was evaluated using an inferior vena cava (IVC) stenosis model. Moreover, the recombinant human ERp18 (rhERp18) protein was generated and its reductase activity was assessed using a Di-E-GSSG method. The effect of ERp18 in venous thrombosis was tested in the IVC stenosis model. The levels of von Willebrand factor (vWF) at the site of venous thrombi were measured.

RESULTS

The mice deficient in PDI, PDIp, ERp57, PDIr, ERp5, ERp27, ERp29, TMX4, and ERdj5 had no effects on venous thrombosis in the IVC stenosis model. However, the mice lacking ERp18 developed significantly less venous thrombosis compared with the WT mice. ERp18 contains one CGAC active motif. When WT or ERp18-KO mice received injection of rhERp18-WT or inactive rhERp18-mutant (Mut) protein whose CGAC was mutated to SGAS, rhERp18-Mut protein inhibited venous thrombosis in the IVC stenosis model, suggesting that the role of ERp18 is dependent on its enzymatic activity. As determined by enzyme-linked immunosorbent assay (ELISA) and immunofluorescence staining, the levels of vWF in the plasma at the site of venous thrombus in ERp18-KO mice were significantly lower than those in WT mice.

CONCLUSION

ERp18 enhances the development of venous thrombosis, and its function and its enzymatic activity and regulation of the vWF release are involved.

Monitoring anti-Xa levels in elderly medical patients undergoing thromboprophylaxis: A prospective cohort study

INTRODUCTION

Given the rising incidence of venous thromboembolism (VTE) and insufficient thromboprophylaxis dosing evidence in certain patients, the precise monitoring of anti-Xa (aFXa) levels is crucial. The aim of this study is to investigate the achievement of prophylactic aFXa levels in medical inpatients who were receiving parenteral anticoagulant and to evaluate the impact of various factors on aFXa levels.

METHODS

This is a single-center observational cohort study conducted on patients admitted to the Department of Internal Medicine at the University Hospital of Heraklion, Greece, from March to August 2023. These individuals received low-molecular-weight heparins thromboprophylaxis owing to an increased risk of VTE. Data regarding demographics, past medical history, and somatometric and laboratory findings were recorded. The established range for peak prophylactic aFXa levels was defined as 0.2-0.5 IU/mL.

RESULTS

In this study, we enrolled 150 individuals [91 (60.7%) women] with a mean age of 80.0 ± 14.1 years. Sixty-two (41.4%) patients exhibited non-prophylactic peak aFXa levels. Supratherapeutic levels were observed in all underweight patients and subtherapeutic levels in 12 of 13 obese patients in class II and III. A multivariate linear regression analysis revealed that body weight, cancer, and the Charlson Comorbidity Index (CCI) were independent factors influencing aFXa levels.

CONCLUSIONS

Our study reveals a substantial portion of medical elderly inpatients on thromboprophylaxis with non-prophylactic aFXa levels, with a notable prevalence among underweight and severely obese patients. Body weight, cancer, and CCI were identified as independent factors influencing aFXa levels, advocating for tailored thromboprophylaxis strategies. Further research is warranted to validate personalized dosing approaches and to enhance clinical decision-making. Geriatr Gerontol Int 2024; 24: 587-594.

Validation of the RIETE, Kuijer, and HAS-BLED Models to Assess 3-Month Bleeding Risk in Anticoagulated Patients Diagnosed with Venous Thromboembolic Disease

OBJECTIVE

To evaluate the discriminative ability and calibration of the RIETE, Kuijer, and HAS-BLED models for predicting 3-month bleeding risk in patients anticoagulated for venous thromboembolism (VTE).

METHODS

External validation study of a prediction model based on a retrospective cohort of patients with VTE seen at the Hospital Universitario San Ignacio, Bogotá (Colombia) between July 2021 and June 2023. The calibration of the scales was evaluated using the Hosmer-Lemeshow test and the ratio of observed to expected events (ROE) within each risk category. Discriminatory ability was assessed using the area under the curve (AUC) of a ROC curve.

RESULTS

We analyzed 470 patients (median age 65 years, female sex 59.3%) with a diagnosis of deep vein thrombosis in most cases (57.4%), 5.7% bleeding events were observed. Regarding calibration, adequate calibration cannot be ruled out given the limited number of events. The discriminatory ability was limited with an area under the curve (AUC) of 0.48 (CI 0.37-0.59) for Kuijer Score, 0.58 (CI 0.47-0.70) for HAS-BLED and 0.64 (CI 0.51-0.76) for RIETE.

CONCLUSION

The Kuijer, HAS-BLED, and RIETE models in patients with VTE generally do not adequately estimate the risk of bleeding at three months, with a low ability to discriminate high-risk patients. Cautious interpretation is recommended until further evidence is available.

Reducing bleeding risk in patients on oral anticoagulation therapy

INTRODUCTION

Oral anticoagulation (OAC) significantly mitigates thromboembolism risks in atrial fibrillation (AF) and venous thromboembolism (VTE) patients yet concern about major bleeding events persist. In fact, clinically relevant hemorrhages can be life-threatening. Bleeding risk is dynamic and influenced by factors such as age, new comorbidities, and drug therapies, and should not be assessed solely based on static baseline factors.

AREAS COVERED

We comprehensively review the bleeding risk associated with OAC therapy. Emphasizing the importance of assessing both thromboembolic and bleeding risks, we present clinical tools for estimating stroke and systemic embolism (SSE) and bleeding risk in AF and VTE patients. We also address overlapping risk factors and the dynamic nature of bleeding risk.

EXPERT OPINION

The OAC management is undergoing constant transformation, motivated by the primary objective of mitigating thromboembolism and bleeding hazards, thereby amplifying patient safety throughout the course of treatment. The future of OAC embraces personalized approaches and innovative therapies, driven by advanced pathophysiological insights and technological progress. This holds promise for improving patient outcomes and revolutionizing anticoagulation practices.

Assessment and mitigation of bleeding risk in atrial fibrillation and venous thromboembolism: A Position Paper from the ESC Working Group on Thrombosis, in collaboration with the European Heart Rhythm Association, the Association for Acute CardioVascular Care and the Asia-Pacific Heart Rhythm Society

Whilst there is a clear clinical benefit of oral anticoagulation (OAC) in patients with atrial fibrillation (AF) and venous thromboembolism (VTE) in reducing the risks of thromboembolism, major bleeding events (especially intracranial bleeds) may still occur and be devastating. The decision to initiate and continue anticoagulation is often based on a careful assessment of both the thromboembolism and bleeding risk. The more common and validated bleeding risk factors have been used to formulate bleeding risk stratification scores, but thromboembolism and bleeding risk factors often overlap. Also, many factors that increase bleeding risk are transient and modifiable, such as variable international normalized ratio values, surgical procedures, vascular procedures, or drug-drug and food-drug interactions. Bleeding risk is also not a static 'one off' assessment based on baseline factors but is dynamic, being influenced by ageing, incident comorbidities, and drug therapies. In this Consensus Document, we comprehensively review the published evidence and propose a consensus on bleeding risk assessments in patients with AF and VTE, with the view to summarizing 'best practice' when approaching antithrombotic therapy in these patients. We address the epidemiology and size of the problem of bleeding risk in AF and VTE, review established bleeding risk factors, and summarize definitions of bleeding. Patient values and preferences, balancing the risk of bleeding against thromboembolism are reviewed, and the prognostic implications of bleeding are discussed. We propose consensus statements that may help to define evidence gaps and assist in everyday clinical practice.

The Gab2-MALT1 axis regulates thromboinflammation and deep vein thrombosis

Deep vein thrombosis (DVT) is the third most common cause of cardiovascular mortality. Several studies suggest that DVT occurs at the intersection of dysregulated inflammation and coagulation upon activation of inflammasome and secretion of interleukin 1β (IL-1β) in restricted venous flow conditions. Our recent studies showed a signaling adapter protein, Gab2 (Grb2-associated binder 2), plays a crucial role in propagating inflammatory signaling triggered by IL-1β and other inflammatory mediators in endothelial cells. The present study shows that Gab2 facilitates the assembly of the CBM (CARMA3 [CARD recruited membrane-associated guanylate kinase protein 3]-BCL-10 [B-cell lymphoma 10]-MALT1 [mucosa-associated lymphoid tissue lymphoma translocation protein 1]) signalosome, which mediates the activation of Rho and NF-κB in endothelial cells. Gene silencing of Gab2 or MALT1, the effector signaling molecule in the CBM signalosome, or pharmacological inhibition of MALT1 with a specific inhibitor, mepazine, significantly reduced IL-1β-induced Rho-dependent exocytosis of P-selectin and von Willebrand factor (VWF) and the subsequent adhesion of neutrophils to endothelial cells. MALT1 inhibition also reduced IL-1β-induced NF-κB-dependent expression of tissue factor and vascular cell adhesion molecule 1. Consistent with the in vitro data, Gab2 deficiency or pharmacological inhibition of MALT1 suppressed the accumulation of monocytes and neutrophils at the injury site and attenuated venous thrombosis induced by the inferior vena cava ligation-induced stenosis or stasis in mice. Overall, our data reveal a previously unrecognized role of the Gab2-MALT1 axis in thromboinflammation. Targeting the Gab2-MALT1 axis with MALT1 inhibitors may become an effective strategy to treat DVT by suppressing thromboinflammation without inducing bleeding complications.

Bleeding Risk Assessment in End-Stage Kidney Disease: Validation of Existing Risk Scores and Evaluation of a Machine Learning-Based Approach

BACKGROUND

 Patients with end-stage kidney disease (ESKD) on hemodialysis (HD) are at increased risk for bleeding. However, despite relevant clinical implications regarding dialysis modalities or anticoagulation, no bleeding risk assessment strategy has been established in this challenging population.

METHODS

 Analyses on bleeding risk assessment models were performed in the population-based Vienna InVestigation of Atrial fibrillation and thromboemboLism in patients on hemoDialysIs (VIVALDI) study including 625 patients. In this cohort study, patients were prospectively followed for a median observation period of 3.5 years for the occurrence of major bleeding. First, performances of existing bleeding risk scores (i.e., HAS-BLED, HEMORR2HAGES, ATRIA, and four others) were evaluated in terms of discrimination and calibration. Second, four machine learning-based prediction models that included clinical, dialysis-specific, and laboratory parameters were developed and tested using Monte Carlo cross-validation.

RESULTS

 Of 625 patients (median age: 66 years, 37% women), 89 (14.2%) developed major bleeding, with a 1-year, 2-year, and 3-year cumulative incidence of 6.1% (95% confidence interval [CI]: 4.2-8.0), 10.3% (95% CI: 8.0-12.8), and 13.5% (95% CI: 10.8-16.2), respectively. C-statistics of the seven contemporary bleeding risk scores ranged between 0.54 and 0.59 indicating poor discriminatory performance. The HAS-BLED score showed the highest C-statistic of 0.59 (95% CI: 0.53-0.66). Similarly, all four machine learning-based predictions models performed poorly in internal validation (C-statistics ranging from 0.49 to 0.55).

CONCLUSION

 Existing bleeding risk scores and a machine learning approach including common clinical parameters fail to assist in bleeding risk prediction of patients on HD. Therefore, new approaches, including novel biomarkers, to improve bleeding risk prediction in patients on HD are needed.

Assessment and Mitigation of Bleeding Risk in Atrial Fibrillation and Venous Thromboembolism: Executive Summary of a European and Asia-Pacific Expert Consensus Paper

While there is a clear clinical benefit of oral anticoagulation in patients with atrial fibrillation (AF) and venous thromboembolism (VTE) in reducing the risks of thromboembolism, major bleeding events (especially intracranial bleeds) may still occur and be devastating. The decision for initiating and continuing anticoagulation is often based on a careful assessment of both thromboembolism and bleeding risk. The more common and validated bleeding risk factors have been used to formulate bleeding risk stratification scores, but thromboembolism and bleeding risk factors often overlap. Also, many factors that increase bleeding risk are transient and modifiable, such as variable international normalized ratio values, surgical procedures, vascular procedures, or drug-drug and food-drug interactions. Bleeding risk is also not a static "one-off" assessment based on baseline factors but is dynamic, being influenced by aging, incident comorbidities, and drug therapies. In this executive summary of a European and Asia-Pacific Expert Consensus Paper, we comprehensively review the published evidence and propose a consensus on bleeding risk assessments in patients with AF and VTE, with a view to summarizing "best practice" when approaching antithrombotic therapy in these patients. We address the epidemiology and size of the problem of bleeding risk in AF and VTE, and review established bleeding risk factors and summarize definitions of bleeding. Patient values and preferences, balancing the risk of bleeding against thromboembolism, are reviewed, and the prognostic implications of bleeding are discussed. We propose consensus statements that may help to define evidence gaps and assist in everyday clinical practice.

Factor XI Inhibitors for Prevention and Treatment of Venous Thromboembolism: A Review on the Rationale and Update on Current Evidence

Although anticoagulation therapy has evolved from non-specific drugs (i.e., heparins and vitamin K antagonists) to agents that directly target specific coagulation factors (i.e., direct oral anticoagulants, argatroban, fondaparinux), thrombosis remains a leading cause of death worldwide. Direct oral anticoagulants (i.e., factor IIa- and factor Xa-inhibitors) now dominate clinical practice because of their favorable pharmacological profile and ease of use, particularly in venous thromboembolism (VTE) treatment and stroke prevention in atrial fibrillation. However, despite having a better safety profile than vitamin K antagonists, their bleeding risk is not insignificant. This is true for all currently available anticoagulants, and a high bleeding risk is considered a contraindication to anticoagulation. As a result, ongoing research focuses on developing future anticoagulants with an improved safety profile. Several promising approaches to reduce the bleeding risk involve targeting the intrinsic (or contact activation) pathway of coagulation, with the ultimate goal of preventing thrombosis without impairing hemostasis. Based on epidemiological data on hereditary factor deficiencies and preclinical studies factor XI (FXI) emerged as the most promising candidate target. In this review, we highlight unmet clinical needs of anticoagulation therapy, outlay the rationale and evidence for inhibiting FXI, discuss FXI inhibitors in current clinical trials, conduct an exploratory meta-analysis on their efficacy and safety, and provide an outlook on the potential clinical application of these novel anticoagulants.