Magnetic resonance venography to assess thrombus resolution with edoxaban monotherapy versus parenteral anticoagulation/warfarin for symptomatic deep vein thrombosis: A multicenter feasibility study

Evaluation of acute thrombus regression effect of edoxaban for deep vein thrombosis in patients with cancer: a single-center prospective observational study

BACKGROUND

Although there are reports on the recurrence prevention in the chronic phase using direct oral anticoagulants (DOACs) for deep vein thrombosis (DVT) in patients with cancer, acute thrombus regression effect using DOACs has not been assessed. This study aimed to assess the thrombus regression effect of initial treatment using edoxaban for acute lower-extremity DVT in patients with active cancer.

METHODS AND RESULTS

In this observational study, among the inpatients with cancer and lower-extremity DVT who underwent initial treatment with edoxaban at our hospital from November 2019 to December 2021, 34 consenting patients were recruited in this study. The quantitative ultrasound thrombus (QUT) score of thrombus volume was calculated at baseline (before administration) and 7-14 days after the start of edoxaban administration, using lower-extremity venous ultrasound to evaluate changes in thrombus volume. The primary and secondary endpoints were the acute thrombus regression effect of edoxaban and the impact of patients' clinical frailty on the thrombus regression effect, respectively. Anticoagulant therapy with edoxaban significantly reduced QUT score (p < 0.001). In addition, regardless of the Clinical Frailty Scale scores, QUT score decreased significantly.

CONCLUSION

Initial treatment with edoxaban was effective for lower-extremity DVT in patients with cancer. In addition, the effect was the same independent of the degree of frailty.

The effect of ultrasound-assisted thrombolysis studied in blood-on-a-chip

BACKGROUND

Thromboembolism, which leads to pulmonary embolism and ischemic stroke, remains one of the main causes of death. Ultrasound-assisted thrombolysis (UAT) is an effective thrombolytic method. However, further studies are required to elucidate the mechanism of ultrasound on arterial and venous thrombi.

METHODS

We employed the blood-on-a-chip technology to simulate thrombus formation in coronary stenosis and deep vein valves. Subsequently, UAT was conducted on the chip to assess the impact of ultrasound on thrombolysis under varying flow conditions. Real-time fluorescence was used to assess thrombolysis and drug penetration. Finally, scanning electron microscopy and immunofluorescence were used to determine the effect of ultrasound on fibrinolysis.

RESULTS

The study revealed that UAT enhanced the thrombolytic rate by 40% in the coronary stenosis chip and by 10% in the deep venous valves chip. This enhancement is attributed to the disruption of crosslinked fibrin fibers by ultrasound, leading to increased urokinase diffusion within the thrombus and accumulation of plasminogen on the fibrinogen α chain. Moreover, the acceleration of the dissolution rate of thrombi in the venous valve chip by ultrasound was not as significant as that in the coronary stenosis chip.

CONCLUSION

These findings highlight the differential impact of ultrasound on thrombolysis under various flow conditions and emphasize the valuable role of the blood-on-a-chip technology in exploring thrombolysis mechanisms.

Oral direct thrombin inhibitors or oral factor Xa inhibitors versus conventional anticoagulants for the treatment of deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a condition in which a clot forms in the deep veins, most commonly of the leg. It occurs in approximately one in 1000 people. If left untreated, the clot can travel up to the lungs and cause a potentially life-threatening pulmonary embolism (PE). Previously, a DVT was treated with the anticoagulants heparin and vitamin K antagonists. However, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTIs) and oral factor Xa inhibitors, which have characteristics that may be favourable compared to conventional treatment, including oral administration, a predictable effect, lack of frequent monitoring or dose adjustment and few known drug interactions. DOACs are now commonly being used for treating DVT: recent guidelines recommended DOACs over conventional anticoagulants for both DVT and PE treatment. This Cochrane Review was first published in 2015. It was the first systematic review to measure the effectiveness and safety of these drugs in the treatment of DVT. This is an update of the 2015 review.  OBJECTIVES: To assess the effectiveness and safety of oral DTIs and oral factor Xa inhibitors versus conventional anticoagulants for the long-term treatment of DVT.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 1 March 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which people with a DVT, confirmed by standard imaging techniques, were allocated to receive an oral DTI or an oral factor Xa inhibitor compared with conventional anticoagulation or compared with each other for the treatment of DVT.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were recurrent venous thromboembolism (VTE), recurrent DVT and PE. Secondary outcomes included all-cause mortality, major bleeding, post-thrombotic syndrome (PTS) and quality of life (QoL). We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified 10 new studies with 2950 participants for this update. In total, we included 21 RCTs involving 30,895 participants. Three studies investigated oral DTIs (two dabigatran and one ximelagatran), 17 investigated oral factor Xa inhibitors (eight rivaroxaban, five apixaban and four edoxaban) and one three-arm trial investigated both a DTI (dabigatran) and factor Xa inhibitor (rivaroxaban). Overall, the studies were of good methodological quality. Meta-analysis comparing DTIs to conventional anticoagulation showed no clear difference in the rate of recurrent VTE (odds ratio (OR) 1.17, 95% confidence interval (CI) 0.83 to 1.65; 3 studies, 5994 participants; moderate-certainty evidence), recurrent DVT (OR 1.11, 95% CI 0.74 to 1.66; 3 studies, 5994 participants; moderate-certainty evidence), fatal PE (OR 1.32, 95% CI 0.29 to 6.02; 3 studies, 5994 participants; moderate-certainty evidence), non-fatal PE (OR 1.29, 95% CI 0.64 to 2.59; 3 studies, 5994 participants; moderate-certainty evidence) or all-cause mortality (OR 0.66, 95% CI 0.41 to 1.08; 1 study, 2489 participants; moderate-certainty evidence). DTIs reduced the rate of major bleeding (OR 0.58, 95% CI 0.38 to 0.89; 3 studies, 5994 participants; high-certainty evidence).   For oral factor Xa inhibitors compared with conventional anticoagulation, meta-analysis demonstrated no clear difference in recurrent VTE (OR 0.85, 95% CI 0.71 to 1.01; 13 studies, 17,505 participants; moderate-certainty evidence), recurrent DVT (OR 0.70, 95% CI 0.49 to 1.01; 9 studies, 16,439 participants; moderate-certainty evidence), fatal PE (OR 1.18, 95% CI 0.69 to 2.02; 6 studies, 15,082 participants; moderate-certainty evidence), non-fatal PE (OR 0.93, 95% CI 0.68 to 1.27; 7 studies, 15,166 participants; moderate-certainty evidence) or all-cause mortality (OR 0.87, 95% CI 0.67 to 1.14; 9 studies, 10,770 participants; moderate-certainty evidence). Meta-analysis showed a reduced rate of major bleeding with oral factor Xa inhibitors compared with conventional anticoagulation (OR 0.63, 95% CI 0.45 to 0.89; 17 studies, 18,066 participants; high-certainty evidence).  AUTHORS' CONCLUSIONS: The current review suggests that DOACs may be superior to conventional therapy in terms of safety (major bleeding), and are probably equivalent in terms of efficacy. There is probably little or no difference between DOACs and conventional anticoagulation in the prevention of recurrent VTE, recurrent DVT, pulmonary embolism and all-cause mortality. DOACs reduced the rate of major bleeding compared to conventional anticoagulation. The certainty of evidence was moderate or high.

Comparative Risks of Fracture Among Direct Oral Anticoagulants and Warfarin: A Systematic Review and Network Meta-Analysis

Importance

Previous studies have shown the effectiveness and safety of direct oral anticoagulants (DOACs), including lower fracture risks, compared to warfarin. However, direct or indirect comparisons between different DOACs are scarce in the literature.

Objective

This study aims to compare fracture risks among different DOACs and warfarin, including apixaban, rivaroxaban, dabigatran, and edoxaban, in patients with non-valvular atrial fibrillation (NVAF) or venous thromboembolism (VTE).

Methods

We searched PubMed/MEDLINE, Embase, Cochrane CENTRAL, and Web of Science for randomized controlled trials and cohort studies comparing the fracture risks among patients who used warfarin or DOACs, up to March 2021. Two authors extracted data and appraised the risk of bias of included studies. The primary outcome was fracture risk. We performed pairwise meta-analyses to compare differences between medications and network meta-analyses using frequentist random-effects models to compare through indirect evidence. We used surface under the cumulative ranking curve (SUCRA) and mean ranks to determine the probability of a DOAC ranking best in terms of fracture risk.

Results

Thirty-one studies were included in the final analysis. Twenty-four randomized controlled trials and seven cohort studies with 455,343 patients were included in the systematic review and network meta-analysis. Compared to warfarin, the risk of any fractures was lowest with apixaban [relative risk (RR) = 0.59; 95% confidence interval (CI): 0.48-0.73], followed by rivaroxaban (RR: 0.72; 95% CI: 0.60-0.86), edoxaban (RR: 0.88; 95% CI: 0.62-1.23), and dabigatran (RR = 0.90; 95% CI: 0.75-1.07). No substantial inconsistency between direct and indirect evidence was detected for all outcomes.

Conclusions

All DOACs were safer than warfarin concerning the risk of fracture; however, apixaban had the lowest relative risk of fracture within the class of DOACs. Further head-to-head prospective studies should confirm the comparative safety profiles of DOACs regarding fractures.

ERS statement on chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism, either symptomatic or not. The occlusion of proximal pulmonary arteries by fibrotic intravascular material, in combination with a secondary microvasculopathy of vessels <500 µm, leads to increased pulmonary vascular resistance and progressive right heart failure. The mechanism responsible for the transformation of red clots into fibrotic material remnants has not yet been elucidated. In patients with pulmonary hypertension, the diagnosis is suspected when a ventilation/perfusion lung scan shows mismatched perfusion defects, and confirmed by right heart catheterisation and vascular imaging. Today, in addition to lifelong anticoagulation, treatment modalities include surgery, angioplasty and medical treatment according to the localisation and characteristics of the lesions.This statement outlines a review of the literature and current practice concerning diagnosis and management of CTEPH. It covers the definitions, diagnosis, epidemiology, follow-up after acute pulmonary embolism, pathophysiology, treatment by pulmonary endarterectomy, balloon pulmonary angioplasty, drugs and their combination, rehabilitation and new lines of research in CTEPH.It represents the first collaboration of the European Respiratory Society, the International CTEPH Association and the European Reference Network-Lung in the pulmonary hypertension domain. The statement summarises current knowledge, but does not make formal recommendations for clinical practice.

Fracture Risks in Patients Treated With Different Oral Anticoagulants: A Systematic Review and Meta-Analysis

Background Evidence on the differences in fracture risk associated with non-vitamin K antagonist oral anticoagulants (NOAC) and warfarin is inconsistent and inconclusive. We conducted a systematic review and meta-analysis to assess the fracture risk associated with NOACs and warfarin. Methods and Results We searched PubMed, Embase, Cochrane Library, Scopus, Web of Science, and ClinicalTrials.gov from inception until May 19, 2020. We included studies presenting measurements (regardless of primary/secondary/tertiary/safety outcomes) for any fracture in both NOAC and warfarin users. Two or more reviewers independently screened relevant articles, extracted data, and performed quality assessments. Data were retrieved to synthesize the pooled relative risk (RR) of fractures associated with NOACs versus warfarin. Random-effects models were used for data synthesis. We included 29 studies (5 cohort studies and 24 randomized controlled trials) with 388 209 patients. Patients treated with NOACs had lower risks of fracture than those treated with warfarin (pooled RR, 0.84; 95% CI, 0.77-0.91; P<0.001) with low heterogeneity (I²=38.9%). NOACs were also associated with significantly lower risks of hip fracture than warfarin (pooled RR, 0.89; 95% CI, 0.81-0.98; P=0.023). A nonsignificant trend of lower vertebral fracture risk in NOAC users was also observed (pooled RR, 0.74; 95% CI, 0.54-1.01; P=0.061). Subgroup analyses for individual NOACs demonstrated that dabigatran, rivaroxaban, and apixaban were significantly associated with lower fracture risks. Furthermore, the data synthesis results from randomized controlled trials and real-world cohort studies were quite consistent, indicating the robustness of our findings. Conclusions Compared with warfarin, NOACs are associated with lower risks of bone fracture.

American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), occurs in ∼1 to 2 individuals per 1000 each year, corresponding to ∼300 000 to 600 000 events in the United States annually.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support patients, clinicians, and others in decisions about treatment of VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and adult patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 28 recommendations for the initial management of VTE, primary treatment, secondary prevention, and treatment of recurrent VTE events.

CONCLUSIONS

Strong recommendations include the use of thrombolytic therapy for patients with PE and hemodynamic compromise, use of an international normalized ratio (INR) range of 2.0 to 3.0 over a lower INR range for patients with VTE who use a vitamin K antagonist (VKA) for secondary prevention, and use of indefinite anticoagulation for patients with recurrent unprovoked VTE. Conditional recommendations include the preference for home treatment over hospital-based treatment for uncomplicated DVT and PE at low risk for complications and a preference for direct oral anticoagulants over VKA for primary treatment of VTE.

Risk of Major Gastrointestinal Bleeding With New vs Conventional Oral Anticoagulants: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

There is controversy over whether use of non-vitamin K antagonist oral anticoagulants (NOACs) associates with increased risk of major gastrointestinal bleeding (GIB) compared with conventional therapies (such as vitamin K antagonists or anti-platelet agents). We performed a systematic review and meta-analysis of data from randomized controlled trials and high-quality real-world studies.

METHODS

We performed a systematic search of the MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov Website databases (through Oct 12, 2018) for randomized controlled trials and high-quality real-world studies that reported major GIB events in patients given NOACs or conventional therapy. Relative risks (RRs) for randomized controlled trials and adjusted hazard ratios (aHRs) for real-world studies were calculated separately using random-effects models.

RESULTS

We analyzed data from 43 randomized controlled trials (183,752 patients) and 41 real-world studies (1,879,428 patients). The pooled major rates of GIB for patients on NOACs (1.19%) vs conventional treatment (0.92%) did not differ significantly (RR from randomized controlled trials, 1.09; 95% CI, 0.91-1.31 and aHR from real-world studies, 1.02; 95% CI, 0.94-1.10; P_interaction=.52). Rivaroxaban, but not other NOACs, was associated with an increased risk for major GIB (RR from randomized controlled trials, 1.39; 95% CI, 1.17-1.65 and aHR from real-world studies, 1.14; 95% CI, 1.04-1.23; P_interaction = .06). Analyses of subgroups, such as patients with different indications, dosage, or follow-up time, did not significantly affect results. Meta-regression analysis failed to detect any potential confounding to impact the primacy outcome.

CONCLUSIONS

In a systematic review and meta-analysis of data from randomized controlled trials and real-world studies, we confirmed that there is no significant difference in risk of major GIB between patients receiving NOACs vs conventional treatment. Rivaroxaban users had a 39% increase in risk for major GIB.

Combined effect of a direct oral anticoagulant edoxaban and an inhibitor of activated thrombin-activatable fibrinolysis inhibitor on clot lysis

Fibrinolysis is regulated by the thrombin/thrombin-activatable fibrinolysis inhibitor (TAFI) system. Thus, anticoagulants and inhibitors of TAFI are expected to accelerate fibrinolysis. The combined effects of an anticoagulant and a TAFIa inhibitor on fibrinolysis remain unknown. The aim of this study was to evaluate the combined effect of edoxaban, an oral direct factor Xa (FXa) inhibitor, and a TAFIa inhibitor, potato tuber carboxypeptidase inhibitor (PCI) on tissue-type plasminogen activator (t-PA)-induced clot lysis in human plasma in vitro. Pooled human plasma (containing 180 ng/mL t-PA and 0.1 nM thrombomodulin) was mixed with edoxaban and/or PCI. Clot formation was induced by 2.5 pM tissue factor and 4 µM phospholipids and clot lysis time was examined. Plasma plasmin-α2 antiplasmin complex (PAP) concentration was measured as a marker of plasmin generation. Edoxaban or PCI alone significantly shortened the t-PA-induced clot lysis time and plasma PAP concentration. The combination of these compounds significantly accelerated the clot lysis compared with the inhibitors alone. Addition of PCI (0.3, 1, and 3 μg/mL) to 75 ng/mL edoxaban increased plasma PAP concentration compared with edoxaban alone; however, compared with PCI alone only the combination of 0.3 μg/mL PCI + 75 ng/mL edoxaban showed the significant increase in PAP concentration. Concomitant use of an oral direct FXa inhibitor, edoxaban, and a TAFIa inhibitor, PCI, significantly accelerate fibrinolysis via enhancement of plasmin generation. These results suggest that the combination of edoxaban and a TAFIa inhibitor might be beneficial for the treatment of thromboembolic diseases.

Edoxaban improves atrial fibrillation and thromboembolism through regulation of the Wnt-β-induced PI3K/ATK-activated protein C system

Thromboembolism is a commonly observed condition in geriatrics that is caused by vascular endothelial injury, platelet activation, physiological coagulation processes, reduction of anticoagulant activity, decreased fibrinolytic activity and abnormal flow in the heart chamber, artery or vein. The protein C anticoagulant system serves a crucial role in anticoagulant therapy for the treatment of thromboembolism. Previous findings have suggested that edoxaban is an efficient oral anticoagulant in the acute treatment of venous thromboembolism. In the present study, the efficacy of edoxaban on thromboembolism induced by atrial fibrillation was investigated in a mouse model. Inflammatory factors interleukin (IL)-1, −4, −8 and tumor necrosis factor (TNF)-α were analyzed in the sera of mice with fibrillation induced by thromboembolism. Expression and activity of thymic stromal lymphopoietin (TSLP) and activated protein C resistance were investigated in platelets and vascular endothelial cells (VECs). TSLP-induced platelet viability, Wnt-β phosphorylation and integrin expression were analyzed in platelets. Furthermore, Wnt-β expression and the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway in VECs were analyzed. Results demonstrated that the expression levels of IL-1, −4, −8 and TNF-α were significantly downregulated in the sera of mice with fibrillation and thromboembolism following treatment with edoxaban (P<0.01). Furthermore, the expression levels of prostacyclin (PGI2), prostaglandin (PG)E2, PGD2 and PGF2α were significantly increased in the sera of experimental mice that received edoxaban therapy (P<0.01). Results also indicated that edoxaban significantly stimulated the protein expression of TSLP and activated Wnt-β phosphorylation and integrin expression in platelets (P<0.01). In addition, edoxaban therapy significantly upregulated the expression levels of PI3K and AKT, and subsequently increased the activity of protein C and S in VECs (P<0.01). Notably, edoxaban treatment improved atrial fibrillation and thromboembolism, as determined by pathological analysis. In conclusion, these results suggested that edoxaban elicited beneficial effects for mice with atrial fibrillation induced by thromboembolism through the regulation of the Wnt-β-induced PI3K/ATK-activated protein C system.

Can thrombus age guide thrombolytic therapy?

Venous thrombosis (VT) is a common yet complex clinical condition that has shown minimal alteration in clinical management for decades. It is well known that thrombus evolves structurally over time, with complex changes resulting from the interplay between coagulation factors, cytokines, leukocytes and a myriad of other factors. Our current treatment options are most effective in the acute thrombus, which is composed predominantly of a loose mesh of fibrin and red blood cells (RBCs), making current anticoagulation therapies and thrombolytics quite effective in treatment. Later stages of thrombus are more cellular containing leukocytes, and develop a fibrotic collagenous framework that is more resistant to our current treatments. Understanding the biology of an evolving thrombus will allow us to tailor our treatment and optimize outcomes, as well as focus on novel therapies for the treatment of chronic thrombus. Given the morbidity and mortality of both post thrombotic syndrome (PTS) in patients with deep VT, as well as chronic thromboembolic pulmonary hypertension (CTEPH) in patients with pulmonary embolism (PE), new and innovative therapies must continue to be explored to help prevent these potentially devastating conditions.