Treatment of patients with acute deep vein thrombosis and/or pulmonary embolism: efficacy and safety of non-VKA oral anticoagulants in selected populations

Safety of the pulmonary embolism rule-out criteria rule: Findings from the Registro Informatizado de la Enfermedad TromboEmbolica venosa (RIETE) registry

BACKGROUND

The diagnostic strategy for pulmonary embolism (PE) includes a D-dimer test when PE probability is low or intermediate, but false-positive D-dimer results are frequent and can result in an unnecessary computed tomography pulmonary angiogram. The PE rule-out criteria (PERC) rule excludes PE without D-dimer testing when pretest probability is <15%. The aim of this study was to assess the safety of the PERC rule strategy in patients included in the Registro Informatizado de la Enfermedad TromboEmbolica venosa (RIETE) registry.

METHODS

This retrospective cohort study used data from the RIETE registry, an ongoing, international prospective registry of patients with objectively confirmed venous thromboembolism. The primary outcome was the failure rate of the PERC strategy, represented by the proportion of PERC-negative (PERC-N) patients with a PE included in the registry. Secondary outcomes were a comparison of the clinical characteristics, treatment strategy, and outcome of PERC-N versus PERC-positive (PERC-P) patients at 3 months.

RESULTS

From 2001 to 2021, a total of 49,793 patients with acute PE were enrolled in the RIETE registry. We included 48,903 in the final analysis after exclusion of 890 patients with an undetermined PERC status. Only 346 patients were PERC-N with a failure rate of 0.7% (95% confidence interval 0.6%-0.8%). PERC-N patients presented more frequently with chest pain but less often with dyspnea, syncope, or hypotension. They also had subsegmental or segmental PE more frequently, were more often treated with direct oral anticoagulants, and received mechanical or pharmacological thrombolysis less often. In addition, PERC-N patients had a lower incidence of recurrent deep vein thrombosis, major bleeding, and death attributed to PE during the 3-month follow-up.

CONCLUSIONS

A low failure rate of the PERC rule was observed in the RIETE registry, thus supporting its use to safely identify patients with an unlikely probability of PE.

Oral direct thrombin inhibitors or oral factor Xa inhibitors versus conventional anticoagulants for the treatment of pulmonary embolism

BACKGROUND

Pulmonary embolism (PE) is a potentially life-threatening condition in which a clot can migrate from the deep veins, most commonly in the leg, to the lungs. Conventional treatment of PE used unfractionated heparin (UFH), low molecular weight heparin (LMWH), fondaparinux, and vitamin K antagonists (VKAs). Recently, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTIs) and oral factor Xa inhibitors. DOACs have characteristics that may be favourable to conventional treatment, including oral administration, a predictable effect, no need for frequent monitoring or re-dosing, and few known drug interactions. This review reports the efficacy and safety of these drugs in the long-term treatment of PE (minimum duration of three months). This is an update of a Cochrane Review first published in 2015.  OBJECTIVES: To assess the efficacy and safety of oral DTIs and oral factor Xa inhibitors versus conventional anticoagulants for the long-term treatment of PE.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases, the World Health Organization International Clinical Trials Registry Platform and the ClinicalTrials.gov trials registers to 2 March 2022. We checked the reference lists of relevant articles for additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which people with a PE confirmed by standard imaging techniques were allocated to receive an oral DTI or an oral factor Xa inhibitor compared with a conventional anticoagulant or compared with each other for the long-term treatment of PE (minimum duration three months).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were recurrent PE, recurrent venous thromboembolism (VTE), and deep vein thrombosis (DVT). Secondary outcomes were all-cause mortality, major bleeding, and health-related quality of life. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified five additional RCTs with 1484 participants for this update. Together with the previously included trials, we have included ten RCTs with a total of 13,073 participants. Two studies investigated an oral DTI (dabigatran) and eight studies investigated oral factor Xa inhibitors (three rivaroxaban, three apixaban, and two edoxaban). The studies were of good methodological quality overall.  Meta-analysis showed no clear difference in the efficacy and safety of oral DTI compared with conventional anticoagulation in preventing recurrent PE (odds ratio (OR) 1.02, 95% confidence interval (CI) 0.50 to 2.04; 2 studies, 1602 participants; moderate-certainty evidence), recurrent VTE (OR 0.93, 95% CI 0.52 to 1.66; 2 studies, 1602 participants; moderate-certainty evidence), DVT (OR 0.79, 95% CI 0.29 to 2.13; 2 studies, 1602 participants; moderate-certainty evidence), and major bleeding (OR 0.50, 95% CI 0.15 to 1.68; 2 studies, 1527 participants; moderate-certainty evidence). We downgraded the certainty of evidence by one level for imprecision due to the low number of events. There was also no clear difference between the oral factor Xa inhibitors and conventional anticoagulation in the prevention of recurrent PE (OR 0.92, 95% CI 0.66 to 1.29; 3 studies, 8186 participants; moderate-certainty evidence), recurrent VTE (OR 0.83, 95% CI 0.66 to 1.03; 8 studies, 11,416 participants; moderate-certainty evidence), DVT (OR 0.77, 95% CI 0.48 to 1.25; 2 studies, 8151 participants; moderate-certainty evidence), all-cause mortality (OR 1.16, 95% CI 0.79 to 1.70; 1 study, 4817 participants; moderate-certainty evidence) and major bleeding (OR 0.71, 95% CI 0.36 to 1.41; 8 studies, 11,447 participants; low-certainty evidence); the heterogeneity for major bleeding was significant (I2 = 79%). We downgraded the certainty of the evidence to moderate and low because of imprecision due to the low number of events and inconsistency due to clinical heterogeneity. None of the included studies measured health-related quality of life.

AUTHORS' CONCLUSIONS

Available evidence shows there is probably little or no difference between DOACs and conventional anticoagulation in the prevention of recurrent PE, recurrent VTE, DVT, all-cause mortality, and major bleeding. The certainty of evidence was moderate or low. Future large clinical trials are required to identify if individual drugs differ in effectiveness and bleeding risk, and to explore effect differences in subgroups, including people with cancer and obesity.

Downregulation of interleukin-6 and C-reactive protein underlies a novel inhibitory role of microRNA-136-5p in acute lower extremity deep vein thrombosis

Deep vein thrombosis (DVT) comprises a critical and common health condition with high incidence, mortality, and long-term adverse sequelae. Several differentially expressed microRNAs (miRNAs) have emerged as promising prognostic markers in DVT. The present study intended to explore the functional relevance of miR-136-5p in acute lower extremity DVT (LEDVT). Rat models of acute LEDVT were established and miR-136-5p expression was altered by agomir or antagomir to assess its effects. In addition, in vitro gain- and loss-experiments, prior to exposure to CoCl₂, were performed to investigate effects of miR-136-5p on human umbilical vein endothelial cell (HUVEC) apoptosis and levels of interleukin-6 (IL-6) and C-reactive protein (CRP). miR-136-5p was downregulated, whereas IL-6 and CRP were elevated in acute LEDVT patients. Notably, miR-136-5p was confirmed to target both IL-6 and CRP. Overexpression of miR-136-5p led to reduced length, weight, and ratio of weight to length of the venous thrombus. Furthermore, overexpressed miR-136-5p downregulated the expression of IL-6 and CRP, consequently inhibiting HUVEC apoptosis. Conjointly, our data indicate that the overexpression of miR-136-5p has the potential to bind to the 3’-UTR in the mRNAs for IL-6 and CRP and mitigate acute LEDVT, which provides a basis for new therapeutic targets in acute LEDVT treatment.

The risk of post-thrombotic syndrome in patients with proximal deep vein thrombosis treated with the direct oral anticoagulants

The novel direct oral anticoagulants (DOAC) have been shown to be at least as effective as and safer than conventional anticoagulants for the initial and long-term treatment of venous thromboembolic disorders. However, the rate of post-thrombotic syndrome (PTS) in patients with deep-vein thrombosis (DVT) treated with the DOACs is unknown. With the adoption of the Villalta scale, we assessed the rate of PTS at the end of the follow-up period in a consecutive series of 309 outpatients with acute proximal DVT who had received at least 3 months of treatment with a DOAC and had been followed-up for up to 3 years. The rate of PTS development was compared with that recorded in a historical cohort of 1036 consecutive patients who had been treated with vitamin K antagonists (VKA) and had received a similar follow-up examination. Logistic regression analysis, including propensity scoring to adjust for differing probabilities of undergoing VKA/DOAC, was used to identify predictors of PTS. PTS developed in 87 patients (28.2%) treated with the DOACs (severe in 12), and in 443 patients (42.8%) treated with VKAs (severe in 61). After adjusting for estimated propensity score, age, gender, concomitant symptoms of pulmonary embolism, duration of anticoagulation and development of residual vein thrombosis, the risk of PTS in the DOAC-treated patients was reduced by 54% in comparison to patients treated with conventional anticoagulation (odds ratio 0.46; 95% CI 0.33 to 0.63). We conclude that in comparison to VKAs, the use of the direct oral anticoagulants has the potential to offer a more favorable prognosis in terms of PTS development.

Ocular Myasthenia Induced by Rivaroxaban in Patient with Deep Vein Thrombosis

The non-vitamin K antagonist oral anticoagulant rivaroxaban is indicated in prevention and treatment of venous thromboembolism (VTE). A 60-year-old male patient complained of bilateral ptosis after administration of rivaroxaban for deep vein thrombosis (DVT). Myasthenia gravis (MG) was confirmed by positive serum antiacetylcholine receptor antibody test. No mediastinal thymoma was found. The ocular myasthenia reversed after discontinuing rivaroxaban treatment. Nevertheless, ptosis recurred and chronic oral pyridostigmine bromide treatment was necessary. The mechanism of MG development by rivaroxaban therapy is not completely understood. The development of rivaroxaban-induced autoimmune disease could be based on cross-reactivity between antibodies against rivaroxaban-derived antigens or by T-cell activation. To our knowledge, this report of ocular myasthenia by rivaroxaban administration is the first in the literature. Despite the benefits of rivaroxaban, it is important to recognize unexpected immune-related adverse events.

Secondary prevention of recurrent venous thromboembolism after initial oral anticoagulation therapy in patients with unprovoked venous thromboembolism

BACKGROUND

Currently, little evidence is available on the length and type of anticoagulation used for extended treatment for prevention of recurrent venous thromboembolism (VTE) in patients with unprovoked VTE who have completed initial oral anticoagulation therapy.

OBJECTIVES

To compare the efficacy and safety of available oral therapeutic options (aspirin, warfarin, direct oral anticoagulants (DOACs)) for extended thromboprophylaxis in adults with a first unprovoked VTE, to prevent VTE recurrence after completion of an acceptable initial oral anticoagulant treatment period, as defined in individual studies.

SEARCH METHODS

For this review, the Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (March 2017) as well as the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 2). We also searched trials registries (March 2017) and reference lists of relevant articles.

SELECTION CRITERIA

We included randomised controlled trials in which patients with a first, symptomatic, objectively confirmed, unprovoked VTE, who had been initially treated with anticoagulants, were randomised to extended prophylaxis (vitamin K antagonists (VKAs), antiplatelet agents, or DOACs) versus no prophylaxis or placebo. We also included trials that compared one type of extended prophylaxis versus another type of extended prophylaxis.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed quality, and extracted data. We resolved disagreements by discussion.

MAIN RESULTS

Six studies with a combined total of 3436 participants met the inclusion criteria. Five studies compared extended prophylaxis versus placebo: three compared warfarin versus placebo, and two compared aspirin versus placebo. One study compared one type of extended prophylaxis (rivaroxaban) versus another type of extended prophylaxis (aspirin). For extended prophylaxis versus placebo, we downgraded the quality of the evidence for recurrent VTE and all-cause mortality to moderate owing to concerns arising from risks of selection and performance bias in individual studies. For all other outcomes in this review, we downgraded the quality of the evidence to low owing to concerns arising from risk of bias for the studies stated above, combined with concerns over imprecision. For extended prophylaxis versus other extended prophylaxis, we downgraded the quality of the evidence for recurrent VTE and major bleeding to moderate owing to concerns over imprecision. Risk of bias in the individual study was low.Meta-analysis showed that extended prophylaxis was no more effective than placebo in preventing VTE-related mortality (odds ratio (OR) 0.98, 95% confidence interval (CI) 0.14 to 6.98; 1862 participants; 4 studies; P = 0.98; low-quality evidence), recurrent VTE (OR 0.63, 95% CI 0.38 to 1.03; 2043 participants; 5 studies; P = 0.07; moderate-quality evidence), major bleeding (OR 1.84, 95% CI 0.87 to 3.85; 2043 participants; 5 studies; P = 0.86; low-quality evidence), all-cause mortality (OR 1.00, 95% CI 0.63 to 1.57; 2043 participants; 5 studies; P = 0.99; moderate-quality evidence), clinically relevant non-major bleeding (OR 1.78, 95% CI 0.59 to 5.33; 1672 participants; 4 studies; P = 0.30; low-quality evidence), stroke (OR 1.15, 95% CI 0.39 to 3.46; 1224 participants; 2 studies; P = 0.80; low-quality evidence), or myocardial infarction (OR 1.00, 95% CI 0.35 to 2.87; 1495 participants; 3 studies; P = 1.00; low-quality evidence).One study showed that the novel oral anticoagulant rivaroxaban was associated with fewer recurrent VTEs than aspirin (OR 0.28, 95% CI 0.15 to 0.54; 1389 participants; P = 0.0001; moderate-quality evidence). Data show no clear differences in the incidence of major bleeding between rivaroxaban and aspirin (OR 3.06, 95% CI 0.37 to 25.51; 1389 participants; P = 0.30; moderate-quality evidence) nor in the incidence of clinically relevant non-major bleeding (OR 0.84, 95% CI 0.37 to 1.94; 1389 participants; 1 study; P = 0.69; moderate-quality evidence). Data on VTE-related mortality, all-cause mortality, stroke, and myocardial infarction were not yet available for participants with unprovoked VTE and will be incorporated in future versions of the review.

AUTHORS' CONCLUSIONS

Evidence is currently insufficient to permit definitive conclusions concerning the effectiveness and safety of extended thromboprophylaxis in prevention of recurrent VTE after initial oral anticoagulation therapy among participants with unprovoked VTE. Additional good-quality large-scale randomised controlled trials are required before firm conclusions can be reached.

ANMCO Position Paper: the use of non-vitamin K dependent new oral anticoagulant(s) in pulmonary embolism therapy and prevention

The new oral anticoagulants (NOACs) have radically changed the approach to the treatment and prevention of thromboembolic pulmonary embolism. The authors of this position paper face, in succession, issues concerning NOACs, including (i) their mechanism of action, pharmacodynamics, and pharmacokinetics; (ii) the use in the acute phase with the 'double drug single dose' approach or with 'single drug double dose'; (iii) the use in the extended phase with demonstrated efficacy and with low incidence of bleeding events; (iv) the encouraging use of NOACs in particular subgroups of patients such as those with cancer, the ones under- or overweight, with renal insufficiency (creatinine clearance > 30 mL/min), the elderly (>75 years); (v) they propose a possible laboratory clinical pathway for follow-up; and (vi) carry out an examination on the main drug interactions, their potential bleeding risk, and the way to deal with some bleeding complications. The authors conclude that the use of NOACs both in the acute phase and in the extended phase is equally effective to conventional therapy and associated with fewer major bleeding events, which make their use in patients at higher risk of recurrences safer.

Edoxaban in venous thromboembolism and stroke prevention: an appraisal

Oral anticoagulation is the therapeutic cornerstone in preventing thromboembolic risk in both atrial fibrillation (AF) and venous thromboembolism (VTE). After decades of the sole therapeutic oral anticoagulation option being warfarin, the introduction of non-vitamin K antagonist oral anticoagulants has heralded a new era. Edoxaban is the latest addition to these available for clinical use. Edoxaban was as effective and safer than warfarin in preventing thromboembolic risk in AF patients. Similarly, edoxaban effectiveness and safety was evident when treating VTE patients to prevent recurrent VTE or VTE-related death. Therefore, edoxaban represents a valuable alternative in treating thromboembolic risk for AF and VTE patients.

Oral direct thrombin inhibitors or oral factor Xa inhibitors for the treatment of pulmonary embolism

BACKGROUND

Pulmonary embolism is a potentially life-threatening condition in which a clot can travel from the deep veins, most commonly in the leg, up to the lungs. Previously, a pulmonary embolism was treated with the anticoagulants heparin and vitamin K antagonists. Recently, however, two forms of direct oral anticoagulants (DOACs) have been developed: oral direct thrombin inhibitors (DTI) and oral factor Xa inhibitors. The new drugs have characteristics that may be favourable over conventional treatment, including oral administration, a predictable effect, lack of frequent monitoring or re-dosing and few known drug interactions. To date, no Cochrane review has measured the effectiveness and safety of these drugs in the long-term treatment (minimum duration of three months) of pulmonary embolism.

OBJECTIVES

To assess the effectiveness of oral DTIs and oral factor Xa inhibitors for the long-term treatment of pulmonary embolism.

SEARCH METHODS

The Cochrane Vascular Trials Search Co-ordinator searched the Specialised Register (last searched January 2015) and the Cochrane Register of Studies (last searched January 2015). Clinical trials databases were also searched for details of ongoing or unpublished studies. We searched the reference lists of relevant articles retrieved by electronic searches for additional citations.

SELECTION CRITERIA

We included randomised controlled trials in which patients with a pulmonary embolism confirmed by standard imaging techniques were allocated to receive an oral DTI or an oral factor Xa inhibitor for the long-term (minimum duration three months) treatment of pulmonary embolism.

DATA COLLECTION AND ANALYSIS

Two review authors (LR, JM) independently extracted the data and assessed the risk of bias in the trials. Any disagreements were resolved by discussion with the third author (PK). We used meta-analyses when we considered heterogeneity low. The two primary outcomes were recurrent venous thromboembolism and pulmonary embolism. Other outcomes included all-cause mortality and major bleeding. We calculated all outcomes using an odds ratio (OR) with a 95% confidence interval (CI).

MAIN RESULTS

We included five randomised controlled trials with a total of 7897 participants. Two studies tested oral DTIs (dabigatran) and three studies tested oral factor Xa inhibitors (one rivaroxaban, one edoxaban and one apixaban).Analysis showed no difference in the effectiveness of oral DTIs and standard anticoagulation in preventing recurrent pulmonary embolism (OR 1.02, 95% CI 0.50 to 2.04; two studies; 1602 participants; high quality evidence), recurrent venous thromboembolism (OR 0.93, 95% CI 0.52 to 1.66; two studies; 1602 participants; high quality evidence), deep vein thrombosis (DVT) (OR 0.79, 95% CI 0.29 to 2.13; two studies; 1602 participants; high quality evidence) and major bleeding (OR 0.50, 95% CI 0.15 to 1.68; two studies; 1527 participants; high quality evidence).For oral factor Xa inhibitors, when we combined the three included studies together in meta-analyses, there was significant heterogeneity for recurrent pulmonary embolism (OR 1.08, 95% CI 0.46 to 2.56; two studies; 4509 participants; I(2) = 58%; moderate quality evidence). The oral factor Xa inhibitors were no more or less effective in the prevention of recurrent venous thromboembolism (OR 0.85, 95% CI 0.63 to 1.15; three studies; 6295 participants; high quality evidence), DVT (OR 0.72, 95% CI 0.39 to 1.32; two studies; 4509 participants; high quality evidence), all-cause mortality (OR 1.16, 95% CI 0.79 to 1.70; one study; 4817 participants; moderate quality evidence) or major bleeding (OR 0.97, 95% CI 0.59 to 1.62; two studies; 4507 participants; high quality evidence). None of the studies measured quality of life.

AUTHORS' CONCLUSIONS

Moderate to high quality evidence suggests that there are no differences between DOACs and standard anticoagulation for the long-term treatment of pulmonary embolism, for the outcomes recurrent pulmonary embolism, recurrent venous thromboembolism, DVT, all-cause mortality and major bleeding.

Engineering of Harobin for enhanced fibrinolytic activity obtained by random and site-directed mutagenesis

We have previously published a report on the cloning and characterization of Harobin, a fibrinolytic serine protease. However, the broad application of this fibrinolytic enzyme is limited by its low expression level that was achieved in Pichia pastoris. To counteract this shortcoming, random and site-directed mutagenesis have been combined in order to improve functional expression and activity of Harobin. By screening 400 clones from random mutant libraries for enhanced fibrinolytic activity, two mutants were obtained: N111R, R230G. By performing site-directed mutagenesis, a Harobin double mutant, N111R/R230G, was constructed and can be functionally expressed at higher level than the wild type enzyme. In addition, it possessed much higher fibrinolytic and amidolytic activity than the wild type enzyme and other single mutants. The N111R/R230G expressed in basal salts medium was purified by a three step purification procedure. At pH of 6.0-9.0, and the temperature range of 40-90 °C, N111R/R230G was more active and more heat resistant. The fibrinolytic activities of Harobin mutants were completely inhibited by PMSF and SBTI, but not by EDTA, EGTA, DTT, indicating that Harobin is a serine protease. N111R/R230G showed much better anti-thrombosis effect than wild type Harobin and single mutants, and could significantly increase bleeding and clotting time. Intravenous injection of N111R/R230G in spontaneous hypertensive rats (SHR) led to a significant reduction in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) (p < 0.01), while heart rate (HR) was not affected. The in vitro and in vivo results of the present study revealed that Harobin double mutant N111R/R230G is an appropriate candidate for biotechnological applications due to its high expression level and high activity in area of thrombosis and hypertension.