Direct oral anticoagulants versus vitamin K antagonists in antiphospholipid syndrome: A meta-analysis

[Update in the management of chronic thrombo-embolic pulmonary hypertension]

Chronic thrombo-embolic pulmonary hypertension (CTEPH) is a potentially curable form of pulmonary hypertension (PH) that develops in up to 3% of patients after pulmonary embolism (PE). In these patients, PE does not resolve, leading to organized fibrotic clots, with the development of precapillary PH as a result of the proximal obstruction of the pulmonary arteries. In addition, a distal microvasculopathy may also develop, contributing to the increase of pulmonary vascular resistance. Transthoracic echocardiography is the diagnostic tool that allows to establish the suspicion of PH. Ventilation-perfusion lung scintigraphy is the fundamental tool in the study of patients with suspected CTEPH; if it is normal, virtually rules out the diagnosis. Right heart catheterization is mandatory for the diagnosis of these patients. CTEPH is defined as the existence of symptoms, residual perfusion defects and precapillary PH after a minimum period of three months of anticoagulation. Pulmonary angiography helps determine the extent and surgical accessibility of thromboembolic lesions. CTEPH patients are candidates for long-term anticoagulation. Pulmonary endarterectomy is the treatment of choice, resulting in significant clinical and hemodynamic improvement. About 25% of patients have residual PH post-endarterectomy. Balloon pulmonary angioplasty is an endovascular technique that targets more distal lesions, being potentially useful for patients with inoperable CTEPH or persistent/recurrent PH post-endarterectomy. Both types of patients may also benefit from pharmacological treatment for PH. These three therapies are the cornerstone of CTEPH treatment, which has evolved towards a multimodal approach.

Antiphospholipid Syndrome in Patients with Venous Thromboembolism

Unprovoked (or provoked by mild risk factors) venous thromboembolism (VTE) in young patients, VTE in uncommon sites, or cases of unexplained VTE recurrence may be positive for antiphospholipid antibodies (aPL) and thus may be diagnosed with antiphospholipid syndrome (APS). The evaluation of aPL is standardized using immunological tests for anticardiolipin and anti-β2-glycoprotein I. The determination of functional antibodies (lupus anticoagulant) is less standardized, especially in patients on anticoagulant treatment. Patients positive for all the three tests are at high risk of recurrence, which, in turn, might lead to chronic obstruction of pulmonary vessels (chronic thromboembolic pulmonary hypertension). Randomized clinical trials have shown that triple-positive patients should be treated with vitamin K antagonists maintaining an international normalized ratio between 2 and 3. Whether patients with VTE and incomplete aPL profile can be treated with direct oral anticoagulants should be further investigated.

Direct oral anticoagulants vs. vitamin K antagonists in patients with antiphospholipid syndrome: a systematic review and meta-analysis

Optimal treatment regimen for patients with antiphospholipid syndrome (APS) remain unclear. Therefore, the authors sought to compare the outcomes of vitamin K antagonists (VKAs) vs. direct oral anticoagulants (DOACs) in patients with APS.

METHODS

MEDLINE, Embase, and Cochrane Central databases were searched for randomized controlled trials comparing efficacy and safety of VKAs and DOACs inhibitors in patients with APS. Recurrent thrombosis, all-cause mortality, stroke, adverse reactions, and bleeding were among outcomes of interest. Mantel-Haenszel weighted random-effects model was used to calculate relative risks (RRs) with 95% CIs.

RESULTS

The analysis included 625 patients from four randomized controlled trials and one post hoc analysis. Meta-analysis showed statistically non-significant difference between DOACs inhibitors and VKAs in the recurrent thrombosis risk (arterial or venous) [RR 2.77 (95%, CI 0.79, 9.65); P=0.11, I2=50%]. Consistent results were revealed among patients with the previous history of arterial thrombosis [RR 2.76 (95% CI 0.93, 8.16); P=0.75, I2=0%], venous thrombosis [RR 1.71 (95% CI 0.60, 4.84); P=0.31, I2=15%] and patients who were triple antiphospholipid positive [RR 4.12 (95% CI 0.46, 37.10); P=0.21, I2=58%]. DOACs inhibitors were significantly associated with increased risk of stroke [RR 8.51 (95% CI 2.35, 3.82); P=0.47, I2=0%].

CONCLUSION

DOACs exhibited increased risk of stroke among patients with APS. In addition, although not significant, the higher RRs among patients on DOACs may indicate higher risk of thrombotic events associated with DOACs.

Direct-acting oral anticoagulants in antiphospholipid syndrome: A systematic review

The objective of the systematic review is to analyze the efficacy of direct-acting oral anticoagulants (DOAC) in the prophylaxis of thrombosis in antiphospholipid syndrome (APS). We searched for clinical trials, cohort studies and meta-analyses published from January 1, 2012 to September 30, 2022. Articles that analyzed the efficacy of DOAC in the prevention of thrombosis recurrence, with or without comparison with antivitamin K (VKA) drugs, were selected. DOACs, specifically rivaroxaban and apixaban, were significantly less effective than VKAs in preventing recurrence of thrombosis in patients with APS and prior arterial thrombosis or the concomitant presence of two or three different antiphospholipid antibodies. The proportion of patients with severe bleeding as side effect are similar in those treated with DOAC and with VKA. The results argue against the use of DOAC in the treatment of patients with thrombotic APS.

Evolution of Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is an autoimmune prothrombotic disease characterized by thrombosis and/or pregnancy complications caused by antiphospholipid antibodies (aPL). The history of APS can be traced back to observations made during screening programs for syphilis conducted in the mid-20th century, with identification of patients with the so-called biological false-positive serological reactions for syphilis. Initial observation linking aPL with recurrent miscarriages was first reported more than 40 years ago. Since then, our understanding of the pathogenesis and management of APS has evolved markedly. Although APS is an autoimmune disease, anticoagulation mainly with vitamin K antagonists (VKAs) rather than immunomodulation, is the treatment of choice for thrombotic APS. Direct acting oral anticoagulants are inferior to VKAs, especially those with triple-positive APS and arterial thrombosis. Inflammation, complement activation, and thrombosis in the placenta may contribute to pathogenesis of obstetric APS. Heparin, mainly low-molecular-weight heparin, and low-dose aspirin represent the treatments of choice for women with obstetric complications. Increasingly, immunomodulatory agents such as hydroxychloroquine for thrombotic and obstetric APS are being used, especially in patients who are refractory to present standard treatment.

Venous Thromboembolism in the Inflammatory Rheumatic Diseases

Venous thromboembolism (VTE), which includes deep venous thrombosis and pulmonary embolism, is a cardiovascular event whose risk is increased in most inflammatory rheumatic diseases (IRDs). Mechanisms that increase VTE risk include antiphospholipid antibodies (APLs), particularly anticardiolipin antibodies, anti-beta2glycoprotein I antibodies and lupus anticoagulant present together, and inflammation-mediated endothelial injury. Patients with IRDs should receive long-term anticoagulation drugs when the risk of VTE recurrence is high. In the light of recent warnings from regulatory agencies regarding heightened VTE risk with Janus kinase inhibitors, these drugs should be initiated only after a careful assessment of VTE risk in those with IRDs.

The edoxaban‐M4 metabolite and measurement of edoxaban by chromogenic assays in human plasma

Introduction

Edoxaban is the only anti-Xa inhibitor metabolized in pharmacologically active moiety that could interfere with chromogenic anti-Xa assays, especially in case of drug-drug interactions or physiological disorders.

Materials and methods

We evaluated the contribution of the main metabolite of edoxaban, edoxaban-M4 (M4), in 79 plasma samples from patients taking edoxaban. The total anti-Xa activity was evaluated on three different chromogenic factor Xa-based assays. Results were compared with a validated ultra-high-performance liquid chromatography coupled with a tandem mass spectrometry measurement. Edoxaban and its active M4 metabolite have also been spiked separately in normal pooled plasma to assess the sensitivity of chromogenic anti-Xa assays to both molecules individually.

Results

Spiked edoxaban or M4 provided different slopes of linear regression models between chromogenic and chromatographic measurement (from 0.97 for STA Liquid Anti-Xa to 1.10 for Biophen Heparin LRT Low with edoxaban and from 0.70 for Biophen DiXaI High to 0.83 for Biophen Heparin LRT High, respectively). A positive correlation is observed between the increase of the ratio M4/edoxaban with the difference between chromogenic and chromatographic measurements.

Conclusion

Edoxaban and M4 do not similarly impact chromogenic assays, leading to biased chromogenic estimations of ponderal concentrations. In patient samples, this impact is even more important at low concentrations or in the case of an increase in the M4/edoxaban ratio because of hepatic or renal impairments or in case of drug interactions. This study highlights the limitations and risks of error of expressing results in ponderal concentrations instead of global activity anti-Xa.

Antithrombotics and new interventions for venous thromboembolism: Exploring possibilities beyond factor IIa and factor Xa inhibition

Direct oral anti-activated factor X and antithrombin agents have largely replaced vitamin K antagonists as the standard of care in treatment of venous thromboembolism. However, gaps in efficacy and safety persist, notably in end-stage renal disease, implantable heart valves or assist devices, extracorporeal support of the circulation, and antiphospholipid syndrome. Inhibition of coagulation factor XI (FXI) emerges as a promising new therapeutic target. Antisense oligonucleotides offer potential advantages as a prophylactic or therapeutic modality, with one dose-finding trial in orthopedic surgery already published. In addition, monoclonal antibodies blocking activation and/or activity of activated factor XI are investigated, as are small-molecule inhibitors with rapid offset of action. Further potential targets include upstream components of the contact pathway such as factor XII, polyphosphates, or kallikrein. Finally, catheter-directed, pharmacomechanical antithrombotic strategies have been developed for high- and intermediate-risk pulmonary embolism, and large randomized trials aiming to validate their efficacy, safety, and prognostic impact are about to start.

Interventional and pharmacological management of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is caused by obstruction of the pulmonary vasculature, leading to increased pulmonary vascular resistance and ultimately right ventricular failure, the leading cause of death in non-operated patients. This article reviews the current management of CTEPH. The standard of care in CTEPH is pulmonary endarterectomy (PEA). However, up to 40% of patients with CTEPH are ineligible for PEA, and up to 51% develop persistent/recurrent PH after PEA. Riociguat is currently the only medical therapy licensed for treatment of inoperable or persistent/recurrent CTEPH after PEA based on the results of the Phase III CHEST-1 study. Studies of balloon pulmonary angioplasty (BPA) have shown benefits in patients with inoperable or persistent/recurrent CTEPH after PEA; however, data are lacking from large, prospective, controlled studies. Studies of macitentan in patients with inoperable CTEPH and treprostinil in patients with inoperable or persistent/recurrent CTEPH showed positive results. Combination therapy is under evaluation in CTEPH, and long-term data are not available. In the future, CTEPH may be managed by PEA, medical therapy or BPA - alone or in combination, according to individual patient needs. Patients should be referred to experienced centers capable of assessing and delivering all options.