New Anticoagulants

Anticoagulant use in older persons at risk for falls: therapeutic dilemmas-a clinical review

PURPOSE

The aim of this clinical narrative review was to summarise the existing knowledge on the use of anticoagulants and potential adverse events in older people at risk of falls with a history of atrial fibrillation or venous thromboembolism. The review also offers practical steps prescribers can take when (de-)prescribing anticoagulants to maximise safety.

METHODS

Literature searches were conducted using PubMed, Embase and Scopus. Additional articles were identified by searching reference lists.

RESULTS

Anticoagulants are often underused in older people due to concerns about the risk of falls and intracranial haemorrhage. However, evidence suggests that the absolute risk is low and outweighed by the reduction in stroke risk. DOACs are now recommended first line for most patients due to their favourable safety profile. Off-label dose reduction of DOACs is not recommended due to reduced efficacy with limited reduction in bleeding risk. Medication review and falls prevention strategies should be implemented before prescribing anticoagulation. Deprescribing should be considered in severe frailty, limited life expectancy and increased bleeding risk (e.g., cerebral microbleeds).

CONCLUSION

When considering whether to (de-)prescribe anticoagulants, it is important to consider the risks associated with stopping therapy in addition to potential adverse events. Shared decision-making with the patient and their carers is crucial as patient and prescriber views often differ.

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.

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.

Marine Biological Macromolecules and Chemically Modified Macromolecules; Potential Anticoagulants

Coagulation is a potential defense mechanism that involves activating a series of zymogens to convert soluble fibrinogen to insoluble fibrin clots to prevent bleeding and hemorrhagic complications. To prevent the extra formation and diffusion of clots, the counterbalance inhibitory mechanism is activated at levels of the coagulation pathway. Contrariwise, this system can evade normal control due to either inherited or acquired defects or aging which leads to unusual clots formation. The abnormal formations and deposition of excess fibrin trigger serious arterial and cardiovascular diseases. Although heparin and heparin-based anticoagulants are a widely prescribed class of anticoagulants, the clinical use of heparin has limitations due to the unpredictable anticoagulation, risk of bleeding, and other complications. Hence, significant interest has been established over the years to investigate alternative therapeutic anticoagulants from natural sources, especially from marine sources with good safety and potency due to their unique chemical structure and biological activity. This review summarizes the coagulation cascade and potential macromolecular anticoagulants derived from marine flora and fauna.

Comparison of Aspirin and Rivaroxaban Plus Aspirin in the Management of Stable Coronary Artery Disease or Peripheral Artery Disease: A Systematic Review of Randomized Controlled Trials

Introduction

Low-dose aspirin or clopidogrel, statins, renin–angiotensin system inhibitors, and beta blockers are the cornerstone therapy for cardiovascular prevention in patients with coronary heart disease. Using only single-antiplatelet therapy for secondary prevention in patients with stable coronary artery disease (SCAD) and/or peripheral artery disease (PAD) has a significant risk of recurrent thrombotic complications.

Objective

This systematic review aimed to compare aspirin alone and its combination with rivaroxaban for secondary cardiovascular prevention in patients with SCAD and/or PAD.

Methods

The literature search was conducted on PubMed, ClinicalTrials.gov, Cochrane Library, and Google Scholar for articles published from November 2011 to September 2021. An advanced search strategy was used to retrieve relevant studies related to aspirin and/or rivaroxaban use for secondary cardiovascular prevention in patients with SCAD and/or PAD. Records identified from the databases were extracted using a data-abstraction format prepared in Microsoft Excel. Studies’ methodological quality was assessed using the Cochrane risk-of-bias tool for randomized trials. This systematic review is registered in PROSPERO (CRD42022306598) and was prepared based on the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines.

Results

A total of five randomized controlled trials (RCTs) with 33,959 participants were included for final analysis. These studies showed that rivaroxaban with aspirin was more effective than the standard therapy of aspirin alone in the prevention of secondary cardiovascular events (major adverse cardiovascular events (MACEs) and/or major adverse limb events (MALEs), but the combination increased major bleeding.

Conclusion

The combination of rivaroxaban with aspirin is more effective than aspirin alone in the prevention of both MACEs and MALEs in patients with stable CAD and/or PAD. However, the combination treatment is associated with increased of major bleeding. Therefore, the combination of rivaroxaban and aspirin is superior to monotherapy in the management of patients with a high risk of developing MACEs and MALEs.

Expert Recommendations on the Usage of Non-vitamin K Antagonist Oral Anticoagulants (NOACs) from India: Current Perspective and Future Direction

Non-vitamin K antagonist oral anticoagulants (NOACs) are a new class of anticoagulant drugs used in the prevention and treatment of venous thromboembolism (VTE) and atrial fibrillation (AF). Anticoagulation requires the integration of the correct type and dose of oral anticoagulants based on patient characteristic, and therefore therapy needs to be individualized for each patient. Growing scientific evidence from studies on NOACs has led to a better understanding of their benefits and safety. A large amount of available data creates a necessity for an adaptable practical document for the usage of NOACs in India. The current consensus, developed by experts from India, aims to give recommendations on various frequently raised clinical questions with regards to NOACs and its usage. This practical document provides a platform upon which future guidelines, policies, training, and education for the use of NOACs can be tailored.

Pharmacokinetics and Pharmacodynamics of a Depolymerized Glycosaminoglycan from Holothuria fuscopunctata, a Novel Anticoagulant Candidate, in Rats by Bioanalytical Methods

dHG-5 (Mw 5.3 kD) is a depolymerized glycosaminoglycan from sea cucumber Holothuria fuscopunctata. As a selective inhibitor of intrinsic Xase (iXase), preclinical study showed it was a promising anticoagulant candidate without obvious bleeding risk. In this work, two bioanalytical methods based on the anti-iXase and activated partial thromboplastin time (APTT) prolongation activities were established and validated to determine dHG-5 concentrations in plasma and urine samples. After single subcutaneous administration of dHG-5 at 5, 9, and 16.2 mg/kg to rats, the time to peak concentration (Tmax) was at about 1 h, and the peak concentration (Cmax) was 2.70, 6.50, and 10.11 μg/mL, respectively. The plasma elimination half-life(T1/2β) was also about 1 h and dHG-5 could be almost completely absorbed after s.c. administration. Additionally, the pharmacodynamics of dHG-5 was positively correlated with its pharmacokinetics, as determined by rat plasma APTT and anti-iXase method, respectively. dHG-5 was mainly excreted by urine as the unchanged parent drug and about 60% was excreted within 48 h. The results suggested that dHG-5 could be almost completely absorbed after subcutaneous injection and the pharmacokinetics of dHG-5 are predictable. Studying pharmacokinetics of dHG-5 could provide valuable information for future clinical studies.

Cyclic peptide FXII inhibitor provides safe anticoagulation in a thrombosis model and in artificial lungs

Inhibiting thrombosis without generating bleeding risks is a major challenge in medicine. A promising solution may be the inhibition of coagulation factor XII (FXII), because its knock-out or inhibition in animals reduced thrombosis without causing abnormal bleeding. Herein, we have engineered a macrocyclic peptide inhibitor of activated FXII (FXIIa) with sub-nanomolar activity (K_i = 370 ± 40 pM) and a high stability (t_1/2 > 5 days in plasma), allowing for the preclinical evaluation of a first synthetic FXIIa inhibitor. This 1899 Da molecule, termed FXII900, efficiently blocks FXIIa in mice, rabbits, and pigs. We found that it reduces ferric-chloride-induced experimental thrombosis in mice and suppresses blood coagulation in an extracorporeal membrane oxygenation (ECMO) setting in rabbits, all without increasing the bleeding risk. This shows that FXIIa activity is controllable in vivo with a synthetic inhibitor, and that the inhibitor FXII900 is a promising candidate for safe thromboprotection in acute medical conditions.

[SBA 2020: Regional anesthesia guideline for using anticoagulants update]

The development of protocols to prevent perioperative Venous Thromboembolism (VTE) and the introduction of increasingly potent antithrombotic drugs have resulted in concerns of increased risk of neuraxial bleeding. Since the Brazilian Society of Anesthesiology (SBA) 2014 guideline, new oral anticoagulant drugs were approved by international regulating agencies, and by ANVISA. Societies and organizations that try to approach concerns through guidelines have presented conflicting perioperative management recommendations. As a response to these issues and to the need for a more rational approach, managements were updated in the present narrative revision, and guideline statements made. They were projected to encourage safe and quality patient care, but cannot assure specific results. Like any clinical guide recommendation, they are subject to review as knowledge grows, on specific complications, for example. The objective was to assess safety aspects of regional analgesia and anesthesia in patients using antithrombotic drugs, such as: possible technique-associated complications; spinal hematoma-associated risk factors, prevention strategies, diagnosis and treatment; safe interval for discontinuing and reinitiating medication after regional blockade.

Specificities of Approaches to Anticoagulant Therapy in Comorbid Patients with Atrial Fibrillation, Diabetes Mellitus and Impaired Kidney Function

Comorbid patients with atrial fibrillation, diabetes mellitus and chronic kidney disease are at high risk of stroke. The direct oral anticoagulants are indicated for them. The choice of a drug should be based on the results of randomized clinical trials, in which the patients profile corresponds to that in the real Russian clinical practice as much as possible. Taking into account the peculiarities of comorbidity in this category of patients, the requirements for their protection should be considered comprehensively. Along with the prevention of thromboembolic complications, it is necessary that the selected direct oral anticoagulant provides a reduction in the risk of cardiovascular complications, which are typical of diabetes mellitus, and slows down the progression of renal filtration function decline. Rivaroxaban may meet these requirements; its use has significant advantage in high adherence to therapy.

Periprocedural Direct Oral Anticoagulant Management: The RA-ACOD Prospective, Multicenter Real-World Registry

Introduction  There is scarce real-world experience regarding direct oral anticoagulants (DOACs) perioperative management. No study before has linked bridging therapy or DOAC-free time (pre-plus postoperative time without DOAC) with outcome. The aim of this study was to investigate real-world management and outcomes. Methods  RA-ACOD is a prospective, observational, multicenter registry of adult patients on DOAC treatment requiring surgery. Primary outcomes were thrombotic and hemorrhagic complications. Follow-up was immediate postoperative (24-48 hours) and 30 days. Statistics were performed using a univariate and multivariate analysis. Data are presented as odds ratios (ORs [95% confidence interval]). Results  From 26 Spanish hospitals, 901 patients were analyzed (53.5% major surgeries): 322 on apixaban, 304 on rivaroxaban, 267 on dabigatran, 8 on edoxaban. Fourteen (1.6%) patients suffered a thrombotic event, related to preoperative DOAC withdrawal (OR: 1.57 [1.03-2.4]) and DOAC-free time longer than 6 days (OR: 5.42 [1.18-26]). Minor bleeding events were described in 76 (8.4%) patients, with higher incidence for dabigatran (12.7%) versus other DOACs (6.6%). Major bleeding events occurred in 17 (1.9%) patients. Bridging therapy was used in 315 (35%) patients. It was associated with minor (OR: 2.57 [1.3-5.07]) and major (OR: 4.2 [1.4-12.3]) bleeding events, without decreasing thrombotic events. Conclusion  This study offers real-world data on perioperative DOAC management and outcomes in a large prospective sample size to date with a high percentage of major surgery. Short-term preprocedural DOAC interruption depending on the drug, hemorrhagic risk, and renal function, without bridging therapy and a reduced DOAC-free time, seems the safest practice.

Wild P, H. Prochaska J. Specialized Management of Oral Anticoagulation Therapy Improves Outcome in Patients with Chronic Renal Insufficiency

Oral anticoagulation (OAC) is effective at preventing and treating thromboses and thromboembolism in patients with normal renal function. We aimed to research the impact of severe renal failure (RF) on patient outcome and to determine the potential benefit of caring for these patients in a specialized coagulation service (CS). A total of 1516 usual medical care patients and 756 CS-managed patients of the thrombEVAL multicenter (21 centers), prospective, cohort study (NCT01809015) were analyzed in a 3-year follow-up. Patients with RF (serum creatinine >3 mg/dL, no renal replacement therapy) were compared to patients without RF in usual care and a CS. The fluctuations in the international normalized ratios were significantly lower in CS-managed patients, and regardless of treatment in usual care or a CS, the time in therapeutic range was significantly lower in RF patients. Cox regression-adjusted hazard ratios for long-term outcome (1.5, 95% CI: 1.22–1.83, p < 0.001), death (1.62, CI: 1.27–2.08, p < 0.001), and hospitalization (1.21, CI: 1.02–1.44, p = 0.032) were significantly higher in RF patients in usual care. Furthermore, there was a trend of more bleeding events in RF patients. CS-treated patients had significantly lower adjusted hazard ratios for death (0.24, CI: 0.14–0.39, p < 0.001), hospitalizations (0.41, CI: 0.34–0.5, p < 0.001), clinically relevant bleeding (0.29, CI: 0.18–0.47, p < 0.001), and major bleeding (0.33, CI: 0.18–0.59, p < 0.001). Thus, patients who required oral anticoagulation therapy benefitted significantly from being managed in a specialized coagulation service, regardless of their renal function.

Phosphorylcholine- and cation-bearing copolymer coating with superior antibiofilm and antithrombotic properties for blood-contacting devices

The phosphorylcholine- and cation-bering copolymer coating endowed the blood-contacting devices with superior antibiofilm and antithrombotic ability.

Critical Issues and Recent Advances in Anticoagulant Therapy: A Review

As the population is aging, clinicians are coming across more patients with atrial fibrillation and venous thromboembolism requiring anticoagulation to prevent stroke and systemic embolisms. Due to a high prevalence and unfavorable consequences, managing thromboembolic diseases have become areas of clinical concern. Traditional anticoagulants like heparin, low molecular weight heparin and warfarin have been used for the prevention and treatment of venous and arterial thromboses. But, issues of bleeding, parenteral route of administration, or the need for frequent monitoring due to variability in response respectively limit their use. The article gives an overview of coagulation along with existing therapy available for anticoagulation and to present an update on utility and recent advances of new oral anticoagulants (NOACs) beginning from their nomenclature, advantages, disadvantages, precautions and contraindications compared with those of vitamin K antagonists (VKAs) based on a large number of recent studies and clinical trials.

Identification and inhibitory activity against α-thrombin of a novel anticoagulant peptide derived from oyster (Crassostrea gigas) protein

A newly discovered anticoagulant peptide was isolated, purified and identified from the pepsin hydrolysate of oyster (Crassostrea gigas) which could potently prolong the activated partial thromboplastin time and the thrombin time. The anticoagulant peptide with a 1264.36 Da molecular mass was similar to the amino acid sequence of the C-terminal segment (DFEEIPEEYLQ) of hirudin (a potent thrombin inhibitor). The peptide specifically inhibited a vital blood coagulation factor: thrombin. The molecular docking energy scores of the anticoagulant peptide with the active site, exosite-I and exosite-II of thrombin were 132.355 kcal mol-1, 151.266 kcal mol-1 and 147.317 kcal mol-1, respectively. The anticoagulant peptide interacted with thrombin by competing with fibrinogen for an anion-binding exosite I. In the anticoagulant peptide-thrombin complex, there are seven hydrogen bonds and reciprocity exists between hydrogen atoms and oxygen atoms, and electrostatic and hydrophobic interactions are also involved. Such abundant interactions may be accountable for the high affinity and specificity of the anticoagulant peptide.

Food-derived antithrombotic peptides: Preparation, identification, and interactions with thrombin

Thromboembolism and its sequelae have been the leading causes of morbidity and mortality throughout the world. Food-derived antithrombotic peptides, as potential ingredients in health-promoting functional foods targeting thrombus, have attracted increasing attention because of their high biological activities, low toxicity, and ease of metabolism in the human body. This review presents the conventional workflow of preparation, isolation and identification of antithrombotic peptides from various kinds of food materials. More importantly, to analyze the antithrombotic effects and mechanism of antithrombotic peptides, methods for interaction of anticoagulant peptides and thrombin, the main participant in thrombosis, were analyzed from biochemistry, solution chemistry and crystal chemistry. The present study is intended to highlight the recent advances in research of food-derived antithrombotic peptide as a novel vehicle in the field of food science and nutrition. Future outlooks are highlighted with the aim to suggest a research line to be followed in further studies with the introduced research approach.

A Review on the New and Old Anticoagulants

Anticoagulants serve as the primary strategy for the prevention and treatment of both arterial and venous thromboembolism. Anticoagulants disrupt coagulation by interfering at various points in the coagulation cascade. This class of medications does not lyse clots that already exist; rather, it prevents thrombus formation and prevents or slows the extension of an existing clot. For decades, the standard therapy for patients requiring oral anticoagulation was warfarin. However, due to some of the shortcomings of warfarin, including the need for continuous routine monitoring, longtime onset and offset of anticoagulation effect, major food and drug interactions, and high incidence of bleeding, newer agents, termed direct oral anticoagulants, or DOACs were developed. This article will provide a review of clinically important information regarding the most commonly used anticoagulants and their reversal agents.

Semisynthesis of ent-norstrobane diterpenoids as potential inhibitor for factor Xa

A semisynthesis of two ent-strobane diterpenoids strobols C (7) and D (14) was accomplished via a Wagnar-Meerwein rearrangement. Compounds 7, 14, and the intermediate products were evaluated for their inhibition on factor Xa (FXa). Among all the compounds screened for FXa inhibitory activity, three compounds 6, 7, and 9 showed significant inhibitory activities with IC₅₀ values of 1067 ± 164, 81 ± 11, 1023 ± 89 nM, respectively. The inhibitory activity on FXa described in this study highlight the importance of structural modification based on natural products in the development of FXa inhibitors.

Outcomes of intraparenchymal hemorrhage after direct oral anticoagulant or vitamin K antagonist therapy: A systematic review and meta-analysis

Direct Oral Anticoagulants (DOAC) are increasingly used as an alternative to vitamin-K antagonists (VKA) for anticoagulation and have shown lower rates of intracranial hemorrhage; however, there is disagreement in the literature over the outcomes of the intraparenchymal hemorrhages (IPH) associated with DOACs, and clinical concern regarding the lack of standardized reversal strategies for DOACs. Thus, the aim of this meta-analysis was to compare mortality, hematoma volume, and risk of hematoma expansion in patients who developed an IPH on DOACs versus VKA. A systematic review of the literature was conducted in accordance with the PRISMA guidelines. Studies were selected that reported on mortality, hematoma expansion, and hematoma volume in DOAC-associated IPH. Pooled risk ratios (RR) were calculated for mortality and hematoma expansion and pooled mean difference (MD) was calculated for hematoma volume (ml) using random-effect models. 15 studies reporting on 1238 patients were included in the systematic review. Eleven of these compared DOAC-IPH to VKA-IPH and were pooled quantitatively. DOAC-IPH was not associated with increased mortality risk (RR: 0.95, 95%-CI: 0.72 -1.27) or increased hematoma expansion risk (RR: 0.92; 95%-CI: 0.75-1.12) compared to VKA-IPH. The hematoma volume of DOAC- IPH was statistically significantly smaller than VKA-IPH (MD: -12.14 ml; 95%-CI: -15.38; -8.89). In conclusion, DOAC-IPH was not associated with increased mortality or hematoma expansion compared to VKA-IPH and may be associated with a smaller hematoma volume.

Endothelial dysfunction and platelet hyperactivity in type 2 diabetes mellitus: molecular insights and therapeutic strategies

The incidence and prevalence of diabetes mellitus is rapidly increasing worldwide at an alarming rate. Type 2 diabetes mellitus (T2DM) is the most prevalent form of diabetes, accounting for approximately 90-95% of the total diabetes cases worldwide. Besides affecting the ability of body to use glucose, it is associated with micro-vascular and macro-vascular complications. Augmented atherosclerosis is documented to be the key factor leading to vascular complications in T2DM patients. The metabolic milieu of T2DM, including insulin resistance, hyperglycemia and release of excess free fatty acids, along with other metabolic abnormalities affects vascular wall by a series of events including endothelial dysfunction, platelet hyperactivity, oxidative stress and low-grade inflammation. Activation of these events further enhances vasoconstriction and promotes thrombus formation, ultimately resulting in the development of atherosclerosis. All these evidences are supported by the clinical trials reporting the importance of endothelial dysfunction and platelet hyperactivity in the pathogenesis of atherosclerotic vascular complications. In this review, an attempt has been made to comprehensively compile updated information available in context of endothelial and platelet dysfunction in T2DM.

New antiplatelet drugs and new oral anticoagulants

In our daily anaesthetic practice, we are confronted with an increasing number of patients treated with either antiplatelet or anticoagulant agents. During the last decade, changes have occurred that make the handling of antithrombotic medication a challenging part of anaesthetic perioperative management. In this review, the authors discuss the most important antiplatelet and anticoagulant drugs, the perioperative management, the handling of bleeding complications, and the interpretation of some laboratory analyses related to these agents.

Factor Xa inhibitors versus vitamin K antagonists for preventing cerebral or systemic embolism in patients with atrial fibrillation

BACKGROUND

Factor Xa inhibitors and vitamin K antagonists (VKAs) are now recommended in treatment guidelines for preventing stroke and systemic embolic events in people with atrial fibrillation (AF). This is an update of a Cochrane review previously published in 2013.

OBJECTIVES

To assess the effectiveness and safety of treatment with factor Xa inhibitors versus VKAs for preventing cerebral or systemic embolic events in people with AF.

SEARCH METHODS

We searched the trials registers of the Cochrane Stroke Group and the Cochrane Heart Group (September 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (August 2017), MEDLINE (1950 to April 2017), and Embase (1980 to April 2017). We also contacted pharmaceutical companies, authors and sponsors of relevant published trials. We used outcome data from marketing authorisation applications of apixaban, edoxaban and rivaroxaban that were submitted to regulatory authorities in Europe and the USA.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that directly compared the effects of long-term treatment (lasting more than four weeks) with factor Xa inhibitors versus VKAs for preventing cerebral and systemic embolism in people with AF.

DATA COLLECTION AND ANALYSIS

The primary efficacy outcome was the composite endpoint of all strokes and systemic embolic events. Two review authors independently extracted data, and assessed the quality of the trials and the risk of bias. We calculated a weighted estimate of the typical treatment effect across trials using the odds ratio (OR) with 95% confidence interval (CI) by means of a fixed-effect model. In case of moderate or high heterogeneity of treatment effects, we used a random-effects model to compare the overall treatment effects. We also performed a pre-specified sensitivity analysis excluding any open-label studies.

MAIN RESULTS

We included data from 67,688 participants randomised into 13 RCTs. The included trials directly compared dose-adjusted warfarin with either apixaban, betrixaban, darexaban, edoxaban, idraparinux, idrabiotaparinux, or rivaroxaban. The majority of the included data (approximately 90%) was from apixaban, edoxaban, and rivaroxaban.The composite primary efficacy endpoint of all strokes (both ischaemic and haemorrhagic) and non-central nervous systemic embolic events was reported in all of the included studies. Treatment with a factor Xa inhibitor significantly decreased the number of strokes and systemic embolic events compared with dose-adjusted warfarin in participants with AF (OR 0.89, 95% CI 0.82 to 0.97; 13 studies; 67,477 participants; high-quality evidence).Treatment with a factor Xa inhibitor significantly reduced the number of major bleedings compared with warfarin (OR 0.78, 95% CI 0.73 to 0.84; 13 studies; 67,396 participants; moderate-quality evidence). There was, however, statistically significant and high heterogeneity (I2 = 83%). When we repeated this analysis using a random-effects model, it did not show a statistically significant decrease in the number of major bleedings (OR 0.88, 95% CI 0.66 to 1.17). A pre-specified sensitivity analysis excluding all open-label studies showed that treatment with a factor Xa inhibitor significantly reduced the number of major bleedings compared with warfarin (OR 0.75, 95% CI 0.69 to 0.81), but high heterogeneity was also observed in this analysis (I2 = 72%). The same sensitivity analysis using a random-effects model also showed a statistically significant decrease in the number of major bleedings in participants treated with factor Xa inhibitors (OR 0.76, 95% CI 0.60 to 0.96).Treatment with a factor Xa inhibitor significantly reduced the risk of intracranial haemorrhages (ICHs) compared with warfarin (OR 0.50, 95% CI 0.42 to 0.59; 12 studies; 66,259 participants; high-quality evidence). We observed moderate, but statistically significant heterogeneity (I2 = 55%). The pre-specified sensitivity analysis excluding open-label studies showed that treatment with a factor Xa inhibitor significantly reduced the number of ICHs compared with warfarin (OR 0.47, 95% CI 0.40 to 0.56), with low, non-statistically significant heterogeneity (I2 = 27%).Treatment with a factor Xa inhibitor also significantly reduced the number of all-cause deaths compared with warfarin (OR 0.89, 95% 0.83 to 0.95; 10 studies; 65,624 participants; moderate-quality evidence).

AUTHORS' CONCLUSIONS

Treatment with factor Xa inhibitors significantly reduced the number of strokes and systemic embolic events compared with warfarin in people with AF. The absolute effect of factor Xa inhibitors compared with warfarin treatment was, however, rather small. Factor Xa inhibitors also reduced the number of ICHs, all-cause deaths and major bleedings compared with warfarin, although the evidence for a reduction in the latter is less robust.

Four-factor prothrombin complex concentrate improves thrombin generation and prothrombin time in patients with bleeding complications related to rivaroxaban: a single-center pilot trial

Background

Direct oral anticoagulants (DOACs) pose a great challenge for physicians in life-threatening bleeding events. The aim of this study was to test the efficacy of reversing the DOAC rivaroxaban using four-factor PCC (prothrombin complex concentrate), a non-specific reversing agent.

Methods

Patients with life-threatening bleeding events during rivaroxaban treatment were included and administered 25 U kg⁻¹ of PCC. Blood samples were collected immediately prior to as well as after PCC treatment at predefined time intervals. The primary endpoint was defined as the difference in thrombin generation (TG) parameters ETP (endogenous thrombin potential) and C_max (peak thrombin generation) prior to and ten minutes subsequent to PCC treatment.

Results

Thirteen patients, of whom the majority suffered from intra-cranial haemorrhage (ICH) or subdural haemorrhage (SDH), were included and administered PCC. The results show that the ETP (TG) significantly (p = 0.001) improved by 68% and C_max (TG) by 54% (p = 0.001) during PCC treatment. In addition, the Quick value (prothrombin time: Quick^PT) significantly improved by 28% and the activated partial thromboplastin time (aPTT) was decreased by 7% ten minutes after PCC administration. C_max was reduced at baseline, but not ETP, aPTT or Quick^PT. Lag time until initiation (TG, t_lag), thromboelastometry clotting time (CT_EXTEM) and time to peak (TG, t_max) correlated best with measured rivaroxaban levels and were out of normal ranges at baseline, but did not improve after PCC administration. In 77% of the patients bleeding (ICH/SDH-progression) ceased following PCC administration. During the study three participants passed away due to other complications not related to PCC treatment. The possibility of thrombosis formation was also evaluated seven days after administering PCC and no thromboses were found.

Conclusions

This study shows that use of PCC improved ETP, C_max, Quick^PT and aPTT. However, of these parameters, only C_max was reduced at the defined baseline. It can be concluded that CT_EXTEM, t_lag and t_max correlated best with the measured rivaroxaban levels. The study drug was found to be safe. Nonetheless, additional studies specifically targeting assessment of clinical endpoints should be performed to further confirm these findings.

Clinical trial registration

EudraCT trial No. 2013–004484-31.

Electronic supplementary material

The online version of this article (10.1186/s12959-017-0158-9) contains supplementary material, which is available to authorized users.

The perioperative management of new direct oral anticoagulants: a question without answers

New direct oral anticoagulant agents (DOAC) are currently licensed for thromboprophylaxis after hip and knee arthroplasty and for longterm prevention of thromboembolic events in non-valvular atrial fibrillation as well as treatment and secondary prophylaxis of venous thromboembolism. Some other medical indications are emerging. Thus, anaesthesiologists are increasingly likely to encounter patients on these drugs who need elective or emergency surgery. Due to the lack of experience and data, the management of DOAC in the perioperative period is controversial. In this article, we review available information and recommendations regarding the periprocedural management of the currently most clinically developed DOAC, apixaban, dabigatran, and rivaroxaban. We discuss two trends of managing patients on DOAC for elective surgery. The first is stopping the DOAC 1–5 days before surgery (depending on the drug, patient and bleeding risk) without bridging. The second is stopping the DOAC 5 days preoperatively and bridging with low-molecular-weight heparin. The management of patients on DOAC needing emergency surgery is also reviewed. As no data exist for the use of haemostatic products for the reversal of the anticoagulant effect in these cases, rescue treatment recommendations are proposed.

In vivo activation and functions of the protease factor XII

Combinations of proinflammatory and procoagulant reactions are the unifying principle for a variety of disorders affecting the cardiovascular system. Factor XII (FXII, Hageman factor) is a plasma protease that initiates the contact system. The biochemistry of the contact system in vitro is well understood; however, its in vivo functions are just beginning to emerge. The current review concentrates on activators and functions of the FXII-driven contact system in vivo. Elucidating its physiologic activities offers the exciting opportunity to develop strategies for the safe interference with both thrombotic and inflammatory diseases.

FVIIa-sTF and Thrombin Inhibitory Activities of Compounds Isolated from Microcystis aeruginosa K-139

The rise of bleeding and bleeding complications caused by oral anticoagulant use are serious problems nowadays. Strategies that block the initiation step in blood coagulation involving activated factor VII-tissue factor (fVIIa-TF) have been considered. This study explores toxic Microcystis aeruginosa K-139, from Lake Kasumigaura, Ibaraki, Japan, as a promising cyanobacterium for isolation of fVIIa-sTF inhibitors. M. aeruginosa K-139 underwent reversed-phase solid-phase extraction (ODS-SPE) from 20% MeOH to MeOH elution with 40%-MeOH increments, which afforded aeruginosin K-139 in the 60% MeOH fraction; micropeptin K-139 and microviridin B in the MeOH fraction. Aeruginosin K-139 displayed an fVIIa-sTF inhibitory activity of ~166 µM, within a 95% confidence interval. Micropeptin K-139 inhibited fVIIa-sTF with EC₅₀ 10.62 µM, which was more efficient than thrombin inhibition of EC₅₀ 26.94 µM. The thrombin/fVIIa-sTF ratio of 2.54 in micropeptin K-139 is higher than those in 4-amidinophenylmethane sulfonyl fluoride (APMSF) and leupeptin, when used as positive controls. This study proves that M. aeruginosa K-139 is a new source of fVIIa-sTF inhibitors. It also opens a new avenue for micropeptin K-139 and related depsipeptides as fVIIa-sTF inhibitors.

Trends in the prescription of novel oral anticoagulants in UK primary care

AIMS

Novel oral anticoagulants (NOACs) are alternatives to vitamin-K antagonists (VKAs) for the prevention of thromboembolism. It is unclear how NOACs have been adopted in the UK since first introduced in 2008. The present study was conducted to describe the trends in the prescription of NOACs in the UK, including dabigatran, rivaroxaban and apixaban.

METHODS

Using the UK's Clinical Practice Research Datalink, the rates of new use of NOACs and VKAs from 2009 to 2015 were calculated using Poisson regression. Patient characteristics associated with NOAC initiation were identified using multivariate logistic regression.

RESULTS

The overall rate of oral anticoagulant initiation increased by 58% over the study period [rate ratio (RR) 1.58; 95% confidence interval (CI) 1.23, 2.03], even as the rate of new VKA use decreased by 31% (RR 0.69; 95% CI 0.52, 0.93). By contrast, the rate of initiation of NOAC increased, particularly from 2012 onwards, with a 17-fold increase from 2012 to 2015 (RR 17.68; 95% CI 12.16, 25.71). In 2015, NOACs accounted for 56.5% of oral anticoagulant prescriptions, with rivaroxaban prescribed most frequently, followed by apixaban and then dabigatran. Compared to VKAs, new NOAC users were less likely to have congestive heart failure, coronary artery disease and peripheral vascular disease, and more likely to have a history of ischaemic stroke.

CONCLUSIONS

In the UK, the rate of initiation of NOACs has increased substantially since 2009, and these agents have now surpassed VKAs as the anticoagulant of choice. Moreover, the characteristics of patients initiated on NOACs have changed over time, and this should be accounted for in future studies comparing NOACs and VKAs.

Vitamin K antagonists: relative strengths and weaknesses vs. direct oral anticoagulants for stroke prevention in patients with atrial fibrillation

Vitamin K antagonists (VKAs) have been the mainstay of anticoagulation therapy for more than 50 years. VKAs are mainly used for the prevention of stroke in patients with atrial fibrillation (AF) and the treatment and secondary prevention of venous thromboembolism. In the past 5 years, four new agents-the direct factor Xa inhibitors apixaban, edoxaban and rivaroxaban and the direct thrombin inhibitor dabigatran [collectively known as direct oral anticoagulants (DOACs) or non-VKA oral anticoagulants]-have been approved for these and other indications. Despite these new treatment options, the VKA warfarin currently remains the most frequently prescribed oral anticoagulant. The availability of DOACs provides an alternative management option for patients with AF, especially when the treating physician is hesitant to prescribe a VKA owing to associated limitations, such as food and drug interactions, and concerns about bleeding complications. Currently available real-world evidence shows that DOACs have similar or improved effectiveness and safety outcomes compared with warfarin. Treatment decisions on which DOAC is best suited for which patient to maximize safety and effectiveness should take into account not only clinically relevant patient characteristics but also patient preference. This article reviews and highlights real and perceived implications of VKAs for the prevention of stroke in patients with non-valvular AF, with specific reference to their strengths and weaknesses compared with DOACs.

Cardiac tachyarrhythmias and anaesthesia: General principles and focus on atrial fibrillation

Cardiac tachyarrhythmias are encountered commonly during the perioperative period and need to be promptly identified and appropriately managed by the anaesthesiologist. This review intends to highlight important aspects of these tachyarrhythmias and explore a temporal relationship between common medications employed in the perioperative period and their causation. Mechanisms of initiation of tachyarrhythmias, drugs that can trigger those, as well as their diagnosis and management, are also parts of the current review. Cardiac tachyarrhythmias may not always require treatment, and sometimes, aggressive management can trigger more serious types of arrhythmias. A thorough understanding of these tachyarrhythmias and their pathogenesis enables adopting a more objective approach, eschewing risks of inappropriate or unnecessary management strategies. We performed a MEDLINE search using combinations of MeSH terms such as ‘cardiac’, ‘arrhythmias’, ‘anaesthesia’, ‘perioperative’, ‘tachyarrhythmias’ and ‘anaesthetic implications’. We reviewed the relevant publications with regard to cardiac tachyarrhythmias occurring in the perioperative period.

Ex vivo reversal of effects of rivaroxaban evaluated using thromboelastometry and thrombin generation assay

Background

In major bleeding events, the new direct oral anticoagulants pose a great challenge for physicians. The aim of the study was to test for ex vivo reversal of the direct oral anticoagulant rivaroxaban with various non-specific reversal agents: prothrombin complex concentrate (PCC), activated prothrombin complex concentrate (aPCC), recombinant activated factor VII (rFVIIa), and fibrinogen concentrate (FI).

Methods

Blood was obtained from healthy volunteers and from patients treated with rivaroxaban. Blood samples from healthy volunteers were spiked with rivaroxaban to test the correlation between rivaroxaban concentration and coagulation tests. Patient blood samples were spiked with various concentrations of the above-mentioned agents and analysed using thromboelastometry and thrombin generation.

Results

When added in vitro, rivaroxaban was significantly (P<0.05) correlated with ROTEM^® thromboelastometry EXTEM (extrinsic coagulation pathway) clotting time (CT), time to maximal velocity (MaxV−t), and with all measured thrombin generation parameters. In vivo, CT, MaxV−t, lag time, and peak thrombin generation (C_max) were significantly correlated with rivaroxaban concentrations. Regarding reversal of rivaroxaban, all tested agents significantly (P<0.05) reduced EXTEM CT, but to different extents: rFVIIa by 68%, aPCC by 47%, PCC by 17%, and FI by 9%. Only rFVIIa reversed EXTEM CT to baseline values. Both PCC (+102%) and aPCC (+232%) altered overall thrombin generation (area under the curve) and increased C_max (+461% for PCC, +87.5% for aPCC).

Conclusions

Thromboelastometry and thrombin generation assays do not favour the same reversal agents for rivaroxaban anticoagulation. Controlled clinical trials are urgently needed to establish doses and clinical efficacy of potential reversal agents.

Clinical trial registration

EudracCT trial no. 213-00474-30.

Neutralizing blood-borne polyphosphate in vivo provides safe thromboprotection

Polyphosphate is an inorganic procoagulant polymer. Here we develop specific inhibitors of polyphosphate and show that this strategy confers thromboprotection in a factor XII-dependent manner. Recombinant Escherichia coli exopolyphosphatase (PPX) specifically degrades polyphosphate, while a PPX variant lacking domains 1 and 2 (PPX_Δ12) binds to the polymer without degrading it. Both PPX and PPX_Δ12 interfere with polyphosphate- but not tissue factor- or nucleic acid-driven thrombin formation. Targeting polyphosphate abolishes procoagulant platelet activity in a factor XII-dependent manner, reduces fibrin accumulation and impedes thrombus formation in blood under flow. PPX and PPX_Δ12 infusions in wild-type mice interfere with arterial thrombosis and protect animals from activated platelet-induced venous thromboembolism without increasing bleeding from injury sites. In contrast, targeting polyphosphate does not provide additional protection from thrombosis in factor XII-deficient animals. Our data provide a proof-of-concept approach for combating thrombotic diseases without increased bleeding risk, indicating that polyphosphate drives thrombosis via factor XII.

The inorganic procoagulant polymer polyphosphate participates in thrombosis via factor XII. Here the authors use recombinant probes that specifically bind or degrade circulating polyphosphate to protect mice in arterial and venous thrombosis models without an increased bleeding risk, the primary complication of all currently used anticoagulants.

Interactions between depolymerized fucosylated glycosaminoglycan and coagulation proteases or inhibitors

Fucosylated glycosaminoglycan (FG) is a structurally novel glycosaminoglycan derivative, and it has potent anticoagulant activity. Depolymerized FG (dFG) is a selective factor Xase (FXase, FIXa-FVIIIa complex) inhibitor and it has antithrombotic action without major bleeding risks. In this study, we report the effects of dFG-3 (Mw ~14kDa) on the catalysis rates of factor IIa (FIIa), factor Xa (FXa) and factor IXa (FIXa) inhibition by antithrombin (AT), and the kinetic of the interactions between coagulation proteases or inhibitors and dFG-3 were also studied using biolayer interferometry (BLI) technology. We found that dFG-3 had much weaker catalysis activity of coagulation proteases inhibition by AT compared with heparin (UFH). The binding affinity of AT bound to dFG-3 was lower than UFH, and the UFH-AT interaction fitted well with biphasic-binding model while dFG-3-AT interaction was monophasic-binding, suggesting dFG-3 might not have allosteric activation effect on AT. The results are consistent with AT-independent inhibitory activities of dFG-3. dFG-3 could strongly bind to FIXa with much higher affinity than UFH, further explained the reason for its potent FXase inhibitory activity. Additionally, the binding ability of dFG-3 and FIXa decreased with decreasing molecular, and the fucose side chains and carboxyl groups of dFG-3 might be required for its high affinity binding with FIXa. Our data supports further the investigation of dFG-3 as a promising anticoagulant drug inhibiting the intrinsic FXase by binding to FIXa.

Pathogenesis, Diagnosis, and Treatment of Venous Thromboembolism in Older Adults

Older adults have a significantly greater risk of venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism, than younger adults. The cause of this greater risk is thought to be multifactorial, including age-related changes in hemostatic factors and greater comorbid conditions and hospitalizations, but is not completely understood. Moreover, VTE remains underrecognized in older adults and may present atypically. Thus, a low index of clinical suspicion is essential when evaluating older adults with possible VTE. Despite this underrecognition in older adults, the diagnostic approach remains similar for all age groups and includes estimation of pretest probability, measurement of the D-dimer, and imaging. Antithrombotic agents are the mainstay of VTE treatment and, when used appropriately, substantially reduce VTE recurrence and complications. The approval of novel oral anticoagulants (NOACs), including dabigatran, rivaroxaban, apixaban, and edoxaban, provide clinicians with new therapeutic options. In some individuals, NOACs may offer advantages over warfarin, including fewer drug interactions, more-predictable anticoagulation, and lower risk of bleeding. Nevertheless, anticoagulation of VTE in older adults should always be performed cautiously, because age is a risk factor for bleeding complications. Identifying modifiable bleeding risk factors and balancing the risks of VTE recurrence with hemorrhage are important considerations when using anticoagulants in older adults.

Cerebral Venous Thrombosis: Current and Newer Anticoagulant Treatment Options

BACKGROUND

Cerebral venous thrombosis (CVT) is rare and involves thrombosis of the veins and sinuses of the brain, most commonly the superior sagittal sinus. Approximately 5 CVT cases occur per 1 million persons in western countries. CVT causes 0.5% of strokes. Early diagnosis is crucial to prevent such outcomes as hydrocephalus, intracranial hypertension, and further seizures. Standard medical treatment of CVT consists of low-molecular-weight heparin and endovascular thrombolysis. Small case reports have found that the newer oral anticoagulants can be used for CVT treatment; however, they are associated with increased risk of bleeding and other adverse effects.

REVIEW SUMMARY

CVT can be triggered by an imbalance of the body's homeostasis or reduced action of the intrinsic antithrombotic mechanism. Factors influencing this change include infection, brain tumor, inflammatory conditions, genetic thrombophilias, head trauma that causes intracranial bleeding, and certain medications. CVT may cause brain infarction and increased intracranial pressure. Sometimes, idiopathic intracranial hypertension presents as the only clinical manifestation. Confirmation of the diagnosis typically is through neuroimaging. Current CVT treatment depends on disease extent and severity.

CONCLUSIONS

CVT is a rare neurological disease with potentially serious implications and high neurological morbidity and mortality rates. Understanding the role of risk factors-such as genetic or acquired thrombophilia, pregnancy, use of oral contraceptives, and hyperhomocysteinemia-in CVT development is important. Although heparin and warfarin have been used for more than 50 years, newer oral anticoagulants (eg, dabigatran, rivaroxaban, apixaban) might offer an alternative to traditional therapy.

Novel Oral Anticoagulants in Atrial Fibrillation: Update on Apixaban

Almost 800,000 new or recurrent strokes occur every year. Atrial fibrillation, the most common cardiac arrhythmia, is a major risk factor for stroke, accounting for 15-20% of ischemic strokes. Apixaban is a direct inhibitor of Factor Xa that was approved in December 2012 by the US Food and Drug Administration (FDA) for the prevention of stroke in patients with non-valvular atrial fibrillation. It is part of a family of novel oral anticoagulants (NOACs) which has advantage over warfarin of less dosing variability, rapid onset of action and no INR monitoring required. Apixaban showed superiority to warfarin in both primary efficacy and primary safety outcomes by simultaneously showing both significantly lower rates of strokes and systemic embolism and a reduced risk of major clinical bleeding in clinical trials. Warfarin remains the anticoagulant of choice for patients with prosthetic heart valves and significant mitral stenosis. There are currently no head-to-head studies that directly compare the different NOACs with one another, but it is expected that there will be more trials in the future that will explore this comparison. Dabigatran is the only NOAC with an FDA approved reversal agent. However, a reversal agent for apixaban is being developed and was successful in recent clinical trials. This review summarizes the clinical trial data on apixaban for atrial fibrillation, compares apixaban to other NOACs and discusses apixaban use in clinical practice.

Uso de los anticoagulantes orales directos en la práctica clínica

<p>Los anticoagulantes orales directos surgieron en respuesta a la búsqueda de un anticoagulante ideal después de que la warfarina fuera por mucho tiempo el único disponible. Los inhibidores del factor X activado —rivaroxabán y apixabán— y el inhibidor de trombina —dabigatrán etexilato— ya están aprobados en Colombia. Estos grupos farmacológicos están indicados en la tromboprofilaxis luego de artroplastia de rodilla y cadera, en la prevención del accidente cerebrovascular y el embolismo sistémico en pacientes con fibrilación auricular no valvular y en el tratamiento del tromboembolismo venoso. La aprobación de los inhibidores se dio luego de mostrar eficacia y seguridad al compararse con warfarina y enoxaparina. Entre las ventajas que estos presentan figuran las siguientes: inicio rápido de acción, efecto predecible, poca variabilidad interindividual que elimina la necesidad de la monitorización frecuente y menos interacciones medicamentosas; pero, al igual que en la warfarina, el sangrado es el principal evento adverso. El objetivo de esta revisión es conocer la farmacología de los anticoagulantes orales directos aprobados en Colombia, los resultados de los ensayos clínicos que respaldan su uso, la dosificación, el uso perioperatorio y el cambio entre anticoagulantes; situaciones que plantean particularidades para cada uno.</p>

Direct Oral Anticoagulants for the Management of Thromboembolic Disorders

Anticoagulation therapy is central to the management of thromboembolic disorders, and the use of direct oral anticoagulants offers several advantages over standard therapy with parenteral heparins and vitamin K antagonists. In phase III clinical trials, the direct oral anticoagulants (given once or twice daily) all demonstrated favorable benefit–risk profiles compared with conventional standard therapy for the treatment and secondary prevention of venous thromboembolism and for stroke prevention in patients with nonvalvular atrial fibrillation. In clinical practice, many factors may influence overall clinical outcomes in patients receiving anticoagulant therapy, including adherence and persistence to the prescribed therapy, which becomes particularly important during long-term therapy. When choosing an anticoagulant for an individual patient, the pharmacological and clinical profile of the anticoagulant, its dosing regimen, and the patient’s clinical characteristics (eg, renal function and comorbidities) and preferences should be considered. This review examines the rationale for and clinical evidence of the selected dosing regimens of the direct oral anticoagulants for the treatment of venous thromboembolism and stroke prevention in nonvalvular atrial fibrillation. The potential influence of dosing strategies (eg, once- or twice-daily dosing) and other factors on patient adherence and therapy persistence are also discussed.

Update on Anticoagulation: What the Interventional Radiologist Needs to Know

The novel oral anticoagulants (NOACs) represent a major advance in the treatment of patients with nonvalvular atrial fibrillation and venous thromboembolism (VTE). They have several advantages over vitamin-K antagonists such as warfarin, including more predictable pharmacokinetics and improved safety, particularly with fatal bleeding and intracranial hemorrhage. However, several issues remain surrounding the use of NOACs in certain subpopulations and with the approach to reversal. The periprocedural management of anticoagulation with these relatively new agents can also present several challenges. This article reviews the basic pharmacology, efficacy, and safety of these drugs. Several populations at higher risk for complications with use of NOACs are discussed, including those undergoing procedures. Finally, several target-specific reversal agents have either received FDA approval or likely will be approved in the near future; these agents and their roles in the approach to anticoagulation reversal will also be discussed.