Reversing the anticoagulation effects of dabigatran

Endoscopic diagnosis and management of nonvariceal upper gastrointestinal hemorrhage (NVUGIH): European Society of Gastrointestinal Endoscopy (ESGE) Guideline - Update 2021

1: ESGE recommends in patients with acute upper gastrointestinal hemorrhage (UGIH) the use of the Glasgow-Blatchford Score (GBS) for pre-endoscopy risk stratification. Patients with GBS ≤ 1 are at very low risk of rebleeding, mortality within 30 days, or needing hospital-based intervention and can be safely managed as outpatients with outpatient endoscopy.Strong recommendation, moderate quality evidence. 2: ESGE recommends that in patients with acute UGIH who are taking low-dose aspirin as monotherapy for secondary cardiovascular prophylaxis, aspirin should not be interrupted. If for any reason it is interrupted, aspirin should be re-started as soon as possible, preferably within 3-5 days.Strong recommendation, moderate quality evidence. 3: ESGE recommends that following hemodynamic resuscitation, early (≤ 24 hours) upper gastrointestinal (GI) endoscopy should be performed. Strong recommendation, high quality evidence. 4: ESGE does not recommend urgent (≤ 12 hours) upper GI endoscopy since as compared to early endoscopy, patient outcomes are not improved. Strong recommendation, high quality evidence. 5: ESGE recommends for patients with actively bleeding ulcers (FIa, FIb), combination therapy using epinephrine injection plus a second hemostasis modality (contact thermal or mechanical therapy). Strong recommendation, high quality evidence. 6: ESGE recommends for patients with an ulcer with a nonbleeding visible vessel (FIIa), contact or noncontact thermal therapy, mechanical therapy, or injection of a sclerosing agent, each as monotherapy or in combination with epinephrine injection. Strong recommendation, high quality evidence. 7 : ESGE suggests that in patients with persistent bleeding refractory to standard hemostasis modalities, the use of a topical hemostatic spray/powder or cap-mounted clip should be considered. Weak recommendation, low quality evidence. 8: ESGE recommends that for patients with clinical evidence of recurrent peptic ulcer hemorrhage, use of a cap-mounted clip should be considered. In the case of failure of this second attempt at endoscopic hemostasis, transcatheter angiographic embolization (TAE) should be considered. Surgery is indicated when TAE is not locally available or after failed TAE. Strong recommendation, moderate quality evidence. 9: ESGE recommends high dose proton pump inhibitor (PPI) therapy for patients who receive endoscopic hemostasis and for patients with FIIb ulcer stigmata (adherent clot) not treated endoscopically. (A): PPI therapy should be administered as an intravenous bolus followed by continuous infusion (e. g., 80 mg then 8 mg/hour) for 72 hours post endoscopy. (B): High dose PPI therapies given as intravenous bolus dosing (twice-daily) or in oral formulation (twice-daily) can be considered as alternative regimens.Strong recommendation, high quality evidence. 10: ESGE recommends that in patients who require ongoing anticoagulation therapy following acute NVUGIH (e. g., peptic ulcer hemorrhage), anticoagulation should be resumed as soon as the bleeding has been controlled, preferably within or soon after 7 days of the bleeding event, based on thromboembolic risk. The rapid onset of action of direct oral anticoagulants (DOACS), as compared to vitamin K antagonists (VKAs), must be considered in this context.Strong recommendation, low quality evidence.

Mortality in relation to presence and type of oral antithrombotic agent among adult trauma patients: a single-center retrospective cohort study

PURPOSE

Oral anticoagulants (AC) and antiplatelet (AP) agents are increasingly prescribed to prevent and treat acute and chronic thrombotic conditions. The direct oral anticoagulants (DOAC), a newer class of AC, raise concerns in the trauma setting. Our study aims to compare the mortality rates and other outcomes among adult trauma patients based on pre-admission AC/AP status.

METHODS

We conducted a retrospective cohort study of a prospectively collected database of trauma patients previously on DOAC, warfarin, aspirin or clopidogrel. A matched control group of trauma patients not receiving AC/AP was used for comparison. Our primary endpoint was in-hospital mortality according to antithrombotic medication class. Secondary endpoints included length of stay (LOS), intensive care unit (ICU) admission, need for blood transfusion, and discharge to a dependent setting. Univariate and multivariate analyses were conducted.

RESULTS

There were 996 exposed patients and 234 controls, with no major clinically significant difference among study groups in terms of gender, injury site, injury severity, mechanism, and comorbidities. The mortality rates were 2.14% (control, 5/234), 2.88% (DOAC, 3/104), 3.34% (aspirin, 17/509), 7.63% (warfarin, 18/236), 9% (clopidogrel, 8/89), and 13.79% (aspirin + clopidogrel, 8/58) (p < 0.001). In multivariate analyses, there was no difference regarding mortality between DOAC and reference groups. Blood transfusion was more likely in patients receiving warfarin or AP than those prescribed DOAC.

CONCLUSION

There was no evidence of increased mortality or blood transfusion requirement among trauma patients on DOAC, including head trauma patients. Further studies on head trauma and specific subgroups of DOAC are recommended.

Genetic determinants of dabigatran safety (CES1 gene rs2244613 polymorphism) in the Russian population: multi-ethnic analysis

This study was aimed to investigate the prevalence of the CES1 gene (c.1168-33A > C, rs2244613) polymorphism among 12 different ethnic groups living in Russia to provide a basis for future clinical studies concerning genetic determinants of dabigatran safety. The study involved 1630 apparently healthy, unrelated, and chronic medication-free volunteers of both genders from 12 different ethnic groups in Russia: 136 Russians, 90 Avars, 50 Dargins, 46 Laks, 120 Kabardians, 112 Balkars, 244 Ossetians, 206 Mari, 204 Mordvinians, 238 Chuvashes, 114 Buryats and 70 Nanays. Genotyping was performed by using real-time polymerase chain reaction-based methods. The allelic prevalence of the ethnic groups was compared with Caucasus population participating in the RE-LY study. Statistically significant differences for the following gene polymorphism were found between all ethnic groups and RE-LY participants. Based on obtained results, it can be assumed that patients of all ethnic groups living in Russia taking dabigatran have a lower risk of bleeding.

Thrombin Exosite Maturation and Ligand Binding at ABE II Help Stabilize PAR-Binding Competent Conformation at ABE I

Thrombin, derived from zymogen prothrombin (ProT), is a serine protease involved in procoagulation, anticoagulation, and platelet activation. Thrombin's actions are regulated through anion-binding exosites I and II (ABE I and ABE II) that undergo maturation during activation. Mature ABEs can utilize exosite-based communication to fulfill thrombin functions. However, the conformational basis behind such long-range communication and the resultant ligand binding affinities are not well understood. Protease activated receptors (PARs), involved in platelet activation and aggregation, are known to target thrombin ABE I. Unexpectedly, PAR3 (44-56) can already bind to pro-ABE I of ProT. Nuclear magnetic resonance (NMR) ligand-enzyme titrations were used to characterize how individual PAR1 (49-62) residues interact with pro-ABE I and mature ABE I. 1D proton line broadening studies demonstrated that binding affinities for native PAR1P (49-62, P54) and for the weak binding variant PAR1G (49-62, P54G) increased as ProT was converted to mature thrombin. ¹H,¹⁵N-HSQC titrations revealed that PAR1G residues K51, E53, F55, D58, and E60 exhibited less affinity to pro-ABE I than comparable residues in PAR3G (44-56, P51G). Individual PAR1G residues then displayed tighter binding upon exosite maturation. Long-range communication between thrombin exosites was examined by saturating ABE II with phosphorylated GpIbα (269-282, 3Yp) and monitoring the binding of PAR1 and PAR3 peptides to ABE I. Individual PAR residues exhibited increased affinities in this dual-ligand environment supporting the presence of interexosite allostery. Exosite maturation and beneficial long-range allostery are proposed to help stabilize an ABE I conformation that can effectively bind PAR ligands.

Pharmacogenomics of Novel Direct Oral Anticoagulants: Newly Identified Genes and Genetic Variants

Direct oral anticoagulants (DOAC) have shown an upward prescribing trend in recent years due to favorable pharmacokinetics and pharmacodynamics without requirement for routine coagulation monitoring. However, recent studies have documented inter-individual variability in plasma drug levels of DOACs. Pharmacogenomics of DOACs is a relatively new area of research. There is a need to understand the role of pharmacogenomics in the interpatient variability of the four most commonly prescribed DOACs, namely dabigatran, rivaroxaban, apixaban, and edoxaban. We performed an extensive search of recently published research articles including clinical trials and in-vitro studies in PubMed, particularly those focusing on genetic loci, single nucleotide polymorphisms (SNPs), and DNA polymorphisms, and their effect on inter-individual variation of DOACs. Additionally, we also focused on commonly associated drug-drug interactions of DOACs. CES1 and ABCB1 SNPs are the most common documented genetic variants that contribute to alteration in peak and trough levels of dabigatran with demonstrated clinical impact. ABCB1 SNPs are implicated in alteration of plasma drug levels of rivaroxaban and apixaban. Studies conducted with factor Xa, ABCB1, SLCOB1, CYP2C9, and VKORC1 genetic variants did not reveal any significant association with plasma drug levels of edoxaban. Pharmacokinetic drug-drug interactions of dabigatran are mainly mediated by p-glycoprotein. Strong inhibitors and inducers of CYP3A4 and p-glycoprotein should be avoided in patients treated with rivaroxaban, apixaban, and edoxaban. We conclude that some of the inter-individual variability of DOACs can be attributed to alteration of genetic variants of gene loci and drug-drug interactions. Future research should be focused on exploring new genetic variants, their effect, and molecular mechanisms that contribute to alteration of plasma levels of DOACs.

Pharmacogenetics of novel oral anticoagulants: a review of identified gene variants & future perspectives

Novel oral anticoagulants (NOACs) are becoming a therapy of choice in everyday clinical practice after almost 50 years during which warfarin and related coumarin derivatives were used as the main anticoagulants. Advantages of NOACs over standard anticoagulants include their predictable pharmacodynamics and pharmacokinetics, stable plasma concentrations and less drug-drug and food-drug interactions. However, pharmacogenetics has its place in administration of NOACs, as considerable interindividual variations have been detected. In this review, previous findings in pharmacogenetics of dabigatran, rivaroxaban, apixaban and edoxaban are summarized, along with recommendations for studying genes encoding metabolically important enzymes for four selected NOACs. Future directions include identification of clinically relevant SNPs, and change in optimum dosage for patients who are carriers of significant variants.

Non-variceal upper gastrointestinal bleeding

Non-variceal upper gastrointestinal bleeding (NVUGIB) is bleeding that develops in the oesophagus, stomach or proximal duodenum. Peptic ulcers, caused by Helicobacter pylori infection or use of NSAIDs and low-dose aspirin (LDA), are the most common cause. Although the incidence and mortality associated with NVUGIB have been decreasing owing to considerable advances in the prevention and management of NVUGIB over the past 20 years, it remains a common clinical problem with an annual incidence of ∼67 per 100,000 individuals in the United States in 2012. NVUGIB is a medical emergency, and mortality is in the range ∼1-5%. After resuscitation and initial assessment, early (within 24 hours) diagnostic and therapeutic endoscopy together with intragastric pH control with proton pump inhibitors (PPIs) form the basis of treatment. With a growing ageing population treated with antiplatelet and/or anticoagulant medications, the clinical management of NVUGIB is complex as the risk between gastrointestinal bleeding events and adverse cardiovascular events needs to be balanced. The best clinical approach includes identification of risk factors and prevention of bleeding; available strategies include continuous treatment with PPIs or H. pylori eradication in those at increased risk of developing NVUGIB. Treatment with PPIs and/or use of cyclooxygenase-2-selective NSAIDs should be implemented in those patients at risk of NVUGIB who need NSAIDs and/or LDA.

Deciphering Conformational Changes Associated with the Maturation of Thrombin Anion Binding Exosite I

Thrombin participates in procoagulation, anticoagulation, and platelet activation. This enzyme contains anion binding exosites, ABE I and ABE II, which attract regulatory biomolecules. As prothrombin is activated to thrombin, pro-ABE I is converted into mature ABE I. Unexpectedly, certain ligands can bind to pro-ABE I specifically. Moreover, knowledge of changes in conformation and affinity that occur at the individual residue level as pro-ABE I is converted to ABE I is lacking. Such changes are transient and were not captured by crystallography. Therefore, we employed nuclear magnetic resonance (NMR) titrations to monitor development of ABE I using peptides based on protease-activated receptor 3 (PAR3). Proton line broadening NMR revealed that PAR3 (44-56) and more weakly binding PAR3G (44-56) could already interact with pro-ABE I on prothrombin. ¹H-¹⁵N heteronuclear single-quantum coherence NMR titrations were then used to probe binding of individual ¹⁵N-labeled PAR3G residues (F47, E48, L52, and D54). PAR3G E48 and D54 could interact electrostatically with prothrombin and tightened upon thrombin maturation. The higher affinity for PAR3G D54 suggests the region surrounding thrombin R77a is better oriented to bind D54 than the interaction between PAR3G E48 and thrombin R75. Aromatic PAR3G F47 and aliphatic L52 both reported on significant changes in the chemical environment upon conversion of prothrombin to thrombin. The ABE I region surrounding the 30s loop was more affected than the hydrophobic pocket (F34, L65, and I82). Our NMR titrations demonstrate that PAR3 residues document structural rearrangements occurring during exosite maturation that are missed by reported X-ray crystal structures.

Immediate versus delayed surgery for hip fractures in the elderly patients: a protocol for a systematic review and meta-analysis

BACKGROUND

Hip fractures are a major public health problem in elderly populations and are accompanied by high-mortality rates. Whether timing of surgery has an impact on morbidity and mortality has been discussed controversially, numerous studies suggest that the delay of surgery can significantly increase the risk of morbidity and mortality; others report that achieving a stable medical condition is more important than early surgery. The goal of our systematic review is to assess the impact of timing of surgery on health outcomes in patients aged 60 years or older with acute hip fracture. In addition, we will investigate differences in beneficial or harmful effects of timing of surgery in subgroups of patients based on demographic characteristics, physical status, and the use of anticoagulant medications.

METHODS

We will systematically search MEDLINE via Ovid, the Cochrane Library, Embase, PubMed, and clinical trial registries (from 1997 to 2017). In addition, we will search reference lists of pertinent reviews, archives of annual meetings of orthopaedic societies, and contact experts. We will include randomized controlled trials and non-randomized studies assessing the impact of timing of surgery after hip fracture in patients 60 years or older, published in English or German. Our outcomes of interest include health outcomes such as mortality, perioperative complications, functional capacity, and quality of life. We plan to perform meta-analyses if we have at least three sufficiently similar studies. If data are sufficient, we will conduct subgroup-analyses testing for differences between age groups, sex, patients' physical status as assessed with ASA (American Society of Anesthesiologists) scores, and the use of anticoagulation.

DISCUSSION

Since this is the first systematic review on this topic since 2010, our findings will help to inform clinical practice guidelines concerning timing of surgery in hip fractures. Furthermore, our findings could contribute to define an optimal time period for surgery for different groups of patients with acute hip fracture.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2017 CRD42017058216.