Factor Xa Inhibitors Research Articles

A small-molecule hemostatic agent for the reversal of direct oral anticoagulant–induced bleeding

BackgroundThe bleeding risk associated with direct oral anticoagulants (DOACs) remains a major concern, and rapid reversal of anticoagulant activity may be required. Although specific and nonspecific hemostatic biotherapies are available, there is a need for small-molecule DOAC reversal agents that are simple and cost-effective to produce, store, and administer. ObjectivesTo identify and characterize a small molecule with procoagulant activity as a DOAC reversal agent. MethodsWe sought to identify a small procoagulant molecule by screening a chemical library with a plasma clotting assay. The selected molecule was assessed for its procoagulant properties and its ability to reverse the effects of the DOACs in a thrombin generation assay. Its activity as a DOAC reversal agent was also evaluated in a tail-clip bleeding assay in mice. ResultsThe hemostatic molecule (HeMo) dose-dependently promoted thrombin generation in plasma, with dose values effective in producing half-maximum response ranging between 3 and 5 μM, depending on the thrombin generation assay parameter considered. HeMo also restored impaired thrombin generation in DOAC-spiked plasma and reversed DOAC activity in the mouse bleeding model. HeMo significantly reduced apixaban-induced bleeding from 709 to 65 μL (vs 43 μL in controls; P < .01) and dabigatran-induced bleeding from 989 to 155 μL (vs 126 μL in controls; P < .01). ConclusionHeMo is a small-molecule procoagulant that can counterbalance hemostatic disruption by a thrombin inhibitor (dabigatran) or factor Xa inhibitors (apixaban and rivaroxaban). The compound’s effective clot formation and versatility make it a possible option for managing the inherent hemorrhagic risk during DOAC therapy.

Factor Xa inhibitors vs. warfarin in patients with Hughes syndrome: a systematic review and meta-analysis of randomized controlled trials.

The optimal treatment regimen for patients with Hughes syndrome remains unclear. Therefore, the authors sought to compare the outcomes of warfarin vs. factor Xa inhibitors in patients with Hughes syndrome. MEDLINE, Embase, and Cochrane Central databases were searched for randomized controlled trials (RCTs) comparing 8 efficacy and safety of warfarin and factor Xa inhibitors in patients with Hughes syndrome. Recurrent thrombosis, all-cause mortality, stroke, adverse reactions, and bleeding were among 10 outcomes of interest. Mantel-Haenszel weighted random-effects model was used to calculate 11 relative risks (RRs) with 95% CIs. The analysis included 625 patients from four RCTs and one post-hoc analysis. Meta-analysis showed a statistically non-significant difference between factor Xa inhibitors and warfarin 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 a 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 antibodies (aPL) positive [RR 4.12 (95% CI 0.46, 37.10); 21 P=0.21, I2=58%]. Factor Xa inhibitors were significantly associated with an increased risk of stroke [RR 8.51 (95% CI 2.35, 13.82); P=0.47, I2=0%]. Factor Xa inhibitors exhibited an increased risk of stroke among patients with Hughes syndrome. In addition, although not significant, the higher RRs among patients on factor Xa inhibitors may indicate a higher risk of thrombotic events associated with factor Xa inhibitors.

Bioequivalence of Rivaroxaban Hard Capsules vs. Film-Coated Tablets in Healthy White Volunteers

Rivaroxaban is an oral anticoagulant that is a selective, direct factor Xa inhibitor. It is used to prevent thrombotic events of atherosclerotic etiology and to prevent stroke and peripheral embolism in adult patients with nonvalvular atrial fibrillation. The aim of studies was to assess the bioequivalence of two orally administered products: test (Zarixa hard capsules) vs. reference (Xarelto® film-coated tablets). Two crossover, 2-period, randomized, open-label, laboratory-blinded studies were conducted in healthy White male and female volunteers. A single oral dose (Study 1: 10 mg fasting, Study 2: 20 mg fed) of the test or reference product was followed by a minimum 7-day washout. Blood was collected up to 48 h after administration. Plasma concentrations of rivaroxaban were measured using a validated LC-MS/MS method. The bioequivalence criteria for 90% confidence intervals (CI) of the log-transformed geometric mean ratios (test/reference) for the two primary pharmacokinetic parameters (AUC(0-t) and Cmax) were set at 80.00-125.00%. Vital signs, laboratory parameters, and adverse events were monitored. 34 of 36 volunteers completed Study 1, and geometric mean ratios were 97.96% (90% CI 93.69-102.42%) for AUC(0-t), and 89.35% (90% CI 84.28-94.72%) for Cmax. All 36 volunteers completed Study 2, and geometric mean ratios were 103.57% (90% CI 98.75-108.63%) for AUC(0-t), and 95.17% (90% CI 87.35-103.70%) for Cmax. All of 90% CIs for the primary pharmacokinetic parameter ratios met acceptance criteria. There were no serious adverse events. Results of both studies indicate that the test product (Zarixa) is bioequivalent to the reference product (Xarelto®). Both products were well tolerated.

Ventriculoperitoneal Shunt Placement Safety in Idiopathic Normal Pressure Hydrocephalus: Anticoagulated Versus Non–Anticoagulated Patients

Many patients with idiopathic normal pressure hydrocephalus (iNPH) have medical comorbidities requiring anticoagulation that could negatively impact outcomes. This study evaluated the safety of ventriculoperitoneal shunt (VPS) placement in iNPH patients on systemic anticoagulation versus those not on anticoagulation. Patients > 60 years of age with iNPH who underwent shunting between 2018 and 2022 were retrospectively reviewed. Baseline demographics, comorbidities (quantified by modified Frailty Index (mFI) and Charlson Comorbidity Index (CCI)), anticoagulant/antiplatelet agent use (other than aspirin), operative details, and complications were collected. Outcomes of interest were the occurrence of postoperative hemorrhage and overdrainage. A total of 234 patients were included in the study (mean age 75.22 ± 6.04 years; 66.7% male); 36 were on anticoagulation/antiplatelet therapy (excluding aspirin). This included 6 on Warfarin, 19 on direct Xa inhibitors, 10 on Clopidogrel, and one on both Clopidogrel and Warfarin. Notably, 70% of patients (164/234) used aspirin alone or combined with anticoagulation or clopidogrel. Baseline mFI was similar between groups, but those on anticoagulant/antiplatelet therapy had a higher mean CCI (2.67±1.87 vs. 1.75±1.84; p=0.001). Patients on anticoagulants were more likely to experience tract hemorrhage (11.1 vs. 2.5%; p=0.03), with no significant difference in the rates of intraventricular hemorrhage or overdrainage related subdural fluid collection. Anticoagulant and antiplatelet agents are common in the iNPH population, and patients on these agents experienced higher rates of tract hemorrhage following VPS placement; however, overall hemorrhagic complication rates were similar.

Clinical guideline on reversal of direct oral anticoagulants in patients with life threatening bleeding.

Anticoagulation is essential for the treatment and prevention of thromboembolic events. Current guidelines recommend direct oral anticoagulants (DOACs) over vitamin K antagonists in DOAC-eligible patients. The major complication of anticoagulation is serious or life-threatening haemorrhage, which may necessitate prompt haemostatic intervention. Reversal of DOACs may also be required for patients in need of urgent invasive procedures. This guideline from the European Society of Anaesthesiology and Intensive Care (ESAIC) aims to provide evidence-based recommendations and suggestions on how to manage patients on DOACs undergoing urgent or emergency procedures including the treatment of DOAC-induced bleeding. A systematic literature search was performed, examining four drug comparators (dabigatran, rivaroxaban, apixaban, edoxaban) and clinical scenarios ranging from planned to emergency surgery with the outcomes of mortality, haematoma growth and thromboembolic complications. The GRADE (Grading of Recommendations, Assessment, Development and Evaluation) methodology was used to assess the methodological quality of the included studies. Consensus on the wording of the recommendations was achieved by a Delphi process. So far, no results from prospective randomised trials comparing two active comparators (e.g. a direct reversal agent and an unspecific haemostatic agent such as prothrombin complex concentrate: PCC) have been published yet and the majority of publications were uncontrolled and observational studies. Thus, the certainty of evidence was assessed to be either low or very low (GRADE C). Thirty-five recommendations and clinical practice statements were developed. During the Delphi process, strong consensus (>90% agreement) was achieved in 97.1% of recommendations and consensus (75 to 90% agreement) in 2.9%. DOAC-specific coagulation monitoring may help in patients at risk for elevated DOAC levels, whereas global coagulation tests are not recommended to exclude clinically relevant DOAC levels. In urgent clinical situations, haemostatic treatment using either the direct reversal or nonspecific haemostatic agents should be started without waiting for DOAC level monitoring. DOAC levels above 50 ng ml-1 may be considered clinically relevant necessitating haemostatic treatment before urgent or emergency procedures. Before cardiac surgery under activated factor Xa (FXa) inhibitors, the use of andexanet alfa is not recommended because of inhibition of unfractionated heparin, which is needed for extracorporeal circulation. In the situation of DOAC overdose without bleeding, no haemostatic intervention is suggested, instead measures to eliminate the DOACs should be taken. Due to the lack of published results from comparative prospective, randomised studies, the superiority of reversal treatment strategy vs. a nonspecific haemostatic treatment is unclear for most urgent and emergency procedures and bleeding. Due to the paucity of clinical data, no recommendations for the use of recombinant activated factor VII as a nonspecific haemostatic agent can be given. In the clinical scenarios of DOAC intake before urgent procedures and DOAC-induced bleeding, practitioners should evaluate the risk of bleeding of the procedure and the severity of the DOAC-induced bleeding before initiating treatment. Optimal reversal strategy remains to be determined in future trials for most clinical settings.

Efficacy and safety of oral factor Xa inhibitors versus vitamin-K antagonists in the early phase after acute ischemic stroke or TIA in the real-world setting: The PRODAST study.

Factor Xa (FXa) inhibitors are superior to vitamin K antagonists (VKAs) in terms of avoiding hemorrhagic complications. However, no robust data are available to date as to whether this also applies to the early phase after stroke. In this prospective registry study, we aimed to investigate whether anticoagulation with FXa inhibitors in the early phase after acute ischemic stroke or transient ischemic attack (TIA) is associated with a lower risk of major bleeding events compared with VKAs. The Prospective Record of the Use of Dabigatran in Patients with Acute Stroke or TIA (PRODAST) study is a prospective, multicenter, observational, post-authorization safety study at 86 German stroke units between July 2015 and November 2020. Primary outcome was a major bleeding event during hospital stay. Secondary endpoints were recurrent strokes, recurrent ischemic strokes, TIA, systemic/pulmonary embolism, myocardial infarction, death and the composite endpoint of stroke, systemic embolism, life-threatening bleeding and death. In total, 10,039 patients have been recruited. 5,874 patients were treated with FXa inhibitors and 1,050 patients received VKAs and were eligible for this analysis. Overall, event rates were low. We observed 49 major bleeding complications during 33,297 treatment days with FXa-inhibitors (rate of 14.7 cases per 10,000 treatment days) and 16 cases during 7,714 treatment days with VKAs (rate of 20.7 events per 10,000 treatment days), translating into an adjusted hazard ratio (aHR) of 0.70 (95% confidence interval (95% CI): 0.37-1.32) in favor of FXa inhibitors. Hazards for ischemic endpoints (63 vs 17 strokes, aHR: 0.96 (95% CI: 0.53-1.74), mortality (33 vs 6 deaths, aHR: 0.87 (95% CI: 0.33-2.34)) and the combined endpoint (154 vs 39 events, aHR: 0.99 (95% CI: 0.65-1.41) were not substantially different. This large real-world study shows that FXa inhibitors appear to be similarly effective in terms of bleeding events and ischemic endpoints compared to VKAs in the early post-stroke phase of hospitalization. However, the results need to be interpreted with caution due to the low precision of the estimates.

Clinical Pathways and Outcomes of Andexanet Alfa Administration for the Reversal of Critical Bleeding in Patients on Oral Direct Factor Xa Inhibitors.

Background Andexanet is U.S. Food and Drug Administration (FDA) approved for the reversal of critical bleeding from factor Xa inhibitors and off-label for surgical reversal. Data are lacking on andexanet administration processes. Methods We retrospectively studied patients at a 23-hospital system who received andexanet from November 2019 to March 2023. Abstractors coded demographics, comorbidities, anticoagulant use, andexanet indication, and process times. The primary outcome was presentation-to-andexanet time; diagnosis, ordering, and administration times were calculated. Secondary outcomes included in-hospital postandexanet major thromboembolism/bleeding and mortality. Results In total, 141 patients were analyzed. Andexanet indications were predominantly neurologic bleeding (85.8%). Twenty-four patients (17.0%) were transferred from nontertiary/academic centers to tertiary/academic centers. The median presentation-to-administration time was 192.5 minutes (interquartile range [IQR]: 108.0-337.0 minutes). Components were as follows: 72.5 minutes (IQR: 39.0-137.5 minutes) for bleeding diagnosis; 35.5 minutes (IQR: 0-96.5 minutes) for andexanet ordering; and 53.0 minutes (IQR: 38.5-78.5 minutes) for administration, which was longer at tertiary/academic hospitals (ratio 1.5, 95% confidence interval [CI]: 1.2-2.0, p = 0.002). Gastrointestinal or other critical bleeding (ratio 2.59, 95% CI: 1.67-4.02, p < 0.001), and tertiary/academic center treatment (ratio 1.58, 95% CI: 1.15-2.18, p = 0.005), were associated with increased time. Major thromboembolism, bleeding, and mortality occurred in 10.6, 12.0, and 22.9% of patients, respectively. Conclusions In our cohort, the median presentation-to-administration time was over 3 hours. Cumulative times were longer at tertiary/academic hospitals and for gastrointestinal/other bleeding. Postandexanet major thromboembolism/bleeding occurred more at tertiary/academic hospitals, possibly related to transfers. Prospective studies may elucidate clinical decision-making bottlenecks.

Ex Vivo Antiplatelet Effects of Oral Anticoagulants.

The impact of non-vitamin K antagonist oral anticoagulants (NOACs) on platelet function is still unclear. We conducted a comprehensive ex vivo study aimed at assessing the effect of the four currently marketed NOACs on platelet function. We incubated blood samples from healthy donors with concentrations of NOACs (50, 150 and 250 ng/mL), in the range of those achieved in the plasma of patients during therapy. We evaluated generation of thrombin; light transmittance platelet aggregation (LTA) in response to adenosine diphosphate (ADP), thrombin receptor-activating peptide (TRAP), human γ-thrombin (THR) and tissue factor (TF); generation of thromboxane (TX)B2; and expression of protease-activated receptor (PAR)-1 and P-selectin on the platelet surface. All NOACs concentration-dependently reduced thrombin generation compared with control. THR-induced LTA was suppressed by the addition of dabigatran at any concentration, while TF-induced LTA was reduced by factor-Xa inhibitors. ADP- and TRAP-induced LTA was not modified by NOACs. TXB2 generation was reduced by all NOACs, particularly at the highest concentrations. We found a concentration-dependent increase in PAR-1 expression after incubation with dabigatran, mainly at the highest concentrations, but not with FXa inhibitors; P-selectin expression was not changed by any drugs. Treatment with the NOACs is associated with measurable ex vivo changes in platelet function, arguing for antiplatelet effects beyond the well-known anticoagulant activities of these drugs. There are differences, however, among the NOACs, especially between dabigatran and the FXa inhibitors.

Exploring the effects of Factor Xa inhibitors on thrombin generation in people with haemophilia

Optimal management of cardiovascular disease (CVD) in people with haemophilia (PWH) is a growing issue, given the continuing improvement in life expectancy among PWH. The evolving treatment paradigms targeting higher trough levels and the advent of non-factor replacement therapies (NFRT) means much of the ‘protection’ PWH were thought to have against CVD may be lost. There is a paucity of evidence regarding the safety of using anticoagulants in PWH. We designed a study assessing the thrombin generation (TG) of PWH of different severities and treatments, compared to non-haemophilia patients receiving a Factor Xa (FXa) inhibitor (apixaban or rivaroxaban), healthy controls, and assessing TG parameters of adding FXa inhibitor to the plasma of PWH receiving emicizumab prophylaxis. In total, 40 patients were included. TG was initiated with 5pM tissue factor (TF) using the calibrated automated thrombinoscope. Compared to those with mild haemophilia, patients receiving a FXa inhibitor had higher endogenous thrombin potential (ETP) (1278.42 vs 1831.36) and velocity index (40.71 vs 112.56), but both had a similar peak height (154.0 vs 262.63) and time to peak (both 5.83). People with severe haemophilia receiving emicizumab had significantly improved TG parameters compared to those not receiving emicizumab – ETP 1678.11 vs 809.96 and peak height 233.8 vs 92.05; however, when FXa inhibitor was added their TG parameters deteriorated to the severe haemophilia range (ETP 1179.60 and peak height 103.05). TG may provide additional useful information regarding the use of anticoagulants in PWH.

The Effect of 4-Factor Prothrombin Complex Concentrate to Reverse Factor Xa Inhibitors in Patients With Traumatic Intracranial Hemorrhage.

The utility of 4-factor prothrombin complex concentrate (4F-PCC) for reversal in patients on factor Xa inhibitors (XaI) is unclear, specifically in mild traumatic brain injury (mTBI). This is a retrospective review over 6 years at a level 1 trauma center of patients presenting with mTBI on XaI comparing outcomes for those that received 4F-PCC to those that did not. 140 patients were included, 103 (74%) of these patients received 4F-PCC while 37 (26%) did not. There was no significant difference in neurologic decline within 48 hours of admission or need for neurosurgical intervention. Interestingly, there was no difference in ICH progression (16% vs 14%, P = .77). In this study, 4F-PCC given after mild traumatic brain injury did not impact ICH progression, neurologic decline, or need for neurosurgical intervention. Although limited in numbers, this study suggests that 4F-PCC is not necessarily required in mTBI and further studies are indicated.

A common protein C inhibitor exosite partially controls the heparin induced activation and inhibition of serine proteases

Protein C inhibitor (PCI) maintains hemostasis by inhibiting both procoagulant and anticoagulant serine proteases, and plays important roles in coagulation, fibrinolysis, reproduction, and anti-angiogenesis. The reactive site loop of PCI traps and irreversibly inhibits the proteases like APC (activating protein C), thrombin (FIIa) and factor Xa (FXa). Previous studies on antithrombin (ATIII) had identified Tyr253 and Glu255 as functional exosites that interact and aid in the inhibition of factor IXa and FXa. Presence of exosite in PCI is not known, however a sequence comparison with the PCI from different vertebrate species and ATIII identified Glu239 to be absolutely conserved. PCI residues analogous to ATIII exosite residues were mutated to R238A and E239A. Purified variant PCI in the presence of heparin (10 μg/ml) showed a 2–4 fold decrease in the rate of inhibition of the proteases. However, the stoichiometry of inhibition of FIIa, APC, and FXa by native PCI, R238A and E239A variants were found to be close to 1.0, which also indicated the formation of stable complexes based on SDS-PAGE and western blot analysis with thrombin and APC. Our findings revealed the possible presence of an exosite in PCI that influences the protease inhibition rates.

Factor Xa Inhibitors versus warfarin in patients with morbid obesity and atrial fibrillation.

Factor Xa Inhibitors have emerged as a first-line agent in the management of non-valvular atrial fibrillation (NVAF), but there is a need for additional data surrounding their use in the morbidly obese population. The purpose of this study was to evaluate whether Factor Xa Inhibitors are as safe and effective as warfarin for the treatment of NVAF in individuals with a BMI ≥ 40 kg/m2 and/or weight ≥ 120 kg. This was a multi-center retrospective cohort study comparing the use of Factor Xa Inhibitors (apixaban and rivaroxaban) to warfarin for the management of NVAF in adult patients with a BMI ≥ 40 kg/m2 and/or weight ≥ 120 kg. The primary outcomes were stroke or systemic embolism and major bleeding within 12months. A total of 3,156 patients were included in the final analysis; 1,396 in the warfarin group and 1760 in the Factor Xa Inhibitor group. The mean weight and BMI of the overall cohort was 134.1kg and 44.7kg/m2, respectively. There was no difference in stroke or systemic embolism (OR 1.21, 95% CI 0.78-1.85) or major bleeding (OR 0.99, 95% CI 0.65 - 1.53) with Factor Xa Inhibitors compared to warfarin after controlling for covariates. This analysis of real-world data suggests no difference in bleeding or thrombotic outcomes for severely obese patients with NVAF taking Factor Xa Inhibitors compared to warfarin. Overall, our study adds further data to support the use of Factor Xa Inhibitors as an alternative to warfarin in severely obese patients with NVAF.

Comparative Outcomes of Peripheral Vascular Interventions in Patients on Chronic Anticoagulation with Factor Xa Inhibitors and Vitamin K Antagonists

In patients undergoing revascularization for peripheral arterial disease (PAD), low-dose Factor Xa inhibitors (FXaI) taken with aspirin improved limb and cardiovascular outcomes compared to aspirin alone. Furthermore, in atrial fibrillation and venous thromboembolism, FXaI are recommended over vitamin K antagonists (VKA) for chronic anticoagulation. While studies have evaluated different perioperative anticoagulation regimens in patients treated for PAD, the optimal regimen for chronic anticoagulation in patients with PAD undergoing peripheral vascular intervention (PVI) has not been determined. This analysis compares outcomes of patients after PVI that require chronic anticoagulation with FXaI and VKA. The Vascular Quality Initiative-PVI database was used. Patients consistently treated with FXaI or VKA before the procedure, at discharge, and on long-term follow-up were defined as those receiving chronic anticoagulation. Patient demographics, procedural details, and perioperative and long-term outcomes were compared between FXaI and VKA groups. A total of 109,268 patients were analyzed, and 6,885 were chronically anticoagulated with FXaI (N=2,427) or VKA (N=4,458). Patients anticoagulated with VKA were more frequently males (65.3% vs. 61.0%, P<0.001) with end-stage renal disease (9.7% vs. 4.6%, P<0.001) and more likely to be treated for chronic limb-threatening ischemia (58.1% vs. 52.7%, P<0.001). Rates of hematoma following PVI were significantly higher in patients taking VKA compared to FXaI (3.5% vs. 1.9%, P<0.001). Multivariable logistic regression analysis showed that VKA were associated with increased perioperative hematoma than FXaI (odds ratio=1.89 [1.30-2.82]). Compared to patients taking VKA, those receiving FXaI had lower rates of major amputation (6.7% vs. 8.4%, P=0.020) and mortality (7.6% vs. 15.2%, P ≤ 0.001). Using Kaplan-Meier analysis, patients consistently anticoagulated with FXaI had improved amputation-free survival after PVI. Adjusting for significant patient and procedural characteristics, Cox proportional hazard regression demonstrated that there is an increased risk for major amputation or mortality in patients using VKA compared to FXaI (hazard ratio 1.61, [1.36-1.90]). Chronic anticoagulation with FXaI as compared to VKA was associated with superior perioperative and long-term outcomes in patients with PAD undergoing PVI. FXaI should be the preferred agents over VKA for chronic anticoagulation in patients with PAD undergoing PVI.

Clinical Characteristics and Incidence of Hemorrhagic Complications in Patients Taking Factor Xa Inhibitors in Spain: A Long-Term Observational Study.

Objective. To analyze the clinical characteristics of patients taking Factor Xa inhibitors (FXai), either direct FXai or enoxaparin (only in active cancer patients), and to estimate the incidence of and risk factors for major bleeding during FXai use. Methods. A retrospective cohort study, which included secondary data from computerized health records of primary care centers and hospitals in seven Spanish Autonomous Communities. Results. 9374 patients were analyzed, with 8972 taking direct FXai and 402 enoxaparin. At baseline, the mean age (SD) was 71.8 (9.4) years, 56.0% were women, 76.3% had hypertension, 33.6% had type 2 diabetes, and 25.5% had heart failure. The most common indication for FXai use was atrial fibrillation (72.3%), followed by venous thromboembolism (22.2%) and non-mechanical cardiac-valve replacement (5.6%). At the end of the follow-up period, the incidence rates of major bleeding overall, gastrointestinal, and intracranial were 10.2, 9.0, and 0.8 per 100 person-years, respectively. The total incidence of fatal major bleeding was 0.5 per 100 person-years. Incidence rates of all bleedings progressively decreased over time, with 62.5% of the first events occurring in the initial three months and reaching 76.8% within six months following initiation of treatment. Only 4.8% of the 1st major bleedings led to death, 2.3% in the case of major gastrointestinal bleeding, and 30.8% after an intracranial bleeding. 65.9% of patients discontinued anticoagulation after experiencing major bleeding. Conclusions. In Spain, patients taking FXai were old and had many comorbidities. Despite incidence rates of major bleeding were high, incidence rates of intracranial and fatal bleedings were low, but more efforts are required due to their relevant clinical impact.

Accelerating Factor Xa inhibitor discovery with a de novo drug design pipeline

Accelerating Factor Xa inhibitor discovery with a de novo drug design pipeline

Andexanet alfa versus non-specific treatments for intracerebral hemorrhage in patients taking factor Xa inhibitors - Individual patient data analysis of ANNEXA-4 and TICH-NOAC.

Data comparing the specific reversal agent andexanet alfa with non-specific treatments in patients with non-traumatic intracerebral hemorrhage (ICH) associated with factor-Xa inhibitor (FXaI) use are scarce. The study aimed to determine the association between the use of andexanet alfa compared with non-specific treatments with the rate of hematoma expansion and thromboembolic complications in patients with FXaI-associated ICH. We performed an individual patient data analysis combining two independent, prospective studies: ANNEXA-4 (180 patients receiving andexanet alfa, NCT02329327) and TICH-NOAC (63 patients receiving tranexamic acid or placebo ± prothrombin complex concentrate, NCT02866838). The primary efficacy outcome was hematoma expansion on follow-up imaging. The primary safety outcome was any thromboembolic complication (ischemic stroke, myocardial infarction, pulmonary embolism, or deep vein thrombosis) at 30 days. We used binary logistic regression models adjusted for baseline hematoma volume, age, calibrated anti-Xa activity, times from last intake of FXaI, and symptom onset to treatment, respectively. Among 243 participants included, the median age was 80 (IQR 75-84) years, baseline hematoma volume was 9.1 (IQR 3.4-21) mL and anti-Xa activity 118 (IQR 78-222) ng/mL. Times from last FXaI intake and symptom onset to treatment were 11 (IQR 7-16) and 4.7 (IQR 3.0-7.6) h, respectively. Overall, 50 patients (22%) experienced hematoma expansion (ANNEXA-4: n=24 (14%); TICH-NOAC: n=26 (41%)). After adjusting for pre-specified confounders (baseline hematoma volume, age, calibrated anti-Xa activity, times from last intake of FXaI, and symptom onset to treatment, respectively), treatment with andexanet alfa was independently associated with decreased odds for hematoma expansion (aOR 0.33, 95% CI 0.13-0.80, p = 0.015). Overall, 26 patients (11%) had any thromboembolic complication within 30 days (ANNEXA-4: n=20 (11%); TICH-NOAC: n=6 (10%)). There was no association between any thromboembolic complication and treatment with andexanet alfa (aOR 0.70, 95% CI 0.16-3.12, p = 0.641). The use of andexanet alfa compared to any other non-specific treatment strategy was associated with decreased odds for hematoma expansion, without increased odds for thromboembolic complications.

Algorithm for Rapid Exclusion of Clinically Relevant Plasma Levels of Direct Oral Anticoagulants in Patients Using the DOAC Dipstick: An Expert Consensus Paper.

With the widespread use of direct oral anticoagulants (DOACs), there is an urgent need for a rapid assay to exclude clinically relevant plasma levels. Accurate and rapid determination of DOAC levels would guide medical decision-making to (1) determine the potential contribution of the DOAC to spontaneous or trauma-induced hemorrhage; (2) identify appropriate candidates for reversal, or (3) optimize the timing of urgent surgery or intervention. The DOAC Dipstick test uses a disposable strip to identify factor Xa- or thrombin inhibitors in a urine sample. Based on the results of a systematic literature search followed by an analysis of a simple pooling of five retrieved clinical studies, the test strip has a high sensitivity and an acceptably high negative predictive value when compared with levels measured with liquid chromatography tandem mass spectrometry or calibrated chromogenic assays to reliably exclude plasma DOAC concentrations ≥30 ng/mL. Based on these data, a simple algorithm is proposed to enhance medical decision-making in acute care indications useful primarily in hospitals not having readily available quantitative tests and 24/7. This algorithm not only determines DOAC exposure but also differentiates between factor Xa and thrombin inhibitors to better guide clinical management.

Andexanet Alfa for the Reversal of Factor Xa Inhibitor Activity: Prespecified Subgroup Analysis of the ANNEXA-4 Study in Japan.

Andexanet alfa, a specific antidote to factor Xa (FXa) inhibitors, has been approved for clinical use in several countries, including Japan, based on the results from the phase 3 trial ANNEXA-4. We aimed to assess the efficacy and safety of andexanet alfa treatment in FXa inhibitor-related acute major bleeding in patients enrolled for ANNEXA-4 in Japan. This prespecified analysis included patients enrolled at Japanese sites in the prospective, open-label, single-arm ANNEXA-4 trial. Eligible patients had major bleeding within 18 hours of oral FXa inhibitor administration. The coprimary efficacy endpoints were percent change in anti-FXa activity and proportion of patients achieving excellent or good hemostatic efficacy 12 hours post-treatment. A total of 19 patients were enrolled, all of whom had intracranial hemorrhage; 16 patients were evaluable for efficacy. Median percent reduction in anti-FXa activity from baseline to nadir was 95.4% in patients taking apixaban, 96.1% in patients taking rivaroxaban, and 82.2% in patients taking edoxaban. Overall, 14/16 patients (88%) achieved excellent or good hemostasis (apixaban, 5/5; rivaroxaban, 6/7; edoxaban, 3/4). Within 30 days, treatment-related adverse events (AEs) and serious AEs occurred in 2 and 5 patients, respectively. One patient died during follow-up, and 2 patients experienced thrombotic events. Treatment with andexanet alfa rapidly reduced anti-FXa activity with favorable hemostatic efficacy in Japanese patients with acute major bleeding. Serious AEs of thrombotic events during rapid reversal of anti-FXa activity arose as particular safety concerns in this population as with previous studies.

Factor Xa inhibitors versus warfarin in severely obese patients with venous thromboembolism or atrial fibrillation

Objectives: Clinical data for the safety and efficacy of Factor Xa (FXa) inhibitors in severely obese patients is limited. Additional information is needed to assess the risks and benefits of using FXa inhibitors in this patient population. Materials and Methods: A single-center and retrospective chart review was conducted in severely obese patients (body mass index [BMI] &gt;40 kg/m2 or weight &gt;120 kg), who received rivaroxaban, apixaban or warfarin for venous thromboembolism (VTE) treatment or prevention of stroke and systemic embolism in non-valvular atrial fibrillation (AF). The primary endpoint was treatment failure, defined as recurrent VTE in VTE treatment or stroke, transient ischemic attack or systemic embolism in AF within one year of anticoagulation initiation. Secondary endpoints included a composite of major bleeding rates and clinically relevant non-major bleeding (CRNMB) rates. Results: Seventy-three patients were included in the final analysis consisting of 43 patients in the FXa inhibitor arm (apixaban [n = 33] and rivaroxaban [n = 10]) and 30 patients in the warfarin arm. The rate of treatment failure was similar between the FXa inhibitor and warfarin groups (4.7% vs. 6.7%; P = 0.814). Although not statistically significant, major bleeding and CRNMB occurred less frequently in patients receiving FXa inhibitors compared to warfarin (9.3% vs. 23.3%; P = 0.182). Subgroup analysis in patients with BMI &gt;50 kg/m2 or weight &gt;150 kg demonstrated similar efficacy and safety outcomes. The use of non-recommended dosing was more common in the apixaban group compared to the rivaroxaban group. Conclusion: FXa inhibitors (apixaban and rivaroxaban) appear to have similar efficacy and safety compared to warfarin in severely obese patients. Larger prospective studies are needed to confirm these results.

Safety and efficacy of apixaban vs. enoxaparin in thromboprophylaxis after spinal stenosis and degenerative spine surgery

IntroductionDegenerative spine surgeries often require postoperative immobilization or reduced mobility, predisposing patients to the formation of thrombosis and higher risk of thromboembolic complications. Despite the significance of this issue, there remains a lack of consensus on the optimal anticoagulant agent for postoperative thromboprophylaxis in spinal stenosis and degenerative spine surgeries. Low molecular weight heparins and direct Xa inhibitors represent two anticoagulant groups with high chemoprophylactic potential. MethodsThis study included a prospective cohort of patients undergoing posterior decompressive surgery with or without instrumentation for degenerative spine disease and/or spinal stenosis. Patients receiving postoperative prophylactic Enoxaparin and Apixaban were selected to evaluate the rate of complications, as assessed by Clavien-Dindo classification, thromboembolic events, and 30-day mortality, readmission, and reoperation rate between the two anticoagulants. Results130 patients were included in the analysis. 65 patients received Apixaban and Enoxaparin in each group. Mean age of the participants was 57.6±11.0. 83.1% underwent laminectomy and posterior spinal fusion, while 22 patients underwent decompressive surgery only. The incidence of venous thromboembolism (P-value=0.403), deep vein thrombosis (p-value=0.999), hematoma formation (p-value=0.403), surgical site infection (p-value=0.901), readmission (p-value=0.545), reoperation (p=0.510), mortality (p=0.648), and complications rate (p-value=0.232) were not statistically different between Enoxaparin and Apixaban. DiscussionBoth Apixaban and Enoxaparin may be viable options for postoperative thromboprophylaxis in spine surgeries with comparable efficacy and safety profile. Future research endeavors should investigate the efficacy of these agents in comparison to placebo in a randomized setting.