Comparative effectiveness of factor Xa non-vitamin K antagonist oral anticoagulants versus phenprocoumon in patients with non-valvular atrial fibrillation.

BACKGROUND: Non-vitamin K antagonist oral anticoagulants (NOACs) have largely supplanted vitamin K antagonists (VKAs) for oral anticoagulation in non-valvular atrial fibrillation (NVAF). However, data on the real-world effectiveness of NOACs vs. phenprocoumon, a VKA widely used in Germany, are limited. The RELOADED study aimed to compare effectiveness of factor Xa NOACs and phenprocoumon in NVAF in clinical practice. METHODS: Patients who started on a factor Xa NOAC or phenprocoumon for NVAF during the study period were enrolled from the Institute for Applied Healthcare Research Berlin. Patients were followed from first prescription until the end of exposure or available data. Primary outcomes were analyzed by Cox proportional hazard regression models and included ischemic stroke and systemic embolism for effectiveness, and intracranial hemorrhage (ICH) for safety. Subgroups of interest were patients with diabetes and patients with renal impairment. RESULTS: The total study population was 64,920; 36.3% of patients initiated phenprocoumon, 34.4% initiated rivaroxaban, 25.0% apixaban, and 4.4% edoxaban. Treatment with phenprocoumon is associated with a similar risk of ischemic stroke/systemic embolism as treatment with rivaroxaban or apixaban; while rivaroxaban (adjusted hazard ratio [HR] 0.57, 95% confidence interval [CI] 0.43-0.75) and apixaban (adjusted HR 0.43, 95% CI 0.31-0.6) were associated with a lower risk of ICH compared to phenprocoumon in NVAF patients. The use of rivaroxaban and apixaban was associated with a lower risk of developing kidney failure in patients with diabetes or renal impairment in comparison to those treated with phenprocoumon. CONCLUSION: The factor Xa NOACs rivaroxaban and apixaban demonstrated similar effectiveness and lower rates of ICH compared with phenprocoumon in this study.

Use of Andexanet Alfa for Factor Xa Inhibitor Reversal in US Verified Trauma Centers: A National Survey.

Direct oral factor Xa inhibitors are replacing vitamin K-dependent antagonists as anticoagulation treatment in many clinical scenarios. Trauma centers are noting an increase in patients presenting on these medications. The 2018 Food and Drug Administration approval of andexanet alfa provides an alternative anticoagulation reversal. Barriers may limit utilization of new medications including a lack of grade 1A evidence supporting the use of prothrombin complex concentrate (PCC) versus andexanet alfa and cost. To evaluate barriers of andexanet alfa utilization by trauma surgeons, a 15-question survey was conducted. There was a 9% completion rate (n = 89). The results revealed 23.5% would choose andexanet alfa as first-line treatment in children, and 25.8% as first-line treatment in adults. The majority of respondents, 64.7% and 67.4%, would use PCC preferentially in children and adults, respectively. Respondents indicated that cost burden was an overriding factor (76.3%); 42.4% cited lack of high-level efficacy data of andexanet alfa for reversal of factor Xa inhibitors. Additional double-blinded multi-institutional randomized controlled trials comparing 4F-PCC and andexanet alfa for factor Xa inhibitor reversal are needed to support efficacy especially with the increased cost associated.

Andexanet Alfa: What We Have Learned from Clinical Trials and Real-World Data.

Andexanet alfa is a specific reversal agent for factor Xa inhibitors with immediate reversal of their anticoagulant effect. Andexanet alfa is currently approved for use in patients treated with rivaroxaban and apixaban who have life-threatening or uncontrolled bleeding. New data from both controlled clinical trials and real-world experience are continuously being published, providing greater insight into the clinical characteristics of the drug, such as efficacy and safety. It is worth considering that andexanet alfa could be of benefit in a variety of different clinical scenarios where patients receiving treatment with apixaban and rivaroxaban (and endoxaban) have life-threatening conditions. These different clinical scenarios, which range from pre-treatment of urgent surgery, especially neurosurgical interventions, and concomitant use of andexanet alfa and prothrombin complex concentrate to onset of bleeding more than 6 h prior to admission, should be clarified as well as the issue of "low/high" dose of andexanet alfa and the need for baseline anti-Xa inhibitor levels measured by point-of-care testing. Finally, management of patients at high risk of thrombosis or recent arterial/venous thrombotic events needs to be further explored. In this current opinion, we address these urgent questions in the light of recent literature and clinical trial data.

The use of andexanet alpha in the Polish setting: An interdisciplinary protocol. Expert consensus statement of the Polish Cardiac Society.

Andexanet alfa (AA) is a recombinant inactive analog of human activated factor X (FXa), effectively reversing the effects of its inhibitors - rivaroxaban and apixaban, which are available in Poland. The drug was approved for clinical use registration after the publication of the results of the ANNEXA-4 trial (Andexanet Alfa, a Novel Antidote to the Anticoagulation Effects of FXa Inhibitors 4), in which its efficacy in restoring hemostasis in life-threatening hemorrhages in patients receiving using the aforementioned anticoagulants was demonstrated. Hence, AA is now recommended for patients on apixaban or rivaroxaban therapy with massive and uncontrollable hemorrhages, including hemorrhagic strokes (HS) and gastrointestinal bleeding. Drug-specific chromogenic anti-Xa assays are generally best suited for estimating rivaroxaban and apixaban plasma levels, aside from direct assessment of their concentrations. The absence of anti-Xa activity, determined using these assays, allows us to rule out the presence of clinically relevant plasma concentrations of any FXa inhibitor. On the other hand, the dose of AA should not be modified based on the results of coagulation tests, as it depends solely on the time that elapsed since the last dose of FXa inhibitor and oon the dose and type of FXa inhibitor. AA is administered as an intravenous (i.v.) bolus, followed by an i.v. infusion of the drug. The maximum reversal of anti-Xa activity occurs within two minutes of the end of the bolus treatment, with the continuation of the continuous i.v. infusion allowing the effect to be maintained for up to two hours afterwards. Because anticoagulant activity can reappear after the infusion is completed, it is currently unclear at what point after AA administration FXa inhibitors or heparin should be re-administered. In Poland AA is starting to become available and its urgent need to administer it to patients with severe bleeding on apixaban or rivaroxaban.

Four-factor prothrombin complex concentrate versus andexanet alfa for the reversal of traumatic brain injuries.

BACKGROUND: Andexanet alfa was approved in 2018 for reversal of direct oral anticoagulants but due to issues of cost and access, four-factor prothrombin complex concentrate (4F-PCC) continues to be used for this indication. The objective of this study is to evaluate outcomes of reversal with these agents in patients with isolated traumatic brain injuries (TBI). METHODS: This is a retrospective review of 35 trauma centres from 2014 to 2021. Patients were included with an Abbreviated Injury Scale (AIS)>2 for head and having received andexanet alfa or 4F-PCC within 24 hours of admission. Patients were excluded if P2Y12 inhibitor use or AIS>2 outside of head. Primary outcome includes rate of mortality/hospice at hospital discharge. Secondary outcomes include a composite of serious hospital complications. A subgroup analysis of severe TBI patients (AIS head 4 or 5) was completed. Multivariable logistic regression was used to account for differences in comorbidities and TBI severity. RESULTS: 4F-PCC was given to 265 patients with another 59 receiving andexanet alfa. Patients in the andexanet alfa group were more likely to have an AIS head score of 5 (47.5% vs 26.1%; p<0.005). After adjusting for severity of TBI and comorbidities with regard to tomortality/hospice, there were 15 (25.4%) patients in the andexanet alfa group and 49 (18.5%) in the 4F-PCC group (OR 1.34; 95% CI 0.67 to 2.71). This remained consistent when looking at severe patients with TBI with 12 (28.6%) andexanet alfa patients and 37 (28.7%) 4F-PCC patients (OR 0.93 (95% CI 0.40 to 2.16)). Severe hospital complications were also similar between groups with 5 (8.5%) andexanet alfa patients as compared with 21 (7.9%) 4F-PCC patients (OR 1.01; 95% CI 0.36 to 2.88). CONCLUSION: There was no firm conclusion on the treatment effect in mortality/hospice or serious complications among isolated TBI patients reversed with 4F-PCC as compared with andexanet alfa.

Comparative analysis of andexanet alfa and prothrombin complex concentrate in reversing anticoagulation by rivaroxaban ex vivo.

BACKGROUND: The comparative effectiveness of the specific antidote andexanet alfa vs the nonspecific therapy four-factor prothrombin complex concentrates (4F-PCCs) as reversal agents for direct factor Xa (FXa) inhibitors in severely bleeding patients is unclear. We hypothesised that specific reversal using andexanet alfa would be more effective than a high dose of PCC (50 IU kg-1) for reversing the FXa inhibitor rivaroxaban. METHODS: The reversal potential of andexanet alfa, various 4F-PCCs, and activated PCC was investigated ex vivo in human blood anticoagulated with rivaroxaban (37.5, 75, 150, and 300 ng ml-1) using a panel of coagulation parameters, including conventional coagulation assays, thrombin generation, and a newly developed viscoelastometric device. We simulated in vivo conditions of coagulation activation and fibrin formation using flow chamber experiments of thrombogenicity potential under arterial flow conditions. RESULTS: The 4F-PCCs normalised clotting profiles only at low rivaroxaban concentrations, whereas andexanet alfa and activated PCC significantly shortened clotting time at all rivaroxaban concentrations. Only andexanet alfa restored thrombin generation to baseline. Flow chamber results showed that various 4F-PCCs concentration-dependently restored clot formation. CONCLUSIONS: In contrast to thrombin generation measurements, haemostatic reversal of rivaroxaban using high-dose 4F-PCCs exhibited similar efficacy as andexanet alfa in flow chamber experiments. The haemostatic effects of 4F-PCCs and andexanet alfa in the context of bleeding patients taking FXa inhibitors requires further study.

Characterization of an andexanet alfa administration protocol guided by drug-specific quantitative anti-Xa assays.

Following FDA approval in 2018, consensus guidelines recommend andexanet alfa as first-line therapy for the management of life-threatening or uncontrollable bleeding in patients taking oral factor Xa (FXa) inhibitors. Dosing is based on the specific FXa inhibitor and dose, and the time elapsed since the patient's last administration of the medication. Additionally, at our institution, anti-FXa screens and drug-specific assays are obtained to guide subsequent dosing based on institution protocol. The objective of this study was to evaluate andexanet alfa utilization based on anti-Xa and FXa-inhibitor-specific assays and assess associated outcomes. This was a retrospective, single-center study aimed to describe the use of anti-FXa and specific direct oral anticoagulant assays to guide the utilization and administration of andexanet alfa. Secondary endpoints evaluated included thrombotic events during index hospitalization, hospital length of stay, hospital mortality, and discharge disposition. Overall, most patients were prescribed apixaban for atrial fibrillation and received andexanet alfa for reversal of intracranial hemorrhage in the emergency department. In general, DOAC-specific assays were concordant with last known times; however, there appears to be minimal correlation with DOAC-specific assay levels and survival. There were 9 thrombotic events (8.7%) in 8 patients. In this cohort, collection of an anti-FXa assay screen was a practical strategy to guide reversal with andexanet alfa; however, the addition of DOAC-specific assay levels may not enhance clinical utility.

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

AIMS: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Dose-Related Effectiveness of Andexanet Alfa for Reversal of Apixaban Anticoagulation in a Porcine Polytrauma Model.

BACKGROUND: Andexanet alfa (andexanet) is a reversal agent for use in patients with life-threatening or uncontrolled bleeding treated with oral factor Xa (FXa) inhibitors. There are limited data on the dose-response relationship of andexanet and FXa inhibitor-related bleeding. OBJECTIVE: The aim of this study was to assess the dose-related effectiveness of andexanet in reducing blood loss, improving survival, and reversing apixaban anticoagulation in a porcine polytrauma model. METHODS: Apixaban was given orally to 40 male pigs for 3 days at a dose of 20 mg/d. On day 3, following bilateral femur fractures and blunt liver injury, animals (n = 8/group) received andexanet (250-mg bolus, 250-mg bolus + 300-mg 2-hour infusion, 500-mg bolus, or 500-mg bolus + 600-mg 2-hour infusion) or vehicle (control). Total blood loss was the primary endpoint. Coagulation parameters were assessed for 300 minutes or until death. Data were analyzed with a mixed-model analysis of variance. RESULTS: Administration of 250-mg bolus + 300-mg infusion, andexanet 500-mg bolus, and 500-mg bolus + 600-mg infusion significantly decreased total blood loss by 37, 58, and 61%, respectively (all p < 0.0001), with 100% survival. Andexanet 250-mg bolus was ineffective in reducing total blood loss (6%) and mortality (63% survival) versus controls. Andexanet 500-mg bolus ± infusion neutralized anti-FXa activity to less than 50 ng/mL. Andexanet neutralization of thrombin generation and thromboelastometry parameters was dose and infusion time dependent. CONCLUSION: In a porcine polytrauma model with major bleeding on apixaban, andexanet dose dependently decreased anti-FXa activity. Lower anti-FXa levels (<50 ng/mL) with andexanet 500-mg bolus ± infusion were correlated with 60% less blood loss and 100% survival versus controls.

Decrease of prothrombin level during thrombolysis in acute myocardium infarction.

Previously, the direct interactions of Bß26-42 fibrin residues with prothrombin were demonstrated. It was also shown that forming prothrombin complexes with E- or DDE-fragments causes non-enzymatic prothrombin activation. The direct measuring of the prothrombin level in the blood plasma of patients with acute myocardial infarction (AMI) allowed us to find a situation where such an activation can occur in vivo. Blood coagulation parameters in the blood plasma of patients with AMI were measured at 2 hours, three days, and seven days after the thrombolysis by streptokinase accompanied with intravenous administration of anticoagulants: unfractionated high molecular weight heparin (HMWH) and low-molecular-weight heparin (LMWH). The prothrombin level in the blood plasma of patients with AMI was normal before thrombolytic therapy and substantially decreased after streptokinase administration. This effect was prominent in the case of concomitant anticoagulant therapy with LMWH and was not observed when HMWH was applied. It can be explained by the fact that LMWH preferentially inhibits factor Xa, while the HMWH is an effective inhibitor of both factor Xa and thrombin. This observation suggested that the prothrombin level decrease was caused by the thrombin-like activity and possible autolysis of prothrombin by thrombin. Also, thrombolytic therapy with streptokinase caused the accumulation of fibrin degradation products (FDPs), some of which were able to bind prothrombin. The dramatic decrease of prothrombin level in the blood plasma of patients with AMI during thrombolysis allowed us to conclude the non-enzymatic prothrombin activation with the following autolysis of prothrombin that contributes to the pathology.

Administration of andexanet alfa for traumatic intracranial hemorrhage in the setting of massive apixaban overdose: A case report.

PURPOSE: Apixaban is a direct-acting oral anticoagulant that selectively inhibits factor Xa. Reversal strategies utilized to treat factor Xa inhibitor-associated bleeding include andexanet alfa, prothrombin complex -concentrate (PCC), and activated PCC (aPCC). The optimal treatment of traumatic intracranial hemorrhage in the setting of an apixaban overdose is unknown. SUMMARY: This case report describes a 69-year-old female who initially presented to an emergency department at a community hospital due to a ground-level fall with traumatic intracranial hemorrhage. The patient reportedly ingested apixaban 275 mg, carvedilol 250 mg, atorvastatin 1,200 mg, and unknown amounts of amlodipine and ethanol. Anti-inhibitor coagulant complex, an aPCC, was administered approximately 3 hours after presentation. Initial thromboelastography performed approximately 4 hours after presentation showed a prolonged reaction time of 16.8 minutes. Ongoing imaging and evidence of coagulopathy prompted repeated aPCC administration to a cumulative dose of approximately 100 U/kg. The patient underwent craniotomy with hematoma evacuation. Postoperative imaging showed expansion of the existing intracranial hemorrhage and new areas of hemorrhage. Andexanet alfa was administered approximately 18 hours after presentation, followed by repeat craniotomy with evacuation of the hematoma. No further expansion of the intracranial hemorrhage was observed, and the reaction time on thromboelastography was normalized at 6.3 minutes. CONCLUSION: This case suggests that andexanet alfa may have a role in the management of traumatic hemorrhage in the setting of an acute massive apixaban overdose. Use of andexanet alfa, PCC, and aPCC in this context requires further research.

Recommendations for the use of andexanet alfa in the management of bleeding in patients on oral factor Xa inhibitors in Switzerland: Guideline from the Working Party Hemostasis of the Swiss Society of Hematology

Anticoagulants are essential in preventing and treating thrombosis. Unfortunately, their use is accompanied by an enhanced risk of bleeding. Since the introduction of direct oral anticoagulants (DOACs), the risk of major bleeding has been reduced but not eliminated. Major bleeding events related to the use of factor Xa inhibitors can be challenging to manage. In recent years, four-factor prothrombin complex concentrates have been used in patients with severe bleeding taking oral direct factor Xa inhibitors (apixaban, edoxaban and rivaroxaban). Andexanet alfa (OndexxyaTM, AstraZeneca AG) is a specially designed recombinant version of human factor Xa that acts as a decoy receptor to reverse the effects of factor Xa inhibitors. Since 2 December 2020, andexanet alfa has been used in Switzerland for adult patients receiving apixaban or rivaroxaban when reversal of anticoagulation is required because of life-threatening or uncontrolled bleeding. However, the use of andexanet alfa remains a challenge owing to its cost, the reported thrombotic complications and the fact that its efficacy mainly relates to intracranial haemorrhage. Moreover, the use of nonspecific reversal agents together with andexanet alfa is controversial. The present recommendations on the use of andexanet alfa in the management of bleeding in patients on factor Xa inhibitors in Switzerland were developed by a group of Swiss experts from the Working Party Hemostasis of the Swiss Society of Hematology. These recommendations aim to provide support to clinicians in their decision-making in the management of patients with major bleeding receiving factor Xa inhibitors.

Hemostatic efficacy of four factor prothrombin complex concentrate in intracerebral hemorrhage patients receiving warfarin vs. factor Xa inhibitors.

INTRODUCTION: 4-F PCC is administered for reversal of factor Xa inhibitor-associated coagulopathy despite a lack of quality evidence demonstrating hemostatic efficacy. The aim of this study was to evaluate the hemostatic efficacy of 4-F PCC in intracerebral hemorrhage patients who received factor Xa inhibitors versus warfarin. MATERIALS AND METHODS: This was a multi-center, retrospective, observational cohort study at a large healthcare system. Patients taking warfarin received 4-F PCC 25-50 units/kg based on the presenting INR, while patients taking a factor Xa inhibitor received 35 units/kg. The primary outcome was the percentage of patients with good or excellent hemostatic efficacy as assessed by modified Sarode scale, with neurologic outcomes assessed as a secondary endpoint. Patients were included in the primary outcome population if they had a repeat CT scan within 24 h. RESULTS: One hundred fifty-seven patients were included in the primary outcome population; [warfarin (n = 76), factor Xa inhibitors (n = 81)]. Hemostatic efficacy was 83 % in the warfarin group versus 75 % in the factor Xa inhibitor group (p = 0.24). The hemostatic efficacy risk difference between the groups was 7.6 % (95 % CI 5.1 %, 20.2 %). Good neurologic outcome (mRS 0-2) at discharge was 17 % in warfarin patients versus 12 % in the factor Xa inhibitor patients (p = 0.40). CONCLUSIONS: There was no significant difference in hemostatic efficacy or clinical outcomes between patients taking warfarin or a factor Xa inhibitor following reversal with 4-F PCC. This study provides further support that 4-F PCC can be used for the reversal of factor Xa inhibitor-associated coagulopathy.

A hybrid automated event adjudication system for clinical trials.

INTRODUCTION: In clinical trials, event adjudication is a process to review and confirm the accuracy of outcomes reported by site investigators. Despite efforts to automate the communication between a clinical-data-and-coordination center and an event adjudication committee, the review and confirmation of outcomes, as the core function of the process, still fully rely on human labor. To address this issue, we present an automated event adjudication system and its application in two randomized controlled trials. METHODS: Centrally executed by a clinical-data-and-coordination center, the automated event adjudication system automatedly assessed and classified outcomes in a clinical data management system. By checking clinically predefined criteria, the automated event adjudication system either confirmed or unconfirmed an outcome and automatedly updated its status in the database. It also served as a management tool to assist staff to oversee the process of event adjudication. The system has been applied in: (1) the Cardiovascular Outcomes for People Using Anticoagulation Strategies (COMPASS) trial and (2) the New Approach riVaroxaban Inhibition of Factor Xa in a Global trial versus Aspirin to prevenT Embolism in Embolic Stroke of Undetermined Source (NAVIGATE ESUS) trial. The automated event adjudication system first screened outcomes reported on a case report form and confirmed those with data matched to preset definitions. For selected primary efficacy, secondary, and safety outcomes, the unconfirmed cases were referred to a human event adjudication committee for a final decision. In the New Approach riVaroxaban Inhibition of Factor Xa in a Global trial versus Aspirin to prevenT Embolism in Embolic Stroke of Undetermined Source (NAVIGATE ESUS) trial, human adjudicators were given priority to review cases, while the automated event adjudication system took the lead in the Cardiovascular Outcomes for People Using Anticoagulation Strategies (COMPASS) trial. RESULTS: Outcomes that were adjudicated in a hybrid model are discussed here. The COMPASS automated event adjudication system adjudicated 3283 primary efficacy outcomes and confirmed 1652 (50.3%): 132 (21.1%) strokes, 522 (53%) myocardial infarctions, and 998 (59.7%) causes of deaths. The NAVIGATE ESUS one adjudicated 737 cases of selected outcomes and confirmed 383 (52%): 219 (51.5%) strokes, 34 (42.5%) myocardial infarctions, 73 (54.9%) causes of deaths, and 57 (57.6%) major bleedings. After one deducts the time needed for migrating the system to a new study, the automated event adjudication system helped to reduce the time required for human review from approximately 1303 to 716.5 h for the Cardiovascular Outcomes for People Using Anticoagulation Strategies trial and from 387 to 196 h for the New Approach riVaroxaban Inhibition of Factor Xa in a Global trial versus Aspirin to prevenT Embolism in Embolic Stroke of Undetermined Source trial. CONCLUSION: The automated event adjudication system in combination with human adjudicators provides a streamlined and efficient approach to event adjudication in clinical trials. To immediately apply automated event adjudication, one can first consider the automated event adjudication system and involve human assistance for cases unconfirmed by the former.

Final Study Report of Andexanet Alfa for Major Bleeding With Factor Xa Inhibitors.

BACKGROUND: Andexanet alfa is a modified recombinant inactive factor Xa (FXa) designed to reverse FXa inhibitors. ANNEXA-4 (Andexanet Alfa, a Novel Antidote to the Anticoagulation Effects of Factor Xa Inhibitors) was a multicenter, prospective, phase-3b/4, single-group cohort study that evaluated andexanet alfa in patients with acute major bleeding. The results of the final analyses are presented. METHODS: Patients with acute major bleeding within 18 hours of FXa inhibitor administration were enrolled. Co-primary end points were anti-FXa activity change from baseline during andexanet alfa treatment and excellent or good hemostatic efficacy, defined by a scale used in previous reversal studies, at 12 hours. The efficacy population included patients with baseline anti-FXa activity levels above predefined thresholds (≥75 ng/mL for apixaban and rivaroxaban, ≥40 ng/mL for edoxaban, and ≥0.25 IU/mL for enoxaparin; reported in the same units used for calibrators) who were adjudicated as meeting major bleeding criteria (modified International Society on Thrombosis and Haemostasis definition). The safety population included all patients. Major bleeding criteria, hemostatic efficacy, thrombotic events (stratified by occurring before or after restart of either prophylactic [ie, a lower dose, for prevention rather than treatment] or full-dose oral anticoagulation), and deaths were assessed by an independent adjudication committee. Median endogenous thrombin potential at baseline and across the follow-up period was a secondary outcome. RESULTS: There were 479 patients enrolled (mean age, 78 years; 54% male; 86% White); 81% were anticoagulated for atrial fibrillation, and the median time was 11.4 hours since last dose, with 245 (51%) on apixaban, 176 (37%) on rivaroxaban, 36 (8%) on edoxaban, and 22 (5%) on enoxaparin. Bleeding was predominantly intracranial (n=331 [69%]) or gastrointestinal (n=109 [23%]). In evaluable apixaban patients (n=172), median anti-FXa activity decreased from 146.9 ng/mL to 10.0 ng/mL (reduction, 93% [95% CI, 94-93]); in rivaroxaban patients (n=132), it decreased from 214.6 ng/mL to 10.8 ng/mL (94% [95% CI, 95-93]); in edoxaban patients (n=28), it decreased from 121.1 ng/mL to 24.4 ng/mL (71% [95% CI, 82-65); and in enoxaparin patients (n=17), it decreased from 0.48 IU/mL to 0.11 IU/mL (75% [95% CI, 79-67]). Excellent or good hemostasis occurred in 274 of 342 evaluable patients (80% [95% CI, 75-84]). In the safety population, thrombotic events occurred in 50 (10%) patients; in 16 patients, these occurred during treatment with prophylactic anticoagulation that began after the bleeding event. No thrombotic episodes occurred after oral anticoagulation restart. Specific to certain populations, reduction of anti-FXa activity from baseline to nadir significantly predicted hemostatic efficacy in patients with intracranial hemorrhage (area under the receiver operating characteristic curve, 0.62 [95% CI, 0.54-0.70]) and correlated with lower mortality in patients <75 years of age (adjusted P=0.022; unadjusted P=0.003). Median endogenous thrombin potential was within the normal range by the end of andexanet alfa bolus through 24 hours for all FXa inhibitors. CONCLUSIONS: In patients with major bleeding associated with the use of FXa inhibitors, treatment with andexanet alfa reduced anti-FXa activity and was associated with good or excellent hemostatic efficacy in 80% of patients. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02329327.

Application of anti-Xa assay in monitoring unfractionated heparin therapy in contemporary antithrombotic management.

INTRODUCTION: Unfractionated heparin remains the most widely used agent in the prevention and acute treatment of thrombosis. Pharmacological complexities of this intriguing agent mandate frequent monitoring of its anticoagulant properties to maintain safe and effective hematological outcomes. Although activated partial thromboplastin time has been the standard test to monitor unfractionated heparin therapy for many decades, the anti-Xa assay has emerged as a substitute or adjunct in many institutions. AREAS COVERED: This brief report outlines the key features of anti-Xa assay in monitoring unfractionated heparin in acute management of thrombosis in various contemporary settings, with emphasis on evidence for clinical outcomes. PubMed.gov database was utilized to obtain the pertinent literature. EXPERT OPINION: The anti-Xa activity is primarily a reflection of UFH concentration and does not account for other hematological variables frequently present in contemporary anticoagulation management. The advantage of the anti-Xa assay in monitoring UFH therapy is predicated upon its limitations to account for global physiological hemostasis. There are significant disease and drug interactions that may potentially result in false in-vitro analysis of anti-Xa activity. Routine application of the anti-Xa assay is not evidence-based at this time.

Case Report: Extended Duration Andexanet Alfa Infusion in a Surgical Trauma Patient.

Background: Andexanet alfa (andexanet) is the only FDA-approved medication for reversal of apixaban and rivaroxaban anticoagulation for life-threatening or uncontrolled bleeding. Infusion modifications may be required in surgical patients undergoing prolonged operative intervention but have not previously been described. Case Report: A 78-year-old woman on rivaroxaban for atrial fibrillation was admitted to the trauma service for a mechanical fall, sustaining a T4 burst fracture with severe canal stenosis and spinal cord edema resulting in loss of strength and sensation in her legs. Clinically relevant rivaroxaban activity was verified with an elevated low molecular weight heparin anti-factor Xa assay, and laboratory confirmed coagulopathy was demonstrated by a prolonged prothrombin time, thromboelastography (TEG) R-time, and activated clotting time (ACT). The patient required urgent surgical intervention for spinal fixation. Given the expected prolonged duration of the procedure, standard dose andexanet was initiated with a prolonged infusion at half the standard rate during the operation. The procedure was successful and intraoperative TEGs demonstrated normalization of R-time and ACT throughout the procedure. The patient did not experience any complications postoperatively and successfully discharged to inpatient rehabilitation. Conclusion: Modifications to the andexanet infusion may be required in surgical patients requiring rivaroxaban reversal for a prolonged procedure. Further data are needed to determine the optimal approach to infusion modification.

The use of andexanet alfa and 4-factor prothrombin complex concentrate in intracranial hemorrhage.

OBJECTIVE: to describe the clinical and safety outcomes between andexanet alfa (AA) and 4-factor prothrombin complex concentrate (4F-PCC) for the reversal of apixaban or rivaroxaban in the setting of an intracranial hemorrhage (ICH). METHODS: A retrospective, multicentered descriptive study was conducted in hospitalized patients 18 years of age or older from June 2018 to October 2019 who received AA or 4F-PCC for the reversal of apixaban or rivaroxaban in the setting of ICH. Patients were excluded if they had received 4F-PCC prior to AA after its addition to the institution wide formulary. Other exclusion criteria were history or presence of heparin-induced thrombocytopenia or disseminated intravascular coagulation, estimated hematoma volume of >60 mL, Glasgow Coma Scores <7, or no repeat CT head scan. Information was collected from the electronic medical records. The primary outcome was the achievement of excellent or good hemostatic efficacy upon the repeat computer tomography (CT) scan performed after the infusion of study drugs. Secondary outcomes included disposition, survival to hospital discharge, 30-day readmission, length of hospital stay, length of ICU stay, incidence of thromboembolic events. RESULTS: A total of 24 patients were included in the study, of which 9 received AA and 15 received 4F-PCC. The achievement of excellent or good hemostatic efficacy upon repeat CT scan occurred in 7 (77.8%) patients in the AA group and in 14 (93.3%) patients in the 4-F PCC group. All patients in the AA group survived to hospital discharge with no 30-day morality and 86.7% patients in the 4F-PCC group. CONCLUSION: This study suggests that real-world clinical and safety outcomes between andexanet alfa and 4F-PCC for the reversal of factor Xa inhibitors in the setting of ICH are similar to ones reported in clinical trials.

Retrospective review of Andexanet Alfa versus 4-Factor Prothrombin Complex Concentrate for reversal of DOAC-Associated Intracranial Hemorrhage.

Background: Mortality of oral anticoagulation-associated ICH is around 60%, with oral anticoagulation increasing the risk of ICH seven to ten-fold compared to no anticoagulation. Current guidelines recommend DOACs (direct oral anticoagulants) as first-line therapy in the treatment of VTE (Venous Thromboembolism) due to their more favorable safety profile. There are two agents available for DOAC reversal, Coagulation Factor Xa (recombinant), inactivated-zhzo (andexanet alfa, Andexxa®) and 4-factor prothrombin complex concentrate (4FPCC). There is little data comparing the two agents in real-life clinical settings. OBJECTIVE: The primary objective of this study was to determine if there was a difference in hemostatic efficacy of andexanet alfa and 4FPCC in patients with a factor Xa inhibitor-related intracranial hemorrhage. METHODS: This was a retrospective, single-center study conducted in adult patients admitted at a quaternary academic medical center from September 2017 to March 2021. Adults with a diagnosis of intracranial hemorrhage (ICH) were included if they received either 4FPCC or andexanet alfa for reversal of apixaban or rivaroxaban. In addition to hemostatic efficacy per imaging, we assessed disposition location, cerebral performance score, blood product consumption, and the development of a new thrombus. RESULTS: A total of 46 patients were included in this study, 15 received 4FPCC (32%) and 31 received andexanet alfa (68%). There was no difference in the proportion of patients with excellent (4FPCC 9 [60%] vs. andexanet alfa 16 [51.6%], p = 0.61), good (4FPCC 2 [13.3%] vs. andexanet alfa 7 [22.6%]), or poor (4FPCC 1 [6.7%] vs. andexanet alfa 5 [16.1%]) hemostasis after administration of each agent. There were no significant differences in any secondary outcomes. CONCLUSION AND RELEVANCE: Our study found no difference in hemostatic efficacy between andexanet alfa and 4FPCC. At this time, clinicians should choose an agent based on individual patient presentation and resource availability. Further research will help clarify the role of each agent in the management of DOAC-related intracranial hemorrhage.