Engineering and evaluation of FXa bypassing agents that restore hemostasis following Apixaban associated bleeding.

Direct oral anticoagulants (DOACs) targeting activated factor Xa (FXa) are used to prevent or treat thromboembolic disorders. DOACs reversibly bind to FXa and inhibit its enzymatic activity. However, DOAC treatment carries the risk of anticoagulant-associated bleeding. Currently, only one specific agent, andexanet alfa, is approved to reverse the anticoagulant effects of FXa-targeting DOACs (FXaDOACs) and control life-threatening bleeding. However, because of its mechanism of action, andexanet alfa requires a cumbersome dosing schedule, and its use is associated with the risk of thrombosis. Here, we present the computational design, engineering, and evaluation of FXa-variants that exhibit anticoagulation reversal activity in the presence of FXaDOACs. Our designs demonstrate low DOAC binding affinity, retain FXa-enzymatic activity and reduce the DOAC-associated bleeding by restoring hemostasis in mice treated with apixaban. Importantly, the FXaDOACs reversal agents we designed, unlike andexanet alfa, do not inhibit TFPI, and consequently, may have a safer thrombogenic profile.

Aptameric hirudins as selective and reversible EXosite-ACTive site (EXACT) inhibitors.

Potent and selective inhibition of the structurally homologous proteases of coagulation poses challenges for drug development. Hematophagous organisms frequently accomplish this by fashioning peptide inhibitors combining exosite and active site binding motifs. Inspired by this biological strategy, we create several EXACT inhibitors targeting thrombin and factor Xa de novo by linking EXosite-binding aptamers with small molecule ACTive site inhibitors. The aptamer component within the EXACT inhibitor (1) synergizes with and enhances the potency of small-molecule active site inhibitors by many hundred-fold (2) can redirect an active site inhibitor's selectivity towards a different protease, and (3) enable efficient reversal of inhibition by an antidote that disrupts bivalent binding. One EXACT inhibitor, HD22-7A-DAB, demonstrates extraordinary anticoagulation activity, exhibiting great potential as a potent, rapid onset anticoagulant to support cardiovascular surgeries. Using this generalizable molecular engineering strategy, selective, potent, and rapidly reversible EXACT inhibitors can be created against many enzymes through simple oligonucleotide conjugation for numerous research and therapeutic applications.

Association of anti-factor Xa-guided anticoagulation with hemorrhage during ECMO support: A systematic review and meta-analysis.

BACKGROUND: The use of extracorporeal membrane oxygenation (ECMO) is associated with complex hemostatic changes. Systemic anticoagulation is initiated to prevent clotting in the ECMO system, but this comes with an increased risk of bleeding. Evidence on the use of anti-Xa-guided monitoring to prevent bleeding during ECMO support is limited. Therefore, we aimed to analyze the association between anti-factor Xa-guided anticoagulation and hemorrhage during ECMO. METHODS: A systematic review and meta-analysis was performed (up to August 2023). PROSPERO: CRD42023448888. RESULTS: Twenty-six studies comprising 2293 patients were included in the analysis, with six works being part of the meta-analysis. The mean anti-Xa values did not show a significant difference between patients with and without hemorrhage (standardized mean difference -0.05; 95% confidence interval [CI]: -0.19; 0.28, p = .69). We found a positive correlation between anti-Xa levels and unfractionated heparin dose (UFH; pooled estimate of correlation coefficients 0.44; 95% CI: 0.33; 0.55, p < .001). The most frequent complications were any type of hemorrhage (pooled 36%) and thrombosis (33%). Nearly half of the critically ill patients did not survive to hospital discharge (47%). CONCLUSIONS: The most appropriate tool for anticoagulation monitoring in ECMO patients is uncertain. Our analysis did not reveal a significant difference in anti-Xa levels in patients with and without hemorrhagic events. However, we found a moderate correlation between anti-Xa and the UFH dose, supporting its utilization in monitoring UFH anticoagulation. Given the limitations of time-guided monitoring methods, the role of anti-Xa is promising and further research is warranted.

Physiologically based absorption modeling to predict the bioequivalence of two apixaban formulations.

The equivalence of absorption rates and extents between generic drugs and their reference formulations is crucial for ensuring therapeutic comparability. Bioequivalence (BE) studies are widely utilized and play a pivotal role in substantiating the approval and promotional efforts for generic drugs. Virtual BE simulation is a valuable tool for mitigating risks and guiding clinical BE studies, thereby minimizing redundant in vivo BE assessments. Herein, we successfully developed a physiologically based absorption model for virtual BE simulations, which precisely predicts the BE of the apixaban test and reference formulations. The modeling results confirm that the test and reference formulations were bioequivalent under both fasted and fed conditions, consistent with clinical studies. This highlights the efficacy of physiologically based absorption modeling as a powerful tool for formulation screening and can be adopted as a methodological and risk assessment strategy to detect potential clinical BE risks.

Development of immediate-release formulation with reliable absorption of rivaroxaban in various meal regimes.

The bioavailability of rivaroxaban at the higher doses (15 and 20 mg) is considerably reduced when the drug is administered on an empty stomach. This can lead to inadequate anticoagulant effect, and therefore, it is recommended to use the higher doses at fed state. However, proper posology may represent a barrier for some patients. Therefore, the aim of this study was to evaluate innovative rivaroxaban-containing formulations designed to eliminate the food effect to ensure reliable absorption and thus to improve patient adherence with the treatment. Three prototypes (Cocrystal, HPMCP and Kollidon) with rivaroxaban were developed and their bioavailability and food effect in comparison to the reference product was tested in open label, randomized, single oral dose, crossover studies, where test products were administered under fasting and fed conditions and the reference product was administered under fed conditions. Comparable bioavailability for all tested prototypes both under fed and fasting conditions was demonstrated as the 90% confidence intervals of the geometric mean ratios for area under the concentration-time curve remained within the standard acceptance range of 80.00%-125.00%. An innovative immediate release form of rivaroxaban with no food effect on drug bioavailability has been developed, which may represent an important step toward increasing adherence, improving treatment outcome and reducing health care costs.

A new model of portal vein thrombosis in rats with cirrhosis induced by partial portal vein ligation plus carbon tetrachloride and intervened with rivaroxaban.

BACKGROUND AND AIMS: Portal vein thrombosis (PVT) is a common complication of liver cirrhosis that can aggravate portal hypertension. However, there are features of both PVT and cirrhosis that are not recapitulated in most current animal models. In this study, we aimed to establish a stable animal model of PVT and cirrhosis, intervene with anticoagulant, and explore the related mechanism. METHODS: First, 49 male SD rats received partial portal vein ligation (PPVL), and 44 survival rats were divided into 6 groups: PPVL control group; 4-week, 6 -week, 8-week, and 10-week model group; and the rivaroxaban (RIVA)-treated group. The rats were intoxicated with or without carbon tetrachloride (CCl4) for 4-10 weeks. Seven normal rats were used as the normal controls. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and parameters for blood coagulation were all assayed with kits. Liver inflammation, collagen deposition and hydroxyproline (Hyp) levels were also measured. The extrahepatic macro-PVT was observed via portal vein HE staining, etc. The intrahepatic microthrombi was stained via fibrin immunohistochemistry. The portal blood flow velocity (PBFV) and diameter were detected via color Doppler ultrasound. Vascular endothelial injury was evaluated by von Willebrand Factor (vWF) immunofluorescence. Fibrinolytic activity was estimated by western blot analysis of fibrin and plasminogen activator inhibitor-1 (PAI-1). RESULTS: After PPVL surgery and 10 weeks of CCl4 intoxication, a rat model that exhibited characteristics of both cirrhosis and extra and intrahepatic thrombi was established. In cirrhotic rats with PVT, the PBFV decreased, both factors of pro- and anti-coagulation decreased, but with relative hypercoagulable state, vascular endothelial injured, and fibrinolytic activity decreased. RIVA-treated rats had improved coagulation function, increased PBFV and attenuated thrombi. This effect was related to the improvements in endothelial injury and fibrinolytic activity. CONCLUSIONS: A new rat model of PVT with cirrhosis was established through partial portal vein ligation plus CCl4 intoxication, with the characteristics of macrothrombi at portal veins and microthrombi in hepatic sinusoids, as well as liver cirrhosis. Rivaroxaban could attenuate PVT in cirrhosis in the model rats. The underlying mechanisms of PVT formation in the rat model and pharmacological action of rivaroxaban are related to the regulation of portal blood flow, coagulant factors, and vascular endothelial cell function.

Comparison of Fixed Versus Weight-Based Prothrombin Complex Concentrate Dosing Strategies for Factor Xa Inhibitor Reversal.

Background: Our institution introduced fixed-dose prothrombin complex concentrate (PCC) to streamline order verification and medication administration. Previous studies using fixed-dose PCC for vitamin K antagonist reversal showed comparable efficacy to weight-based dosing. Objective: To compare fixed versus weight-based PCC dosing for reversal of Factor Xa Inhibitor (FXaI) effects. Methods: Retrospective cohort study conducted at a tertiary care academic medical center. Patients who received PCC to reverse the effects of apixaban or rivaroxaban were eligible. Subjects in the fixed-dose group (5000 units or 2000 units) were compared to weight-based PCC (50 units/kg). The primary outcome was time between order entry and medication administration. Secondary outcomes included: average PCC dose, postadministration procedures, achieved hemostasis, 30-day mortality, hospital length of stay, and adverse drug events. Results: 72 patients received fixed-dose PCC and 101 received weight-based PCC. Median time between order entry and administration was 4.5 min shorter in the fixed-dose group compared to weight-based (34.5 vs 39 min, P = .10). In patients who received fixed-dose, 79.2% achieved hemostasis versus 71.3% in the weight-based group (RR = 1.11, 95% CI = 0.94-1.32). There was no difference in the number of subsequent hemorrhage-related surgeries (29.2% vs 36.7%, RR = 0.80, 95% CI = 0.51-1.24) or mortality rate (26.4% vs 35.6%, RR = 0.73, 95% CI = 0.46-1.17). There were zero adverse drug events reported. Rates of thrombosis were 2.8% and < 1% (P = .57) in the fixed and weight-based groups, respectively. Conclusion and Relevance: The fixed-dosing strategy did not reduce time to PCC administration nor impact hemostasis or mortality. These data support that the fixed-dosing method is a viable option.

Predictors of adherence to direct oral anticoagulants after cardiovascular or bleeding events in Medicare Advantage Plan enrollees with atrial fibrillation.

BACKGROUND: Direct oral anticoagulants (DOACs) are recommended for patients with atrial fibrillation (AF) given their improved safety profile. Suboptimal adherence to DOACs remains a significant concern among individuals with AF. However, the extent of adherence to DOACs following a cardiovascular or bleeding event has not been fully evaluated. OBJECTIVE: To evaluate the pattern of adherence trajectories of DOACs after a cardiovascular or bleeding event and to investigate the sociodemographic and clinical predictors associated with each adherence trajectory by using claims-based data. METHODS: This retrospective study was conducted among patients with AF prescribed with DOACs (dabigatran/apixaban/rivaroxaban) between July 2016 and December 2017 and who were continuously enrolled in the Texas-based Medicare Advantage Plan. Patients who experienced a cardiovascular or bleeding event while using the DOACs were further included in the analysis. The sample was limited to patients who experienced a clinical event such as a cardiovascular or bleeding event while using the DOACs. The clinical events considered in this study were cardiovascular (stroke, congestive heart failure, myocardial infarction, systemic embolism) and bleeding events. To assess adherence patterns, each patient with a DOAC prescription was followed up for a year after experiencing a clinical event. The monthly adherence to DOACs after these events was evaluated using the proportion of days covered (PDC). A group-based trajectory model incorporated the monthly PDC to classify groups of patients based on their distinct patterns of adherence. Predictors associated with each trajectory were assessed using a multinomial logistic regression model, with the adherent trajectory serving as the reference group in the outcome variable. RESULTS: Among the 694 patients with AF who experienced clinical events after the initiation of DOACs, 3 distinct adherence trajectories were identified: intermediate nonadherent (30.50%), adherent (37.7%), and low adherent (31.8%); the mean PDC was 0.47 for the intermediate nonadherent trajectory, 0.93 for the adherent trajectory, and 0.01 for low adherent trajectory. The low-income subsidy was significantly associated with lower adherence trajectories (odds ratio [OR] = 4.81; 95% CI = 3.07-7.51) and with intermediate nonadherent trajectories (OR = 1.57; 95% CI = 1.06-2.34). Also, nonsteroidal anti-inflammatory drug use was significantly associated with lower adherence trajectories (OR = 5.10; 95% CI = 1.95-13.36) and intermediate nonadherent trajectories (OR = 3.17; 95% CI = 1.26-7.93). Other predictors significantly associated with both nonadherent trajectories are type of DOACs (OR = 0.53; 95% CI = 0.35-0.79), presence of coronary artery disease (OR = 1.89; 95% CI = 1.01-3.55), and having 2 or more clinical events (OR = 1.65; 95% CI = 1.09-2.50). CONCLUSIONS: Predictors identified provide valuable insights into the suboptimal adherence of DOACs among Medicare Advantage Plan enrollees with AF, which can guide the development of targeted interventions to enhance adherence in this high-risk patient population.

Effectiveness of edoxaban in portal vein thrombosis associated with liver cirrhosis.

Portal vein thrombosis (PVT) worsens the long-term prognosis of patients with cirrhosis; however, the optimal treatment remains to be determined. Reports on the efficacy of direct oral anticoagulants are increasing, and further evidence is needed. Therefore, we investigated the effectiveness of treatment with edoxaban in patients with PVT. We retrospectively reviewed the outcomes of edoxaban and warfarin as antithrombotic therapies for PVT. The median overall survival time was 4.2 years in patients with PVT, with a 1-year survival rate of 70.7% and a 5-year survival rate of 47.9%. The leading cause of death was hepatocellular carcinoma. The overall response rate for thrombolysis in the edoxaban group was 76.7% compared to 29.4% in the warfarin group, and edoxaban significantly improved PVT compared to warfarin. In addition, edoxaban provided long-term improvement of PVT. Warfarin, on the other hand, was temporarily effective but did not provide long-term benefits. The Child-Pugh and albumin-bilirubin scores did not change after edoxaban or warfarin use. No deaths occurred due to adverse events associated with edoxaban or warfarin. Edoxaban as a single agent can achieve long-term recanalization without compromising the hepatic reserves. Edoxaban is easy to initiate, even in an outpatient setting, and could become a major therapeutic agent for the treatment of PVT.

Direct Oral Anticoagulation in Lung Transplant Recipients.

OBJECTIVES: Presently, the management of direct oral anticoagulants lacks specific guidelines for patients before and after transplant, particularly for lung transplant recipients. We aimed to consolidate the existing literature on direct oral anticoagulants and explore their implications in lung transplant recipients. MATERIALS AND METHODS: We conducted a comprehensive search in PubMed and Google Scholar databases for studies published between January 2000 and December 2022, using specific search terms. We only included studies involving lung transplant recipients and focusing on direct oral anticoagulants. RESULTS: Five relevant publications were identified, providing varied insights. None of the studies specifically addressed bleeding complications associated with direct oral anticoagulants in lung transplant recipients. Limited details were available on the type of solid-organ transplant or the specific direct oral anticoagulant used in these studies. CONCLUSIONS: Varied bleeding complications associated with direct oral anticoagulants in lung transplant recipients were reported, but studies lacked specificity on transplant type and direct oral anticoagulant variations. Notably, the incidence of venous thrombotic embolism in lung transplant recipients was comparatively higher than in other solid-organ transplant recipients, potentially linked to factors such as corticosteroid therapy, calcineurin inhibitors, and cytomegalovirus infections. Our synthesis on findings of use of direct oral anticoagulant in lung transplant recipients emphasized challenges of managing these medications in urgent transplant situations. Recommendations from experts suggested caution in initiation of direct oral anticoagulants posttransplant until stability in renal and hepatic function is achieved. The limited evidence on safety of direct oral anticoagulants in lung transplant recipients underscores the need for further research and guidance in this specific patient population.

Study Design of a Brazilian Observational Study of Edoxaban in Patients with Atrial Fibrillation (EdoBRA). / Desenho de Estudo de um Estudo Observacional Brasileiro sobre o uso de Edoxabana em Pacientes com Fibrilação Atrial (EdoBRA).

BACKGROUND: Clinical trials showed the safety of Edoxaban, a non-vitamin K-dependent oral anticoagulant (NOAC), and its efficacy to prevent stroke and systemic embolism in non-valvular atrial fibrillation (NVAF) patients and also to prevent and treat venous thromboembolism. However, additional research is needed to evaluate the safety and effectiveness of Edoxaban in a real-world scenario in the Brazilian population. OBJECTIVE: In order to understand the risks and benefits of Edoxaban use in routine clinical settings, the EdoBRA study is being conducted to gain insight into the safety and effectiveness of Edoxaban use in non-preselected patients with NVAF in Brazil. METHODS: The EdoBRA study is a multicenter, prospective, observational study conducted in 36 sites in Brazil. NVAF patients ≥ 18 years treated with commercially available Edoxaban who initiated treatment for at least 14 days and no longer than 90 days prior to enrollment, and who are not simultaneously participating in any interventional study are eligible for this study. Seven hundred patients are planned to be enrolled and one-year of follow up, with data collections expected at baseline and 3, 6, and 12 months after the study enrollment. The primary safety objective is ISTH Clinically Relevant Bleeding, and the secondary effectiveness objective focuses on relevant cardiovascular outcomes related to NVAF. CONCLUSION: EdoBRA observational study will generate relevant additional information about NOAC Edoxaban on various aspects of patient management in routine care, such as its safety and effectiveness profile in patients with NVAF in Brazil.

FUNDAMENTO: Os ensaios clínicos demonstraram a segurança da Edoxabana, um anticoagulante oral não dependente de vitamina K (NOAC), e a sua eficácia na prevenção de acidente vascular cerebral e embolia sistémica em pacientes com fibrilação atrial não valvar (FANV) e também na prevenção e tratamento de tromboembolismo venoso. No entanto, pesquisas adicionais são necessárias para avaliar a segurança e a eficácia da Edoxabana em um cenário real na população brasileira. OBJETIVO: A fim de compreender os riscos e benefícios do uso da Edoxabana em cenários clínicos de rotina, o estudo EdoBRA está sendo conduzido para obter informações sobre a segurança e eficácia do uso da Edoxabana em pacientes não pré-selecionados com FANV no Brasil. MÉTODOS: O estudo EdoBRA é um estudo multicêntrico, prospectivo e observacional, realizado em 36 centros no Brasil. São elegíveis para este estudo pacientes com FANV, ≥ 18 anos de idade, tratados com Edoxabana disponível comercialmente, que iniciaram o tratamento por pelo menos 14 dias e não mais do que 90 dias antes da data de inclusão no estudo, e que não estão participando de nenhum outro estudo de intervenção. Ao todo, 700 pacientes devem ser inscritos e acompanhados por um ano, com coletas de dados programadas para o período basal e 3, 6 e 12 meses após a inscrição no estudo. O objetivo primário de segurança é o sangramento clinicamente relevante (de acordo com critérios da Sociedade Internacional de Trombose e Hemostasia - ISTH), e o objetivo secundário de eficácia são desfechos cardiovasculares relevantes relacionados à FANV. CONCLUSÃO: O estudo observacional EdoBRA gerará informações adicionais relevantes sobre a Edoxabana enquanto NOAC em diversos aspectos do manejo de pacientes no atendimento clínico de rotina, como perfil de segurança e efetividade em pacientes com FANV no Brasil.

Appropriateness of prescribing profiles and intake adherence to non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation: analysis of a retrospective longitudinal study using real-world data from Northern Portugal (AF-React Study).

OBJECTIVES: This study aimed to assess the appropriateness of prescribing profiles and intake adherence to non-vitamin K antagonist oral anticoagulants (NOACs) in patients with atrial fibrillation (AF). DESIGN: Retrospective longitudinal study. SETTING: The study was conducted in the Regional Health Administration of Northern Portugal. PARTICIPANTS: The authors selected a database of 21 854 patients with prescriptions for NOACs between January 2016 and December 2018 and were classified with AF until December 2018. OUTCOME MEASURES: The appropriate dosage of NOAC for patients with AF divided into three categories: contraindicated, inconsistent and consistent, based on the 2020 European Society of Cardiology guidelines for AF. RESULTS: Dabigatran had a lower percentage of guideline-consistent doses (n=1657, 50.1%) than other drugs such as rivaroxaban (n=4737, 81.6%), apixaban (n=3830, 78.7%) and edoxaban (n=436, 82.1%). Most patients with an inconsistent dose were prescribed a lower dose than recommended based on their glomerular filtration rate (GFR). Among patients younger than 75 years with GFR >60 mL/min, 59.8% (n=10 028) had an adequate GFR range, while 27.8% (n=7166) of GFR measurements from patients older than 75 years old and 29.4% (n=913) of GFR measurements from patients younger than 75 years with GFR <60 mL/min were within an adequate time range. Adherence to NOACs varied across different drugs, with 59.1% (n=540) adhering to edoxaban, 56.3% (n=5443) to rivaroxaban, 55.3% (n=3143) to dabigatran and 53.3% (n=4211) to apixaban. CONCLUSIONS: Dabigatran had the lowest percentage of guideline-consistent doses. Patients younger than 75 years with GFR >60 mL/min had the highest percentage with an adequate GFR range, while other groups who require closer GFR monitoring had lower percentages within an adequate GFR range. Adherence to NOACs differed among different drugs, with greater adherence to treatment with edoxaban and less adherence to apixaban.

Cardiovascular impact of cancer in patients with atrial fibrillation on direct oral anticoagulants: a systematic review and meta-analysis

BACKGROUND: The impact of cancer on patients with atrial fibrillation (AF) on direct oral anticoagulants (DOACs) remains a matter of debate. METHODS: We conducted a systematic review and meta-analysis exploring the effect of personal history of cancer in patients with AF on DOACs. PubMed, Embase, and Cochrane databases were searched for relevant studies. We used the random-effects model to calculate the risk ratio (RR) and 95% confidence intervals (CIs). Statistical analyses were performed using RStudio version 4.2.3. RESULTS: A total of six studies were included, with 63,177 patients. The mean age was 74.0 years. In this population of individuals who had AF and took DOACs, a history of cancer was associated with a significant increase in major bleeding (RR 1.72; 95% CI 1.24-2.38; p<0.01), gastrointestinal (GI) bleeding (RR 2.11; 95% CI 1.25-3.57; p<0.01), and any bleeding (RR 1.54; 95% CI 1.39-1.70; p<0.01). Additionally, all-cause death was significantly higher in patients with AF and a history of cancer (RR 1.93; 95% CI 1.35-2.76; p<0.01). There was no significant difference between groups in stroke (RR 1.77; 95% CI 0.66-4.73; p=0.25), cardiovascular (CV) death (RR 0.84; 95% CI 0.57-1.23; p=0.36), or myocardial infarction (MI) (RR 1.21; 95% CI 0.82-1.79; p=0.34). CONCLUSION: Our findings suggest that major bleeding, GI bleeding, any bleeding, and all-cause mortality significantly increased in patients with AF on DOACs who have a personal history of cancer, as compared with those who do not.

Challenges to Laboratory Monitoring of Direct Oral Anticoagulants.

Direct oral anticoagulants (DOACs) exert anticoagulation effect by directly inhibiting Factor Xa (rivaroxaban, apixaban, and edoxaban) or thrombin (dabigatran). Though DOACs are characterized by fixed-dose prescribing and generally do not require routine laboratory drug-level monitoring (DLM), circumstances may arise where the DLM may aid in clinical decision-making, including DOAC dose adjustment, anticoagulant class change, or decisions to withhold or administer reversal agents. We review the current literature that describes high-risk patient groups in which DLM may be beneficial for improved patient anticoagulation management and stewardship. The review also summarizes the limitations of conventional coagulation testing and discuss the emerging utility of quantitative methods for routine and rapid emergent evaluation of DOAC drug levels-in particular, the Anti-Xa activity to detect Factor Xa Inhibitors (rivaroxaban, apixaban, and edoxaban). Both technical and regulatory barriers to widespread DLM implementation are limiting factors to further clinical research that must be overcome, in order to propose universal DOAC DLM strategies and provide clinical-laboratory correlation to formally classify high-risk patient groups.

Use of apixaban in adults with congenital heart disease and atrial arrhythmias: The PROTECT-AR study.

BACKGROUND: Adults with congenital heart disease (ACHD) and atrial arrhythmias (AA) face an increased risk of thromboembolic events. Limited data exist on the use of non-vitamin K oral anticoagulants for thromboprophylaxis in ACHD. We aimed to assess the effectiveness and safety of apixaban in ACHD patients with AA. METHODS: PROTECT-AR (NCT03854149) was a prospective, multicenter, observational study conducted from 2019 to 2023. ACHD patients with atrial fibrillation, atrial flutter, or intra-atrial re-entrant tachycardia on routine apixaban treatment were included. The historical control group consisted of patients previously on vitamin K antagonist (VKA), who were analyzed prior to their transition to apixaban. The primary effectiveness endpoint was the composite of stroke or thromboembolism. The primary safety endpoint was major bleeding. RESULTS: The study enrolled 218 ACHD patients with AA on apixaban, of which 73 were previous VKA users. The analysis covered 527 patient-years of prospective exposure to apixaban and 169 patient-years of retrospective exposure to VKA. The annualized rate of stroke or thromboembolism was 0.6% in the apixaban group and 1.8% in the VKA group (absolute difference - 1.2%; upper limit of one-sided 95% confidence interval [CI] 0.9%, lower than the predefined non-inferiority margin of +1.8%, Pnon-inferiority < 0.001). The annualized rate of major bleeding was 1.5% in the apixaban group and 2.4% in the VKA group (hazard ratio 0.64; 95% CI 0.19-2.10, P = 0.48). CONCLUSION: In ACHD patients with AA, routine apixaban use exhibited a non-inferior rate of stroke or thromboembolism compared to historical VKA use, alongside a similar rate of major bleeding.