Apixaban for Stroke Prevention in Atrial Fibrillation: Why are Event Rates Higher in Clinical Practice than in Randomized Trials?—A Systematic Review

Anticoagulants: From chance discovery to structure-based design

Taking a historical perspective, we review the discovery, pharmacology, and clinical evaluation of the old and new anticoagulants that have been approved for clinical use. The drugs are discussed chronologically, starting in the 1880s, and progressing through to 2024. The innovations in technology used to develop novel anticoagulants came in fits and starts and reflected the advances in science and technology over these decades, whereas the shift from anecdote to evidence-based use of anticoagulants was delayed until the principles of epidemiology and biostatistics were introduced into clinical trial design and to the approval process. Hirudin, heparin, and vitamin K antagonists were discovered by chance, and were used clinically before their mechanism of action was elucidated and before their net clinical benefits were evaluated in randomized clinical trials. Subsequent anticoagulants were designed based on a better understanding of the structure and function of coagulation proteins, including antithrombin, thrombin, and factor Xa, and underwent more rigorous preclinical and clinical evaluation before regulatory approval. By simplifying oral anticoagulation, the direct oral anticoagulants have revolutionized anticoagulation care and have enhanced the uptake of anticoagulation, but bleeding has not been eliminated and there is a need for more effective and convenient anticoagulants for thrombosis triggered by the contact pathway of coagulation. The newly developed factor XIa and XIIa inhibitors have the potential to address these unmet clinical needs and are undergoing clinical evaluation for several indications. SIGNIFICANCE STATEMENT: Anticoagulant therapy is the cornerstone of treatment and prevention of thrombosis, which remains a leading cause of morbidity and mortality worldwide. Elucidation of the structure and function of coagulation enzymes, their cofactors, and inhibitors, coupled with advances in structure-based design led to the discovery of more convenient, safer, and more effective anticoagulants that have revolutionized the management of thrombotic disorders.

Patients with atrial fibrillation and common exclusion criteria from clinical trials are at high risk of clinical events: the Murcia AF Project II (MAFP-II) cohort study

BACKGROUND

Some clinical characteristics and comorbidities in atrial fibrillation (AF) patients are exclusion criteria in randomized clinical trials (RCTs) investigating oral anticoagulants (OAC). However, these conditions are present also in everyday clinical practice patients. We compared the risk of adverse clinical outcomes between patients with and without RCT exclusion criteria.

METHODS

The Murcia AF Project II was an observational cohort study including AF outpatients starting vitamin K antagonists (VKAs) from July 2016 to June 2018. For the selection of the exclusion criteria, the four pivotal RCTs of direct-acting OAC (DOACs) were used as reference. During 2 years, all ischemic strokes/transient ischemic attacks, major adverse cardiovascular events (MACEs), major bleeds, and all-cause deaths were recorded.

RESULTS

1050 patients (51.5% female, median age 77 years) were included, of whom 368 (35%) met at least one exclusion criterion for RCTs. During follow-up, the incidence rate ratios for major bleeding, MACE and all-cause mortality were higher among patients with exclusion criteria (all p < 0.001). Patients fulfilling at least one exclusion criterion had increased risks of major bleeding (aHR 1.48; 95% CI 1.22-1.81; p < 0.001), MACE (aHR 1.51, 95% CI 1.10-2.09, p = 0.012), and mortality (aHR 3.22, 95% CI 2.32-4.48, p < 0.001), as well as a lower event-free survival (all log-rank p < 0.001).

CONCLUSIONS

In this AF cohort taking VKAs, more than one-third had at least one RCT exclusion criteria, which translates into higher risk of major bleeding, MACE, and death. These observations should be considered when translating RCTs results to AF patients for a proper and a more patient-centered management.

Apixaban, edoxaban and rivaroxaban but not dabigatran are associated with higher mortality compared to vitamin-K antagonists: A retrospective German claims data analysis

BACKGROUND

Vitamin-K antagonists (VKAs) have widely been replaced by non-VKA oral anticoagulants (NOACs). This includes Austria, Germany and Switzerland, where as VKA, instead of warfarin, the much longer-acting phenprocoumon is used, which was not compared to NOACs in clinical trials.

METHODS

Using administrative data from a large German health insurance, we included all anticoagulation-naïve patients with a first prescription of a NOAC or VKA between 2012 and 2020. We analysed overall survival, major adverse cardiac and cerebrovascular events, major thromboembolic events and major bleeding.

RESULTS

Overall, 570,137 patients were included (apixaban: 26.9%, dabigatran: 4.6%, edoxaban: 8.8%, rivaroxaban: 39.1% and VKA: 20.7% of these 99.4% phenprocoumon). In the primary analysis using a 1:1 propensity score matching-cohort (PSM-cohort), a significantly higher overall mortality was found for apixaban, edoxaban and rivaroxaban (all p < 0.001) but not for dabigatran (p = 0.13) compared to VKA. In this PSM-cohort, 5-year mortality was 22.7% for apixaban versus 12.7% for VKA, 19.5% for edoxaban versus 11.4% for VKA, 16.0% for rivaroxaban versus 12.3% for VKA (all p < 0.001) and 13.0% for dabigatran versus 12.8% for VKA (p = 0.06). The observed effect was confirmed in sensitivity analyses using un-weighted and three different weighted Fine-Gray regression models on the basis of the entire cohort.

CONCLUSIONS

In this large real-world analysis, apixaban, edoxaban and rivaroxaban, but not dabigatran, were associated with worse survival compared to VKA. These findings, consistent with a few other studies including phenprocoumon, cast profound doubts on the unreflected, general use of NOACs. Randomized trials should assess whether phenprocoumon might actually be superior to NOACs.

Direct Oral Anticoagulants in Older and Frail Patients with Atrial Fibrillation: A Decade of Experience

INTRODUCTION

Both the prevalence of atrial fibrillation (AF) and its subsequent use of direct oral anticoagulants (DOACs) are rapidly increasing in patients of older age. In the absence of contra-indications, guidelines advocate anticoagulation based on the CHA2DS2-VASc score for all AF patients aged 75 and above. However, some practitioners are hesitant to prescribe anticoagulants to older and frail patients due to perceived elevated bleeding risks. This review delves into the comparative treatment outcomes of DOACs versus vitamin K antagonists (VKAs) in older patients with AF, particularly focusing on those of advanced age, frailty, increased risk of falling, chronic kidney disease (CKD), or with a history of major bleeding. Additionally, considerations on the use of off-label DOAC doses, the role of left atrial appendage (LAA) closure and future developments in factor XIa-inhibitors will be discussed.

RESULTS

While strong evidence supports the use of DOACs in the vital older patients with nonvalvular AF, it remains scant in frail patient groups. There is some evidence from non-randomized studies suggesting that the effect of DOACs compared with VKAs is consistent between frail and nonfrail patients. However, recent findings from a single randomized trial showed increased bleeding risks but comparable thromboembolic outcomes in frail individuals switching from VKAs to DOACs. In patients with an increased risk of falling, data suggest no relevant interaction of increased risk of falling on the effectiveness and safety of DOACs compared with warfarin. Resuming oral anticoagulants in patients with Af after major bleeding seems to be beneficial. Off-label low-dose DOAC is often prescribed to patients who were underrepresented in larger randomized trails because of an elevated risk of bleeding or overexposure to DOACs, but its effect on clinical outcomes remains uncertain.

CONCLUSIONS

DOACs are the recommended oral anticoagulant for vital older patients with AF. The scarcity of data backing DOAC use in frail individuals, those with renal impairments, or significant bleeding history underscores the necessity for further investigation. However, existing evidence suggests at least similar effectiveness and safety and potential benefits for DOACs in these patient subsets. Therefore, there is no reason to suggest these patients should be treated differently than the established guidelines regarding anticoagulation.

Oral anticoagulant treatment in atrial fibrillation: the AFIRMA real-world study using natural language processing and machine learning

INTRODUCTION

Oral anticoagulation (OAC) is key in atrial fibrillation (AF) thromboprophylaxis, but Spain lacks substantial real-world evidence. We aimed to analyze the prevalence, clinical characteristics, and treatment patterns among patients with AF undertaking OAC, using natural language processing (NLP) and machine learning (ML).

MATERIALS AND METHODS

This retrospective study included AF patients on OAC from 15 Spanish hospitals (2014-2020). Using EHRead® (including NLP and ML), and SNOMED_CT, we extracted and analyzed patient demographics, comorbidities, and OAC treatment from electronic health records. AF prevalence was estimated, and a descriptive analysis was conducted.

RESULTS

Among 4,664,224 patients in our cohort, AF prevalence ranged from 1.9% to 2.9%. A total of 57,190 patients on OAC therapy were included, 80.7% receiving Vitamin K antagonists (VKA) and 19.3% Direct-acting OAC (DOAC). The median age was 78 and 76 years respectively, with males constituting 53% of the cohort. Comorbidities like hypertension (76.3%), diabetes (48.0%), heart failure (42.2%), and renal disease (18.7%) were common, and more frequent in VKA users. Over 50% had a high CHA2DS2-VASc score. The most frequent treatment switch was from DOAC to acenocoumarol (58.6% to 70.2%). In switches from VKA to DOAC, apixaban was the most chosen (35.2%).

CONCLUSIONS

Utilizing NLP and ML to extract RWD, we established the most comprehensive Spanish cohort of AF patients with OAC to date. Analysis revealed a high AF prevalence, patient complexity, and a marked VKA preference over DOAC. Importantly, in VKA to DOAC transitions, apixaban was the favored option.

Comparing the Real-World and Clinical Trial Bleeding Rates Associated with Oral Anticoagulation Treatment for Atrial Fibrillation

Background The prevention of stroke in patients with atrial fibrillation (AF) involves the use of oral anticoagulation, commonly in the form of direct oral anticoagulants (DOACs). However, it comes with an increased risk of bleeding, and therefore, counselling patients on their individual risks is important. Although the majority of patients initiated on DOACs have been represented within the clinical trials, some cohorts are under-represented in whom clinicians cannot practice evidence-based medicine. Methods Utilising the pooled clinical trial (CT) data sourced from Medidata Enterprise Data Store, five recent open-label industry-sponsored AF trials were compared with real-world data (RWD) sourced from the HealthVerity™ Marketplace with the occurrence of bleeding events as the primary outcome of interest. Results A total of 64,421 patients were included in the analysis, with 3207 patients from the clinical DOAC trials and 61,214 patients from the RWD cohort. Overall, the patients from the RWD cohort had more co-morbidities, were older (72.2 ± 11.9 vs. 65.3 ± 10.7 years old, p < 0.001), had higher mean CHA2DS2VASc (3.98 ± 1.9 vs. 2.87 ± 1.73, p < 0.001), and HAD-BLED scores (2.13 ± 1.02 vs. 1/04 ± 0.93, p < 0.001) when compared to the trial data. When comparing the incidence of the first major bleed at 12 months post-treatment initiation, rates in the RWD cohort were significantly higher (10.69 vs. 18.97 per 100 person-years). The impact of co-morbidities such as age, CHA2DS2VASc, and HAD-BLED scores was similar in both cohorts; however, there was an under-representation of older females and more co-morbid patients within the clinical trial cohort. Conclusions DOAC-treated patients have a higher bleeding incidence rate in the RWD cohort than in clinical trials. This can be explained by the older patient age group with more complex medical h istories and higher HAS-BLED scores. The under-representation of higher-risk patients and lower proportion of females within clinical trials should be addressed to better translate clinical trial data into real-world clinical practice.

Influence of the COVID-19 pandemic on patients receiving oral anticoagulants for the treatment of non-valvular atrial fibrillation

Background

Frequent monitoring of patients declined during the COVID-19 pandemic, harming patients with chronic diseases who critically needed correct monitoring. We evaluated the impact of the COVID-19 pandemic in patients with non-valvular atrial fibrillation (NVAF) receiving treatment with vitamin K antagonists (VKA) or non-vitamin K antagonist oral anticoagulants (NOAC) in clinical practice in Spain.

Methods

This observational, retrospective study analyzed prevalent patients treated with NOAC/VKA on 14/03/2019 (pre-COVID-19 period) and 14/03/2020 (COVID-19 period), who were followed up to 12 months. The study also considered incident patients who started treatment with NOAC/VKA between 15/03/2019 and 13/03/2020 (pre-COVID-19 period) and from 15/03/2020 to 13/03/2021 (COVID-19 period). Demographic characteristics, comorbidities, effectiveness, treatment patterns, and healthcare resource utilization were considered.

Results

Prevalent patients amounted to 12,336 and 13,342 patients, whereas 1,612 and 1,602 incident patients were included in the pre-COVID-19 and COVID-19 periods, respectively. Prevalent patients treated with VKA had more strokes, thromboembolism, and major bleeding compared to those receiving NOAC, particularly during the COVID-19 period. NOAC patients had a 12 % lower risk of death than those on treatment with VKA (Hazard ratio = 0.88 [95 % CI: 0.81 - 0.95], p = 0.033). In addition, VKA patients were less persistent after 12 months than NOAC patients (pre-COVID-19 period: 52.1 % vs. 78.9 %, p < 0.001; COVID-19 period: 49.2 % vs. 80.3 %, p < 0.001), and required more healthcare visits and hospitalizations than those on treatment with NOAC.

Conclusion

Compared to VKA, NOAC seems to have reduced the incidence of severe events and the use of healthcare resources for NVAF, particularly during the pandemic.

Generalisability of trials on antithrombotic treatment intensification in patients with cardiovascular disease

OBJECTIVE

Assessment of generalisability of guideline-informing trials on antithrombotic treatment intensification to real-world patients with cardiovascular disease (CVD).

METHODS

Inclusion and exclusion criteria of the Cardiovascular Outcomes for People Using Anticoagulation Strategies (COMPASS), Clopidogrel for High Atherothrombotic Risk and Ischemic Stabilization, Management and Avoidance (CHARISMA), Prevention of Cardiovascular events in Patients with Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin-Thrombolysis in Myocardial Infarction (PEGASUS-TIMI) and Dual Antiplatelet Therapy (DAPT) study were applied to coronary artery disease (CAD) and/or peripheral artery disease (PAD) patients from Utrecht Cardiovascular Cohort-Second Manifestations of Arterial Disease (UCC-SMART) to determine real-world eligibility. Eligible and ineligible patients were compared on baseline characteristics, cardiovascular events, major bleeding and mortality.

RESULTS

Eligibility ranged from 11%-94% for CAD to 75%-90% for patients with PAD. Cardiovascular, bleeding and mortality risks were higher in COMPASS-eligible patients with CAD (rate ratios (RR) 1.98 (95% CI 1.74 to 2.26), 2.02 (95% CI 1.47 to 2.78) and 3.11 (95% CI 2.71 to 3.57), respectively) and CHARISMA-eligible patients (RR 1.51 (95% CI 1.12 to 2.06), 2.25 (95% CI 1.01 to 6.21) and 4.43 (95% CI 2.79 to 7.51), respectively), and lower in COMPASS-eligible patients with PAD (RR 0.45 (95% CI 0.36 to 0.56), 0.29 (95% CI 0.18 to 0.46) and 0.45 (95% CI 0.38 to 0.54), respectively) and DAPT-eligible patients with CAD (RR CVD 0.49 (95% CI 0.34 to 0.69) and mortality 0.67 (95% CI 0.48 to 0.94)) than ineligible patients. After adjustment for trial eligibility criteria, only higher cardiovascular and mortality risks in COMPASS-eligible patients with CAD and lower cardiovascular risks in CHARISMA-eligible and DAPT-eligible patients persisted with CAD.

CONCLUSION

A large proportion of contemporary CVD patients would be eligible for intensified antithrombotic treatment trials, with mostly similar adjusted event risks to ineligible patients. Trial-based guideline recommendations are largely applicable to real-world patients.

Safety of Direct Oral Anticoagulants for Gastrointestinal Hemorrhage in Patients With Nonvalvular Atrial Fibrillation: A Systematic Review and Meta-analysis of Real-world Studies

GOALS AND BACKGROUND

Since the introduction of Direct Oral Anticoagulants (DOACs), "real-world" studies have investigated their safety profile on gastrointestinal hemorrhage (GIH) when used by patients with Non-Valvular Atrial Fibrillation. We performed a systematic review and meta-analysis to compile and summarize this data after Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

STUDY

Medline and Embase were systematically searched until April 2021. Observational studies that met predefined inclusion criteria were included and hazard ratios (HRs) with 95% CI were extracted. Subgroup analyses based on DOAC doses, history of chronic kidney disease, stroke, prior exposure to VKA (vitamin K antagonist), age, gender, geographic location of population samples, as well as Leave-One-Out and Low/Moderate Risk of Bias sensitivity analyses were performed. A random effects model was used.

RESULTS

A total of 46 studies were included. Apixaban was associated with a reduced risk of GIH compared with Dabigatran (HR: 0.67, 95% CI, 0.56 to 0.81, I2 : 53.28%), Rivaroxaban (HR: 0.56, 95% CI, 0.44 to 0.70, I2 : 79.17%), and VKA (HR: 0.68, 95% CI, 0.60 to 0.78, I2 : 71.93%). Rivaroxaban was associated with increased GIH risk compared with Dabigatran (HR: 1.19, 95% CI, 1.02 to 1.40, I2 : 72.96%) and VKA (HR: 1.16, 95% CI, 1.05 to 1.27, I2 : 81.95%). Dabigatran was associated with similar GIH risk compared with VKA (HR: 1.11, 95% CI, 0.98 to 1.26, I2 : 87.28%).

CONCLUSIONS

Our study shows that Apixaban was associated with a reduction in GIH risk compared with Dabigatran, Rivaroxaban and VKA, whereas Rivaroxaban was associated with an increase in GIH risk compared with both Dabigatran and VKA.

Healthcare resources and costs associated with nonvalvular atrial fibrillation in Spain: apixaban versus acenocoumarol

Aim: Healthcare resources usage and costs associated to nonvalvular atrial fibrillation (NVAF) were analyzed in Spain. Methods: This is an observational and retrospective study on patients with NVAF who started their treatment with apixaban or acenocoumarol between 1 January 2015 and 31 December 2017. Results: 2160 patients treated with apixaban were paired (1:1) with patients treated with acenocoumarol (propensity score matching). Apixaban reduced the incidence of strokes and systemic embolisms, minor and major bleedings and deaths, versus acenocoumarol. Apixaban led to reductions of 80, 55 and 43% in costs related to nursing visits, hospitalizations, and emergency visits, respectively, leading to annual cost savings of €274/patient, from the perspective of society. Conclusion: Our results suggested that apixaban is a cost-effective alternative for patients with NVAF.

Unresolved issues in the use of direct acting oral anticoagulants

INTRODUCTION

Currently approved direct oral anticoagulants (DOACs) target thrombin or coagulation factor Xa. Administered in fixed doses without routine laboratory monitoring, DOACs have simplified the approach to oral anticoagulation, when previously the choice was limited to vitamin K antagonists (VKAs).

AREA COVERED

We discuss a) unresolved issues related to optimal use of DOACs and b) new developments including the potential for FXIa inhibitors to be effective and safer anticoagulants.

EXPERT OPINION

By simplifying oral anticoagulation, DOACs have facilitated the uptake of anticoagulation. The DOACs are approved for stroke prevention in atrial fibrillation and for the prevention and treatment of venous thromboembolism, and their indications are expanding to include the prevention of atherothrombosis. DOACs have now replaced vitamin K antagonists (VKAs) for most indications, but not all. DOACs are inferior to VKAs for patients with mechanical heart valves, left ventricular assist device, rheumatic atrial fibrillation, and those with antiphospholipid syndrome, and their safety and efficacy are uncertain in some populations (e.g. advanced renal and liver disease). Impediments to use include concerns for bleeding and cost. The newly developed FXIa and FXIIa inhibitors have the potential to be safer than current anticoagulants, but phase 3 trials are needed to confirm their clinical efficacy and safety.

Clinical Studies with Anticoagulants that Have Changed Clinical Practice

Anticoagulant therapy is the cornerstone of treatment and prevention of arterial and venous thromboembolism. Taking a historical perspective, starting in the 1960s, and progressing through to 2022, we discuss key clinical trials of anticoagulants that have changed clinical practice, and examine obstacles encountered in bringing these anticoagulants to the clinic. The design of some of the early studies that shaped clinical practice was poor by current standards, but their results were influential because nothing better was available. Both heparin and vitamin K antagonists had been in clinical use for several decades before well-designed trials in the 1980s optimized their dosing and enhanced their safety and efficacy. Low-molecular-weight heparin then replaced unfractionated heparin because it had a more predictable dose-response and a longer half-life, thereby allowing it to be used conveniently in out-of-hospital settings. More recently, direct oral anticoagulants became the oral anticoagulants of choice for most indications because they were shown to be at least as safe and effective as vitamin K antagonists when used in fixed doses without the need for laboratory monitoring. The design of the trials that led to the approval of the direct oral anticoagulants was excellent, but further studies are required to optimize their dosing in selected patients who were underrepresented in these trials.

Clinical outcomes in patients with atrial fibrillation treated with DOACs in a specialized anticoagulation center: Critical appraisal of real-world data

AIMS

Direct oral anticoagulants (DOAC) are progressively replacing vitamin K antagonists in the prevention of thromboembolism in patients with atrial fibrillation. However, their real-world clinical outcomes appear to be contradictory, with some studies reporting fewer and others reporting higher complications than the pivotal randomized controlled trials. We present the results of a clinical model for the management of DOACs in real clinical practice and provide a review of the literature.

METHODS

The MACACOD project is an ongoing, observational, prospective, single-center study with unselected patients that focuses on rigorous DOAC selection, an educational visit, laboratory measurements, and strict follow-up.

RESULTS

A total of 1,259 patients were included. The composite incidence of major complications was 4.93% py in the whole cohort vs 4.49% py in the edoxaban cohort. The rate of all-cause mortality was 6.11% py for all DOACs vs 5.12% py for edoxaban. There weren't differences across sex or between Edoxaban reduced or standard doses. However, there were differences across ages, with a higher incidence of major bleeding complications in patients >85 years (5.13% py vs 1.69% py in <75 years).

CONCLUSIONS

We observed an incidence of serious complications of 4.93% py, in which severe bleeding predominated (3.65% py). Considering our results, more specialized attention seems necessary to reduce the incidence of severe complications and also a more critical view of the literature. Considering our results, and our indirect comparison with many real-world studies, more specialized attention seems necessary to reduce the incidence of severe complications in AF patients receiving DOACs.

Managing high-risk atrial fibrillation patients with multiple comorbidities

Atrial fibrillation (AF) patients are often high risk being elderly and having multiple comorbidities. Many risk factors are established to be associated with new onset incident AF, as well as AF-related complications such as stroke and hospitalisations. Multimorbidity AF patients are high risk and require a holistic approach to care, which should be proactively managing with an integrated care or holistic approach as per the ABC (atrial fibrillation better care) pathway.

Effectiveness and safety of low-dose versus standard-dose rivaroxaban and apixaban in patients with atrial fibrillation

BACKGROUND

Low-dose direct oral anticoagulant (DOAC) use is quite prevalent in clinical practice, but evidence of its effectiveness and safety compared with high-dose DOAC in patients with atrial fibrillation (AF) remains limited. We aimed to assess the effectiveness and safety of low-dose and high-dose DOACs in patients with AF with similar baseline characteristics.

METHODS

We used a cohort of hospitalized patients with a primary or secondary diagnosis of AF after discharge to the community, whose data were stored in the Quebec administrative databases, from 2011 to 2017. Older adults with AF newly prescribed with rivaroxaban (15 or 20 mg) or apixaban (2.5 mg or 5 mg) were classified as under treatment (UT) and intent to treat (ITT). We used an inverse probability treatment weighting study of new users of rivaroxaban and apixaban to address confounding by indication. The primary effectiveness outcome was ischemic stroke/systemic embolism (SE), while the primary safety outcome was major bleeding (MB). We used Cox proportional models to estimate the marginal hazard ratios (HRs).

FINDINGS

A total of 1,722 and 4,639 patients used low-dose and standard-dose rivaroxaban, respectively, while 3,833 and 6,773 patients used low-dose and standard-dose apixaban, respectively. No significant difference was observed in the incidence of comparative stroke/SE and MB between low-dose and standard-dose rivaroxaban, except for the risk of acute myocardial infarction (AMI), which was increased with the low dose in the UT analysis. For apixaban, no difference was found in the bleeding rates, but the risk of stroke/SE (HR: 1.95; 95% confidence interval (CI): 1.38-2.76) and death (HR: 1.99; 95% CI: 1.46-2.70) were greater in the low-dose group than in the standard-dose group in the UT analysis. Similar results were observed for the ITT analysis.

CONCLUSION

No significant differences were observed in the effectiveness or safety outcome between low-dose and standard-dose rivaroxaban, except for AMI. However, low-dose apixaban was associated with a greater risk of stroke/SE and death without a reduction in the bleeding rates.

Trends of use and factors that determine the choice of oral anticoagulants in women and men with atrial fibrillation

The aim was to identify sex-specific factors linked with oral anticoagulant initiation in a cohort of patients with atrial fibrillation using administrative data from Quebec (Canada) between 2014 and 2017. Cohort entry defined as new users, that is, no claims in last 12 months, a cohort of 32 050 patients was stratified in two groups, that is, women and men. Multivariable regression models were used to identify factors of initiations for low- and standard-dose direct oral anticoagulants (DOACs) versus warfarin, and low- versus standard-dose DOACs. In both sexes, warfarin initiation decreased and DOAC initiation increased, with year of initiation as major factors of DOACs use. In 2017, the increase was of 2- to 4-fold and 3- to 8-fold for low- and standard-dose DOACs (vs. warfarin), respectively. The proportion of patients starting on a low-dose DOAC was higher in women than men. Older age for both sexes and CHADS2 score ≥2 (only women) were major factors of low-dose dabigatran and rivaroxaban versus warfarin use. The only significant factor of standard-dose DOAC versus warfarin use was age of 65-79 for women or men treated with apixaban by 1.8- and 1.4-fold, respectively. Factors that made women and men less likely to receive a standard-dose DOAC versus warfarin were higher CHADS2 (for dabigatran and rivaroxaban), HAS-BLED and frailty scores, prior coronary disease, major bleeding, and chronic kidney disease (CKD) status. The choice of a low- versus standard-dose DOAC was mainly driven by age and CKD, and higher CHADS2 score (for dabigatran and apixaban) for both sexes.

A comparison of front-line oral anticoagulants for the treatment of non-valvular atrial fibrillation: Effectiveness and safety of direct oral anticoagulants in the FANTASIIA registry

INTRODUCTION

For a long time, vitamin K antagonists (VKA) were the only oral anticoagulation therapy available to reduce adverse events in atrial fibrillation (AF) patients. Direct-acting oral anticoagulants (DOAC) are at least as effective and safe as VKA with few drug interactions, rapid onset and short half-life. Four DOACs, dabigatran, apixaban, rivaroxaban and edoxaban have demonstrated efficacy and safety for treatment in AF patients.

AREAS COVERED

The purpose of this review article is to analyze the current evidence in clinical trials and in real-world populations and performed a new analysis with the estimated effect of those DOACs over the VKA population from the FANTASIIA registry. We present in this manuscript original data analysis from FANTASIIA population as well as data obtained through a search of PubMed for the clinical trials comparing DOAC in the main randomized trials of each DOAC and observational data of the real-world effects of DOACs compared to VKAs.

EXPERT OPINION

In the absence of randomized, controlled head-to-head comparisons between DOACs, high-quality observational data can provide useful information on the comparative effectiveness of DOACs. Current clinical guidelines recommend the management of oral anticoagulation in AF patients with DOACs over VKA for stroke prevention; however, many guidelines generally do not suggest a specific DOAC choice in clinical practice. The revised evidence in this manuscript and our real experience reflects that apixaban and dabigatran show the best efficacy and safety profile.

Global Oral Anticoagulation Use Varies by Region in Patients With Recent Diagnosis of Atrial Fibrillation: The GLORIA-AF Phase III Registry

Background Effective stroke prevention with oral anticoagulants (OAC) is recommended for some patients with atrial fibrillation (AF). We aimed to describe OAC use by geographical region and type of site in patients with recent-onset AF enrolled in a large global registry. Methods and Results Eligible participants were recruited into GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation), a prospective observational cohort study from 2014 to 2016 in 4 international regions: North America, Europe, Asia, and Latin America. Cumulative incidence functions were generated for direct OACs (DOAC), vitamin K antagonists, and antiplatelet drugs considering competing risks, stratified by region and type of site. Time-to-treatment initiation after AF diagnosis was analyzed with Fine-Gray subdistribution hazard models. A total of 21 237 patients eligible for analysis were identified. By 30 days after AF diagnosis, 40%, 16%, and 8.6% of patients had DOAC, vitamin K antagonists, and antiplatelet drugs initiated, respectively. Earlier initiation of DOACs was observed in Europe, with Asia and Latin America having lower hazard rates of DOAC time-to-treatment initiation than Europe (hazard ratio [HR], 0.66; 95% CI, 0.62-0.70 and HR, 0.79; 95% CI, 0.73-0.85, respectively). DOAC initiation was highest in community hospitals, vitamin K antagonists in outpatient health care centers/anticoagulation clinics, and antiplatelet drugs in primary care clinics. Conclusions Important geographic variability exists with the use of OACs for patients with AF. Differences in the time-to-treatment initiation of OAC by type of site suggests suboptimal implementation of guideline recommendations and could result in less benefit and more harm. Optimizing OAC use for patients with AF may improve outcomes and reduce health care costs. Registration URL: http://www.clinicaltrials.gov; Unique identifiers: NCT01468701, NCT01671007.

Growth differentiation factor 15 (GDF-15) in cardiovascular diseases: predicting bleeding after cardiac surgery and beyond that!

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Can a Single Measurement of Apixaban Levels Identify Patients at Risk of Overexposure? A Prospective Cohort Study

Background Patients with atrial fibrillation (AF) are frequently treated with apixaban 2.5-mg twice daily (BID) off-label, presumably to reduce the bleeding risk. However, this approach has the potential to increase the risk of ischemic stroke. If a single measurement could reliably identify patients with high drug levels, the increased stroke risk may be mitigated by confining off-label dose reduction to such patients.

Objectives This study aimed to determine whether a single high apixaban level is predictive of a similarly high level when the test is repeated in 2 months.

Methods In this prospective cohort study of clinic patients receiving apixaban 5-mg BID for AF or venous thromboembolism, peak and trough apixaban levels were measured using the STA-Liquid anti-Xa assay at baseline and 2 months. We calculated the proportions of patients with levels that remained in the upper quintile.

Results Of 100 enrolled patients, 82 came for a second visit, 55 of whom were treated with apixaban 5-mg BID. Seven (63.6%, 95% confidence interval [CI]: 35.4–84.8%) and nine (81.8%, 95% CI: 52.3–94.9%) of 11 patients with a baseline trough and peak level in the upper quintile, respectively, had a subsequent level that remained within this range. Only one (9.1%, 95% CI: 1.6–37.7%) patient had a subsequent level that fell just lower than the median.

Conclusion The trough and peak levels of apixaban in patients who have a high level on a single occasion, usually remain high when the assay is repeated in 2 months. Accordingly, the finding of a high apixaban level in patients deemed to be at high risk of bleeding, allows physicians contemplating off-label use of the 2.5-mg BID dose to limit its use to selected patients who are less likely to be exposed to an increased risk of thrombosis.

Real-world safety and efficacy of direct oral anticoagulants in atrial fibrillation: a systematic review and meta-analysis of 605 771 patients

AIMS

To analyse the safety and efficacy of direct oral anticoagulants (DOACs) in real-world studies including atrial fibrillation (AF) patients.

METHODS AND RESULTS

Systematic review and meta-analysis of observational studies including AF patients on DOACs. Primary endpoints: any, major, gastrointestinal (GI), intracranial haemorrhage (ICH), and haemorrhagic stroke (HS). Secondary endpoints: ischaemic stroke (IS), systemic embolism (SE), myocardial infarction (MI), and all-cause of death. A set of pair-wise meta-analyses using a random effect model and a random effect network meta-analysis under a Bayesian framework were performed. Prospero registration number: CRD42019137111. We included 21 studies with 605 771 AF patients. Apixaban was associated with lower major and GI bleeding compared with Rivaroxaban [hazard ratio (HR) 2.0, 95% confidence interval (CI) 1.6-2.5] and Dabigatran (HR 1.6, 95% CI 1.3-2.1). The latter drug performed better than Rivaroxaban (HR 1.2, 95% CI 1.0-1.5). Dabigatran and Apixaban had a similar association with HS, but Apixaban performed better than Rivaroxaban (HR 1.8, 95% CI 1.1-3.0). Apixaban had a similar association with Rivaroxaban and Dabigatran for ICH, the latter drug performing better than Rivaroxaban (HR 1.3, 95% CI 1.0-1.7). Rankograms showed that Apixaban was likely to be the first-choice treatment in relation to any (65%) major (100%) and GI bleeding (100%) followed by Dabigatran (46%, 100%, 99%, respectively). Dabigatran and Apixaban had similar rank as first choice for ICH (44% and 55%) and HS (52% and 48%). DOACs showed similar association with IS/SE, MI, all-cause of death.

CONCLUSIONS

Analysis of real-world studies shows significant differences for safety among DOACs.

Off-label underdosed apixaban use in Asian patients with non-valvular atrial fibrillation

AIMS

To compare the effectiveness and safety of off-label underdosed apixaban with on-label standard dose apixaban in Asian patients with atrial fibrillation (AF).

METHODS AND RESULTS

Using the Korean nationwide claims database, we identified patients who were prescribed apixaban and did not fulfil the dose reduction criteria for apixaban between January 2015 and December 2017. A multivariable Cox hazard regression model was performed, and hazard ratios (HRs) for ischemic stroke, major bleeding (MB), all-cause death, and composite outcome were analysed. Compared to patients prescribed on-label standard dose apixaban (n = 4,194), patients prescribed off-label underdosed apixaban (n = 2,890) showed a higher risk of ischemic stroke (adjusted HR [aHR], 1.38; 95% confidence interval [CI], 1.06-1.81), all-cause death (aHR, 1.19; 95% CI, 1.01-1.39), and the composite outcome (aHR, 1.17; 95% CI, 1.03-1.34), but with no significant differences in MB between the two groups. Among the patients who did not meet any dose reduction criteria, off-label underdosed apixaban use was associated with a significantly higher risk of ischemic stroke than on-label standard dose apixaban use (aHR, 1.85; 95% CI, 1.25-2.73). Among the patients who met a single dose reduction criterion, off-label underdosed apixaban use was associated with a higher risk of all-cause death than on-label standard dose apixaban (aHR, 1.32; 95% CI, 1.07-1.64).

CONCLUSION

The off-label underdosed apixaban group showed higher risks of ischemic stroke, all-cause death, and composite clinical outcomes than the on-label standard dose apixaban group, but both showed comparable risks of MB. Label-adherence to apixaban dosing should be emphasised to achieve the best clinical outcomes for Asian patients with AF.