Direct oral anticoagulants: integration into clinical practice

The introduction of direct oral anticoagulants (OACs) for the treatment and prevention of thromboembolic disease represents a shift from the traditional vitamin K antagonist-based therapies, which have been the mainstay of treatment for almost 60 years. A challenge for hospital formularies will be to manage the use of direct OACs from hospital to outpatient settings. Three direct OACs—apixaban, dabigatran and rivaroxaban—are widely approved across different indications, with rivaroxaban approved across the widest breadth of indications. A fourth direct OAC, edoxaban, has also completed phase III trials. Implementation of these agents by physicians will require an understanding of the efficacy and safety profile of these drugs, as well as an awareness of renal function, comedication use, patient adherence and compliance. Optimal implementation of direct OACs in the hospital setting will provide improved patient outcomes when compared with traditional anticoagulants and will simplify the treatment and prevention of thromboembolic diseases.

Evidence-to-practice gaps in post-stroke management: a focus on care in a stroke unit and anticoagulation to prevent death, disability and recurrent stroke

ABSTRACT: 

The global burden of stroke is large. Over the last 15 years significant advances have been made to improve acute stroke care and prevention management providing the ability to mitigate much of this burden. In this article, we describe the importance of two main elements of stroke care: stroke units to reduce death and disability and anticoagulation therapy to prevent recurrent, often fatal or disabling, cardioembolic stroke. We also describe the issues related to translating these interventions into practice and the related economic implications. Despite the proven effectiveness and cost–effectiveness of these and other interventions, many people experiencing stroke are not receiving these interventions. Effective evidence translation initiatives and routine monitoring of healthcare is needed to address important gaps in stroke management in promoting societal well-being.

[Novel oral anticoagulants in patients with atrial fibrillation, how to avoid accidents?]

Know the indications of these new drugs, and respect them. Do not confuse easiness of administration and absence of precautions. Renal function: a key parameter before and during treatment. Know when to use a low-dose drug regimen. Cardioversion: lack of safety evidence for some drugs. Drug interactions: beware of P-glycoprotein and cytochrome P450.

Edoxaban in the evolving scenario of non vitamin K antagonist oral anticoagulants imputed placebo analysis and multiple treatment comparisons

Background

Edoxaban recently proved non-inferior to warfarin for prevention of thromboembolism in patients with non-valvular atrial fibrillation (AF). We conducted an imputed-placebo analysis with estimates of the proportion of warfarin effect preserved by each non vitamin K antagonist oral anticoagulant (NOAC) and indirect comparisons between edoxaban and different NOACs.

Methods and Findings

We performed a literature search (up to January 2014), clinical trials registers, conference proceedings, and websites of regulatory agencies. We selected non-inferiority randomised controlled phase III trials of dabigatran, rivaroxaban, apixaban and edoxaban compared with adjusted-dose warfarin in non-valvular AF. Compared to imputed placebo, all NOACs reduced the risk of stroke (ORs between 0.24 and 0.42, all p<0.001) and all-cause mortality (ORs between 0.55 and 0.59, all p<0.05). Edoxaban 30 mg and 60 mg preserved 87% and 112%, respectively, of the protective effect of warfarin on stroke, and 133% and 121%, respectively, of the protective effect of warfarin on all-cause mortality. The risk of primary outcome (stroke/systemic embolism), all strokes and ischemic strokes was significantly higher with edoxaban 30 mg than dabigatran 150 mg and apixaban. There were no significant differences between edoxaban 60 mg and other NOACs for all efficacy outcomes except stroke, which was higher with edoxaban 60 mg than dabigatran 150 mg. The risk of major bleedings was lower with edoxaban 30 mg than any other NOAC, odds ratios (ORs) ranging between 0.45 and 0.67 (all p<0.001).

Conclusions

This study suggests that all NOACs preserve a substantial or even larger proportion of the protective warfarin effect on stroke and all-cause mortality. Edoxaban 30 mg is associated with a definitely lower risk of major bleedings than other NOACs. This is counterbalanced by a lower efficacy in the prevention of thromboembolism, although with a final benefit on all-cause mortality.

Impact of stated barriers on proposed warfarin prescription for atrial fibrillation: a survey of Canadian physicians

BACKGROUND

Atrial fibrillation (AF) is a common cardiac arrhythmia, and leading cause of ischemic stroke. Despite proven effectiveness, warfarin remains an under-used treatment in atrial fibrillation patients. We sought to study, across three physician specialties, a range of factors that have been argued to have a disproportionate effect on treatment decisions.

METHODS

Cross-sectional survey of Canadian Family Doctors (FD: n = 500), Geriatricians (G: n = 149), and Internal Medicine specialists (IMS: n = 500). Of these, 1032 physicians were contactable, and 335 completed and usable responses were received. Survey questions and clinical vignettes asked about the frequency with which they see patients with atrial fibrillation, treatment practices, and barriers to the prescription of anticoagulants.

RESULTS

Stated prescribing practices did not significantly differ between physician groups. Falls risk, bleeding risk and poor patient adherence were all highly cited barriers to prescribing warfarin. Fewer geriatricians indicated that history of patient falls would be a reason for not treating with warfarin (G: 47%; FD: 71%; IMS: 72%), and significantly fewer changed reported practice in the presence of falls risk (χ (2) (6) = 45.446, p < 0.01). Experience of a patient having a stroke whilst not on warfarin had a significant impact on vignette decisions; physicians who had had patients who experienced a stroke were more likely to prescribe warfarin (χ (2) (3) =10.7, p = 0.013).

CONCLUSIONS

Barriers to treatment of atrial fibrillation with warfarin affect physician specialties to different extents. Prior experience of a patient suffering a stroke when not prescribed warfarin is positively associated with intention to prescribe warfarin, even in the presence of falls risk.

Measures of vitamin K antagonist control reported in atrial fibrillation and venous thromboembolism studies: a systematic review

OBJECTIVE

To aid trialists, systematic reviewers and others, we evaluated the degree of standardisation of control measure reporting that has occurred in atrial fibrillation (AF) and venous thromboembolism (VTE) studies since 2000; and attempted to determine whether the prior recommendation of reporting ≥2 measures per study has been employed.

DESIGN

Systematic review.

SEARCH STRATEGY

We searched bibliographic databases (2000 to June 2013) to identify AF and VTE studies evaluating dose-adjusted vitamin K antagonists (VKAs) and reporting ≥1 control measure. The types of measures reported, proportion of studies reporting ≥2 measures and mean (±SD) number of measures per study were determined for all studies and compared between subgroups.

DATA EXTRACTION

Through the use of a standardised data extraction tool, we independently extracted all data, with disagreements resolved by a separate investigator.

RESULTS

148 studies were included, 57% of which reported ≥2 control measures (mean/study=2.13±1.36). The proportion of time spent in the target international normalised ratio range (TTR) was most commonly reported (79%), and was frequently accompanied by time above/below range (52%). AF studies more frequently reported ≥2 control measures compared with VTE studies (63% vs 37%; p=0.004), and reported a greater number of measures per study (mean=2.36 vs 1.53; p<0.001). Observational studies were more likely to provide ≥2 measures compared with randomised trials (76% vs 33%; p<0.001) and report a greater number of measures (mean=2.58 vs 1.63; p<0.001). More recent studies (2004-2013) reported ≥2 measures more often than older (2000-2003) studies (59% vs 35%; p=0.05) and reported more measures per study (mean=2.23 vs 1.48; p=0.02).

CONCLUSIONS

While TTR was often utilised, studies reported ≥2 measures of VKA control only about half of the time and lacked consistency in the types of measures reported. A trend towards studies reporting greater numbers of VKA control measures over time was observed over our review time horizon, particularly, with AF and observational studies.

New oral anticoagulants in patients with nonvalvular atrial fibrillation: a review of pharmacokinetics, safety, efficacy, quality of life, and cost effectiveness

Atrial fibrillation (AF) continues to be a leading cause of cerebrovascular morbidity and mortality resulting from cardioembolic stroke. Oral anticoagulation therapy has been shown to decrease the incidence of cardioembolic stroke in patients with AF by more than 50%. Appropriate use of anticoagulation with vitamin K antagonists requires precise adherence and monitoring. A number of factors that potentially induce patients’ dissatisfaction reduce quality of patient life. New direct oral anticoagulants, such as the direct factor Xa inhibitors rivaroxaban, apixaban, edoxaban, and the thrombin inhibitor dabigatran, were developed to overcome the limitations of the conventional anticoagulant drugs. However, models to optimize the benefit of therapy and to ensure that therapy can be safely continued are missing for the new oral anticoagulants. This review will briefly describe the new oral anticoagulants dabigatran, rivaroxaban, apixaban, and edoxaban with focus on their use for prevention of embolic events in AF. Moreover, it will discuss the safety, efficacy, cost data, and benefit for patients’ quality of life and adherence.

Twice- or once-daily dosing of novel oral anticoagulants for stroke prevention: a fixed-effects meta-analysis with predefined heterogeneity quality criteria

Background

A number of novel oral anticoagulants (direct thrombin inhibitors or factor Xa inhibitors) are in clinical use for various indications. The dosing regimens differ between twice-daily and once-daily dosing for the prevention of stroke in patients with atrial fibrillation. With the availability of the results from four phase 3 studies (>70,000 patients), we explored whether twice-daily or once-daily dosing provides better risk-benefit balance among novel oral anticoagulants.

Methods

We conducted a strict, stepwise, fixed-effects meta-analysis with predefined heterogeneity quality criteria to generate the most appropriate common estimates for twice-daily (BID) or once-daily (QD) dosing regimens. An indirect comparison of these dosing regimens with fixed-effects meta-analysis common estimates (where available), or individual compound results, was done respectively.

Results

Comparing indirectly BID vs QD dosing regimens resulted in hazard ratios (HR [95% confidence interval]) for stroke and systemic embolism of 0.75 (0.58–0.96) for dabigatran 150 mg BID, and 0.91 (0.73–1.13) for apixaban BID vs the QD dosing regimen. For ischemic stroke, the HR of BID vs QD was 0.85 (0.69–1.05). For intracranial hemorrhage, BID vs rivaroxaban QD was 0.57 (0.37–0.88) and, vs edoxaban QD, 0.81 (0.54–1.22). Due to heterogeneity, common estimates for major bleeding QD or BID were not justified, therefore indirect comparison of regimens were not possible. All non-vitamin K antagonist oral anticoagulants reduced all-cause mortality vs warfarin with a HR of 0.90 (0.86–0.96) without differences between regimen.

Conclusions

Based on the available phase 3 study evidence, the twice-daily dosing regimen of non-vitamin K antagonist oral anticoagulants appears to offer a more balanced risk-benefit profile with respect to stroke prevention and intracranial hemorrhage.

Dabigatran etexilate and risk of myocardial infarction, other cardiovascular events, major bleeding, and all-cause mortality: a systematic review and meta-analysis of randomized controlled trials

Background

Signals of an increased risk of myocardial infarction (MI) have been identified with dabigatran etexilate in randomized controlled trials (RCTs).

Methods and Resules

We conducted searches of the published literature and a clinical trials registry maintained by the drug manufacturer. Criteria for inclusion in our meta‐analysis included all RCTs and the availability of outcome data for MI, other cardiovascular events, major bleeding, and all‐cause mortality. Among the 501 unique references identified, 14 RCTs fulfilled the inclusion criteria. Stratification analyses by comparators and doses of dabigatran etexilate were conducted. Peto odds ratio (OR_PETO) values using the fixed‐effect model (FEM) for MI, other cardiovascular events, major bleeding, and all‐cause mortality were 1.34 (95% CI 1.08 to 1.65, P=0.007), 0.93 (95%CI 0.83 to 1.06, P=0.270), 0.88 (95% CI 0.79 to 0.99, P=0.029), and 0.89 (95% CI 0.80 to 1.00, P=0.041). When compared with warfarin, OR_PETO values using FEM were 1.41 (95% CI 1.11 to 1.80, P=0.005), 0.94 (95%CI 0.83 to 1.06, P=0.293), 0.85 (95% CI 0.76 to 0.96, P=0.007), and 0.90 (95% CI 0.81 to 1.01, P=0.061), respectively. In RCTs using the 150‐mg BID dosage, the OR_PETO values using FEM were 1.45 (95% CI 1.11 to 1.91, P=0.007), 0.95 (95% CI 0.82 to 1.09, P=0.423), 0.92 (95% CI 0.81 to 1.05, P=0.228), and 0.88 (95% CI 0.78 to 1.00, P=0.045), respectively. The results of the 110‐mg BID dosage were mainly driven by the RE‐LY trial.

Conclusions

This meta‐analysis provides evidence that dabigatran etexilate is associated with a significantly increased risk of MI. This increased risk should be considered taking into account the overall benefit in terms of major bleeding and all‐cause mortality.

Personalized approach to primary and secondary prevention of ischemic stroke

Primary and secondary prevention of ischemic stroke represents a significant part of stroke management and health care. Although there are official guidelines concerning stroke management, new knowledge are introduced to them with a slight delay. This article provides an overview of current information on primary and secondary prevention of ischemic stroke. It summarizes information especially in the field of cardioembolic stroke, the use of new anticoagulants and the management of carotid stenosis based on the results of recent clinical studies. The optimal approach in stroke management is to follow these recommendations, to know new strategies and to apply an individual personalized approach in our clinical decisions.

Systematic review and network meta-analysis comparing antithrombotic agents for the prevention of stroke and major bleeding in patients with atrial fibrillation

OBJECTIVE

To examine the comparative efficacy and safety of antithrombotic treatments (apixaban, dabigatran, edoxaban, rivaroxaban and vitamin K antagonists (VKA) at a standard adjusted dose (target international normalised ratio 2.0-3.0), acetylsalicylic acid (ASA), ASA and clopidogrel) for non-valvular atrial fibrillation and among subpopulations.

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

A systematic literature search strategy was designed and carried out using MEDLINE, EMBASE, the Cochrane Register of Controlled Trials and the grey literature including the websites of regulatory agencies and health technology assessment organisations for trials published in English from 1988 to January 2014.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials were selected for inclusion if they were published in English, included at least one antithrombotic treatment and involved patients with non-valvular atrial fibrillation eligible to receive anticoagulant therapy.

RESULTS

For stroke or systemic embolism, dabigatran 150 mg and apixaban twice daily were associated with reductions relative to standard adjusted dose VKA, whereas low-dose ASA and the combination of clopidogrel plus low-dose ASA were associated with increases. Absolute risk reductions ranged from 6 fewer events per 1000 patients treated for dabigatran 150 mg twice daily to 15 more events for clopidogrel plus ASA. For major bleeding, edoxaban 30 mg daily, apixaban, edoxaban 60 mg daily and dabigatran 110 mg twice daily were associated with reductions compared to standard adjusted dose VKA. Absolute risk reductions with these agents ranged from 18 fewer per 1000 patients treated each year for edoxaban 30 mg daily to 24 more for medium dose ASA.

CONCLUSIONS

Compared with standard adjusted dose VKA, new oral anticoagulants were associated with modest reductions in the absolute risk of stroke and major bleeding. People on antiplatelet drugs experienced more strokes compared with anticoagulant drugs without any reduction in bleeding risk. To fully elucidate the comparative benefits and harms of antithrombotic agents across the various subpopulations, rigorously conducted comparative studies or network meta-regression analyses of patient-level data are required.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO registry-CRD42012002721.

The clinical impact of different coagulometers on patient outcomes

Introduction

Long-term anticoagulation therapy using vitamin K antagonists (VKA) is used in millions of patients worldwide to reduce the risk of thrombotic or thromboembolic events. Control and monitoring of VKA therapy is improved by the regular self-measurement of international normalized ratio (INR) using a home monitoring device. This retrospective analysis of a large cohort of patients in the Netherlands seeks to determine whether the choice of INR monitor could have a clinical impact on patient outcomes.

Methods

The National Thrombosis Service provides medical supervision, training and support to anticoagulant patients eligible for home-monitoring of INR in the Netherlands. Two INR monitors (CoaguChek XS and INRatio2) have been distributed at random to patients since June 2011, and patient self-testing data (INR measurements and other clinical parameters) have been recorded to measure and improve treatment outcomes. The data have been retrospectively analyzed to determine any effect of the choice of monitor. Univariate and multivariate statistical tests are used to assess any differences between groups in terms of efficacy and safety parameters.

Results

Data from 4,326 patients were collated, and 156,507 INR values were included in the analysis. Over half the patients (54.3%) were being treated for atrial fibrillation, and 77.6% were prescribed acenocoumarol. There were few differences between the patient populations using the two different monitors. Anticoagulant control overall was good, with high percentage of time (87.9%) in the appropriate INR range and low incidence of excessively high or low INR values (0.085/month). Minor clinical events related to safety were low (0.78 per patient-year) and showed few differences between monitors. Mortality rates were similar [hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.65–1.70].

Conclusion

Self-testing data from a large cohort of patients in the Netherlands suggest that there is no clinically relevant effect of the choice of coagulation monitor (CoaguChek XS or INRatio2) on the time in therapeutic range (TTR), minor or fatal outcomes of long-term anticoagulation management.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-014-0124-x) contains supplementary material, which is available to authorized users.

New oral anticoagulants may be particularly useful for asian stroke patients

Atrial fibrillation (AF) is an emerging epidemic in both high-income and low-income countries, mainly because of global population aging. Stroke is a major complication of AF, and AF-related ischemic stroke is more disabling and more fatal than other types of ischemic stroke. However, because of concerns about bleeding complications, particularly intracranial hemorrhage, and the limitations of a narrow therapeutic window, warfarin is underused. Four large phase III randomized controlled trials in patients with non-valvular AF (RE-LY, ROCKET-AF, ARISTOTLE, and ENGAGE-AF-TIMI 48) demonstrated that new oral anticoagulants (NOACs) are superior or non-inferior to warfarin as regards their efficacy in preventing ischemic stroke and systemic embolism, and superior to warfarin in terms of intracranial hemorrhage. Among AF patients receiving warfarin, Asians compared to non-Asians are at higher risk of stroke or systemic embolism and are also more prone to develop major bleeding complications, including intracranial hemorrhage. The extra benefit offered by NOACs over warfarin appears to be greater in Asians than in non-Asians. In addition, Asians are less compliant, partly because of the frequent use of herbal remedies. Therefore, NOACs compared to warfarin may be safer and more useful in Asians than in non-Asians, especially in stroke patients. Although the use of NOACs in AF patients is rapidly increasing, guidelines for the insurance reimbursement of NOACs have not been resolved, partly because of insufficient understanding of the benefit of NOACs and partly because of cost concerns. The cost-effectiveness of NOACs has been well demonstrated in the healthcare settings of developed countries, and its magnitude would vary depending on population characteristics as well as treatment cost. Therefore, academic societies and regulatory authorities should work together to formulate a scientific healthcare policy that will effectively reduce the burden of AF-related stroke in this rapidly aging society.

Controversies regarding the new oral anticoagulants for stroke prevention in patients with atrial fibrillation

Increasing use of the new oral anticoagulants (NOACs) – dabigatran, rivaroxaban, and apixaban – has prompted considerable discussion in the medical community even as warfarin remains the mainstay of therapy. This article raises 10 controversial issues regarding the use of NOACs for stroke prevention in patients with atrial fibrillation, and offers a review of the latest available evidence. We provide a brief overview of the mechanism and dosing of these drugs, as well as a summary of the key clinical trials that have brought them into the spotlight. Comparative considerations relative to warfarin such as NOAC safety, efficacy, bleeding risk, reversibility, drug-transitioning and use in patients well controlled on warfarin are addressed. Use in select populations such as the elderly, those with coronary disease, renal impairment, or on multiple anti-platelet drugs is also discussed. Finally, we consider such specific issues as comparative efficacy, off-label use, cost, rebound and management during events. Ultimately, the rise of the NOACs to mainstream use will depend on further data and clinical experience amongst the medical community.

Management of Atrial Fibrillation

Atrial fibrillation remains the most prevalent cardiac arrhythmia, and its incidence is increasing as the population ages. Common conditions associated with an increased incidence include advanced age, hypertension, heart failure, and valvular heart disease. Patients with atrial fibrillation may complain of palpitations, fatigue, and decreased exercise tolerance or may be completely asymptomatic. Options for treating patients who experience atrial fibrillation include rate-controlling drugs such as digoxin, β-blockers, and calcium channel blockers or a rhythm-controlling strategy with agents such as sodium channel blockers and potassium channel blockers. Atrial fibrillation increases the risk of stroke due to atrial thrombus formation and embolization. Anticoagulation with the vitamin K antagonist, warfarin, remains the most widely prescribed treatment option to decrease stroke risk. Several other antithrombotic agents have recently become available and offer excellent alternatives to warfarin. Catheter ablation can be undertaken as a nonpharmacologic rhythm control option with varying degrees of success depending on duration of atrial fibrillation and follow-up time from the procedure. This review article further describes the management options for patients presenting with atrial fibrillation.

Potential use of NOACs in developing countries: pros and cons

PURPOSE

Although vitamin K antagonists (VKAs) are effective for long-term thromboprophylaxis in atrial fibrillation (AF), their limitations have led to widespread underutilisation, especially in the developing world. Novel oral anticoagulants (NOACs) have emerged as promising alternatives to VKAs, although there are some particular considerations and challenges to their introduction in developing countries. This review summarises the current state of antithrombotic management of AF in the developing world, explores the early evidence for the NOACs and describes some of the special considerations that must be taken into account when considering the role of the NOACs within developing countries' health care systems.

METHODS

A literature search was conducted via PubMed and Google Scholar to find articles published in English between the years 2000 to 2014. Search terms used were "atrial fibrillation", "oral anticoagulants", "warfarin", "NOACs", "dabigatran", "rivaroxaban", "apixaban", "edoxaban", "time in therapeutic range", "International Normalized Ratio" "cost-effectiveness", "stroke", "adverse-drug reactions" and "drug-drug interactions", together with the individual names of developing countries as listed by the World Bank. We reviewed the results of randomized clinical trials, relevant retrospective and prospective studies, case-studies and review articles.

RESULTS

Many developing countries lack or have sporadic data on the quality of AF management, making it difficult to anticipate the potential impact of NOACs in these settings. The utilisation of anticoagulants for AF appears highly variable in developing countries. Given the issues associated with VKA therapy in many developing countries, NOACs offer some potential advantages; however, there is insufficient evidence to advocate the widespread replacement of warfarin at present. VKAs may continue to have a role in selected patients or countries, especially if alternative monitoring strategies can be utilised.

CONCLUSION

The evaluation of the introduction of NOACs should consider safety, budget concerns and the quality of oral anticoagulation care achieved by each country. Prospective registries will be important in developing countries to better elucidate the comparative safety, efficacy and cost-effectiveness of NOACs and VKAs as NOACs are introduced into practice.

Stroke prevention in atrial fibrillation: Commentary regarding the AAN's evidence-based guideline update

Atrial fibrillation is a common, potentially preventable cause of disabling stroke in the elderly, particularly in elderly women, resulting from embolism of stasis-precipitated thrombi formed in the left atrial appendage. In 1989, the first randomized clinical trial of anticoagulant therapy in atrial fibrillation showed that warfarin produced a large reduction in ischemic stroke.¹ In the ensuing 25 years, more than 40 additional randomized trials have permitted stroke prophylaxis to be importantly refined. It has been a period of remarkable progress in stroke prevention. Here, we discuss selected aspects of the American Academy of Neurology (AAN)'s evidence-based guideline update.^2.

The Potential Role of Edoxaban in Stroke Prevention Guidelines

With the emergence of edoxaban, the oral factor Xa inhibitors now appear consolidated as the dominant class of novel oral anticoagulants (NOACs) for stroke prevention in non-valvular atrial fibrillation (AF). The oral factor Xa inhibitors do not require an adequate time in therapeutic range to be effective, presenting a potential advantage over the vitamin K antagonists (VKAs). Guidelines are changing to reflect the increased choice of anticoagulants and as clinicians move away from the VKAs towards the relative safety and efficacy of NOACs, they must consider which one offers the best therapy for their patient. The ENGAGE-AF study was the latest phase III trial to report on the safety and efficacy of a new factor Xa inhibitor relative to warfarin. Both edoxaban 60mg once daily, and edoxaban 30mg once daily were found to be non-inferior compared to warfarin for the prevention of ischaemic stroke and systemic embolism, being associated with significantly lower rates of major bleeding, intracranial haemorrhage and cardiovascular death. A two-tiered dosing option may present clinicians with a further element of choice for the individual patient.

Rivaroxaban for stroke prevention in East Asian patients from the ROCKET AF trial

BACKGROUND AND PURPOSE

In Rivaroxaban Once Daily Oral Direct Factor Xa Inhibitor Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) trial, rivaroxaban was noninferior to dose-adjusted warfarin in preventing stroke or systemic embolism among patients with nonvalvular atrial fibrillation at moderate to high stroke risk. Because of differences in patient demographics, epidemiology, and stroke risk management in East Asia, outcomes and relative effects of rivaroxaban versus warfarin were assessed to determine consistency among East Asians versus other ROCKET AF participants.

METHODS

Baseline demographics and interaction of treatment effects of rivaroxaban and warfarin among patients within East Asia and outside were assessed.

RESULTS

A total of 932 (6.5%) ROCKET AF participants resided in East Asia. At baseline, East Asians had lower weight, creatinine clearance, and prior vitamin K antagonist use; higher prevalence of prior stroke; and less congestive heart failure and prior myocardial infarction than other participants. Despite higher absolute event rates for efficacy and safety outcomes in East Asians, the relative efficacy of rivaroxaban (20 mg once daily; 15 mg once daily for creatinine clearance of 30-49 mL/min) versus warfarin with respect to the primary efficacy end point (stroke/systemic embolism) was consistent among East Asians and non-East Asians (interaction P=0.666). Relative event rates for the major or nonmajor clinically relevant bleeding in patients treated with rivaroxaban and warfarin were consistent among East Asians and non-East Asians (interaction P=0.867).

CONCLUSIONS

Observed relative efficacy and safety of rivaroxaban versus warfarin were similar among patients within and outside East Asia. Rivaroxaban, 20 mg once daily, is an alternative to warfarin for stroke prevention in East Asians with nonvalvular atrial fibrillation.

Bleeding risk and mortality of edoxaban: a pooled meta-analysis of randomized controlled trials

OBJECTIVE(S)

Edoxaban, a factor Xa inhibitor, is a new oral anticoagulant that has been developed as an alternative to vitamin K antagonists. However, its safety remains unexplored.

METHODS

Medline, Embase and Web of Science were searched to March 8, 2014 for prospective, randomized controlled trials (RCTs) that assessed the safety profile of edoxaban with warfarin. Safety outcomes examined included bleeding risk and mortality.

RESULTS

Five trials including 31,262 patients that met the inclusion criteria were pooled. Overall, edoxaban was associated with a significant decrease in major or clinically relevant nonmajor bleeding events [risk ratio (RR) 0.78, 95% confidence interval (CI) 0.74 to 0.82, p<0.001] and any bleeding events [RR 0.82, 95% CI 0.79 to 0.85, p<0.001]. Edoxaban also showed superiority to warfarin both in all-cause mortality [RR 0.92, 95% CI 0.85 to 0.99, p = 0.02] and cardiovascular mortality [RR 0.87, 95% CI 0.79 to 0.96, p = 0.004]. Subgroup analyses indicated that RRs of edoxaban 30, 60 or 120 mg/d were 0.67 (p<0.001), 0.87 (p<0.001) and 3.3 (p = 0.004) respectively in major or clinically relevant nonmajor bleeding; 0.71 (p<0.001), 0.89 (p<0.001) and 2.29 (p = 0.002) respectively in any bleeding; as well as 0.86 (p = 0.01), 0.87 (p = 0.01) and 0.28 (p = 0.41) respectively in cardiovascular death… Meanwhile, paramount to note that pooled results other than the largest trial showed edoxaban was still associated with a decrease in the rate of major or clinically relevant nonmajor bleeding event (p = 0.02) and any bleeding (p = 0.002), but neither in all-cause death (p = 0.66) nor cardiovascular death (p = 0.70).

CONCLUSIONS

Edoxaban, a novel orally available direct factor Xa inhibitor, seems to have a favorable safety profiles with respect to bleeding risk and non-inferior in mortality when compared to warfarin. Further prospective RCTs are urgently needed to confirm the results of this meta-analysis.

Anticoagulation in atrial fibrillation

Atrial fibrillation increases the risk of stroke, which is a leading cause of death and disability worldwide. The use of oral anticoagulation in patients with atrial fibrillation at moderate or high risk of stroke, estimated by established criteria, improves outcomes. However, to ensure that the benefits exceed the risks of bleeding, appropriate patient selection is essential. Vitamin K antagonism has been the mainstay of treatment; however, newer drugs with novel mechanisms are also available. These novel oral anticoagulants (direct thrombin inhibitors and factor Xa inhibitors) obviate many of warfarin's shortcomings, and they have demonstrated safety and efficacy in large randomized trials of patients with non-valvular atrial fibrillation. However, the management of patients taking warfarin or novel agents remains a clinical challenge. There are several important considerations when selecting anticoagulant therapy for patients with atrial fibrillation. This review will discuss the rationale for anticoagulation in patients with atrial fibrillation; risk stratification for treatment; available agents; the appropriate implementation of these agents; and additional, specific clinical considerations for treatment.

Left Atrial Appendage Closure with Transcatheter-Delivered Devices

Left atrial appendage (LAA) closure with transcatheter-delivered devices is an evolving story of compelling randomized data and the potential to dramatically reduce the incidence of stroke and improve the quality of life among patients with atrial fibrillation. Oral anticoagulation is the standard of care for stroke prevention in atrial fibrillation but falls short of providing an adequate solution to this common threat when considered from efficacy and safety perspectives. The robust series of Watchman device trials has demonstrated the Watchman device to provide stroke prevention efficacy similar to that of warfarin and by extension provides proof of concept of LAA closure.

Comparison of the phase III clinical trial designs of novel oral anticoagulants versus warfarin for the treatment of nonvalvular atrial fibrillation: implications for clinical practice

Although vitamin K antagonists (VKAs) have been the backbone of thromboprophylaxis in nonvalvular atrial fibrillation, their limitations have encouraged the development of a new generation of oral anticoagulants. This review compares the different designs and procedures used to conduct four phase III trials that tested dabigatran, rivaroxaban, apixaban, and edoxaban versus VKAs. Although pharmacologic characteristics and results of the main trials are briefly discussed, this review mainly focuses on study designs, enrollment criteria, populations studied, quality metrics, and transition strategies between oral anticoagulants. While each of the trials was of high quality, performed independently, and led by independent academic groups, substantial differences exist in terms of drug pharmacology and trial characteristics. Caution is advised when comparing results across trials as practicing clinicians strive to personalize anticoagulation treatments for their individual patients. We believe that the differences in the pharmacokinetic and pharmacodynamic profiles of the available novel oral anticoagulants (NOACs), coupled with substantial heterogeneity in the trial populations and designs and procedures used to conduct the trials, support an important role for each of the NOACs dependent upon the specific clinical scenario faced by the practicing clinician.

Management of atrial fibrillation

Atrial fibrillation (AF) is associated with increases in the risk of mortality, congestive heart failure, and stroke. Medical treatment is aimed at preventing thrombo-embolic complications and reducing symptoms and consequences related to the arrhythmia. In the first section of this review, we discuss the principles of mainstream oral anticoagulant therapy and the possible advantages of the new oral anticoagulants. In the second section, we review the catheter ablation approaches to paroxysmal and persistent/long-standing AF, their results, and the current application of new catheters.

Comparison of the efficacy and safety of new oral anticoagulants with warfarin in patients with atrial fibrillation: a meta-analysis of randomised trials

BACKGROUND

Four new oral anticoagulants compare favourably with warfarin for stroke prevention in patients with atrial fibrillation; however, the balance between efficacy and safety in subgroups needs better definition. We aimed to assess the relative benefit of new oral anticoagulants in key subgroups, and the effects on important secondary outcomes.

METHODS

We searched Medline from Jan 1, 2009, to Nov 19, 2013, limiting searches to phase 3, randomised trials of patients with atrial fibrillation who were randomised to receive new oral anticoagulants or warfarin, and trials in which both efficacy and safety outcomes were reported. We did a prespecified meta-analysis of all 71,683 participants included in the RE-LY, ROCKET AF, ARISTOTLE, and ENGAGE AF-TIMI 48 trials. The main outcomes were stroke and systemic embolic events, ischaemic stroke, haemorrhagic stroke, all-cause mortality, myocardial infarction, major bleeding, intracranial haemorrhage, and gastrointestinal bleeding. We calculated relative risks (RRs) and 95% CIs for each outcome. We did subgroup analyses to assess whether differences in patient and trial characteristics affected outcomes. We used a random-effects model to compare pooled outcomes and tested for heterogeneity.

FINDINGS

42,411 participants received a new oral anticoagulant and 29,272 participants received warfarin. New oral anticoagulants significantly reduced stroke or systemic embolic events by 19% compared with warfarin (RR 0·81, 95% CI 0·73-0·91; p<0·0001), mainly driven by a reduction in haemorrhagic stroke (0·49, 0·38-0·64; p<0·0001). New oral anticoagulants also significantly reduced all-cause mortality (0·90, 0·85-0·95; p=0·0003) and intracranial haemorrhage (0·48, 0·39-0·59; p<0·0001), but increased gastrointestinal bleeding (1·25, 1·01-1·55; p=0·04). We noted no heterogeneity for stroke or systemic embolic events in important subgroups, but there was a greater relative reduction in major bleeding with new oral anticoagulants when the centre-based time in therapeutic range was less than 66% than when it was 66% or more (0·69, 0·59-0·81 vs 0·93, 0·76-1·13; p for interaction 0·022). Low-dose new oral anticoagulant regimens showed similar overall reductions in stroke or systemic embolic events to warfarin (1·03, 0·84-1·27; p=0·74), and a more favourable bleeding profile (0·65, 0·43-1·00; p=0·05), but significantly more ischaemic strokes (1·28, 1·02-1·60; p=0·045).

INTERPRETATION

This meta-analysis is the first to include data for all four new oral anticoagulants studied in the pivotal phase 3 clinical trials for stroke prevention or systemic embolic events in patients with atrial fibrillation. New oral anticoagulants had a favourable risk-benefit profile, with significant reductions in stroke, intracranial haemorrhage, and mortality, and with similar major bleeding as for warfarin, but increased gastrointestinal bleeding. The relative efficacy and safety of new oral anticoagulants was consistent across a wide range of patients. Our findings offer clinicians a more comprehensive picture of the new oral anticoagulants as a therapeutic option to reduce the risk of stroke in this patient population.

FUNDING

None.