Nonvitamin K Anticoagulant Agents in Patients With Advanced Chronic Kidney Disease or on Dialysis With AF

Risks and Benefits of Direct Oral Anticoagulants across the Spectrum of GFR among Incident and Prevalent Patients with Atrial Fibrillation

BACKGROUND AND OBJECTIVES

All randomized trials of direct oral anticoagulants in atrial fibrillation excluded patients with severe kidney disease. The safety and effectiveness of direct oral anticoagulants across the range of eGFR in real-world settings is unknown. Our objective is to quantify the risk of bleeding and benefit of ischemic stroke prevention for direct oral anticoagulants compared with warfarin in patients with atrial fibrillation with and without CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We created a propensity score-matched cohort of 3206 patients with atrial fibrillation and direct oral anticoagulant use and 3206 patients with atrial fibrillation using warfarin from October of 2010 to February of 2017 in an electronic health record (Geisinger Health System). The risks of bleeding and ischemic stroke were compared between direct oral anticoagulant and warfarin users using Cox proportional hazards regression, stratified by eGFR (≥60 and <60 ml/min per 1.73 m2).

RESULTS

The mean (SD) age of the 6412 participants was 72 (12) years, 47% were women, and average eGFR was 69 (21) ml/min per 1.73 m2. There were 1181 bleeding events and 466 ischemic strokes over 7391 person-years of follow-up. Compared with warfarin use, the hazard ratios (HRs) (95% confidence interval [95% CI]) of bleeding associated with direct oral anticoagulant use were 1.01 (0.88 to 1.17) and 1.23 (1.02 to 1.48) for those with eGFR≥60 and eGFR<60 ml/min per 1.73 m2, respectively (P-interaction=0.10). There was no difference between direct oral anticoagulant and warfarin users in the risk of ischemic stroke: HRs (95% CI) of 0.94 (0.74 to 1.18) and 1.02 (0.76 to 1.37) for those with eGFR≥60 and eGFR<60 ml/min per 1.73 m2, respectively (P-interaction=0.70). Similar findings were observed with individual drugs.

CONCLUSIONS

In a large health care system, patients with eGFR<60 ml/min per 1.73 m2 who took direct oral anticoagulants for atrial fibrillation had slightly higher risk of bleeding compared with those on warfarin, but similar benefits from prevention of ischemic stroke.

Nonvitamin K Oral Anticoagulants in Patients With Atrial Fibrillation and Severe Renal Dysfunction

Both atrial fibrillation (AF) and chronic kidney disease (CKD) are highly prevalent, especially with increasing age and associated comorbidities, such as hypertension, diabetes, heart failure, and vascular disease. The relationship between both AF and CKD seems to be bidirectional: CKD predisposes to AF while onset of AF seems to lead to progression of CKD. Stroke prevention is the cornerstone of AF management, and AF patients with CKD are at higher risk of stroke, mortality, cardiac events, and bleeding. Stroke prevention requires use of oral anticoagulants, which are either vitamin K antagonists (eg, warfarin), or the nonvitamin K antagonist oral anticoagulants (NOACs). While NOACs have been shown to be effective in mild-to-moderate renal dysfunction, there are a paucity of data regarding NOACs in severe and end-stage renal dysfunction. This review first discusses the evidence for NOACs in CKD. Second, we summarize the current knowledge regarding the efficacy and safety of NOACs to prevent AF-related stroke and systemic embolism in severe and end-stage renal disease.

Deleting Death and Dialysis: Conservative Care of Cardio-Vascular Risk and Kidney Function Loss in Chronic Kidney Disease (CKD)

The uremic syndrome, which is the clinical expression of chronic kidney disease (CKD), is a complex amalgam of accelerated aging and organ dysfunctions, whereby cardio-vascular disease plays a capital role. In this narrative review, we offer a summary of the current conservative (medical) treatment options for cardio-vascular and overall morbidity and mortality risk in CKD. Since the progression of CKD is also associated with a higher cardio-vascular risk, we summarize the interventions that may prevent the progression of CKD as well. We pay attention to established therapies, as well as to novel promising options. Approaches that have been considered are not limited to pharmacological approaches but take into account lifestyle measures and diet as well. We took as many randomized controlled hard endpoint outcome trials as possible into account, although observational studies and post hoc analyses were included where appropriate. We also considered health economic aspects. Based on this information, we constructed comprehensive tables summarizing the available therapeutic options and the number and kind of studies (controlled or not, contradictory outcomes or not) with regard to each approach. Our review underscores the scarcity of well-designed large controlled trials in CKD. Nevertheless, based on the controlled and observational data, a therapeutic algorithm can be developed for this complex and multifactorial condition. It is likely that interventions should be aimed at targeting several modifiable factors simultaneously.

Safety and effectiveness of rivaroxaban and warfarin in moderate-to-advanced CKD: real world data

BACKGROUND

In recent years, novel anticoagulant drugs have been introduced in the clinical armamentarium and have progressively gained momentum. Although their use is increasing among CKD patients, some skepticism about their risk-benefit ratio still persists. We sought to investigate the safety and effectiveness of rivaroxaban in a cohort of moderate-to-advanced CKD patients.

METHODS

This observational, retrospective, longitudinal study involved 347 consecutive CKD stage 3b-4 (according to NKF-KDOQI guidelines) patients enrolled from 8 cardiac outpatient clinics between March 2015 and October 2017. All patients received anticoagulation (100 warfarin vs. 247 rivaroxaban) as part of their non-valvular atrial fibrillation management at the attending physician's discretion. Clinical effectiveness (defined as the occurrence of ischemic stroke, venous thromboembolism, or transient ischemic attack) and safety (intracranial hemorrhage, gastrointestinal or other bleeding) were assessed separately.

RESULTS

Over a mean follow-up period of 16 ± 0.3 months, 25 stroke episodes (15 hemorrhagic, and 10 ischemic) occurred in 24 warfarin treated patients vs. none in the rivaroxaban arm. There were 5 vs. 0 episodes of deep venous thrombosis and 8 vs. 2 major episodes of bleeding in the warfarin and rivaroxaban groups, respectively. In contrast, the proportion of minor episodes of bleeding was similar between groups.

CONCLUSION

Rivaroxaban seems a safe and effective therapeutic option in CKD stage 3b-4 patients. However, future randomized controlled trials are needed to definitively establish the role of rivaroxaban in CKD patients.

Safety and Efficacy of Apixaban Versus Warfarin in Patients With Advanced Chronic Kidney Disease

Background: Because of a lack of comparative data on anticoagulant use in the advanced chronic kidney disease (CKD) population, guidelines recommend warfarin for atrial fibrillation and venous thromboembolism (VTE) treatment in these patients. However, apixaban has specific dosing recommendations in CKD leading to use in clinical practice. Objective: To evaluate major bleeding, stroke, and thromboembolism rates in patients with CKD stage 4, stage 5, and dialysis on apixaban or warfarin therapy. Methods: This was a retrospective cohort study of patients with advanced CKD receiving apixaban or warfarin. The primary outcome was the occurrence of major bleeding at 3 months after enrollment. Secondary outcomes included occurrence of major bleeding, occurrence of ischemic stroke, and recurrence of VTE at 3 to 6 and 6 to 12 months. Results: A total of 604 patients were included in the analysis. The percentage of apixaban and warfarin patients with a major bleed at 0 to 3, 3 to 6, and 6 to 12 months were 8.3% versus 9.9% ( P=0.48), 1.4% versus 4% ( P=0.07), and 1.5% versus 8.4% ( P<0.001), respectively. There were no differences in rates of ischemic stroke or recurrent VTE at any time period. Conclusion and Relevance: Patients with advanced CKD taking apixaban had similar bleeding rates at 3 months compared with those taking warfarin. However, those who continued therapy had higher major bleeding rates with warfarin between 6 and 12 months. This study provides knowledge on the effects of a direct oral anticoagulant in a population that was excluded from all major trials.

Non-Vitamin K-Dependent Oral Anticoagulants for Nonvalvular Atrial Fibrillation in Patients With CKD: Pragmatic Considerations for the Clinician

Management of atrial fibrillation (AF) in patients with advanced chronic kidney disease (CKD) poses a complex conundrum because of higher risks for both thromboembolic and bleeding complications compared to the general population. This makes it particularly important for clinicians to carefully weigh the risks versus benefits of anticoagulation therapy to determine the individualized net clinical benefit for every patient. During the past few years, 4 non-vitamin K-dependent oral anticoagulant (NOAC) agents have supplemented warfarin in the therapeutic armamentarium for the prevention of systemic thromboembolism in nonvalvular AF. However, the use of NOACs in CKD specifically mandates a nuanced understanding due to their varying dependence on renal clearance, with resultant safety implications related to either underdosing (thromboembolism) or excessive drug exposure (bleeding). This pragmatic review highlights unique considerations pertaining to accurate estimation and temporal monitoring of kidney function in the context of NOAC use with specific clinical deliberations and variables when determining whether an NOAC is appropriate for a patient with CKD. The dependence of NOACs on renal clearance and several troubling safety signals in the published literature suggest that it is vital for nephrologists to be active members of a multidisciplinary team caring for these high-risk patients with CKD and AF.

Oral Anticoagulation in Chronic Kidney Disease and Atrial Fibrillation

BACKGROUND

Cardiological societies recommend, in their guidelines, that patients with atrial fibrillation and an intermediate (or higher) risk of stroke and systemic embolization should be treated with oral anticoagulant drugs. For patients who do not have mitral valve stenosis or a mechanical valve prosthesis, non-vitamin-K dependent oral anticoagulants (NOAC) are preferred over vitamin K antagonists (VKA) for this purpose. It is unclear, however, whether patients with chronic kidney disease and atrial fibrillation benefit from oral anticoagulation to the same extent as those with normal kidney function. It is also unclear which of the two types of anti - coagulant drug is preferable for patients with chronic kidney disease; NOAC are, in part, renally eliminated.

METHODS

This review is based on pertinent publications retrieved by a selective literature search, and on international guidelines.

RESULTS

Current evidence suggests that patients with atrial fibrillation who have chronic kidney disease with a glomerular filtration rate (GFR) above 15 mL/ min/1.73 m² should be treated with an oral anticoagulant drug if they have an at least intermediate risk of embolization, as assessed with the CHA2DS2-VASc score. For patients with advanced chronic kidney disease (GFR from 15 to 29 mL/ min/1.73 m²), however, this recommendation is based only on registry studies. For dialysis patients with atrial fibrillation, decisions whether to give oral anticoagulant drugs should be taken on an individual basis, in view of the elevated risk of hemorrhage and the unclear efficacy of such drugs in these patients. The subgroup analyses of the NOAC approval studies show that, for patients with atrial fibrillation and chronic kidney disease with a creatinine clearance of >25-30 mL/min, NOAC should be given in preference to VKA, as long as the patient does not have mitral valve stenosis or a mechanical valve prosthesis. For those whose creatinine clearance is less than 25 mL/min, the relative merits of NOAC versus VKA are still debated.

CONCLUSION

The cardiological societies' recommendation that patients with atrial fibrillation should be given oral anticoagulant drugs applies to the majority of such patients who also have chronic kidney disease.

[Anticoagulation in patients with chronic kidney disease : Recommendations from the working group "Heart-Kidney" of the German Cardiac Society and the German Society of Nephrology]

Indications for anticoagulation are thromboembolic events, prosthetic heart valves, and atrial fibrillation with a corresponding risk score. Clinical trials have excluded patients with advanced chronic kidney disease and these data cannot be always generalized to patients with chronic kidney disease. Non-vitamin K antagonist oral anticoagulants (NOACs) are mostly not recommended or are contraindicated in advanced stages of chronic kidney disease. Observational studies have shown that dialysis patients with atrial fibrillation do not profit from coumarin anticoagulants; prospective studies are lacking.

Is anticoagulating haemodialysis patients with non-valvular atrial fibrillation too risky?

There is an increasing understanding of the risks from atrial fibrillation (AF) in the current era. In patients with end-stage renal disease (ESRD) on dialysis, the prevalence of AF is significantly higher compared to the general population and those with earlier stages of CKD. Although anticoagulation of these patients may seem appropriate, there is a lack of conclusive evidence that it provides the same protection from thromboembolic complications as it does in patients not on dialysis. In addition, the increased risk of bleeding in patients requiring dialysis makes the use of anticoagulants less favourable. This article aims to discuss the problem of AF in dialysis patients, summarise the current evidence around the use of oral anticoagulants for AF in ESRD and provide some practical suggestions on management of AF in the haemodialysis population.

Non-Vitamin K Antagonist Oral Anticoagulants in Patients With Atrial Fibrillation and End-Stage Renal Disease

Over the past decade, there have been tremendous advancements in anticoagulation therapies for stroke prevention in patients with atrial fibrillation (AF). Although the non-vitamin K antagonist oral anticoagulants (NOACs) demonstrated favorable clinical outcomes compared with warfarin overall, the decision to anticoagulate and the choice of appropriate agent in patients with AF and concomitant chronic kidney disease (CKD) or end-stage renal disease (ESRD) are a particularly complex issue. CKD and ESRD increase both the risk of stroke and bleeding, and since all of the NOACs undergo various levels of renal clearance, renal dysfunction inevitably affects the pharmacokinetics of the drug in each patient. Furthermore, the randomized controlled clinical trials of each NOAC versus warfarin often did not include patients with advanced CKD or ESRD. In this focused review, we describe the available evidence supporting the use of NOACs for prevention of stroke in patients with AF with concomitant advanced CKD or ESRD. Although questions of safety and appropriate use of these new agents in CKD and ESRD remain, NOACs offer a significant step forward in the anticoagulation management of at-risk patients with AF.

DOAC use in patients with chronic kidney disease

Direct oral anticoagulants (DOACs) are increasingly prescribed substances in patients with indication for effective anticoagulation. Patients with chronic kidney disease (CKD) have a high burden of cardiovascular risk and are more likely to develop atrial fibrillation (AF) than patients without CKD. Patients with mild to moderate CKD benefit from DOACs, especially when having intolerance to vitamin K-antagonists (VKA). DOACs may in some cases be considered in patients with rare renal disease and hypercoagulabilic state. DOACs are to a large extent eliminated by renal excretion. Since prospective randomised data in CKD patients are sparse, the decision for anticoagulative therapy is challenging especially in patients with severe renal impairment. The direct factor Xa-inhibitors are approved for use even in patients with an estimated glomerular filtration rate (eGFR) between 15 and 30 ml/min. Careful monitoring of renal function on a regular basis is essential before initiation and after start of DOAC, especially for patients at risk for acute renal failure (elderly, diabetics, patients with preexisting kidney disease). None of the DOACs is approved in CKD patients with end-stage-renal-disease (ESRD) with or without dialysis. DOACs are not recommended for kidney transplant patients under immunosuppression with calcineurin inhibitors. In these patients conventional therapy with VKA is the only option, which has to be monitored closely since it has potential adverse effects.

Drug Class, Renal Elimination, and Outcomes of Direct Oral Anticoagulants in Asian Patients: A Meta-Analysis

BACKGROUND

Direct oral anticoagulants (DOACs) have a better risk benefit profile in Asian patients with atrial fibrillation (AF). Whether treatment effects could be modified by drug class and dependency on renal elimination of studied agents has not yet been explored.

METHODS

We searched PubMed, CENTRAL, and CINAHL databases through November 2016 for phase III randomized controlled trials comparing DOACs with warfarin in patients with AF. Efficacy and safety outcomes were pooled according to drug class and dependency on renal elimination of DOACs and were compared with the Mantel-Haenszel fixed-effects model. Effect differences were assessed with Bucher's indirect comparisons using common estimates, once heterogeneity was low, and with the Bayesian method.

RESULTS

Among 6496 Asian patients from 6 trials, both direct thrombin inhibitors and factor Xa inhibitors, compared with warfarin, were associated with lower risks of stroke or systemic embolism and major bleeding (risk ratio [95% confidence interval], 0.51 [0.33-0.78], 0.74 ([0.58-0.96], 0.60 [0.41-0.86], and 0.59 [0.47-0.76], respectively). There was no between-group difference in direct thrombin inhibitors and factor Xa inhibitors or in DOACs with renal elimination less than 50% and 50% or greater (all I² < 25% and interaction P > .05). Indirect comparisons within strata of drug class and dependency on renal elimination showed no preferential effect of any given regimen over another. There was no difference in effects on ischemic and hemorrhagic stroke, intracranial hemorrhage, myocardial infarction, and all-cause mortality between DOACs stratified by pharmacologic characteristics.

CONCLUSIONS

DOACs, as a therapeutic class, outperform warfarin in efficacy and safety in Asian patients with AF.

Pharmacokinetics of Tecarfarin and Warfarin in Patients with Severe Chronic Kidney Disease

Chronic kidney disease (CKD) complicates warfarin anticoagulation partially through its effect on CYP2C9 activity. Tecarfarin, a novel vitamin K antagonist, is not metabolized by CYP2C9. To evaluate the effect of CKD on their metabolism, we measured PK parameters of warfarin and tecarfarin in subjects with and without CKD. CKD subjects with estimated glomerular filtration rate < 30 mL/min not on dialysis (n = 13) were matched to healthy volunteers (HVs) (n = 10). Each subject was randomized to either warfarin 10 mg or tecarfarin 30 mg and was later crossed over to the other drug. PK parameters were measured following each drug. Mean plasma concentrations of (S)-warfarin and (R,S)-warfarin were higher (44 and 27%, respectively) in the subjects with CKD than in the healthy subjects. Both of these values fell outside of the 90% confidence interval of equivalence. For tecarfarin, the difference was less than 15% higher. Elimination half-life (t_1/2) increased by 20% for (S)-warfarin and by 8% for (R,S)-warfarin and decreased by 8% for tecarfarin. The mean plasma concentration for tecarfarin's inactive metabolite ATI-5900 increased by approximately eightfold. CKD increased the effect of CYP2C9 genetic variation on (S)-warfarin and (R,S)-warfarin metabolism. Tecarfarin exposure was similar between the HVs and the CKD subjects regardless of CYP2C9 genotype. There were neither serious adverse events (SAEs) nor treatment-emergent adverse events (TEAEs) for any subject in the study. CKD inhibits metabolism of (S)-warfarin and (R,S)-warfarin, but not tecarfarin. The safety of repeated dosing of tecarfarin in CKD patients remains unknown. However, if the PK findings of this single-dose study are present with repeated dosing, tecarfarin may lead to dosing that is more predictable than warfarin in CKD patients who require anticoagulation therapy.

Percutaneous closure of the left atrial appendage in patients with diabetes mellitus

BACKGROUND

Left atrial appendage closure is a preventive treatment of atrial fibrillation-related thrombo-embolism. Patients with diabetes mellitus have increased risk for a negative outcome in percutaneous cardiac interventions. We assessed whether percutaneous left atrial appendage closure is safe and effective in patients with diabetes mellitus.

METHODS

We included 78 patients (mean age of 74.4 ± 8.3 years) with indication for left atrial appendage closure in an open-label observational single-centre study.

RESULTS

Patients with diabetes mellitus ( n = 31) were at higher thrombo-embolic and bleeding risk (CHA₂DS₂-VASc: 4.5 ± 0.9, HAS-BLED: 4.7 ± 0.7) compared to patients without diabetes mellitus ( n = 47, CHA₂DS₂-VASc: 3.5 ± 1.0, HAS-BLED: 4.1 ± 0.8; p < 0.001 for both). Pre- and periprocedural risk was elevated in patients with diabetes mellitus (Euro II-Score: 6.6 ± 3.7 vs 3.9 ± 1.9, p < 0.01; Society of Thoracic Surgeons (STS)-Score: 4.0 ± 2.5 vs 2.6 ± 1.2, p < 0.01). Procedural success was similar. Periprocedural major adverse cardiac and cerebrovascular events occurred in one patient from the control group (2.1%), whereas patients with diabetes mellitus had no events ( p = 0.672). Follow-up of 6 months revealed no bleeding complication in both groups. No stroke occurred in follow-up, and left atrial appendage flow velocity reduction (55.6 ± 38.6 vs 51.4 ± 19.1 cm/s, p = 0.474) and rate of postinterventional leakage in the left atrial appendage were comparable (0% vs 2.1%, p = 0.672).

CONCLUSION

Despite patients with diabetes mellitus are high-risk patients, the outcome of percutaneous left atrial appendage closure is similar to patients without diabetes mellitus.

Editor-in-Chief's Top Picks From 2016: Part Two

Each week, I record audio summaries for every article in JACC, as well as an issue summary. While this process has been incredibly time-consuming, I have become quite familiar with every paper that we publish. Thus, I personally select papers (both original investigations and review articles) from 15 distinct specialties each year for your review. In addition to my personal choices, I have included manuscripts that have been the most accessed or downloaded on our websites, as well as those selected by the JACC Editorial Board members. In order to present the full breadth of this important research in a consumable fashion, we will present these manuscripts in this issue of JACC. Part One included the sections: Basic & Translational Research, Cardiac Failure, Cardiomyopathies/Myocardial & Pericardial Diseases, Congenital Heart Disease, Coronary Disease & Interventions, and CVD Prevention & Health Promotion. Part Two includes the sections: CV Medicine & Society, Hypertension, Imaging, Metabolic & Lipid Disorders, Rhythm Disorders, Valvular Heart Disease, and Vascular Medicine (1-84).

2017 consensus of the Asia Pacific Heart Rhythm Society on stroke prevention in atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia, causing a 2-fold increase in mortality and a 5-fold increase in stroke. The Asian population is rapidly aging, and in 2050, the estimated population with AF will reach 72 million, of whom 2.9 million may suffer from AF-associated stroke. Therefore, stroke prevention in AF is an urgent issue in Asia. Many innovative advances in the management of AF-associated stroke have emerged recently, including new scoring systems for predicting stroke and bleeding risks, the development of non-vitamin K antagonist oral anticoagulants (NOACs), knowledge of their special benefits in Asians, and new techniques. The Asia Pacific Heart Rhythm Society (APHRS) aimed to update the available information, and appointed the Practice Guideline sub-committee to write a consensus statement regarding stroke prevention in AF. The Practice Guidelines sub-committee members comprehensively reviewed updated information on stroke prevention in AF, emphasizing data on NOACs from the Asia Pacific region, and summarized them in this 2017 Consensus of the Asia Pacific Heart Rhythm Society on Stroke Prevention in AF. This consensus includes details of the updated recommendations, along with their background and rationale, focusing on data from the Asia Pacific region. We hope this consensus can be a practical tool for cardiologists, neurologists, geriatricians, and general practitioners in this region. We fully realize that there are gaps, unaddressed questions, and many areas of uncertainty and debate in the current knowledge of AF, and the physician׳s decision remains the most important factor in the management of AF.

A Multicenter Analysis of Factors Associated With Apixaban-Related Bleeding in Hospitalized Patients With End-Stage Renal Disease on Hemodialysis

BACKGROUND

In 2014, the United States Food and Drug Administration approved a labeling change for apixaban to include recommendations for patients with severe renal impairment and patients with end-stage renal disease (ESRD) on hemodialysis (HD), though these recommendations are largely based on pharmacokinetic and pharmacodynamic data.

OBJECTIVE

Identify variables associated with bleeding events in hospitalized patients with ESRD on HD receiving apixaban.

METHODS

This retrospective, multicenter cohort study evaluated hospitalized patients with ESRD on HD receiving apixaban from January 1, 2013, through March 31, 2016. Correlational analysis and logistic regression were completed to identify factors associated with bleeding.

RESULTS

A total of 114 adults were included in the analysis. The median length of stay (LOS) was 6.2 (interquartile range = 3.8-11.9) days and bleeding events occurred in a total of 17 patients (15%). A weak correlation was identified for higher cumulative apixaban exposure, increased number of HD sessions while receiving apixaban, and increased hospital LOS ( P < 0.05; correlation coefficient < 0.40). When controlling for confounders, logistic regression revealed that composite bleeding events were independently increased by continuation of outpatient apixaban (odds ratio = 13.07; 95% CI = 1.54-110.54; P = 0.018), increased total daily dose of apixaban (odds ratio = 1.72; 95% CI = 1.20 to 2.48; P = 0.003), and total HD sessions while receiving apixaban (odds ratio = 2.04; 95% CI = 1.06-3.92; P = 0.033).

CONCLUSION

The association between these factors and increased bleeding should prompt concern for long-term anticoagulation with apixaban in patients with ESRD receiving chronic HD.

Nonvitamin K-dependent oral anticoagulants (NOACs) in chronic kidney disease patients with atrial fibrillation

Atrial fibrillation (AF) represents the most common arrhythmia in patients with chronic kidney disease (CKD). As in the general population, in CKD patients AF is associated with an increased risk of thromboembolism and stroke. However, CKD patients, especially those on renal replacement therapy (RRT), also exhibit an increased risk of bleeding, especially from the gastrointestinal tract. Oral anticoagulation is the most effective form of thromboprophylaxis in patients with AF presenting increased risk of stroke. Limited evidence on efficacy, the increased risk of bleeding as well as some concern regarding the use of warfarin in CKD, has often resulted in the underuse of anticoagulation CKD patients. A large body of evidence suggests that non-vitamin K-dependent oral anticoagulant agents (NOACs) significantly reduce the risk of stroke, intracranial hemorrhage, and mortality, with lower to similar major bleeding rates compared with vitamin K antagonist such as warfarin in normal renal function subjects. Hence, they are currently recommended for patients with atrial fibrillation at risk for stroke. However, NOACs metabolism is largely dependent on the kidneys for elimination and little is known in patients with creatinine clearance <25ml/min who were excluded from all pivotal phase 3 NOACs trials. This review focuses on the current pharmacokinetic, observational, and prospective data on NOACs in patients with moderate to advanced chronic kidney disease (creatinine clearance 15-49ml/min) and those on dialysis.

Recent Advances in Stroke Prevention in Patients with Atrial Fibrillation and End-Stage Renal Disease

BACKGROUND

Chronic kidney disease (CKD) is associated with a high prevalence of atrial fibrillation (AF), but in this population the risk/benefit ratio of anticoagulant therapy with vitamin K antagonists (VKA) for thromboprophylaxis is uncertain.

SUMMARY

In end-stage renal disease (ESRD) patients undergoing hemodialysis, VKA seem less effective in stroke prevention than in the general population, with an increased risk of major bleeding. Recently, novel oral anticoagulant agents (NOACs) have proven to be effective for stroke prevention in AF and have demonstrated an improved safety profile compared to VKA. Limited data from post hoc analyses of controlled clinical trials suggest the safe and effective use of NOACs in patients with moderate renal impairment (i.e., estimated glomerular filtration rate, eGFR, between 30 and 50 mL/min). The question still remains whether NOACs can be used in patients with an eGFR <30 mL/min, since there are no studies addressing this subject. In fact, patients with CKD stage 4 and 5 were excluded from controlled clinical trials on anticoagulation therapy for stroke prevention in AF. Left atrial appendage (LAA) occlusion represents a nonpharmacological alternative for stroke prevention in patients with AF who are difficult to manage medically. Preliminary data indicate a similar efficacy and safety profile in patients with CKD compared to patients with normal renal function.

KEY MESSAGES

Stroke prevention in patients with ESRD and AF represents a clinical challenge with poor evidence. LAA occlusion may become the standard of care for stroke prevention in patients with ESRD and AF.

Emerging therapeutic uses of direct-acting oral anticoagulants: An evidence-based perspective

Direct-acting oral anticoagulants (DOACs) were claimed to cause a potential paradigm shift in the therapeutic scenario of patients requiring short- and long-term anticoagulation, by virtue of their pharmacological properties, perceived as innovative. The evidence gathered so far (from pre-approval pivotal trials to real-world post-marketing observational data) consistently confirmed that DOACs are overall comparable to vitamin-K antagonists (VKAs) in terms of safety, efficacy and effectiveness and unequivocally documented a consistent and clinically relevant reduced risk of intracranial bleeding in the settings of non-valvular atrial fibrillation (NVAF) and venous thromboembolism (VTE). Interestingly, two parallel paths can be identified in the current research scenario: A) in the aforementioned consolidated therapeutic indications, an innovative approach is directed towards tailored treatment strategies, to identify patients most likely to benefit from one of the different anticoagulant drugs, in particular subpopulations at increased risk of adverse events (e.g., bleeding); B) in unconventional settings, DOACs are gaining interest for potential use in emerging diseases characterized by arterial and venous thromboembolic risk. In these scenarios, the risk-benefit profile of DOACs, as compared to VKAs or heparins, is less defined. The aim of this review is to critically assess the body of evidence underlying emerging therapeutic uses of DOACs (e.g., heparin-induced thrombocytopenia, anti-phospholipid antibody syndrome), including evolving issues in special populations (e.g., patients with VTE and cancer or cirrhosis). This will be achieved by analyzing the strength (i.e., systematic reviews, randomized clinical trials, observational studies, case report/series) and consistency (i.e., concordance) of both published and unpublished evidence registered in major public repositories.

Cardiovascular Events in Hemodialysis Patients: Challenging against Vascular Calcification

Particularly in patients with hemodialysis, cardiovascular mortality rate is extremely high. Polyvascular diseases develop at an early stage of chronic kidney disease (CKD). Pathophysiology includes insulin resistance and/or imbalance between nitric oxide (NO) and endothelin bioavailability as well as oxidative stress. The understanding in pathophysiology of vascular calcification and strategic treatment is a critical issue to achieve favorable outcome for the patients with CKD. In this article, we aim to review the cardiovascular disease for the patients with CKD with a particular emphasis on the clinical aspects of polyvascular disease. Finally, we address to detect microcirculatory impairment and eradicate vascular calcification as early as possible prior to renal replacement therapy. (This is a translation of Jpn J Vasc Surg 2016; 25: 359-365.).

Apixaban Pharmacokinetics at Steady State in Hemodialysis Patients

It is unclear whether warfarin is protective or harmful in patients with ESRD and atrial fibrillation. This state of equipoise raises the question of whether alternative anticoagulants may have a therapeutic role. We aimed to determine apixaban pharmacokinetics at steady state in patients on hemodialysis. Seven patients received apixaban 2.5 mg twice daily for 8 days. Blood samples were collected before and after apixaban administration on days 1 and 8 (nondialysis days). Significant accumulation of the drug was observed between days 1 and 8 with the 2.5-mg dose. The area under the concentration-time curve from 0 to 24 hours increased from 628 to 2054 ng h/ml (P<0.001). Trough levels increased from 45 to 132 ng/ml (P<0.001). On day 9, after a 2.5-mg dose, apixaban levels were monitored hourly during dialysis. Only 4% of the drug was removed. After a 5-day washout period, five patients received 5 mg apixaban twice daily for 8 days. The area under the concentration-time curve further increased to 6045 ng h/ml (P=0.03), and trough levels increased to 218 ng/ml (P=0.03), above the 90th percentile for the 5-mg dose in patients with preserved renal function. Apixaban 2.5 mg twice daily in patients on hemodialysis resulted in drug exposure comparable with that of the standard dose (5 mg twice daily) in patients with preserved renal function and might be a reasonable alternative to warfarin for stroke prevention in patients on dialysis. Apixaban 5 mg twice daily led to supratherapeutic levels in patients on hemodialysis and should be avoided.

The Nonvitamin K Antagonist Oral Anticoagulants and Atrial Fibrillation: Challenges and Considerations

The nonvitamin K antagonist oral anticoagulants (NOACs) dabigatran, rivaroxaban, apixaban, and edoxaban are used for the reduction of the risk of stroke or systemic embolism (SEE) in patients with nonvalvular atrial fibrillation (NVAF). The purpose of this review is to highlight the safety and efficacy results of the pivotal NOAC clinical trials for use in NVAF, discuss some of the unique management challenges in the use of NOACs in special populations, summarize data on emerging and novel indications, and address potential future directions.

METHODS

A literature search was conducted and to identify relevant clinical trials and studies regarding the use of NOACs for the prevention of stroke or SEE in patients with atrial fibrillation.

RESULTS

Relative to warfarin, NOACs are as effective or superior in the prevention of stroke or SEE, and are associated with similar or lower rates of major bleeding and significantly decreased rates of intracranial bleeding, but may be associated with a slightly increased risk of gastrointestinal bleeding in patients with AF. The NOACs are not indicated for use and have not been widely tested in AF patients with other cardiovascular conditions. Additional ongoing and planned clinical trials will provide additional information regarding the use of NOACs in these patients. In situations requiring rapid reversal of anticoagulation, the availability of specific antidotes will improve safety and facilitate NOAC use.

CONCLUSIONS

Use of NOACs in clinical practice requires consideration of patient characteristics as well as potentially required procedures.

Defibrillation Testing During ICD Implantation - Should we or Should we Not?

The implantable cardioverter defibrillator (ICD) is an established therapy for improving mortality for primary and secondary prevention of sudden cardiac death. Whether to perform defibrillation threshold testing (DFT) either intraoperatively or post-operatively remains a controversial issue. The DFT is defined as the minimum energy required at which two shocks can successfully terminate ventricular fibrillation and dates from the era of surgically implanted devices with epicardial patches. Typically, a safety margin of at least 10J is employed for device programming, though some trial data suggest that a margin of 5J could be just as effective. Various methods have been utilized to perform DFT testing, and no particular method has been shown to be superior to another [Figure 1]. Previously, guideline recommendations addressed the indications for ICD implantation but did not comment on DFT testing. Recent consensus statements now provide some guidance as to when it is appropriate to perform or not perform DFT testing in light of new trial data. This review will address some of the risk factors for having a higher DFT, impact of DFT testing on patient outcomes, and some of the risks and contraindications of DFT testing.