Influence of kidney function on risk of supratherapeutic international normalized ratio-related hemorrhage in warfarin users: a prospective cohort study

Anticoagulation in Chronic Kidney Disease

The nuanced landscape of anticoagulation therapy in patients with chronic kidney disease (CKD) presents a formidable challenge, intricately balancing the dual hazards of hemorrhage and thrombosis. These patients find themselves in a precarious position, teetering on the edge of these risks due to compromised platelet functionality and systemic disturbances within their coagulation frameworks. The management of such patients necessitates a meticulous approach to dosing adjustments and vigilant monitoring to navigate the perilous waters of anticoagulant therapy. This is especially critical considering the altered pharmacokinetics in CKD, where the clearance of drugs is significantly impeded, heightening the risk of accumulation and adverse effects. In the evolving narrative of anticoagulation therapy, the introduction of direct oral anticoagulants (DOACs) has heralded a new era, offering a glimmer of hope for those navigating the complexities of CKD. These agents, with their promise of easier management and a reduced need for monitoring, have begun to reshape the contours of care, particularly for patients not yet on dialysis. However, this is not without its caveats. The application of DOACs in the context of advanced CKD remains a largely uncharted territory, necessitating a cautious exploration to unearth their true potential and limitations. Moreover, the advent of innovative strategies such as left atrial appendage occlusion (LAAO) underscores the dynamic nature of anticoagulation therapy, potentially offering a tailored solution for those at the intersection of CKD and elevated stroke risk. Yet the journey toward integrating such advancements into standard practice is laden with unanswered questions, demanding rigorous investigation to illuminate their efficacy and safety across the spectrum of kidney disease. In summary, the management of anticoagulation in CKD is a delicate dance, requiring a harmonious blend of precision, caution, and innovation. As we venture further into this complex domain, we must build upon our current understanding, embracing both emerging therapies and the need for ongoing research. Only then can we hope to offer our patients a path that navigates the narrow strait between bleeding and clotting, toward safer and more effective care.

Kinetic-pharmacodynamic model of warfarin for prothrombin time-international normalized ratio in Japanese patients

AIMS

Genotype-guided dosing algorithms can explain about half of the interindividual variability in prothrombin time-international normalized ratio (PT-INR) under warfarin treatment. This study aimed to refine a published kinetic-pharmacodynamic model and guide warfarin dosage for an optimal PT-INR based on renal function.

METHODS

Using a retrospective cohort of adult patients (>20 years) who were administered warfarin and underwent PT-INR measurements, we refined the kinetic-pharmacodynamic model with age and the genotypes of cytochrome P450 2C9 and vitamin K epoxide reductase complex subunit 1 using the PRIOR subroutine in the nonlinear-mixed-effect modelling programme. We searched the significant covariates for parameters, such as the dose rate for 50% inhibition of coagulation (EDR50 ), using a stepwise forward and backward method. Monte Carlo simulation determined a required daily dose of warfarin with a target range of PT-INR (2.0-3.0 or 1.6-2.6) based on the significant covariates.

RESULTS

A total of 350 patients with 2762 PT-INR measurements were enrolled (estimated glomerular filtration rate [eGFR]: 47.5 [range: 2.6-199.0] mL/min/1.73 m2 ). The final kinetic-pharmacodynamic model showed that the EDR50 changed power functionally with body surface area, serum albumin level and eGFR. Monte Carlo simulation revealed that a lower daily dose of warfarin was required to attain the target PT-INR range as eGFR decreased.

CONCLUSIONS

Model-informed precision dosing of warfarin is a valuable approach for estimating its dosage in patients with renal impairment.

Acute kidney injury interacts with VKORC1 genotype on initiative warfarin dose among heart surgery recipients: a real-world research

Patients who receive heart valve surgery need anticoagulation prophylaxis to reduce the risk of thrombosis. Warfarin often is a choice but its dosage varies due to gene and clinical factors. We aim to study, among them, if there is an interaction between acute kidney injury and two gene polymorphisms from this study. We extracted data of heart valve surgery recipients from the electronic health record (EHR) system of a medical center. The primary outcome is about the average daily dose of warfarin, measured as an additive interaction effect (INTadd) between acute kidney injury (AKI) and warfarin-related gene polymorphisms. The confounders, including age, sex, body surface area (BSA), comorbidities (i.e., atrial fibrillation [AF], hypertension [HTN], congestive heart failure [CHF]), serum albumin level, warfarin-relevant gene polymorphism (i.e., CYP2C9, VKORC1), prosthetic valve type (i.e., metal, bio), and warfarin history were controlled via a multivariate-linear regression model. The study included 200 patients, among whom 108 (54.00%) are female. Further, the mean age is 54.45 years, 31 (15.50%) have CHF, and 40 (20.00%) patients were prescribed concomitant amiodarone, which potentially overlays with the warfarin prophylaxis period. During the follow-up, AKI occurred in 30 (15.00%) patients. VKORC1 mutation (1639G>A) occurred in 25 (12.50%) patients and CYPC29 *2 or *3 mutations presented in 20 patients (10.00%). We found a significant additive interaction effect between AKI and VKORC1 (- 1.17, 95% CI - 1.82 to - 0.53, p = 0.0004). This result suggests it is probable that there is an interaction between acute kidney injury and the VKORC1 polymorphism for the warfarin dose during the initial period of anticoagulation prophylaxis.

Anticoagulation in Patients with Chronic Kidney Disease

BACKGROUND

Both atrial fibrillation and venous thromboembolism (VTE) are highly prevalent among patients with chronic kidney disease (CKD). Until recently, warfarin was the most commonly prescribed oral anticoagulant. Direct oral anticoagulants (DOACs) have important advantages and have been shown to be noninferior to warfarin with respect to stroke prevention or recurrent VTE in the general population, with lower bleeding rates. This review article will provide available evidence on the use of DOACs in patients with CKD.

SUMMARY

In post hoc analyses of major randomized studies with DOACs for stroke prevention in atrial fibrillation, in the subgroup of participants with moderate CKD, defined as a creatinine clearance (CrCl) of 30-50 mL/min, dabigatran 150 mg and apixaban were associated with lower rates of stroke and systemic embolism, whereas apixaban and edoxaban were associated with lower bleeding and mortality rates, compared with warfarin. In retrospective observational studies in patients with advanced CKD (defined as a CrCl <30 mL/min) and atrial fibrillation, DOACs had similar efficacy with warfarin with numerically lower bleeding rates. All agents warrant dose adjustment in moderate-to-severe CKD. In patients on maintenance dialysis, the VALKYRIE trial, which was designed initially to study the effect of vitamin K on vascular calcification progression, established superiority for rivaroxaban compared with a vitamin K antagonist (VKA) in the extension phase. Two other clinical trials using apixaban (AXADIA and RENAL-AF) in this population were inconclusive due to recruitment challenges and low event rates. In post hoc analyses of randomized studies with DOACs in patients with VTE, in the subgroup of participants with moderate CKD at baseline, edoxaban was associated with lower rates of recurrent VTE, whereas rivaroxaban and dabigatran were associated with lower and higher bleeding rates, respectively, as compared to warfarin.

KEY MESSAGES

DOACs have revolutionized the management of atrial fibrillation and VTE, and they should be preferred over warfarin in patients with moderate-to-severe CKD with appropriate dose adjustment. Therapeutic drug monitoring with a valid technique may be considered to guide clinical management in individualized cases. Current evidence questions the need for oral anticoagulation in patients on maintenance dialysis with atrial fibrillation as both DOACs and VKAs are associated with high rates of major bleeding.

Protein induced by vitamin K absence or antagonist II: Experience to date and future directions

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer with high mortality. The realization of precision medicine in HCC relies upon efficient biomarkers. Protein induced by vitamin K absence or antagonist II (PIVKA-II) is an immature prothrombin with insufficient coagulation activity, overexpressing in HCC cells. Previous evidence confirmed the role of PIVKA-II in screening and diagnosing HCC. However, the increased PIVKA-II was observed not only in HCC, but also in non-HCC individuals such as vitamin K deficiency. The joint detection of PIVKA-II and other biomarkers could significantly improve diagnostic accuracy in HCC. Furthermore, PIVKA-II serves as a valuable prognostic predictor, transplantation eligibility, resectability, tumor recurrence, therapeutic efficacy, and malignant tumor behaviors. Additionally, PIVKA-II represents a potential target for agent development to establish new therapeutic strategies. Besides HCC, PIVKA-II also serves as a biomarker of vitamin K status. In this review, we assess the role of PIVKA-II in diagnosis, prediction, and treatment. Over the past decades, substantial progress has been achieved in the application of PIVKA-II. Exploration and innovation are required for further advances in the field of PIVKA-II investigation.

Oral Anticoagulation in Patients With Advanced Chronic Kidney Disease and Atrial Fibrillation: Beyond Anticoagulation

The optimal approach to prevent stroke and systemic embolism in patients with advanced chronic kidney disease (CKD) and atrial fibrillation remains unresolved. We conducted a narrative review to explore areas of uncertainty and opportunities for future research. First, the relationship between atrial fibrillation and stroke is more complex in patients with advanced CKD than in the general population. The currently employed risk stratification tools do not adequately discriminate between patients deriving a net benefit and those suffering a net harm from oral anticoagulation. Anticoagulation initiation should probably be more restrictive than is currently advocated by official guidelines. Recent evidence reveals that the superior benefit-risk profile of non-vitamin K antagonist oral anticoagulants (NOACs) vs vitamin K antagonists (VKAs) observed in the general population and in moderate CKD can be extended to advanced CKD. The NOACs yield better protection against stroke, cause less major bleeding, are associated with less acute kidney injury and a slower decline of CKD, and are associated with a lower incidence of cardiovascular events than VKAs. The VKAs may be harmful in CKD patients, in particular in patients with a high bleeding risk and labile international normalized ratio. The better safety and efficacy of NOACs as opposed to VKAs may be particularly evident in advanced CKD as a result of better on-target anticoagulation with NOACs, harmful off-target vascular effects of VKAs, and beneficial off-target vascular effects of NOACs. The intrinsic vasculoprotective effects of NOACs are supported by animal experimental evidence as well as by findings of large clinical trials and may result in use of NOACs beyond their anticoagulant properties.

Nonvalvular atrial fibrillation in patients undergoing chronic hemodialysis. Should dialysis patients with atrial fibrillation receive oral anticoagulation?

Chronic kidney disease (CKD) is an independent risk factor for presenting atrial fibrillation (AF), which conditions an increased risk already present in CKD of suffering a thromboembolic event. And this risk is even higher in the hemodialysis (HD) population. On the other hand, in CKD patients and even more so in HD patients, the probability of suffering serious bleeding is also higher. Therefore, there is no consensus on whether or not to anticoagulate this population. Taking as a model what is advised for the general population, the most common attitude among nephrologists has been to opt for anticoagulation, even though there is no randomized studies to support it. Classically, anticoagulation has been done with vitamin K antagonists, at high cost for our patients: severe bleeding events, vascular calcification, and progression of nephropathy, among other complications. With the emergence of direct-acting anticoagulants, a hopeful outlook was opened in the field of anticoagulation, as they were postulated as more effective and safer drugs than antivitamin K. However, in clinical practice, this has not been the case. In this paper we review various aspects of AF and its anticoagulant treatment in the HD population.

Oral anticoagulants, time in therapeutic range and renal function over time in real-life patients with atrial fibrillation and chronic kidney disease

Aims

To describe the use of warfarin and direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) and chronic kidney disease (CKD), to evaluate changes in renal function over time and predictors of rapid decline, and to describe time in therapeutic range (TTR) and predictors of poor TTR among patients on warfarin.

Methods and results

Using data from AuriculA, the Swedish oral anticoagulation registry, patients with AF on warfarin or DOAC were identified between 2013 and 2018 (N=6567). Estimated glomerular filtration rate (eGFR) was calculated and categorised into normal (≥90 mL/min/1.73 m²), mild CKD (60–89 mL/min/1.73 m²), moderate CKD (30–59 mL/min/1.73 m²), severe CKD (15–29 mL/min/1.73 m²) and end-stage CKD (<15 mL/min/1.73 m²)/dialysis. TTR was estimated using international normalised ratio (INR) measurements. Predictors of eGFR decline over time and of poor TTR were estimated using regression analysis. Between 2013 and 2018, use of DOAC increased from 9.2% to 89.3%, with a corresponding decline in warfarin. A similar trend was observed in patients with mild to moderate CKD, while DOAC over warfarin increased slower among patients with severe to end-stage CKD/dialysis. In patients treated with warfarin, the median TTR was 77.1%. Worse TTR was observed among patients with severe CKD (70.0%) and end-stage CKD/dialysis (67.5%). A gradual annual decline in eGFR was observed (−1.1 mL/min/1.73 m²), with a more rapid decline among patients with older age, female sex, diabetes mellitus and/or heart failure.

Conclusion

In patients with AF, use of DOAC has steadily increased across different CKD stages, but not in patients with severe to end-stage CKD/dialysis despite these patients having poor INR control. Patients with AF have a gradual decline in renal function, with a more rapid decline among a subgroup of patients.

Genome-wide polygenic score to predict chronic kidney disease across ancestries

Chronic kidney disease (CKD) is a common complex condition associated with high morbidity and mortality. Polygenic prediction could enhance CKD screening and prevention; however, this approach has not been optimized for ancestrally diverse populations. By combining APOL1 risk genotypes with genome-wide association studies (GWAS) of kidney function, we designed, optimized and validated a genome-wide polygenic score (GPS) for CKD. The new GPS was tested in 15 independent cohorts, including 3 cohorts of European ancestry (n = 97,050), 6 cohorts of African ancestry (n = 14,544), 4 cohorts of Asian ancestry (n = 8,625) and 2 admixed Latinx cohorts (n = 3,625). We demonstrated score transferability with reproducible performance across all tested cohorts. The top 2% of the GPS was associated with nearly threefold increased risk of CKD across ancestries. In African ancestry cohorts, the APOL1 risk genotype and polygenic component of the GPS had additive effects on the risk of CKD.

Safety of Non-Vitamin K Antagonist Oral Anticoagulant Treatment in Patients with Chronic Kidney Disease and Kidney Transplant Recipients

The use of novel oral anticoagulants in patients with impaired renal function or undergoing immunosuppressive therapy is limited due to the risk of drug-to-drug interactions and anticoagulation-related adverse events. This article aims to assess the current data on the safety of direct-acting oral anticoagulant-based therapy in the population of kidney transplant recipients and patients with impaired renal function. The most important factors affecting the safety of treatment are the incidence of bleeding events, thromboembolic events, deaths and drug-to-drug interactions. The available data were compared to the findings on warfarin-based anticoagulation. Findings on the use of novel oral anticoagulants in kidney transplant recipients are limited yet promising in terms of safety and efficacy of use. However, current recommendations state that the co-administration of non-vitamin K antagonist oral anticoagulants with several immunosuppressive agents is contraindicated.

Evaluation of Anticoagulation Control among Patients Taking Warfarin in University of Gondar Hospital, Northwest Ethiopia

INTRODUCTION

Warfarin is a widely used oral anticoagulant in clinical practice. It has variable intraindividual and interindividual dose response and a narrow therapeutic index. Therefore, it requires frequent and regular international normalized ratio (INR) determination to maintain the INR within the therapeutic range. The study evaluated parameters of anticoagulation control among patients on warfarin.

METHODS

A cross-sectional study was conducted at University of Gondar hospital. A consecutive sampling method was used to recruit study subjects. The anticoagulation control was evaluated by determining the proportion of desired INRs and the proportion of time spent in the therapeutic range (TTR). Logistic regression analysis was used to identify associated factors with adequate TTR. A P value <0.05 was used to declare significant association.

RESULT

A total of 338 study subjects were included in the study. The mean age of patients was 48.8 (SD = 16.4) years. Atrial fibrillation was the commonest indication for warfarin therapy. One-third (33%) of study subjects achieved the desired INRs of 2.0-3.0, while about one-tenth (13%) of patients attained good INR control (TTR ≥ 65%). Multivariate logistic regression analysis revealed no significant association of sociodemographic and clinical characteristics with good TTR outcome.

CONCLUSION

The level of anticoagulation control with warfarin among study subjects was very low. The authors recommend to implement a validated warfarin-dose titration protocol and to establish anticoagulation clinics to mitigate the low anticoagulation level.

Consequences of oral antithrombotic use in patients with chronic kidney disease

We assessed the risks of bleeding, acute kidney injury (AKI), and kidney failure associated with the prescription of antithrombotic agents (oral anticoagulants and/or antiplatelet agents) in patients with moderate-to-advanced chronic kidney disease (CKD). CKD-REIN is a prospective cohort of 3022 nephrology outpatients with CKD stages 2-5 at baseline. We used cause-specific Cox proportional hazard models to estimate hazard ratios (HRs) for bleeding (identified through hospitalizations), AKI, and kidney failure. Prescriptions of oral antithrombotics were treated as time-dependent variables. At baseline, 339 (11%) patients (65% men; 69 [60-76] years) were prescribed oral anticoagulants only, 1095 (36%) antiplatelets only, and 101 (3%) both type of oral antithrombotics. Over a median (interquartile range [IQR]) follow-up period of 3.0 (IQR, 2.8-3.1) years, 152 patients experienced a bleeding event, 414 patients experienced an episode of AKI, and 270 experienced kidney failure. The adjusted HRs (95% confidence interval [95% CI]) for bleeding associated with prescriptions of antiplatelets only, oral anticoagulants only, and antiplatelet + oral anticoagulant were, respectively, 0.74 (95% CI, 0.46-1.19), 2.38 (95% CI, 1.45-3.89), and 3.96 (95% CI, 2.20-7.12). An increased risk of AKI risk was associated with the prescription of oral anticoagulants (adjusted HR, 1.90, 95% CI, 1.47-2.45) but not the prescription of antiplatelets (HR, 1.24, 95% CI, 0.98-1.56). Kidney failure was not associated with the prescription of oral antithrombotics of any type. This study confirms the high risk of AKI associated with oral anticoagulants prescription in patients with CKD and also highlights the potential aggravating effect of combining vitamin K antagonist (VKA) and antiplatelets on the risk of bleeding.

Non-valvular Atrial Fibrillation in CKD: Role of Vitamin K Antagonists and Direct Oral Anticoagulants. A Narrative Review

Atrial fibrillation (AF) is the most common arrhythmia in chronic kidney disease (CKD), with a close bidirectional relationship between the two entities. The presence of CKD in AF increases the risk of thromboembolic events, mortality and bleeding. Vitamin K antagonists (VKA) have been the mainstay of treatment for the prevention of thromboembolic events in AF until recently, with confirmed benefits in AF patients with stage 3 CKD. However, the risk-benefit profile of VKA in patients with AF and stages 4-5 CKD is controversial due to the lack of evidence from randomized controlled trials. Treatment with VKA in CKD patients has been associated with conditions such as poorer anticoagulation quality, increased risk of bleeding, faster progression of vascular/valvular calcification and higher risk of calciphylaxis. Direct oral anticoagulants (DOACs) have shown equal or greater efficacy in stroke/systemic embolism prevention, and a better safety profile than VKA in post-hoc analysis of the pivotal randomized controlled trials in patients with non-valvular AF and stage 3 CKD, yet evidence of its risk-benefit profile in more advanced stages of CKD is scarce. Observational studies associate DOACs with a good safety/effectiveness profile compared to VKA in non-dialysis CKD patients. Further, DOACs have been associated with a lower risk of acute kidney injury and CKD development/progression than VKA. This narrative review summarizes the evidence of the efficacy and safety of warfarin and DOACs in patients with AF at different CKD stages, as well as their effects on renal function, vascular/valvular calcification and bone health.

Thromboembolic and Hemorrhagic Outcomes in the Direct Oral Anticoagulant Trials Across the Spectrum of Kidney Function

Chronic kidney disease is a common comorbidity among patients taking direct-acting oral anticoagulants (DOACs). Herein, we evaluate the influence of kidney function on stroke or systemic embolism (SEE), hemorrhage, and composite end points (stroke/SEE/hemorrhage/death and stroke/SEE/death) among patients on DOACs and warfarin. Baseline kidney function was categorized as glomerular filtration rate (GFR) ≥ 60 (reference), 45-59, and < 45mL/min/1.73 m2 for participants in the Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) (n = 18,049), Apixaban for Reduction in Stroke and Other Thromboembolic Events (ARISTOTLE) (n = 18,187), and The Effective Anticoagulation with Factor Xa Next Generation in AF (ENGAGE AF) (n = 20,798) trials. Incidence of events was compared across GFR categories. Hazard ratios for events were estimated using Cox regression using intention-to-treat analysis adjusting for known predictors. A large proportion of participants had GFR < 60 (25-29% had 45 ≤ GFR < 60 and 9.5-12.6% with GFR < 45). Compared with patients with GFR ≥ 60, warfarin users across the trials with GFR ≥ 45-59 and GFR < 45 had a higher incidence of hemorrhage (P values < 0.0001) and warfarin users in the ARISTOTLE and ENGAGE trials had higher incidence of stroke/SEE (P values ≤ 0.05). Compared with patients with GFR ≥ 60, dabigatran users with GFR ≥ 45-59 and GFR < 45 had a higher incidence of stroke/SEE (P ≤ 0.02), hemorrhage (P < 0.001), and both composite end points (P < 0.0001). Compared with patients with GFR ≥ 60, apixaban and edoxaban users with GFR ≥ 45-59 and GFR < 45 had a higher incidence of hemorrhage (P values ≤ 0.05) and composite end points (P values ≤ 0.05). After adjustment, compared with patients with GFR ≥ 60, warfarin users with GFR < 60 in the ARISTOTLE and RE-LY trials had a higher risk of hemorrhage (P < 0.05), as did dabigatran (P < 0.001) and edoxaban (P ≤ 0.005) users, while apixaban users did not exhibit an increased risk (P = 0.08 GFR ≥ 45-59; P = 0.71 GFR < 45). Kidney function significantly influences the safety and efficacy of oral anticoagulants.

Risk of over-anticoagulation during acute kidney injury in patients treated with vitamin K antagonists

Background

Vitamin K antagonists (VKAs) are still in use for oral anticoagulation, but not all indications allow their replacement by direct oral anticoagulants. Although formal dose reduction is not required in patients with impaired kidney function, case reports indicate that acute kidney injury (AKI) might be associated with derailment of VKA therapy.

Methods

The study retrospectively collected patients from a tertiary nephrology care centre who experienced AKI while being treated with VKA. In these individuals, the international normalized ratio (INR) as a measure of anticoagulant effect during renal failure was compared with a reference time point with stable kidney function.

Results

A total of 100 patients with AKI and ongoing VKA therapy met the inclusion criteria. The majority (76%) of patients had AKI with CKD. Volume depletion (n = 43), septic renal failure (n = 22), decompensated heart failure (n = 18) and toxic renal damage (n = 11) were the most important causes of AKI. The average INR values at the time of AKI were higher than at the reference time point [median 3.17 (range 1.10–13.0) versus 2.24 (1.07–5.17); P < 0.0001]. Fifty-four patients had INR values above the recommended therapeutic range for their indication at the time point of AKI. Bleeding complications occurred in 24 patients during AKI and the VKA dose had to be reduced in 55. Women, patients with low body mass index and patients with diabetes were predisposed to overanticoagulation during AKI.

Conclusions

The effect of AKI on anticoagulation by VKA has not been systematically described. This risk should be considered in patients at high risk for AKI.

Pros and cons of antithrombotic therapy in end-stage kidney disease: a 2019 update

Dialysis patients manifest both an increased thrombotic risk and a haemorrhagic tendency. A great number of patients with chronic kidney disease requiring dialysis have cardiovascular comorbidities (coronary artery disease, atrial fibrillation or venous thromboembolism) and different indications for treatment with antithrombotics (primary or secondary prevention). Unfortunately, few randomized controlled trials deal with antiplatelet and/or anticoagulant therapy in dialysis. Therefore cardiology and nephrology guidelines offer ambiguous recommendations and often exclude or ignore these patients. In our opinion, there is a need for an expert consensus that provides physicians with useful information to make correct decisions in different situations requiring antithrombotics. Herein the European Dialysis Working Group presents up-to-date evidence about the topic and encourages practitioners to choose among alternatives in order to limit bleeding and minimize atherothrombotic and cardioembolic risks. In the absence of clear evidence, these clinical settings and consequent therapeutic strategies will be discussed by highlighting data from observational studies for and against the use of antiplatelet and anticoagulant drugs alone or in combination. Until new studies shed light on unclear clinical situations, one should keep in mind that the objective of treatment is to minimize thrombotic risk while reducing bleeding events.

Percutaneous left atrial appendage closure, a safe alternative to anticoagulation for patients with nonvalvular atrial fibrillation and end-stage renal disease on hemodialysis: A single center experience

The evidence about the effectiveness and safety of oral anticoagulation in patients on hemodialysis is conflicting and scarce. Percutaneous left atrial appendage occlusion (LAAO) has demonstrated to be a valid alternative therapeutic option for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF). The aim of this study is to present the outcomes of percutaneous LAAO in patients with end-stage renal disease (ESRD) on hemodialysis and NVAF in our center. We conducted a retrospective review of clinical records, demographics, LAAO procedure, complications, and outcomes of patients with NVAF and ESRD on hemodialysis who underwent a percutaneous LAAO in our center between January 2017 and January 2019. In the period of the study, eight patients with ESRD on hemodialysis underwent a percutaneous LAAO in our center. The overall mean age was 67.5 years (range 56-81; SD ± 7.2). All patients had permanent NVAF. The total mean dialysis duration was 8.49 years (range 0.83-14.8; SD ± 6.2). The mean CHA2DS2-VASc and HAS-BLED scores were high (4.75 [SD ± 1.16] and 4.62 [SD ± 0.91], respectively). All patients had history of a major hemorrhagic event (BARC Score ≥3). Most patients (n = 6) showed left ventricular hypertrophy, and the average LVEF was 54% (SD ± 6.5). All devices were implanted successfully. Postprocedural antithrombotic regimen prescribed was based on antiplatelet therapy. No deaths, cardioembolic events, or major bleeding (according to the BARC scale) were reported during a mean follow-up of 14.24 months (SD ± 9.44). Percutaneous LAAO could be of particular interest in patients with NVAF and CKD in hemodialysis. Further studies will be necessary to confirm this hypothesis.

Anticoagulation in chronic kidney disease: from guidelines to clinical practice

BACKGROUND

Chronic kidney disease (CKD) is a major global public health problem, being closely connected to cardiovascular disease. CKD involves an elevated thromboembolic risk and requires anticoagulation, but the high rates of hemorrhage render it quite challenging.

HYPOTHESIS

There are no consensus recommendations regarding anticoagulation in CKD. Due to the currently limited data, clinicians need practical clues for monitoring and optimizing the treatment.

METHODS

Based on the available data, this review outlines the benefit-risk ratio of all types of anticoagulants in each stage of CKD and provides practical recommendations for accurate dosage adjustment, reversal of antithrombotic effect, and monitoring of renal function on a regular basis.

RESULTS

Evidence from randomized controlled trials supports the efficient and safe use of warfarin and direct oral anticoagulants (DOACs) in mild and moderate CKD. On the contrary, the data are poor and controversial for advanced stages. DOACs are preferred in CKD stages 1 to 3. In patients with stage 4 CKD, the choice of warfarin vs DOACs will take into consideration the pharmacokinetics of the drugs and patient characteristics. Warfarin remains the first-line treatment in end-stage renal disease, although in this case the decision to use or not to use anticoagulation is strictly individualized. Anticoagulation with heparins is safe in nondialysis-dependent CKD, but remains a challenge in the hemodialysis patients.

CONCLUSIONS

Although there is a need for cardiorenal consensus regarding anticoagulation in CKD, adequate selection of the anticoagulant type and careful monitoring are some extremely useful indications for overcoming management challenges.

[The Nephrological Aspects of the Use of Rivaroxaban and Other Direct Peroral Anticoagulants in Non-Valvular Atrial Fibrillation]

Chronic kidney disease (CKD) is a powerful cardiovascular risk factor, its presence is accompanied by an increased risk of hospitalization for exacerbation of chronic heart failure (CHF), adverse outcomes in myocardial infarction, and cardiovascular mortality. Among the adverse events, an increased risk of atrial fibrillation (AF) should be noted. This article contains discussion of current approaches to the treatment of AF in patients with different stages of CKD, data on benefits of certain direct oral anticoagulants, as well as comparative characteristics of therapy with direct oral anticoagulants and warfarin. Pharmacokinetics and pharmacodynamics of direct oral anticoagulants, which determine the features of therapy in CKD, are also considered.

Clinical Pharmacology of Oral Anticoagulants in Patients with Kidney Disease

Oral anticoagulants are commonly used drugs in patients with CKD and patients with ESKD to treat atrial fibrillation to reduce stroke and systemic embolism. Some of these drugs are used to treat or prevent deep venous thrombosis and pulmonary embolism in patients with CKD who undergo knee and hip replacement surgeries. Warfarin is the only anticoagulant that is approved for use by the Food and Drug Administration in individuals with mechanical heart valves. Each oral anticoagulant affects the coagulation profile in the laboratory uniquely. Warfarin and apixaban are the only anticoagulants that are Food and Drug Administration approved for use in patients with CKD and patients with ESKD. However, other oral anticoagulants are commonly used off label in this patient population. Given the acquired risk of bleeding from uremia, these drugs are known to cause increased bleeding events, hospitalization, and overall morbidity. Each anticoagulant has unique pharmacologic properties of which nephrologists need to be aware to optimally manage patients. In addition, nephrologists are increasingly asked to aid in the management of adverse bleeding events related to oral anticoagulant use in patients with CKD and patients with ESKD. This article summarizes the clinical pharmacology of these drugs and identifies knowledge gaps in the literature related to their use.

Management and 1-Year Outcomes of Patients With Newly Diagnosed Atrial Fibrillation and Chronic Kidney Disease: Results From the Prospective GARFIELD - AF Registry

Background Using data from the GARFIELD - AF (Global Anticoagulant Registry in the FIELD -Atrial Fibrillation), we evaluated the impact of chronic kidney disease ( CKD ) stage on clinical outcomes in patients with newly diagnosed atrial fibrillation ( AF ). Methods and Results GARFIELD - AF is a prospective registry of patients from 35 countries, including patients from Asia (China, India, Japan, Singapore, South Korea, and Thailand). Consecutive patients enrolled (2013-2016) were classified with no, mild, or moderate-to-severe CKD , based on the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative guidelines. Data on CKD status and outcomes were available for 33 024 of 34 854 patients (including 9491 patients from Asia); 10.9% (n=3613) had moderate-to-severe CKD , 16.9% (n=5595) mild CKD , and 72.1% (n=23 816) no CKD . The use of oral anticoagulants was influenced by stroke risk (ie, post hoc assessment of CHA 2 DS 2- VAS c score), but not by CKD stage. The quality of anticoagulant control with vitamin K antagonists did not differ with CKD stage. After adjusting for baseline characteristics and antithrombotic use, both mild and moderate-to-severe CKD were independent risk factors for all-cause mortality. Moderate-to-severe CKD was independently associated with a higher risk of stroke/systemic embolism, major bleeding, new-onset acute coronary syndrome, and new or worsening heart failure. The impact of moderate-to-severe CKD on mortality was significantly greater in patients from Asia than the rest of the world ( P=0.001). Conclusions In GARFIELD - AF , moderate-to-severe CKD was independently associated with stroke/systemic embolism, major bleeding, and mortality. The effect of moderate-to-severe CKD on mortality was even greater in patients from Asia than the rest of the world. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 01090362.

Atrial fibrillation in patients with first-ever stroke: Incidence trends and antithrombotic therapy before the event

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia among adults. Despite the proven advantages in primary and secondary stroke prevention in patients with AF, oral anticoagulation (OAC) therapy is still underused in many countries. In this study, we investigated the incidence of AF-related ischemic stroke over the past decade in South Korea and trends of preventive antithrombotic therapy use before stroke in a nationwide cohort.

Methods and findings

The data source for this study was a nationwide sample cohort comprising 1,025,340 individuals that was established by the nationwide health insurance system in 2002. A total of 10,215 patients with acute ischemic stroke (AIS) were selected from the cohort between 2004 and 2013. AF was identified in 1,662 patients, and 979 patients had preexisting AF before AIS. The annual proportion of patients with AIS with AF gradually increased from 13.4% to 22.6% over the study period (p for trends <0.001). Only 14.0% of patients with high risk AF were receiving OAC before the stroke, and this proportion remained relatively constant during the study period. However, the proportion of patients treated with antiplatelet agents had increased from 18.8% in 2004 to 45.3% in 2013, while that of patients receiving no antithrombotic agent decreased from 64.6% in 2004 to 43.9% in 2013. As a limitation, no information was available about non-vitamin K antagonist oral anticoagulants, because they were widely used since late 2014 in Korea.

Conclusions

The number of patients with AIS and AF has steadily increased over the last 10 years in Korea. However, a small portion of patients with AF were receiving OAC therapy before the stroke and about half of the patients did not receive any antithrombotic medication. Our study demonstrates that there is huge gap between clinical practice and treatment guidelines for patients with AF in Korea.

Mechanisms and mitigating factors for venous thromboembolism in chronic kidney disease: the REGARDS study

Essentials Chronic kidney disease (CKD) is associated with procoagulant and inflammatory biomarkers. We studied the association of CKD and venous thromboembolism (VTE) in a case-cohort study. Factor VIII, D-dimer and C-reactive protein appeared to explain the association of CKD and VTE. Statin use was protective against VTE in those with and without CKD.

SUMMARY

Background Chronic kidney disease (CKD) is associated with venous thromboembolism (VTE) risk via unknown mechanisms. Whether factors associated with reduced VTE risk in the general population might also be associated with reduced VTE risk in CKD patients is unknown. Objectives To determine whether thrombosis biomarkers attenuate VTE risk, and whether factors associated with reduced VTE risk are similarly effective in CKD patients. Methods Baseline biomarkers were measured in a cohort (294 VTE cases; 939 non-cases) from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a nationwide prospective cohort study of 30 239 persons aged ≥45 years with 4.3 years of follow-up. The hazard ratio (HR) of VTE per 10 mL min-1 1.73 m-2 decrease in estimated glomerular filtration rate (eGFR), and the percentage attenuation of this HR by each biomarker, were calculated. Associations of protective factors (physical activity, lower body mass index [BMI], and aspirin, warfarin and statin use) with VTE were estimated in those with and without CKD. Results The HR for VTE with lower eGFR was 1.13 (95% confidence interval [CI] 1.02-1.25), and VTE risk was attenuated by 23% (95% CI 5-100) by D-dimer, by 100% (95% CI 50-100) by factor VIII, and by 15% (95% CI 2-84) by C-reactive protein. Normal BMI was associated with lower VTE risk in those without CKD (HR 0.47, 95% CI 0.32-0.70), but not in those with CKD (HR 1.07, 95% CI 0.51-2.22). Statin use, physical activity and warfarin use were associated with lower VTE risk in both groups. Conclusions Procoagulant and inflammatory biomarkers mediated the association of eGFR with VTE. Higher physical activity, statin use and warfarin use mitigated VTE risk in those with CKD and those without CKD, but normal BMI did not mitigate VTE risk in CKD patients.

Long-term prognostic impact of anticoagulation on patients with atrial fibrillation undergoing hemodialysis

INTRODUCTION AND OBJECTIVES

Evidence for the efficacy and safety of oral anticoagulation with dicumarines in patients with atrial fibrillation (AF) on hemodialysis is controversial. The aim of our study is to evaluate the long-term prognostic implications of anticoagulation with dicumarines in a cohort of patients with non-valvular AF on a hemodialysis program due to end-stage renal disease.

METHODS

Retrospective, observational study with consecutive inclusion of 74 patients with AF on hemodialysis. The inclusion period was from January 2005 to October 2016. The primary variables were all-cause mortality, non-scheduled readmissions and bleeding during follow-up.

RESULTS

Mean age was 75±10 years; 66.2% were men and 43 patients (58.1%) received acenocoumarol. During a median follow-up of 2.40 years (IQR=0.88-4.15), acenocoumarol showed no survival benefit [HR=0.76, 95% CI (0.35-1.66), p=0.494]. However, anticoagulated patients were at increased risk of recurrent cardiovascular hospitalizations [IRR=3.94, 95% CI (1.06-14.69), p=0.041]. There was a trend towards an increase in repeated hospitalizations of ischemic cause in anticoagulated patients [IRR=5.80, 95% CI (0.86-39.0), p=0.071]. There was a statistical trend towards a higher risk of recurrent total bleeding in patients treated with acenocoumarol [IRR=4.43, 95% CI (0.94-20.81), p=0.059].

CONCLUSIONS

In this study, oral anticoagulation with acenocoumarol in patients with AF on hemodialysis did not increase survival. However, it was associated with an increased risk of hospitalizations of cardiovascular causes and a tendency to an increased risk of total bleeding.

Bleeding in advanced CKD patients on antithrombotic medication - A critical appraisal

Patients with advanced chronic kidney disease (CKD) are at an increased risk of bleeding, especially in the context of the complex therapeutic schemes of coronary artery disease (CAD) (from stable angina to acute coronary syndromes), atrial fibrillation or venous thromboembolism. The bleeding issue increases morbidity and mortality, a serious problem in daily medical practice. However, these patients are largely excluded from major randomized clinical trials, which results in the lack of medical evidence-based foundation for specific recommendations regarding antithrombotic treatment in a high bleeding risk setting. Within this framework, the clinician does not benefit from a clear set of algorithms and measures in the exploration and balancing of bleeding and thrombosis risks. We discuss a diversity of scenarios, encompassing all categories of advanced CKD patients with CAD or/and atrial fibrillation, and with various combinations of drugs, such as antiplatelet therapy or/and oral anticoagulation. Our review highlights the most recent research as well as existing gaps in the recommendations of European Society of Cardiology Guidelines. We evaluate the existence or lack of assessment tools for the bleeding risk, strength, reliability and usefulness of the bleeding risk scores. Also, we identify all the measures recommended after risk evaluation, including specific plans, dose adjustments and particular therapeutic approaches. Finally, we provide with suggestions for improving the management of this patient population.

Cessation of oral anticoagulation is an important risk factor for stroke and mortality in atrial fibrillation patients

Oral anticoagulation (OAC) is highly effective preventing stroke and mortality in AF, but withdrawal is common in the elderly, when high bleeding risk and when are difficulties achieving an optimal time in therapeutic range (TTR). We analysed the rate of OAC cessation, predisposing factors to cessation and the relation to clinical outcomes in a large ‘real world’ cohort of AF patients over a long follow-up period. Consecutive non-valvular AF outpatients clinically stables for six months were recruited. Rates of cardiovascular events, major bleeding and mortality were recorded and related to OAC cessation. We included 1361 patients (48.7 % male; aged 76, IQR 71–81), followed-up for a median of 6.5 years. During follow-up, 244 patients suffered thrombotic events, 250 suffered from major bleeding and 551 patients died. 10 % of patients stopped OAC. After OAC withdrawal, there were 36 thromboembolic events (22 strokes), 10 major bleedings and 75 deaths. OAC cessation was independently associated with adverse cardiovascular events (HR 1.45; 95 % CI 1.01–2.08), stroke/TIA (HR 1.85; 1.17–2.94) and all-cause mortality (HR 1.30; 1.02–1.67). Independent predictors of OAC cessation were age ≥80 (HR 2.29; 1.60–3.29), previous coronary artery disease (HR 0.32; 0.15–0.71), major bleeding (HR 5.00; 3.49–7.15), heart failure (HR 2.38; 1.26–4.47), cancer (HR 5.24; 3.25–8.44) and renal impairment developed during follow-up (HR 2.70; 1.26–5.75). In conclusion, in non-valvular AF patients, cessation of OAC was independently associated with the risk of stroke, adverse cardiovascular events and mortality. Bleeding events and some variables associated with higher bleeding risk are responsible for OAC cessation.

Note: The review process for this manuscript was fully handled by Christian Weber, Editor in Chief.

Supplementary Material to this article is available online at www.thrombosis-online.com.

No Evidence for an Association Between Renal Function and Serious Bleeding Events in Patients Treated With Coumarins: A Population-Based Study

BACKGROUND

Although anticoagulation therapy is closely monitored in the Netherlands, coumarin-induced serious bleeding events are still observed. Current literature suggests that renal impairment may contribute to this.

OBJECTIVE

To explore the association between renal function and bleeding events during coumarin treatment.

METHODS

A nested case-control study was conducted using data from the PHARMO Database Network. Patients hospitalized for a bleeding event during coumarin treatment were selected as cases and matched on sex, birth year, and geographic region to up to 2 controls using coumarins without hospitalization for bleeding. All values of estimated glomerular filtration rates (eGFRs) were selected in the year before index date (case hospitalization date) and compared between cases and controls using logistic regression analyses.

RESULTS

In total, 2224 cases were matched to 4398 controls (61% male; mean ± SD age 75 ± 11 and 78 ± 11 years among cases and controls, respectively). Availability of eGFR values was higher among cases compared with controls (mean ± SD eGFR values 4.5 ± 7.1 vs 3.2 ± 5.5), reflected in the significantly shorter time since last eGFR value (at index date, mean ± SD = 2.7 ± 3.0 vs 3.8 ± 3.1 months; odds ratio [OR] = 0.91, 95%CI = 0.89-0.92). No statistically significant difference was found for the mean eGFR value in the year before index date (mean ± SD 65.7 ± 22.8 vs 64.6 ± 20.9 mL/min/1.73 m²; OR per 10 units [95%CI] = 0.99 [0.96-1.02]).

CONCLUSIONS

No association between renal function and serious bleeding events during coumarin treatment was observed.

Influence of Kidney Transplant Status on Warfarin Dose, Anticoagulation Control, and Risk of Hemorrhage

STUDY DESIGN

To assess whether warfarin dose requirement, anticoagulation control, and risk of hemorrhage differ in kidney transplant recipients (KTRs) compared with patients without kidney transplants (non-KTRs).

DESIGN

Analysis of data from the Warfarin Pharmacogenetics Cohort, a prospective cohort of first-time warfarin users followed at two anticoagulation clinics.

SETTING

Two outpatient anticoagulation clinics at two large, academic, tertiary care hospitals.

PATIENTS

Adults aged 20 years or older starting warfarin for anticoagulation with a therapeutic international normalized ratio (INR) goal of 2-3 who were KTRs (n=65) or non-KTRs (n=1630).

MEASUREMENTS AND MAIN RESULTS

Warfarin dose requirement, anticoagulation control, and risk of hemorrhage were assessed in each group. KTRs required an approximately 20% lower warfarin dose (4.7 vs 5.6 mg/day, p=0.0005) compared with non-KTRs. Genetic variants had similar effects on dose in both groups. Mean percentage of time in therapeutic range (PTTR) was similar among KTRs and non-KTRs. Although the proportion of patients achieving good anticoagulation control (PTTR ≥ 60%) was low in both groups, it was similar among KTRs and non-KTRs. KTRs had a higher risk of major hemorrhage (hazard ratio 2.1, p=0.0081), but this difference was not statistically significant after controlling for kidney function, clinical, and genetic factors.

CONCLUSION

KTRs initiating warfarin require lower doses and closer monitoring to optimize anticoagulation therapy. Additional studies are needed to confirm these findings.

Time in Therapeutic Range and Outcomes After Warfarin Initiation in Newly Diagnosed Atrial Fibrillation Patients With Renal Dysfunction

Background

It is unknown whether renal dysfunction conveys poor anticoagulation control in warfarin‐treated patients with atrial fibrillation and whether poor anticoagulation control associates with the risk of adverse outcomes in these patients.

Methods and Results

This was an observational study from the Stockholm CREatinine Measurements (SCREAM) cohort including all newly diagnosed atrial fibrillation patients initiating treatment with warfarin (n=7738) in Stockholm, Sweden, between 2006 and 2011. Estimated glomerular filtration rate (eGFR; mL/min per 1.73 m²) was calculated from serum creatinine. Time‐in‐therapeutic range (TTR) was assessed from international normalized ratio (INR) measurements up to warfarin cessation, adverse event, or end of follow‐up (2 years). Adverse events considered a composite of intracranial hemorrhage, ischemic stroke, myocardial infarction, or death. During median 254 days, TTR was 83%, based on median 21 INR measurements per patient. TTR was 70% among patients with eGFR <30, around 10% lower than in those with normal renal function. During observation, adverse events occurred in 4.0% of patients, and those with TTR ≤75% were at higher adverse event risk. This was independent of patient characteristics, comorbidities, number of INR tests, days exposed to warfarin, and, notably, independent of eGFR: adjusted odds ratio (OR) 1.84 (95% CI, 1.41–2.40) for TTR 75% to 60% and adjusted OR 2.09 (1.59–2.74) for TTR <60%. No interaction was observed between eGFR and TTR in association to adverse events (P=0.2).

Conclusion

Severe chronic kidney disease (eGFR <30) patients with atrial fibrillation have worse INR control while on warfarin. An optimal TTR (>75%) is associated with lower risk of adverse events, independently of underlying renal function.

Renal Function and the Risk of Stroke and Bleeding in Patients With Atrial Fibrillation

Background and Purpose—

We sought to determine the risk of stroke/thromboembolism and bleeding associated with reduced renal function in patients with atrial fibrillation and the risk of stroke and bleeding associated with warfarin treatment in specific estimated glomerular filtration rate (eGFR) groups.

Methods—

We conducted a register-based cohort study and included patients discharged with nonvalvular atrial fibrillation from 1997 to 2011 with available eGFR.

Results—

A total of 17 349 patients were identified with eGFR available at baseline. All levels of lower eGFR were associated with higher risk of stroke/thromboembolism and bleeding. Use of warfarin was associated with higher bleeding risk in all eGFR groups; hazard ratios 1.23 (95% confidence interval [CI], 0.97–1.56), 1.26 (95% CI, 1.14–1.40), 1.18 (95% CI, 1.07–1.31), 1.11 (95% CI, 0.87–1.42), 2.01 (95% CI, 1.14–3.54) in patients with eGFR ≥90, 60 to 89, 30 to 59, 15 to 29, and <15 mL/min per 1.73 m 2 , respectively. Use of warfarin was associated with lower risk of stroke/thromboembolism in patients with eGFR ≥15 mL/min per 1.73 m 2 ; hazard ratios 0.57 (95% CI, 0.43–0.76), 0.57 (95% CI, 0.51–0.64), 0.48 (95% CI, 0.44–0.54), 0.60 (95% CI, 0.45–0.80) in patients with eGFR ≥90, 60 to 89, 30 to 59, and 15 to 29 mL/min per 1.73 m 2 , respectively. Use of warfarin was not associated with lower risk of stroke/thromboembolism in patients with eGFR<15 mL/min per 1.73 m 2 ; hazard ratio 1.18 (95% CI, 0.58–2.40).

Conclusions—

In patients with atrial fibrillation, the risk of stroke and bleeding was associated with levels of renal function. Warfarin treatment was associated with higher risk of bleeding in all eGFR groups and lower risk of stroke in patients with eGFR≥15 mL/min per 1.73 m 2 .

Use of direct oral anticoagulants in patients with nonvalvular atrial fibrillation according to clinical profile

The majority of patients with atrial fibrillation should receive oral anticoagulation to reduce the risk of stroke. The limitations of vitamin K antagonists have led to an underuse of anticoagulants in clinical practice which has been associated with a higher risk of stroke, hospitalizations and healthcare costs. Direct oral anticoagulants (DOACs) overcome some of the limitations of vitamin K antagonists and may therefore increase the use of oral anticoagulants in clinical practice. Since no head-to-head trials have been performed, only indirect comparisons can be made among them. In this review, the results of the Phase III randomized controlled trials with DOACs were analyzed, trying to determine whether one or more DOACs could be especially recommended according to different clinical conditions.

Chronic Kidney Disease, Time in Therapeutic Range and Adverse Clinical Outcomes in Anticoagulated Patients with Non-valvular Atrial Fibrillation: Observations from the SPORTIF Trials

Background

Chronic kidney disease (CKD) is highly prevalent in atrial fibrillation (AF) patients and associated with an increased risk of adverse outcomes. Our objectives were to study clinical features associated with CKD in AF patients and the impact of CKD on anticoagulation control, as reflected by time in therapeutic range (TTR). We also determined the impact of CKD and TTR in predicting adverse outcomes.

Methods and Results

We analysed pooled datasets from SPORTIF III and V trials, including 3646 patients assigned to warfarin with data on renal function. CKD (creatinine clearance < 60 ml/min) was present in 952 (26%) patients. TTR was higher in patients with normal renal function compared to those with CKD (p < 0.001).

On logistic analysis, chronic AF and male sex were associated with TTR > 70%, whilst diabetes mellitus, aspirin use and CKD were inversely associated with TTR > 70%. On Cox regression analysis, CKD was an independent predictor for stroke (p = 0.006) and death (p < 0.001). TTR > 70% was independently associated with a lower risk of stroke (p = 0.024), death (p = 0.001) and major bleeding (p = 0.001).

Conclusions

CKD is highly prevalent amongst AF patients and a risk factor for stroke and death. Adjusting for CKD, good quality anticoagulation control (TTR > 70%) was an independent predictor for lower risks of stroke, death and major bleeding.

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Chronic kidney disease (CKD) in atrial fibrillation (AF) patients is associated with several clinical factors.

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There is a linear association between creatinine clearance and time in therapeutic range (TTR).

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CKD is a risk factor for stroke and death, while TTR > 70% is a predictor for stroke, major bleeding and death.

The concomitant presence of atrial fibrillation (AF) and chronic kidney disease (CKD) confers an increased risk of both ithromboembolism and bleeding. Oral anticoagulation with vitamin K antagonist (VKA) are an effective treatment in preventing thromboembolic events, but good anticoagulation control as reflected by a high time in therapeutic range (TTR) is crucial in reducing thromboembolic and bleeding adverse events. Our results showed a close relationship between CKD, TTR and adverse events. In the decision-making process of prescribing VKA, clinicians need to consider renal function as well as good anticoagulation control (e.g. TTR > 70%) to ensure best efficacy and safety.

Oral anticoagulants and risk of nephropathy

Anticoagulant-related nephropathy, a recently recognized entity, manifests as unexplained acute kidney injury in the setting of excessive anticoagulation with oral agents. Histologic findings in warfarin-related nephropathy include glomerular hemorrhage and renal tubular obstruction by red blood cells. Affected patients are at increased risk of mortality as well as irreversible kidney injury. Patients with chronic kidney disease are particularly vulnerable to this complication. Similar case reports of anticoagulant-related nephropathy have been linked to the more novel oral anticoagulant, dabigatran. Anticoagulant-related nephropathy has been successfully reproduced in rat models. These animal models shed light on the pathogenesis of the disease including the potential role of direct thrombin and protease-activated receptor-1 inhibition. Warfarin and dabigatran also cause an increase in systolic blood pressure in rats, a risk factor for developing nephropathy. This article reviews the current evidence for anticoagulant-related nephropathy and provides data for the suggested possible mechanisms underlying this adverse effect.

Concepts and Controversies in Evaluating Vitamin K Status in Population-Based Studies

A better understanding of vitamin K's role in health and disease requires the assessment of vitamin K nutritional status in population and clinical studies. This is primarily accomplished using dietary questionnaires and/or biomarkers. Because food composition databases in the US are most complete for phylloquinone (vitamin K1, the primary form in Western diets), emphasis has been on phylloquinone intakes and associations with chronic diseases. There is growing interest in menaquinone (vitamin K2) intakes for which the food composition databases need to be expanded. Phylloquinone is commonly measured in circulation, has robust quality control schemes and changes in response to phylloquinone intake. Conversely, menaquinones are generally not detected in circulation unless large quantities are consumed. The undercarboxylated fractions of three vitamin K-dependent proteins are measurable in circulation, change in response to vitamin K supplementation and are modestly correlated. Since different vitamin K dependent proteins are implicated in different diseases the appropriate vitamin K-dependent protein biomarker depends on the outcome under study. In contrast to other nutrients, there is no single biomarker that is considered a gold-standard measure of vitamin K status. Most studies have limited volume of specimens. Strategic decisions, guided by the research question, need to be made when deciding on choice of biomarkers.

Effect of diseases on response to vitamin K antagonists

INTRODUCTION

The purpose of this review article is to summarize the literature on diseases that are documented to have an effect on response to warfarin and other VKAs.

METHODS

We searched the English literature from 1946 to September 2015 via PubMed, EMBASE, and Scopus for the effect of diseases on response vitamin K antagonists including warfarin, acenocoumarol, phenprocoumon, and fluindione.

DISCUSSION

Among many factors modifying response to VKAs, several disease states are clinically relevant. Liver disease, hyperthyroidism, and CKD are well documented to increase response to VKAs. Decompensated heart failure, fever, and diarrhea may also elevate response to VKAs, but more study is needed. Hypothyroidism is associated with decreased effect of VKAs, and obese patients will likely require higher initial doses of VKAs.

CONCLUSION

In order to minimize risks with VKAs while ensuring efficacy, clinicians must be aware of the effect of disease states when prescribing these oral anticoagulants.

Atrial fibrillation and chronic kidney disease: focus on rivaroxaban

Renal insufficiency increases the risk of stroke and bleeding in atrial fibrillation patients. Although vitamin K antagonists reduce the risk of stroke in patients with moderate renal dysfunction, this observation is less clear in patients with renal impairment. Moreover, the risk of bleeding with vitamin K antagonists increases as renal function worsens. Maintaining international normalized ratio values within therapeutic targets is more difficult in patients with renal dysfunction, and those agents may cause warfarin-related nephropathy and vascular calcification. Rivaroxaban is the only nonvitamin K oral anticoagulant with a dose specifically tested in patients with moderate renal insufficiency. Rivaroxaban is effective for the prevention of stroke in atrial fibrillation patients with moderate renal dysfunction, with a lower risk of intracranial and fatal bleeding.