Association of chronic kidney disease with atrial fibrillation among adults in the United States: REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Uric Acid Level and Prevalence of Atrial Fibrillation in a Japanese General Population of 285,882

BACKGROUND

The association between serum uric acid (UA) levels and atrial fibrillation (AF) in the general population in Japan is not well known.

METHODS AND RESULTS

In total, 285,882 consecutive subjects (men, 130,897; women, 154,985; age, 58±15 years) not receiving treatment for hyperuricemia who underwent health checkups were enrolled. Subjects were stratified into deciles according to age, body mass index, estimated glomerular filtration rate, systolic blood pressure, and UA level. AF prevalence was calculated for each decile. The odds ratio that defined the decile with the lowest AF prevalence as reference was calculated in each sex. In men, the mean UA was 6.0±1.4 mg/dl; AF prevalence was 1.8% and was lowest in the decile with UA 4.4-4.9 mg/dl. Deciles with both high and low UA (5.4-5.6 mg/dl to >7.8 mg/dl and <4.3 mg/dl) were associated with significantly higher AF prevalence. In women, the mean UA was 4.5±1.1 mg/dl; AF prevalence was 0.7% and was lowest in the decile with UA 3.6-3.8 mg/dl. Deciles with highest UA (5.0-5.2 mg/dl to >5.9 mg/dl) were associated with significantly higher AF prevalence. The analysis adjusted for other clinical covariates demonstrated an independent association between UA and AF in both sexes.

CONCLUSIONS

In a representative Japanese general population, UA level was significantly associated with AF, independently of other cardiovascular risk factors. (Circ J 2016; 80: 2453-2459).

Use of Oral Anticoagulation in the Management of Atrial Fibrillation in Patients with ESRD: Pro

Warfarin has had a thin margin of benefit over risk for the prevention of stroke and systemic embolism in patients with ESRD because of higher bleeding risks and complications of therapy. The successful use of warfarin has been dependent on the selection of patients with nonvalvular atrial fibrillation at relatively high risk of stroke and systemic embolism and lower risks of bleeding over the course of therapy. Without such selection strategies, broad use of warfarin has not proven to be beneficial to the broad population of patients with ESRD and nonvalvular atrial fibrillation. In a recent meta-analysis of use of warfarin in patients with nonvalvular atrial fibrillation and ESRD, warfarin had no effect on the risks of stroke (hazard ratio, 1.12; 95% confidence interval, 0.69 to 1.82; P=0.65) or mortality (hazard ratio, 0.96; 95% confidence interval, 0.81 to 1.13; P=0.60) but was associated with increased risk of major bleeding (hazard ratio, 1.30; 95% confidence interval, 1.08 to 1.56; P<0.01). In pivotal trials, novel oral anticoagulants were generally at least equal to warfarin for efficacy and safety in nonvalvular atrial fibrillation and mild to moderate renal impairment. Clinical data for ESRD are limited, because pivotal trials excluded such patients. Given the very high risk of stroke and systemic embolism and the early evidence of acceptable safety profiles of novel oral anticoagulants, we think that patients with ESRD should be considered for treatment with chronic anticoagulation provided that there is an acceptable bleeding profile. Apixaban is currently indicated in ESRD for this application and may be preferable to warfarin given the body of evidence for warfarin and its difficulty of use and attendant adverse events.

Prescribing of Direct Oral Anticoagulants in Atrial Fibrillation Based on Estimation of Renal Function Using Standard and Modified Cockcroft-Gault Equations: A Retrospective Analysis

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Estimated glomerular filtration rate within the normal or mildly impaired range and incident non-valvular atrial fibrillation: Results from a population-based cohort study

Background Lower estimated glomerular filtration rate, in particular in the significant renal impairment range (estimated glomerular filtration rate <60 ml/min/1.73 m²), is associated with incident atrial fibrillation. This association is less established within the normal or mildly impaired estimated glomerular filtration rate range. Methods Using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rate formula, we identified ambulatory adults (>22 years old) without rheumatic heart disease or prosthetic valves and with 60 ml/min/1.73 m²<estimated glomerular filtration rate<130 ml/min/1.73 m² in their index visit, for incident, newly-diagnosed atrial fibrillation. We analyzed cohorts with and without prior cardiovascular disease. Results Over a mean follow-up of 104 months and >10 m patient-years of follow-up (∼75% <60 years old, ∼57% females), >65,000 individuals had ≥1 atrial fibrillation event (incident atrial fibrillation rate 5.1% and 5.8% excluding or including prior cardiovascular disease, or 49 and 55 per 10,000 patient-years, respectively). In both cohorts, individuals with versus without incident atrial fibrillation had lower mean estimated glomerular filtration rate (∼83 versus 95 ml/min/1.73 m²). Adjusting for age, gender, hypertension, and diabetes mellitus, overall a 10 ml/min/1.73 m² decrease in estimated glomerular filtration rate was independently associated with a mean increase in incident atrial fibrillation of 1.5% and 2.4% in the cohorts excluding or including prior cardiovascular disease, respectively ( p < 0.001 for both). However, a graded association between lower estimated glomerular filtration rate and atrial fibrillation was observed in the 90-130 ml/min/1.73 m² range, whereas a blunted association was observed in the 60-90 ml/min/1.73 m² range. Conclusion Within the 60 ml/min/1.73 m²< estimated glomerular filtration rate < 130 ml/min/1.73 m² range, lower estimated glomerular filtration rate is independently associated with incident non-valvular atrial fibrillation in adults without prior atrial fibrillation, mainly attributed to a graded association within the 90-130 ml/min/1.73 m² range.

Renal Impairment and Cardiovascular Disease in HIV-Positive Individuals: The D:A:D Study

BACKGROUND

While the association between renal impairment and cardiovascular disease (CVD) is well established in the general population, the association remains poorly understood in human immunodeficiency virus (HIV)-positive individuals.

METHODS

Individuals with ≥2 estimated glomerular filtration rate (eGFR) measurements after 1 February 2004 were followed until CVD, death, last visit plus 6 months, or 1 February 2015. CVD was defined as the occurrence of centrally validated myocardial infarction, stroke, invasive cardiovascular procedures, or sudden cardiac death.

RESULTS

During a median follow-up duration of 8.0 years (interquartile range, 5.4-8.9 years) 1357 of 35 357 individuals developed CVD (incidence rate, 5.2 cases/1000 person-years [95% confidence interval {CI}, 5.0-5.5]). Confirmed baseline eGFR and CVD were closely related with 1.8% of individuals (95% CI, 1.6%-2.0%) with an eGFR > 90 mL/minute/1.73 m(2) estimated to develop CVD at 5 years, increasing to 21.1% (95% CI, 6.6%-35.6%) among those with an eGFR ≤ 30 mL/minute/1.73 m(2) The strong univariate relationship between low current eGFR and CVD was primarily explained by increasing age in adjusted analyses, although all eGFRs ≤ 80 mL/minute/1.73 m(2) remained associated with 30%-40% increased CVD rates, and particularly high CVD rates among individuals with an eGFR ≤ 30 mL/minute/1.73 m(2) (incidence rate ratio, 3.08 [95% CI, 2.04-4.65]).

CONCLUSIONS

Among HIV-positive individuals in a large contemporary cohort, a strong relation between confirmed impaired eGFR and CVD was observed. This finding highlights the need for renal preventive measures and intensified monitoring for emerging CVD, particularly in older individuals with continuously low eGFRs.

Increased risk of atrial fibrillation in end-stage renal disease patients on dialysis: A nationwide, population-based study in Taiwan

End-stage renal disease (ESRD) patients commonly have a higher risk of developing cardiovascular diseases than general population. Chronic kidney disease is an independent risk factor for atrial fibrillation (AF); however, little is known about the AF risk among ESRD patients with various modalities of renal replacement therapy. We used the Taiwan National Health Insurance Research Database to determine the incident AF among peritoneal dialysis (PD) and hemodialysis (HD) patients in Taiwan.Our ESRD cohort include Taiwan National Health Insurance Research Database, we identified 15,947 patients, who started renal replacement therapy between January 1, 2002 and December 31, 2003. From the same data source, 47,841 controls without ESRD (3 subjects for each patient) were identified randomly and frequency matched by gender, age (±1 year), and the year of the study patient's index date for ESRD between January 1, 2002 and December 31, 2003.During the follow-up period (mean duration: 8-10 years), 3428 individuals developed the new-onset AF. The incidence rate ratios for AF were 2.07 (95% confidence interval [CI] = 1.93-2.23) and 1.78 (95% CI = 1.30-2.44) in HD and PD groups, respectively. After we adjusted for age, gender, and comorbidities, the hazard ratios for the AF risk were 1.46 (95% CI = 1.32-1.61) and 1.32 (95% CI = 1.00-1.83) in HD and PD groups, respectively. ESRD patients with a history of certain comorbidities including hypertension, diabetes mellitus, hyperlipidemia, coronary artery disease, heart failure, valvular heart disease, and chronic obstructive pulmonary disease (COPD) have significantly increased risks of AF.This nationwide, population-based study suggests that incidence of AF is increased among dialysis ESRD patients. Furthermore, we have to pay more attention in clinical practice and long-term care for those ESRD patients with a history of certain comorbidities.

Impact of moderate to severe renal impairment on long-term clinical outcomes in patients with atrial fibrillation

BACKGROUND

The deleterious effect of renal impairment in non-valvular atrial fibrillation (AF) patients has recently been reported. We investigated the impact of moderate to severe renal impairment on long-term clinical outcomes in AF patients.

METHODS

A total of 2126 AF patients were enrolled and divided into two groups according to ≥ or <60mL/min estimated glomerular filtration rate (eGFR). Clinical outcomes including all-cause death, cardiac death, ischemic stroke (IS), bleeding, and admission for heart failure (HF) were analyzed.

RESULTS

Compared to the ≥60mL/min eGFR group, <60mL/min eGFR patients were older; had a higher proportion of females; were more likely to have diabetes, hypertension, and history of stroke; and had higher CHADS₂, CHA₂DS₂-VAS_c, and HAS-BLED scores. During the follow-up period (median 6.23 years), all-cause death, bleeding, admission for HF, and progression to persistent or permanent AF were significantly increased in the <60mL/min eGFR group compared to the ≥60mL/min eGFR group. After multivariate Cox regression analyses, <60mL/min eGFR increased the risk of all-cause death [hazard ratio (HR): 1.84; 95% confidence interval (CI): 1.03-3.28, p=0.04] and bleeding (HR: 1.28; 95% CI: 1.04-1.57, p=0.02). IS was only significantly increased in the <60mL/min eGFR group not receiving antithrombotic treatment.

CONCLUSION

Moderate to severe renal impairment is a poor prognostic factor of long-term clinical outcomes in AF patients.

Assessment of the Risk Factors and Outcomes for Postoperative Atrial Fibrillation Patients Undergoing Isolated Coronary Artery Bypass Grafting

BACKGROUND

Atrial fibrillation is the most common complication of cardiac surgery and is associated with significant morbidity and mortality. Recognizing patients at high risk for developing postoperative atrial fibrillation (POAF) may help identify those who could benefit from strategies to prevent POAF. This study was conducted to delineate outcomes and to assess risk factors for POAF among Taiwanese patients undergoing coronary artery bypass grafting (CABG).

METHODS

From January 2009 until February 2012, this prospective study included 266 consecutive patients admitted to our hospital with coronary artery disease. All patients underwent isolated CABG. Patients with preoperative permanent atrial fibrillation and concomitant surgery were excluded. Multiple risk factors associated with the incidence of POAF were collected and evaluated.

RESULTS

POAF occurred in 126 of 226 patients (47.37%). Univariate analysis revealed that significant risk factors for the condition were age, gender, diabetes, dyslipidemia, smoking, impaired renal function, impaired cardiac function, and increased serum electrolytes. Multivariate analysis showed dyslipidemia [hazard ratio (HR): 0.418; 95% confidence interval (Cl): 0.190-0.915, p = 0.029], impaired renal function as indicated by an estimated glomerular filtration rate < 60 mL/min/1.73 m(2) (HR: 3.174; 95% CI: 1.432-7.037, p = 0.004), and serum sodium (HR: 1.112; 95% Cl: 1.047-1.182, p = 0.001) prior to cardiopulmonary bypass as significant. Moreover, POAF was associated with lower 30-day, 1- and 3-year cumulative survival rates and higher early postoperative complications.

CONCLUSIONS

Patients with isolated CABG who were administered β-blockers, angiotensin converting enzyme inhibitor/angiotensin receptor blockers treatment, and lipid therapy before CABG were associated with reduced POAF, while those with impaired renal function and higher serum sodium before CABG predisposed POAF in a Taiwanese population.

KEY WORDS

Atrial fibrillation (AF); Coronary artery bypass grafting (CABG); Coronary artery disease (CAD); Postoperative atrial fibrillation (POAF).

Atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac rhythm disorder, and increases in prevalence with increasing age and the number of cardiovascular comorbidities. AF is characterized by a rapid and irregular heartbeat that can be asymptomatic or lead to symptoms such as palpitations, dyspnoea and dizziness. The condition can also be associated with serious complications, including an increased risk of stroke. Important recent developments in the clinical epidemiology and management of AF have informed our approach to this arrhythmia. This Primer provides a comprehensive overview of AF, including its epidemiology, mechanisms and pathophysiology, diagnosis, screening, prevention and management. Management strategies, including stroke prevention, rate control and rhythm control, are considered. We also address quality of life issues and provide an outlook on future developments and ongoing clinical trials in managing this common arrhythmia.

Cardiovascular Pharmacogenomics--Implications for Patients With CKD

CKD is an independent risk factor for cardiovascular disease (CVD). Thus, patients with CKD often require treatment with cardiovascular drugs, such as antiplatelet, antihypertensive, anticoagulant, and lipid-lowering agents. There is significant interpatient variability in response to cardiovascular therapies, which contributes to risk for treatment failure or adverse drug effects. Pharmacogenomics offers the potential to optimize cardiovascular pharmacotherapy and improve outcomes in patients with CVD, although data in patients with concomitant CKD are limited. The drugs with the most pharmacogenomic evidence are warfarin, clopidogrel, and statins. There are also accumulating data for genetic contributions to β-blocker response. Guidelines are now available to assist with applying pharmacogenetic test results to optimize warfarin dosing, selection of antiplatelet therapy after percutaneous coronary intervention, and prediction of risk for statin-induced myopathy. Clinical data, such as age, body size, and kidney function have long been used to optimize drug prescribing. An increasing number of institutions are also implementing genetic testing to be considered in the context of important clinical factors to further personalize drug therapy for patients with CVD.

Interleukin-6 Is a Risk Factor for Atrial Fibrillation in Chronic Kidney Disease: Findings from the CRIC Study

Atrial fibrillation (AF) is the most common sustained arrhythmia in patients with chronic kidney disease (CKD). In this study, we examined the association between inflammation and AF in 3,762 adults with CKD, enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study. AF was determined at baseline by self-report and electrocardiogram (ECG). Plasma concentrations of interleukin(IL)-1, IL-1 Receptor antagonist, IL-6, tumor necrosis factor (TNF)-α, transforming growth factor-β, high sensitivity C-Reactive protein, and fibrinogen, measured at baseline. At baseline, 642 subjects had history of AF, but only 44 had AF in ECG recording. During a mean follow-up of 3.7 years, 108 subjects developed new-onset AF. There was no significant association between inflammatory biomarkers and past history of AF. After adjustment for demographic characteristics, comorbid conditions, laboratory values, echocardiographic variables, and medication use, plasma IL-6 level was significantly associated with presence of AF at baseline (Odds ratio [OR], 1.61; 95% confidence interval [CI], 1.21 to 2.14; P = 0.001) and new-onset AF (OR, 1.25; 95% CI, 1.02 to 1.53; P = 0.03). To summarize, plasma IL-6 level is an independent and consistent predictor of AF in patients with CKD.

Comparison between CHA2DS2-VASc and the new R2CHADS2 and ATRIA scores at predicting thromboembolic event in non-anticoagulated and anticoagulated patients with non-valvular atrial fibrillation

Background

Accurate risk stratification is considered the first and most important step in the management of patients with non-valvular atrial fibrillation (NVAF). We compared the performance of the widely used CHA₂DS₂-VASc and the recently developed R₂CHADS₂ and ATRIA scores, for predicting thromboembolic (TE) event in either non-anticoagulated or anticoagulated patients with NVAF.

Methods

The non-anticoagulated cohort was comprised of 154 patients, whereas 911 patients formed the cohort of patients on vitamin-K-antagonist. The scores were computed using the criteria mentioned in their developmental cohorts. Measures of performance for the risk scores were evaluated at predicting TE event.

Results

In the non-anticoagulated cohort, 9 TE events occurred during 11 ± 2.7 months. CHA₂DS₂-VASc showed significant association with TE occurrence: hazard ratio (HR) = 1.58 (95 % confidence interval [95 % IC] 1.01–2.46), but R₂CHADS₂ and ATRIA did not (HR = 1.23 (95 % CI 0.86–1.77) and 1.20 (95 % CI 0.93–1.56), respectively.

In the anticoagulated cohort, after 10 ± 3 months of follow up, 18 TE events were developed. In that cohort, the three scores showed similar association with TE risk: HR = 1.49 (95 % CI 1.13–1.97), 1.41 (95 % CI 1.13–1.77) and 1.37 (95 % CI 1.12–1.66) for CHA₂DS₂-VASc, R₂CHADS₂ and ATRIA, respectively.

In both cohorts, no TE event occurred in patients classified in the low risk category according to CHA₂DS₂-VASc or R₂CHADS₂.

Conclusions

In this study of NVAF patients, CHA₂DS₂-VASc has better association with TE events than the new R₂CHADS₂ and ATRIA risk scores in the non-anticoagulated cohort. CHA₂DS₂-VASc and R₂CHADS₂ can identify patients at truly low risk regardless of the anticoagulation status.

Incidence and 1-Year Outcomes of Perioperative Atrial Arrhythmia in Elderly Adults After Hip Fracture Surgery

OBJECTIVES

To determine the incidence and 1-year outcomes of an elderly population with perioperative atrial arrhythmia (PAA) within 7 days of hip fracture surgery.

DESIGN

Retrospective cohort study.

SETTING

The Rochester Epidemiology Project (REP).

PARTICIPANTS

Elderly adults consecutive undergoing hip fracture repair from 1988 to 2002 in Olmsted County, Minnesota (N = 1,088, mean age 84.0 ± 7.4, 80.2% female).

MEASUREMENTS

Baseline clinical variables were analyzed in relation to survival using Cox proportional hazards methods for comparison.

RESULTS

Sixty-one participants (5.6%) developed PAA within the first 7 days. During 1 year of follow-up, 239 (22%) participants died. PAA was associated with greater mortality (45% vs 21%; hazard ratio (HR) = 2.8, 95% confidence interval (CI) = 1.9-4.2). Other mortality risk factors were male sex (HR = 2.0, 95% CI = 1.5-2.6), congestive heart failure (HR = 2.1, 95% CI = 1.7-2.8), chronic renal insufficiency (HR = 2.0, 95% CI = 1.5-2.8), dementia (HR = 2.9, 95% CI = 2.2-3.7), and American Society of Anesthesiologists risk Class III, IV, or V (HR = 3.3, 95% CI = 1.9-5.9).

CONCLUSION

Elderly adults undergoing hip fracture surgery who develop PAA within 7 days have significantly higher 1-year mortality than those who do not. Further studies are indicated to determine whether prevention of PAA will reduce mortality in this population.

Renal function assessment in atrial fibrillation: Usefulness of chronic kidney disease epidemiology collaboration vs re-expressed 4 variable modification of diet in renal disease

AIM: To compare the performance of the re-expressed Modification of Diet in Renal Disease equation vs the new Chronic Kidney Disease Epidemiology Collaboration equation in patients with non-valvular atrial fibrillation.

METHODS: We studied 911 consecutive patients with non-valvular atrial fibrillation on vitamin-K antagonist. The performance of the re-expressed Modification of Diet in Renal Disease equation vs the new Chronic Kidney Disease Epidemiology Collaboration equation in patients with non-valvular atrial fibrillation with respect to either a composite endpoint of major bleeding, thromboembolic events and all-cause mortality or each individual component of the composite endpoint was assessed using continuous and categorical ≥ 60, 59-30, and < 30 mL/min per 1.73 m² estimated glomerular filtration rate.

RESULTS: During 10 ± 3 mo, the composite endpoint occurred in 98 (10.8%) patients: 30 patients developed major bleeding, 18 had thromboembolic events, and 60 died. The new equation provided lower prevalence of renal dysfunction < 60 mL/min per 1.73 m² (32.9%), compared with the re-expressed equation (34.1%). Estimated glomerular filtration rate from both equations was independent predictor of composite endpoint (HR = 0.98 and 0.97 for the re-expressed and the new equation, respectively; P < 0.0001) and all-cause mortality (HR = 0.98 for both equations, P < 0.01). Strong association with thromboembolic events was observed only when estimated glomerular filtration rate was < 30 mL/min per 1.73 m²: HR is 5.1 for the re-expressed equation, and HR = 5.0 for the new equation. No significant association with major bleeding was observed for both equations.

CONCLUSION: The new equation reduced the prevalence of renal dysfunction. Both equations performed similarly in predicting major adverse outcomes.

Role of Indoxyl Sulfate as a Predisposing Factor for Atrial Fibrillation in Renal Dysfunction

Background

Renal dysfunction is a major risk factor for atrial fibrillation (AF). The uremic toxin indoxyl sulfate may contribute to the progression of cardiac fibrosis and AF substrate in renal dysfunction.

Methods and Results

Male Sprague–Dawley rats were assigned randomly to the following groups: 5/6 nephrectomy (5/6Nx) with vehicle, 5/6Nx with AST‐120, sham procedure with vehicle, and sham procedure with AST‐120. Vehicle and AST‐120 were administered for 4 weeks. Serum levels of IS were significantly increased in 5/6Nx groups. Expression of malondialdehyde, an indicator of oxidative stress, was upregulated in the left atrium of 5/6Nx groups and was accompanied by an increase in expression of NADPH oxidase 2 and 4. Monocyte‐mediated inflammatory signals such as CD68, monocyte chemoattractant protein 1, and vascular cell adhesion molecule 1 were also upregulated in 5/6Nx groups. Interstitial fibrosis was promoted heterogeneously, and expression of profibrotic indicators such as transforming growth factor β1, α‐smooth muscle actin, and collagen type 1 was upregulated in left atrium tissue of 5/6Nx groups. In cultured atrial fibroblasts, incubation with IS upregulated expression of the markers of oxidative stress, inflammation, and profibrotic factors. These results suggest the direct effects of IS on the progression of AF substrate. AF was consistently and invariably induced by atrial extrastimuli in 5/6Nx groups in electrophysiological experiments. AST‐120 treatment significantly alleviated renal dysfunction–induced oxidative stress, inflammation, and atrial fibrosis and, consequently, attenuated AF inducibility.

Conclusions

Indoxyl sulfate facilitates atrial fibrosis and AF and thus is a novel therapeutic target for prevention of renal dysfunction–induced AF.

Stroke prevention in the elderly atrial fibrillation patient with comorbid conditions: focus on non-vitamin K antagonist oral anticoagulants

Stroke prevention in elderly atrial fibrillation patients remains a challenge. There is a high risk of stroke and systemic thromboembolism but also a high risk of bleeding if anticoagulants are prescribed. The elderly have increased chronic kidney disease, coronary artery disease, polypharmacy, and overall frailty. For all these reasons, anticoagulant use is underutilized in the elderly. In this manuscript, the benefits of non-vitamin K antagonist oral anticoagulants compared with warfarin in the elderly patient population with multiple comorbid conditions are reviewed.

Trends in hospitalization for atrial fibrillation: epidemiology, cost, and implications for the future

Atrial fibrillation (AF) is the most prevalent arrhythmia worldwide and the most common arrhythmia leading to hospitalization. Due to a substantial increase in incidence and prevalence of AF over the past few decades, it attributes to an extensive economic and public health burden. The increasing number of hospitalizations, aging population, anticoagulation management, and increasing trend for disposition to a skilled facility are drivers of the increasing cost associated with AF. There has been significant progress in AF management with the release of new oral anticoagulants, use of left atrial catheter ablation, and novel techniques for left atrial appendage closure. In this article, we aim to review the trends in epidemiology, hospitalization, and cost of AF along with its future implications on public health.

Risk of Ischemic Stroke and Stroke Prevention in Patients with Atrial Fibrillation and Renal Dysfunction

Chronic kidney disease (CKD) has been identified as an important risk factor for new-onset atrial fibrillation (AF) and would significantly increase the risk of AF-related strokes. Stroke prevention in AF patients with CKD is a big challenge, especially for patients with end-stage renal disease (ESRD) undergoing long-term dialysis. In addition to an increase risk of stroke, renal dysfunction was also associated with a higher risk of hemorrhage due to dysregulation of coagulation and uremia-mediated platelet dysfunction. Therefore, the net clinical benefit balancing stroke risk reduction and increased risk of bleeding should be weighed carefully before initiating oral anti-coagulants for ESRD patients. Several studies investigating whether warfarin should be used for stroke prevention in AF patients with ESRD have been published and showed inconsistent results. Since none of these studies was a prospective and randomized trial, the best strategy for stroke prevention in AF patients with ESRD undergoing dialysis remained unknown and more data are necessary to answer this issue.

Renal Impairment and Prognosis of Patients with Atrial Fibrillation Undergoing Coronary Intervention - The AFCAS Trial

BACKGROUND

Renal impairment is a well-known risk factor for cardiovascular complications, but the effect of different stages of renal impairment on thrombotic/thromboembolic and bleeding complications in patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI) remains largely unknown. We sought to evaluate the incidence and clinical impact of four stages of renal impairment in patients with AF undergoing PCI.

METHODS

We assessed renal function by estimated glomerular filtration rate (eGFR) and outcomes in 781 AF patients undergoing PCI by using the data from a prospective European multicenter registry. End-points included all-cause mortality, major adverse cardiac and cerebrovascular events (MACCE) and bleeding events at 12 months.

RESULTS

A total of 195 (25%) patients had normal renal function (eGFR ≥90 mL/min), 290 (37%) mild renal impairment (eGFR 60-89), 263 (34%) moderate renal impairment (eGFR 30-59) and 33 (4%) severe renal impairment (eGFR <30). Degree of renal impairment remained an independent predictor of mortality and MACCE in an adjusted a Cox regression model. Even patients with mild renal impairment had a higher risk of all-cause mortality (HR 2.25, 95%CI 1.02-4.98, p=0.04) and borderline risk for MACCE (HR 1.56, 95%CI 0.98- 2.50, p=0.06) compared to those with normal renal function.

CONCLUSIONS

Renal impairment is common in patients with AF undergoing PCI and even mild renal impairment has an adverse prognostic effect in these patients requiring multiple antithrombotic medications.

Coronary heart disease risk factors and outcomes in the twenty-first century: findings from the REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

REasons for Geographic and Racial Differences in Stroke (REGARDS) is a longitudinal study supported by the National Institutes of Health to determine the disparities in stroke-related mortality across USA. REGARDS has published a body of work designed to understand the disparities in prevalence, awareness, treatment, and control of coronary heart disease (CHD) and its risk factors in a biracial national cohort. REGARDS has focused on racial and geographical disparities in the quality and access to health care, the influence of lack of medical insurance, and has attempted to contrast current guidelines in lipid lowering for secondary prevention in a nationwide cohort. It has described CHD risk from nontraditional risk factors such as chronic kidney disease, atrial fibrillation, and inflammation (i.e., high-sensitivity C-reactive protein) and has also assessed the role of depression, psychosocial, environmental, and lifestyle factors in CHD risk with emphasis on risk factor modification and ideal lifestyle factors. REGARDS has examined the utility of various methodologies, e.g., the process of medical record adjudication, proxy-based cause of death, and use of claim-based algorithms to determine CHD risk. Some valuable insight into less well-studied concepts such as the reliability of current troponin assays to identify "microsize infarcts," caregiving stress, and CHD, heart failure, and cognitive decline have also emerged. In this review, we discuss some of the most important findings from REGARDS in the context of the existing literature in an effort to identify gaps and directions for further research.

Atrial fibrillation and incident end-stage renal disease: The REasons for Geographic And Racial Differences in Stroke (REGARDS) study

INTRODUCTION

Atrial fibrillation (AF) is an independent risk factor for end-stage renal disease (ESRD) among persons with chronic kidney disease (CKD), however, the association between AF and incident ESRD has not been examined in the general United States population.

METHODS

A total of 24,953 participants (mean age 65 ± 9.0 years; 54% women; 40% blacks) from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study were included in this analysis. AF was identified at baseline (2003-2007) from electrocardiogram data and self-reported history. Incident cases of ESRD were identified through linkage with the United States Renal Data System. Cox proportional-hazards regression was used to compute hazard ratios (HR) and 95% confidence intervals (CI) for the association between AF and incident ESRD.

RESULTS

A total of 2,155 (8.6%) participants had AF at baseline. Over a median follow-up of 7.4 years, 295 (1.2%) persons developed ESRD. In a model adjusted for demographics and potential confounders, AF was associated with an increased risk of incident ESRD (HR=1.51, 95% CI=1.08, 2.11). The association between AF and ESRD became non-significant after further adjustment for CKD markers (eGFR <60 mL/min/1.73 m(2) and urine albumin-to-creatinine ratio ≥ 30 mg/dL) (HR=1.24, 95% CI=0.89, 1.73).

CONCLUSION

AF is associated with an increased risk of ESRD in the general United States population and this association potentially is explained by underlying CKD.

Relation of contrast induced nephropathy to new onset atrial fibrillation in acute coronary syndrome

Chronic renal failure has been described as a risk factor for the development of atrial fibrillation (AF). The aim of this study was to examine the association between contrast-induced nephropathy (CIN) and new-onset AF in patients with acute coronary syndromes. A total of 1,520 consecutive patients (mean age 67.1 ± 12.7 years) with acute coronary syndromes (34.4% with ST-segment elevation myocardial infarctions) who underwent coronary angiography were studied. CIN was defined as an increase in serum creatinine of 0.5 mg/dl within 72 hours of contrast exposure. The independent effect of AF history (chronic or paroxysmal AF before catheterization) on the development of CIN, as well as the independent effect of CIN on the development of new-onset AF (after catheterization, during the in-hospital phase), were tested by using different logistic regression models. One hundred thirty-nine patients (9.1%) had histories of AF before catheterization (60 with paroxysmal and 79 with chronic AF), and 56 (4.1%) developed new-onset AF after catheterization. Eighty-seven patients (5.7%) had CIN. AF history was a predictor of CIN in univariate analysis (odds ratio 2.19, 95% confidence interval 1.22 to 3.95, p = 0.007) but not in multivariate analysis, after adjusting for confounding variables (odds ratio 1.69, 95% confidence interval 0.89 to 3.22, p = 0.111). In contrast, those with CIN had an increased prevalence of new-onset AF (15.3% vs 3.4%, p <0.001). After adjusting for those variables associated with new-onset AF in the univariate analysis, CIN continued to show a significant association with new-onset AF, with a twofold increased risk (odds ratio 2.45, 95% confidence interval 1.07 to 5.64, p = 0.035). In conclusion, the development of CIN is an independent predictor of new-onset AF in the context of acute coronary syndromes.

Advanced chronic kidney disease in non-valvular atrial fibrillation: extending the utility of R2CHADS2 to patients with advanced renal failure

BACKGROUND

The R2CHADS2 is a new prediction rule for stroke risk in atrial fibrillation (AF) patients wherein R stands for renal risk. However, it was created from a cohort that excluded patients with advanced renal failure (defined as glomerular filtration rate of <30 mL/min). Our study extends the use of R2CHADS2 to patients with advanced renal failure and aims to compare its predictive power against the currently used CHADS and CHA2DS2VaSc.

METHODS

This retrospective cohort study analyzed the 1-year risk for stroke of the 524 patients with AF at Metropolitan Hospital Center. AUC and C statistics were calculated using three groups: (i) the entire cohort including patients with advanced renal failure, (ii) a cohort excluding patients with advanced renal failure and (iii) all patients with GFR < 30 mL/min only.

RESULTS

R2CHADS2, as a predictor for stroke risk, consistently performs better than CHADS2 and CHA2DS2VsC in groups 1 and 2. The C-statistic was highest in R2CHADS compared with CHADS or CHADSVASC in group 1 (0.718 versus 0.605 versus 0.602) and in group 2 (0.724 versus 0.584 versus 0.579). However, there was no statistically significant difference in group 3 (0.631 versus 0.629 versus 0.623).

CONCLUSION

Our study supports the utility of R2CHADS2 as a clinical prediction rule for stroke risk in patients with advanced renal failure.

Intersection of cardiovascular disease and kidney disease: atrial fibrillation

PURPOSE OF REVIEW

Atrial fibrillation is the most common sustained arrhythmia in patients with kidney disease. The purpose of this review is to describe the burden of atrial fibrillation in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD), postulate possible mechanisms to explain this burden of disease, understand the clinical consequences of atrial fibrillation and review the treatment options for atrial fibrillation specific to patients with kidney disease.

RECENT FINDINGS

Recent literature has revealed that the clinical multiorgan impact of atrial fibrillation in patients with CKD and ESRD is substantial. Although novel oral anticoagulants to treat atrial fibrillation and prevent associated complications have been tested in large trials in the general population, there is a paucity of data on the efficacy and safety of these agents in patients with advanced CKD and ESRD.

SUMMARY

Atrial fibrillation is a significant comorbidity in patients with CKD and ESRD with important prognostic implications. More research is needed to understand the mechanisms that contribute to the disproportionate burden of this arrhythmia in patients with kidney disease and in to treatment options specific to this population of high-risk patients.

Incident atrial fibrillation and risk of death in adults with chronic kidney disease

Background

Atrial fibrillation (AF) frequently occurs in patients with chronic kidney disease (CKD); however, the long‐term impact of development of AF on the risk of death among patients with CKD is unknown.

Methods and Results

We studied adults with CKD (glomerular filtration rate <60 mL/min per 1.73 m² by the Chronic Kidney Disease Epidemiology Collaboration equation) identified between 2002 and 2010 who were enrolled in Kaiser Permanente Northern California and had no previously documented AF. Incident AF was identified using primary hospital discharge diagnoses or ≥2 outpatient visits for AF. Death was comprehensively ascertained from health plan administrative databases, Social Security Administration vital status files, and the California death certificate registry. Covariates included demographics, comorbidity, ambulatory blood pressure, laboratory values (hemoglobin, proteinuria), and longitudinal medication use. Among 81 088 adults with CKD, 6269 (7.7%) developed clinically recognized incident AF during a mean follow‐up of 4.8±2.7 years. There were 2388 cases of death that occurred after incident AF (145 per 1000 person‐years) compared with 18 865 cases of death during periods without AF (51 per 1000 person‐years, P<0.001). After adjustment for potential confounders, incident AF was associated with a 66% increase in relative rate of death (adjusted hazard ratio 1.66, 95% CI 1.57 to 1.77).

Conclusion

Incident AF is independently associated with an increased risk of death in adults with CKD. Further study is needed to understand the mechanisms by which CKD is associated with AF and to identify potentially modifiable risk factors to decrease the burden of AF and subsequent risk of death in this high‐risk population.

FGF-23 dysregulates calcium homeostasis and electrophysiological properties in HL-1 atrial cells

BACKGROUND

Fibroblast growth factor (FGF)-23 is a key regulator of phosphate homeostasis. Higher FGF-23 levels are correlated with poor outcomes in cardiovascular diseases. FGF-23 can produce cardiac hypertrophy and increase intracellular calcium, which can change cardiac electrical activity. However, it is not clear whether FGF-23 possesses arrhythmogenic potential through calcium dysregulation. Therefore, the purposes of this study were to evaluate the electrophysiological effects of FGF-23 and identify the underlying mechanisms.

METHODS

Patch clamp, confocal microscope with Fluo-4 fluorescence, and Western blot analyses were used to evaluate the electrophysiological characteristics, calcium homeostasis and calcium regulatory proteins in HL-1 atrial myocytes with and without FGF-23 (10 and 25 ng/mL) incubation for 24 h.

RESULTS

FGF-23 (25 ng/mL) increased L-type calcium currents, calcium transient and sarcoplasmic reticulum Ca(2+) contents in HL-1 cells. FGF-23 (25 ng/mL)-treated cells (n = 14) had greater incidences (57%, 17% and 15%, P < 0·05) of delayed afterdepolarizations than control (n = 12) and FGF-23 (10 ng/mL)-treated cells (n = 13). Compared with control cells, FGF-23 (25 ng/mL)-treated cells (n = 14) exhibited increased phosphorylation of calcium/calmodulin-dependent protein kinase IIδ and phospholamban (PLB) at threonine 17 but had similar phosphorylation extents of PLB at serine 16, total PLB and sarcoplasmic reticulum Ca(2+) -ATPase protein. Moreover, the FGF receptor inhibitor (PD173074, 10 nM), calmodulin inhibitor (W7, 5 μM) and phospholipase C inhibitor (U73122, 1 μM) attenuated the effects of FGF-23 on calcium/calmodulin-dependent protein kinase II phosphorylation.

CONCLUSIONS

FGF-23 increases HL-1 cells arrhythmogenesis with calcium dysregulation through modulating calcium-handling proteins.

Renal function, attributes and coagulation treatment in atrial fibrillation (R-FACT Study): retrospective, observational, longitudinal cohort study of renal function and antithrombotic treatment patterns in atrial fibrillation patients with documented eGFR in real-world clinical practices in Germany

AIMS

This retrospective, observational, longitudinal study aimed to document the distribution, changes in renal function [measured by estimated glomerular filtration (eGFR)] and antithrombotic treatment pattern in atrial fibrillation (AF) patients in real-world settings managed by general practitioners in Germany.

METHODS AND RESULTS

Data were extracted from the German Longitudinal Patient Database. A total of 15,900 patients with AF were identified. Among 1660 having eGFR available at baseline, 3.4% had severely impaired eGFR, 9.7% and 25.6% had moderate severe decrease and moderate decrease in eGFR, respectively, and 61.3% had mildly decreased/normal eGFR. Patients with moderately and severely decreased eGFR tended to be older. The proportion of patients with a CHADS2 score ≥ 2 was 92.9% in those with severely decreased eGFR, and 87.0% and 79.1% in those with moderately severe and moderately decreased eGFR. During follow up, 52.1% of patients with severely decreased eGFR, and 26.3% to 23.7% of patients with moderately decreased eGFR were not treated by antithrombotic. When comparing baseline with follow-up eGFR, 55.0% of patients showed decreased eGFR. Age, diabetes, dyslipidaemia and history of myocardial infarction were identified as significant predictors for renal function deterioration based on results from multivariate Cox regression model.

CONCLUSIONS

Moderate-to-severe renal dysfunction is prevalent (~38%) in German AF patients with documented eGFR managed in actual clinical practices. The risk of stroke, as measured by the CHADS2 score, was associated with decreased renal function. Treatment with anticoagulation therapies decreased with decreasing renal function, despite increasing risk of stroke. Anticoagulation treatments remain suboptimal during the 12-month follow up in patients with moderate or severe renal impairment.

Predictors of new onset atrial fibrillation in patients with heart failure

INTRODUCTION

Stroke associated with atrial fibrillation (AF) is more frequent in heart failure. It is unknown what variables predict future AF in these patients and how AF might evolve over time. We investigated this in patients with implantable cardiac defibrillators (ICD) where AF detection is optimal.

METHODS

Single centre, retrospective, observational cohort study. All ischaemic cardiomyopathy patients with dual chamber, primary prevention ICD implants between Aug 2003 and Dec 2009 were screened and included if at implant, they had no known AF history. Nine variables were analysed. AF was defined as any atrial tachyarrhythmia ≥180 bpm and ≥30 s. Multivariable, binary logistic regression models were built by adding variables significant in the univariate models. Variables were retained in the final multivariate models if p<0.05.

RESULTS

n=197 met the inclusion criteria (85.8% male, median age: 66.8 years). After median follow-up for 2.8 years, 44.2% developed AF. After univariate analysis, the baseline variables associated with AF after implant were age, NYHA class and renal impairment (RI, defined eGFR<60 ml/min/1.73 m2) (p<0.05). After multivariable analysis, the only variable which was associated with AF was RI (HR: 2.04 (CI: 1.10-3.79)). Two baseline variables were independently associated with all-cause mortality: RI (HR: 2.42 (1.14-5.12)) and non-white ethnicity.

CONCLUSION

RI at time of implant was independently associated with both future AF and all-cause mortality during long-term follow-up. RI was a stronger predictor of AF than age. Those patients with heart failure and RI should be regularly screened for asymptomatic AF, regardless of age, to ensure that stroke prophylaxis may be initiated.

Management of Atrial Fibrillation

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

Renal disease and left atrial remodeling predict atrial fibrillation in patients with cardiovascular risk factors

OBJECTIVES

In this prospective population-based study, we tested the possible interaction between chronic kidney disease (CKD) and left atrium volume index (LAVI) in predicting incident atrial fibrillation (AF).

METHODS

We enrolled 3549 Caucasian subjects, 1829 men and 1720 women, aged 60.7 ± 10.6 years, without baseline AF and thyroid disorders. Echocardiographic left ventricular mass and LAVI were measured. Renal function was calculated by estimated glomerular filtration rate (e-GFR). To test the effect of some clinical confounders on incident AF, we constructed different models including clinical and laboratory parameters. AF diagnosis was made by standard electrocardiogram or 24-h ECG-Holter, hospital discharge diagnoses, and by the all-clinical documentation.

RESULTS

During the follow-up (53.3 ± 18.1 months), 546 subjects developed AF (4.5 events/100 patient-years). Progressors to AF were older, had a higher body mass index, blood pressure, LDL-cholesterol, glucose, cardiac mass, and LAVI, and had lower e-GFR. Hypertension, metabolic syndrome, diabetes, cardiac hypertrophy and CKD were more common among AF cases than controls. In the final Cox regression model, variables that remained significantly associated with AF were: cardiac hypertrophy (HR=1.495, 95% CI=1.215-1.841), renal disease (HR=1.528, 95% CI=1.261-1.851), age (HR=1.586, 95% CI=1.461-1.725) and LAVI (HR=2.920, 95% CI=2.426-3.515). The interaction analysis demonstrated a synergic effect between CKD and cardiac hypertrophy (HR=4.040, 95% CI=2.661-6.133), as well as between CKD and LAVI (HR=4.875, 95% CI=2.699-8.805). The coexistence of all three subclinical organ damages significantly increases the arrhythmic risk (HR=7.185, 95% CI=5.041-10.240).

CONCLUSIONS

Our data demonstrate that LAVI and CKD significantly interact in a synergic manner in increasing AF risk.

Lone atrial fibrillation - an overview

Atrial fibrillation (AF) sometimes develops in younger individuals without any evident cardiac or other disease. To refer to these patients who were considered to have a very favourable prognosis compared with other AF patients, the term 'lone' AF was introduced in 1953. However, there are numerous uncertainties associated with 'lone' AF, including inconsistent entity definitions, considerable variations in the reported prevalence and outcomes, etc. Indeed, increasing evidence suggests a number of often subtle cardiac alterations associated with apparently 'lone' AF, which may have relevant prognostic implications. Hence, 'lone' AF patients comprise a rather heterogeneous cohort, and may have largely variable risk profiles based on the presence (or absence) of overlooked subclinical cardiovascular risk factors or genetically determined subtle alterations at the cellular or molecular level. Whether the implementation of various cardiac imaging techniques, biomarkers and genetic information could improve the prediction of risk for incident AF and risk assessment of 'lone' AF patients, and influence the treatment decisions needs further research. In this review, we summarise the current knowledge on 'lone' AF, highlight the existing inconsistencies in the field and discuss the prognostic and treatment implications of recent insights in 'lone' AF pathophysiology.