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

A prospective randomized controlled trial on the incidence and predictors of late-phase postoperative atrial fibrillation up to 30 days and the preventive value of biatrial pacing

BACKGROUND

Postoperative atrial fibrillation (POAF) is considered to be a transient arrhythmia in the first week after cardiac surgery.

OBJECTIVE

To determine the 30-day incidence and predictors of POAF and the value of postoperative overdrive biatrial pacing in the prevention of POAF.

METHODS

Patients (n = 148) without a history of atrial fibrillation undergoing aortic valve replacement or coronary artery bypass graft (CABG) were randomized into a pacing group (n = 75) and a control group. Patients were treated with standardized sotalol postoperatively. Rhythm was continuously monitored for 30 days by a transtelephonic event recorder.

RESULTS

POAF occurred in 73 (49.3%) patients, of whom 60 (40.5%) patients showed POAF during postoperative days (PODs) 0-5 and 37 (25%) patients during PODs 6-30. Prolonged aortic cross-clamp time was an important univariate predictor of 30-day and of late POAF (PODs 6-30; P = .017 and P = .03, respectively). Best-fit model analysis using 15 predetermined risk factors for POAF showed different positive interactive effects for early POAF (ie, baseline C-reactive protein levels with a history of myocardial infarction or low body mass index) and late POAF (ie, high body mass index, diabetes mellitus, baseline C-reactive protein, early POAF, creatinine levels, type of operation, smoking, and male gender). Biatrial pacing reduced the late POAF incidence in patients with aortic cross-clamp time >50 minutes (P = .006).

CONCLUSION

POAF is not limited to the first week after cardiac surgery but also occurs frequently in the postoperative month. It is desirable to regularly follow patients with POAF for atrial fibrillation recurrences after discharge.

Deteriorating renal function and clinical outcomes in HIV-positive persons

OBJECTIVES

To determine the relationship between measures of renal function [current estimated glomerular filtration rate (eGFR) and proportion of follow-up with a low eGFR (%FU ≤60 ml/min)] and fatal/ nonfatal AIDS, non-AIDS events and all-cause mortality.

DESIGN

An observational, longitudinal cohort study of 12 155 persons from EuroSIDA.

METHODS

Persons with at least one eGFR measurement after 1 January 2004, using the CKD-EPI formula, were included. Poisson regression analyses were used to determine whether current eGFR or %FU of 60 ml/min or less were independent prognostic markers for clinical events.

RESULTS

During 61 425 person-years of follow-up (PYFU), the crude incidence of deaths was 11.1/1000 PYFU [95% confidence interval (CI) 10.0-12.1] at current eGFR more than 90 ml/min and 199.6 (95% CI 1144.3-254.3/1000 PYFU) when current eGFR was 30 ml/min or less. Corresponding figures for AIDS were 12.2 (11.1-13.3) and 63.9 (36.5-103.7) and for non-AIDS were 16.0 (14.8-17.3) and 203.6 (147.7-259.5). After adjustment, current eGFR of 30 ml/min or less was a strong predictor of death [adjusted incidence rate ratios (aIRR) 4.35; 95% CI 3.20-5.91] and non-AIDS events (3.63; 95% CI 2.57-5.13), although the relationship with AIDS was less strong (1.45; 95% CI 1.01-2.08). After adjustment, %FU of 60 ml/min or less was associated with a 22% increased incidence of death (aIRR 1.22 per 10% longer; 95% CI 1.18-1.27), a 13% increased incidence of non-AIDS events (95% CI 1.08-1.18) and a 15% increased incidence of AIDS events (95% CI 1.06-1.24).

CONCLUSION

Both current eGFR and %FU of 60 ml/min or less were associated with death and non-AIDS events in HIV-positive persons. Our findings highlight the association between underlying renal dysfunction and morbidity and mortality in HIV infection, although reverse causality cannot be excluded.

Different types of atrial fibrillation, renal function, and mortality in elderly Chinese patients with coronary artery disease

Background

Atrial fibrillation (AF) is the most common arrhythmia in patients with chronic kidney disease (CKD), and the combined prevalence of these two disorders increases as the population ages. Both AF and CKD have risk factors for development of each other and eventual mortality. However, the relationship between different types of AF, CKD, and mortality remains unclear, especially in elderly Chinese patients with coronary artery disease.

Methods

This study comprised 1,050 patients of median age 86 (60–104) years with coronary artery disease. The end point was all-cause death during a mean follow-up of 417 days.

Results

Of 219 patients identified to have AF, 128 had paroxysmal type, 44 had persistent type, and 47 had permanent type. After adjusting for confounders, the estimated glomerular filtration rate was lower and the prevalence of CKD was higher in patients with permanent AF but not in those with paroxysmal or persistent AF. During follow-up, 106 non-CKD patients and 112 CKD patients died; mortality was significantly higher in CKD patients with AF than in those without AF (36 [40.9%] versus 76 [26.8%]), but not in patients without CKD (17 [13.0%] versus 89 [16.3%]). In patients with CKD, paroxysmal AF was independently associated with higher mortality after adjustment but not persistent or permanent AF. No type of AF had an independent association with mortality in patients without CKD.

Conclusion

All types of AF had a high prevalence. Permanent AF was independently associated with an increased prevalence of CKD and a decreased estimated glomerular filtration rate. Paroxysmal AF was an independent risk factor for survival in patients with CKD but not in those without CKD.

Efficacy and safety of dabigatran compared with warfarin in relation to baseline renal function in patients with atrial fibrillation: a RE-LY (Randomized Evaluation of Long-term Anticoagulation Therapy) trial analysis

BACKGROUND

Renal impairment increases the risk of stroke and bleeding in patients with atrial fibrillation. In the Randomized Evaluation of Long-Term Anticoagulant Therapy (RELY) trial, dabigatran, with ≈80% renal elimination, displayed superiority over warfarin for prevention of stroke and systemic embolism in the 150-mg dose and significantly less major bleeding in the 110-mg dose in 18 113 patients with nonvalvular atrial fibrillation. This prespecified study investigated these outcomes in relation to renal function.

METHODS AND RESULTS

Glomerular filtration rate was estimated with the Cockcroft-Gault, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), and Modification of Diet in Renal Disease (MDRD) equations in all randomized patients with available creatinine at baseline (n=17 951), and cystatin C-based glomerular filtration rate was estimated in a subpopulation with measurements available (n=6190). A glomerular filtration rate ≥80, 50 to <80, and <50 mL/min was estimated in 32.6%, 47.6%, and 19.8% and in 21.6%, 59.6%, and 18.8% of patients based on Cockcroft-Gault and CKD-EPI, respectively. Rates of stroke or systemic embolism, major bleeding, and all-cause mortality increased as renal function decreased. The rates of stroke or systemic embolism were lower with dabigatran 150 mg and similar with 110 mg twice daily compared with warfarin, without significant heterogeneity in subgroups defined by renal function (interaction P>0.1 for all). For the outcome of major bleeding, there were significant interactions between treatment and renal function according to CKD-EPI and MDRD equations, respectively (P<0.05). The relative reduction in major bleeding with either dabigatran dose compared with warfarin was greater in patients with glomerular filtration rate ≥80 mL/min.

CONCLUSIONS

The efficacy of both dosages of dabigatran was consistent with the overall trial irrespective of renal function. However, with the CKD-EPI and MDRD equations, both dabigatran dosages displayed significantly lower rates of major bleeding in patients with glomerular filtration rate ≥80 mL/min.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00262600.

Epicardial adipose tissue is associated with prevalent atrial fibrillation in patients with hypertrophic cardiomyopathy

Prevalent atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM) represents an important issue with regard to stroke events caused by embolization and is associated with high mortality. Increased epicardial adipose tissue (EAT), which shows high metabolic activity, can locally influence the activity of the autonomic ganglia, enhancing autonomic dysregulation and increasing the likelihood of AF. We tested the hypothesis that EAT is associated with prevalent AF in HCM patients. Sixty-two patients with idiopathic HCM diagnosed on the basis of ultrasound cardiography findings and histopathological evaluation of myocardium obtained by right ventricular biopsy underwent cardiac magnetic resonance imaging to estimate the extent of EAT. EAT area was significantly higher in the group with AF episodes than in the group without. An increased incidence of AF was found to be significantly related to an increase in EAT, and this association persisted after adjustment for body mass index, sex, and age. Time domain measures of heart rate variability measured by Holter electrocardiography, standard deviation of normal to normal, and standard deviation of the average of normal to normal were negatively related to EAT area. EAT was positively correlated with intraventricular septal thickness and cystatin C level and negatively correlated with the 24-hour creatinine clearance rate. Increased EAT area in HCM patients is significantly related to the presence of AF, which is associated with changes in baseline autonomic nervous tone, left ventricular mass, and chronic kidney disease.

Estimated glomerular filtration rate and proteinuria are separately and independently associated with the prevalence of atrial fibrillation in general population

BACKGROUND

Both, proteinuria and a decline in glomerular filtration rate (GFR) are associated with greater cardiovascular mortality. However, few studies have explored that proteinuria and lower GFR are related with prevalent atrial fibrillation (AF).

METHODS

This cross-sectional study was based on annual health check-up program of community-based population in Gunma, Japan from April 2011 to March 2012. A total of 20,019 adult participants were included. AF was ascertained by a standard 12-lead electrocardiogram. Cross-sectional association and correlates with prevalent AF were examined using multivariable logistic regression analysis.

RESULTS

The overall prevalence of AF was 0.6% (2.2 % in participants with eGFR < 60 mL▪min(-1)･1.73m(-2), 0.4% and 0.2% in those with eGFR 60 to 89 and ≧90 mL▪min(-1)･1.73m(-2), p for trend <0.001). The multivariable odds ratio (OR) for AF was 2.86 (95 % CI 1.16 - 7.08, p<0.001) for eGFR< 60 mL▪min(-1)▪1.73m(-2) versus eGFR≧ 90 mL▪min(-1)▪1.73m(-2). This association remained significant with further adjustment for proteinuria. In addition, proteinuria was also strongly associated with increased prevalence of AF (OR 2.96, 95 % CI 1.55-5.68, p<0.001), an association that remained significant after adjustment for eGFR.

CONCLUSIONS

Proteinuria and lower eGFR are separately and significantly associated with prevalence of AF independent of well-established risk factors for AF in general population.

Recent developments in understanding epidemiology and risk determinants of atrial fibrillation as a cause of stroke

The prevalence of atrial fibrillation (AF) is increasing because of the aging population and advances in the treatment of acute cardiac conditions. It is now approaching epidemic proportions and is associated with significant clinical and public health consequences. Risk factors for the development of AF are numerous and varied and highlight potential treatment measures that could help prevent the occurrence of AF. The emergence of novel risk factors might allow us to increase our understanding of the pathophysiology of the condition and develop novel therapeutic targets. Stroke is the most devastating consequence of AF, and can be prevented with effective oral anticoagulation in patients at increased stroke risk. Our understanding of stroke risk has advanced; we know that the risk is not homogenous and also that only the very lowest risk patients do not benefit from anticoagulation. Clinicians should target their efforts on identifying this "truly low-risk" patient cohort and consider offering formal anticoagulation to all other AF patients. The purpose of this review is to consider the traditional and emerging risk factors for the development of AF itself, and the risk factors for stroke in AF patients and how knowledge of these risk factors can affect clinical practice.

Renal function and outcomes in anticoagulated patients with non-valvular atrial fibrillation: the AMADEUS trial

AIMS

Limited data are available on the impact of renal function on the outcome of patients with atrial fibrillation (AF).

METHODS AND RESULTS

AMADEUS was a multicentre, randomized, open-label non-inferiority study that compared fixed-dose idraparinux with conventional anticoagulation by dose-adjusted vitamin K antagonists. We performed a post hoc analysis to assess the impact of renal function on the outcomes of anticoagulated AF patients. The primary efficacy outcome was the composite of stroke/systemic embolism (SE). The principal safety outcome of this analysis was major bleeding. We calculated c-indexes, reflecting the ability for discriminating diseased vs. non-diseased patients, and the net reclassification improvement (NRI, an index of inferior/superior performance of risk estimation scores). Of 4576 patients, 45 strokes and 103 major bleeding events occurred following an average follow-up of 325 ± 164 days. Patients with CrCl >90 mL/min had an annual stroke/SE rate of 0.6% compared with 0.8% for those with CrCl 60-90 mL/min and 2.2% for those with CrCl <60 mL/min (P < 0.001 for linear association). After adjusting for stroke risk factors, patients with CrCl <60 mL/min had more than two-fold higher risk of stroke/SE and almost 60% higher risk of major bleeding compared with those with CrCl ≥60. In patients with the CHA2DS2VASc score 1-2, CrCl <60 mL/min was associated with eight-fold higher stroke risk. When added to the CHA2DS2VASc or CHADS2 scores, CrCl <60 mL/min did not improve the c-indexes for CHADS2 (P = 0.054) or CHA2DS2VASc (P = 0.63) but resulted in significant NRI (0.26, P = 0.02) in this anticoagulated trial cohort.

CONCLUSION

Renal impairment (CrCl <60 mL/min) doubles the risk of stroke and increased the risk of major bleeding by almost 60% in anticoagulated patients with AF. Renal impairment was additive to stroke risk prediction scores based on a significant NRI, but no significant improvement in discrimination ability (based on c-indexes) for CHA2DS2VASc or CHADS2 was observed.

Atrial fibrillation: profile and burden of an evolving epidemic in the 21st century

BACKGROUND

Atrial fibrillation (AF) represents an increasing public health challenge with profound social and economic implications.

METHODS

A comprehensive synthesis and review of the AF literature was performed. Overall, key findings from 182 studies were used to describe the indicative scope and impact of AF from an individual to population perspective.

RESULTS

There are many pathways to AF including advancing age, cardiovascular disease and increased levels of obesity/metabolic disorders. The reported population prevalence of AF ranges from 2.3%-3.4% and historical trends reflect increased AF incidence. Estimated life-time risk of AF is around 1 in 4. Primary care contacts reflect whole population trends: AF-related case-presentations increase from less than 0.5% in those aged 40 years or less to 6-12% for those aged 85 years or more. Globally, AF-related hospitalisations (primary or secondary diagnosis) showed an upward trend (from ~35 to over 100 admissions/10,000 persons) during 1996 to 2006. The estimated cost of AF is greater than 1% of health care expenditure and rising with hospitalisations the largest contributor. For affected individuals, quality of life indices are poor and AF confers an independent 1.5 to 2.0-fold probability of death in the longer-term. AF is also closely linked to ischaemic stroke (3- to 5-fold risk), chronic heart failure (up to 50% develop AF) and acute coronary syndromes (up to 25% develop AF) with consistently worse outcomes reported with concurrent AF. Future projections predict at least a doubling of AF cases by 2050.

SUMMARY

AF represents an evolving, global epidemic providing considerable challenges to minimise its impact from an individual to whole society perspective.

Incident atrial fibrillation and risk of end-stage renal disease 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 adverse renal outcomes in patients with CKD is unknown. In this study, we determined the association between incident AF and risk of end-stage renal disease (ESRD) among adults with CKD.

METHODS AND RESULTS

We studied adults with CKD (defined as estimated glomerular filtration rate eGFR <60 mL/min per 1.73 m(2) by the Chronic Kidney Disease Epidemiology Collaboration equation) enrolled in Kaiser Permanente Northern California who were identified between 2002 and 2010 and who did not have previous ESRD or previously documented AF. Incident AF was identified by using primary hospital discharge diagnoses or 2 or more outpatient visits for AF. Incident ESRD was ascertained from a comprehensive health plan registry for dialysis and renal transplant. Among 206 229 adults with CKD, 16 463 developed incident AF. During a mean follow-up of 5.1±2.5 years, there were 345 cases of ESRD that occurred after development of incident AF (74 per 1000 person-years) in comparison with 6505 cases of ESRD during periods without AF (64 per 1000 person-years, P<0.001). After adjustment for potential confounders, incident AF was associated with a 67% increase in the rate of ESRD (hazard ratio, 1.67; 95% confidence interval, 1.46-1.91).

CONCLUSIONS

Incident AF is independently associated with increased risk of developing ESRD in adults with CKD. Further study is needed to identify potentially modifiable pathways through which AF leads to a higher risk of progression to ESRD.

Renal dysfunction as a predictor of stroke and systemic embolism in patients with nonvalvular atrial fibrillation: validation of the R(2)CHADS(2) index in the ROCKET AF (Rivaroxaban Once-daily, oral, direct factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in Atrial Fibrillation) and ATRIA (AnTicoagulation and Risk factors In Atrial fibrillation) study cohorts

BACKGROUND

We sought to define the factors associated with the occurrence of stroke and systemic embolism in a large, international atrial fibrillation (AF) trial.

METHODS AND RESULTS

In ROCKET AF (Rivaroxaban Once-daily, oral, direct factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in Atrial Fibrillation), 14 264 patients with nonvalvular AF and creatinine clearance ≥30 mL/min were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards modeling was used to identify factors at randomization independently associated with the occurrence of stroke or non-central nervous system embolism based on intention-to-treat analysis. A risk score was developed in ROCKET AF and validated in ATRIA (AnTicoagulation and Risk factors In Atrial fibrillation), an independent AF patient cohort. Over a median follow-up of 1.94 years, 575 patients (4.0%) experienced primary end-point events. Reduced creatinine clearance was a strong, independent predictor of stroke and systemic embolism, second only to prior stroke or transient ischemic attack. Additional factors associated with stroke and systemic embolism included elevated diastolic blood pressure and heart rate, as well as vascular disease of the heart and limbs (C-index 0.635). A model that included creatinine clearance (R(2)CHADS(2)) improved net reclassification index by 6.2% compared with CHA(2)DS(2)VASc (C statistic=0.578) and by 8.2% compared with CHADS(2) (C statistic=0.575). The inclusion of creatinine clearance <60 mL/min and prior stroke or transient ischemic attack in a model with no other covariates led to a C statistic of 0.590.Validation of R(2)CHADS(2) in an external, separate population improved net reclassification index by 17.4% (95% confidence interval, 12.1%-22.5%) relative to CHADS(2).

CONCLUSIONS

In patients with nonvalvular AF at moderate to high risk of stroke, impaired renal function is a potent predictor of stroke and systemic embolism. Stroke risk stratification in patients with AF should include renal function.

CLINICAL TRIAL REGISTRATION

URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00403767.

Race-specific impact of atrial fibrillation risk factors in blacks and whites in the southern community cohort study

Despite a greater burden of traditional risk factors, atrial fibrillation (AF) is less common among blacks than whites for reasons that are unclear. The aim of this study was to examine race- and gender-specific influences of demographic, lifestyle, anthropometric, and medical factors on AF in a large cohort of blacks and whites. Among white and black participants in the Southern Community Cohort Study (SCCS) aged ≥65 years receiving Medicare coverage from 1999 to 2008 (n = 8,836), diagnoses of AF (International Classification of Diseases, Ninth Revision, Clinical Modification code 427.3) were ascertained. Multivariate logistic regression was used to compute AF odds ratios associated with participant characteristics, including histories of hypertension, diabetes, stroke, and myocardial infarction or coronary artery bypass graft surgery, ascertained at cohort entry. Over an average of 5.7 years of Medicare coverage, AF was diagnosed in 1,062 participants. AF prevalence was significantly lower among blacks (11%) than whites (15%) (p <0.0001). Odds ratios for AF increased with age and were higher among men, the tall and obese, and patients with each of the co-morbid conditions, but the AF deficit among blacks compared to whites persisted after adjustment for these factors (odds ratio 0.64, 95% confidence interval 0.55 to 0.73). The patterns of AF risk were similar for blacks and whites, although associations with hypertension, diabetes, and stroke were somewhat stronger among blacks. In conclusion, these findings confirm the lower prevalence of AF among blacks than whites and suggest that traditional risk factors for AF apply similarly to the 2 groups and thus do not appear to explain the AF paradox in blacks.

Anticoagulation for atrial fibrillation in patients on dialysis: are the benefits worth the risks?

PURPOSE OF REVIEW

Atrial fibrillation is common among patients with end-stage renal disease undergoing hemodialysis. Although oral anticoagulation is recommended for stroke prevention in most patients with atrial fibrillation, limited evidence is available to guide treatment in hemodialysis patients with this arrhythmia. We summarize the available evidence on the epidemiology of atrial fibrillation in dialysis patients and review the data on the effectiveness of oral anticoagulation in this population.

RECENT FINDINGS

Atrial fibrillation is increasingly common in patients undergoing chronic hemodialysis, especially among older patients wherein one in six patients is diagnosed with this arrhythmia. Patients with atrial fibrillation experience double the mortality of otherwise similar patients without it. Few hemodialysis patients with atrial fibrillation receive oral anticoagulation, which is consistently associated with excess risks of hemorrhagic stroke. Observational studies did not detect a beneficial association of oral anticoagulation with the risk of ischemic stroke, with some studies describing higher risks of ischemic stroke among warfarin users. New therapeutic options including one oral direct thrombin inhibitor and two oral factor Xa inhibitors have become available, but were not tested in patients with advanced kidney disease.

SUMMARY

Atrial fibrillation is increasingly common in patients undergoing hemodialysis, yet little is known about the optimal management of these patients. The current evidence does not support net benefits from oral anticoagulation in the dialysis population.

Trends in the incidence of atrial fibrillation in older patients initiating dialysis in the United States

BACKGROUND

One sixth of US dialysis patients 65 years of age have been diagnosed with atrial fibrillation/flutter (AF). Little is known, however, about the incidence of AF in this population.

METHODS AND RESULTS

We identified 258 605 older patients (≥67 years of age) with fee-for-service Medicare initiating dialysis in 1995 to 2007, who had not been diagnosed with AF within the previous 2 years. Patients were followed for newly diagnosed AF. Multivariable proportional hazard regression was used to examine temporal trends and associations of race and ethnicity with incident AF. We also studied temporal trends in the mortality and risk of ischemic stroke after new AF. Over 514 395 person-years of follow-up, 76 252 patients experienced incident AF for a crude AF incidence rate of 148/1000 person-years. Incidence of AF increased by 11% (95% confidence interval, 5-16) from 1995 to 2007. Compared with non-Hispanic whites, blacks (-30%), Asians (-19%), Native Americans (-42%), and Hispanics (-29%) all had lower rates of incident AF. Mortality after incident AF decreased by 22% from 1995 to 2008. Even more pronounced reductions were seen for incident ischemic stroke during these years.

CONCLUSIONS

The incidence of AF is high in older patients initiating dialysis in the United States and has been increasing over the 13 years of study. Mortality declined during that time but remained >50% during the first year after newly diagnosed AF. Because data on warfarin use were not available, we were unable to study whether trends toward better outcomes could be explained by higher rates of oral anticoagulation.

A proposal for new clinical concepts in the management of atrial fibrillation

Atrial fibrillation (AF) represents a growing public health burden. It is a complex condition, involving a number of etiologic factors and arrhythmia mechanisms associated with atrial remodeling. Greater understanding of these mechanisms may improve therapy. Current AF classification schemes are limited by simplicity. A number of risk factors predict AF onset, and additional factors are being evaluated in registry studies. Doppler imaging and Holter monitoring in high-risk patients to predict the onset of AF and progression from paroxysmal to permanent AF are promising. There is a need for a novel multifactorial classification model encompassing AF duration, symptoms, markers of atrial remodeling, and a risk score for AF onset, persistence, progression, and complications to guide treatment and prognostication. Preventing AF onset with upstream therapy is of great interest, but current data are conflicting. More study is needed to optimize rhythm control with antiarrhythmic drugs and targeted ablation to specific patient populations at an earlier stage. There is little consensus on optimal rate control and no information relating to optimum rate control in specific populations. This article highlights new concepts in AF and directions for future research.

Impact of chronic kidney disease on risk of incident atrial fibrillation and subsequent survival in medicare patients

Background

Atrial fibrillation (AF) and chronic kidney disease (CKD) are prevalent in the elderly and are independently associated with increased risk of death. We evaluated risk of incident AF with advancing CKD and examined the mortality rate associated with CKD after incident AF in elderly patients.

Methods and Results

This retrospective cohort study used the Medicare 5% database. Point-prevalent Medicare enrollees on December 31, 2006, without preexistent AF or end-stage renal disease were followed up for incident AF through 2008. CKD and AF were identified from International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. Associations between CKD stage and incident AF and subsequent risk of death were examined in a Cox proportional-hazards model. Unadjusted survival after incident AF was estimated by the Kaplan-Meier method. CKD was present in 55 962 patients (5.1% of the cohort). Of these, 4952 (8.8%) had CKD stages 1 and 2; 19 795 (35.3%), stages 3 to 5; and 31 215 (55.7%), unknown stage. The hazard ratio for incident AF in CKD stages 3 to 5 was 1.13 (95% confidence interval 1.09 to 1.18). Other stages were not independently associated with incident AF. Survival after incident AF decreased progressively as CKD stage increased (P<0.0001). The 1-year mortality rate for CKD stages 3 to 5 with incident AF was 35.6%. Adjusted hazard ratios for death after incident AF were 1.14 (95% confidence interval 1.00 to 1.30) for CKD stages 1 and 2, 1.27 (95% confidence interval 1.20 to 1.35) for CKD stages 3 to 5, and 1.29 (95% confidence interval 1.23 to 1.36) for unknown stage.

Conclusions

Advanced CKD is associated with increased risk of incident AF. In Medicare patients with incident AF, mortality rates are higher for those with advanced CKD than for those without CKD. (J Am Heart Assoc. 2012;1:e002097 doi: 10.1161/JAHA.112.002097.)

Establishment of a model of atrial fibrillation associated with chronic kidney disease in rats and the role of oxidative stress

BACKGROUND

An animal model of atrial fibrillation (AF) associated with chronic kidney disease (CKD) has not been available.

OBJECTIVE

The purpose of this study was to test the validity of 5/6 nephrectomy (5.6Nx) as an appropriate model of AF associated with CKD and to investigate the role of oxidative stress.

METHODS

Male Sprague-Dawley rats were subjected to 5.6Nx. A novel derivative of lipoic acid, sodium zinc dihydrolipoylhistidinate (DHLHZn), was subcutaneously infused. Four weeks later, hearts were isolated.

RESULTS

We observed 5 main findings. (1) 5.6Nx induced renal dysfunction with elevation of systolic blood pressure and impaired glucose tolerance. (2) In the left atrium (LA), expressions of α-smooth muscle action and collagen type I, the compositional proteins of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, and malondialdehyde were increased by 5.6Nx, which was reversed by DHLHZn treatment. (3) In the LA, the tissue content of angiotensin II was elevated by 5.6Nx, which was also reversed by DHLHZn. (4) Masson trichrome staining revealed that heterogeneous LA interstitial fibrosis was induced by 5.6Nx, which was attenuated by DHLHZn. (5) In isolated perfused heart experiments, 5.6Nx caused slowing of interatrial conduction. In the hearts of rats of the 5.6Nxgroup, right atrial extrastimuli invariably induced AF (8/8 [100%]), which were suppressed by DHLHZn (3/8 [38%], P <.05).

CONCLUSION

We successfully established an appropriate model of AF associated with CKD in rats. Because the amount of NADPH oxidase was increased and the potent antioxidant agent DHLHZn was effective, oxidative stress may be involved in the pathogenesis of LA fibrosis and enhanced AF vulnerability in our model.

Chronic Kidney Disease and Atrial Fibrillation: A Contemporary Overview

Chronic kidney disease (CKD) is associated with substantial cardiovascular morbidity, including myocardial infarction, heart failure and stroke. Similar to CKD, atrial fibrillation (AF) is a prevalent arrhythmia that increases risk for both stroke and overall mortality. Recent studies demonstrate that both prevalence and incidence of AF is higher in patient with versus without renal impairment and risk for developing AF increases as renal function worsens. Potential mechanisms for the higher burden of AF in CKD patients include but are not limited to augmented sympathetic tone, activation of the renin-angiotensin-aldosterone system and myocardial remodeling. Similar to the general population, AF confers an increased risk for both stroke and overall mortality in the CKD population. The safety and efficacy of antithrombotic therapy across the spectrum of CKD remains unknown, however, as patients with advanced renal failure are frequently excluded from randomized trials. While treatment with vitamin K antagonists appears to reduce ischemic complications without significant bleeding harm in patients with mild to moderate CKD and AF, the risk benefit ratio of anticoagulation among thosewith advanced renal failure on dialysis requires further investigation. Prospective, randomized trials are war ranted to define the impact of antithrombotic therapy on reducing stroke risk in patients with both AF and CKD.

The Relationship Between Atrial Fibrillation and Chronic Kidney Disease : Epidemiologic and Pathophysiologic Considerations for a Dual Epidemic

Atrial fibrillation (AF) presently affects over 2 million Americans, and the magnitude and population burden from AF continues to increase concomitant with the aging of the U.S.

POPULATION

Chronic kidney disease (CKD) is present in 13% of individuals in the U.S., and the prevalence of CKD is also rapidly increasing. The increasing population burden of CKD and AF will profoundly affect the clinical and public health, since CKD and AF are both associated with lower quality of life, increased hospitalization rates, and a greater risk of heart failure, stroke, and total mortality. AF and CKD often co-exist, each condition predisposes to the other, and the co-occurrence of these disorders worsens prognosis relative to either disease alone. The shared epidemiology of CKD and AF may be explained by the strong pathophysiologic connections between these diseases. In order to promote a better understanding of CKD and AF, we have reviewed their shared epidemiology and pathophysiology and described the natural history of patients affected by both diseases.

Cardio-renal syndrome type 4: epidemiology, pathophysiology and treatment

Cardiovascular diseases such as coronary artery disease, congestive heart failure, arrhythmia, and sudden cardiac death represent the leading causes of morbidity and mortality in patients with CKD, increasing sharply as patients approach end-stage renal disease. The pathogenesis includes a complex, bidirectional interaction between the heart and kidneys that encompasses traditional and nontraditional risk factors, and has been termed cardio-renal syndrome type 4. In this review, an overview of the epidemiology and scope of this problem is provided, some suggested mechanisms for the pathophysiology of this disorder are discussed, and some of the key treatment strategies are described, with particular focus on recent clinical trials, both negative and positive.

Atrial Fibrillation and Oral Anticoagulation in Chronic Kidney Disease

Due to several unfavorable epidemiological changes, chronic kidney disease (CKD) and treatment of its associated cardiovascular morbidity have become a worldwide problem. Thus, atrial fibrillation (AF) is the most common arrhythmia and frequently associated with renal impairment: prevalence for AF is up to 27% in long-term hemodialysis patients and in general more than 25% in all CKD patients 70 years and older. Thromboembolism and stroke are the major complications of AF. Two-year death rates for CKD patients after stroke range between 55% and 74%. Although treatment of AF in the general population is well defined, patients with CKD and AF are often undertreated due to lack of studies and guidelines. In this review recent data concerning incidence and prevalence of AF, stroke, and major bleedings in CKD patients are presented. Particular attention is paid to the available data about the different types of oral anticoagulation therapy with regard to CKD stage, including the new oral anticoagulant drugs dabigatran, rivaroxaban, and apixaban. Stratification algorithms for stroke risk in general, and individualized risk stratification for oral anticoagulation in CKD patients are discussed in detail.

Impact of Chronic Anemia on the New-Onset Atrial Fibrillation in the Elderly: It May Not Be What We Have Thought

Objective: To determine if a clinically significant relation exists between chronic anemia and the new-onset atrial fibrillation (AF) in the elderly population from a community setting. Patients and Methods: This is a single center community-based retrospective cohort study. Data were collected on 3867 patients over the age of 65 years presenting to the Mercy Medical Center in the year 2006. Patients without AF were divided into anemic and non-anemic groups and were followed over the next two years for the new-onset AF. Chronic anemia was defined as hemoglobin level less than 13g/dl in males and less than 12g/dl in females from two laboratory values checked at least 4 months apart. Results: Of the 2873 patients without AF, 2382 (83%) patients were non-anemic. 491 patients were anemic. New-onset AF was found in 7.5 % of the anemic patients and 5.5% of the non-anemic patients. After the adjustment for comorbid conditions, chronic anemia is not associated with new-onset AF (p=0.922). Conclusion: In this study cohort of elderly community-based patients, chronic anemia is not associated with the new-onset AF.

Electrocardiogram abnormalities and cardiovascular mortality in elderly patients with CKD

BACKGROUND AND OBJECTIVES

Cardiovascular disease is the most common cause of death in CKD. This study evaluated whether electrocardiogram (ECG) abnormalities are predictors of cardiovascular death in CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Cardiovascular Health Study limited database (1989-2005) was used to identify a cohort with CKD at baseline (estimated GFR < 60 mL/min per 1.73 m(2)). The patients were categorized as having major, minor, or no ECG abnormalities. Rates of adjudicated cardiovascular events and mortality were compared among the groups using proportional hazards regression models.

RESULTS

A total of 1192 participants had CKD at baseline; mean age ± SD was 74.7±6.2 years. Of these patients, 452 (38.8%) had major, 346 (29.7%) had minor, and 367 (31.5%) had no ECG abnormalities. Participants with estimated GFR < 60 mL/min per 1.73 m(2) were more likely to have ECG abnormalities at baseline (adjusted prevalence odds ratio, 1.23 [95% confidence interval (CI), 1.06-1.43]) than those with GFR ≥ 60 mL/min per 1.73 m(2). During mean follow-up of 10.3±3.8 years, 814 (68.3%) participants died. Compared with participants without ECG abnormalities, participants with major abnormalities had the highest risk for cardiovascular events and death; adjusted hazard ratios were 2.15 (95% CI, 1.56-2.98) and 2.27 (95% CI, 1.56-3.30), respectively. For minor ECG abnormalities, hazard ratios were 1.24 (95% CI, 0.91-1.70) and 1.48 (95% CI, 1.00-2.18), respectively.

CONCLUSIONS

In patients with CKD, major ECG abnormalities are frequently present and predict a significantly higher risk for death and adverse cardiovascular outcomes.

Lone atrial fibrillation: where are we now?

There is a growing pandemic of atrial fibrillation (AF), affecting nearly 2% of the general adult population. Atrial fibrillation is commonly associated with structural heart disease, and AF itself causes a sequence of complex processes of electrical, contractile, and structural remodeling of the atrial myocardium, which facilitate further AF progression. Nonetheless, AF may also affect individuals aged ≤ 65 years who have no evidence of associated cardiopulmonary or other disease, including hypertension; this is otherwise referred to as "lone" AF and is considered to have a generally favorable prognosis. The true prevalence of lone AF is unknown. Growing insights into the diversity of numerous mechanisms involved in the pathogenesis of AF, including acute atrial stretch, structural and electrophysiological alterations, systemic inflammation, oxidative stress, autonomic imbalance, genetic predisposition, and many others, and increasing recognition of novel risk factors for AF, including obesity, metabolic syndrome, subclinical atherosclerosis, sleep apnea, alcohol consumption, and endurance sports, suggest that apparently lone AF might not be so "lone" in many patients, which could have important prognostic and therapeutic implications. In this article, we summarize the current knowledge of epidemiology, etiopathogenesis, and pathophysiology of so-called lone AF and discuss the issues of long-term prognosis and management of patients who have an apparently lone AF.

Comprehensive risk reduction in patients with atrial fibrillation: emerging diagnostic and therapeutic options--a report from the 3rd Atrial Fibrillation Competence NETwork/European Heart Rhythm Association consensus conference

While management of atrial fibrillation (AF) patients is improved by guideline-conform application of anticoagulant therapy, rate control, rhythm control, and therapy of accompanying heart disease, the morbidity and mortality associated with AF remain unacceptably high. This paper describes the proceedings of the 3rd Atrial Fibrillation NETwork (AFNET)/European Heart Rhythm Association (EHRA) consensus conference that convened over 60 scientists and representatives from industry to jointly discuss emerging therapeutic and diagnostic improvements to achieve better management of AF patients. The paper covers four chapters: (i) risk factors and risk markers for AF; (ii) pathophysiological classification of AF; (iii) relevance of monitored AF duration for AF-related outcomes; and (iv) perspectives and needs for implementing better antithrombotic therapy. Relevant published literature for each section is covered, and suggestions for the improvement of management in each area are put forward. Combined, the propositions formulate a perspective to implement comprehensive management in AF.

The predictive value of cardiac biomarkers in prognosis and risk stratification of patients with atrial fibrillation

PURPOSE OF REVIEW

Atrial fibrillation is a significant public health issue considering its high prevalence in the general population, and is associated with an increased risk of cardiovascular mortality and morbidity and thrombo-embolic complications.Asymptomatic paroxysms of atrial fibrillation occur frequently in the first stages of the disease but patients present to the doctor at a relatively late stage when the associated complications have already taken place. It is crucial to identify such patients as early as possible in order to start preventive therapy. Clinical diagnostic tests to identify patients prone to atrial fibrillation complications have not yet been developed as the exact mechanism and substrate of subclinical atrial fibrillation are not known. Further research is necessary to understand the pathophysiology of subclinical atrial fibrillation and to identify potential risk markers that determine the development and prognosis of the disease.

RECENT FINDINGS

Biomarkers have recently been identified which have been shown to be related to the incidence of atrial fibrillation and its prognosis. They reflect inflammation, neurohumoral activation and subclinical heart damage.

SUMMARY

New biomarkers may help to understand the mechanisms of subclinical atrial fibrillation and signal the likelihood of disease progression. Such biomarkers, though subject to further validation, may be of value in predicting the prognosis and guiding the treatment of patients with atrial fibrillation. They may enhance the ability of risk scores to guide anticoagulant treatment strategies.

Differential impact of race and risk factors on incidence of atrial fibrillation

Despite some common risk factors for atrial fibrillation (AF) being more prevalent among blacks, African Americans are increasingly being reported with lower prevalence and incidence of AF compared with whites. Contemporary studies have not provided a complete explanation for this apparent AF paradox in African Americans. Although many traditional and novel risk factors for AF have been identified, the role of ethnic-specific risk factors has not been examined. Whereas hypertension has been the most common risk factor associated with AF, coronary artery disease also plays an important role in AF pathophysiology in whites. Thereby, elucidating the role of ethnic-specific risk factors for AF may provide important insight into why African Americans are protected from AF or why whites are more prone to develop the arrhythmia. The link between AF susceptibility and genetic processes has only been recently uncovered. Polymorphisms in renin-angiotensin system genes have been characterized as predisposing to AF under certain environmental conditions. Several ion channel genes, signaling molecules, and several genetic loci have been linked with AF. Thereby, studies investigating genetic variants contributing to the differential AF risk in individuals of African American versus European ancestry may also provide important insight into the etiology of the AF paradox in blacks.