Racial variation in the prevalence of atrial fibrillation among patients with heart failure

Assessing ascertainment bias in atrial fibrillation across US minority groups

The aim of this study is to define atrial fibrillation (AF) prevalence and incidence rates across minority groups in the United States (US), to aid in diversity enrollment target setting for randomized controlled trials. In AF, US minority groups have lower clinically detected prevalence compared to the non-Hispanic or Latino White (NHW) population. We assess the impact of ascertainment bias on AF prevalence estimates. We analyzed data from adults in Optum's de-identified Clinformatics® Data Mart Database from 2017-2020 in a cohort study. Presence of AF at baseline was identified from inpatient and/or outpatient encounters claims using validated ICD-10-CM diagnosis algorithms. AF incidence and prevalence rates were determined both in the overall population, as well as in a population with a recent stroke event, where monitoring for AF is assumed. Differences in prevalence across cohorts were assessed to determine if ascertainment bias contributes to the variation in AF prevalence across US minority groups. The period prevalence was respectively 4.9%, 3.2%, 2.1% and 5.9% in the Black or African American, Asian, Hispanic or Latino, and NHW population. In patients with recent ischemic stroke, the proportion with AF was 32.2%, 24.3%, 25%, and 24.5%, respectively. The prevalence of AF among the stroke population was approximately 7 to 10 times higher than the prevalence among the overall population for the Asian and Hispanic or Latino population, compared to approximately 5 times higher for NHW patients. The relative AF prevalence difference of the Asian and Hispanic or Latino population with the NHW population narrowed from respectively, -46% and -65%, to -22% and -24%. The study findings align with previous observational studies, revealing lower incidence and prevalence rates of AF in US minority groups. Prevalence estimates of the adult population, when routine clinical practice is assumed, exhibit higher prevalence differences compared to settings in which monitoring for AF is assumed, particularly among Asian and Hispanic or Latino subgroups.

Prognostic value of left atrial size in hypertensive African Americans undergoing stress echocardiography

BACKGROUND

Left atrial (LA) enlargement is a marker of increased risk in the general population undergoing stress echocardiography. African American (AA) patients with hypertension are known to have less atrial remodeling than whites with hypertension. The prognostic impact of LA enlargement in AA with hypertension undergoing stress echocardiography is uncertain.

AIM

To investigate the prognostic value of LA size in hypertensive AA patients undergoing stress echocardiography.

METHODS

This retrospective outcomes study enrolled 583 consecutive hypertensive AA patients who underwent stress echocardiography over a 2.5-year period. Clinical characteristics including cardiovascular risk factors, stress and echocardiographic data were collected from the electronic health record of a large community hospital. Treadmill exercise and Dobutamine protocols were conducted based on standard practices. Patients were followed for all-cause mortality. The optimal cutoff value of antero-posterior LA diameter for mortality was assessed by receiver operating characteristic analysis. Cox regression was used to determine variables associated with outcome.

RESULTS

The mean age was 57 ± 12 years. LA dilatation was present in 9% (54) of patients (LA anteroposterior ≥ 2.4 cm/m²). There were 85 deaths (15%) during 4.5 ± 1.7 years of follow-up. LA diameter indexed for body surface area had an area under the curve of 0.72 ± 0.03 (optimal cut-point of 2.05 cm/m²). Variables independently associated with mortality included age [P = 0.004, hazard ratio (HR) 1.34 (1.10-1.64)], tobacco use [P = 0.001, HR 2.59 (1.51-4.44)], left ventricular hypertrophy [P = 0.001 , HR 2.14 (1.35-3.39)], Dobutamine stress [P = 0.003, HR 2.12 (1.29-3.47)], heart failure history [P = 0.031, HR 1.76 (1.05-2.94)], LA diameter ≥ 2.05 cm/m² [P = 0.027, HR 1.73 (1.06-2.82)], and an abnormal stress echocardiogram [P = 0.033, HR 1.67 (1.04-2.68)]. LA diameter as a continuous variable was also independently associated with mortality but LA size ≥ 2.40 cm/m² was not.

CONCLUSION

LA enlargement is infrequent in hypertensive AA patients when traditional reference values are used. LA enlargement is independently associated with mortality when a lower than “normal” threshold (≥ 2.05 cm/m²) is used.

Epidemiology of Atrial Fibrillation: Geographic/Ecological Risk Factors, Age, Sex, Genetics

Atrial fibrillation is the most common arrhythmia globally. The global prevalence of atrial fibrillation is positively correlated with the sociodemographic index of different regions. Advancing age, male sex, and Caucasian race are risk factors; female sex is correlated with higher atrial fibrillation mortality worldwide likely owing to thromboembolic risk. African American ethnicity is associated with lower atrial fibrillation risk, same as Asian and Hispanic/Latino ethnicities compared with Caucasians. Atrial fibrillation may be heritable, and more than 100 genetic loci have been identified. A polygenic risk score and clinical risk factors are feasible and effective in risk stratification of incident disease.

The prevalence of atrial fibrillation on 48-hour ambulatory electrocardiography in African Americans compared to Whites: The Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

A lower prevalence of atrial fibrillation (AF), but paradoxically higher burden of cardiovascular disease risk factors, has been observed among African Americans compared to Whites in studies of AF identified by mostly 12-lead electrocardiograms (ECGs) and clinically.

METHODS

We performed 48-hour ambulatory electrocardiography (aECG) in a biracial sample of 1,193 participants in the Atherosclerosis Risk in Communities (ARIC) (mean age = 78 years, 62% African Americans, 64% female). Atrial fibrillation was identified from aECG, study visit ECGs, and discharge codes from cohort hospitalizations. We used covariate-adjusted logistic regression to estimate prevalence odds ratios (ORs) for AF in African Americans versus Whites, with adjustment for sampling and nonresponse.

RESULTS

African Americans were more likely than Whites to have hypertension and diabetes but less likely to have coronary heart disease. The prevalence of AF detected by aECG or ARIC study ECG (adjusted for age and coronary heart disease) was lower in African Americans than Whites (2.7% vs 5.0%). White men had a higher (although not significant) AF prevalence of 7.8% compared to the other race and gender groups at 2.3%-2.8%. The adjusted OR for AF was 0.49 (0.24-0.99) comparing African Americans to Whites. Findings were similar when AF was defined to include prior AF hospitalizations (OR = 0.42, 0.25-0.72). There were no significant differences by race for asymptomatic or paroxysmal AF.

CONCLUSIONS

Atrial fibrillation was less prevalent in African American than white older adults, regardless of detection method. Although overall detection of new AF cases with aECG was low, future studies should consider longer-term monitoring to characterize AF by race.

Risk Factors Influencing Outcomes of Atrial Fibrillation in ALLHAT

BACKGROUND AND AIMS

ALLHAT, a randomized, double-blind, active-controlled, multicenter clinical trial of high risk hypertensive participants, compared treatment with an ACE-inhibitor (lisinopril) or calcium channel blocker (amlodipine) with a diuretic (chlorthalidone). Primary outcome was the occurrence of fatal coronary heart disease or nonfatal myocardial infarction. For this report, post-hoc analyses were conducted to determine the contribution of baseline characteristics of participants with or without baseline or incident atrial fibrillation (AF) and atrial flutter (AFL) to stroke, heart failure (HF), coronary heart disease (CHD), and mortality outcomes.

METHODS AND RESULTS

Minnesota Coding of baseline and biennial in-trial ECGs was used to determine the 334 baseline and 537 incident AF/AFL cases, respectively participants with AF/AFL: Cox regression was used to estimate hazard ratios of presence versus absence of either baseline or incident AF/AFL (as time-dependent covariate) for occurrence of stroke, CHD, HF, or mortality, while adjusting for selected baseline characteristics. Adjusted Cox regression was used to obtain hazard ratios (HRs) for presence versus absence of selected baseline characteristics among those with and without either baseline or incident AF/AFL. After adjusting for baseline characteristics, baseline AF/AFL was associated with stroke, HF, and mortality (HRs [95% CIs] 3.18, [2.34-4.33]; 2.65 [2.02-3.49]; and 2.10 [CI, 1.73-2.55], respectively, P < 0.05). Incident AF/AFL was a significant risk factor for HF and mortality (HRs 2.80 and 2.06, respectively, P < 0.05). Risk factor profiles for clinical outcomes for those with and without baseline or incident AF/AFL were largely similar.

CONCLUSIONS

AF/AFL is a significant risk factor for stroke, HF, and mortality. Additional risk factors for these outcomes were generally similar for participants with and without baseline or incident AF/AFL.

Genetic modulation of atrial fibrillation risk in a Hispanic/Latino cohort

Atrial fibrillation (AF) is the most prevalent cardiac rhythm disorder worldwide but the underlying genetic and molecular mechanisms and the response to therapies is not fully understood. Despite a greater burden of AF risk factors in Hispanics/Latinos the prevalence of AF remains low. Over the last decade, genome-wide association studies have identified numerous AF susceptibility loci in mostly whites of European descent. The goal of this study was to determine if the top 9 single nucleotide polymorphisms (SNPs) associated with AF in patients of European descent also increase susceptibility to AF in Hispanics/Latinos. AF cases were prospectively enrolled in the University of Illinois at Chicago (UIC) AF Registry and control subjects were identified from the UIC Cohort of Patients, Family and Friends. AF cases and controls were genotyped for 9 AF risk SNPs at chromosome 1q21: rs13376333, rs6666258; chr1q24: rs3903239; chr4q25: rs2200733; rs10033464; chr10q22: rs10824026; chr14q23: rs1152591; chr16q22: rs2106261 and rs7193343. The study sample consisted of 713 Hispanic/Latino subjects including 103 AF cases and 610 controls. Among the 8 AF risk SNPs genotyped, only rs10033464 SNP at chromosome (chr) 4q25 (near PITX2) was significantly associated with development of AF after multiple risk factor adjustment and multiple testing (adj. odds ratio [OR] 2.27, 95% confidence interval [CI] 1.31–3.94; P = 3.3 x 10⁻³). Furthermore, the association remained significant when the analysis was restricted to Hispanics of Mexican descent (adj. OR 2.32, 95% CI 1.35–3.99; P = 0.002. We confirm for the first time the association between a chromosome 4q25 SNP and increased susceptibility to AF in Hispanics/Latinos. While the underlying molecular mechanisms by which the chr4q25 SNP modulates AF risk remains unclear, this study supports a genetic basis for non-familial AF in patients of Hispanic descent.

Epidemiology of atrial fibrillation

BACKGROUND

The most common type of arrhythmia in the USA and in European countries is atrial fibrillation (AF). The prevalence of AF is increasing worldwide with advances in technology, better prediction methods and increased awareness among healthcare professionals and patients.

METHODS

This article summarises the literature on the epidemiology of AF worldwide according to continents, age and ethnicity/race, and also includes the prevalence of AF in stroke patients.

RESULTS

In Australia, Europe and the USA, the current estimated prevalence of AF is about between 1% and 4%, with lower prevalence evident in Asia (0.49%-1.9%). AF prevalence is highest among Whites. In Western Europe, Australia and North America 70% of people with AF are aged >65 years, whereas the average age of AF patients in other geographical regions is often lower.

CONCLUSIONS

Although the prevalence of AF worldwide is increasing steadily, large variation can be seen between studies and countries. Further epidemiological studies should be undertaken globally, especially in Asian and African countries so that a better and more accurate picture of the incidence and prevalence of AF can be captured, to enable stroke prevention strategies to be appropriately implemented to prevent or reduce the risk of stroke, the most severe consequence of AF.

Effect of Digoxin Use Among Medicaid Enrollees With Atrial Fibrillation

BACKGROUND

Recently published analysis of contemporary atrial fibrillation (AF) cohorts showed an association between digoxin and increased mortality and hospitalizations; however, other studies have demonstrated conflicting results. Many AF cohort studies did not or were unable to examine racial differences. Our goal was to examine risk factors for hospitalizations and mortality with digoxin use in a diverse real-world AF patient population and evaluate racial differences.

METHODS AND RESULTS

We performed a retrospective cohort analysis of claims data for Medicaid beneficiaries, aged 18 to 64 years, with incident diagnosis of AF in 2008 with follow-up until December 31, 2009. We created Kaplan-Meier curves and constructed multivariable Cox proportional hazard models for mortality and hospitalization. We identified 11 297 patients with an incident diagnosis of AF in 2008, of those, 1401 (12.4%) were on digoxin. Kaplan-Meier analysis demonstrated an increased risk of hospitalization with digoxin use overall and within race and heart failure groups. In adjusted models, digoxin was associated with an increased risk of hospitalization (adjusted hazard ratio, 1.54; 95% confidence interval, 1.39-1.70) and mortality (adjusted hazard ratio, 1.50; 95% confidence interval, 1.05-2.13). Overall, blacks had a higher risk of hospitalization but similar mortality when compared with whites regardless of digoxin use. We found no significant interaction between race and digoxin use for mortality (P=0.4437) and hospitalization (P=0.7122).

CONCLUSIONS

Our study demonstrates an overall increased risk of hospitalizations and mortality with digoxin use but no racial/ethnic differences in outcomes were observed. Further studies including minority populations are needed to critically evaluate these associations.

Socioeconomic status and the development of atrial fibrillation in Hispanics, African Americans and non-Hispanic whites

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia and is associated with significant morbidity and mortality. Despite having a higher burden of traditional AF risk factors, African American and Hispanic minorities have a lower incidence of AF when compared to non-Hispanic whites, referred to as the "racial paradox."

HYPOTHESIS

Lower SES among Hispanics and African Americans may help to explain the lower incidence rates of AF compared to non-Hispanic whites.

METHODS

An electrocardiogram/electronic medical records database in New York State was interrogated for individuals free of AF for development of subsequent AF from 2000 to 2013. SES was assessed per zip code via a composite of 6 measures Z-scored to the New York State average. SES was reclassified into decile groups. Cox regression analysis controlling for all baseline differences was used to estimate the independent predictive ability of SES for AF.

RESULTS

We identified 48 631 persons (43% Hispanic, 37% African Americans, and 20% non-Hispanic white; mean age 59 years; mean follow-up of 3.2 years) of which 4556 AF cases occurred. Hispanics and African Americans had lower AF risk than whites in all SES deciles (P < 0.001 by log-rank test). Higher SES was borderline associated with lower AF risk (hazard ratio: 0.990, 95% confidence interval: 0.980-1.001, P = 0.061). P trend analysis was not significant by any race/ethnic group by SES deciles for AF.

CONCLUSIONS

Our study suggests that non-Hispanic whites were at higher risk for AF compared to nonwhites, and this was independent of SES.

The occurrence of atrial fibrillation in dialysis patients and its association with left atrium volume before and after dialysis

PURPOSE

Atrial fibrillation is a serious problem, especially in patients on dialysis. The prevalence of AF in this group of patients is higher than in general population and associated with increased mortality. The aim of this study was to assess the risk of the occurrence of atrial fibrillation related to intradialysis hypotension and left atrium volume enlargement associated with dialysis. The influence of dialysis session on: E/E', V LA, E/A, E', V RA and the width of inferior vena cava of RV was analyzed.

METHODS

This study included 40 patients on hemodialysis. Echocardiographic examination was performed to assess heart condition and function, the presence of LVH and systolic and diastolic function disturbances, LV mass, LA size, LAV, RAV, E/A, E', E/E, ejection fraction in all patients before and after dialysis. Moreover, all patients had ECG Holter continuously recording heart's rhythm before and after dialysis to assess the occurrence of atrial fibrillation related to dialysis session.

RESULTS

The analysis of differences in echocardiographic parameters before and after dialysis demonstrated significantly greater left atrium volume, right atrium volume, width of inferior vena cava and e' parameter before dialysis in comparison with post-dialysis state. Significantly higher incidence of AF after dialysis was seen. Volume of left atrium exceeding 32 mm (cutoff value) was observed significantly more often in patients before dialysis. No association was observed between left ventricle mass and left atrium volume.

CONCLUSIONS

The dialysis procedure may be a trigger for atrial fibrillation and thus AF preventive measures should be introduced in dialysis patients.

Post-discharge Follow-up Characteristics Associated With 30-Day Readmission After Heart Failure Hospitalization

BACKGROUND

Readmission within 30 days after hospitalization for heart failure (HF) is a major public health problem.

OBJECTIVE

To examine whether timing and type of post-discharge follow-up impacts risk of 30-day readmission in adults hospitalized for HF.

DESIGN

Nested matched case-control study (January 1, 2006-June 30, 2013).

SETTING

A large, integrated health care delivery system in Northern California.

PARTICIPANTS

Hospitalized adults with a primary diagnosis of HF discharged to home without hospice care.

MEASUREMENTS

Outpatient visits and telephone calls with cardiology and general medicine providers in non-emergency department and non-urgent care settings were counted as follow-up care. Statistical adjustments were made for differences in patient sociodemographic and clinical characteristics, acute severity of illness, hospitalization characteristics, and post-discharge medication changes and laboratory testing.

RESULTS

Among 11,985 eligible adults, early initial outpatient contact within 7 days after discharge was associated with lower odds of readmission [adjusted odds ratio (OR)=0.81; 95% CI, 0.70-0.94], whereas later outpatient contact between 8 and 30 days after hospital discharge was not significantly associated with readmission (adjusted OR=0.99; 95% CI, 0.82-1.19). Initial contact by telephone was associated with lower adjusted odds of 30-day readmission (adjusted OR=0.85; 95% CI, 0.69-1.06) but was not statistically significant.

CONCLUSIONS

In adults discharged to home after hospitalization for HF, outpatient follow-up with a cardiology or general medicine provider within 7 days was associated with a lower chance of 30-day readmission.

Investigation of selection bias in the association of race with prevalent atrial fibrillation in a national cohort study: REasons for Geographic And Racial Differences in Stroke (REGARDS)

PURPOSE

Atrial fibrillation (AF) is diagnosed more commonly in whites than blacks in the United States. In epidemiologic studies, selection bias could induce a noncausal positive association of white race with prevalent AF if voluntary enrollment was influenced by both race and AF status. We investigated whether nonrandom enrollment biased the association of race with prevalent self-reported AF in the US-based REasons for Geographic And Racial Differences in Stroke Study (REGARDS).

METHODS

REGARDS had a two-stage enrollment process, allowing us to compare 30,183 fully enrolled REGARDS participants with 12,828 people who completed the first-stage telephone survey but did not complete the second-stage in-home visit to finalize their REGARDS enrollment (telephone-only participants).

RESULTS

REGARDS enrollment was higher among whites (77.1%) than among blacks (62.3%) but did not differ by self-reported AF status. The prevalence of AF was 8.45% in whites and 5.86% in blacks adjusted for age, sex, income, education, and perceived general health. The adjusted white/black prevalence ratio of self-reported AF was 1.43 (95% CI, 1.32-1.56) among REGARDS participants and 1.38 (1.22-1.55) among telephone-only participants.

CONCLUSIONS

These findings suggest that selection bias is not a viable explanation for the higher prevalence of self-reported AF among whites in population studies such as REGARDS.

Racial Differences in the Prevalence and Outcomes of Atrial Fibrillation in Patients Hospitalized With Heart Failure

Previous research has shown that roughly 15% to 30% of those with heart failure (HF) develop atrial fibrillation (AF). Although studies have shown variations in the incidence of AF in patients with HF, there has been no evidence of mortality differences by race. The purpose of this study was to assess AF prevalence and inhospital mortality in patients with HF among different racial groups in the United States. Using the National Inpatient Sample registry, the largest publicly available all-payer inpatient care database representing >95% of the US inpatient population, we analyzed subjects hospitalized with a primary diagnosis of HF from 2001 to 2011 (n = 11,485,673) using the International Classification of Diseases, Ninth Edition (ICD 9) codes 428.0-0.1, 428.20-0.23, 428.30-0.33, 428.40-0.43, and 428.9; patients with AF were identified using the ICD 9 code 427.31. We assessed prevalence and mortality among racial groups. Using logistic regression, we examined odds of mortality adjusted for demographics and co-morbidity using Elixhauser co-morbidity index. We also examined utilization of procedures by race. Of the 11,485,673 patients hospitalized with HF in our study, 3,939,129 (34%) had AF. Patients with HF and AF had greater inhospital mortality compared with those without AF (4.6% vs 3.3% respectively, p <0.0001). Additionally, black, Hispanic, Asian, and white patients with HF and AF had a 24%, 17%, 13%, and 6% higher mortality, respectively, than if they did not have AF. Among patients with HF and AF, minority racial groups had underutilization of catheter ablation and cardioversion compared with white patients. In conclusion, minority patients with HF and AF had a disproportionately higher risk of inpatient death compared with white patients with HF. We also found a significant underutilization of cardioversion and catheter ablation in minority racial groups compared with white patients.

Impact of sex and ethnicity on arrhythmic risk

Substantial differences in the risk of common arrhythmia syndromes exist between men and women, as well as in varying ethnic/racial groups. For example, despite an overall lower risk of sudden death and atrial fibrillation in women compared with men, women have longer QT intervals and a higher risk of torsades de pointes due to antiarrhythmic drugs and worse outcomes associated with atrial fibrillation. An ethnicity-related paradox in atrial fibrillation epidemiology is apparent; despite a higher prevalence of medical comorbidities such as hypertension, diabetes, and prolonged PR interval, blacks, Hispanics, and Asians have a lower risk of atrial fibrillation than whites. In this promising era of genomic medicine, an improved understanding of epidemiology and phenotype holds the potential for revealing novel therapeutic targets and preventing disease.

Rates of Atrial Fibrillation in Black Versus White Patients With Pacemakers

BACKGROUND

Black US residents experience higher rates of ischemic stroke than white residents but have lower rates of clinically apparent atrial fibrillation (AF), a strong risk factor for stroke. It is unclear whether black persons truly have less AF or simply more undiagnosed AF.

METHODS AND RESULTS

We obtained administrative claims data from state health agencies regarding all emergency department visits and hospitalizations in California, Florida, and New York. We identified a cohort of patients with pacemakers, the regular interrogation of which reduces the likelihood of undiagnosed AF. We compared rates of documented AF or atrial flutter at follow-up visits using Kaplan-Meier survival statistics and Cox proportional hazards models adjusted for demographic characteristics and vascular risk factors. We identified 10 393 black and 91 380 white patients without documented AF or atrial flutter before or at the index visit for pacemaker implantation. During 3.7 (±1.8) years of follow-up, black patients had a significantly lower rate of AF (21.4%; 95% CI 19.8-23.2) than white patients (25.5%; 95% CI 24.9-26.0). After adjustment for demographic characteristics and comorbidities, black patients had a lower hazard of AF (hazard ratio 0.91; 95% CI 0.86-0.96), a higher hazard of atrial flutter (hazard ratio 1.29; 95% CI 1.11-1.49), and a lower hazard of the composite of AF or atrial flutter (hazard ratio 0.94; 95% CI 0.88-99).

CONCLUSIONS

In a population-based sample of patients with pacemakers, black patients had a lower rate of AF compared with white patients. These findings indicate that the persistent racial disparities in rates of ischemic stroke are likely to be related to factors other than undiagnosed AF.

Almanac 2015: atrial fibrillation research in Heart

Atrial fibrillation continues to attract interest in the cardiovascular community and in Heart. Over 60 original research and review papers published in Heart in 2014–2015 cover various aspects of atrial fibrillation, from associated conditions and precipitating factors to new approaches to management. Here, we provide an overview of articles on atrial fibrillation published in Heart in 2014–2015, highlighting new developments, emerging concepts and novel approaches to treatment.

Validation of the Framingham Heart Study and CHARGE-AF Risk Scores for Atrial Fibrillation in Hispanics, African-Americans, and Non-Hispanic Whites

A risk score for atrial fibrillation (AF) has been developed by the Framingham Heart Study and Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE)-AF consortium. However, validation of these risk scores in an inner-city population is uncertain. Thus, a validation model was built using the Framingham Risk Score for AF and CHARGE-AF covariates. An in and outpatient electrocardiographic database was interrogated from 2000 to 2013 for the development of AF. Patients were included if their age was >45 and <95 years, had <10-year follow-up, if their initial electrocardiogram was without AF, had ≥ 2 electrocardiograms, and declared a race and/or ethnicity as non-Hispanic white, African-American, or Hispanic. For the Framingham Heart Study, 49,599 patients met inclusion criteria, of which 4,860 developed AF. Discrimination analysis using area under the curve (AUC) for original risk equations: non-Hispanic white AUC = 0.712 (95% confidence interval [CI] 0.694 to 0.731), African-American AUC = 0.733 (95% CI 0.716 to 0.751), and Hispanic AUC = 0.740 (95% CI 0.723 to 0.757). For the CHARGE-AF, 45,571 patients met inclusion criteria, of which 4,512 developed AF. Non-Hispanic white AUC = 0.673 (95% CI 0.652 to 0.694), African-American AUC = 0.706 (95% CI 0.685 to 0.727), and Hispanic AUC = 0.711 (95% CI 0.691 to 0.732). Calibration analysis showed qualitative similarities between cohorts. In conclusion, this is the first study to validate both the Framingham Heart Study and CHARGE-AF risk scores in both a Hispanic and African-American cohort. All models predicted AF well across all race and ethnic cohorts.

Association of rs17042171 with chromosome 4q25 with atrial fibrillation in Chinese Han populations

Objective:

A recent genome-wide association study (GWAS) identified a susceptibility single nucleotide polymorphism (SNP), rs17042171 on 4q25 for atrial fibrillation (AF). The aim of the present study was to investigate whether this association between rs17042171 and AF also exists in Chinese Han populations.

Methods:

It was a case-control study. We enrolled a total of 1,593 Chinese Han origin individuals in the study, including 597 AF patients and 996 AF-free controls. Genotyping was performed using the TaqMan allelic discrimination Assay. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in logistic regression models.

Results:

There was strongly significant difference between AF patients and control subjects regarding rs17042171 assumption of additive model (OR=2.20, 95% CI: 1.88-2.57, p=2.00 × 10^-22), dominant model (OR=2.99; 95% CI: 2.19-4.09; p=6.47 × 10^-12) and a recessive (OR=2.75; 95% CI: 2.21-3.43; p=1.30 10^-19). In the stratification analysis based on age, gender, hypertension, diabetes and coronary artery disease, there was no significant difference of the associations for rs17042171 among the subgroups.

Conclusion:

Our results indicated that rs17042171 confers an increased risk of AF in Chinese Han Populations and expanded the association to non-European ancestry populations for the first time. (Anatol J Cardiol 2016; 16: 165-9)

Atrial Fibrillation and Colonic Neoplasia in African Americans

Background

Colorectal cancer (CRC) and atrial fibrillation/flutter (AF) share several risk factors including increasing age and obesity. However, the association between CRC and AF has not been thoroughly examined, especially in African Americans. In this study we aimed to assess the prevalence of AF and its risk factors in colorectal neoplasia in an African American.

Methods

We reviewed records of 527 African American patients diagnosed with CRC and 1008 patients diagnosed with benign colonic lesions at Howard University Hospital from January 2000 to December 2012. A control group of 731 hospitalized patients without any cancer or colonic lesion were randomly selected from the same time and age range, excluding patients who had diagnosis of both CRC and/or adenoma. The presence or absence of AF was based upon ICD-9 code documentation. The prevalence of AF in these three groups was compared by multivariate logistic regression.

Results

The prevalence of AF was highest among CRC patients (10%) followed by adenoma patients (7.2%) then the control group (5.4%, P for trend = 0.002). In the three groups of participants, older age (P<0.008) and heart failure (P<0.001) were significantly associated with higher risk of AF. After adjusting for these risk factors, CRC (OR: 1.4(95%CI):0.9–2.2, P = 0.2) and adenoma (OR: 1.1(95%CI):0.7–1.6, P = 0.7) were not significantly associated AF compared to control group.

Conclusions

AF is highly prevalent among CRC patients; 1 in 10 patients had AF in our study. The predictors of AF in CRC was similar to that in adenoma and other patients after adjustment for potential confounders suggesting that the increased AF risk in CRC is explained by higher prevalence of AF risk factors.

Effect of race on outcomes (stroke and death) in patients >65 years with atrial fibrillation

Atrial fibrillation (AF) is associated with stroke and death. We sought to determine whether there are any racial differences in the outcomes of death and stroke in patients with AF. We used Medicare administrative data from January 1, 2010, to December 31, 2011, to identify 517,941 patients with newly diagnosed AF. Of these, 452,986 patients (87%) were non-Hispanic white, 36,425 (7%) were black, and 28,530 (6%) were Hispanic. The association between race and outcomes of death and stroke were measured using Cox proportional hazard models. Over a median follow-up period of 20.3 months, blacks had a significantly higher hazard of death (hazard ratio [HR] = 1.46; 95% confidence interval [CI] 1.43 to 1.48; p <0.001) and stroke (HR = 1.66; 95% CI 1.57 to 1.75; p <0.001), compared with white patients. After controlling for pre-existing co-morbidities, the higher hazard of death in blacks was eliminated (HR 0.95; 95% CI 0.93 to 0.96; p <0.001) and the relative hazard of stroke was reduced (HR = 1.46; 95% CI 1.38 to 1.55; p <0.001). Similarly, Hispanics had a higher risk of death (HR = 1.11; 95% CI 1.09 to 1.14; p <0.001) and stroke (HR = 1.21; 95% CI 1.13 to 1.29; p <0.001) compared with whites. The relative hazard of death was lower in Hispanics (HR 0.82; 95% CI 0.80 to 0.84; p <0.001) compared with whites, after controlling for pre-existing co-morbidities, and the relative hazard of stroke was also attenuated (HR = 1.11; 95% CI 1.03 to 1.18; p <0.001). In conclusion, in patients >65 years with newly diagnosed AF, the risks of death and stroke are higher in blacks and Hispanics compared with whites. The increased risk was eliminated or significantly reduced after adjusting for pre-existing co-morbidities. AF may be a marker for underlying co-morbidities in black and Hispanic patients who may be at a higher mortality risk.

Inflammation as a Mediator of the Association Between Race and Atrial Fibrillation: Results from the Health, Aging, and Body Composition Study

BACKGROUND

Despite a lower prevalence of established atrial fibrillation (AF) risk factors, Whites exhibit substantially higher rates of this arrhythmia compared to Blacks. The mechanism underlying this observation is not known. Both inflammation and obesity are risk factors for AF, and adipose tissue is a known contributor to systemic inflammation.

OBJECTIVES

We sought to determine the degree to which racial differences in AF risk are explained by differences in inflammation and adiposity.

METHODS

Baseline serum inflammatory biomarker concentrations and abdominal adiposity (assessed by computed tomography) were quantified in a subset of Black and White participants without prevalent AF in the Health, Aging, and Body Composition (Health ABC) Study. Participants were prospectively followed for the diagnosis of AF using study ECGs and Medicare claims data. Cox proportional hazards models were used to determine the adjusted relative hazard of incident AF between races before and after biomarker adjustment.

RESULTS

Among 2,768 participants (43% Black), 721 developed incident AF over a median follow up of 10.9 years. White race was associated with a heightened adjusted risk of incident AF (HR 1.55, 95% CI 1.30 to 1.84, p < 0.001). Abdominal adiposity was not associated with AF when added to the adjusted model. Among the studied biomarkers, adiponectin, TNF-α, TNF-α SR I, and TNF-α SR II concentrations were each higher among Whites and independently associated with a greater risk of incident AF. Together, these inflammatory cytokines mediated 42% (95% CI 15 to 119%, p = 0.004) of the adjusted race-AF association.

CONCLUSIONS

Systemic inflammatory pathways significantly mediate the heightened risk of AF among Whites. The higher level of systemic inflammation and concomitant increased AF risk in Whites is not explained by racial differences in abdominal adiposity or the presence of other pro-inflammatory cardiovascular comorbidities.

Atrial fibrillation incidence and risk factors in relation to race-ethnicity and the population attributable fraction of atrial fibrillation risk factors: the Multi-Ethnic Study of Atherosclerosis

PURPOSE

We studied incident atrial fibrillation (AF) in the prospective community-based Multi-Ethnic Study of Atherosclerosis (MESA). Reportedly, non-Hispanic blacks (NHBs) have a lower AF burden compared with their non-Hispanic white (NHW) counterparts. Information on the epidemiology of AF in Hispanic and Asian populations is much more limited.

METHODS

We excluded participants with a history of AF at enrollment. A total of 6721 MESA participants were monitored for the first AF event ascertained according to hospital discharge International Classification of Diseases, Ninth Revision, codes. Age- and sex-adjusted incidence rates (IRs) of AF were calculated per 1000 person-years of observation. IR ratios were calculated using NHWs as the reference group. Age- and sex-adjusted population attributable fractions (PAFs) of established modifiable AF risk factors were ascertained.

RESULTS

In the MESA cohort, 47.2% was male; at baseline, 25.7% had hypertension; 12.5% had diabetes. Three hundred five incident hospitalized AF events occurred over a mean follow-up of 7.3 years. Age- and sex-adjusted IRs and IR ratios showed that overall AF incidence was significantly lower among Hispanics, NHBs and Chinese compared with NHWs (all P < .001). Among participants 65 years of age or greater, Hispanics, Chinese, and blacks had significantly lower AF incidence than NHWs (all P ≤ .01), but IRs were similar among participants under age 65 years. The PAF for smoking was 27% among NHBs but lower among other race-ethnic groups. Among NHWs, the PAF for hypertension was 22.2%, but this was higher among NHBs (33.1%), Chinese (46.3%), and Hispanics (43.9%).

CONCLUSIONS

Overall, the incidence of hospitalized AF was significantly lower in Hispanics, NHBs, and Chinese than in NHWs. A larger proportion of AF events appear to be attributable to hypertension among nonwhite populations compared with NHWs.

Atrial fibrillation in Indigenous and non-Indigenous Australians: a cross-sectional study

OBJECTIVE

To examine the prevalence of atrial fibrillation (AF) and cardiac structural characteristics in Indigenous and non-Indigenous Australians.

DESIGN

Retrospective cross-sectional study linking clinical, echocardiography and administrative databases over a 10-year period.

SETTING

A tertiary, university teaching hospital in Adelaide, Australia.

PARTICIPANTS

Indigenous and non-Indigenous Australians.

MAIN OUTCOME MEASURES

AF prevalence and echocardiographic characteristics.

RESULTS

Indigenous Australians with AF were significantly younger compared to non-Indigenous Australians (55±13 vs 75±13 years, p<0.001). As a result, racial differences in AF prevalence and left atrial diameter varied according to age. In those under 60 years of age, Indigenous Australians had a significantly greater AF prevalence (2.57 vs1.73%, p<0.001) and left atrial diameters (39±7 vs 37±7 mm, p<0.001) compared to non-Indigenous Australians. In those aged 60 years and above, however, non-Indigenous Australians had significantly greater AF prevalence (9.26 vs 4.61%, p<0.001) and left atrial diameters (39±7 vs 37±7 mm, p<0.001). Left ventricular ejection fractions were less in Indigenous Australians under 60 years of age (49±14 vs 55±11%, p<0.001) and not statistically different in those aged 60 years and above (47±11 vs 52±13, p=0.074) compared to non-Indigenous Australians. Despite their younger age, Indigenous Australians with AF had similar or greater rates of cardiovascular comorbidities than non-Indigenous Australians with AF.

CONCLUSIONS

Young Indigenous Australians have a significantly greater prevalence of AF than their non-Indigenous counterparts. In contrast, older non-Indigenous Australians have a greater prevalence of AF compared to their Indigenous counterparts. These observations may be mediated by age-based differences in comorbid cardiovascular conditions, left atrial diameter and left ventricular ejection fraction. Our findings suggest that AF is likely to be contributing to the greater burden of morbidity and mortality experienced by young Indigenous Australians. Further study is required to elucidate whether strategies to prevent and better manage AF in Indigenous Australians may reduce this burden.

Socioeconomic status and the incidence of atrial fibrillation in whites and blacks: the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

No previous studies have examined the interplay among socioeconomic status, sex, and race with the risk of atrial fibrillation (AF).

METHODS AND RESULTS

We prospectively followed 14 352 persons (25% black, 75% white, 55% women, mean age 54 years) who were free of AF and participating in the Atherosclerosis Risk in Communities (ARIC) study. Socioeconomic status was assessed at baseline (1987-1989) through educational level and total family income. Incident AF through 2009 was ascertained from electrocardiograms, hospitalizations, and death certificates. Cox regression was used to estimate hazard ratios and 95% CIs of AF for education and family income. Interactions were tested between socioeconomic status and age, race, or sex. Over a median follow-up of 20.6 years, 1794 AF cases occurred. Lower family income was associated with higher AF risk (hazard ratio 1.45, 95% CI 1.27 to 1.67 in those with income less than $25 000 per year compared with those with $50 000 or more per year). The association between education and AF risk varied by sex (P=0.01), with the lowest education group associated with higher AF risk in women (hazard ratio 1.88, 95% CI 1.55 to 2.28) but not in men (hazard ratio 1.15, 95% CI 0.97 to 1.36) compared with the highest education group. Adjustment for cardiovascular risk factors attenuated the associations. There were no interactions with race or age. Blacks had lower AF risk than whites in all income and education groups.

CONCLUSIONS

Lower family income was associated with a higher AF risk overall, whereas the impact of education on AF risk was present only in women. Differences in socioeconomic status do not explain the lower risk of AF in blacks compared with whites.

The paradox of atrial fibrillation in African Americans

The reported lower prevalence and incidence of atrial fibrillation (AF) despite the higher prevalence of AF risk factors in African Americans compared to Caucasian whites has been referred to as the paradox of AF in African Americans. In this report we highlight this paradox and address potential explanations using data from several US populations studies. These possible explanations include limited methodology to detect AF patterns that are harder to detect (e.g. paroxysmal/intermittent AF or atrial flutter) coupled with the possibility of African Americans having more of these patterns, differential access to health care with African Americans having less access and subsequently less detected AF, survival bias with Caucasian whites living longer and subsequently having more AF, and finally differential impact of AF risk factors with Caucasian whites being more affected or African Americans less affected by AF risk factors whether this is genetically determined or via other unknown predispositions.

Racial differences in incident atrial fibrillation among hypertensive patients during antihypertensive therapy

BACKGROUND

Blacks have a higher prevalence of risk factors for atrial fibrillation (AF), such as hypertension, obesity, and heart failure, than nonblacks. Although population-based studies have demonstrated a lower prevalence and incidence of AF in blacks, the relationship of incident AF to race among hypertensive patients undergoing blood pressure lowering has been less extensively examined.

METHODS

Incident AF was examined in 518 black and 8,313 nonblack hypertensive patients with electrocardiographic left ventricular hypertrophy (LVH) with no history of AF in sinus rhythm on their baseline electrocardiogram, who were randomly assigned to losartan- or atenolol-based treatment.

RESULTS

During a mean of 4.7±1.1 years of follow-up, new-onset AF occurred in 701 patients (7.9%); 5-year AF incidence was significantly lower in black than nonblack patients (6.1 vs. 8.3%; P = 0.03). In univariable Cox analyses, black race was associated with a 37% lower risk of new AF (hazard ratio (HR) = 0.63; 95% confidence interval (CI) = 0.45-1.00; P = 0.05). In multivariable Cox analyses adjusting for randomized treatment, age, sex, diabetes, history of heart failure, myocardial infarction, ischemic heart disease, stroke, peripheral vascular disease, smoking status, baseline body mass index, serum total and high-density lipoprotein cholesterol, creatinine, glucose, and urine albumin/creatinine ratio as standard risk factors, and for incident myocardial infarction, in-treatment heart rate, systolic and diastolic pressure, Cornell product, and Sokolow-Lyon voltage LVH treated as time-varying covariables, black race remained associated with a 45% decreased risk of developing new AF (HR = 0.55; 95% CI = 0.35-0.87; P = 0.01).

CONCLUSIONS

Incident AF is substantially less common among black than nonblack hypertensive patients.

Performance of claims-based algorithms for identifying heart failure and cardiomyopathy among patients diagnosed with breast cancer

BACKGROUND

Cardiotoxicity is a known complication of certain breast cancer therapies, but rates come from clinical trials with design features that limit external validity. The ability to accurately identify cardiotoxicity from administrative data would enhance safety information.

OBJECTIVE

To characterize the performance of clinical coding algorithms for identification of cardiac dysfunction in a cancer population.

RESEARCH DESIGN

We sampled 400 charts among 6460 women diagnosed with incident breast cancer, tumor size ≥ 2 cm or node positivity, treated within 8 US health care systems between 1999 and 2007. We abstracted medical records for clinical diagnoses of heart failure (HF) and cardiomyopathy (CM) or evidence of reduced left ventricular ejection fraction. We then assessed the performance of 3 different International Classification of Diseases, 9th Edition (ICD-9)-based algorithms.

RESULTS

The HF/CM coding algorithm designed a priori to balance performance characteristics provided a sensitivity of 62% (95% confidence interval, 40%-80%), specificity of 99% (range, 97% to 99%), positive predictive value (PPV) of 69% (range, 45% to 85%), and negative predictive value (NPV) of 98% (range, 96% to 99%). When applied only to incident HF/CM (ICD-9 codes and gold standard diagnosis both occurring after breast cancer diagnosis) in patients exposed to anthracycline and/or trastuzumab therapy, the PPV was 42% (range, 14% to 76%).

CONCLUSIONS

Claims-based algorithms have moderate sensitivity and high specificity for identifying HF/CM among patients with invasive breast cancer. As the prevalence of HF/CM among the breast cancer population is low, ICD-9 codes have high NPV but only moderate PPV. These findings suggest a significant degree of misclassification due to HF/CM overcoding versus incomplete clinical documentation of HF/CM in the medical record.

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.

Incident atrial fibrillation among Asians, Hispanics, blacks, and whites

BACKGROUND

Because the association between atrial fibrillation (AF) and race has only been rigorously compared in population-based studies that dichotomized participants as white or black, it is unclear whether white race confers elevated AF risk or black race affords AF protection.

METHODS AND RESULTS

The Healthcare Cost and Utilization Project was used to identify patients receiving hospital-based care in California between January 1, 2005 and December 31, 2009. The association between race and incident AF was examined using Cox proportional hazards models. Interaction analyses were performed to elucidate the mechanism underlying the race-AF association. Among 13 967 949 patients, 375 318 incident AF episodes were observed over a median 3.2 (interquartile range 1.8-4.3) years. In multivariable Cox models adjusting for patient demographics and established AF risk factors, blacks (hazard ratio, 0.84; 95% confidence interval, 0.82-0.85; P<0.001), Hispanics (hazard ratio, 0.78; 95% confidence interval, 0.77-0.79; P<0.001), and Asians (hazard ratio, 0.78; 95% confidence interval, 0.77-0.79; P<0.001) each exhibited a lower AF risk compared with whites. AF risk among whites was disproportionately higher in the absence of acquired cardiovascular risk factors and diminished or reversed in the presence of comorbid diseases. Although Hispanics and Asians also had a lower adjusted risk of incident atrial flutter compared with whites, the risk of flutter was significantly higher among blacks.

CONCLUSIONS

In a large hospital-based cohort, whites have an increased risk of AF whether compared with blacks, Asians, or Hispanics. The heightened AF risk among whites is most pronounced in the absence of cardiovascular comorbidities.

Temporal relationship and prognostic significance of atrial fibrillation in heart failure patients with preserved ejection fraction: a community-based study

BACKGROUND

In patients with heart failure and preserved ejection fraction (HFpEF), atrial fibrillation (AF) may predate, concur with, or develop after HFpEF diagnosis. We sought to define the temporal relationship between AF and HFpEF, to identify factors associated with AF, and to determine the prognostic impact of prevalent and incident AF in HFpEF.

METHOD AND RESULTS

From 1983 to 2010, 939 Olmsted County, Minnesota, residents (age, 77±12 years; 61% female) newly diagnosed with HFpEF (EF ≥0.50) were evaluated. Baseline rhythm classification included prior AF (>3 months before HFpEF diagnosis), concurrent AF (±3 months), or sinus rhythm. Incident AF (>3 months after HFpEF diagnosis) and all-cause mortality were ascertained through February 2012. Prior AF (29%) and concurrent AF (23%) were associated with older age, higher brain-type natriuretic peptide, and larger left atrial volume index at HFpEF diagnosis compared with sinus rhythm. Of HFpEF patients in sinus rhythm at diagnosis, 32% developed AF over a median follow-up of 3.7 years (interquartile range, 1.5-6.7 years; 69 events per 1000 person-years). Age and diastolic dysfunction were positively and statin use was inversely associated with incident AF. With no AF used as the referent, prior or concurrent AF (combined hazard ratio, 1.3; 95% confidence interval, 1.0-1.6; P=0.03) and incident AF, modeled as a time-dependent covariate (hazard ratio, 2.1; 95% confidence interval, 1.4-3.0; P<0.001), were independently associated with death after adjustment for pertinent covariates.

CONCLUSIONS

AF occurs in two thirds of HFpEF patients at some point in the natural history and confers a poor prognosis. Further study is required to determine whether intervention for AF may improve outcomes or if statin use can prevent AF in HFpEF.

Association of aldosterone synthase polymorphism (CYP11B2 -344T>C) and genetic ancestry with atrial fibrillation and serum aldosterone in African Americans with heart failure

The objective of this study was to examine the extent to which aldosterone synthase genotype (CYP11B2) and genetic ancestry correlate with atrial fibrillation (AF) and serum aldosterone in African Americans with heart failure. Clinical data, echocardiographic measurements, and a genetic sample for determination of CYP11B2 -344T>C (rs1799998) genotype and genetic ancestry were collected from 194 self-reported African Americans with chronic, ambulatory heart failure. Genetic ancestry was determined using 105 autosomal ancestry informative markers. In a sub-set of patients (n = 126), serum was also collected for determination of circulating aldosterone. The CYP11B2 -344C allele frequency was 18% among the study population, and 19% of patients had AF. Multiple logistic regression revealed that the CYP11B2 -344CC genotype was a significant independent predictor of AF (OR 12.7, 95% CI 1.60-98.4, p = 0.0150, empirical p = 0.011) while holding multiple clinical factors, left atrial size, and percent European ancestry constant. Serum aldosterone was significantly higher among patients with AF (p = 0.036), whereas increased West African ancestry was inversely correlated with serum aldosterone (r = -0.19, p = 0.037). The CYP11B2 -344CC genotype was also overrepresented among patients with extreme aldosterone elevation (≥90th percentile, p = 0.0145). In this cohort of African Americans with chronic ambulatory heart failure, the CYP11B2 -344T>C genotype was a significant independent predictor of AF while holding clinical, echocardiographic predictors, and genetic ancestry constant. In addition, increased West African ancestry was associated with decreased serum aldosterone levels, potentially providing an explanation for the lower risk for AF observed among African Americans.

The global burden of atrial fibrillation and stroke: a systematic review of the epidemiology of atrial fibrillation in regions outside North America and Europe

BACKGROUND

Although atrial fibrillation (AF) is accepted as the most common sustained cardiac arrhythmia, most published epidemiologic studies focus on predominantly white populations in North America or Europe, and information on AF in nonwhite populations is scarce. The objective of this study was to undertake a systematic review of the published literature on the epidemiology of AF in other regions.

METHODS

Systematic literature searches (MEDLINE; 1990-2010) identified epidemiologic studies reporting on the prevalence or incidence of AF, stroke in AF, risk factors for AF, or the use of antithrombotic therapy in countries outside North America and Europe. This report presents a descriptive analysis of the data; no meta-analysis was planned.

RESULTS

Many of the 38 articles identified were from the Far East, although Australia, New Zealand, the Middle East, and South America were also represented. The reported prevalence of AF varied among countries, with different ranges in community- and hospital-based studies (0.1%-4% and 2.8%-14%, respectively). The use of anticoagulant therapy varied widely among countries and studies, as did the reported prevalence of stroke in patients with AF (2.8%-24.2%).

CONCLUSIONS

High-quality epidemiologic studies are clearly required to improve understanding of the worldwide burden of AF and stroke in AF. Major improvements in the provision of thromboprophylaxis are also needed in many countries, given the high proportion of untreated patients who are, hence, at risk of stroke.

Risk of stroke or systemic embolism in atrial fibrillation patients treated with warfarin: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Although oral anticoagulants (OACs) are highly effective in reducing stroke risk in atrial fibrillation, some patients still sustain stroke despite being on an OAC. Our aim was to identify the risk factors that contribute to stroke risk in atrial fibrillation, although patients were taking OACs in a clinical trial setting.

METHODS

We identified contemporary clinical trials that investigated OACs in patients with atrial fibrillation. Event rates per year from each study and pooled event rates and relative risks, all with a 95% confidence interval, were calculated. Statistical heterogeneity was assessed using the I(2) test.

RESULTS

Six trials were included in the meta-analysis, with a total of 58 883 patients randomized. Characteristics associated with a higher relative risk of stroke while on an OAC included age ≥ 75 years (relative risk, 1.46 [95% confidence interval, 1.25-1.69]), female sex (1.30 [1.15-1.49]), previous stroke/transient ischemic attack (1.85 [1.32-2.60]), vitamin K-antagonist naive status (for vitamin K antagonist experienced, 0.85 [0.74-0.97]), moderate and severe renal impairment (1.54 [1.30-1.81] and 2.22 [1.85-2.66], respectively, compared with normal renal function), previous aspirin use (1.19 [1.04-1.37]), Asian race (1.70 [1.42-2.03]), and a CHADS2 score of ≥ 3 (1.64 [1.18-2.27]).

CONCLUSIONS

Stroke rates are higher on OACs with some patient clinical characteristics, that is, older age, female sex, previous stroke/transient ischemic attack, vitamin K-antagonist naive status, renal impairment, previous aspirin use, and higher CHADS2 score. The identified risk factors for stroke while on an OAC could potentially be used to consider a risk assessment tool to flag up high-risk patients while on an OAC (in this case, warfarin). Whether these risk factors apply to novel OACs is uncertain.

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.

Correlation of CHADS2 and CHA2DS2-VASc scores with transesophageal echocardiography risk factors for thromboembolism in a multiethnic United States population with nonvalvular atrial fibrillation

BACKGROUND

The aims of this study were to evaluate the relationship of the CHA(2)DS(2)-VASc score and risk categories with transesophageal echocardiographic (TEE) risk factors for thromboembolism and to compare the CHA(2)DS(2)-VASc and CHADS(2) risk stratification schemes with respect to their ability to predict these risk factors in a multiethnic US population with nonvalvular atrial fibrillation.

METHODS

Transesophageal echocardiograms of 167 patients (mean age, 66.3 ± 11.6 years; 146 men [87%]; 100 whites [60%]; 40 Hispanics [24%]; 27 blacks [16%]) with nonvalvular atrial fibrillation were retrospectively reviewed for smoke, sludge, thrombus, and left atrial appendage (LAA) emptying velocity ≤20 cm/sec. The patients' CHA(2)DS(2)-VASc and CHADS(2) risk scores and categories were also calculated.

RESULTS

Any LAA abnormality, smoke, sludge, thrombus, and abnormal LAA emptying velocity were present in 45%, 38%, 13%, 3%, and 22% of patients, respectively. Heart failure (P < .001), age (P < .001 for age ≥75 vs ≤64 years, P = .013 for age 65-74 vs ≤64 years), and diabetes (P = .019) were independent predictors of LAA abnormalities, while ethnicity was not. The prevalence of TEE risk factors for thromboembolism increased with increasing CHA(2)DS(2)-VASc score and risk category. The CHADS(2) risk categories of 35 patients (21%) were upgraded by the CHA(2)DS(2)-VASc scheme. Using the latter scheme, fewer patients were classified as at intermediate risk compared with the CHADS(2) system (21 [13%] vs 46 [28%]). Patients classified as at low risk by either scheme had almost no TEE risk factors. Of 30 intermediate-risk patients by CHADS(2) score upgraded to high risk using CHA(2)DS(2)-VASc score, eight (27%) had at least one TEE risk factor for thromboembolism. C-statistics, sensitivity, and specificity for predicting any LAA abnormality were 0.607 (95% confidence interval, 0.549-0.665), 92.0%, and 28.9% for CHA(2)DS(2)-VASc score and 0.685 (95% confidence interval, 0.615-0.755), 81.3%, and 54.2% for CHADS(2) score.

CONCLUSIONS

CHA(2)DS(2)-VASc score is associated with TEE risk factors for thromboembolism in a multiethnic US population. Compared with CHADS(2) score, it has increased sensitivity, decreased specificity, and lower ability for predicting TEE risk factors in this population.

Atrial fibrillation or flutter on initial electrocardiogram is associated with worse outcomes in patients admitted for worsening heart failure with reduced ejection fraction: findings from the EVEREST Trial

BACKGROUND

Heart failure (HF) complicated by atrial fibrillation/flutter (AF/AFL) is associated with worse outcomes. However, the clinical profile and outcomes of patients following hospitalization for HF with AF/AFL on initial electrocardiogram (ECG) has not been well studied.

METHODS

EVEREST was a randomized trial of vasopressin-2 receptor blockade, in addition to standard therapy, in 4133 patients hospitalized with HF with ejection fraction ≤40%. A post hoc analysis was performed comparing the clinical characteristics and outcomes [all-cause mortality and cardiovascular mortality/HF hospitalization] of patients with AF/AFL versus sinus rhythm (SR) on baseline ECG, which were centrally analyzed. Times to events were compared using log-rank tests and Cox regression models.

RESULTS

Of the 4133 patients, 1195 (29%) were classified with AF/AFL and 2071(50%) with SR. The remaining patients (21%) were excluded because ECGs were unavailable (n = 106), rhythm was paced (n = 727), or junctional/other supraventricular (n = 34). AF/AFL patients were older, with increased weight, faster heart rate, higher blood urea nitrogen, and natriuretic peptide levels compared to SR patients. Anticoagulation was prescribed in 67% of AF/AFL patients on discharge. AF/AFL patients were less likely to receive β-blockers or angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (all P < .05). After risk adjustment, AF/AFL was associated with increased mortality (hazard ratio 1.23; 95% CI, 1.04-1.46) and cardiovascular mortality/HF hospitalization (hazard ratio 1.26; 95% CI, 1.07-1.47).

CONCLUSION

AF/AFL on initial ECG in patients hospitalized with HF with reduced ejection fraction is associated with lower use of evidence-based therapies and increased mortality and rehospitalization compared to patients in SR.

New advances in the genetic basis of atrial fibrillation

Over the past decade, compelling evidence has emerged from population-based studies to suggest that AF is a heritable disease. More recently, we have begun to elucidate the genetic substrate underlying AF. Genome-wide association studies (GWAS) have led to the identification of multiple risk loci that confer increased susceptibility to the arrhythmia. These loci harbor intriguing candidate genes including those encoding ion channels, transcription factors, and signaling molecules. Current efforts are ongoing to functionally validate the role of these genes in disease pathogenesis. In the future, novel genotyping technologies such as exome sequencing and whole-genome sequencing promise to uncover a greater proportion of the heritability underlying AF. In this article we review recent advances in AF genetics research and discuss future developments in the field.

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.

Secular Trends, Treatments, and Outcomes of Middle Eastern Arab and South Asian Patients Hospitalized With Atrial Fibrillation

A prospective registry was made of all patients hospitalized with atrial fibrillation (AF) in the State of Qatar from 1991 to 2010. Clinical characteristics, management, and outcomes were compared according to ethnicity (Middle Eastern Arab vs South Asian). During this 20-year period, 2857 Arabs and 548 Asians were hospitalized for AF. Arabs were 9 years older and more likely to have hypertension, diabetes mellitus (DM), chronic renal impairment, and dyslipidemia than the Asians. Valvular heart disease and acute coronary syndromes were more common among Asians, while congestive heart failure was more common in Arabs. The overall inhospital mortality was lower in Asians than that of Arabs, while stroke rates were comparable. There was an increase in the prevalence of DM and hypertension in both the groups in the latter years of the study period, but there was no change in mortality trends. Our findings underscore the need to study AF according to ethnicity.