Novel risk factors for atrial fibrillation: useful for risk prediction and clinical decision making?

Atrial fibrillation in Black American patients: A review of genetics, risk factors, and outcomes

Atrial fibrillation (AF), the most common arrhythmia in the United States, affects 6 million Americans, with numbers projected to increase to 12 million by 2030. A racial paradox difference in the incidence and prevalence of AF exists between Black and White Americans. Black Americans are less prone than White Americans to development of AF, but they display a higher burden of modifiable risk factors for cardiovascular disease and higher rates of ischemic stroke. Data pertaining to the American Heart Association Life's Simple 7 (LS7) health metrics show that Black Americans have suboptimal LS7 scores compared with White Americans on average despite lower genetic predisposition to AF. This trend suggests the impact of cardiovascular health on the development and progression of AF. Social, genetic, and lifestyle risk factors have been shown to play a role in the racial paradox and AF outcomes in Black Americans. This review summarizes factors contributing to the racial paradox and discusses suggestions for improved health outcomes in Black Americans with AF.

Addressing racial differences in the management of atrial fibrillation: Focus on black patients

Atrial fibrillation (AF) is the most common sustained arrhythmia, affecting between 3 and 6 million people in the United States. It is associated with a reduced quality of life and increased risk of stroke, cognitive decline, heart failure and death. Black patients have a lower prevalence of AF than White patients but are more likely to suffer worse outcomes with the disease. It is important that stakeholders understand the disproportionate burden of disease and management gaps that exists among Black patients living with AF. Appropriate treatments, including aggressive risk factor control, early referral to cardiovascular specialists and improving healthcare access may bridge some of the gaps in management and improve outcomes.

Variations in the prevalence of atrial fibrillation, and in the strength of its association with ischemic stroke, in countries with different income levels: INTERSTROKE case-control study

BACKGROUND

The contribution of atrial fibrillation (AF) to the etiology and burden of stroke may vary by country income level.

AIMS

We examined differences in the prevalence of AF and described variations in the magnitude of the association between AF and ischemic stroke by country income level.

METHODS

In the INTERSTROKE case-control study, participants with acute first ischemic stroke were recruited across 32 countries. We included 10,363 ischemic stroke cases and 10,333 community or hospital controls who were matched for age, sex, and center. Participants were grouped into high-income (HIC), upper-middle-income (subdivided into two groups-UMIC-1 and UMIC-2), and lower-middle-income (LMIC) countries, based on gross national income. We evaluated the risk factors for AF overall and by country income level, and evaluated the association of AF with ischemic stroke.

RESULTS

AF was documented in 11.9% (n = 1235) of cases and 3.2% (n = 328) of controls. Compared to HIC, the prevalence of AF was significantly lower in UMIC-2 (aOR 0.35, 95% CI 0.29-0.41) and LMIC (aOR 0.50, 95% CI 0.41-0.60) on multivariable analysis. Hypertension, female sex, valvular heart disease, and alcohol intake were stronger risk factors for AF in lower-income countries, and obesity a stronger risk factor in higher-income countries. The magnitude of association between AF and ischemic stroke was significantly higher in lower-income countries compared to higher-income countries. The population attributable fraction for AF and stroke varied by region and was 15.7% (95% CI 13.7-17.8) in HIC, 14.6% (95% CI 12.3-17.1) in UMIC-1, 5.7% (95% CI 4.9-6.7) in UMIC-2, and 6.3% (95% CI 5.3-7.3) in LMIC.

CONCLUSION

Risk factors for AF vary by country income level. AF contributes to stroke burden to a greater extent in higher-income countries than in lower-income countries, due to a higher prevalence and despite a lower magnitude of odds ratio.

Relationship Between Radiation Exposure and Incident Atrial Fibrillation Among Atomic Bomb Survivors

Background: Atrial fibrillation (AF) is a common arrhythmia. Although radiation exposure is associated with an elevated risk of cardiovascular disease, the effects of radiation on arrhythmia, especially AF, are unclear. We evaluated the relationship between radiation and AF in a cohort of atomic bomb survivors. Methods and Results: From a baseline enrollment period (1967-1969) to 2009, 7,379 Hiroshima and Nagasaki atomic bomb survivors (mean baseline age 50.6 years, 65.8% women, 72.9% from Hiroshima) without AF and who had been exposed to estimated radiation doses between 0 and 3.614 Gy were followed-up once every 2 years. AF was identified by 12-lead electrocardiograms and medical records. Treating age as the time scale, AF incidence was modeled with Cox proportional hazards models adjusting for demographics, AF risk factors, and radiation. We modeled radiation as both a continuous variable and categorized according to radiation dose (Control [<0.005 Gy] and 5 equal-sized groups based on radiation dose quintiles in the cohort). Over 4 decades of follow-up, we identified 276 AF cases in 176,687 person-years, for an incidence rate of 1.56 per 1,000 person-years. After adjusting for sex and city, neither categorized, linear, nor linear-quadratic models showed substantive evidence of radiation effects. Similar results were obtained after adjusting for AF risk factors. Conclusions: There were no clear positive associations between radiation dose and AF risk, rather null or non-significant inverse associations.

Glycolysis Metabolites and Risk of Atrial Fibrillation and Heart Failure in the PREDIMED Trial

The increased prevalence of atrial fibrillation (AF) and heart failure (HF) highlights the need to better understand the mechanisms underlying these cardiovascular diseases (CVDs). In the present study, we aimed to evaluate the association between glycolysis-related metabolites and the risk of AF and HF in a Mediterranean population at high risk of CVD. We used two case-control studies nested within the PREDIMED trial. A total of 512 incident AF cases matched to 734 controls, and 334 incident HF cases matched to 508 controls, were included. Plasma metabolites were quantified by using hydrophilic interaction liquid chromatography coupled with high-resolution negative ion mode MS detection. Conditional logistic regression analyses were performed. The results showed no association between baseline plasma glycolysis intermediates and other related metabolites with AF. Only phosphoglycerate was associated with a higher risk of HF (OR _{for 1 SD increase}: 1.28; 95% CI: 1.06, 1.53). The present findings do not support a role of the glycolysis pathway in the pathogenesis of AF. However, the increased risk of HF associated with phosphoglycerate requires further studies.

Impact of Mobile Health Devices for the Detection of Atrial Fibrillation: Systematic Review

Background

Atrial fibrillation (AF) is the most common arrhythmia, and its prevalence is increasing. Early diagnosis is important to reduce the risk of stroke. Mobile health (mHealth) devices, such as single-lead electrocardiogram (ECG) devices, have been introduced to the worldwide consumer market over the past decade. Recent studies have assessed the usability of these devices for detection of AF, but it remains unclear if the use of mHealth devices leads to a higher AF detection rate.

Objective

The goal of the research was to conduct a systematic review of the diagnostic detection rate of AF by mHealth devices compared with traditional outpatient follow-up. Study participants were aged 16 years or older and had an increased risk for an arrhythmia and an indication for ECG follow-up—for instance, after catheter ablation or presentation to the emergency department with palpitations or (near) syncope. The intervention was the use of an mHealth device, defined as a novel device for the diagnosis of rhythm disturbances, either a handheld electronic device or a patch-like device worn on the patient’s chest. Control was standard (traditional) outpatient care, defined as follow-up via general practitioner or regular outpatient clinic visits with a standard 12-lead ECG or Holter monitoring. The main outcome measures were the odds ratio (OR) of AF detection rates.

Methods

Two reviewers screened the search results, extracted data, and performed a risk of bias assessment. A heterogeneity analysis was performed, forest plot made to summarize the results of the individual studies, and albatross plot made to allow the P values to be interpreted in the context of the study sample size.

Results

A total of 3384 articles were identified after a database search, and 14 studies with a 4617 study participants were selected. All studies but one showed a higher AF detection rate in the mHealth group compared with the control group (OR 1.00-35.71), with all RCTs showing statistically significant increases of AF detection (OR 1.54-19.16). Statistical heterogeneity between studies was considerable, with a Q of 34.1 and an I² of 61.9, and therefore it was decided to not pool the results into a meta-analysis.

Conclusions

Although the results of 13 of 14 studies support the effectiveness of mHealth interventions compared with standard care, study results could not be pooled due to considerable clinical and statistical heterogeneity. However, smartphone-connectable ECG devices provide patients with the ability to document a rhythm disturbance more easily than with standard care, which may increase empowerment and engagement with regard to their illness. Clinicians must beware of overdiagnosis of AF, as it is not yet clear when an mHealth-detected episode of AF must be deemed significant.

Angiotensin II and angiotensin 1-7: which is their role in atrial fibrillation?

Atrial fibrillation (AF) is a significant cause of morbidity and mortality as well as a public health burden considering the high costs of AF-related hospitalizations. Pre-clinical and clinical evidence showed a potential role of the renin angiotensin system (RAS) in the etiopathogenesis of AF. Among RAS mediators, angiotensin II (AII) and angiotensin 1-7 (A1-7) have been mostly investigated in AF. Specifically, the stimulation of the pathway mediated by AII or the inhibition of the pathway mediated by A1-7 may participate in inducing and sustaining AF. In this review, we summarize the evidence showing that both RAS pathways may balance the onset of AF through different biological mechanisms involving inflammation, epicardial adipose tissue (EAT) accumulation, and electrical cardiac remodeling. EAT is a predictor for AF as it may induce its onset through direct (infiltration of epicardial adipocytes into the underlying atrial myocardium) and indirect (release of inflammatory adipokines, the stimulation of oxidative stress, macrophage phenotype switching, and AF triggers) mechanisms. Classic RAS blockers such as angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) may prevent AF by affecting the accumulation of the EAT, representing a useful therapeutic strategy for preventing AF especially in patients with heart failure and known left ventricular dysfunction. Further studies are necessary to prove this benefit in patients with other cardiovascular diseases. Finally, the possibility of using the A1-7 or ACE2 analogues, to enlarge current therapeutic options for AF, may represent an important field of research.

Geographical variation and clustering are found in atrial fibrillation beyond socioeconomic differences: a Danish cohort study, 1987-2015

BACKGROUND

The prevalence and incidence rate of atrial fibrillation (AF) increase worldwide and AF is a risk factor for more adverse cardiovascular diseases including stroke. Approximately 44% of AF cases cannot be explained by common individual risk factors and risk might therefore also be related to the environment. By studying geographical variation and clustering in risk of incident AF adjusted for socioeconomic position at an individual level, potential neighbourhood risk factors could be revealed.

METHODS

Initially, yearly AF incidence rates 1987-2015 were estimated overall and stratified by income in a register-based cohort study. To examine geographical variation and clustering in AF, we used both spatial scan statistics and a hierarchical Bayesian Poisson regression analysis of AF incidence rates with random effect of municipalities (n = 98) in Denmark in 2011-2015.

RESULTS

The 1987-2015 cohort included 5,453,639 individuals whereof 369,800 were diagnosed with an incident AF. AF incidence rate increased from 174 to 576 per 100,000 person-years from 1987 to 2015. Inequality in AF incidence rate ratio between highest and lowest income groups increased from 23% in 1987 to 38% in 2015. We found clustering and geographical variation in AF incidence rates, with incidence rates at municipality level being up to 34% higher than the country mean after adjusting for socioeconomic position.

CONCLUSIONS

Geographical variations and clustering in AF incidence rates exist. Compared to previous studies from Alberta, Canada and the United States, we show that geographical variations exist in a country with free access to healthcare and even when accounting for socioeconomic differences at an individual level. An increasing social inequality in AF was seen from 1987 to 2015. Therefore, when planning prevention strategies, attention to individuals with low income should be given. Further studies focusing on identification of neighbourhood risk factors for AF are needed.

Comparison of Frequency of Atrial Fibrillation in Blacks Versus Whites and the Utilization of Race in a Novel Risk Score

Blacks have a lower prevalence of atrial fibrillation (AF) compared with Whites. We sought to confirm previously reported ethnic trends in AF in Blacks and Whites in a large database, and develop a prediction score for AF. Over 330 million hospital discharges between the years 2003 to 2013 from the National Inpatient Sample database were analyzed. All hospitalizations with a diagnosis of AF formed the study cohort. Traditional risk factors for the development of AF were compared between Blacks and Whites. Univariate and multiple logistic regression analyses were used to formulate a risk score to predict AF-CHADSAVES (Congestive heart failure, Hypertension, Age>65 years, Diabetes Mellitus, prior Stroke, Age>75 years, Vascular disease, White Ethnicity, and previous cardiothoracic Surgery). AF prevalence in Whites was 11.3% vs 4.6% in Blacks (p < 0.001). Blacks were younger (33.8% vs 14.4% patients <65 years, p < 0.01) and had less males (46.3% vs 49.4%, p < 0.01). Blacks had more hypertension (71.3% vs 64.1%, p < 0.01), congestive heart failure (24.8% vs 22.6%, p < 0.01), diabetes mellitus with (7.5% vs 4.7%, p < 0.01) or without complications (30.3% vs 23.1%, p < 0.01), renal failure (29.7% vs 17.1%, p < 0.01), and obesity (13.1% vs 8.7%, p < 0.01). CHADSAVES predicted AF in the study population (NIS 2003 to 2013) with an AUC of 0.82 and verified in a validation cohort (NIS 2014) with an AUC of 0.85. In conclusion, our data confirm a significant AF ethnicity paradox. Despite a higher prevalence of traditional risk factors for AF, Blacks had >2-fold lower prevalence of AF compared with Whites. CHADSAVES can be used effectively to predict AF in inpatients.

High Plasma Glutamate and a Low Glutamine-to-Glutamate Ratio Are Associated with Increased Risk of Heart Failure but Not Atrial Fibrillation in the Prevención con Dieta Mediterránea (PREDIMED) Study

BACKGROUND

Although the association between glutamate and glutamine in relation to cardiometabolic disorders has been evaluated, the role of these metabolites in the development of atrial fibrillation (AF) and heart failure (HF) remains unknown.

OBJECTIVES

We examined associations of glutamate, glutamine, and the glutamine-to-glutamate ratio with AF and HF incidence in a Mediterranean population at high cardiovascular disease (CVD) risk.

METHODS

The present study used 2 nested case-control studies within the PREDIMED (Prevención con Dieta Mediterránea) study. During ∼10 y of follow-up, there were 509 AF incident cases matched to 618 controls and 326 HF incident cases matched to 426 controls. Plasma concentrations of glutamate and glutamine were semiquantitatively profiled with LC-tandem MS. ORs were estimated with multivariable conditional logistic regression models.

RESULTS

In fully adjusted models, per 1-SD increment, glutamate was associated with a 29% (95% CI: 1.08, 1.54) increased risk of HF and glutamine-to-glutamate ratio with a 20% (95% CI: 0.67, 0.94) decreased risk. Glutamine-to-glutamate ratio was also inversely associated with HF risk (OR per 1-SD increment: 0.80; 95% CI: 0.67, 0.94) when comparing extreme quartiles. Higher glutamate concentrations were associated with a worse cardiometabolic risk profile, whereas a higher glutamine-to-glutamate ratio was associated with a better cardiometabolic risk profile. No associations between the concentrations of these metabolites and AF were observed.

CONCLUSIONS

Our findings suggest that high plasma glutamate concentrations possibly resulting from alterations in the glutamate-glutamine cycle may contribute to the development of HF in Mediterranean individuals at high CVD risk.This trial was registered at www.isrctn.com as ISRCTN35739639.

Environmental factors, serum biomarkers and risk of atrial fibrillation: an exposure-wide umbrella review of meta-analyses

Atrial fibrillation (AF) is the most common cardiac arrhythmia. We designed an umbrella review to systematically assess the epidemiological credibility of the associations of non-genetic factors with risk of AF. We searched PubMed and EMBASE from inception to December 31, 2018 to identify systematic reviews and meta-analyses of observational studies for the association of non-genetic factors with risk of AF. For each meta-analysis, we used the random-effects model, and we estimated the 95% confidence and prediction intervals. We also assessed between-study heterogeneity, small-study effects and excess significance bias. We identified 34 eligible papers that examined 51 associations of 42 unique non-genetic factors with risk of AF. Eighteen associations remained statistically significant at P value < 1 × 10-6. Thirty-one associations presented large or very large between-study heterogeneity. Eight associations presented evidence for small-study effects and 13 associations had evidence for excess significance bias. Ten associations, i.e. corrected QT interval, alcohol consumption (highest vs. lowest category, per 1 drink/day increase), body mass index (> 30 units vs. < 30 units, per 5 units increase), waist circumference, body weight, type 2 diabetes mellitus, and smoking (ever vs. never, per 10 cigarettes/day increase) were supported by convincing or highly suggestive evidence in meta-analyses of prospective cohort studies. Type 2 diabetes mellitus, markers of adiposity, alcohol consumption, smoking, and corrected QT interval constitute credible risk factors of AF. Our proposed grading may guide the design of future studies, including Mendelian randomization studies, to assess whether these associations are causal.

Parental Atrial Fibrillation and Stroke or Atrial Fibrillation in Young Adults

Background and Purpose- Cryptogenic strokes are often the first clinical manifestation of undiagnosed atrial fibrillation (AF). We designed this study to test whether parental AF is a risk factor for stroke in young adults. Methods- Population-based cohort study using linked administrative databases from April 1, 1972 to March 31, 2016 in Manitoba, Canada for 325 333 offspring (age ≥18 years) with at least 1 linked parent (total 582 195 parents). We examined the association between parental history of AF and stroke or transient ischemic attack (TIA) in the offspring using multivariable Cox proportional hazards models. Results- Offspring median age at study entry was 18 years. During 5.533 million person-years of follow-up (mean 17 years), 8678 offspring had an incident stroke or TIA (5.2% of the 24 583 offspring with a parental history of AF compared with 2.5% of the 300 750 offspring with no parental history of AF), and 1430 were diagnosed with AF (1.9% versus 0.3%). Incidence rates for stroke/TIA were higher in offspring with a parental history of AF (195.0 versus 156.6 per 100 000 person-years). Parental AF was associated with elevated risk in offspring of stroke/TIA (hazard ratio 1.11; 95% CI, 1.04-1.18) or AF (hazard ratio 1.75; 95% CI, 1.55-1.97) and a higher frequency of other cardiovascular risk factors. After adjusting for demographics, region of residence, socioeconomic status, and other stroke risk factors in offspring, parental AF was associated with AF in their offspring in young adulthood (adjusted hazard ratio 1.61; 95% CI, 1.43-1.82); the association of parental AF with offspring stroke/TIA was attenuated (adjusted hazard ratio 1.05; 95% CI, 0.99-1.12) after adjusting for the other cardiovascular risk factors. Conclusions- Parental AF is associated with increased risk of AF and other cardiovascular risk factors in their offspring during early adulthood, resulting in increased stroke risk.

Transmitral inflow wave and progression from paroxysmal to permanent atrial fibrillation in Asian people

Objective

Paroxysmal atrial fibrillation could progress to permanent atrial fibrillation. Whether the transmitral inflow waves could be used to predict progression from paroxysmal atrial fibrillation to permanent atrial fibrillation is unknown. Therefore, we investigated the association between the transmitral inflow waves and progression of paroxysmal atrial fibrillation.

Method

We performed a retrospective study by analysing clinical and echocardiographic data from 88 patients with paroxysmal atrial fibrillation. We excluded patients who had structural heart disease, significant valvular disease, cardiomyopathy, cardiac device implantation or a left ventricular ejection fraction <50%.

Result

The patients with progression to permanent atrial fibrillation were more likely to be male and had lower peak A velocity than those without progression. After adjusting for covariates, lower peak A velocity remained the independent predictor of progression to permanent atrial fibrillation (p=0.025).

Conclusion

The A velocity could be useful for predicting progression to permanent atrial fibrillation in Asian people.

Uric acid: from a biological advantage to a potential danger. A focus on cardiovascular effects

Non-communicable diseases represent nowadays the most common cause of death worldwide, having largely overcome infectious diseases. Among them, cardiovascular diseases constitute the majority. Given these premise, great efforts have been made by scientific societies to emphasize the fundamental role of cardiovascular prevention and risk factors control. In addition to classical cardiovascular risk factors such as smoking, arterial hypertension, hypercholesterolemia and male gender, new risk factors are emerging from international literature. Among them, uric acid is the protagonist. Several evidences show a direct role of hyperuricemia in the determinism of metabolic and vascular disorders. From the other hand, some researchers have demonstrated that uric acid is only a marker of cardiovascular damage and not a risk factor for its development. Aim of this review is to evaluate the scientific evidences on the role of uric acid in cardiovascular diseases in order to shed light on this confusing topic.

Sex as a biological variable in the pathology and pharmacology of neurodegenerative and neurovascular diseases

The incidence of dementia, most commonly caused by cerebrovascular and neurodegenerative diseases, continues to grow as our population ages. Alzheimer disease (AD) and vascular cognitive impairment (VCI) are responsible for more than 80% of all cases of dementia. There are few effective, long-term treatments for AD and VCI-related conditions (e.g., stroke and cerebral amyloid angiopathy (CAA)). This review focuses on AD (as the most common "neurodegenerative" cause of dementia), CAA (as an "emerging" cause of dementia), and stroke (as the most common cause of "vascular" dementia). We will discuss the available literature on the pharmacological therapies that demonstrate sex differences, which refer to any combination of structural, chromosomal, gonadal, or hormonal differences between males and females. We will emphasize the importance of considering sex as a biological variable in the design of preclinical and clinical studies that investigate underlying pathologies or response to pharmacological interventions in dementia. LINKED ARTICLES: This article is part of a themed section on The Importance of Sex Differences in Pharmacology Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.21/issuetoc.

Evaluation of a clinical score for predicting atrial fibrillation in cryptogenic stroke patients with insertable cardiac monitors: results from the CRYSTAL AF study

Background

The HAVOC score was previously developed to predict the risk of atrial fibrillation (AF) after cryptogenic stroke (CS) or transient ischemic attack (TIA). The purpose of this study was to apply the HAVOC score to patients who received insertable cardiac monitors (ICMs) in the CRYSTAL AF study.

Methods

All patients from the CRYSTAL AF study who received an ICM were included. HAVOC score (one point each for peripheral vascular disease and obesity with body mass index >30, two points each for hypertension, age ⩾ 75, valvular heart disease, and coronary artery disease, 4 points for congestive heart failure) was computed for all patients. The primary endpoint was AF detection by 12 months of ICM monitoring.

Results

A total of 214 patients who received ICM were included. AF was detected in 40 patients while the remaining 174 patients were AF negative. The HAVOC score was significantly higher among patients with AF [median 3.0 with interquartile range (IQR) 2-4] than those without AF [median 2.0 (IQR 0-3)], p = 0.01. AF increased significantly across the three HAVOC score groups: 11% in Group A (score 0-1), 18% in Group B (score 2-3), and 32 % in Group C (score ⩾ 4) with p = 0.02.

Conclusions

The HAVOC score was shown in this post hoc analysis of CRYSTAL AF to successfully stratify AF risk post CS or TIA. The 11% AF rate in the lowest HAVOC score group highlights the significance of nontraditional contributors to AF and ischemic stroke.

Heart failure with reduced ejection fraction: comparison of patient characteristics and clinical outcomes within Asia and between Asia, Europe and the Americas

Aims

Nearly 60% of the world's population lives in Asia but little is known about the characteristics and outcomes of Asian patients with heart failure with reduced ejection fraction (HFrEF) compared to other areas of the world.

Methods and results

We pooled two, large, global trials, with similar design, in 13 174 patients with HFrEF (patient distribution: China 833, India 1390, Japan 209, Korea 223, Philippines 223, Taiwan 199 and Thailand 95, Western Europe 3521, Eastern Europe 4758, North America 613, and Latin America 1110). Asian patients were younger (55.0–63.9 years) than in Western Europe (67.9 years) and North America (66.6 years). Diuretics and devices were used less, and digoxin used more, in Asia. Mineralocorticoid receptor antagonist use was higher in China (66.3%), the Philippines (64.1%) and Latin America (62.8%) compared to Europe and North America (range 32.8% to 49.6%). The rate of cardiovascular death/heart failure hospitalization was higher in Asia (e.g. Taiwan 17.2, China 14.9 per 100 patient‐years) than in Western Europe (10.4) and North America (12.8). However, the adjusted risk of cardiovascular death was higher in many Asian countries than in Western Europe (except Japan) and the risk of heart failure hospitalization was lower in India and in the Philippines than in Western Europe, but significantly higher in China, Japan, and Taiwan.

Conclusion

Patient characteristics and outcomes vary between Asia and other regions and between Asian countries. These variations may reflect several factors, including geography, climate and environment, diet and lifestyle, health care systems, genetics and socioeconomic influences.

Racial and ethnic differences in the prevalence, management, and outcomes in patients with atrial fibrillation: A systematic review

Atrial fibrillation (AF) is the most common cardiac arrhythmia in the United States and is associated with increased morbidity, mortality, and health care expenditures. In this review, our aim was to assess the racial and ethnic differences in the epidemiology, management, and outcomes of patients with AF. A search of relevant studies from January 1, 2007, to December 30, 2017, was conducted in PubMed, EMBASE, and Web of Science and supplemented by manual searches of the bibliographies of retrieved articles. We identified 152 studies of which 64 were subsequently included. We found that underrepresented racial and ethnic groups have a higher prevalence of established risk factors associated with the development of AF but an overall lower incidence and prevalence of AF as compared with non-Hispanic whites. Moreover, racial and ethnic differences exist in detection, awareness, and AF-associated symptoms. Nonwhite populations also experience decreased use of rhythm control modalities and anticoagulation for stroke prevention. Lastly, among those with AF, underrepresented racial and ethnic groups had increased morbidity and mortality relative to white groups. Racial and ethnic differences exist in the prevalence, quality of life, management, and outcomes of individuals with AF; however, the mechanisms for these differences have yet to be fully elucidated. Racial and ethnic differences in AF warrant further analysis to understand the factors contributing to the differences in prevalence and management to ensure the delivery of high quality care that prevents stroke, reduces deaths, and decreases expenses associated with caring for underrepresented populations with AF.

Plasma Concentrations and Dietary Intakes of Choline and Betaine in Association With Atrial Fibrillation Risk: Results From 3 Prospective Cohorts With Different Health Profiles

Background

Although choline metabolism has been associated with atherosclerotic heart disease, less research attention has been paid to the associations of choline and its oxidative metabolite betaine with cardiac arrhythmias.

Methods and Results

We evaluated associations of plasma concentrations and dietary intakes of choline and betaine with long‐term atrial fibrillation (AF) risk in a community‐based cohort, HUSK ([the Hordaland Health Study] n=6949), and validated the findings in 2 patient cohorts: the Western Norway Coronary Angiography Cohort (n=4164) and the NORVIT (Norwegian B‐Vitamin) Trial (n=3733). Information on AF was obtained from the CVDNOR (Cardiovascular Disease in Norway) project. In HUSK, WECAC (Western Norway Coronary Angiography Cohort), and NORVIT, 552, 411, and 663 AF cases were identified during a median follow‐up time of 10.9, 7.3, and, 8.7 years, respectively. Plasma concentrations of choline and betaine were significantly positively associated with later AF risk after multivariable adjustments in HUSK. Such associations were independently replicated in the 2 external prospective patient cohorts. The pooled hazard ratio was 1.13 (95% confidence interval 1.08‐1.19, P<0.001) and 1.16 (95% confidence interval 1.10‐1.22, P<0.001) per SD increment for log‐transformed choline and betaine, respectively. Moreover, dietary intake of choline was marginally associated with AF risk (pooled hazard ratio 1.29, 95% confidence interval 1.01‐1.66, fifth versus first quintile), whereas no significant association was observed between dietary betaine and AF risk.

Conclusions

Our findings indicate that plasma concentrations as well as dietary intake of choline, but not betaine, are associated with subsequent risk of AF, suggesting a potential role of choline metabolism in the pathogenesis of AF.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov.Unique identifier: NCT00671346.

Cardiovascular outcomes in diabetic kidney disease: insights from recent clinical trials

The prevalence of type 2 diabetes is catalyzing a pandemic in kidney disease, with ensuing cardiovascular complications. The effort to identify antidiabetic agents capable of promoting benefits that go beyond the bounds of glucose control has produced remarkable outcomes in recent cardiovascular outcomes trials in patients with type 2 diabetes mellitus, many of whom have diabetic kidney disease. Two novel antidiabetic drug classes, sodium-glucose cotransporter 2 inhibitors (SGLT2is) and glucagon-like peptide-1 receptor agonists (GLP-1 RAs), improve cardiovascular outcomes in different ways, with SGLT2is reducing the risk of heart failure and cardiovascular death and GLP-1 RAs being associated with reduced risk of myocardial infarction and cardiovascular death. Further mechanistic studies and additional cardiovascular outcome trials are ongoing and are expected to determine whether these benefits are a result of class effect, as well as to delineate optimum timing for intervention and population target.

Serum uric acid and atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) represents a significant health concern, due to the increased prevalence, morbidity, and mortality.

METHODS AND RESULTS

There is a growing body of evidence correlating serum uric acid (SUA) with cardiovascular diseases such as arterial hypertension and AF.

CONCLUSION

Thus, a question arises as to whether SUA levels have a role in the pathophysiology of AF development.

Atrial ectopy and N-terminal pro-B-type natriuretic peptide as predictors of atrial fibrillation: a population-based cohort study

Aims

The risk of incident atrial fibrillation (AF) can be estimated by clinical parameters in the Framingham AF risk model. Elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) and increased rate of premature atrial contractions (PACs) have been shown to be associated with AF, but the additive value of both of these biomarkers in the Framingham AF risk model has not been fully examined.

Methods and results

A total of 646 subjects from the Copenhagen Holter Study (mean age 64.4 ± 6.8 years, 41.6% women) with no history of prior AF, stroke or cardiovascular disease were followed for the diagnosis of incident AF or death (median follow-up time 14.4 years). Median NT-proBNP was 6.7 pmol/L (IQR: 3.6-13.5), median PAC count was 1.4 beats/h (IQR: 0.6-4.5), 71 (11.0%) subjects developed AF, and 244 (37.8%) died. Multiple Cox regression including Framingham AF risk score, log-transformed NT-proBNP, and log-transformed PAC showed a significant increase in AF hazard risk [hazard ratio (HR) 1.45, 95% confidence interval (CI) 1.14-1.85, P = 0.002; HR 1.23, 95% CI 1.09-1.39, P = 0.001]. The addition of PAC to the Framingham AF risk model significantly improved the time-dependent area under the receiver operating characteristic curve (AUC 65.6 vs. 72.6; P = 0.008), while the addition of NT-proBNP did not.

Conclusion

Atrial fibrillation risk discrimination was significantly improved by the addition of PAC to the Framingham AF risk model, but not by the addition of NT-proBNP.

Incidence and risk factors of atrial fibrillation in Asian COPD patients

Objective

To investigate the incidence and risk factors of atrial fibrillation (AF) in Asian chronic obstructive pulmonary disease (COPD) patients.

Patients and methods

We selected a study population older than 40 years with a COPD diagnosis and who had used at least one inhaled bronchodilator medication between 1998 and 2012. The date of the index COPD diagnosis was defined as the index date. We excluded patients with a history of AF, significant mitral valve disease, disorders of the thyroid gland, or ischemic heart disease before the index date. We followed all patients from the index date to the day of AF occurrence, the day of death, or the date of December 31, 2013. The baseline of comorbidities was identified before the index date. Comorbidities included hypertension, diabetes mellitus, end-stage renal disease, congenital heart failure, stroke, peripheral arterial occlusive disease, and malignancy.

Results

We included 6,208 COPD patients and 12,409 patients without COPD. The incidence of AF was higher in COPD patients than in those without COPD. The adjusted hazard ratio (HR) for AF among those with COPD was 2.23 with a 95% confidence interval (CI) of 1.98–2.51 compared to those without COPD. After multiple analyses, patients with hypertension (HR 1.43 [95% CI =1.26–1.62]) or heart failure (HR 2.36 [95% CI =1.81–3.08]) were found to have a significantly higher incidence of AF than those without these conditions.

Conclusion

It is important for physicians to monitor, prevent, and provide early intervention for AF in COPD patients with hypertension or heart failure.

High-Sensitivity Troponin as a Biomarker in Heart Rhythm Disease

Biomarkers are important prognostic tools in various cardiovascular conditions, including coronary artery disease and heart failure. Although their utility in cardiac electrophysiology (EP) is less established, biomarkers may guide EP clinical practice by identifying patients at risk for developing arrhythmias and their complications, in addition to augmenting therapeutic decisions by targeting appropriate pharmacologic and interventional therapies to patients who may benefit most. In this review, we focus on the prognostic role of high-sensitivity cardiac troponin (hs-cTn) assays-which detect subclinical cardiac myocyte damage-in cardiac arrhythmias and their sequelae. We review the current literature on hs-cTn and its impact on various arrhythmia disease states and also provide suggestions for future research in this field. In conclusion, although the utility of hs-cTn assays remains at an investigational stage in cardiac EP, studies to date have suggested value as a prognostic biomarker in atrial fibrillation and as a screening marker for patients at high risk of sudden cardiac death (both in the general population and among those with hypertrophic cardiomyopathy).

Application of Biomarkers for Risk Stratification in Patients with Atrial Fibrillation

BACKGROUND

Atrial fibrillation is the most common sustained arrhythmia and an important contributor to cardiovascular morbidity and mortality. Several strategies have been proposed for prediction of outcomes and individualization of treatments to better balance the benefits of stroke prevention and risks of bleeding during anticoagulation.

CONTENT

The availability of analytically more specific and sensitive methods to measure circulating biomarkers of cellular and organ stress and dysfunction has led to testing of their utility in several cardiovascular conditions. In patients with atrial fibrillation, biomarkers of myocardial injury (troponin) and cardiovascular stress and dysfunction (natriuretic peptides, growth differentiation factor 15), myocardial fibrosis (galectin-3), renal dysfunction (creatinine, cystatin C), inflammation (C-reactive protein, cytokines) and coagulation activity (d-dimer) have been found associated with underlying pathophysiology, clinical outcomes and effects of treatment. Measurements of these markers might therefore expand the understanding of the pathophysiology, improve risk assessment and optimize treatment in individual patients with atrial fibrillation.

SUMMARY

Biomarkers for risk stratification have potential roles as tools for evaluation of patients with atrial fibrillation and for selection of the best treatment strategies to prevent stroke, major bleeding, and mortality.

The risk of atrial fibrillation in patients with gout: a nationwide population-based study

Many studies have found that systemic inflammation plays an important role in the pathogenesis of atrial fibrillation (AF). Gout is a chronic systemic inflammatory disorder, but little evidence exists regarding whether the risk of AF is increased in patients with gout. The National Health Insurance Research Database in Taiwan was used in this study, and gout was defined as the occurrence of at least one episode of an acute gout attack requiring medical treatment. A total of 63264 gout and 63264 age- and gender-matched patients were included as the study population. The Cox model was used to evaluate the risk of AF in patients with gout. Patients with gout experienced a greater frequency of co-morbidities compared to patients without gout. The cumulative incidences of AF were 4.61% and 3.04% in patients with and without gout, respectively (log-rank test, P < 0.001). After adjusting for co-morbidities and prescription medication use, gout was found to be associated with AF [hazard ratio (HR), 1.38]. Moreover, the HR for AF decreased with increasing age in our study. Gout was found to be associated with an increased risk of developing AF after adjusting for potential confounders.

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.

Metabolomics and Incidence of Atrial Fibrillation in African Americans: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Atrial fibrillation (AF) is a common arrhythmia. Application of metabolomic approaches, which may identify novel pathways and biomarkers of disease risk, to a longitudinal epidemiologic study of AF has been limited.

METHODS

We determined the prospective association of 118 serum metabolites identified through untargeted metabolomics profiling with the incidence of newly-diagnosed AF in 1919 African-American men and women from the Atherosclerosis Risk in Communities study without AF at baseline (1987-1989). Incident AF cases through 2011 were ascertained from study electrocardiograms, hospital discharge codes, and death certificates.

RESULTS

During a median follow-up of 22 years, we identified 183 incident AF cases. In Cox proportional hazards models adjusted for age, sex, smoking, body mass index, systolic blood pressure, use of antihypertensive medication, diabetes, prevalent heart failure, prevalent coronary heart disease, and kidney function, two conjugated bile acids (glycolithocholate sulfate and glycocholenate sulfate) were significantly associated with AF risk after correcting for multiple comparisons (p<0.0004). Multivariable-adjusted hazard ratios (95% confidence intervals) of AF were 1.22 (1.12-1.32) for glycolithocholate sulfate and 1.22 (1.10-1.35) for glycocholenate sulfate per 1-standard deviation higher levels. Associations were not appreciably different after additional adjustment for alcohol consumption or concentrations of circulating albumin and liver enzymes.

CONCLUSION

We found an association of higher levels of two bile acids with an increased risk of AF, pointing to a potential novel pathway in AF pathogenesis. Replication of results in independent studies is warranted.

Coronary atherosclerosis and adverse outcomes in patients with recent-onset atrial fibrillation and troponin rise

BACKGROUND

The relationship between troponin and atrial fibrillation (AF) without acute coronary syndrome is still unclear. We sought to investigate the presence of coronary atherosclerosis and adverse outcomes in patients with AF.

METHODS

Consecutive patients with recent-onset AF and without severe comorbidities were enrolled between 2004 and 2013. Patients with a troponin rise or with adverse outcomes were considered for coronary angiography and revascularization when "critical" stenosis (≥70%) was recognized. Propensity score matching was performed to adjust for baseline characteristics; after matching, no differences existed between the groups of patients with or without troponin rise. The primary end point was the composite of acute coronary syndrome, revascularization, and cardiac death at 1- and 12-month follow-ups.

RESULTS

Of 3627 patients enrolled, 3541 completed the study; 202 (6%) showed troponin rise; and 91 (3%), an adverse outcome. In the entire cohort, on multivariate analysis, the odds ratio for the occurrence of the primary end point of troponin rise was 14 (95% confidence interval [CI], 10-23; P<.001), and that of known coronary artery disease was 3 (CI, 2-5; P=.001). In the matching cohort, the odds ratio of troponin rise was 10 (CI, 4-22; P<.001), and that of TIMI score greater than 2 was 4 (CI, 2-9; P≤.001). In the entire cohort, patients with or without troponin rise achieved the primary end point in 38 (19%) and 43 (1%) patients, respectively (P<.001). Stroke occurred in 4 (2%) and 20 (1%), respectively (P=.018). Critical stenosis and revascularization account for 23 (12%) and 15 (1%), respectively (P<.001). In the matching cohort, results were confirmed, but incidence of stroke was comparable.

CONCLUSIONS

Patients with recent-onset AF and troponin rise showed higher prevalence of coronary atherosclerosis and adverse cardiac events. Stroke per se did not succeed in justifying the high morbidity. Thus, beyond stroke, coronary atherosclerosis might have a pivotal role in poor outcomes.

Global epidemiology of atrial fibrillation

Atrial fibrillation (AF) is a major public health burden worldwide, and its prevalence is set to increase owing to widespread population ageing, especially in rapidly developing countries such as Brazil, China, India, and Indonesia. Despite the availability of epidemiological data on the prevalence of AF in North America and Western Europe, corresponding data are limited in Africa, Asia, and South America. Moreover, other observations suggest that the prevalence of AF might be underestimated-not only in low-income and middle-income countries, but also in their high-income counterparts. Future studies are required to provide precise estimations of the global AF burden, identify important risk factors in various regions worldwide, and take into consideration regional and ethnic variations in AF. Furthermore, in response to the increasing prevalence of AF, additional resources will need to be allocated globally for prevention and treatment of AF and its associated complications. In this Review, we discuss the available data on the global prevalence, risk factors, management, financial costs, and clinical burden of AF, and highlight the current worldwide inadequacy of its treatment.

Plasma NT-proBNP as predictor of change in functional status, cardiovascular morbidity and mortality in the oldest old: the Leiden 85-plus study

In the aging society, it is important to identify very old persons at high risk of functional decline, cardiovascular disease and mortality. However, traditional risk markers lose their predictive value with age. We investigated whether plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels predict change in functional status, cardiovascular morbidity and mortality in very old age. Here we present an observational prospective cohort study (Leiden 85-plus Study, 1997-2004) in a population-based sample of 560 individuals aged 85 years with a 5-year complete follow-up for functional status, cardiovascular morbidity and cause-specific mortality. Median NT-proBNP for men was 351 pg/ml (cutoff values for low-medium tertiles 201 pg/ml and medium-high tertiles 649 pg/ml) and, for women, 297 pg/ml (cutoffs 204 and 519 pg/ml, respectively). During the 5-year follow-up, participants with high NT-proBNP had an accelerated cognitive decline and increase of activities of daily living (ADL) disability over time (all at p < 0.01) and an increased risk of incident heart failure [hazard ratio (HR) 3.3 (95 % confidence interval (CI) 1.8-6.1)], atrial fibrillation [HR 4.1 (2.0-8.7)], myocardial infarction [HR 2.1 (1.2-3.7)], stroke [HR 3.4 (1.9-6.3)], cardiovascular mortality [HR 5.5 (3.1-10)], non-cardiovascular mortality [HR 2.0 (1.4-3.0)] and all-cause mortality [HR 2.9 (2.1-4.0)], independent of other known risk markers. All results remained similar after exclusion of participants with heart failure at baseline. In very old age, high-NT-proBNP levels predict accelerated cognitive and functional decline, as well as cardiovascular morbidity and mortality. Results suggest that NT-proBNP can help clinicians to identify very old people at high risk of functional impairment and incident cardiovascular morbidity.

Lone atrial fibrillation - an overview

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

Monoamine oxidase is a major determinant of redox balance in human atrial myocardium and is associated with postoperative atrial fibrillation

Background

Onset of postoperative atrial fibrillation (POAF) is a common and costly complication of heart surgery despite major improvements in surgical technique and quality of patient care. The etiology of POAF, and the ability of clinicians to identify and therapeutically target high‐risk patients, remains elusive.

Methods and Results

Myocardial tissue dissected from right atrial appendage (RAA) was obtained from 244 patients undergoing cardiac surgery. Reactive oxygen species (ROS) generation from multiple sources was assessed in this tissue, along with total glutathione (GSHt) and its related enzymes GSH‐peroxidase (GPx) and GSH‐reductase (GR). Monoamine oxidase (MAO) and NADPH oxidase were observed to generate ROS at rates 10‐fold greater than intact, coupled mitochondria. POAF risk was significantly associated with MAO activity (Quartile 1 [Q1]: adjusted relative risk [ARR]=1.0; Q2: ARR=1.8, 95% confidence interval [CI]=0.84 to 4.0; Q3: ARR=2.1, 95% CI=0.99 to 4.3; Q4: ARR=3.8, 95% CI=1.9 to 7.5; adjusted P_trend=0.009). In contrast, myocardial GSHt was inversely associated with POAF (Quartile 1 [Q1]: adjusted relative risk [ARR]=1.0; Q2: ARR=0.93, 95% confidence interval [CI]=0.60 to 1.4; Q3: ARR=0.62, 95% CI=0.36 to 1.1; Q4: ARR=0.56, 95% CI=0.34 to 0.93; adjusted P_trend=0.014). GPx also was significantly associated with POAF; however, a linear trend for risk was not observed across increasing levels of the enzyme. GR was not associated with POAF risk.

Conclusions

Our results show that MAO is an important determinant of redox balance in human atrial myocardium, and that this enzyme, in addition to GSHt and GPx, is associated with an increased risk for POAF. Further investigation is needed to validate MAO as a predictive biomarker for POAF, and to explore this enzyme's potential role in arrhythmogenesis.

[Relationship between antihypertensive drug use and development of atrial fibrillation in hypertensive patients in a Primary Care center]

INTRODUCTION

Although antihypertensive treatment can reduce the risk of cardiovascular morbimortality, studies aimed at evaluating the association between antihypertensive drug use and incidence of atrial fibrillation (AF) yield mixed results. This study aimed to determine the possible relationship between antihypertensive drug use and development of AF.

MATERIAL AND METHODS

Case control study.

CASES

Hypertensive patients with AF diagnosed at least one year after the start of drug treatment for hypertension.

CONTROLS

Hypertensive patients without AF with pharmacological antihypertensive treatment for at least one year, matching by sex, age and duration of antihypertensive therapy at diagnosis of AF cases. The study included 136 cases and 132 controls.

VARIABLES

AF, antihypertensive drugs, control of hypertension, duration of treatment with antihypertensive drugs, number of antihypertensive drugs.

ANALYSIS

Crude OR were calculated, with logistic regression being used to calculate the adjusted odds ratios.

RESULTS

Overall, diuretics was close to statistical significance: OR 0.616 (95% CI 0.365 to 1.040), as a protective factor for development of AF. Calcium channel blockers behaved as a protective factor against development of AF at 75 years or older (OR 0.366; 95% CI 0.173 to 0.772), and within this age in women (OR 0.343; 95% CI 0.145-0.811).

CONCLUSIONS

Calcium channel blockers in the group of 75 years or more, especially in women, worked statistically significant as a drug protecting against the appearance of AF. Diuretics may have a protective role in AF incidence in all hypertensive patients.

Relation between soluble ST2, growth differentiation factor-15, and high-sensitivity troponin I and incident atrial fibrillation

BACKGROUND

We investigated whether circulating concentrations of soluble ST2, growth differentiation factor-15 (GDF-15), and high-sensitivity troponin I (hsTnI) are associated with incident atrial fibrillation (AF) and whether these biomarkers improve current risk prediction models including AF risk factors, B-type natriuretic peptide (BNP), and C-reactive protein (CRP).

METHODS

We studied the relation between soluble ST2, GDF-15, and hsTnI and development of AF in Framingham Heart Study participants without prevalent AF. We used Cox proportional hazard regression analysis to examine the relation of incident AF during a 10-year follow-up period with each biomarker. We adjusted for standard AF clinical risk factors, BNP, and CRP.

RESULTS

The mean age of the 3,217 participants was 59 ± 10 years, and 54% were women. During a 10-year follow-up, 242 participants developed AF. In age- and sex-adjusted models, GDF-15 and hsTnI were associated with risk of incident AF; however, after including the AF risk factors and BNP and CRP, only hsTnI was significantly associated with AF (hazard ratio per 1 SD of loge hsTnI, 1.12, 95% CI 1.00-1.26, P = .045). The c statistic of the base model including AF risk factors, BNP, and CRP was 0.803 (95% CI 0.777-0.830) and did not improve by adding individual or all 3 biomarkers. None of the discrimination and reclassification statistics were significant compared with the base model.

CONCLUSION

In a community-based cohort, circulating hsTnI concentrations were associated with incident AF. None of the novel biomarkers evaluated improved AF risk discrimination or reclassification beyond standard clinical AF risk factors and biomarkers.

Genetic variation in the β1-adrenergic receptor is associated with the risk of atrial fibrillation after cardiac surgery

BACKGROUND

Postoperative atrial fibrillation (PoAF) after cardiac surgery is common and associated with increased morbidity and mortality. Increased sympathetic activation after surgery contributes to PoAF, and β-blockers are the first-line recommendation for its prevention. We examined the hypothesis that common functional genetic variants in the β1-adrenoreceptor, the mediator of cardiac sympathetic activation and drug target of β-blockers, are associated with the risk for PoAF and with the protective effect of β-blockers.

METHODS

In a prospective cohort study, we studied 947 adult European Americans who underwent cardiac surgery at Vanderbilt University between 1999 and 2005. We genotyped 2 variants in the β1-adrenoreceptor, rs1801253 (Arg389Gly) and rs1801252 (Ser49Gly), and used logistic regression to examine the association between genotypes and PoAF occurring within 14 days after surgery, before and after adjustment for demographic and clinical covariates.

RESULTS

Postoperative atrial fibrillation occurred in 239 patients (25.2%) and was associated with rs1801253 genotype (adjusted P = .008), with Gly389Gly having an odds ratio of 2.63 (95% CI 1.42-4.89) for PoAF compared to the common Arg389Arg (P = .002). In a predefined subgroup analysis, this association appeared to be stronger among patients without β-blocker prophylaxis (adjusted odds ratio 7.00, 95% CI 1.82-26.96, P = .005) compared to patients with β-blocker prophylaxis, among whom the association between rs1801253 genotype and PoAF was not statistically significant (adjusted P = .11).

CONCLUSION

The Gly389 variant in the β1-adrenoreceptor is associated with PoAF, and this association appears to be modulated by β-blocker therapy. Future studies of the association of other adrenergic pathway genes with PoAF will be of interest.