Associations of obesity and body fat distribution with incident atrial fibrillation in the biracial health aging and body composition cohort of older adults

Exploring the association between regional fat distribution and atrial fibrillation risks: a comprehensive cohort study

Background

The contribution of total fat mass and regional fat distribution to the risk of AF has rarely been studied.

Methods

This prospective cohort study(N=494,063) evaluated the association of total fat mass measured by fat percentage (FP) and regional fat measured by arm fat percentage (AFP), trunk fat percentage (TFP), and leg fat percentage (LFP) with incident AF. A subgroup (N = 25,581) underwent MRI, which allowed us to further assess whether visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (ASAT) of the trunk fat exert different effects on AF incidence.

Results

Over, a median 12.9 ± 1.86 years of follow-up, 29,658 participants (cumulative rate: 6.0%) developed AF. Each 1-standard deviation (SD) increase in LFP was associated with a 16% lower risk of AF (HR: 0.84, 95% CI: 0.82, 0.85). The association between FP and AF was weaker than that between LFP and AF (HR: 0.90, 95% CI: 0.89, 0.92). AFP and TFP only had a marginal association with a lower incidence of AF. Both the VAT and ASAT showed a U-shaped relationship with incident AF.

Conclusions

Fat mass, mainly leg fat mass, was associated with a lower risk of AF. ASAT did not exert protective effects.

Adiposity-associated atrial fibrillation: molecular determinants, mechanisms, and clinical significance

Obesity is an important contributing factor to the pathophysiology of atrial fibrillation (AF) and its complications by causing systemic changes, such as altered haemodynamic, increased sympathetic tone, and low-grade chronic inflammatory state. In addition, adipose tissue is a metabolically active organ that comprises various types of fat deposits with discrete composition and localization that show distinct functions. Fatty tissue differentially affects the evolution of AF, with highly secretory active visceral fat surrounding the heart generally having a more potent influence than the rather inert subcutaneous fat. A variety of proinflammatory, profibrotic, and vasoconstrictive mediators are secreted by adipose tissue, particularly originating from cardiac fat, that promote atrial remodelling and increase the susceptibility to AF. In this review, we address the role of obesity-related factors and in particular specific adipose tissue depots in driving AF risk. We discuss the distinct effects of key secreted adipokines from different adipose tissue depots and their participation in cardiac remodelling. The possible mechanistic basis and molecular determinants of adiposity-related AF are discussed, and finally, we highlight important gaps in current knowledge, areas requiring future investigation, and implications for clinical management.

Genetic Predisposition to a Higher Whole Body Water Mass May Increase the Risk of Atrial Fibrillation: A Mendelian Randomization Study

BACKGROUND

Observational studies have found an association between increased whole body water mass (BWM) and atrial fibrillation (AF). However, the causality has yet to be confirmed. To provide feasible protective measures on disease development, we performed Mendelian randomization (MR) design to estimate the potential causal relationship between increased BWM and AF.

METHODS

We implemented a two-sample MR study to assess whether increased BWM causally influences AF incidence. For exposure, 61 well-powered genetic instruments extracted from UK Biobank (N = 331,315) were used as the proxies of BWM. Summary genetic data of AF were obtained from FinnGen (Ncase = 22,068; Ncontrol = 116,926). Inverse-variance weighted (IVW), MR-Egger and weighted median methods were selected to infer causality, complemented with a series of sensitivity analyses. MR-Pleiotropy Residual Sum and Outlier (MR-PRESSO) and Radial MR were employed to identify outliers. Furthermore, risk factor analyses were performed to investigate the potential mechanisms between increased BWM and AF.

RESULTS

Genetic predisposition to increased BWM was demonstrated to be significantly associated with AF in the IVW model (OR = 2.23; 95% CI = 1.47-3.09; p = 1.60 × 10^-7), and the result was consistent in other MR approaches. There was no heterogeneity or pleiotropy detected in sensitivity analysis. MR-PRESSO identified no outliers with potential pleiotropy after excluding outliers by Radial MR. Furthermore, our risk factor analyses supported a positive causal effect of genetic predicted increased BWM on edematous diseases.

CONCLUSIONS

MR estimates showed that a higher BWM could increase the risk of AF. Pathological edema is an important intermediate link mediating this causal relationship.

Atrial fibrillation: Epidemiology, pathophysiology, and clinical complications (literature review)

The last three decades have been characterized by an exponential increase in knowledge and advances in the clinical management of atrial fibrillation. The purpose of the study is to provide an overview of the pathogenesis of nonvalvular atrial fibrillation and a comprehensive investigation of the epidemiological data associated with various risk factors for atrial fibrillation. The leading research methods are analysis and synthesis, comparison, observation, induction and deduction, and grouping method. Research has shown that old age, male gender, and European descent are important risk factors for developing atrial fibrillation. Other modifiable risk factors include a sedentary lifestyle, smoking, obesity, diabetes mellitus, obstructive sleep apnea, and high blood pressure predisposing to atrial fibrillation, and each has been shown to induce structural and electrical atrial remodeling. Both heart failure and myocardial infarction increase the risk of developing atrial fibrillation and vice versa creating feedback that increases mortality. The review is a comprehensive study of the epidemiological data linking nonmodifiable and modifiable risk factors for atrial fibrillation, and the pathophysiological data supporting the relationship between each risk factor and the occurrence of atrial fibrillation. This may be necessary for the practice of the treatment of the cardiac system.

Epicardial Adipose Tissue and Cardiac Arrhythmias: Focus on Atrial Fibrillation

Atrial Fibrillation (AF) is the most frequent cardiac arrhythmia and its prevalence increases with age. AF is strongly associated with an increased risk of stroke, heart failure and cardiovascular mortality. Among the risk factors associated with AF onset and severity, obesity and inflammation play a prominent role. Numerous recent evidence suggested a role of epicardial adipose tissue (EAT), the visceral fat depot of the heart, in the development of AF. Several potential arrhythmogenic mechanisms have been attributed to EAT, including myocardial inflammation, fibrosis, oxidative stress, and fat infiltration. EAT is a local source of inflammatory mediators which potentially contribute to atrial collagen deposition and fibrosis, the anatomical substrate for AF. Moreover, the close proximity between EAT and myocardium allows the EAT to penetrate and generate atrial myocardium fat infiltrates that can alter atrial electrophysiological properties. These observations support the hypothesis of a strong implication of EAT in structural and electrical atrial remodeling, which underlies AF onset and burden. The measure of EAT, through different imaging methods, such as echocardiography, computed tomography and cardiac magnetic resonance, has been proposed as a useful prognostic tool to predict the presence, severity and recurrence of AF. Furthermore, EAT is increasingly emerging as a promising potential therapeutic target. This review aims to summarize the recent evidence exploring the potential role of EAT in the pathogenesis of AF, the main mechanisms by which EAT can promote structural and electrical atrial remodeling and the potential therapeutic strategies targeting the cardiac visceral fat.

Independent effects of adiposity measures on risk of atrial fibrillation in men and women: a study of 0.5 million individuals

BACKGROUND

Atrial fibrillation (AF) has a higher prevalence in men than in women and is associated with measures of adiposity and lean mass (LM). However, it remains uncertain whether the risks of AF associated with these measures vary by sex.

METHODS

Among 477 904 UK Biobank participants aged 40-69 without prior AF, 23 134 incident AF cases were identified (14 400 men, 8734 women; median follow-up 11.1 years). Cox proportional hazards models were used to estimate the covariate adjusted hazard ratios (HRs) describing the association of AF with weight, measures of adiposity [fat mass (FM), waist circumference (WC)] and LM, and their independent relevance, by sex.

RESULTS

Weight and WC were independently associated with risk of AF [HR: 1.25 (1.23-1.27) per 10 kg, HR: 1.11 (1.09-1.14) per 10 cm, respectively], with comparable effects in both sexes. The association with weight was principally driven by LM, which, per 5 kg, conferred double the risk of AF compared with FM when mutually adjusted [HR: 1.20 (1.19-1.21), HR: 1.10 (1.09-1.11), respectively]; however, the effect of LM was weaker in men than in women (p-interaction = 4.3 x 10-9). Comparing the relative effects of LM, FM and WC identified different patterns within each sex; LM was the strongest predictor for both, whereas WC was stronger than FM in men but not in women.

CONCLUSIONS

LM and FM (as constituents of weight) and WC are risk factors for AF. However, the independent relevance of general adiposity for AF was more limited in men than in women. The relevance of both WC and LM suggests a potentially important role for visceral adiposity and muscle mass in AF development.

Inflammation and Cardiovascular Diseases in the Elderly: The Role of Epicardial Adipose Tissue

Human aging is a complex phenomenon characterized by a wide spectrum of biological changes which impact on behavioral and social aspects. Age-related changes are accompanied by a decline in biological function and increased vulnerability leading to frailty, thereby advanced age is identified among the major risk factors of the main chronic human diseases. Aging is characterized by a state of chronic low-grade inflammation, also referred as inflammaging. It recognizes a multifactorial pathogenesis with a prominent role of the innate immune system activation, resulting in tissue degeneration and contributing to adverse outcomes. It is widely recognized that inflammation plays a central role in the development and progression of numerous chronic and cardiovascular diseases. In particular, low-grade inflammation, through an increased risk of atherosclerosis and insulin resistance, promote cardiovascular diseases in the elderly. Low-grade inflammation is also promoted by visceral adiposity, whose accumulation is paralleled by an increased inflammatory status. Aging is associated to increase in epicardial adipose tissue (EAT), the visceral fat depot of the heart. Structural and functional changes in EAT have been shown to be associated with several heart diseases, including coronary artery disease, aortic stenosis, atrial fibrillation, and heart failure. EAT increase is associated with a greater production and secretion of pro-inflammatory mediators and neuro-hormones, so that thickened EAT can pathologically influence, in a paracrine and vasocrine manner, the structure and function of the heart and is associated to a worse cardiovascular outcome. In this review, we will discuss the evidence underlying the interplay between inflammaging, EAT accumulation and cardiovascular diseases. We will examine and discuss the importance of EAT quantification, its characteristics and changes with age and its clinical implication.

Relation of Abdominal Obesity to Risk of Atrial Fibrillation (From the Reasons for Geographic and Racial Differences in Stroke [REGARDS] Study)

Our knowledge of the association between abdominal obesity (AO) and the risk of atrial fibrillation (AF) after adjusting for body mass index (BMI) is limited. We included 11,617 Black and White participants (mean age 63.0 ± 8.4 years) from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) national cohort study who were free of AF at baseline. A multivariable logistic regression model was used to estimate the odds ratio (OR) with 95% confidence interval (CI) of incident AF associated with AO. We also evaluated the association between waist circumference (WC) and incident AF. Over a median follow-up of 9.4 years, 999 participants developed AF. AO was associated with an increased risk of AF in a multivariable model adjusted for sociodemographic, lifestyle, and cardiovascular risk factors (OR 1.43, 95% CI 1.24 to 1.65, p <0.001). The association was attenuated after adjusting for BMI (OR 1.13, 95% CI 0.95 to 1.35, p = 0.16). There was no evidence of interaction between AO and incident AF by age category (age >65 vs age ≤65), gender, race, obesity, or BMI category. Conversely, a 10cm increase in WC was associated with a higher incidence of AF after controlling for BMI (OR 1.18 95% CI 1.09 to 1.29, p <0.001), in both nonobese (OR 1.14, 95% CI 1.03 to 1.28, p = 0.02) and obese (OR 1.26, 95% CI 1.11 to 1.42, p <0.001) people. In conclusion, there was an association between AO and incident AF, but the association was weakened after adjusting for BMI. There was a significant association between WC and incident AF, after taking other AF risk factors and BMI into account. WC is a potentially modifiable risk factor for AF, and further research is warranted to explore the effect of decreasing WC on the population AF burden.

Sex-specific relationship between abdominal obesity and new-onset atrial fibrillation in the general Japanese population

The incidence of atrial fibrillation (AF) is expected to increase with increasing obesity and number of geriatric patients in Japan. Although higher body mass index and abdominal obesity are associated with an increased risk of AF, the sex-specific relationship between abdominal obesity and new-onset AF is unclear. This study aimed to investigate the sex-specific relationship between abdominal obesity and new-onset AF. This retrospective study evaluated the annual health checkup data of 67,379 adults (33,562 males; age, 54 ± 10 years) without baseline AF from April 2008 to March 2016. Participants were grouped according to waist circumference (WC): large-WC group (males, ≥ 85 cm; females, ≥ 90 cm) and normal-WC group. Logistic regression analyses were performed to determine the strength of the association between abdominal obesity and new-onset AF, overall and separately for males and females. During a median follow-up of 5 years, 280 (0.4%) new cases of AF were recorded. Univariate analysis revealed a significant increase in new-onset AF in males (odds ratio [OR], 1.97; 95% confidence interval [CI], 1.49-2.60; p < 0.001) but not in females (OR, 1.69; 95% CI, 0.96-2.97; p = 0.068) in the large-WC group. After adjusting for clinical variables, multivariate analysis revealed that a large WC was significantly associated with new-onset AF in males (OR, 1.76; 95% CI, 1.31-2.36; p < 0.001) but not in females (OR, 1.22; 95% CI, 0.68-2.18; p = 0.514). Abdominal obesity is associated with an increased risk of new-onset AF in men.

Joint Associations Between Body Mass Index and Waist Circumference With Atrial Fibrillation in Men and Women

Background Associations between adiposity and atrial fibrillation (AF) might differ between sexes. We aimed to determine precise estimates of the risk of AF by body mass index (BMI) and waist circumference (WC) in men and women. Methods and Results Between 2008 and 2013, over 3.2 million adults attended commercial screening clinics. Participants completed health questionnaires and underwent physical examination along with cardiovascular investigations, including an ECG. We excluded those with cardiovascular and cardiac disease. We used multivariable logistic regression and determined joint associations of BMI and WC and the risk of AF in men and women by comparing likelihood ratio χ2 statistics. Among 2.1 million included participants 12 067 (0.6%) had AF. A positive association between BMI per 5 kg/m2 increment and AF was observed, with an odds ratio of 1.65 (95% CI, 1.57-1.73) for men and 1.36 (95% CI, 1.30-1.42) for women among those with a BMI above 20 kg/m2. We found a positive association between AF and WC per 10 cm increment, with an odds ratio of 1.47 (95% CI, 1.36-1.60) for men and 1.37 (95% CI, 1.26-1.49) for women. Improvement of likelihood ratio χ2 was equal after adding BMI and WC to models with all participants. In men, WC showed stronger improvement of likelihood ratio χ2 than BMI (30% versus 23%). In women, BMI showed stronger improvement of likelihood ratio χ2 than WC (23% versus 12%). Conclusions We found a positive association between BMI (above 20 kg/m2) and AF and between WC and AF in both men and women. BMI seems a more informative measure about risk of AF in women and WC seems more informative in men.

Prehabilitative Exercise for the Enhancement of Physical, Psychosocial, and Biological Outcomes Among Patients Diagnosed with Cancer

PURPOSE OF REVIEW

This review summarizes the effects of prehabilitative exercise interventions on the physical, psychosocial, and biological outcomes among patients with cancer. Current gaps and future directions in prehabilitative exercise research will be addressed.

RECENT FINDINGS

Prehabilitative exercise mitigates the detrimental impact of cancer surgery on physical fitness, noted by increases in maximal oxygen consumption and 6-min walk distance. Beneficial effects on psychosocial and biological outcomes remain inconclusive. Aerobic exercise interventions were often prescribed and included low-, moderate-, or high-intensity exercise. Resistance exercise interventions were often performed in conjunction with aerobic exercise. Prehabilitative exercise elicits robust improvements in physical fitness; however, effect on psychosocial and biological outcomes remains inconclusive. Exercise prescription parameters varied greatly by frequency, intensity, time, and type across multiple cancer diagnoses. Future investigations are needed to systematically dose exercise for a wider variety of outcome measures, with an overall goal to set forth pre-operative exercise guidelines.

Association of Obesity Measures with Atrial Fibrillation Recurrence After Cryoablation in Patients with Paroxysmal Atrial Fibrillation

BACKGROUND Obesity increases the risk of atrial fibrillation (AF) recurrence after ablation. This study explored the relationship between various obesity indexes and risk of recurrence after cryoablation of paroxysmal AF (PAF). MATERIAL AND METHODS Our prospective study included 100 patients with PAF who underwent first cryoablation. Physical examination and fasting blood lipids levels were measured at baseline. Seven obesity indexes were determined: body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), waist-hip ratio (WHR), cardiometabolic index (CMI), lipid accumulation product (LAP), and body adiposity index (BAI). AF recurrence was confirmed by electrocardiograms and Holter monitor at follow-up visits after the initial 3-month blanking period. Receiver operating characteristic (ROC) curves were drawn to assess the abilities of obesity indicators in predicting AF recurrence. Multivariable Cox regression analysis was used to examine independent predictors of AF recurrence. RESULTS During a mean follow-up of 13.4 months, 31 patients (31.0%) had recurrent AF. Patients with recurrence had higher BMI, WC, WHtR, LAP, and BAI compared with those without recurrence. ROC analysis indicated the potential predictive value of BAI with an AUC of 0.657 (95% confidence interval [CI]: 0.534-0.779), followed by WC, WHtR, LAP, and BMI (all P<0.05). Diagnosis-to-ablation time (HR 1.034, 95% CI: 1.002-1.068), left atrial diameter (HR 1.147, 95% CI: 1.026-1.281), and WC (HR 1.026, 95% CI: 1.000-1.053) were independent predictive factors for AF recurrence after multivariable adjustment. CONCLUSIONS In this study population, WC appears to be a potential indicator for the prediction of recurrence in patients with PAF after cryoablation.

Atrial fibrillation is associated with lean body mass in postmenopausal women

This study investigated the association between body composition and risk of atrial fibrillation (AF) in postmenopausal women. In a retrospective analysis we assessed data from 5704 postmenopausal women (age 70.7 ± 6.5 yrs.) who in 1999–2001 participated in The Prospective Epidemiological Risk Factor study with body composition assessed by dual-energy X-ray absorptiometry. Outcomes were obtained from Danish Health Registries and body composition association to risk of AF was evaluated by univariable and multivariable Cox Hazard regression. 850 women developed AF after baseline. High lean body mass was associated with increased risk of AF in multivariable analyses, adjusting for body mass index (BMI), height or weight (adjusted for: BMI, hazard ratio (HR) 1.49, 95% Confidence Interval (1.22–1.80); height, HR 1.27 (1.03–1.56); weight, 1.33 (1.06–1.65)). Height and weight were associated with increased risk of AF in multivariable analyses adjusting for body composition measures. When adjusting for total lean mass, only height remained statistically significant (HR 1.34 (1.09–1.64)). In a cohort of elderly Caucasian women, high lean body mass, height and weight were associated with increased risk of AF and the variables remained significant after adjusting for age and other known risk factors of AF.

Racial Differences in Atrial Fibrillation Epidemiology, Management, and Outcomes

PURPOSE OF THE REVIEW

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice and is associated with significant morbidity and healthcare cost. Most of the AF studies have predominantly included white population, with under-representation of minority population. In this review, we analyze the racial differences in epidemiology, disease awareness, risk factors, genetics, treatments, and outcomes of AF.

RECENT FINDINGS

African Americans have a higher prevalence of established AF risk factors but lower incidence and prevalence of AF than non-Hispanic whites. There is also a significant racial and ethnic differences in the prevalence of AF-related symptoms and the detection and awareness of AF. Non-white patients are afforded decreased use of rhythm control treatment strategies and anticoagulation both with warfarin and NOACs for stroke prevention. They are less likely to receive catheter ablation (CA) of AF, compared with non-Hispanic whites. AF in the minority racial and ethnic groups carries increased morbidity and mortality compared with white groups, especially in the black individuals with AF, who have been shown to have a lower QoL compared with their white or Hispanic counterparts. Minorities experience stroke more frequently than the whites which is usually more severe and disabling. There are significant racial differences in AF risk factors, manifestations, management, and outcomes. Recognition of these differences will aid in developing better preventive and treatment strategies for AF to decrease morbidity and mortality. In addition, this knowledge will enhance our understanding regarding the pathophysiology of AF including genetic predisposition.

Cardiac overexpression of perilipin 2 induces atrial steatosis, connexin 43 remodeling, and atrial fibrillation in aged mice

Atrial fibrillation (AF) is prevalent in patients with obesity and diabetes, and such patients often exhibit cardiac steatosis. Since the role of cardiac steatosis per se in the induction of AF has not been elucidated, the present study was designed to explore the relation between cardiac steatosis and AF. Transgenic (Tg) mice with cardiac-specific overexpression of perilipin 2 (PLIN2) were housed in the laboratory for more than 12 mo before the study. Electron microscopy of the atria of PLIN2-Tg mice showed accumulation of small lipid droplets around mitochondrial chains, and five- to ninefold greater atrial triacylglycerol (TAG) content compared with wild-type (WT) mice. Electrocardiography showed significantly longer RR intervals in PLIN2-Tg mice than in WT mice. Transesophageal electrical burst pacing resulted in significantly higher prevalence of sustained (>5 min) AF (69%) in PLIN2-Tg mice than in WT mice (24%), although it was comparable in younger (4-mo-old) mice. Connexin 43 (Cx43), a gap junction protein, was localized at the intercalated disks in WT atria but was heterogeneously distributed on the lateral side of cardiomyocytes in PLIN2-Tg atria. Langendorff-perfused hearts using the optical mapping technique showed slower and heterogeneous impulse propagation in PLIN2-Tg atria compared with WT atria. Cardiac overexpression of hormone-sensitive lipase in PLIN2-Tg mice resulted in atrial TAG depletion and amelioration of AF susceptibility. The results suggest that PLIN2-induced steatosis is associated with Cx43 remodeling, impaired conduction propagation, and higher incidence of AF in aged mice. Therapies targeting cardiac steatosis could be potentially beneficial against AF in patients with obesity or diabetes.

The Impact of Metabolic Syndrome on the Incidence of Atrial Fibrillation: A Nationwide Longitudinal Cohort Study in South Korea

Aims: To evaluate the impact of metabolic syndrome (MetS) status on the incidence of atrial fibrillation (AF) in Koreans. Methods and results: Data obtained from the Korean National Health Insurance Service from 2009 to 2016 were analyzed. In total, 7,830,602 men and women (between 30 and 69 years of age) without baseline AF who underwent a national health examination between January 2009 and December 2009 were enrolled. Patients were evaluated to determine the impact of MetS status on their risk of developing AF until December 2016. Using the National Cholesterol Education Program Adult Treatment Panel III criteria, patients were placed into one of three groups depending on MetS component numbers: 0 (normal), 1–2 (Pre-MetS) or 3–5 (MetS). During a mean follow-up of 7.3 years, 20,708 subjects (0.26%) were diagnosed with AF. After multivariable adjustment, the risk of AF was significantly and positively correlated with MetS status (hazard ratios (HR) 1.391, 95% confidence interval (CI) 1.322–1.464 in Pre-MetS and HR 1.722, 95% CI 1.621–1.829 in MetS). When subgroup analyses were conducted according to MetS components, abdominal obesity (HR 1.316, p < 0.001), elevated blood pressure (HR 1.451, p < 0.001), and elevated fasting glucose (HR 1.163, p < 0.001) were associated with an increased risk of AF. Conclusion: MetS and pre-MetS are significantly associated with an increased risk of AF in Korean adults. Of the MetS components, abdominal obesity, elevated blood pressure, and elevated fasting glucose are potent risk factors for the risk of AF in this population.

Relation of Body Mass Index to Development of Atrial Fibrillation in Hispanics, Blacks, and Non-Hispanic Whites

No previous studies have examined the interaction between body mass index (BMI) and race/ethnicity with the risk of atrial fibrillation (AF). We retrospectively followed 48,323 persons free of AF (43% Hispanic, 37% black, and 20% white; median age 60 years) for subsequent incident AF (ascertained from electrocardiograms). BMI categories included very severely underweight (BMI <15 kg/m²), severely underweight (BMI 15.1 to 15.9 kg/m²), underweight (BMI 16 to 18.4 kg/m²), normal (BMI 18.5 to 24.9 kg/m²), overweight (BMI 25.0 to 29.9 kg/m²), moderately obese (BMI 30 to 34.9 kg/m²), severely obese (BMI 35 to 39.9 kg/m²), and very severely obese (BMI >40 kg/m²). Cox regression analysis controlled for baseline covariates: heart failure, gender, age, treatment for hypertension, diabetes, PR length, systolic blood pressure, left ventricular hypertrophy, socioeconomic status, use of β blockers, calcium channel blockers, and digoxin. Over a follow-up of 13 years, 4,744 AF cases occurred. BMI in units of 10 was associated with the development of AF (adjusted hazard ratio 1.088, 95% confidence interval 1.048 to 1.130, p <0.01). When stratified by race/ethnicity, non-Hispanic whites compared with blacks and Hispanics had a higher risk of developing AF, noted in those whom BMI classes were overweight to severely obese. In conclusion, our study demonstrates that there exists a relation between obesity and race/ethnicity for the development of AF. Non-Hispanic whites had a higher risk of developing AF compared with blacks and Hispanics.

Height, Weight, and Aerobic Fitness Level in Relation to the Risk of Atrial Fibrillation

Tall stature and obesity have been associated with a higher risk of atrial fibrillation (AF), but there have been conflicting reports of the effects of aerobic fitness. We conducted a national cohort study to examine interactions between height or weight and level of aerobic fitness among 1,547,478 Swedish military conscripts during 1969-1997 (97%-98% of all 18-year-old men) in relation to AF identified from nationwide inpatient and outpatient diagnoses through 2012 (maximal age, 62 years). Increased height, weight, and aerobic fitness level (but not muscular strength) at age 18 years were all associated with a higher AF risk in adulthood. Positive additive and multiplicative interactions were found between height or weight and aerobic fitness level (for the highest tertiles of height and aerobic fitness level vs. the lowest, relative excess risk = 0.51, 95% confidence interval (CI): 0.40, 0.62; ratio of hazard ratios = 1.50, 95% CI: 1.34, 1.65). High aerobic fitness levels were associated with higher risk among men who were at least 186 cm (6 feet, 1 inch) tall but were protective among shorter men. Men with the combination of tall stature and high aerobic fitness level had the highest risk (for the highest tertiles vs. the lowest, adjusted hazard ratio = 1.70, 95% CI: 1.61, 1.80). These findings suggest important interactions between body size and aerobic fitness level in relation to AF and may help identify high-risk subgroups.

Obesity is associated with incident atrial fibrillation independent of gender: A meta-analysis

BACKGROUND

The prevalence of obesity is increasing among the general population. Obesity is associated with increased risk of several cardiovascular conditions, which in turn may increase the risk for atrial fibrillation (AF). We performed a meta-analysis of cohort studies that examined the effect of obesity on the incidence of AF. In addition, we examined the effect of obesity on the incidence of AF stratified by gender.

METHODS AND RESULTS

We searched the MEDLINE and EMBASE databases for studies evaluating the effect of obesity on AF. Pooled risk ratios (RR) with 95% confidence intervals (CI) were calculated using a random effects model. Sixteen trials involving 587,372 subjects were included in the analysis. Obesity was defined as body mass index >30 kg/m² . AF during follow-up developed in 5,751 of 91,031 (6.3%) obese subjects and in 15,346 of 496,341 (3.1%) nonobese subjects (RR = 1.51, 95% CI 1.35 to 1.68; P < 0.00001). Based on the pooled estimate across the studies, the effect of obesity on incident AF was similar in men (RR = 1.41, 95% 1.24 to 1.62; P < 0.00001) and women (RR = 1.53, 95% CI 1.19 to 1.97; P < 0.00001).

CONCLUSION

Obesity is associated with an increased risk of new-onset AF in susceptible individuals. This effect appears to be consistent in both genders. Further studies are warranted to examine the impact of weight loss interventions on the risk of developing AF.

Sex Differences and Similarities in Atrial Fibrillation Epidemiology, Risk Factors, and Mortality in Community Cohorts: Results From the BiomarCaRE Consortium (Biomarker for Cardiovascular Risk Assessment in Europe)

BACKGROUND

Atrial fibrillation (AF) is a common cardiac disease in aging populations with high comorbidity and mortality. Sex differences in AF epidemiology are insufficiently understood.

METHODS

In N=79 793 individuals without AF diagnosis at baseline (median age, 49.6 years; age range, 24.1-97.6 years; 51.7% women) from 4 community-based European studies (FINRISK, DanMONICA, Moli-sani Northern Sweden) of the BiomarCaRE consortium (Biomarker for Cardiovascular Risk Assessment in Europe), we examined AF incidence, its association with mortality, common risk factors, biomarkers, and prevalent cardiovascular disease, and their attributable risk by sex. Median follow-up time was 12.6 (to a maximum of 28.2) years.

RESULTS

Fewer AF cases were observed in women (N=1796; 4.4%), than in men (N=2465; 6.4%). Cardiovascular risk factor distribution and lipid profile at baseline were less beneficial in men than in women, and cardiovascular disease was more prevalent in men. Cumulative incidence increased markedly after the age of 50 years in men and after 60 years in women. The lifetime risk was similar (>30%) for both sexes. Subjects with incident AF had a 3.5-fold risk of death in comparison with those without AF. Multivariable-adjusted models showed sex differences for the association of body mass index and AF (hazard ratio per standard deviation increase, 1.18; 95% confidence interval [CI], 1.12-1.23 in women versus 1.31; 95% CI 1.25-1.38 in men; interaction P value of 0.001). Total cholesterol was inversely associated with incident AF with a greater risk reduction in women (hazard ratio per SD, 0.86; 95% CI, 0.81-0.90 versus 0.92; 95% CI, 0.88-0.97 in men; interaction P value of 0.023). No sex differences were seen for C-reactive protein and N-terminal pro B-type natriuretic peptide. The population-attributable risk of all risk factors combined was 41.9% in women and 46.0% in men. About 20% of the risk was observed for body mass index.

CONCLUSIONS

Lifetime risk of AF was high, and AF was strongly associated with increased mortality both in women and men. Body mass index explained the largest proportion of AF risk. Observed sex differences in the association of body mass index and total cholesterol with AF need to be evaluated for underlying pathophysiology and relevance to sex-specific prevention strategies.

Atrial Fibrillation in Women: Risks and Management

Atrial fibrillation (AF) is one of the most commonly occurring arrhythmias and a major modifiable risk factor for stroke, especially in women. While its prevalence is similar in both men and women, women unfortunately face a greater intrinsic AF-related risk of stroke than men do. This is likely one of the reasons that more women than men die from strokes, in addition to experiencing more new and recurrent strokes. Therefore, in women especially, it is imperative to diagnose and treat AF as early as possible. While its unreliable symptom profile and possible intermittent nature can make AF difficult to detect, proactive identification of risk factors and improved detection methods can help. Additionally, the use of risk stratification schemes for anticoagulant therapy, along with the efficacy of nonvitamin K antagonist anticoagulants can enable appropriate therapy to prevent stroke occurrence.

Lean Body Mass Is the Predominant Anthropometric Risk Factor for Atrial Fibrillation

BACKGROUND

Obesity is repeatedly emphasized as a risk factor for atrial fibrillation or flutter (AF). However, the underlying evidence may be questioned, as the obvious correlations between various anthropometric measures hamper identification of the characteristics that are biologically driving AF risk, and recent studies suggest that fat carries limited or no independent risk of AF.

OBJECTIVES

This study sought to assess mutually adjusted associations among AF risk and height, weight, body mass index, hip and waist circumference, waist-to-hip ratio, and bioelectrical impedance-derived measures of fat mass, lean body mass, and fat percentage.

METHODS

Anthropometric measures and self-reported life-style information were collected from 1993 to 1997 in a population-based cohort including 55,273 persons age 50 to 64 years who were followed in Danish registers until June 2013.

RESULTS

During a median of 17 years of follow-up, 3,868 persons developed AF. Adjusted hazard ratios per population SD difference (HRs) showed highly statistically significant, positive associations for all 9 anthropometric measures (HRs ranging from 1.08 [95% confidence interval (CI): 1.05 to 1.12] for waist-to-hip ratio to 1.37 [95% CI: 1.33 to 1.42] for lean body mass). Pairwise mutual adjustment of the 9 measures left the association for lean body mass virtually unchanged (lowest HR: 1.33 [95% CI: 1.28 to 1.39] when adjusting for height), whereas no other association remained substantial when adjusted for lean body mass (highest HR: 1.05 [95% CI: 1.01 to 1.10] for height).

CONCLUSIONS

Lean body mass was the predominant anthropometric risk factor for AF, whereas no association was observed for either of the obesity-related anthropometric measures after adjustment for lean body mass.

Associations of Abdominal Obesity and New-Onset Atrial Fibrillation in the General Population

BACKGROUND

Higher height and weight are known to be associated with higher risk of atrial fibrillation (AF); however, whether the risk of AF is related to abdominal obesity is unclear.

METHODS AND RESULTS

We studied 501 690 adults (mean age: 47.6±14.3 years; 250 664 women [50.0%]) without baseline AF in the National Sample Cohort released by the National Health Insurance Service in Korea. Body mass index (underweight defined as <18.5; normal, 18.5 to <25.0; overweight, 25.0 to <30.0; and obese, ≥30.0) and waist circumference (abdominal obesity defined as ≥90 cm for men and ≥80 cm for women) were evaluated. During a mean follow-up of 3.9±1.3 years, 3443 participants (1432 women [41.6%]) developed AF. In multivariable models adjusted for clinical variables, the AF risk of underweight, overweight, and obese individuals increased by 21% (95% confidence interval, 1.01-1.45, P=0.043), 14% (95% confidence interval, 1.06-1.23, P<0.001), and 52% (95% confidence interval, 1.30-1.78, P<0.001), respectively, compared with those with normal body mass index. AF risk with confounder-adjusted hazards for abdominal obesity was 18% (95% confidence interval, 1.10-1.27, P<0.001). The increased AF risk was present in abdominally obese individuals regardless of body mass index except for the obese group. In subgroup analysis, abdominal obesity by waist circumference conferred increased risk of new-onset AF, particularly in participants without comorbidities.

CONCLUSIONS

Abdominal obesity is an important, potentially modifiable risk factor for AF in nonobese Asian persons. These data suggest that interventions to decrease abdominal obesity may reduce the population burden of AF.

Are cardiovascular risk factors also associated with the incidence of atrial fibrillation? A systematic review and field synopsis of 23 factors in 32 population-based cohorts of 20 million participants

Established primary prevention strategies of cardiovascular diseases are based on understanding of risk factors, but whether the same risk factors are associated with atrial fibrillation (AF) remains unclear. We conducted a systematic review and field synopsis of the associations of 23 cardiovascular risk factors and incident AF, which included 84 reports based on 28 consented and four electronic health record cohorts of 20,420,175 participants and 576,602 AF events. We identified 3-19 reports per risk factor and heterogeneity in AF definition, quality of reporting, and adjustment. We extracted relative risks (RR) and 95 % confidence intervals [CI] and visualised the number of reports with inverse (RR [CI]<1.00), or direct (RR [CI]>1.00) associations. For hypertension (13/17 reports) and obesity (19/19 reports), there were direct associations with incident AF, as there are for coronary heart disease (CHD). There were inverse associations for non-White ethnicity (5/5 reports, with RR from 0.35 to 0.84 [0.82-0.85]), total cholesterol (4/13 reports from 0.76 [0.59-0.98] to 0.94 [0.90-0.97]; 8/13 reports with non-significant inverse associations), and diastolic blood pressure (2/11 reports from 0.87 [0.78-0.96] to 0.92 [0.85-0.99]; 5/11 reports with non-significant inverse associations), and direct associations for taller height (7/10 reports from 1.03 [1.02-1.05] to 1.92 [1.38-2.67]), which are in the opposite direction of known associations with CHD. A systematic evaluation of the available evidence suggests similarities as well as important differences in the risk factors for incidence of AF as compared with other cardiovascular diseases, which has implications for the primary prevention strategies for atrial fibrillation.

Atrial Fibrillation: Epidemiology, Pathophysiology, and Clinical Outcomes

The past 3 decades have been characterized by an exponential growth in knowledge and advances in the clinical treatment of atrial fibrillation (AF). It is now known that AF genesis requires a vulnerable atrial substrate and that the formation and composition of this substrate may vary depending on comorbid conditions, genetics, sex, and other factors. Population-based studies have identified numerous factors that modify the atrial substrate and increase AF susceptibility. To date, genetic studies have reported 17 independent signals for AF at 14 genomic regions. Studies have established that advanced age, male sex, and European ancestry are prominent AF risk factors. Other modifiable risk factors include sedentary lifestyle, smoking, obesity, diabetes mellitus, obstructive sleep apnea, and elevated blood pressure predispose to AF, and each factor has been shown to induce structural and electric remodeling of the atria. Both heart failure and myocardial infarction increase risk of AF and vice versa creating a feed-forward loop that increases mortality. Other cardiovascular outcomes attributed to AF, including stroke and thromboembolism, are well established, and epidemiology studies have championed therapeutics that mitigate these adverse outcomes. However, the role of anticoagulation for preventing dementia attributed to AF is less established. Our review is a comprehensive examination of the epidemiological data associating unmodifiable and modifiable risk factors for AF and of the pathophysiological evidence supporting the mechanistic link between each risk factor and AF genesis. Our review also critically examines the epidemiological data on clinical outcomes attributed to AF and summarizes current evidence linking each outcome with AF.

Characteristics and long-term catheter ablation outcome in long-standing persistent atrial fibrillation patients with non-pulmonary vein triggers

BACKGROUND

There are limited literatures regarding the non-pulmonary vein (NPV) triggers in long-standing persistent atrial fibrillation (LSPAF). The goal of the present study was to investigate the characteristics and long-term outcome of catheter ablation among these patients.

METHODS

The study included 776 patients (age 53.59±11.38years-old, 556 males) who received catheter ablation for drug-refractory atrial fibrillation (AF). We divided these patients into 3 groups. Group 1 consisted of 579 patients with paroxysmal AF (PAF), group 2 consisted of 103 patients with persistent AF (PerAF) and group 3 consisted of 94 patients with long-standing persistent AF (LSPAF). The average follow-up duration was 28.53±23.21months.

RESULTS

The clinical endpoint was the recurrence of atrial tachyarrhythmia. Among these 3 groups, higher percentages of male (93.6%, P<0.001), NPV triggers (44.7%, P<0.001), longer AF duration (6.65±6.72years, P=0.029), larger left atrium diameter (44.44±6.79mm, P<0.001), and longer procedure time (181.94±70.02min, P<0.001) were noted in LSPAF. After the first catheter ablation, the recurrence rate of AF was highest in LSPAF (Log Rank, P<0.001). Larger left atrium diameters (LAD) (P=0.006; HR: 1.063; CI: 1.018-1.111) and NPV triggers (P=0.035; HR: 1.707; 1.037-2.809) independently predicted AF recurrence in LSPAF.

CONCLUSIONS

Compared with PAF and PerAF, LSPAF had a higher incidence of NPV triggers and worse long-term outcome after catheter ablation. NPV triggers and LAD independently predicted AF recurrence after catheter ablation in LSPAF.

Body mass index, abdominal fatness, fat mass and the risk of atrial fibrillation: a systematic review and dose-response meta-analysis of prospective studies

Different adiposity measures have been associated with increased risk of atrial fibrillation, however, results have previously only been summarized for BMI. We therefore conducted a systematic review and meta-analysis of prospective studies to clarify the association between different adiposity measures and risk of atrial fibrillation. PubMed and Embase databases were searched up to October 24th 2016. Summary relative risks (RRs) were calculated using random effects models. Twenty-nine unique prospective studies (32 publications) were included. Twenty-five studies (83,006 cases, 2,405,381 participants) were included in the analysis of BMI and atrial fibrillation. The summary RR was 1.28 (95% confidence interval: 1.20-1.38, I² = 97%) per 5 unit increment in BMI, 1.18 (95% CI: 1.12-1.25, I² = 73%, n = 5) and 1.32 (95% CI: 1.16-1.51, I² = 91%, n = 3) per 10 cm increase in waist and hip circumference, respectively, 1.09 (95% CI: 1.02-1.16, I² = 44%, n = 4) per 0.1 unit increase in waist-to-hip ratio, 1.09 (95% CI: 1.02-1.16, I² = 94%, n = 4) per 5 kg increase in fat mass, 1.10 (95% CI: 0.92-1.33, I² = 90%, n = 3) per 10% increase in fat percentage, 1.10 (95% CI: 1.08-1.13, I² = 74%, n = 10) per 5 kg increase in weight, and 1.08 (95% CI: 0.97-1.19, I² = 86%, n = 2) per 5% increase in weight gain. The association between BMI and atrial fibrillation was nonlinear, p _nonlinearity < 0.0001, with a stronger association at higher BMI levels, however, increased risk was observed even at a BMI of 22-24 compared to 20. In conclusion, general and abdominal adiposity and higher body fat mass increase the risk of atrial fibrillation.

Reduced enhancement of high-frequency component in the cross spectrum of ECG and nostril airflow signals in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a chronic airway disease with increased airway resistance. This study investigated the common characteristics of electrocardiographic (ECG) and nostril airflow signals in COPD patients using cross-spectral analysis. Heart rate variability (HRV) measures and cross-spectral (cs) measures of ECG and nostril airflow were compared in COPD patients and normal subjects, and correlated with their clinical characteristics. We found that cross-spectral analysis can lead to a significant increase in normalized high-frequency power (nHFPcs) and a significant decrease in normalized very low-frequency power (nVLFPcs), normalized low-frequency power (nLFPcs), and low-/high-frequency power ratio (LHRcs) in both normal subjects and COPD patients, as compared with their corresponding HRV measures. Further analysis showed that the percentage increase in nHFP (%nHFP) and the percentage decrease in LHR (%LHR) due to cross-spectral analysis in COPD patients were significantly smaller than those of normal subjects. All cross-spectral measures of ECG and nostril airflow in COPD patients did not significantly correlate with their pulmonary function characteristics. However, the nHFPcs correlated significantly and negatively with body mass index (BMI) in both normal subjects and COPD patients, and the %nHFP correlated significantly and negatively with BMI in COPD patients. We conclude that cross-spectral analysis of ECG and nostril airflow signals could lead to reduced enhancement in the high-frequency component in the cross spectrum of COPD patients. The magnitude of reduced enhancement in the high-frequency component in the cross-spectrum was related to the BMI of the patients. Cross-spectral analysis of ECG and nostril airflow might be used to assess the cardiovascular-related functions of COPD patients.

Clinical significance of nutritional status in patients with atrial fibrillation: An overview of current evidence

BACKGROUND

Obesity is a well-known atherosclerosis risk factor; however, its role and the importance of undernutrition in atrial fibrillation (AF) pathogenesis are still not well understood. The aim of this study was to present the current state of knowledge on this issue in different groups of patients.

METHODS

Systematic review of papers published between 1980 and 2016.

RESULTS

The literature shows contradicting views regarding the impact of nutritional status on the risk, course, and complications of AF. On the one hand, it has been revealed that overweight, obesity, and high birth mass increase the risk of AF, and that their reduction is linked to an improved course of AF and reduced all-cause and cardiovascular mortality. On the other hand, a so-called obesity paradox has been found, which shows lower all-cause mortality in overweight patients with AF compared to those of normal weight or who are underweight. It has also been shown, although based on a small number of studies, that the relationship between nutritional status and risk of AF and its complication may be U-shaped, which means that not only patients with obesity, but also individuals with underweight, cachexia, and low birth weight may have an increased risk and poor outcome of AF.

CONCLUSIONS

The relationship between patients' nutritional status and the course of AF has become clearer but it requires further studies examining the importance of weight reduction on AF course.