Birth weight is a significant risk factor for incident atrial fibrillation

Birth weight influences cardiac structure, function, and disease risk: evidence of a causal association

BACKGROUND AND AIMS

Low birth weight is a common pregnancy complication, which has been associated with higher risk of cardiometabolic disease in later life. Prior Mendelian randomization (MR) studies exploring this question do not distinguish the mechanistic contributions of variants that directly influence birth weight through the foetal genome (direct foetal effects), vs. variants influencing birth weight indirectly by causing an adverse intrauterine environment (indirect maternal effects). In this study, MR was used to assess whether birth weight, independent of intrauterine influences, is associated with cardiovascular disease risk and measures of adverse cardiac structure and function.

METHODS

Uncorrelated (r2 < .001), genome-wide significant (P < 5 × 10-8) single nucleotide polymorphisms were extracted from genome-wide association studies summary statistics for birth weight overall, and after isolating direct foetal effects only. Inverse-variance weighted MR was utilized for analyses on outcomes of atrial fibrillation, coronary artery disease, heart failure, ischaemic stroke, and 16 measures of cardiac structure and function. Multiple comparisons were accounted for by Benjamini-Hochberg correction.

RESULTS

Lower genetically-predicted birth weight, isolating direct foetal effects only, was associated with an increased risk of coronary artery disease (odds ratio 1.21, 95% confidence interval 1.06-1.37; P = .031), smaller chamber volumes, and lower stroke volume, but higher contractility.

CONCLUSIONS

The results of this study support a causal role of low birth weight in cardiovascular disease, even after accounting for the influence of the intrauterine environment. This suggests that individuals with a low birth weight may benefit from early targeted cardiovascular disease prevention strategies, independent of whether this was linked to an adverse intrauterine environment during gestation.

Opposite causal effects of birthweight on myocardial infarction and atrial fibrillation and the distinct mediating pathways: a Mendelian randomization study

BACKGROUND

Previous observational studies have documented an inverse association of birthweight with myocardial infarction (MI) but a positive association with atrial fibrillation (AF). However, the causality of these associations and the underlying mediating pathways remain unclear. We aimed to investigate the causal effects of birthweight, incorporating both fetal and maternal genetic effects, on MI and AF, and identify potential mediators in their respective pathways.

METHODS

We performed Mendelian randomization (MR) analyses using genome-wide association study summary statistics for birthweight (N = 297,356 for own birthweight and 210,248 for offspring birthweight), MI (Ncase=61,000, Ncontrol=577,000), AF (Ncase=60,620, Ncontrol=970,216), and 52 candidate mediators (N = 13,848-1,295,946). Two-step MR was employed to identify and assess the mediation proportion of potential mediators in the associations of birthweight with MI and AF, respectively. As a complement, we replicated analyses for fetal-specific birthweight and maternal-specific birthweight.

RESULTS

Genetically determined each 1-SD lower birthweight was associated with a 40% (95% CI: 1.22-1.60) higher risk of MI, whereas each 1-SD higher birthweight was causally associated with a 29% (95% CI: 1.16-1.44) higher risk of AF. Cardiometabolic factors, including lipids and lipoproteins, glucose and insulin, blood pressure, and fatty acids, each mediated 4.09-23.71% of the total effect of birthweight on MI, followed by body composition and strength traits (i.e., appendicular lean mass, height, and grip strength) and socioeconomic indicators (i.e., education and household income), with the mediation proportion for each factor ranging from 8.08 to 16.80%. By contrast, appendicular lean mass, height, waist circumference, childhood obesity, and body mass index each mediated 15.03-45.12% of the total effect of birthweight on AF. Both fetal-specific birthweight and maternal-specific birthweight were inversely associated with MI, while only fetal-specific birthweight was positively associated with AF. Psychological well-being and lifestyle factors conferred no mediating effect in either association.

CONCLUSIONS

Cardiometabolic factors mainly mediated the association between lower birthweight and MI, while body composition and strength traits mediated the association between higher birthweight and AF. These findings provide novel evidence for the distinct pathogenesis of MI and AF and advocate adopting a life-course approach to improving fetal development and subsequent causal mediators to mitigate the prevalence and burden of cardiovascular diseases.

The Association between Birthweight and Use of Cardiovascular Medications: The Role of Health Behaviors

BACKGROUND

There is limited evidence on the effect of low birthweight on the use of cardiovascular medications and the role of health behaviors. This study aims to determine the independent effect of low birthweight and its combination with adult health behaviors on the number of dispensed cardiovascular medications.

METHODS

We included 15618 participants with information on birthweight and self-reported health behaviors. Dispensed cardiovascular medications were identified from the Prescribed Drug Register based on a three-digit level Anatomical Therapeutic Chemical classification code (C01 to C10 and B01) and categorized into 0, 1, and ≥2 different types of medications. We applied multinomial logistic regression models estimating odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Participants with low birthweight had a higher estimated OR of using ≥2 types of cardiovascular medications (OR = 1.46, 95% CI = 1.06, 2.01). Further, an increased risk for using ≥2 types of cardiovascular medications was found in participants with poor health behaviors for normal (OR = 2.17, 95% CI = 1.80, 2.62) and high (OR = 1.84, 95% CI = 1.29, 2.62) birthweight. The strongest effect on using ≥2 types of cardiovascular medications was found for low birthweight and poor health behaviors (OR = 3.14, 95% CI = 1.80, 5.50).

CONCLUSION

This cohort study provides evidence that low birthweight increases the risk of using more types of cardiovascular medications in adulthood. This study also suggests that ideal health behaviors reduce this risk.

A Discussion of the Contemporary Prediction Models for Atrial Fibrillation

Atrial Fibrillation is a complex disease state with many environmental and genetic risk factors. While there are environmental factors that have been shown to increase an individual's risk of atrial fibrillation, it has become clear that atrial fibrillation has a genetic component that influences why some patients are at a higher risk of developing atrial fibrillation compared to others. This review will first discuss the clinical diagnosis of atrial fibrillation and the corresponding rhythm atrial flutter. We will then discuss how a patients' risk of stroke can be assessed by using other clinical co-morbidities. We will then review the clinical risk factors that can be used to help predict an individual patient's risk of atrial fibrillation. Many of the clinical risk factors have been used to create several different risk scoring methods that will be reviewed. We will then discuss how genetics can be used to identify individuals who are at higher risk for developing atrial fibrillation. We will discuss genome-wide association studies and other sequencing high-throughput sequencing studies. Finally, we will touch on how genetic variants derived from a genome-wide association studies can be used to calculate an individual's polygenic risk score for atrial fibrillation. An atrial fibrillation polygenic risk score can be used to identify patients at higher risk of developing atrial fibrillation and may allow for a reduction in some of the complications associated with atrial fibrillation such as cerebrovascular accidents and the development of heart failure. Finally, there is a brief discussion of how artificial intelligence models can be used to predict which patients will develop atrial fibrillation.

Birth weight and subclinical cardiovascular and renal damage in a population-based study (the STANISLAS cohort study)

OBJECTIVE

Although preterm-born and low-birth-weight individuals have an increased risk of cardiovascular diseases in adulthood, little is known regarding early cardiovascular and renal damage (CVRD) or hypertension in adulthood. Our study investigated the association of birth weight with early CVRD markers as well as the heritability of birth weight in an initially healthy family-based cohort.

METHODS

This study was based on 1028 individuals from the familial longitudinal STANISLAS cohort (399 parents/629 children) initiated in 1993-1995, with a fourth examination conducted in 2011-2016. Analyses performed at the fourth visit included pulse-wave velocity, central pressure, ambulatory blood pressure, hypertension status, diastolic dysfunction/distensibility, left ventricular mass indexed (LVMI), carotid intima-media thickness and kidney damage. The family structure of the cohort allowed birth weight heritability estimation.

RESULTS

Mean (±SD) birth weight was 3.3 ± 0.6 kg. Heritability was moderate (42-44%). At the fourth visit, individuals were 37 years old (32.0-57.0), 56% were women and 13% had antihypertensive treatment. Birth weight was strongly and negatively associated with hypertension [odds ratio (OR) 95% confidence interval (CI) 0.61 (0.45-0.84)]. A nonlinear association was found with LVMI, participants with a birth weight greater than 3 kg having a higher LVMI. A positive association ( β 95% CI 5.09 (1.8-8.38)] was also observed between birth weight and distensibility for adults with normal BMI. No associations were found with other CVRD.

CONCLUSION

In this middle-aged population, birth weight was strongly and negatively associated with hypertension, and positively associated with distensibility in adults with normal BMI and with LVMI for higher birth weights. No associations were found with other CVRD markers.

Preterm Birth, Small for Gestational Age, and Large for Gestational Age and the Risk of Atrial Fibrillation Up to Middle Age

Importance

Adverse birth outcomes, including preterm birth, small for gestational age (SGA), and large for gestational age (LGA) are associated with increased risks of hypertension, ischemic heart disease, stroke, and heart failure, but knowledge regarding their associations with atrial fibrillation (AF) is limited and inconsistent.

Objective

To investigate whether preterm birth, SGA, or LGA are associated with increased risks of AF later in life.

Design, Setting, and Participants

This multinational cohort study included Danish, Swedish, and Finnish national health registries. Live singleton births in Denmark from 1978 through 2016, in Sweden from 1973 through 2014, and in Finland from 1987 through 2014, who were followed up until December 31, 2016, in Denmark, December 31, 2021, in Sweden, and December 31, 2014, in Finland were included. Data analyses were performed between January 2021 and August 2022.

Exposures

Preterm birth (less than 37 gestational weeks), SGA (less than 10th percentile birth weight for gestational age), and LGA (more than 90th percentile birth weight for gestational age) identified from medical birth registers.

Main Outcomes and Measures

Diagnosis of AF obtained from nationwide inpatient and outpatient registers. The study team ran multivariable Cox proportional hazard models and flexible parametric survival models to estimate hazard ratios (HRs) and 95% CIs for AF according to preterm birth, SGA, and LGA. Sibling analyses were conducted to control for unmeasured familial factors.

Results

The cohort included 8 012 433 study participants (maximum age, 49 years; median age, 21 years; male, 51.3%). In 174.4 million person-years of follow-up, 11 464 participants had a diagnosis of AF (0.14%; median age, 29.3 years). Preterm birth and LGA were associated with increased AF risk in both the full population cohort and in the sibling analyses; the multivariate HRs from the cohort analyses were 1.30 (95% CI, 1.18-1.42) and 1.55 (95% CI, 1.46-1.63), respectively. Preterm birth was more strongly associated with AF in childhood than in adulthood. Children born SGA had an increased risk of AF in the first 18 years of life but not afterwards.

Conclusions and Relevance

Preterm births and LGA births were associated with increased risks of AF up to middle age independently of familial confounding factors. Individuals born SGA had an increased AF risk only during childhood.

Associations of birth weight and later life lifestyle factors with risk of cardiovascular disease in the USA: A prospective cohort study

BACKGROUND

Low birth weight has been associated with a greater risk of cardiovascular disease (CVD). However, the interaction between low birth weight and adult lifestyle factors on the risk of CVD remains unclear.

METHODS

We included 20,169 men from the Health Professionals Follow-up Study (HPFS, 1986-2016), 52,380 women from the Nurses' Health Study (NHS, 1980-2018), and 85,350 women from the Nurses' Health Study II (NHS II, 1991-2017) in the USA who reported birth weight and updated data on adult body weight, smoking status, physical activity, and diet every 2-4 years. Incident cases of CVD, defined as a combined endpoint of fatal and nonfatal coronary heart disease (CHD) and stroke, were self-reported and confirmed by physicians through reviewing medical records.

FINDINGS

During 4,370,051 person-years of follow-up, 16,244 incident CVD cases were documented, including 12,126 CHD and 4118 stroke cases. Cox proportional hazards regression models revealed an increased risk of CHD during adulthood across categories of decreasing birth weight in all cohorts (all P for linear trend <0.001). Additionally, we found an additive interaction between decreasing birth weight and unhealthy lifestyles on the risk of CHD among women, with a pooled relative excess risk due to interaction of 0.06 (95% CI: 0.04-0.08). The attributable proportions of the joint effect were 23.0% (95% CI: 11.0-36.0%) for decreasing birth weight alone, 67.0% (95% CI: 58.0-75.0%) for unhealthy lifestyle alone, and 11.0% (95% CI: 5.0-17.0%) for their additive interaction. Lower birth weight was associated with a greater stroke risk only among women, which was independent of later-life lifestyle factors.

INTERPRETATION

Lower birth weight may interact synergistically with unhealthy lifestyle factors in adulthood to further increase the risk of CHD among women.

FUNDING

The National Institutes of Health grants.

Premature Atrial Contractions and Their Determinants in a General Population of Japanese Men

BACKGROUND

Premature atrial contractions (PACs) are predictors of atrial fibrillation, stroke, and cardiovascular mortality. The present study aimed to assess relevant factors for PACs among a general population of Japanese men.

METHODS AND RESULTS

This study conducted a population-based, cross-sectional study among 517 men, aged 40-79 years, with neither apparent myocardial infarction nor atrial fibrillation. 24-h Holter electrocardiography to assess PAC frequency was used. Age, body mass index, height, low-density lipoprotein cholesterol, triglycerides, high-density lipoprotein cholesterol, mean heart rate, diabetes mellitus, hypertension, physical activity, smoking, alcohol consumption, and lipid-lowering therapy were included in multivariable negative binomial regression analyses to assess correlation for the number of PACs per hour. Almost all participants (99%) had at least 1 PAC in 1 h (median number 2.84 PACs per h). In multivariable negative binomial regression after adjusting for all covariates simultaneously, age (relative risk [95% confidence interval], 1.30 [1.08-1.57] per 1-standard deviation [SD] increment), height (1.19 [1.02-1.39] per 1-SD increment), triglycerides (0.79 [0.65-0.97] per 1-SD increment), mean heart rate (0.69 [0.59-0.80] per 1-SD increment), physical activity (0.63 [0.43-0.93]), current smoking (1.69 [1.06-2.69]), current moderate (1.97 [1.23-3.16]) and heavy (1.84 [1.12-3.01]) alcohol consumption were independently associated with PAC frequency.

CONCLUSIONS

PAC frequency was independently associated with age, height, smoking, alcohol consumption, heart rate, physical activity, and triglycerides.

The Risk of Atrial Fibrillation Increases with Earlier Onset of Obesity: A Mendelian Randomization Study

Background: Obesity is a well-established risk factor for atrial fibrillation (AF). Previous epidemiological research on obesity and AF often focused on adult populations and now broadened to earlier in life. Therefore, this study aimed to determine the relationships between obesity at different periods of life and the risk of AF. Methods: A two-sample Mendelian randomization (MR) study design using summarised data from 6 genome-wide association studies (GWASs) was employed in this study. Single nucleotide polymorphisms (SNPs) associated with adult obesity, childhood obesity, childhood body mass index (BMI), waist-to-hip ratio adjusted for BMI (WHRadjBMI), birth weight and AF were independently retrieved from large-scale GWASs. For SNP identification, the genome-wide significance threshold was set at p <5.00×10^-8. To obtain causal estimates, MR analysis was conducted using the inverse variance-weighted (IVW) method. The weighted median, MR-Egger methods and MR-robust adjusted profile score (MR-RAPS) were used to evaluate the robustness of MR analysis. Results: A total of 204 SNPs were identified as the genetic instrumental variables (5 SNPs for childhood obesity, 13 SNPs for childhood BMI, 137 SNPs for birth weight, 35 SNPs for adult WHRadjBMI, and 14 SNPs for adult obesity). The results of MR analysis demonstrated that the genetically predicted adult obesity, childhood BMI, and birth weight were associated with AF risk. Notably, a 1 unit standard deviation (1-SD) increase in adult obesity was related to a 13% increased risk of AF [p=6.51×10^-7, OR, 1.13 (95% CI, 1.08-1.19)], a 1-SD increase in childhood BMI was related to a 18% increased risk of AF [p=1.77×10^-4, OR, 1.18 (95% CI, 1.08-1.29)], and a 1-SD increase in birth weight was related to a 26% increased risk of AF [p=1.27×10^-7, OR, 1.26 (95% CI, 1.16-1.37)]. There was no evidence of pleiotropy or heterogeneity between the MR estimates obtained from multiple SNPs. Conclusion: Our study reveals the association of genetic susceptibility to obesity with a higher risk of AF. Moreover, an earlier age at obesity was associated with an increased risk of AF. Therefore, public awareness of the dangers of obesity and active early weight control may prevent the development of AF.

Genetic Determinants of Increased Body Mass Index Partially Mediate the Effect of Elevated Birth Weight on the Increased Risk of Atrial Fibrillation

Background: Although several observational studies have shown an association between birth weight (BW) and atrial fibrillation (AF), controversy remains. In this study, we aimed to explore the role of elevated BW on the etiology of AF.

Methods: A two-sample Mendelian randomization (MR) study was designed to infer the causality. The genetic data on the associations of single-nucleotide polymorphisms (SNPs) with BW and AF were separately obtained from two large-scale genome-wide association studies with up to 321,223 and 1,030,836 individuals, respectively. SNPs were identified at a genome-wide significant level (p <5 × 10⁻⁸). The inverse variance-weighted (IVW) method was employed to obtain causal estimates as our primary analysis. Sensitivity analyses with various statistical methods were applied to evaluate the robustness of the results, and multivariable MR analysis was conducted to determine whether this association was mediated by the body mass index (BMI).

Results: In total, 144 SNPs were identified as the genetic instrumental variables. MR analysis revealed a causal effect of elevated BW on AF (OR = 1.27, 95% CI = 1.14–1.40, p = 5.70 × 10⁻⁶). All the results in sensitivity analyses were consistent with the primary result. The effect of BW on AF was attenuated when adjusted for BMI (OR = 1.16, 95% CI = 1.01–1.33, p = 0.04).

Conclusions: This study indicated that elevated BW was significantly associated with increased lifelong risk of AF, which may be partially mediated by BMI.

Low Birth Weight Increases the Risk of Sudden Cardiac Death in the Young: A Nationwide Study of 2.2 Million People

Background Sudden cardiac death (SCD) constitutes a major health problem worldwide. We investigated whether birth weight (BW), small for gestational age (SGA), and large for gestational age are associated with altered risk of SCD among the young (aged 1-36 years). Methods and Results We included all people born in Denmark from 1973 to 2008 utilizing the Danish Medical Birth Register. All SCDs in Denmark in 2000 to 2009 have previously been identified. We defined 5 BW groups, SGA, and large for gestational age as exposure and SCD as the outcome. We estimated the age-specific relative risk of SCD with 95% CI. Additionally, we investigated if SGA and large for gestational age are associated with pathological findings at autopsy. The study population for the BW analyses comprised 2 234 501 people with 389 SCD cases, and the SGA and large for gestational age analyses comprised 1 786 281 people with 193 SCD cases. The relative risk for SCD was 6.69 for people with BW between 1500 and 2499 g (95% CI, 2.38-18.80, P<0.001) and 5.89 for people with BW ≥4500 g (95% CI, 1.81-19.12, P=0.003) at age 5 years. BW 2500 to 3400 g was the reference group. Compared with an appropriate gestational age, the relative risk for SGA was 2.85 (95% CI, 1.35-6.00, P=0.006) at age 10 years. For the autopsied cases, the relative risk of sudden arrhythmic death syndrome at age 5 years was 4.19 for SGA (95% CI, 1.08-16.22, P=0.038). Conclusions We found an association between BW and SCD in the young, with an increased risk among SGA infants. In addition, we found an association between SGA and sudden arrhythmic death syndrome.

The Association Between High Birth Weight and Long-Term Outcomes-Implications for Assisted Reproductive Technologies: A Systematic Review and Meta-Analysis

Background: Studies have shown that the prevalence of children born with high birth weight or large for gestational age (LGA) is increasing. This is true for spontaneous pregnancies; however, children born after frozen embryo transfer (FET) as part of assisted reproductive technology (ART) also have an elevated risk. In recent years, the practice of FET has increased rapidly and while the perinatal and obstetric risks are well-studied, less is known about the long-term health consequences. Objective: The aim of this systematic review was to describe the association between high birth weight and LGA on long-term child outcomes. Data Sources: PubMed, Scopus, and Web of Science were searched up to January 2021. Exposure included high birth weight and LGA. Long-term outcome variables included malignancies, psychiatric disorders, cardiovascular disease, and diabetes. Study Selection: Original studies published in English or Scandinavian languages were included. Studies with a control group were included while studies published as abstracts and case reports were excluded. Data Extraction: The methodological quality, in terms of risk of bias, was assessed by pairs of reviewers. Robins-I (www.methods.cochrane.org) was used for risk of bias assessment in original articles. For systematic reviews, AMSTAR (www.amstar.ca) was used. For certainty of evidence, we used the GRADE system. The systematic review followed PRISMA guidelines. When possible, meta-analyses were performed. Results: The search included 11,767 articles out of which 173 met the inclusion criteria and were included in the qualitative analysis, while 63 were included in quantitative synthesis (meta-analyses). High birth weight and/or LGA was associated with low to moderately elevated risks for certain malignancies in childhood, breast cancer, several psychiatric disorders, hypertension in childhood, and type 1 and 2 diabetes. Conclusions: Although the increased risks for adverse outcome in offspring associated with high birth weight and LGA represent serious health effects in childhood and in adulthood, the size of these effects seems moderate. The identified risk association should, however, be taken into account in decisions concerning fresh and frozen ART cycles and is of general importance in view of the increasing prevalence in high birthweight babies.

Genetically Determined Birthweight Associates With Atrial Fibrillation: A Mendelian Randomization Study

BACKGROUND

Atrial fibrillation is a common cardiovascular disorder, characterized by irregular electrical activity in the upper chambers of the heart. Both chronic cardiometabolic risk factors and genetics have been shown to contribute to the development of atrial fibrillation. Birthweight has also been associated with risk of atrial fibrillation.

METHODS

In the current study, we utilized a genetic approach to study the effect of birthweight on atrial fibrillation. We used 2-sample Mendelian randomization to consider the impact of birthweight on incident atrial fibrillation using summary data from the Early Growth Genetics Consortium GWAS of birthweight and a large biobank-based GWAS of atrial fibrillation.

RESULTS

Using the framework of 2-sample Mendelian randomization, we found that a 1-SD genetic elevation of birthweight was associated with increased risk of atrial fibrillation (odds ratio, 1.27 [95% CI, 1.14-1.41]; P=1×10^-5) with sensitivity analyses demonstrating robustness of this result.

CONCLUSIONS

Our findings clarify the directionality of the relationship between birthweight and atrial fibrillation, supporting the growing body of evidence that intrauterine growth has a lifelong impact on cardiovascular health.

Levels of and Changes in Childhood Body Mass Index in Relation to Risk of Atrial Fibrillation and Atrial Flutter in Adulthood

Children with obesity have a cardiometabolic risk profile that may predispose them to cardiovascular diseases. We examined the associations of childhood body mass index (BMI) and changes in BMI with the risk of atrial fibrillation and flutter (AFF) in adulthood. We conducted a population-based cohort study of Danish schoolchildren aged 7-13 years born from 1930 to 1989. Among 314,140 children, 17,594 were diagnosed with AFF as adults (1977-2014). In both men and women, above-average BMIs in childhood were associated with increased risks of AFF. Children who were persistently heavy at ages 7 and 13 years and children whose BMIs increased from the internal 25.0th-75.0th percentiles or from the internal 75.1th-90.0th percentiles between ages 7 and 13 years had higher risks of AFF in adulthood than children whose BMIs remained in the internal 25.0th-75.0th percentiles at both ages. A decrease in BMI percentile categories between 7 and 13 years of age reduced risks of AFF in adulthood, with risks of AFF reverting to levels similar to those in the reference group for women but not for men. In conclusion, risks of AFF in adulthood increased with higher childhood BMIs. Remission from overweight by age 13 years reduced AFF risks, especially in women.

Early Life Risk Factors for Incident Atrial Fibrillation in the Helsinki Birth Cohort Study

Background

Early life risk factors are associated with cardiometabolic disease, but have not been fully studied in atrial fibrillation (AF). There are discordant results from existing studies of birth weight and AF, and the impact of maternal body size, gestational age, placental size, and birth length is unknown.

Methods and Results

The Helsinki Birth Cohort Study includes 13 345 people born as singletons in Helsinki in the years 1934–1944. Follow‐up was through national registries, and ended on December 31, 2013, with 907 incident cases. Cox regression analyses stratified on year of birth were constructed for perinatal variables and incident AF, adjusting for offspring sex, gestational age, and socioeconomic status at birth. There was a significant U‐shaped association between birth weight and AF (P for quadratic term=0.01). The lowest risk of AF was found among those with a birth weight of 3.4 kg (3.8 kg for women [85th percentile] and 3.0 kg for men [17th percentile]). High maternal body mass index (≥30 kg/m²) predicted offspring AF; hazard ratio 1.36 (95% CI 1.07–1.74, P=0.01) compared with normal body mass index (<25 kg/m²). Maternal height was associated with early‐onset AF (<65.3 years), hazard ratio 1.47 (95% CI 1.24–1.74, P<0.0001), but not with later onset AF. Results were independent of incident coronary artery disease, hypertension, or diabetes mellitus.

Conclusions

High maternal body mass index during pregnancy and maternal height are previously undescribed predictors of offspring AF. Efforts to prevent maternal obesity might reduce later AF in offspring. Birth weight has a U‐shaped relation to incident AF independent of other perinatal variables.

Relationships of Measured and Genetically Determined Height With the Cardiac Conduction System in Healthy Adults

Background—

Increasing height is an independent risk factor for atrial fibrillation, but the underlying mechanisms are unknown. We hypothesized that height-related differences in electric conduction could be potential mediators of this relationship.

Methods and Results—

We enrolled 2149 adults aged 25 to 41 years from the general population. Height was directly measured, and a resting 12-lead ECG obtained under standardized conditions. Multivariable linear regression models were used to evaluate the association between measured height and ECG parameters. Mendelian randomization analyses were then performed using 655 independent height-associated genetic variants previously identified in the GIANT consortium. Median age was 37 years, and median height was 1.71 m. Median PR interval, QRS duration, and QTc interval were 156, 88, and 402 ms, respectively. After multivariable adjustment, β-coefficients (95% confidence intervals) per 10 cm increase in measured height were 4.17 (2.65–5.69; P <0.0001) for PR interval and 2.06 (1.54–2.58; P <0.0001) for QRS duration. Height was not associated with QTc interval or the Sokolow–Lyon index. An increase of 10 cm in genetically determined height was associated with increases of 4.33 ms (0.76–7.96; P =0.02) in PR interval and 2.57 ms (1.33–3.83; P <0.0001) in QRS duration but was not related to QTc interval or Sokolow–Lyon index.

Conclusions—

In this large population-based study, we found significant associations of measured and genetically determined height with PR interval and QRS duration. Our findings suggest that adult height is a marker of altered cardiac conduction and that these relationships may be causal.

Traditional Cardiovascular Risk Factors for Incident Atrial Fibrillation

To prevent atrial fibrillation (AF), it is essential to reduce its risk factors and extend healthy life expectancy as a result. There are few reviews on the AF risk factors. We discuss them and approach the prevention of AF. We briefly review traditional risk factors for incident AF, especially focusing on high blood pressure, overweight/obesity, dyslipidemia, diabetes, tobacco smoking, and excessive drinking. When trying to prevent AF by modifying lifestyle, it is important to comprehensively utilize the risk factors for AF to predict the 10-year as an AF risk score. However, there are only 2 risk scores of AF just for the US population. There are few studies of the AF risk factors in non-Western populations. A risk score for incident AF in non-Westerners is awaited because different race and lifestyles may have different contributions as AF risk factors. An AF risk score in accordance with race could be useful for identifying persons with a high risk of AF in order to encourage them to consult a doctor and encourage lifestyle modifications before the onset of AF. (Circ J 2016; 80: 2415-2422).

Association between Birth Characteristics and Cardiovascular Autonomic Function at Mid-Life

Background

Low birth weight is associated with an increased risk of cardiovascular diseases in adulthood. As abnormal cardiac autonomic function is a common feature in cardiovascular diseases, we tested the hypothesis that low birth weight may also be associated with poorer cardiac autonomic function in middle-aged subjects.

Methods

At the age of 46, the subjects of the Northern Finland Birth Cohort 1966 were invited to examinations including questionnaires about health status and life style and measurement of vagally-mediated heart rate variability (rMSSD) from R-R intervals (RRi) and spontaneous baroreflex sensitivity (BRS) in both seated and standing positions. Maternal parameters had been collected in 1965–1966 since the 16^th gestational week and birth variables immediately after delivery. For rMSSD, 1,799 men and 2,279 women without cardiorespiratory diseases and diabetes were included and 902 men and 1,020 women for BRS. The analyses were adjusted for maternal (age, anthropometry, socioeconomics, parity, gestational smoking) and adult variables (life style, anthropometry, blood pressure, glycemic and lipid status) potentially confounding the relationship between birth weight and autonomic function.

Results

In men, birth weight correlated negatively with seated (r = -0.058, p = 0.014) and standing rMSSD (r = -0.090, p<0.001), as well as with standing BRS (r = -0.092, p = 0.006). These observations were verified using relevant birth weight categories (<2,500 g; 2,500–3,999 g; ≥4,000 g). In women, birth weight was positively correlated with seated BRS (r = 0.081, p = 0.010), but none of the other measures of cardiovascular autonomic function. These correlations remained significant after adjustment for potential confounders (p<0.05 for all).

Conclusions

In men, higher birth weight was independently associated with poorer cardiac autonomic function at mid-life. Same association was not observed in women. Our findings suggest that higher, not lower, birth weight in males may contribute to less favourable cardiovascular autonomic regulation and potentially to an elevated cardiovascular risk in later life.

The interrelationships of birthweight, inflammation and body composition in healthy adults

BACKGROUND

Lower birthweight is associated with an increased risk of cardiovascular diseases and diabetes. We hypothesized that inflammation and body fat may be potential mediators for these inverse relationships.

MATERIALS AND METHODS

Healthy adults aged 25-41 years were enrolled in a prospective population-based cohort study in the Principality of Liechtenstein. Main exclusion criteria were diabetes, overt cardiovascular disease or a body mass index > 35 kg/m(2) . Birthweight was self-reported by the study participants. White blood cell (WBC) count and high-sensitivity C-reactive protein (hs-CRP) levels were assayed from fresh blood samples. Body composition was determined by bioelectrical impedance analysis. Multivariable linear regression models were constructed to assess the relationships between birthweight, inflammation and body composition.

RESULTS

Our sample consisted of 1774 participants (53·4% females) with a median age of 37 years. Median birthweight was 3355 g. In multivariable models, we found an inverse relationship of birthweight with hs-CRP levels (β -0·010 (95% CI -0·02; -0·002), P = 0·01) and WBC count (β -0·002 (95% CI -0·004; -0·0002), P = 0·03). Additional adjustment for body fat mass attenuated these relationships (β -0·008 (95% CI -0·02; 0·0003), P = 0·06 for hs-CRP levels and (β -0·002 (95% CI -0·004; 0·0006), P = 0·16 for WBC count. Body fat mass itself was strongly associated with birthweight (β -0·06 (95% CI -0·10; -0·03), P < 0·0001).

CONCLUSION

Birthweight is inversely associated with inflammation in adulthood. This relationship may be mediated by an elevated body fat mass among individuals with lower birthweight.

Maternal protein-energy malnutrition during early pregnancy in sheep impacts the fetal ornithine cycle to reduce fetal kidney microvascular development

This paper identifies a common nutritional pathway relating maternal through to fetal protein-energy malnutrition (PEM) and compromised fetal kidney development. Thirty-one twin-bearing sheep were fed either a control (n=15) or low-protein diet (n=16, 17 vs. 8.7 g crude protein/MJ metabolizable energy) from d 0 to 65 gestation (term, ∼145 d). Effects on the maternal and fetal nutritional environment were characterized by sampling blood and amniotic fluid. Kidney development was characterized by histology, immunohistochemistry, vascular corrosion casts, and molecular biology. PEM had little measureable effect on maternal and fetal macronutrient balance (glucose, total protein, total amino acids, and lactate were unaffected) or on fetal growth. PEM decreased maternal and fetal urea concentration, which blunted fetal ornithine availability and affected fetal hepatic polyamine production. For the first time in a large animal model, we associated these nutritional effects with reduced micro- but not macrovascular development in the fetal kidney. Maternal PEM specifically impacts the fetal ornithine cycle, affecting cellular polyamine metabolism and microvascular development of the fetal kidney, effects that likely underpin programming of kidney development and function by a maternal low protein diet.—Dunford, L. J., Sinclair, K. D., Kwong, W. Y., Sturrock, C., Clifford, B. L., Giles, T. C., Gardner, D. S.. Maternal protein-energy malnutrition during early pregnancy in sheep impacts the fetal ornithine cycle to reduce fetal kidney microvascular development.

Genetic variants related to height and risk of atrial fibrillation: the cardiovascular health study

Increased height is a known independent risk factor for atrial fibrillation (AF). However, whether genetic determinants of height influence risk is uncertain. In this candidate gene study, we examined the association of 209 height-associated single-nucleotide polymorphisms (SNPs) with incident AF in 3,309 persons of European descent from the Cardiovascular Health Study, a prospective cohort study of older adults (aged ≥ 65 years) enrolled in 1989-1990. After a median follow-up period of 13.2 years, 879 participants developed incident AF. The height-associated SNPs together explained approximately 10% of the variation in height (P = 6.0 × 10(-8)). Using an unweighted genetic height score, we found a nonsignificant association with risk of AF (per allele, hazard ratio = 1.01, 95% confidence interval: 1.00, 1.02; P = 0.06). In weighted analyses, we found that genetically predicted height was strongly associated with AF risk (per 10 cm, hazard ratio = 1.30, 95% confidence interval: 1.03, 1.64; P = 0.03). Importantly, for all models, the inclusion of actual height completely attenuated the genetic height effect. Finally, we identified 1 nonsynonymous SNP (rs1046934) that was independently associated with AF and may warrant future study. In conclusion, we found that genetic determinants of height appear to increase the risk of AF, primarily via height itself. This approach of examining SNPs associated with an intermediate phenotype should be considered as a method for identifying novel genetic targets.

Body fat, body fat distribution, lean body mass and atrial fibrillation and flutter. A Danish cohort study

OBJECTIVE

It is recognized that higher height and weight are associated with higher risk of atrial fibrillation or flutter (AF) but it is unclear whether risk of AF is related to body fat, body fat location, or lean body mass.

METHODS

This article reports the Danish population-based prospective cohort Diet, Cancer and Health study conducted among 55,273 men and women 50-64 years of age at recruitment. The associations between bioelectrical impedance derived measures of body composition and combinations of anthropometric measures of body fat distribution and risk of an incident record of AF in the Danish Registry of Patients were investigated.

RESULTS

During follow-up (median 13.5 years) AF developed in 1,669 men and 912 women. Higher body fat at any measured location was associated with higher risk of AF. The adjusted hazard ratio (HR) per 1 sex-specific standard deviation (SD) increment in body fat mass was 1.29 (95% confidence interval [CI], 1.24-1.33). Higher lean body mass was also associated with a higher risk of AF. The adjusted HR for 1 sex-specific SD increment was 1.40 (95% CI, 1.35-1.45).

CONCLUSION

Higher body fat and higher lean body mass were both associated with higher risk of AF.

Birth weight and the risk of atrial fibrillation in whites and African Americans: the Atherosclerosis Risk In Communities (ARIC) study

BACKGROUND

Low birth weight (LBW) has been associated with an increased risk of cardiovascular disease (CVD). A previous study, however, found higher risk of atrial fibrillation (AF) in individuals with higher birth weight (BW). To further understand this apparent paradox, we examined the relationship between AF and BW in the Atherosclerosis Risk in Communities (ARIC) cohort.

METHODS

The analysis included 10,132 individuals free of AF at baseline (1996-1998), who provided BW information, were not born premature, and were not a twin. Self-reported BW was categorized as low (<2.5 kg), medium (2.5-4 kg), and high (>4.0 kg). AF incidence was ascertained from hospital discharge codes and death certificates. We used multivariable Cox proportional hazard models to determine the hazard ratios (HR) and 95% confidence intervals (CI) of AF across BW groups.

RESULTS

During an average follow-up of 10.3 years, we identified 882 incident AF cases. LBW was associated with higher risk of AF. Compared to individuals in the medium BW category, the HR (95% CI) of AF was 1.33 (0.99, 1.78) for LBW and 1.00 (0.81, 1.24) for high BW after adjusting for sociodemographic variables (p for trend = 0.29). Additional adjustment for CVD risk factors did not attenuate the associations (HR 1.42, 95% CI 1.06, 1.90 for LBW and HR 0.86, 95% CI 0.69-1.07 for high BW, compared to medium BW, p for trend = 0.01).

CONCLUSION

LBW was associated with a higher risk of AF. This association was independent of known predictors of AF and is consistent with that observed for other cardiovascular diseases.

Birth weight and carotid artery intima-media thickness

OBJECTIVES

To determine the association between birth weight and carotid artery intima-media thickness (CIMT), a measure of atherogenesis, in a population of 11-year-old children.

STUDY DESIGN

CIMT measured by high-resolution ultrasound, and birth registry data were available for 670 children of the Southern California Children's Health Study. Multivariate regression analyses were performed to investigate the association between birth weight and CIMT, with adjustment for child's health status and lifestyle, pregnancy information, and parental health.

RESULTS

Mean CIMT was 0.57 mm (SD 0.04). We found a nonlinear association between birth weight and CIMT, with an increase in CIMT of 0.014 mm in the fifth (P value .01) compared with the third birth weight quintile. These associations were robust in subsample analyses in children considered normal-weight by gestational age or in term-born children. No significant association with CIMT was found for the lowest quintile.

CONCLUSIONS

Greater birth weight was significantly associated with increased CIMT at age 11 years. No evidence for an impact of lower birth weight was found. The predictive value of childhood CIMT on future cardiovascular outcomes is largely unknown, but strong associations between childhood cardiovascular disease risk factors and adult vascular disease suggest that increased CIMT in childhood may be clinically important.

Early life predictors of atrial fibrillation-related mortality: evidence from the health and retirement study

Prior research found that Americans born in 6 southeastern states (the AF-risk zone) had elevated risk of AF-related mortality, but no mechanisms were identified. We hypothesized the association between AF-related mortality and AF-risk zone birth is explained by indicators of childhood social disadvantage or adult risk factors. In 24,323 participants in the US Health and Retirement Study, we found that birth in the AF-risk zone was significantly associated with hazard of AF-related mortality. Among whites, the relationship was specific to place of birth, rather than place of adult residence. Neither paternal education nor subjectively assessed childhood SES predicted AF-related mortality. Conventional childhood and adult cardiovascular risk factors did not explain the association between place of birth and AF-related mortality.

Risk factors for incident atrial fibrillation with and without left atrial enlargement in women

BACKGROUND

Left atrial (LA) enlargement facilitates induction and/or maintenance of atrial fibrillation (AF). However, little is known about risk factors for AF with normal LA size.

METHODS

We prospectively followed 34713 initially healthy women for incident AF. Information on echocardiographic LA size at first AF diagnosis was abstracted from medical charts during AF confirmation. LA enlargement was defined as LA diameter >40 mm. Using a competing risk approach, we constructed Cox proportional-hazards models to calculate hazard ratios (HR) and 95% confidence intervals (CI) of risk factors for incident AF with and without LA enlargement, respectively.

RESULTS

Among 796 women with incident AF and available LA size, 328 (41%) had LA enlargement. In multivariable competing risk models, the relationship between age and incident AF was stronger in those with (HR 1.12, 95% CI 1.10-1.14) versus without (HR 1.08, 95% CI 1.06-1.09) LA enlargement (p for difference <0.0001). Body weight was associated with AF only in the presence of LA enlargement (HR per 10 kg 1.34, 95% CI 1.26-1.43; versus 1.07, 95% CI 0.998-1.14, p for difference<0.0001). Hypertension and height were significantly associated with AF both in the presence (HR 1.99, 95% CI 1.49-2.65; and HR per 10 cm 1.36, 95% CI 1.13-1.63) and absence (1.55, 1.25-1.92 and 1.29, 1.10-1.50) of LA enlargement (p for difference 0.17 and 0.66, respectively).

CONCLUSIONS

These data suggest that LA enlargement explains much of the increased AF risk associated with obesity and age. In contrast, height and hypertension appear to also influence AF risk through other mechanisms besides LA enlargement.

Premature Atrial Contractions in the General Population

Background—

Premature atrial contractions (PACs) are independent predictors of atrial fibrillation, stroke, and death. However, little is known about PAC frequency in the general population and its association with other cardiovascular risk factors.

Methods and Results—

We performed a cross-sectional analysis among participants of the population-based Swiss cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA). 24-hour Holter electrocardiograms to assess PAC prevalence and frequency were performed in a random sample of 1742 participants aged ≥50 years. The median (interquartile range) number of PACs per hour was 0.8 (0.4–1.8), 1.1 (0.5–2.4), 1.4 (0.7–4.6), 2.3 (0.8–6.9), and 2.6 (1.2–6.5) among participants aged 50 to 55, 55 to 60, 60 to 65, 65 to 70, and ≥70 years, respectively ( P <0.0001). Only 18 (1.0%) participants did not have at least 1 PAC during Holter monitoring. In multivariable negative binomial regression models, PAC frequency was significantly associated with age (risk ratio [RR] per SD 1.80; P <0.0001), height (RR per SD 1.52; P <0.0001), prevalent cardiovascular disease (RR 2.40; P <0.0001), log-transformed N-terminal pro B-type natriuretic peptides (RR per SD 1.27; P <0.0001), physical activity ≥2 hours per day (RR 0.69; P =0.002), and high-density lipoprotein cholesterol (RR per SD 0.80; P =0.0002). Hypertension and body mass index were not significantly related to PAC frequency.

Conclusions—

To our knowledge, this is the first study to assess risk factors for PAC frequency in the general population aged ≥50 years. PACs are common, and their frequency is independently associated with age, height, history of cardiovascular disease, natriuretic peptide levels, physical activity, and high-density lipoprotein cholesterol. The underlying mechanisms of these relationships need to be addressed in future studies.

The placental origins of sudden cardiac death

OBJECTIVE

Most sudden cardiac deaths are due to cardiac arrhythmias, and abnormalities in the autonomic nervous system could underlie them. There is growing evidence that coronary heart disease is associated with alterations of fetal development as a result of variations in the processes of placentation that control fetal nutrition. We hypothesized that placental size would be associated with sudden cardiac death.

METHODS

We examined sudden cardiac death within the Helsinki Birth Cohort of 13 345 men and women.

RESULTS

One hundred eighty-seven (2.7%) men and 47 (0.7%) women had sudden unexplained cardiac death outside hospital. Sudden death was associated with a thin placenta, the hazard ratio being 1.47 [95% confidence interval (CI) 1.11-1.93, P = 0.006] for each g/cm(2) decrease in thickness. Sudden death was independently associated with poor educational attainment (P < 0.0001). Both of these associations were independent of socio-economic status in later life.

CONCLUSION

Sudden death may be initiated by impaired development of the autonomic nervous system in utero as a result of shallow invasion of the spiral arteries in the maternal endometrium and consequent fetal malnutrition.

The impact of height on the risk of atrial fibrillation: the Cardiovascular Health Study

AIMS

Atrial fibrillation (AF) is the most common sustained arrhythmia. Increased body size has been associated with AF, but the relationship is not well understood. In this study, we examined the effect of increased height on the risk of AF and explore potential mediators and implications for clinical practice.

METHODS AND RESULTS

We examined data from 5860 individuals taking part in the Cardiovascular Health Study, a cohort study of older US adults followed for a median of 13.6 (women) and 10.3 years (men). Multivariate linear models and age-stratified Cox proportional hazards and risk models were used, with focus on the effect of height on both prevalent and incident AF. Among 684 (22.6%) and 568 (27.1%) incident cases in women and men, respectively, greater height was significantly associated with AF risk [hazard ratio (HR)(women) per 10 cm 1.32, confidence interval (CI) 1.16-1.50, P < 0.0001; HR(men) per 10 cm 1.26, CI 1.11-1.44, P < 0.0001]. The association was such that the incremental risk from sex was completely attenuated by the inclusion of height (for men, HR 1.48, CI 1.32-1.65, without height, and HR 0.94, CI 0.85-1.20, with height included). Inclusion of height in the Framingham model for incident AF improved discrimination. In sequential models, however, we found minimal attenuation of the risk estimates for AF with adjustment for left ventricular (LV) mass and left atrial (LA) dimension. The associations of LA and LV size measurements with AF risk were weakened when indexed to height.

CONCLUSION

Independent from sex, increased height is significantly associated with the risk of AF.

Hypertension and atrial fibrillation: diagnostic approach, prevention and treatment. Position paper of the Working Group 'Hypertension Arrhythmias and Thrombosis' of the European Society of Hypertension

Hypertension is the most common cardiovascular disorder and atrial fibrillation is the most common clinically significant arrhythmia. Both these conditions frequently coexist and their prevalence increases rapidly with aging. There are different risk factors and clinical conditions predisposing to the development of atrial fibrillation, but due its high prevalence, hypertension is still the main risk factor for the development of atrial fibrillation. Several pathophysiologic mechanisms (such as structural changes, neurohormonal activation, fibrosis, atherosclerosis, etc.) have been advocated to explain the onset of atrial fibrillation. The presence of atrial fibrillation per se increases the risk of stroke but its coexistence with high blood pressure leads to an abrupt increase of cardiovascular complications. Different risk models are available for the risk stratification and the prevention of thromboembolism in patients with atrial fibrillation. In all of them hypertension is present and is an important risk factor. Antihypertensive treatment may contribute to reduce this risk, and it seems some classes are superior to others in the prevention of new-onset atrial fibrillation and prevention of stroke. Antithrombotic treatment with warfarin is effective in the prevention of thromboembolic events, although quite recently, new classes of anticoagulants that do not require international normalized ratio monitoring have been introduced with promising results.

Relation of renal function to risk for incident atrial fibrillation in women

Few prospective studies have explored the association between renal function and risk for incident atrial fibrillation (AF) in apparently healthy populations. A total of 24,746 women participating in the Women's Health Study who were free of cardiovascular disease and AF and provided blood samples at baseline were prospectively followed for incident AF from 1993 to 2010. AF events were confirmed by medical chart review. Estimated glomerular filtration rate (eGFR) was calculated from baseline creatinine using the Chronic Kidney Disease Epidemiology (CKD-EPI) equation. Cox models were used to estimate hazard ratios and 95% confidence intervals (CIs) for incident AF across eGFR categories controlling for AF risk factors. During a median of 15.4 years of follow-up, 786 incident AF events occurred. The multivariate-adjusted hazard ratios for incident AF across eGFR categories (<60, 60 to 74.9, 75 to 89, and ≥90 ml/min/1.73 m(2)) were 1.36 (95% CI 1.00 to 1.84), 0.90 (95% CI 0.71 to 1.14), 0.99 (95% CI 0.84 to 1.18) and 1.00, respectively, without evidence of a linear association (P for trend = 0.48). Similarly, there was no significant curvilinear association (quadratic p = 0.10) in multivariate analysis across categories. Compared to women with eGFRs ≥60 ml/min/1.73 m(2), the 1,008 women with eGFRs <60 ml/min/1.73 m(2) had a multivariate-adjusted hazard ratio for AF of 1.39 (95% CI 1.04 to 1.86, p = 0.03). In conclusion, no significant linear or curvilinear relation was observed between incident AF and less severe impairment of renal function in this large prospective cohort of women. However, a significant elevation in AF risk was observed at a threshold eGFR of <60 ml/min/1.73 m(2).

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

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

Circulation: Arrhythmia and Electrophysiology Editors' Picks

The following articles are being highlighted as part of the Circulation: Arrhythmia and Electrophysiology Topic Review series. This series will summarize the most important manuscripts, as selected by the editors, published in Circulation: Arrhythmia and Electrophysiology and the rest of the Circulation portfolio. The studies included in this article represent the most-read articles published on the topic of atrial fibrillation in 2009 and 2010.

Early-life antecedents of atrial fibrillation: place of birth and atrial fibrillation-related mortality

PURPOSE

Recent evidence suggests early-life factors correlate with atrial fibrillation (AF). We hypothesized that AF-related mortality, similar to stroke mortality, is elevated for individuals born in the southeastern United States.

METHODS

We estimated 3-year (1999-2001) average AF-related mortality rates by using U.S. vital statistics for 55- to 89-year-old white (136,573 AF-related deaths) and black subjects (8,288 AF-related deaths). We estimated age- and sex-adjusted odds of AF-related (contributing cause) mortality associated with birth state, and birth within the U.S. stroke belt (SB), stratified by race. SB results were replicated with the use of 1989-1991 data.

RESULTS

Among black subjects, four contiguous birth states were associated with statistically significant odds ratios ≥ 1.25 compared with the national average AF-related mortality. The four highest-risk birth states for blacks also predicted elevated AF-related mortality among white subjects, but patterns were attenuated. The odds ratio for AF-related mortality associated with SB birth was 1.19 (confidence interval 1.13-1.25) for black and 1.09 (CI 1.07-1.12) for white subjects when we adjusted for SB adult residence.

CONCLUSIONS

Place of birth predicted AF-related mortality, after we adjusted for place of adult residence. The association of AF-related mortality and SB birth parallels that of other cardiovascular diseases and may likewise indicate an importance of early life factors in the development of AF.

Increased risk of atrial fibrillation in patients with coeliac disease: a nationwide cohort study

AIMS

Inflammatory markers are established risk factors for atrial fibrillation (AF), but the role of autoimmune diseases is unknown. The aim of the study was to examine the association between coeliac disease (CD) and AF in a large cohort of patients with biopsy-verified CD.

METHODS AND RESULTS

We identified 28,637 patients with CD through biopsy reports (defined as Marsh 3: villous atrophy) from all pathology departments (n = 28) in Sweden. Biopsies had been performed between 1969 and 2008. Age- and sex-matched reference individuals (n = 141,731) were identified from the Swedish Total Population Register. Data on AF were obtained from the Swedish Hospital Discharge Register, the Hospital Outpatient Register, and the Cause of Death Register. Hazard ratios (HRs) for AF were estimated using Cox regression. In the CD cohort, 941 individuals developed AF (vs. 2918 reference individuals) during a median follow-up of 9 years. The corresponding adjusted HR for AF was 1.34 (95% CI = 1.24-1.44). The absolute risk of AF in CD was 321 of 100,000 person-years, with an excess risk of 81 of 100,000. A prior AF diagnosis was also associated with an increased risk of subsequent CD (odds ratio = 1.45, 95% CI = 1.31-1.62).

CONCLUSIONS

Atrial fibrillation is more common both before and after CD diagnosis in patients with CD though the excess risk is small. Potential explanations for the increased risk of AF in CD include chronic inflammation and shared risk factors, but ascertainment bias may also have contributed.

CLINICAL IMPLICATIONS

Coeliac disease affects 1-2% of the Western population. Our results indicate that patients with coeliac disease, verified by intestinal biopsy, are at increased risk of atrial fibrillation. This observation is consistent with previous findings that elevation of inflammatory markers predicts atrial fibrillation. Additional studies are needed to clarify the mechanistic link between atrial fibrillation and autoimmune diseases such as coeliac disease.