Resting heart rate and physical activity as risk factors for lone atrial fibrillation: a prospective study of 309 540 men and women

Histological evaluation of cardiac remodelling in equine athletes

Approximately 1-2 per 100,000 young athletes die from sudden cardiac death (SCD) and extreme exercise may be associated with myocardial scar and arrhythmias. Racehorses have a high prevalence of atrial fibrillation (AF) and SCD but the presence of myocardial scar and inflammation has not been evaluated. Cardiac tissues from the left (LAA) and right (RAA) atrial appendages, left ventricular anterior (LVAPM) and posterior (LVPPM) papillary muscles, and right side of the interventricular septum (IVS-R) were harvested from racehorses with sudden cardiac death (SCD, n = 16) or other fatal injuries (OFI, n = 17), constituting the athletic group (ATH, n = 33), and compared to sedentary horses (SED, n = 10). Horses in the ATH group had myocyte hypertrophy at all sites; increased fibrosis at all sites other than the LAA; increased fibroblast infiltration but a reduction in the overall extracellular matrix (ECM) volume in the RAA, LVAPM, and IVS-R compared to SED horses. In this horse model, athletic conditioning was associated with myocyte hypertrophy and a reduction in ECM. There was an excess of fibrocyte infiltration and focal fibrosis that was not present in non-athletic horses, raising the possibility of an exercise-induced pro-fibrotic substrate.

Reference ranges for ambulatory heart rate measurements in a middle-aged population

BACKGROUND

Elevated heart rate (HR) predicts cardiovascular disease and mortality, but there are no established normal limits for ambulatory HR. We used data from the Swedish CArdioPulmonary Imaging Study to determine reference ranges for ambulatory HR in a middle-aged population. We also studied clinical correlates of ambulatory HR.

METHODS

A 24-hour ECG was registered in 5809 atrial fibrillation-free individuals, aged 50-65 years. A healthy subset (n=3942) was used to establish reference values (excluding persons with beta-blockers, cardiovascular disease, hypertension, heart failure, anaemia, diabetes, sleep apnoea or chronic obstructive pulmonary disease).Minimum HR was defined as the lowest 1-minute HR. Reference ranges are reported as means±SDs and 2.5th-97.5th percentiles. Clinical correlates of ambulatory HR were analysed with multivariable linear regression.

RESULTS

The average mean and minimum HRs were 73±9 and 48±7 beats per minute (bpm) in men and 76±8 and 51±7 bpm in women; the reference range for mean ambulatory HR was 57-90 bpm in men and 61-92 bpm in women. Average daytime and night-time HRs are also reported. Clinical correlates, including age, sex, height, body mass index, physical activity, smoking, alcohol intake, diabetes, hypertension, haemoglobin level, use of beta-blockers, estimated glomerular filtration rate, per cent of predicted forced expiratory volume in 1 s and coronary artery calcium score, explained <15% of the interindividual differences in HR.

CONCLUSION

Ambulatory HR varies widely in healthy middle-aged individuals, a finding with relevance for the management of patients with a perception of tachycardia. Differences in ambulatory HR between individuals are largely independent of common clinical correlates.

Heart Rate at Rest and Incident Atrial Fibrillation in Patients With Diastolic Dysfunction

Diastolic dysfunction (DD) is associated with incident atrial fibrillation (AF). The influence of heart rate at rest (RHR) on incident AF in patients with DD has not been investigated. The goal of this study is to assess the influence of RHR on incident AF in patients with DD. Patients from a large health system with no previous history of AF, a left ventricular ejection fraction ≥50%, and documented DD on echocardiography were divided into quartiles (<66, 66 to 76, 77 to 91, >91 beats per minute) based on RHR. Incident AF was estimated using AF hospitalization during follow-up. Hazard ratios (HR) for AF hospitalization and all-cause death were calculated with a Cox proportional hazards model. A total of 19,046 patients were analyzed. Over a median follow-up of 42.2 months, 742 (3.9%) patients were hospitalized for AF. Both slower and faster RHR were associated with increased risk of AF hospitalization (HR 1.40, confidence interval [CI] 1.14 to 1.71, p = 0.001, HR 1.23, CI 0.99 to 1.53, p = 0.06 and HR 1.72, CI 1.38 to 2.14, p <0.001, for quartiles 1, 2, and 4, respectively), suggesting a J-shaped relation. Progressive increase in all-cause death was noted with faster RHR (HR1.19 per quartile increase, CI 1.16 to 1.22, p <0.001). These results persisted after adjustment for age, cardiovascular co-morbidities, grade of DD, and β-blocker use. In conclusion, this large, real-world analysis indicates increased risk of incident AF with slower and faster RHR in patients with DD. Randomized trials are needed to evaluate the potential of RHR modification to mitigate the risk of incident AF.

Vigorous physical activity and atrial fibrillation in healthy individuals: What is the correct approach?

Sport activity compared to sedentary life is associated with improved wellbeing and risk reduction in many different health conditions including atrial fibrillation (AF). Vigorous physical activity is associated with increased AF risk. We describe four individuals, who regularly perform endurance sport activity and developed AF. We discuss the changes occurring in the heart of endurance athletes and the possible etiology for AF, as well as currently available treatment options in this seemingly healthy population. Although the etiology of AF in the general population differs from the one in the usually younger endurance sport activity population, the treatment options are similar. There are several factors unique to those involved in vigorous physical activity that can influence their management. Despite a lack of evidence, endurance athletes with AF have traditionally been advised to "de-training," to reduce both the amount and intensity of exercise. Some of the current offered treatment options (beta-blockers, class III antiarrhythmic) have a varied range of adverse effect, hindering them unattractive for these individuals. Depending on risk stratification tools, anticoagulation may be indicated. Some suggest an intermittent dosing therapy, while others recommend following current guidelines. AF ablation is recommended in exercising individuals with recurrent, symptomatic AF and/or in those who do not want drug therapy, given its impact on athletic performance, AF treatment decisions should be individualized for those engaging vigorous physical activity, while considering the potential risks, the urgency of returning to training, and the will and expectations of the patient.

Elite female endurance athletes are at increased risk of atrial fibrillation compared to the general population: a matched cohort study

OBJECTIVE

Previous studies have found that endurance sport activity is associated with an increased risk of atrial fibrillation (AF) in men. However, it remains unclear whether endurance sports also influence the risk of AF in women. We aimed to examine whether participation in endurance sports may affect the risk of AF in female athletes.

METHODS

We conducted a retrospective matched cohort study of top Swedish female endurance athletes (n=228) and reference individuals (n=1368) from the general population using the Swedish Total Population Register individually matched with a 6:1 ratio of female athletes. The athlete cohort was created by combining all Swedish women who ran the Stockholm Marathon faster than 3 hours 15 min in any of the races between 1979 and 1991, all women competing in the Swedish athletic national championships in the 10 000 metre race, and the top-ranked Swedish cyclists during the same period. We used the National Patient Register to determine whether the participants were diagnosed with AF.

RESULTS

Mean age at the start of follow-up was 32 (SD±8.5) years. During follow-up (mean 28.8 years; SD±4.4), 33 cases of AF were diagnosed, including 10 (4.4%) among athletes and 23 (1.7%) among references. The HR for female athletes compared with the reference population was 2.56 (95% CI 1.22 to 5.37) in the univariable model and 3.67 (95% CI 1.71 to 7.87) after adjustment for hypertension.

CONCLUSION

Elite female endurance athletes are at increased risk of AF than the general population.

Genetic insights into resting heart rate and its role in cardiovascular disease

Resting heart rate is associated with cardiovascular diseases and mortality in observational and Mendelian randomization studies. The aims of this study are to extend the number of resting heart rate associated genetic variants and to obtain further insights in resting heart rate biology and its clinical consequences. A genome-wide meta-analysis of 100 studies in up to 835,465 individuals reveals 493 independent genetic variants in 352 loci, including 68 genetic variants outside previously identified resting heart rate associated loci. We prioritize 670 genes and in silico annotations point to their enrichment in cardiomyocytes and provide insights in their ECG signature. Two-sample Mendelian randomization analyses indicate that higher genetically predicted resting heart rate increases risk of dilated cardiomyopathy, but decreases risk of developing atrial fibrillation, ischemic stroke, and cardio-embolic stroke. We do not find evidence for a linear or non-linear genetic association between resting heart rate and all-cause mortality in contrast to our previous Mendelian randomization study. Systematic alteration of key differences between the current and previous Mendelian randomization study indicates that the most likely cause of the discrepancy between these studies arises from false positive findings in previous one-sample MR analyses caused by weak-instrument bias at lower P-value thresholds. The results extend our understanding of resting heart rate biology and give additional insights in its role in cardiovascular disease development.

Blood pressure, hypertension and the risk of atrial fibrillation: a systematic review and meta-analysis of cohort studies

Elevated blood pressure and hypertension have been associated with increased risk of atrial fibrillation in a number of epidemiological studies, however, the strength of the association has differed between studies. We conducted a systematic review and meta-analysis of the association between blood pressure and hypertension and atrial fibrillation. PubMed and Embase databases were searched for studies of hypertension and blood pressure and atrial fibrillation up to June 6th 2022. Cohort studies reporting adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) of atrial fibrillation associated with hypertension or blood pressure were included. A random effects model was used to estimate summary RRs. Sixty eight cohort studies were included in the meta-analysis. The summary RR was 1.50 (95% CI: 1.42-1.58, I2 = 98.1%, n = 56 studies) for people with hypertension compared to those without hypertension (1,080,611 cases, 30,539,230 participants), 1.18 (95% CI: 1.16-1.21, I2 = 65.9%, n = 37 studies) per 20 mmHg increase in systolic blood pressure (346,471 cases, 14,569,396 participants), and 1.07 (95% CI: 1.03-1.11, I2 = 91.5%, n = 22 studies) per 10 mmHg increase in diastolic blood pressure (332,867 cases, 14,354,980 participants). There was evidence of a nonlinear association between diastolic blood pressure and atrial fibrillation with a steeper increase in risk at lower levels of diastolic blood pressure, but for systolic blood pressure the association appeared to be linear. For both systolic and diastolic blood pressure, the risk increased even within the normal range of blood pressure and persons at the high end of systolic and diastolic blood pressure around 180/110 mmHg had a 1.8-2.3 fold higher risk of atrial fibrillation compared to those with a blood pressure of 90/60 mmHg. These results suggest that elevated blood pressure and hypertension increases the risk of atrial fibrillation and there is some increase in risk even within the normal range of systolic and diastolic blood pressure.

Weekly physical activity and incident atrial fibrillation in females - A dose-response meta-analysis

BACKGROUND

For years, physical activity (PA) has been considered a mixed blessing in terms of the risk of incident atrial fibrillation (AF). Previous analyses have had equivocal results regarding the cut-off of PA level beyond which AF risk increases, if such a limit really does exist. Data regarding females in particular have been scarce.

METHODS

We performed a dose-response meta-analysis to investigate the relationship between weekly PA and the risk for AF in females. Major electronic databases were searched for studies assessing the association between leisure time PA and the risk for incident AF in females from the general population. The linearity of the dose-response curve was assessed using the restricted cubic spline model.

RESULTS

A total of 15 studies, which involved 1,821,422 females, were included in the final analysis. AF incidence was 3.7%. Dose-response analysis revealed an inverse nonlinear relationship between weekly PA and the risk for incident AF (p for linearity <0.0001). No significant heterogeneity was documented (I² = 37%). Cautious interpretation is needed for PA exceeding 50 metabolic equivalents of task- hours per week (METs- h/w), due to limited available data for these high levels of PA.

CONCLUSION

According to this analysis, physicians can safely advise females to perform up to 50METs- h/w of moderate or vigorous PA, to reduce the risk for future AF. Interestingly, significant benefit can be attained even at low levels of regular weekly PA.

May Strenuous Endurance Sports Activity Damage the Cardiovascular System of Healthy Athletes? A Narrative Review

The positive effects of physical activity are countless, not only on the cardiovascular system but on health in general. However, some studies suggest a U-shape relationship between exercise volume and effects on the cardiovascular system. On the basis of this perspective, moderate-dose exercise would be beneficial compared to a sedentary lifestyle, while very high-dose physical activity would paradoxically be detrimental. We reviewed the available evidence on the potential adverse effects of very intense, prolonged exercise on the cardiovascular system, both acute and chronic, in healthy athletes without pre-existing cardiovascular conditions. We found that endurance sports activities may cause reversible electrocardiographic changes, ventricular dysfunction, and troponin elevation with complete recovery within a few days. The theory that repeated bouts of acute stress on the heart may lead to chronic myocardial damage remains to be demonstrated. However, male veteran athletes with a long sports career show an increased prevalence of cardiovascular abnormalities such as electrical conduction delay, atrial fibrillation, myocardial fibrosis, and coronary calcifications compared to non-athletes. It must be underlined that the cause-effect relationship between such abnormalities and the exercise and, most importantly, the prognostic relevance of such findings remains to be established.

Arrhythmogenesis of Sports: Myth or Reality?

Regular exercise confers health benefits with cardiovascular mortality risk reduction through a variety of mechanisms. At a population level, evidence suggests that undertaking more exercise has greater benefits. In the modern era of sport, there has been an exponential rise in professional and amateur athletes participating in endurance events, with a progressively better understanding of the associated cardiac adaptations, collectively termed ‘athletes heart’. However, emerging data raise questions regarding the risk of potential harm from endurance exercise, with an increased risk of arrhythmia from adverse cardiac remodelling. Cross-sectional studies have demonstrated that athletes may exhibit a higher burden of AF, conduction tissue disease, ventricular arrhythmias, a cardiomyopathy-like phenotype and coronary artery disease. In an attempt to separate myth from reality, this review reports on the evidence supporting the notion of ‘too much exercise’, the purported mechanisms of exercise-induced cardiac arrhythmia and complex interplay with sporting discipline, demographics, genetics and acquired factors.

The role of family factors in the association between early adulthood BMI and risk of cardiovascular disease. An intergenerational study of BMI in early adulthood and cardiovascular mortality in parents, aunts and uncles

Background

High body mass index (BMI) in childhood and adolescence is related to cardiovascular disease (CVD). Causality is not established because common genetic or early life socioeconomic factors (family factors) may explain this relationship. We aimed to study the role of family factors in the association between BMI and CVD by investigating if early adulthood BMI in conscripts and CVD mortality in their parents/aunts/uncles are related.

Methods

Data from the Armed Forces Personnel Database (including height and weight among conscripts) were linked with data from the Norwegian Population Registry, generational data from the Norwegian Family Based Life Course Study, the National Educational Registry and the Cause of Death Registry using unique personal identification numbers. The study sample (N=369 464) was Norwegian males born 1967-1993, who could be linked to both parents and at least one maternal and one paternal aunt or uncle. Subsamples were identified as conscripts whose parents/aunts/uncles had data on cardiovascular risk factors available from Norwegian health surveys. Cox proportional hazards regression models were used to estimate hazard ratios (HR) of CVD mortality in the parental generation according to BMI categories of conscripts.

Results

Parents of conscripts with obesity or overweight had a higher hazard of CVD death (fathers HR obese: 1.99 (1.79,2.21), overweight: 1.33 (1.24,1.42) mothers HR obese: 1.65 (1.32,2.07), overweight: 1.23 (1.07,1.42)) than parents of normal- or underweight conscripts. Aunts and uncles of conscripts with obesity and overweight had an elevated hazard of CVD death, but less so than parents. Adjustment for CVD risk factors attenuated the results in parents, aunts and uncles.

Conclusions

Family factors may impact the relationship between early adulthood overweight and CVD in parents. These can be genes with impact on BMI over generations and genes with a pleiotropic effect on both obesity and CVD, as well as shared environment over generations.

Sex-Specific Exposure-Effect Relationship Between Physical Activity and Incident Atrial Fibrillation in the General Population: A Dose-Response Meta-Analysis of 16 Prospective Studies

Background: Since evidence regarding the relationship between physical activity (PA) and atrial fibrillation (AF) incidence is inconsistent among studies, we performed a dose-response meta-analysis to comprehensively evaluate the exposure-effect association between PA and incident AF and the potential sex difference in the general population. Methods: The PubMed and Embase databases were searched for eligible studies published up to July 2020 (PROSPERO: CRD42018091692). The non-linear or linear exposure-effect relationship between PA and AF was examined using the robust error meta-regression method. Results: A total of 16 prospective studies involving 1,449,017 individuals and 39,884 AF cases were included. We observed an inverse non-linear association between PA level and incident AF (I ² = 0%, p _{non-linearity} < 0.001). In the linear model, a 5 metabolic equivalent of task (MET)-h/week increase in PA was associated with a decreased risk of AF [risk ratio (RR) = 0.992, 95% confidence interval (CI): 0.988-0.996, I ² = 0%]. In the sex-stratified analysis, we observed an inverse non-linear relationship between PA level and AF risk in females (I ² = 90%, p _{non-linearity} < 0.0001) but not in males (I ² = 0%, p _{non-linearity} = 0.40). In the linear model, a 5 MET-h/week increase in PA was associated with a reduced risk of AF in females (RR = 0.982, 95% CI: 0.975-0.989, I ² = 71%) but not in males (RR = 0.998, 95% CI: 0.994-1.002, I ² = 0%), with a significant interaction observed between the two groups (p _interaction < 0.0001). Conclusion: There was an inverse non-linear relationship between PA level and incident AF in the general population. The beneficial effect of PA in reducing AF risk might be predominantly observed in females.

Occupational physical activity is associated with risk of atrial fibrillation in both men and women: a population-based cohort study

AIMS

Previous studies have found that excessive sport activities are associated with an increased risk of atrial fibrillation (AF). Whether occupational physical activity (OPA) increases the risk for AF is not well studied. We aimed to examine whether OPA influences the risk of AF.

METHODS

80,922 men and women, free from AF, completed in 1997 a questionnaire about their OPA at that time (baseline), and also retrospectively in 1997 their OPA at the age of 30 and 50 years. Participants were categorised into three groups (low, medium and high) based on OPA load. Participants were followed-up in the Swedish National Patient Register for ascertainment of AF. Cox proportional hazards regression models were used to estimate relative risks (RR) with 95% confidence intervals (CI), adjusted for potential confounders.

RESULTS

11,614 cases of AF were diagnosed during follow-up time of up to 17 years. We observed an increased risk of AF in relation to increased load of OPA regardless of age. Compared with men who reported a low load of OPA, the multivariable RR (95% CI) for men with a high load was 1.10 (1.03-1.17) at 30 years, 1.11 (1.04-1.17) at 50 years and 1.19 (1.10-1.29) at baseline. The results for women were similar with multivariable RR of 1.16 (1.06-1.27) at 30 years, 1.14 (1.05-1.24) at 50 years and 1.11 (0.99-1.24) at baseline.

CONCLUSION

These findings suggest that high load of OPA previous in life may play a role in increasing the risk for AF in both men and women.

Exercising immune cells: The immunomodulatory role of exercise on atrial fibrillation

Exercise training is generally beneficial for cardiovascular health, improving stroke volume, cardiac output, and aerobic capacity. Despite these benefits, some evidence indicates that endurance training may increase the risk of atrial fibrillation (AF), particularly in highly trained individuals. Among multiple mechanisms, autonomic tone changes and atrial remodeling have been proposed as main contributors for exercise-induced AF. However, the contribution of local and systemic immunity is poorly understood in the development of atrial arrhythmogenic substrates. Here we aim to update the field of immunomodulation in the context of exercise and AF by compiling and reconciling the most recent evidence from preclinical and human studies and rationalize the applicability of "lone" AF terminology in athletes.

Can too much exercise be dangerous: what can we learn from the athlete's heart?

Exercise prevents and aids treatment of coronary heart disease, hypertension, heart failure, diabetes mellitus, obesity and depression, reduces cardiac events and improves survival. However, evidence suggests that the relationship between exercise and mortality may be curvilinear, with modest additional benefit at higher levels. Intensive exercise has also been associated with increased atrial fibrillation risk, although its clinical implications are not well understood. Other proposed adverse effects of exercise on the heart, including reduced right ventricular function, elevated cardiac biomarkers, myocardial fibrosis and coronary artery calcification, are less substantiated. Current evidence cannot affirm that extreme exercise is dangerous and future studies should combine large cohorts to obtain a statistically reliable limit. Associations between features of the athlete's heart and cardiovascular morbidity and mortality should also be explored.

Exercise and Athletic Activity in Atrial Fibrillation

Moderate-intensity exercise improves cardiovascular outcomes. However, mounting clinical evidence demonstrates that long-term, high-intensity endurance training predisposes male and veteran athletes to an increased risk of atrial fibrillation (AF), a risk that is not observed across both genders. Although increased mortality associated with AF in the general population is not shared by athletes, clinically significant morbidities exist (eg, reduced exercise capacity, athletic performance, and quality of life). Additional research is needed to fill current gaps in knowledge pertaining to the natural history, pathophysiologic mechanisms, and management strategies of AF in the athlete.

Physical activity and risk of atrial fibrillation in the general population: meta-analysis of 23 cohort studies involving about 2 million participants

Regular physical activity is well established to be associated with reduced risk of cardiovascular disease outcomes. Whether physical activity is associated with the future risk of atrial fibrillation (AF) remains a controversy. Using a systematic review and meta-analysis of published observational cohort studies in general populations with at least one-year of follow-up, we aimed to evaluate the association between regular physical activity and the risk of AF. Relevant studies were sought from inception until October 2020 in MEDLINE, Embase, Web of Science, and manual search of relevant articles. Extracted relative risks (RRs) with 95% confidence intervals (CIs) for the maximum versus the minimal amount of physical activity groups were pooled using random-effects meta-analysis. Quality of the evidence was assessed by GRADE. A total of 23 unique observational cohort studies comprising of 1,930,725 participants and 45,839 AF cases were eligible. The pooled multivariable-adjusted RR (95% CI) for AF comparing the most physically active versus the least physically active groups was 0.99 (0.93–1.05). This association was modified by sex: an increased risk was observed in men: 1.20 (1.02–1.42), with a decreased risk in women: 0.91 (0.84–0.99). The quality of the evidence ranged from low to moderate. Pooled observational cohort studies suggest that the absence of associations reported between regular physical activity and AF risk in previous general population studies and their aggregate analyses could be driven by a sex-specific difference in the associations – an increased risk in men and a decreased risk in women.

Systematic review registration: PROSPERO 2020: CRD42020172814

High fitness might be associated with the development of new-onset atrial fibrillation in obese non-athletic adults

BACKGROUND

Data on the association between AF and fitness are conflicting.

OBJECTIVES

The aim of this analysis was to investigate the association between fitness, obesity and incidence of atrial fibrillation (AF) among apparently healthy non-athlete adults.

METHODS

We investigated 20 410 self-referred subjects who were annually screened in a tertiary medical centre. All subjects were free of AF and completed maximal exercise stress test according to the Bruce protocol at baseline. Fitness was categorised into age- and sex-specific quintiles (Q) according to the treadmill time. Subjects were categorised to low (Q1-Q2) and high fitness (Q3-5) groups. The primary end point was new-onset AF during follow-up.

RESULTS

Mean age was 48 ± 10 years and 72% were men. A total of 463 (2.3%) events occurred during an average follow-up of 8 ± 5 years corresponding to an AF event rate of 0.3% per person year. Univariate and multivariate models showed that AF risk was similar in both fitness groups. However, AF event rate was 0.55% per person year among high fitness obese subjects, compared with 0.31% for low fitness obese subjects (P < .01). Subgroup interaction analysis showed that AF risk is obesity-dependent, such that in the obese group (≥30 kg/m² ) high fitness was independently associated with a significant 79% increased AF risk (95% CI 1.15-2.78; P = .01), whereas among non-obese subjects the rate of events was similar between both fitness groups (P for interaction = (.02)).

CONCLUSIONS

Our findings suggest that high fitness might be associated with increased AF risk among obese subjects.

Examining the lower range of the association between alcohol intake and risk of incident hospitalization with atrial fibrillation

Background

Evidence is sparse on the association between alcohol intakes in the lower range and risk of atrial fibrillation (AF). We aimed to investigate self-reported low and moderate alcohol intakes and subsequent risk of incident AF among current drinkers.

Methods

Norwegian population-based health examination surveys assessing self-reported daily alcohol intake (mean grams per day) were linked to health and population registers. Hazard ratios (HR) (95% confidence interval) for time to incident (first) hospitalization with AF by alcohol intake level were assessed by Cox regression, with adjustment for educational level and cardiovascular risk factors except blood pressure.

Results

The study population included 234,392 participants (49% men). Incident hospitalization with AF was identified in 5043 (2.2%) persons during a mean follow-up of 9 years. Compared to a very low alcohol intake of <1 unit weekly, a moderate consumption in the range of 1 to <2 units daily increased the risk of incident AF by 18% (HR 1.18 [1.06-1.32]). The average risk of incident AF increased by 9% per daily alcohol unit of 12 g (HR 1.09 [1.03, 1.14]). In sex-stratified analyses significant associations were found in men only.

Conclusions

We found that less than two alcohol units/day significantly increased the risk of incident AF, however, in men only. Reduction of even a moderate alcohol intake may thus reduce the risk of AF at the population level.

Objectively Measured Physical Activity and the Risk of Atrial Fibrillation (from the REGARDS Study)

The association between objectively measured physical activity and atrial fibrillation (AF) has not been examined. Therefore, we examined the association between moderate and vigorous physical activity (MVPA) with incident AF in 5,147 participants who completed accelerometer assessment for 4 to 7 consecutive days in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study. MVPA was defined as >1,065 counts/minute, and daily mean time spent in MVPA was computed. Incident AF was identified during follow-up by a study-scheduled electrocardiogram and also from self-reported medical history of a physician diagnosis. Logistic regression was used to assess the relation between daily time in MVPA and incident AF. A total of 429 (8.3%) incident AF cases were detected after a median follow-up of 3.5 years following accelerometer assessment. Participants with higher daily time spent in MVPA were less likely to develop AF than those with lower MVPA achievement (Quartile 1 = 12.4%; Quartile 2 = 8.3%; Quartile 3 = 7.1%; Quartile 4 = 5.4%; p-trend <0.001). In a multivariable model adjusted for AF risk factors, the risk of AF decreased with higher levels of daily MVPA (Quartile 1: Ref; Quartile 2: hazard ratio [HR] = 0.77, 95% confidence interval [CI] 0.58 to 1.01; Quartile 3: HR = 0.72, 95% CI 0.53 to 0.98; Quartile 4: HR = 0.62, 95% CI 0.44 to 0.87; p-trend = 0.0056). In conclusion, higher levels of objectively measured daily MVPA are protective against the development of AF suggesting that promotion of MVPA should be encouraged to reduce the risk of AF.

Efficacy of Physical Exercise on the Quality of Life, Exercise Ability, and Cardiopulmonary Fitness of Patients With Atrial Fibrillation: A Systematic Review and Meta-Analysis

Objective: Physical exercise is recommended to help prevent lifestyle diseases. The present study was designed to quantify the efficacy of physical exercise on the quality of life (QoL), exercise ability and cardiopulmonary fitness of patients with atrial fibrillation (AF).

Method: A comprehensive systematic literature search was performed in Medline, Embase, Cochrane Library, Web of Science and PubMed databases (from 1970 to December 1st, 2019) for randomized controlled trials (RCTs) comparing physical exercise combined with AF routine treatments to routine treatments alone. The meta-analysis was conducted following PRISMA guidelines. Our main outcomes were QoL (measured by the Short-Form 36 scale, SF-36), exercise ability (measured by the 6-min walk test, 6MWT) and cardiopulmonary fitness (measured by peak oxygen uptake and resting heart rate). Quality assessments were conducted using the Cochrane Collaboration tool.

Results: Twelve trials involving 819 patients met the criteria for analysis. The results showed that physical exercise improved the QoL by enhancing physical functioning [standardized mean difference (SMD) = 0.63, 95%CI: 0.18–1.09; p = 0.006], general health perceptions (SMD = 0.64, 95%CI: 0.35–0.93; p < 0.001) and vitality (SMD = 0.51, 95%CI: 0.31–0.71; p < 0.001); increased exercise ability by improving the 6MWT performance (SMD = 0.69, 95%CI: 0.19–1.119; p = 0.007); and enhanced peak VO₂ (SMD = 0.37, 95%CI: 0.16–0.57; p < 0.001) while reducing resting heart rate (SMD = −0.39, 95%CI: −0.65 to −0.13; p = 0.004). In addition, meta-regression analysis showed that training mode (p_{physicalfunctioning} = 0.012, p_{generalhealthperceptions} = 0.035) and training duration (p = 0.047) were the main factors of an intervention that influenced the effect size. Following sub-group analysis, we found that aerobics, Yoga and longer training durations (≥60 min) showed larger improvements.

Conclusion: In summary, our meta-analysis shows that physical exercise has a positive effect on the QoL, exercise ability and cardiopulmonary fitness in AF patients. When physicians offer exercise recommendations to AF patients, they should consider both the training mode and training duration to achieve maximum results.

Impact of endurance exercise on the heart of cyclists: A systematic review and meta-analysis

OBJECTIVE

To compare heart structure and function in endurance athletes relative to participants of other sports and non-athletic controls in units relative to body size. A secondary objective was to assess the association between endurance cycling and cardiac abnormalities.

PATIENTS AND METHODS

Five electronic databases (CINAHL, Cochrane Library, Medline, Scopus, and SPORTdiscus) were searched from the earliest record to 14 December 2019 to identify studies investigating cardiovascular structure and function in cyclists. Of the 4865 unique articles identified, 70 met inclusion criteria and of these, 22 articles presented 10 cardiovascular parameters in units relative to body size for meta-analysis and five presented data relating to incidence of cardiac abnormalities. Qualitative analysis was performed on remaining data. The overall quality of evidence was assessed using GRADE. Odds ratios were calculated to compare the incidence of cardiac abnormality.

RESULTS

Heart structure was significantly larger in cyclists compared to non-athletic controls for left ventricular: mass; end-diastolic volume, interventricular septal diameter and internal diameter; posterior wall thickness, and end-systolic internal diameter. Compared to high static and high dynamic sports (e.g., kayaking and canoeing), low-to-moderate static and moderate-to-high dynamic sports (e.g., running and swimming) and moderate-to-high static and low-to-moderate dynamic sports (e.g., bodybuilding and wrestling), endurance cyclists end-diastolic left ventricular internal diameter was consistently larger (mean difference 1.2-3.2 mm/m²). Cardiac abnormalities were higher in cyclists compared to controls (odds ratio: 1.5, 95%CI 1.2-1.8), but the types of cardiac abnormalities in cyclists were not different to other athletes.

CONCLUSION

Endurance cycling is associated with a larger heart relative to body size and an increased incidence of cardiac abnormalities relative to controls.

Time trends in physical activity in the Tromsø study: An update

Although the health benefits of physical activity are well documented, a large proportion of the population fails to meet current guidelines for physical activity. In order to develop evidence-based public health policies, surveillance of physical activity prevalence and trends is essential. The main aim of this study was to present updated data on physical activity trends in a Norwegian general population over the last decades. Data were collected from 40 690 individuals (50% men) aged ≥20 years participating in at least one of six surveys of the population-based Tromsø Study between 1979 and 2016. Age-standardized prevalences and trends in leisure-time and occupational physical activity were obtained from three questionnaires used in the different surveys. We observed an increase in the proportion engaging in exercise in leisure-time between 1994–95 and 2001 (p <0.001). Based on a different questionnaire, the age-standardized prevalence of engagement in exercise in leisure-time increased significantly from 16% in 2001 to 23% in 2007–08, and further to 28% in 2015–16 (p <0.001). The proportion who reported exercising approximately every day increased from 19% in 2007–08 to 28% in 2015–16 (p <0.001). The age-standardized prevalence of sedentary occupational activity increased from 53% in 2007–08 to 57% in 2015–16 (p <0.001), which extends the gradual increase from 36% in 1979-80.The present study extends previous findings from the Tromsø Study by demonstrating an increase in the proportion exercising regularly over the last three decades. This increase may partially counteract the gradual increase in the proportion with sedentary occupational activity.

Resting Heart Rate, Short-Term Heart Rate Variability and Incident Atrial Fibrillation (from the Multi-Ethnic Study of Atherosclerosis (MESA))

Evidence suggests an association between autonomical nervous system (ANS) function and atrial fibrillation (AF) development. We sought to examine the association of baseline resting heart rate (RHR) and short-term heart rate variability (HRV) as surrogates of (ANS) with incident AF in individuals without previous cardiovascular disease. A total of 6,261 participants of the Multi-Ethnic Study of Atherosclerosis who were free of AF and diagnosed cardiovascular disease were enrolled. Three standard 10-second, 12-lead electrocardiograms (ECG) were used to measure RHR, the standard deviation of normal-to-normal intervals (SDNN) and the root mean square of successive differences in RR intervals (RMSSD). Cox proportional hazards models adjusted for demographics, atrioventricular nodal agents, and known cardiovascular risk factors were used to examine the association of baseline RHR, and log transformed SDNN and RMSDD with incident AF. Over a mean follow-up of 11.3 ± 3.7 years, 754 (12%) participants developed AF. Spline curve analysis revealed a nonlinear association between RHR, HRV, and incident AF. In fully adjusted models higher (but not lower) baseline RHR (RHR >76 beats/min) was associated with incident AF (hazard ratio 1.48 95% confidence interval 1.18 to 1.86). Additionally, lower values of RMSDD and SDNN and higher values of RMSDD were independently associated with incident AF. In conclusion, cardiac ANS dysregulation indicated as higher RHR and lower HRV is associated with incident AF independent of known cardiovascular risk factors.

Physical Activity and Risk of Atrial Fibrillation: A Nationwide Cohort Study in General Population

Although exercise prevents cardiovascular disease and mortality, vigorous exercise and endurance athletics can cause atrial fibrillation (AF). However, no large cohort study has assessed the relationship between physical activity and AF in the general population. We assessed the effect of physical activity at different energy expenditures on the incidence of AF. We studied 501,690 individuals without pre-existing AF (mean age, 47.6 ± 14.3 years; 250,664 women [50.0%]) included in the Korean National Health Insurance Service database. The physical activity level was assessed using a standardized self-reported questionnaire at baseline. During a median follow-up of 4 years, 3,443 participants (1,432 women [41.6%]) developed AF. The overall incidence of AF at follow-up was 1.79 per 1,000 person-years. The subjects who met the recommended physical activity level (500–1,000 metabolic equivalent task [MET] minutes/week) had a 12% decreased AF risk (adjusted hazard ratio [HR]: 0.88, 95% confidence interval [CI]: 0.80–0.97), but not the insufficiently (1–500 MET-minutes/week; HR: 0.94, 95% CI: 0.86–1.03) and highly active subjects (≥1,000 MET-minutes/week; HR: 0.93, 95% CI: 0.85–1.03). The recommended minimum key target range of physical activity level was associated with the maximum benefit for reduced AF risk in the general population. The dose-response relationship between physical activity level and AF risk showed a U-shaped pattern. Although exceeding the key target range attenuated this benefit, it did not increase the AF risk beyond that during inactivity.

Long-Term Incidence of Atrial Fibrillation and Stroke Among Cross-Country Skiers

BACKGROUND

Studies have revealed a higher incidence of atrial fibrillation among well-trained athletes. We aim to investigate associations of endurance training with incidence of atrial fibrillation and stroke and to establish potential sex differences of such associations in a cohort of endurance trained athletes.

METHODS

All Swedish skiers (208 654) completing 1 or more races in the 30 to 90 km cross-country skiing event Vasaloppet (1989-2011) and a matched sample (n=527 448) of nonskiers were followed until first event of atrial fibrillation or stroke. Cox regression was used to investigate associations of number of completed races and finishing time with incidence of atrial fibrillation and stroke.

RESULTS

Female skiers in Vasaloppet had a lower incidence of atrial fibrillation than did female nonskiers (hazard ratio [HR], 0.55; 95% CI, 0.48-0.64), independent of finishing time and number of races. Male skiers had a similar incidence to that of nonskiers (HR, 0.98; 95% CI, 0.93-1.03). Skiers with the highest number of races or fastest finishing times had the highest incidence. Skiers of either sex had a lower incidence of stroke than did nonskiers (HR, 0.64; 95% CI, 0.60-0.67), independent of the number of races and finishing time. Skiers with atrial fibrillation had higher incidence of stroke than did skiers and nonskiers without atrial fibrillation (men: HR, 2.28; 95% CI, 1.93-2.70; women: HR, 3.51; 95% CI, 2.17-5.68; skiers with atrial fibrillation vs. skiers without atrial fibrillation). After diagnosis of atrial fibrillation, skiers with atrial fibrillation had a lower incidence of stroke (HR, 0.73; 95% CI, 0.50-0.91) and lower mortality compared with nonskiers with atrial fibrillation (HR, 0.57; 95% CI, 0.49-0.65).

CONCLUSIONS

Female skiers in Vasaloppet had lower incidence of atrial fibrillation and stroke. Male skiers had similar incidence of atrial fibrillation and lower risk of stroke. Men with higher number of races and faster finishing times had the highest incidence of atrial fibrillation. After diagnosis of atrial fibrillation, skiers had lower incidence of stroke and death than did nonskiers with atrial fibrillation. This indicates that although on an individual level atrial fibrillation in well-trained individuals is associated with higher incidence of stroke, on population level, risk of stroke is low and that exercise should not be avoided.

The association between obesity and cardiovascular disease mortality in different strata of socioeconomic position: evidence from pooled Norwegian health surveys

Background

Socioeconomic position (SEP) is related to both obesity and cardiovascular disease (CVD). There is little evidence on whether SEP modifies the relation between obesity and CVD. The aim of the study was to investigate whether the association between obesity and CVD mortality is stronger among people with disadvantaged than among people with advantaged life course SEP.

Methods

Data from Norwegian population-based cardiovascular health surveys (1985–2003), including body mass index and CVD risk factors (cholesterol, blood pressure, smoking, current treatment for hypertension) were linked to socioeconomic indicators from register and census data (1960–90), and to the Cause of Death Registry (up until 2014). The total number of participants was 398 297.

Results

In comparison with normal weight, the age-adjusted hazard ratios and 95% confidence intervals of CVD mortality among obese participants were 2.39 (2.07–2.75) and 2.08 (1.70–2.53) among men and women with high SEP, respectively and 1.88 (1.60–2.21) and 1.75 (1.43–2.14) among men and women with low SEP. Adjustment for CVD risk factors attenuated the results in a similar manner in all SEP groups, and among both women and men.

Conclusion

Obesity was consistently associated with a higher risk of CVD mortality, with only minor variation according to SEP. This means that preventing or treating obesity is, for the purpose of reducing CVD risk, equally important for an individual with high or low SEP.

Heart rate and premature atrial contractions at 24hECG independently predict atrial fibrillation in a population-based study

BACKGROUND

Low resting heart rate and premature atrial contractions (PACs) predict incident atrial fibrillation (AF) and could be interdependent, since PACs occur in the gaps between normal beats.

OBJECTIVE

To study the association between low heart rate at 24hECG, PACs and incident AF in a prospective population-based cohort.

METHODS

In the Malmö Diet and Cancer study, 24hECGs were performed in 377 AF-free subjects. The endpoint was clinical AF retrieved from national hospital (mean follow-up 17 years). The interaction between increased supraventricular activity (SVA) top quartile of either PACs/hour or supraventricular tachycardias/hour) and mean heart rate (mHR) as regards AF risk was assessed in multivariable Cox regression analyses adjusted for age, sex, height, BMI, systolic blood pressure, antihypertensive medication, smoking and homeostasis model assessment of insulin resistance.

RESULTS

There were 80 (21%) incident cases of AF. Below median mHR (80 bpm/75 bpm for women/men) was associated with increased AF incidence (HR: 1.89, 95% CI 1.18 to 3.02, p=0.008). There was no correlation between mHR and SVA (p=0.6) or evidence of a multiplicative interaction between these factors for AF risk (p for interaction=0.6) In the group with both increased SVA and below median mHR (17% of the population) the relative risk of AF was very high (HR 4.5, 95% CI 2.2 to 9.1, p=0.001).

CONCLUSION

Low mHR at 24hECG independently predicts AF, but there is no association between mHR and SVA, and these factors are independent as regards AF risk. Subjects with both low mHR and increased SVA have high AF risk.

Independent effect of physical activity and resting heart rate on the incidence of atrial fibrillation in the general population

While physical activity (PA) may influence resting heart rate (RHR), and a low RHR may be a risk factor for atrial fibrillation (AF), controversy exists regarding the association between PA and development of AF. Using data from a Korean, prospective population cohort, we investigated the independent effect of PA and RHR on the incidence of AF in the general population. A total of 8,811 participants aged 40-69 years were analyzed. Total PA assessed based on questionnaires was divided into quartiles, with the lowest to the highest being Q1, Q2, Q3, and Q4. During a median follow-up of 139 months, AF developed in 167 participants (1.9%). Q3 of total PA was associated with a significantly lower risk of AF than Q1 even after adjusting for RHR as a covariate, but Q4 was not. The risk of AF was higher in participants with RHR < 60 bpm than in those with RHR 70-85 bpm, and the significance persisted after adjusting for PA as a covariate. This study showed that a moderate amount of total PA was associated with a lower risk of incident AF independent of RHR and that low RHR was an independent risk factor for AF in the general Korean population.

Resting Heart Rate and the Risk of Atrial Fibrillation

In a previous meta-analysis, it was demonstrated that the resting heart rate (RHR) is a potential risk factor for atrial fibrillation (AF). However, the results of that meta-analysis were conflicting, and the relationship between the RHR and AF is still not well established. In the current meta-analysis, our aim is to update evidence with a better statistical model. We searched the Cochrane Library, PubMed, and Embase databases for relevant studies and used a "one-stage approach" with a restricted cubic spline model to summarize the dose-specific relationships between the RHR and AF. Relative risk (RR) was used to measure the effects. In total, 10 studies were included, with a total of 18,630 cases of AF among 431,432 participants. In the dose-response analysis, there was evidence of a nonlinear association between the RHR and the risk of AF (nonlinearity, P < 0.0001), which exhibited a significant J-shaped association between the two factors. An RHR between 68 and 80 bpm had the lowest risk of AF. Among people who had RHR < 70 bpm, the summary RR was 1.09 per 10-RHR decrease (95% confidence interval [CI] = 1.06-1.12; P < 0.001). The results were similar for participants with RHR > 70 bpm (per 10 bpm increase) (RR = 1.06, 95% CI = 1.03-1.08; P < 0.001). Our dose-response meta-analysis revealed a significant J-shaped association between the RHR and AF. Both low RHR and high RHR were associated with an increased risk of AF compared with a modest RHR of 68-80 bpm.

Association between self-reported physical activity and incident atrial fibrillation in a young Korean population

The association between physical activity (PA) and atrial fibrillation (AF) remains unclear. We thus investigated association of PA with the development of AF. Type and duration data for PA were acquired from 211,992 AF-free individuals using the validated Korean version of the International Physical Activity Questionnaire Short From between March 2002 and December 2014. Individuals were divided into four groups according to self-reported PA level and previous international PA guidelines: no PA with a sedentary lifestyle, insufficient PA, sufficient PA, and health-enhancing PA. AF was diagnosed by annual 12-lead electrocardiogram. During a median follow-up of 5.6 years, AF occurred in 304 participants (annual AF incidence rate 2.5/10,000 person-years). After adjusting for age and sex, PA level was not associated with AF incidence (P for trend = 0.26). The multivariable-adjusted hazard ratios (95% confidence interval) for incidental AF was 1.00 (0.74–1.37) for the insufficient PA group, 1.34 (0.91–1.97) for the sufficient PA group, and 1.27 (0.72–2.23) for the health-enhancing PA group compared with the no PA group (P for trend = 0.18). Thus, our study does not support an association between the risk of AF and PA level in a young Korean population.

Physical activity may compensate for prolonged TV time regarding pulse rate-a cross-sectional study

BACKGROUND

Regular exercise reduces pulse rate, but it is less clear how prolonged sitting time affects pulse rate. Our hypothesis was that high physical activity could compensate for prolonged sitting time regarding the pulse rate.

METHODS

Regression analysis was performed on cross-sectional data including 47,457 men and women based on two Swedish cohort studies, EpiHealth (18-45 years) and LifeGene (45-75 years). Self-reported leisure time physical activity was given in five levels, from low (level 1) to vigorous (level 5), and television time was used as a proxy of sitting time.

RESULTS

A higher physical activity (level 4 compared to level 1) was associated with a lower pulse rate in middle-aged females (-2.7 beats per minute [bpm]; 95% CI -3.3 to -2.2) and males (-4.0 bpm; 95% CI -4.7 to -3.4). The relationship between physical activity and pulse rate was strongest in the young. A prolonged television time (3 h compared to 1 h per day) was associated with a slightly higher pulse rate in middle-aged females (+0.6 bpm; 95% CI +0.3 to +0.8) and males (+0.9 bpm; 95% CI +0.7 to +1.2). Among participants with a prolonged television time (3 h), those with a high physical activity (level 4) had a lower pulse rate compared to those with a low physical activity (level 1).

CONCLUSIONS

A prolonged television time was associated with a high pulse rate, while high physical activity was associated with a low pulse rate. The results suggest that a high physical activity could compensate for a prolonged television time regarding pulse rate.

Competitive Endurance Activities of Middle-aged Athletes as a Risk Factor for Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia in athletes. Epidemiological studies have documented a greater prevalence of AF in athletes engaged in long-term endurance sports. Several mechanisms were proposed to underlie the association between exercise and AF, but the exact pathophysiology remains unclear. The studies up to now have been concentrated on the competitive middle-aged endurance athletes, but there is no evidence of AF prevalence among highly active noncompetitive athletes of the same age. Endurance athletes who do not compete might be at a lower risk for AF than their competitive peers. This hypothesis is theoretically examined, and the current evidence summarized in this article.

Exercise and Atrial Fibrillation: Some Good News and Some Bad News

Atrial fibrillation (AF) is considered as the most common sustained arrhythmia in adults, whose incidence rate is on the rise due to the increase in the mean age of the global population. In recent years, many efforts have been made to identify effective factors in the incidence of AF to prevent them and thereby reduce the consequences of AF. Physical activity is one of the topics that attracted much attention in the last two decades. According to some findings, extreme and prolonged exercise itself can be considered as a risk factor for the onset of AF; however, other studies have shown that exercise can be regarded a protective factor against AF in the general population. The present study reviews the findings of studies on the relationship between AF and exercise and discusses possible mechanisms for this relationship. Additionally, we present some recommendations for researchers and physicians about exercise management in association with AF prevention.

The Limits of Cardiac Performance: Can Too Much Exercise Damage the Heart?

Routine moderate-intensity physical activity confers numerous cardiovascular benefits and reduces all-cause mortality. However, the health impact of exercise doses that exceed contemporary physical activity guidelines remains incompletely understood, and an emerging body of literature suggests that high levels of exercise may have the capacity to damage the cardiovascular system. This review focuses on the contemporary controversies regarding high-dose exercise and cardiovascular morbidity and mortality. We discuss the limitations of available studies, explore potential mechanisms that may mediate exercise-related cardiac injury, and highlight the gaps in knowledge for future research.

The association between BMI and mortality using early adulthood BMI as an instrumental variable for midlife BMI

The article aims to describe the association between midlife body mass index (BMI) and cardiovascular disease (CVD)- and all-cause mortality, and to use early adulthood BMI as an instrumental variable for midlife BMI, in order to obtain an estimate less distorted by midlife confounders and reverse causality. Data from Norwegian health surveys (1974–2003) (midlife BMI, smoking, blood pressure, total cholesterol, heart rate), Military Conscription Records, National Tuberculosis Screenings (early adulthood BMI), National Educational Registry and Cause of Death Registry were linked. Participants with data on BMI in early adulthood and midlife were included (n = 148.886). Hazard Ratio (HR) for CVD mortality was higher in men with midlife obesity relative to normal weight (HR = 1.46(95% CI 1.25, 1.70). For all-cause mortality, HR was higher in those with obesity or underweight in midlife relative to normal weight (Men:HR = 1.19(95% CI 1.09, 1.29), HR = 2.49(95% CI 1.81, 3.43) Women:HR = 1.33(95% CI 1.13, 1.56), HR = 1.61(95% CI 1.22, 2.13)). In instrumental variable analyses, increased BMI became more strongly associated with CVD and all-cause mortality, and the increased risk of all-cause mortality among the underweight attenuated.

Physical activity modifies the risk of atrial fibrillation in obese individuals: The HUNT3 study

Background

Atrial fibrillation is the most common heart rhythm disorder, and high body mass index is a well-established risk factor for atrial fibrillation. The objective of this study was to examine the associations of physical activity and body mass index and risk of atrial fibrillation, and the modifying role of physical activity on the association between body mass index and atrial fibrillation.

Design

The design was a prospective cohort study.

Methods

This study followed 43,602 men and women from the HUNT3 study in 2006–2008 until first atrial fibrillation diagnosis or end of follow-up in 2015. Atrial fibrillation diagnoses were collected from hospital registers and validated by medical doctors. Cox proportional hazard regression analysis was performed to assess the association between physical activity, body mass index and atrial fibrillation.

Results

During a mean follow-up of 8.1 years (352,770 person-years), 1459 cases of atrial fibrillation were detected (4.1 events per 1000 person-years). Increasing levels of physical activity were associated with gradually lower risk of atrial fibrillation ( p trend 0.069). Overweight and obesity were associated with an 18% (hazard ratio 1.18, 95% confidence interval 1.03–1.35) and 59% (hazard ratio 1.59, 95% confidence interval 1.37–1.84) increased risk of atrial fibrillation, respectively. High levels of physical activity attenuated some of the higher atrial fibrillation risk in obese individuals (hazard ratio 1.53, 95% confidence interval 1.03–2.28 in active and 1.96, 95% confidence interval 1.44–2.67 in inactive) compared to normal weight active individuals.

Conclusion

Overweight and obesity were associated with increased risk of atrial fibrillation. Physical activity offsets some, but not all, atrial fibrillation risk associated with obesity.

Excessive exercise in endurance athletes: Is atrial fibrillation a possible consequence?

Moderate physical activity levels are associated with increased longevity and lower risk of atrial fibrillation (AF). However, the relative risk of lone AF is 3-5-fold higher in intensive endurance-trained athletes compared with healthy adults. There is growing concern that "excessive" endurance exercise may promote cardiac remodelling, leading to long-term adverse consequences. The pathogenesis of exercise-induced AF is thought to arise from an interplay of multiple acute and chronic factors, including atrial enlargement, pro-fibrotic tendency, high vagal tone, and genotypic profile, which collectively promote adverse atrial remodelling. Clinical management of athletes with AF, while challenging, can be achieved using various strategies that may allow continued, safe exercise. Based on the overall risk-benefit evidence, it is premature to suggest that excessive exercise is unsafe or should be curtailed. Evidence-based assessment and treatment guidelines are required to ensure optimal and safe exercise among the growing number of endurance athletes with AF.

Paroxysmal atrial fibrillation in young and middle-aged athletes (PAFIYAMA) syndrome in the real world: a paradigmatic case report

An enhanced risk of atrial fibrillation (AF) has been clearly documented in endurance athletes over the past decades. In this regard, we have recently described the 'PAFIYAMA' ('paroxysmal AF in young and middle-aged athletes') syndrome, provided that other risk factors for AF and underlying conditions have been ruled out. We report here a paradigmatic case of PAFIYAMA syndrome. A 32 years old man was admitted to the Emergency Department (ED) complaining for palpitations, lasting for 3 hours. He had never smoked and other risk factors for AF could be ruled out. The electrocardiogram (ECG) was consistent with AF at high ventricular response (130-150 bpm). All laboratory parameters were within the respective reference ranges, and laboratory screening for cocaine, amphetamine, and MDMA was negative. After 12 hours of persistent AF, the patient underwent effective electrical cardioversion. The patient reported an episode of paroxysmal AF (PAF), occurred during practicing strenuously training for a martial arts competition 2 years before the current episode. In the last two weeks, in addition to usual training, the patient was engaged in carrying heavy furniture. He underwent echocardiography within a week from ED discharge, showing a physiologic athlete's left ventricle (LV) hypertrophy. The patient was discharged with suggestion to reduce his training regimen. A Holter-ECG performed one month after ED discharge showed no signs of arrhythmia, and the patient remained asymptomatic during the following six months of follow-up. Therefore, following the diagnostic algorithm of PAFIYAMA syndrome, this patient can be considered as a paradigmatic case of this recently described syndrome. The potential clinical implications and the impact on patients' lifestyle are meaningful. New-onset AF in young population is uncommon. For that reason, physicians should be aware about PAFIYAMA syndrome.

Physical activity volume in relation to risk of atrial fibrillation. A non-linear meta-regression analysis

Background

Light physical activity is known to reduce atrial fibrillation risk, whereas moderate to vigorous physical activity may result in an increased risk. However, the question of what volume of physical activity can be considered beneficial remains poorly understood. The scope of the present work was to examine the relation between physical activity volume and atrial fibrillation risk.

Design

A comprehensive systematic review was performed following the PRISMA guidelines.

Methods

A non-linear meta-regression considering the amount of energy spent in physical activity was carried out. The first derivative of the non-linear relation between physical activity and atrial fibrillation risk was evaluated to determine the volume of physical activity that carried the minimum atrial fibrillation risk.

Results

The dose–response analysis of the relation between physical activity and atrial fibrillation risk showed that physical activity at volumes of 5–20 metabolic equivalents per week (MET-h/week) was associated with significant reduction in atrial fibrillation risk (relative risk for 19 MET-h/week = 0.92 (0.87, 0.98). By comparison, physical activity volumes exceeding 20 MET-h/week were unrelated to atrial fibrillation risk (relative risk for 21 MET-h/week = 0.95 (0.88, 1.02).

Conclusion

These data show a J-shaped relation between physical activity volume and atrial fibrillation risk. Physical activity at volumes of up to 20 MET-h/week is associated with reduced atrial fibrillation risk, whereas volumes exceeding 20 MET-h/week show no relation with risk.

The ambiguity of physical activity, exercise and atrial fibrillation

Although commonly associated with cardiovascular disease or other medical conditions, atrial fibrillation may also occur in individuals without any known underlying conditions. This manifestation of atrial fibrillation has been linked to extensive and long-term exercise, as prolonged endurance exercise has shown to increase prevalence and risk of atrial fibrillation. In contrast, more modest physical activity is associated with a decreased risk of atrial fibrillation, and current research indicates a J-shaped association between atrial fibrillation and the broad range of physical activity and exercise. This has led to the hypothesis that the mechanisms underlying an increased risk of atrial fibrillation with intensive exercise are different from those underlying a reduced risk with moderate physical activity, possibly linked to distinctive characteristics of the population under study. High volumes of exercise over many years performed by lean, healthy endurance trained athletes may lead to cardiac (patho)physiological alterations involving the autonomic nervous system and remodelling of the heart. The mechanisms underlying a reduced risk of atrial fibrillation with light and moderate physical activity may involve a distinctive pathway, as physical activity can potentially reduce the risk of atrial fibrillation through favourable effects on cardiovascular risk factors.

Impact of Cardiorespiratory Fitness on Frequency of Atrial Fibrillation, Stroke, and All-Cause Mortality

Benefits of cardiorespiratory fitness on cardiovascular health are well recognized, but the impact on incidence of atrial fibrillation (AF) and stroke, and, particularly, risk of stroke and mortality in patients with AF is less clear. From 1993 to 2010, patients referred for a treadmill exercise test (TMET) at the Mayo Clinic Rochester, MN, were retrospectively identified (N = 76,857). From this, 14,094 local residents were selected. Exclusions were age <18 years; history of heart failure, structural or valvular heart disease, AF or flutter, or stroke. Subjects were divided into 4 groups at baseline based on quartiles of functional aerobic capacity (FAC) and followed through January 2016. The final study cohort included 12,043 patients. During median follow-up of 14 (9 to 17) years, 1,222 patients developed incident AF, 1,128 developed stroke, and 1,590 patients died. Each 10% increase in FAC was associated with decreased risk of incident AF, stroke, and mortality by 7% (0.93 [0.91 to 0.96, p < 0.001]), 8% (0.92 [0.89 to 0.94, p < 0.001]), and 16% (0.84 [0.82 to 0.86, p < 0.001]), respectively. In patients who developed incident AF with baseline FAC <75% versus ≥105%, risks of both stroke (1.40 [1.04 to 1.90, p = 0.01]) and mortality (3.20 [2.11 to 4.58, p < 0.001]) were significantly higher. In conclusion, better cardiorespiratory fitness is associated with lower risk of incident AF, stroke, and mortality. Similarly, risk of stroke and mortality in patients with AF is also inversely associated with cardiorespiratory fitness.

Management of Arrhythmias in Athletes: Atrial Fibrillation, Premature Ventricular Contractions, and Ventricular Tachycardia

OPINION STATEMENT

Management of atrial fibrillation, premature ventricular contractions, and ventricular tachycardia without underlying cardiac disease or arrhythmogenic conditions differs in athletes from the general population. Athletes tend to be younger, healthier individuals with few comorbidities. Therapies that work well in the general population may not be appropriate or preferable for athletes. Management strategies include deconditioning, pharmacologic therapy, such as rate control with β-blockers or non-dihydropyridine calcium channel blockers and rhythm control with class I or class III antiarrhythmic drugs, and catheter ablation. Deconditioning is not preferred by athletes because of lost playing time. Pharmacologic therapy is well tolerated among most individuals, but is not as favorable in athletes. Rate control medications can reduce performance and β-blockers, in particular, are prohibited in many sports. Antiarrhythmic drugs are preferred over rate control with athletes, but many, especially younger athletes, may not like the idea of long-term medical therapy. Catheter ablation has been proven to be safe and efficacious, may eliminate the need for long-term medical therapy, and is supported by the major societies (AHA, ACC, ESC).

The effects of different physical activities on atrial fibrillation in patients with hypertension and chronic kidney disease

Background

Atrial fibrillation (AF) is highly common, and is most frequently observed in individuals with hypertension and structural cardiac disease. Sympathetic hyperactivity plays a fundamental role in the progression, maintenance and aggravation of arrhythmia. Endurance exercise training clearly lowers sympathetic activity in sympathoexcitatory disease states, and is well-tolerated by patients with chronic kidney disease (CKD).

Methods

We assessed 50 CKD patients with hypertension. Each patient provided a complete medical history and underwent a physical examination. We used an implantable cardiac monitor over a 3-year follow-up period to evaluate the effects of high-intensity interval training (HIIT) and moderate exercise (ModEx) physical activity protocols on AF occurrence, and determined the effectiveness of these protocols in improving renal function. Subjects were followed up every 6 months after the beginning of the intervention.

Results

During the 3-year follow-up, AF onset was higher in CKD patients who engaged in HIIT (72%) than in those who engaged in ModEx (24%) (hazard ratio, 3.847; 95% confidence interval, 1.694–8.740, P = 0.0013 by log-rank test). Both groups exhibited significant intra-group changes in the mean systolic 24-hour ambulatory blood pressure measurements (ABPM) between baseline and 12, 24, and 36 months. There were also significant differences in the mean systolic 24-hour ABPM between the groups at the same time points.

Conclusion

In CKD patients with hypertension, improvements in AF onset, renal function and some echocardiographic parameters were more evident in subjects who engaged in ModEx than in those who engaged in HIIT during 3 years of follow-up.