Physical activity, resting heart rate, and atrial fibrillation: the Tromsø Study

The causal relationship between sarcopenia-related traits and ECG indices - A mendelian randomization study

BACKGROUND

Sarcopenia is a common geriatric condition closely associated with cardiovascular diseases and other health issues. This study aims to investigate the causal relationship between sarcopenia-related traits and electrocardiogram(ECG) indices.

METHODS

We conducted a comprehensive analysis utilizing summary data from genome-wide association studies (GWAS) associated with sarcopenia-related traits, including hand grip strength, lean body mass, and walking pace. ECG indices included PR interval, PP interval, ST duration, QRS duration and T wave duration. The primary analytical method employed was the inverse variance-weighted method (IVW).

RESULTS

According to our study findings, we identified a significant association between sarcopenia-related traits and ECG indices. Specifically, we observed a positive correlation between increased muscle mass and certain ECG indices. For instance, increased limb muscle mass (including left arm, right arm, left leg, and right leg) was associated with prolonged PR interval and QRS duration. This suggests that enhancing muscle mass may impact the timing of cardiac electrical activity. Additionally, increased whole-body fat-free mass showed similar associations with cardiac electrical activity.

CONCLUSION

Sarcopenia-related traits have a unidirectional causal relationship with ECG indices, indicating that sarcopenia affects cardiac electrical activity.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

Previous Exercise Levels and Outcome in Patients with New Atrial Fibrillation: "Past Achievements Do Not Predict the Future"

INTRODUCTION

Long-term endurance exercise is suspect to elevate the risk of atrial fibrillation (AF), but little is known about cardiovascular outcome and disease progression in this subgroup of AF patients. We investigated whether previous exercise level determines cardiovascular outcome.

METHODS

In this post hoc analysis of the RACE 4 randomized trial, we analyzed all patients with a completed questionnaire on sports participation. Three subgroups were made based on lifetime sports hours up to randomization and previous compliance to the international physical activity guidelines. High lifetime hours of high dynamic activity patients were defined as more than 150 min·wk -1 of high-intensity physical exercise. The primary endpoint was a composite of cardiovascular death and hospital admissions.

RESULTS

A total of 879 patients were analyzed, divided in 203 high lifetime hours of high dynamic activity, 192 high lifetime hours of activity, and 484 low lifetime hours of activity patients. Over a mean follow-up of 36 months (±14), the primary endpoint occurred in 61 out of 203 (30%) high lifetime hours of high dynamic activity, 53 out of 192 (27%) high lifetime hours of activity, and 135 out of 484 (28%) low lifetime hours of activity patients ( P = 0.74). During follow-up, 42 high lifetime hours of high dynamic activity (35%), 43 high lifetime hours of activity (32%), and 104 low lifetime hours of activity patients (34%) with paroxysmal AF received electrical or chemical cardioversion or atrial ablation ( P = 0.90).

CONCLUSIONS

In patients included in the RACE 4, there seems to be no relation between previous activity levels and cardiovascular outcome and the need for electrical or chemical cardioversion or atrial ablation. Cardiovascular outcome was driven by AF-related arrhythmic events.

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.

Association Between Physical Activity and the Prevalence of Kidney Stones in American Adults: Results From a Multiyear National Survey

OBJECTIVE

To investigate the association between physical activity (PA) and the prevalence of kidney stones.

METHODS

A cross-section study was conducted using data from National Health and Nutrition Examination Survey 2007-2018. PA was evaluated based on the Global Physical Activity Questionnaire. Multivariable logistic regression was performed to elucidate the association between PA (patterns, intensity, duration, and frequency of moderate and vigorous PA) and the prevalence of kidney stones after adjusting for potential confounders. Stratified and interaction analyses were conducted to detect potential effect modifiers. In addition, PA was assessed using metabolic equivalent and physical volume, and followed the regression above. Water intake was obtained from the day 2 dietary recall and was included in the sensitivity analysis.

RESULTS

A total of 34,390 participants were included in the analysis. The multivariable logistic regression revealed that individuals who engaged in moderate PA for 30-60 minutes per day had a significant inverse association with the prevalence of kidney stones in the fully adjusted model (odds ratio=0.804, 95% confidence interval 0.700 to 0.923), while no more significant finding was observed for other PA parameters. Interaction and stratified analyses indicated no covariate modifying the association. The results above were robust in the sensitivity analysis.

CONCLUSION

The duration of moderate PA (30-60 min/d) is inversely associated with the prevalence of kidney stones, while no more significant association was observed between other PA parameters (including patterns, intensity, duration, and frequency of vigorous PA, frequency of moderate PA) and kidney stones.

Racial and Gender Differences in Cardiorespiratory Fitness and Atrial Fibrillation

The expanding field of cardiorespiratory fitness (CRF) in individuals with and without atrial fibrillation (AF) presents a complex landscape, demanding careful interpretation of the existing research. AF, characterized by significant mortality and morbidity, prompts the exploration of strategies to mitigate its impact. Increasing physical activity (PA) levels emerges as a promising avenue to address AF risk factors, such as obesity, hypertension, and diabetes mellitus, through mechanisms of reduced vasoconstriction, endothelin-1 modulation, and improved insulin sensitivity. However, caution is warranted, as recent investigations suggest a heightened incidence of AF, particularly in athletes engaged in high-intensity exercise, due to the formation of ectopic foci and changes in cardiac anatomy. Accordingly, patients should adhere to guideline-recommended amounts of low-to-moderate PA to balance benefits and minimize adverse effects. When looking closer at the current evidence, gender-specific differences have been observed and challenged conventional understanding, with women demonstrating decreased AF risk even at extreme exercise levels. This phenomenon may be rooted in divergent hemodynamic and structural responses to exercise between men and women. Existing research is predominantly observational and limited to racially homogenous populations, which underscores the need for comprehensive studies encompassing diverse, non-White ethnic groups in athlete and non-athlete populations. These individuals exhibit a disproportionately high burden of AF risk factors that could be addressed through improved CRF. Despite the limitations, randomized control trials offer promising evidence for the efficacy of CRF interventions in patients with preexisting AF, showcasing improvements in clinically significant AF outcomes and patient quality of life. The potential of CRF as a countermeasure to the consequences of AF remains an area of great promise, urging future research to delve deeper to explore its role within specific racial and gender contexts. This comprehensive understanding will contribute to the development of tailored strategies for optimizing cardiovascular health and AF prevention in all those who are affected.

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.

2024 HRS expert consensus statement on arrhythmias in the athlete: Evaluation, treatment, and return to play

Youth and adult participation in sports continues to increase, and athletes may be diagnosed with potentially arrhythmogenic cardiac conditions. This international multidisciplinary document is intended to guide electrophysiologists, sports cardiologists, and associated health care team members in the diagnosis, treatment, and management of arrhythmic conditions in the athlete with the goal of facilitating return to sport and avoiding the harm caused by restriction. Expert, disease-specific risk assessment in the context of athlete symptoms and diagnoses is emphasized throughout the document. After appropriate risk assessment, management of arrhythmias geared toward return to play when possible is addressed. Other topics include shared decision-making and emergency action planning. The goal of this document is to provide evidence-based recommendations impacting all areas in the care of athletes with arrhythmic conditions. Areas in need of further study are also discussed.

Thromboembolic prevention in athletes: management of anticoagulation in sports players affected by atrial fibrillation

Atrial fibrillation (AF) is a common cardiac arrhythmia that poses a significant risk of stroke and thromboembolic events. Anticoagulation therapy is essential for preventing stroke in patients with AF. An increasing number of people of all ages, including cardiac patients, approach physical activity as both a leisure-time exercise and a competitive sport. Therefore, patients at risk of AF are increasingly allowed to practice sports activities. Management of oral anticoagulant therapy (OAT) in these patients is extremely challenging because of the need to balance the risks and benefits of medications, considering both hemorrhagic (in case of trauma) and ischemic complications when the drugs are avoided. Official recommendations are limited for these patients and forbid sports that increase the risk of trauma and consequent bleeding in most cases. These recommendations are strongly influenced by the "traditional" management of OAT, which mainly involves coumarin derivatives. Non-vitamin K antagonist direct oral anticoagulants (DOACs), with their more favorable pharmacokinetic-pharmacodynamic profile than that of coumarin derivatives, may represent an opportunity to modify the approach to sports activity in patients with AF and indications for OAT. This study aimed to review the use of anticoagulants in athletes with AF, highlight their efficacy and safety, and provide practical considerations regarding their management.

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.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Associations of Dietary and Lifestyle Components with Atrial Fibrillation

Atrial fibrillation (AF) is a prevalent cardiac arrhythmia that still remains a significant health concern, especially due to its consequences, including stroke and heart failure. This review explores the intricate interplay between AF, lifestyle choices, and dietary habits. It is particularly focused on findings from diverse studies about non-pharmacological methods of managing AF. Moreover, its purpose is to elucidate the implementation of lifestyle changes such as physical activity or proper diet choices in the integrated treatment strategy of patients with 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.

Exerkine β-aminoisobutyric acid protects against atrial structural remodeling and atrial fibrillation in obesity via activating AMPK signaling and improving insulin sensitivity

Moderate exercise decreases the risk for atrial fibrillation (AF), an effect which is probably mediated via exercise-stimulated release of exerkines. β-Aminoisobutyric acid (BAIBA), a novel exerkine, has been reported to provide protective benefits against many cardiovascular diseases, yet its role in AF remains elusive. Herein, using a mouse model of obesity-related AF through high-fat diet (HFD) feeding, we found that 12-week drinking administration of BAIBA (170 mg/kg/day) decreased AF susceptibility in obese mice. Atrial remodeling assessment showed that BAIBA attenuated obesity-induced atrial hypertrophy and interstitial fibrosis, thereby ablating the substrate for AF. Of note, to our knowledge, this is the first report of the direct association of BAIBA and hypertrophy. BAIBA has been reported to be a key regulator of glucose and lipid metabolism, and we found that BAIBA alleviated insulin resistance in obese mice. Transcriptional analysis of metabolism-related genes showed that BAIBA increased the transcription of fatty acids metabolism-related genes in the atria of lean mice but not in that of obese mice. Mechanistic investigation showed that BAIBA stimulated AMP-activated protein kinase (AMPK) signaling in the atria of obese mice and palmitic acid (PA)-treated neonatal rat cardiomyocytes (NRCM), whereas inhibition of AMPK via Compound C attenuated BAIBA-conferred cardioprotection against hypertrophy and insulin resistance in PA-treated NRCM. Collectively, BAIBA attenuates AF susceptibility in obese mice via activated AMPK signaling and resultant improvement of insulin sensitivity, thereby providing perspectives on the potential therapeutic role of BAIBA in AF treatment.

Effects of different exercise methods and intensities on the incidence and prognosis of atrial fibrillation

Atrial fibrillation (AF), the most common sustained arrhythmia in clinical practice, exhibits a higher risk of cardiovascular adverse events. Exercise plays a crucial role in AF prevention, but the effects of different exercise types and doses are inconclusive. This review aims to comprehensively explore the most recent evidence and possible mechanisms of diverse exercise modalities concerning AF incidence and therapeutic outcomes. Multiple studies underscore the efficacy of moderate-intensity continuous training (MICT) in reducing AF incidence and symptom burden, rendering it the currently favored exercise therapy for AF patients. High-intensity interval training (HIIT) shows promise, potentially surpassing MICT, especially in reducing age-related AF susceptibility and improving symptoms and exercise capacity. Conversely, prolonged high-intensity endurance exercise exacerbates AF risk due to excessive exercise volume, with potential mechanisms encompassing irreversible atrial remodeling, heightened inflammation, and increased vagal tone. In summation, MICT is a secure strategy for populations in mitigating the risk associated with AF incidence and secondary cardiovascular events and should be encouraged. Also, it is recommended to initiate large-scale clinical intervention trials encompassing a variety of exercise types to delineate the optimal exercise prescription for cardiovascular patients, including those afflicted with AF.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation" provides recommendations to guide clinicians in the treatment of patients with atrial fibrillation.

METHODS

A comprehensive literature search was conducted from May 12, 2022, to November 3, 2022, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through November 2022, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Atrial fibrillation is the most sustained common arrhythmia, and its incidence and prevalence are increasing in the United States and globally. Recommendations from the "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" and the "2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" have been updated with new evidence to guide clinicians. In addition, new recommendations addressing atrial fibrillation and thromboembolic risk assessment, anticoagulation, left atrial appendage occlusion, atrial fibrillation catheter or surgical ablation, and risk factor modification and atrial fibrillation prevention have been developed.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Patients With Atrial Fibrillation" provides recommendations to guide clinicians in the treatment of patients with atrial fibrillation.

METHODS

A comprehensive literature search was conducted from May 12, 2022, to November 3, 2022, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through November 2022, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Atrial fibrillation is the most sustained common arrhythmia, and its incidence and prevalence are increasing in the United States and globally. Recommendations from the "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" and the "2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" have been updated with new evidence to guide clinicians. In addition, new recommendations addressing atrial fibrillation and thromboembolic risk assessment, anticoagulation, left atrial appendage occlusion, atrial fibrillation catheter or surgical ablation, and risk factor modification and atrial fibrillation prevention have been developed.

Hypothetical interventions and risk of atrial fibrillation by sex and education: application of the parametric g-formula in the Tromsø Study

AIMS

To use the parametric g-formula to estimate the long-term risk of atrial fibrillation (AF) by sex and education under hypothetical interventions on six modifiable risk factors.

METHODS AND RESULTS

We estimated the risk reduction under hypothetical risk reduction strategies for smoking, physical activity, alcohol intake, body mass index, systolic, and diastolic blood pressure in 14 923 women and men (baseline mean age 45.8 years in women and 47.8 years in men) from the population-based Tromsø Study with a maximum of 22 years of follow-up (1994-2016). The estimated risk of AF under no intervention was 6.15% in women and 13.0% in men. This cumulative risk was reduced by 41% (95% confidence interval 17%, 61%) in women and 14% (-7%, 30%) in men under joint interventions on all risk factors. The most effective intervention was lowering body mass index to ≤ 25 kg/m2, leading to a 16% (4%, 25%) lower risk in women and a 14% (6%, 23%) lower risk in men. We found significant sex-differences in the relative risk reduction by sufficient physical activity, leading to a 7% (-4%, 18%) lower risk in women and an 8% (-2%, -13%) increased risk in men. We found no association between the level of education and differences in risk reduction by any of the interventions.

CONCLUSION

The population burden of AF could be reduced by modifying lifestyle risk factors. Namely, these modifications could have prevented 41% of AF cases in women and 14% of AF cases in men in the municipality of Tromsø, Norway during a maximum 22-year follow-up period.

Insight into the relationship between resting heart rate and atrial fibrillation: a Mendelian randomization study

AIMS

A low resting heart rate (RHR) implies a more efficient heart function and a lower risk of cardiovascular disease. However, observational studies have reported a U-shaped association between RHR and atrial fibrillation (AF). In contrast, Mendelian randomization (MR) studies have found an inverse causal association between RHR and AF. Hence, the causal nature of the relationship is not clear. The aim is to investigate the causal association and its shape between RHR on AF using linear and non-linear MR (NLMR).

METHODS AND RESULTS

Linear and non-linear MR were performed on individual-level data in the Trøndelag Health Study (HUNT) and UK Biobank (UKB). HUNT consists of 69 155 individuals with 7,062 AF cases, while UKB provides data on 431 852 individuals with 20 452 AF cases. The linear MR found an inverse relationship between RHR and AF with an OR = 0.95 [95% confidence interval (CI): 0.93-0.98] and OR = 0.96 (95% CI: 0.95-0.97) per unit decrease in RHR in HUNT and UKB, respectively. The NLMR was supportive of an inverse linear relationship in both HUNT and UKB for RHR values <90 beats per minute (bpm). Several sensitivity analyses were also consistent.

CONCLUSION

In contrast with the current observational knowledge of RHR and AF, an inverse causal association between RHR and AF was demonstrated in both linear and non-linear MR for RHR values up to 90 bpm. Further exploring the underlying mechanisms of the genetic instrument for RHR may shed light on whether pleiotropy is biasing this association.

Long-Term Training Increases Atrial Fibrillation Sustainability in Standardbred Racehorses

Atrial fibrillation (AF) is more prevalent in athletes, and currently, the mechanisms are not fully understood. Atrial fibrillation inducibility and stability was investigated in trained and untrained Standardbred racehorses. The horses underwent echocardiography for evaluation of atrial size. High-density mapping during AF was performed, and the presence of structural remodeling, as well as the expression of inflammatory and pro-inflammatory markers in the atria, was studied. Atrial fibrillation sustained significantly longer after tachypacing in the trained horses, whereas no difference in AF inducibility was found. The untrained horses displayed a significant difference in the AF complexity when comparing right and left atria, whereas such difference was not observed in the trained animals. No evidence of increased structural remodeling or inflammation could be identified. Left atrial dimensions were not significantly increased. The increased AF sustainability in trained horses was not related to fibrosis or inflammation as seen in other animal exercise models.

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.

Development of algorithm for work intensity evaluation using excess overwork index of construction workers with real-time heart rate measurement device

Background

The construction workers are vulnerable to fatigue due to high physical workload. This study aimed to investigate the relationship between overwork and heart rate in construction workers and propose a scheme to prevent overwork in advance.

Methods

We measured the heart rates of construction workers at a construction site of a residential and commercial complex in Seoul from August to October 2021 and develop an index that monitors overwork in real-time. A total of 66 Korean workers participated in the study, wearing real-time heart rate monitoring equipment. The relative heart rate (RHR) was calculated using the minimum and maximum heart rates, and the maximum acceptable working time (MAWT) was estimated using RHR to calculate the workload. The overwork index (OI) was defined as the cumulative workload evaluated with the MAWT. An appropriate scenario line (PSL) was set as an index that can be compared to the OI to evaluate the degree of overwork in real-time. The excess overwork index (EOI) was evaluated in real-time during work performance using the difference between the OI and the PSL. The EOI value was used to perform receiver operating characteristic (ROC) curve analysis to find the optimal cut-off value for classification of overwork state.

Results

Of the 60 participants analyzed, 28 (46.7%) were classified as the overwork group based on their RHR. ROC curve analysis showed that the EOI was a good predictor of overwork, with an area under the curve of 0.824. The optimal cut-off values ranged from 21.8% to 24.0% depending on the method used to determine the cut-off point.

Conclusion

The EOI showed promising results as a predictive tool to assess overwork in real-time using heart rate monitoring and calculation through MAWT. Further research is needed to assess physical workload accurately and determine cut-off values across industries.

Resting heart rate and risk of atrial fibrillation in Chinese general population: Kailuan prospective cohort study

OBJECTIVE

Previous research has shown an association of higher heart rate with an increased risk of atrial fibrillation (AF). However, the relationship between resting heart rate (RHR) and AF is unknown. The aim of this study was to investigate the association between RHR and AF in the general population of China.

DESIGN

Prospective observational cohort study.

SETTING

Community based.

PARTICIPANTS

A total of 46 126 individuals from the Kailuan study who participated in the first three surveys (2006/2007, 2008/2009 and 2010/2011) and were followed up at 2-year intervals were enrolled.

PRIMARY OUTCOME MEASURES

The association between RHR and risk of incident AF was evaluated using Cox proportional hazards regression and restricted cubic spline models.

RESULTS

Two hundred and forty-one individuals (0.52%) developed AF during 7.5 years of follow-up. After adjustment for age, sex, low-density and high-density lipoprotein, physical activity, alcohol consumption, smoking status, body mass index, mean systolic blood pressure, and history of diabetes and hypertension, the HRs were 2.32 (95% CI 1.45 to 3.72) for an RHR <60 beats/min and 2.80 (1.13 to 6.94) for an RHR ≥100 beats/min in comparison with an RHR of 70-80 beats/min. Restricted cubic spline models revealed a U-shaped relationship between RHR and incident AF.

CONCLUSION

These findings indicate that RHR and incident AF have a U-shaped relationship in the Chinese general population. Both lower and higher RHRs were associated with an increased risk of AF.

Effects of training adaption in endurance athletes with atrial fibrillation: protocol for a multicentre randomised controlled trial

Endurance athletes have a high prevalence of atrial fibrillation (AF), probably caused by exercise-induced cardiac remodelling. Athletes diagnosed with AF are often advised to reduce the intensity and amount of training but the efficacy of this intervention has not been investigated in endurance athletes with AF. Effects of detraining in endurance athletes with atrial fibrillation is a two-arm international multicentre randomised (1:1) controlled trial on the effects of a period of training adaption on AF burden in endurance athletes with paroxysmal AF. One-hundred-and-twenty endurance athletes diagnosed with paroxysmal AF are randomised to a 16-week period of intervention (training adaption) or a control group. We define training adaption as training with a heart rate (HR) not exceeding 75% of the individual maximum HR (HRmax), and total duration of weekly training not exceeding 80% of the self-reported average before the study. The control group is instructed to uphold training intensity including sessions with HR ≥85% of HRmax. AF burden is monitored with insertable cardiac monitors, and training intensity with HR chest-straps and connected sports watches. The primary endpoint, AF burden, will be calculated as the cumulative duration of all AF episodes lasting ≥30sec divided by total duration of monitoring. Secondary endpoints include number of AF episodes, adherence to training adaption, exercise capacity, AF symptoms and health-related quality of life, echocardiographic signs of cardiac remodelling and risk of cardiac arrhythmias related to upholding training intensity.

Trial registration number

NCT04991337.

Study protocol version

4.7 (Date 9 March 2023).

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.

Development and validation of a nomogram for predicting atrial fibrillation in patients with acute heart failure admitted to the ICU: a retrospective cohort study

INTRODUCTION

Acute heart failure is a serious condition. Atrial fibrillation is the most frequent arrhythmia in patients with acute heart failure. The occurrence of atrial fibrillation in heart failure patients worsens their prognosis and leads to a substantial increase in treatment costs. There is no tool that can effectively predict the onset of atrial fibrillation in patients with acute heart failure in the ICU currently.

MATERIALS AND METHODS

We retrospectively analyzed the MIMIC-IV database of patients admitted to the intensive care unit (ICU) for acute heart failure and who were initially sinus rhythm. Data on demographics, comorbidities, laboratory findings, vital signs, and treatment were extracted. The cohort was divided into a training set and a validation set. Variables selected by LASSO regression and multivariate logistic regression in the training set were used to develop a model for predicting the occurrence of atrial fibrillation in acute heart failure in the ICU. A nomogram was drawn and an online calculator was developed. The discrimination and calibration of the model was evaluated. The performance of the model was tested using the validation set.

RESULTS

This study included 2342 patients with acute heart failure, 646 of whom developed atrial fibrillation during their ICU stay. Using LASSO and multiple logistic regression, we selected six significant variables: age, prothrombin time, heart rate, use of vasoactive drugs within 24 h, Sequential Organ Failure Assessment (SOFA) score, and Acute Physiology Score (APS) III. The C-index of the model was 0.700 (95% CI 0.672-0.727) and 0.682 (95% CI 0.639-0.725) in the training and validation sets, respectively. The calibration curves also performed well in both sets.

CONCLUSION

We developed a simple and effective model for predicting atrial fibrillation in patients with acute heart failure in the ICU.

Risk of atrial fibrillation and stroke among older men exposed to prolonged endurance sport practice: a 10-year follow-up. The Birkebeiner Ageing Study and the Tromsø Study

Aims

Endurance sport practice is associated with a high prevalence of atrial fibrillation (AF), which increases the risk of stroke in the general population. However, stroke risk in endurance athletes with AF is sparsely investigated. Most studies have been limited by design and are largely restricted to younger and middle-aged populations. Thus, we aimed to investigate AF and stroke risk in older athletes exposed to prolonged endurance training.

Method

During a 10-year period, 505 male athletes aged ≥65 years frequently participating in a long-distance ski race were compared with 1867 men of the same age from the general population. The main exposure was endurance sport practice with self-reported AF and stroke as outcomes. Stroke risk was further examined by joint modelling of AF and endurance practice. Statistical analysis was conducted with a modified Poisson model.

Results

Athletes (median age: 68, range: 65–90) participated in a long-distance ski race over a median of 14 years (range: 1–53). Prevalence (28.5% vs 17.8%) and adjusted risk of AF (risk ratio (RR): 1.88, 95% CI: 1.49 to 2.37) were higher in athletes compared with non-athletes, whereas the prevalence (5.4% vs 9.7%) and risk of stroke were lower (RR: 0.60, 95% CI: 0.37 to 0.95). Compared with athletes without AF, risk of stroke was twofold in athletes (RR: 2.38, 95% CI: 1.08 to 5.24) and nearly fourfold in non-athletes (RR: 3.87, 95% CI: 1.98 to 7.57) with AF.

Conclusion

Although older male endurance athletes experienced an increased risk of AF, the long-term risk of stroke was substantially reduced compared with non-athletes.

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.

The Athlete's Heart-Challenges and Controversies: JACC Focus Seminar 4/4

Regular exercise promotes structural, functional, and electrical remodeling of the heart, often referred to as the "athlete's heart," with intense endurance sports being associated with the greatest degree of cardiac remodeling. However, the extremes of exercise-induced cardiac remodeling are potentially associated with uncommon side effects. Atrial fibrillation is more common among endurance athletes and there is speculation that other arrhythmias may also be more prevalent. It is yet to be determined whether this arrhythmic susceptibility is a result of extreme exercise remodeling, genetic predisposition, or other factors. Gender may have the greatest influence on the cardiac response to exercise, but there has been far too little research directed at understanding differences in the sportsman's vs sportswoman's heart. Here in part 4 of a 4-part seminar series, the controversies and ambiguities regarding the athlete's heart, and in particular, its arrhythmic predisposition, genetic, and gender influences are reviewed in depth.

The mediation function of resting heart rate in how physical activity improves all-cause mortality: Continuous and automatic measurement via cardiac implantable electronic devices

Background

Physical activity (PA) and resting heart rate (RHR) are connected with all-cause mortality. Moreover, there was an inverse correlation between PA and RHR. However, the causal relationship between PA, RHR, and long-term mortality has been rarely evaluated and quantified, particularly the mediation effect of RHR in the association between PA and all-cause mortality.

Objective

To describe the relationship between PA and RHR when consistently measured via cardiac implantable electronic devices (CIED) and further explore the mediation effect of PA on all-cause mortality through RHR.

Materials and methods

Patients who underwent CIED implantation and received remote home monitoring services were included. During the first 30–60 days after CIED implantation, daily PA and RHR were continuously measured and automatically transmitted by CIED. The primary endpoint was all-cause mortality. The multiple linear regression model was used to confirm the relationship between PA and RHR. The predictive values of both PA and RHR for all-cause mortality were assessed by multivariable Cox proportional hazards models. The causal mediation model was further established to verify and quantify the mediation effect of RHR in the association between PA and all-cause mortality.

Results

A total of 730 patients with CIED were included. The mean daily PA and RHR were 10.7 ± 5.7% and 61.3 ± 9.1 bpm, respectively. During a mean follow-up period of 55.8 months, 187 (26.5%) death was observed. A negative linear relationship between PA and RHR was demonstrated in the multiple regression model (β = −0.260; 95% CI: −0.377 to −0.143, p < 0.001). Multivariable Cox proportional hazards analysis showed that both lower levels of PA (HR = 0.907; 95% CI: 0.878–0.936, p < 0.001) and higher RHR (HR = 1.016; 95% CI: 1.001–1.032, P = 0.031) were independent risk factors of all-cause mortality. Causal mediation analysis further confirmed and quantified the mediation function of RHR in the process of PA improving all-cause mortality (mediation proportion = 3.9%; 95% CI: 0.2–10.0%, p = 0.036).

Conclusion

The effects of the higher level of PA on improving life prognosis may be partially mediated through RHR among patients with CIED. It indicates that changes in the autonomic nervous function during postoperative rehabilitation exercises should get more attention.

Cardiovascular magnetic resonance assessment of left atrial size and function in endurance athletes

Background: Left atrial (LA) dilatation is linked to cardiovascular disease and atrial fibrillation but its associations in athletes are unknown. The authors investigated whether aerobic fitness and clinical parameters are associated with LA dilatation and emptying fraction (EF) in endurance athletes. Materials & methods: 65 endurance athletes underwent cardiovascular magnetic resonance to assess LA size and function along with fitness assessment. 25 sedentary controls underwent an identical cardiovascular magnetic resonance protocol. Results: In athletes, LA volume index was elevated, while total and passive LAEFs were decreased versus sedentary controls. Increasing age and maximal oxygen uptake were associated with LA volume index. Only older age was associated with decreased total LAEF. Conclusion: LA dilatation in athletes is associated with increasing age and aerobic fitness rather than conventional cardiovascular risk factors.

Genetically predicted physical activity is associated with lower serum urate concentrations

BACKGROUND

Physical activity (PA) is considered to play an important role in the reduced gout risk. However, the epidemiology results are inconsistent and causality remains unclear.

OBJECTIVE

To investigate the causal relationship of PA with serum urate concentrations and gout risk by a bidirectional Mendelian randomization (MR) approach.

METHOD

Two genome-wide association studies (GWASs) from UK Biobank were used to identify instrumental variables for self-reported moderate-to-vigorous PA (including 377,234 European individuals), accelerometer-measured 'average acceleration' PA (including 91,084 European individuals) and accelerometer-measured overall PA (including 91,105 European individuals). The summary data for serum urate (including 110,347 European individuals) and gout (including 2,115 cases and 67,259 controls) were derived from GWAS of Global Urate Genetics Consortium. Moreover, reverse direction Mendelian randomization study was conducted. The inverse-variance weighted, weighted median, Mendelian randomization Egger regression, simple mode and weighted mode and Mendelian Randomization Pleiotropy RESidual Sum and Outlier were methods we performed.

RESULT

Genetic predisposition to accelerometer-measured 'average acceleration' PA [beta = -0.038; 95% confidence interval (CI) = -0.060,-0.015; P = 0.001] and accelerometer-measured overall PA (beta = -0.339; 95% CI = -0.522,-0.156; P = 2.8E-4) were significantly associated with decreased serum urate concentrations. Besides, there was no evidence supporting the causal association between PA and gout risk. In the reverse direction analysis, genetic predisposition to both urate and gout were not associated with PA being investigated.

CONCLUSIONS

In MR study, we found that PA may reduce serum urate concentrations but not the risk of gout. Moreover, serum urate concentrations and gout were not associated with PA.

Population Attributable Risks of Potential Modifiable Factors for Atrial Fibrillation in China: A National Survey

Background

There is an association between atrial fibrillation (AF) and overall mortality as well as mobility. It is not known, however, what the preventable burden of AF in China is. This study aims to identify what proportion of the burden of AF may be avoided by modifiable risk factors.

Methods

As part of the China National Stroke Screening and Prevention Project, 726,451 adults aged ≥40 years were enrolled in a representative cross-sectional study. The following seven factors have been categorized as modifiable risk factors for AF: body mass index, smoking, alcohol consumption, physical inactivity, hypertension, diabetes mellitus, and dyslipidemia. In order to calculate population-attributable risks (PARs), odds ratios (ORs) were calculated for selected risk factors.

Results

The crude ORs increased with age (ORs ranged from 1.92 to 4.02). A total of 18,736 cases of prevalent AF have been identified. The overall prevalence of AF was 2.6%. The crude ORs increased with age (ORs range 1.92–4.03). The adjusted ORs and the corresponding confidence intervals (CIs) for these seven modifiable factors were 1.16 (95% confidence interval [CI]: 1.12–1.19), 1.56 (95% CI: 1.49–1.62), 2.15 (95% CI: 2.02–2.28), 2.07 (95% CI: 2.01–2.14), 2.71 (95% CI: 2.62–2.79), 2.10 (95% CI: 2.02–2.19), 2.52 (95% CI: 2.44–2.60), and 3.32 (95% CI: 3.18–3.48), respectively. Accordingly, 59.3% of all cases of AF could be explained by having these modifiable risk factors, among which hypertension accounted for the greatest share.

Conclusion

In China, hypertension is the leading preventable cause of AF, and more than half of these cases can be prevented through improving those modifiable risk factors.

Mid-Life Cardiorespiratory Fitness, Obesity, and Risk of Atrial Fibrillation: The Cooper Center Longitudinal Study

Background

Lower cardiorespiratory fitness (CRF) and higher body mass index (BMI) are associated with a higher risk of myocardial infarction and heart failure. However, the independent contribution of these lifestyle factors to the risk of atrial fibrillation (AF) is less well established.

Objectives

The purpose of this study was to evaluation the association between midlife CRF, BMI, and risk of AF in older age.

Methods

This study included 18,493 participants without AF who underwent assessment of CRF (estimated using the maximal treadmill time) and BMI in middle age and had Medicare coverage after the age of 65 years. The association among midlife CRF, BMI, and risk of AF was assessed by fitting a proportional hazards intensity model to the failure time data with adjustment for potential confounders. The association between changes in CRF and BMI in middle age and the risk of AF was also assessed in the subset of participants with repeat CRF assessments.

Results

Among 18,493 participants (79% men), a higher midlife BMI was significantly associated with a higher risk of AF independent of CRF levels and other potential confounders (hazard ratio per 1-kg/m2: 1.05; 95% confidence interval: 1.03-1.06). Lower midlife CRF was also associated with higher risk of AF (hazard ratio per 1 MET higher CRF: 0.98; 95% confidence interval: 0.96-0.99). However, this association was attenuated and not significant after further adjustment for BMI. Change in CRF on follow-up was also not associated with the risk of AF after adjustment for other confounders.

Conclusions

The association between low fitness and AF was primarily driven by differences in BMI. In contrast, obesity was independently associated with excess AF risk.

Resting heart rate and incident atrial fibrillation: A stratified Mendelian randomization in the AFGen consortium

Background

Both elevated and low resting heart rates are associated with atrial fibrillation (AF), suggesting a U-shaped relationship. However, evidence for a U-shaped causal association between genetically-determined resting heart rate and incident AF is limited. We investigated potential directional changes of the causal association between genetically-determined resting heart rate and incident AF.

Method and results

Seven cohorts of the AFGen consortium contributed data to this meta-analysis. All participants were of European ancestry with known AF status, genotype information, and a heart rate measurement from a baseline electrocardiogram (ECG). Three strata of instrumental variable-free resting heart rate were used to assess possible non-linear associations between genetically-determined resting heart rate and the logarithm of the incident AF hazard rate: <65; 65–75; and >75 beats per minute (bpm). Mendelian randomization analyses using a weighted resting heart rate polygenic risk score were performed for each stratum.

We studied 38,981 individuals (mean age 59±10 years, 54% women) with a mean resting heart rate of 67±11 bpm. During a mean follow-up of 13±5 years, 4,779 (12%) individuals developed AF. A U-shaped association between the resting heart rate and the incident AF-hazard ratio was observed. Genetically-determined resting heart rate was inversely associated with incident AF for instrumental variable-free resting heart rates below 65 bpm (hazard ratio for genetically-determined resting heart rate, 0.96; 95% confidence interval, 0.94–0.99; p = 0.01). Genetically-determined resting heart rate was not associated with incident AF in the other two strata.

Conclusions

For resting heart rates below 65 bpm, our results support an inverse causal association between genetically-determined resting heart rate and incident AF.

Blood pressure measurements during treadmill exercise testing and the risk for the future development of atrial fibrillation

Hypertension is a well-established risk factor for the onset and progression of atrial fibrillation (AF). Blood pressure (BP) measurements during routine exercise stress testing (EST) may identify subjects at increased risk for developing AF. We performed a retrospective analysis of treadmill EST carried out using the Bruce protocol in patients aged ≥40 years without a history of AF (n = 17,617; 42% women). BP was measured at rest, peak exercise, and 2-min recovery and analyzed for its association with the risk for developing AF. During a mean follow-up of 7 years, AF was documented in 4.5% of the patients. The incidence rate of AF per 1000 person-years increased with the rise in CHA₂DS₂VASc scores (3.26 for a Score=0 to 19.78 for scores ≥6). In a multivariate analysis, adjusting for risk score components and exercise capacity, systolic BP measurements taken at rest (≥130 vs. ≤110 mmHg), peak exercise (>170 vs. ≤150 mmHg), and recovery (>150 vs. ≤130 mmHg) were associated with an increased risk for AF: the hazard ratios (HRs) were 1.56 (95% CI, 1.30-1.87), 1.21 (1.01-1.45), and 1.33 (1.10-1.62), respectively. Similarly, diastolic BP measurements taken at rest (≥90 vs. <80 mmHg), peak exercise (≥100 vs. <90 mmHg), and recovery (>90 vs. ≤80 mmHg) were associated with an increased risk for AF: the HRs were 1.80 (1.36-2.38), 2.08 (1.28-3.37), and 1.56 (0.81-3.02), respectively. The association of exercise BP with AF was further observed when the BPs were analyzed as continuous variables and in subjects without a baseline diagnosis of hypertension. In conclusion, systolic and diastolic BP taken at the rest, peak exercise and recovery phases of EST may provide independent predictive information regarding future risk for developing AF.

Rationale and design of the PROspective ATHletic Heart (Pro@Heart) study: long-term assessment of the determinants of cardiac remodelling and its clinical consequences in endurance athletes

Background

Exercise-induced cardiac remodelling (EICR) results from the structural, functional and electrical adaptations to exercise. Despite similar sports participation, EICR varies and some athletes develop phenotypic features that overlap with cardiomyopathies. Training load and genotype may explain some of the variation; however, exercise ‘dose’ has lacked rigorous quantification. Few have investigated the association between EICR and genotype.

Objectives

(1) To identify the impact of training load and genotype on the variance of EICR in elite endurance athletes and (2) determine how EICR and its determinants are associated with physical performance, health benefits and cardiac pathology.

Methods

The Pro@Heart study is a multicentre prospective cohort trial. Three hundred elite endurance athletes aged 14–23 years will have comprehensive cardiovascular phenotyping using echocardiography, cardiac MRI, 12-lead ECG, exercise-ECG and 24-hour-Holter monitoring. Genotype will be determined using a custom cardiomyopathy gene panel and high-density single-nucleotide polymorphism arrays. Follow-up will include online tracking of training load. Cardiac phenotyping will be repeated at 2, 5, 10 and 20 years.

Results

The primary endpoint of the Pro@Heart study is the association of EICR with both training load and genotype. The latter will include rare variants in cardiomyopathy-associated genes and polygenic risk scores for cardiovascular traits. Secondary endpoints are the incidence of atrial and ventricular arrhythmias, physical performance and health benefits and their association with training load and genotype.

Conclusion

The Pro@Heart study is the first long-term cohort study to assess the impact of training load and genotype on EICR.

Trial registration number

NCT05164328; ACTRN12618000716268.

Associations between physical activity, left atrial size and incident atrial fibrillation: the Tromsø Study 1994-2016

AIMS

Left atrial (LA) enlargement is an independent risk factor for atrial fibrillation (AF). Interestingly, some athletes have increased risk of AF, which may be linked to LA enlargement; however, little is known about the relationship between LA enlargement and AF risk at moderate-level physical activity (PA). We aimed to explore the associations between PA, LA size and risk of incident AF, and if PA can attenuate the risk of AF with LA enlargement.

METHODS

This prospective study followed 2479 participants (52.4% female), free from known cardiac pathology, for median 20.2 years. Participants were followed up for hospital-diagnosed AF, confirmed by electrocardiography, from 1994-95 through 2016. At baseline, LA size was evaluated by anteroposterior LA diameter, and PA was self-reported by questionnaire.

RESULTS

We observed a U-shaped relationship between PA and AF, and moderately active had 32% lower AF risk than inactive (HRadjusted 0.68, 95% CI 0.50 to 0.93). Participants with LA enlargement had 38% higher AF risk compared with participants with normal LA size (HRadjusted 1.38, 95% CI 1.12 to 1.69). However, the increased AF risk with LA enlargement was attenuated by PA; compared with inactive participants with LA enlargement, the AF risk was 45% lower among active with LA enlargement (HRadjusted 0.55, 95% CI 0.39 to 0.79). AF risk in active participants with LA enlargement did not differ from active with normal LA size. These patterns were observed in both men and women, and in participants over/under 65 years.

CONCLUSION

Moderate PA was associated with reduced AF risk, and PA attenuated the increased risk of AF with LA enlargement in both men and women and all age groups.

Recommendations for participation in leisure-time physical activity and competitive sports in patients with arrhythmias and potentially arrhythmogenic conditions: Part 1: Supraventricular arrhythmias. A position statement of the Section of Sports Cardiology and Exercise from the European Association of Preventive Cardiology (EAPC) and the European Heart Rhythm Association (EHRA), both associations of the European Society of Cardiology

Symptoms attributable to arrhythmias are frequently encountered in clinical practice. Cardiologists and sport physicians are required to identify high-risk individuals harbouring such conditions and provide appropriate advice regarding participation in regular exercise programmes and competitive sport. The three aspects that need to be considered are: (a) the risk of life-threatening arrhythmias by participating in sports; (b) control of symptoms due to arrhythmias that are not life-threatening but may hamper performance and/or reduce the quality of life; and (c) the impact of sports on the natural progression of the underlying arrhythmogenic condition. In many cases, there is no unequivocal answer to each aspect and therefore an open discussion with the athlete is necessary, in order to reach a balanced decision. In 2006 the Sports Cardiology and Exercise Section of the European Association of Preventive Cardiology published recommendations for participation in leisure-time physical activity and competitive sport in individuals with arrhythmias and potentially arrhythmogenic conditions. More than a decade on, these recommendations are partly obsolete given the evolving knowledge of the diagnosis, management and treatment of these conditions. The present document presents a combined effort by the Sports Cardiology and Exercise Section of the European Association of Preventive Cardiology and the European Heart Rhythm Association to offer a comprehensive overview of the most updated recommendations for practising cardiologists and sport physicians managing athletes with supraventricular arrhythmias, and provides pragmatic advice for safe participation in recreational physical activities, as well as competitive sport at amateur and professional level. A companion text on recommendations in athletes with ventricular arrhythmias, inherited arrhythmogenic conditions, pacemakers and implantable defibrillators is published as Part 2 in Europace.

Exercise and the Female Heart

Female participation in sport has increased sharply during the last few decades, and for the third straight Olympic Games, there were more women than men on the US roster for the 2020 Tokyo Games. Given this, an understanding of the differences between men and women with respect to exercise-induced cardiac remodeling is critical for those caring for female athletes. Recent studies have provided insight into female-specific cardiac remodeling and have enhanced our understanding on the upper limits of cardiac remodeling in female athletes and how these adaptations compare with sedentary females, male athletes, and cardiomyopathies. Female athletes display fewer signs of adaptive remodeling on ECG compared with male athletes. Structurally, male athletes have larger absolute cardiac dimensions, but female athletes have similar or larger chamber size when adjusted for body size. Female athletes have a lower incidence of sudden cardiac arrest or death compared with male athletes in the early competitive years (high school, college, and professional) and in the masters athlete years. In addition, female athletes are less likely to have coronary disease and atrial fibrillation compared with male athletes. Data on longevity indicate that female athletes live longer than their sedentary counterparts. Unlike men, there has been no convincing association of extreme exercise and cardiovascular disease in longer-term endurance female athletes. The underlying mechanisms of these sex-based differences are not very well understood, and future studies are warranted to better understand the mechanisms of cardiac adaptation in female athletes.

Increased resting heart rate and glucose metabolism in a community population

Objective

Resting heart rate (RHR) independently predicts cardiovascular death. Increased RHR is related to chronic diseases, but community-based studies are rare. We investigated this population and factors related to RHR.

Methods

In total, 374 participants underwent medical examinations from March 2019 to December 2019. Participants were divided into groups with low RHR (LRHR; <65 beats/minute) and high RHR (HRHR; ≥65 beats/minute). RHR was judged using resting electrocardiogram at physical examination. We conducted laboratory examinations, including glycosylated hemoglobin (HbA1c), fasting plasma glucose (FPG), and blood lipids, among participants with chronic diseases. We used Cox proportional risk regression and multivariate analyses for the following covariates: previous chronic diseases, body mass index (BMI), smoking, blood lipids, and FPG.

Results

The incidence of type 2 diabetes mellitus (T2DM) and HbA1c values were both significantly higher in the HRHR group than in the LRHR group. Spearman correlation analysis showed RHR had a positive correlation with low-density lipoprotein, BMI, FPG, and HbA1c (r = 0.104574, 0.117266, 0.116041, and 0.311761, respectively). Multiple linear regression analysis showed age, hypertension, T2DM, and HbA1c were factors influencing RHR.

Conclusion

RHR showed strong correlation with T2DM and HbA1c in our community population, suggesting that RHR may be a risk factor for cardiovascular disease.

Exercise Training: The Holistic Approach in Cardiovascular Prevention

Nowadays, there are robust clinical and pathophysiological evidence supporting the beneficial effects of physical activity on cardiovascular (CV) system. Thus, the physical activity is considered a key strategy for CV prevention. In fact, exercise training exerts favourable effects on all risk factors for CV diseases (i.e. essential hypertension, type 2 diabetes mellitus, hypercholesterolemia, obesity, metabolic syndrome, etc…). In addition, all training modalities such as the aerobic (continuous walking, jogging, cycling, etc.) or resistance exercise (weights), as well as the leisure-time physical activity (recreational walking, gardening, etc) prevent the development of the major CV risk factors, or delay the progression of target organ damage improving cardio-metabolic risk. Exercise training is also the core component of all cardiac rehabilitation programs that have demonstrated to improve the quality of life and to reduce morbidity in patients with CV diseases, mostly in patients with coronary artery diseases. Finally, it is still debated whether or not exercise training can influence the occurrence of atrial and ventricular arrhythmias. In this regard, there is some evidence that exercise training is protective predominantly for atrial arrhythmias, reducing the incidence of atrial fibrillation. In conclusion, the salutary effects evoked by physical acitvity are useful in primary and secondary CV prevention.

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.