Arrhythmias and structural remodeling in lifelong and retired master endurance athletes

BACKGROUND

A greater prevalence of arrhythmias has been described in endurance athletes, but it remains unclear whether this risk persists after detraining. We aimed to evaluate the prevalence of arrhythmias and their relationship with cardiac remodeling in lifelong and retired master endurance athletes compared to non-athletic controls.

METHODS

We performed a cross-sectional analysis of observational studies that used echocardiography and cardiac magnetic resonance to detail cardiac structure and function, and Holter monitors to identify atrial and ventricular arrhythmias in 185 endurance athletes and 81 non-athletic controls aged ≥40 years. Athletes were categorized as active lifelong (n = 144) or retired (n = 41) based on hours per week of high-intensity endurance exercise within 5 years of enrollment and validated by percentage of predicted maximal oxygen consumption (VO2max). Athletes with overt cardiomyopathies, channelopathies, pre-excitation, and/or myocardial infarction were excluded.

RESULTS

Lifelong athletes (median age = 55 years (interquartile range (IQR): 46-62), 79% male) were significantly fitter than retired athletes (median age = 66 years (IQR: 58-71), 95% male) and controls (median age = 53 years (IQR: 48-60), 96% male), respectively (predicted VO2max: 131% ± 18% vs. 99% ± 14% vs. 98% ± 15%, p < 0.001). Compared to controls, athletes in our cohort had a higher prevalence of atrial fibrillation ((AF): 32% vs. 0%, p < 0.001) and non-sustained ventricular tachycardia ((NSVT): 9% vs. 1%, p < 0.001). There was no difference in prevalence of any arrhythmia between lifelong and retired athletes. Lifelong athletes had larger ventricular volumes than retired athletes, who had ventricular volumes similar to controls (left ventricular end-diastolic volume indexed to body surface area (LVEDVi): 101 ± 20 mL/m2vs. 86 ± 16 mL/m2vs. 94 ± 18 mL/m2, p < 0.001; right ventricular end-diastolic volume indexed to body surface area (RVEDVi): 117 ± 23 mL/m2vs. 101 ± 19 mL/m2vs. 100 ± 19 mL/m2, p < 0.001). Athletes had more scar (40% vs. 18%, p = 0.002) and larger left atria (median volume = 45 mL/m2 (IQR: 38-52) vs. 31 mL/m2 (IQR: 25-38), p < 0.001) than controls, with no difference in atrial volumes and non-ischaemic scar between the athlete groups.

CONCLUSION

Master endurance athletes have a higher prevalence of AF and NSVT than non-athletic controls. Whereas ventricular remodeling tends to reverse with detraining, the propensity to arrhythmias persists regardless of whether they are actively exercising or retired.

Long-term left atrial adaptations to reduced training load in former elite athletes: a long-term follow-up longitudinal observational study

Objective

Our objective was to evaluate the effects of long-term reduced training on the left atrium (LA) in elite endurance athletes and to elucidate sex-specific differences in LA detraining patterns.

Methods

In this long-term longitudinal echocardiographic study of 50 active elite endurance athletes a follow-up examination was performed 7 years after retirement from the elite programme. All echocardiographic measurements were indexed for body surface area. We analysed the changes between baseline and follow-up measures using analysis of covariance models adjusted for baseline level, sex and enrolment age as covariates. Results are reported as least squares means with two-sided 95% CIs.

Results

LA enlargement (left atrial maximum volume index) remained unchanged from baseline (change from baseline: 1.4mL/m2, 95% CI: -0.7 to 3.5 mL/m2) despite significant reductions in VO2max (change from baseline: -864mL/min, 95% CI: -1091 to -637 mL/min). In contrast, left ventricular (LV) end-diastolic volume was reduced (change from baseline: -8mL/m2, 95% CI: -11 to -5 mL/m2), consistent with reduced VO2max. LA contraction strain was increased (change from baseline: 1.4%, 95% CI: 0.4% to 2.5%), while LV filling pressure increased (E/e' change from baseline: 0.4, 95% CI: 0.1 to 0.7).

Conclusions

7 years of reduced training does not reverse exercise-induced LA enlargement in former elite endurance athletes. LA contractile function improved with higher LV filling pressure, suggesting that age-related LV pressure increases may contribute to chronic LA dilation, though irreversible adaptations like fibrosis cannot be ruled out.

Trial registration number

NCT05555849.

Atrial Fibrillation in Elite Athletes: A Comprehensive Review of the Literature

Although the benefits of exercise training have been shown repeatedly in many studies, its relationship with the occurrence of atrial fibrillation (AF) in competitive athletes still remains controversial. In the present review, we sought to demonstrate a comprehensive report of the incidence, pathophysiology, and therapeutic approaches to AF in elite athletes. A 2 to 10 times higher frequency of AF has been shown in many studies in high-intensity endurance athletes compared to individuals who do not exercise. Moreover, a U-shaped relationship between male elite athletes and AF is demonstrated through this finding, while the type and the years of physical activity seem to relate to AF development. A strong correlation seems to exist among the type of exercise (endurance sports), age (>55 years), gender (males), and the time of exercise training, all contributing to an increased risk of AF. The pathophysiology of AF still remains unclear; however, several theories suggest that complex mechanisms are involved, such as bi-atrial dilatation, pulmonary vein stretching, cardiac inflammation, fibrosis, and increased vagal tone. Elite athletes with AF require a comprehensive clinical evaluation and risk factor optimization, similar to the approach taken for nonathletes. Although anticoagulation and rate or rhythm control are cornerstones of AF management, there are still no specific guidelines for elite athletes.

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.

Characterizing the influence of cardiorespiratory fitness on left atrial size and function in the general population

Increased left atrial (LA) size and reduced LA function have been associated with heart failure and atrial fibrillation (AF) in at-risk populations. However, atrial remodeling has also been associated with exercise training and the relationship between fitness, LA size, and function has not been defined across the fitness spectrum. In a cross-sectional study of 559 ostensibly healthy participants, comprising 304 males (mean age, 46 ± 20 yr) and 255 females (mean age, 47 ± 15 yr), we sought to define the relationship between cardiorespiratory fitness (CRF), LA size, and function. We also aimed to interrogate sex differences in atrial factors influencing CRF. Echocardiographic measures included biplane measures of LA volumes indexed to body surface area (LAVi) and atrial deformation using two-dimensional speckle tracking. CRF was measured as peak oxygen consumption (V̇o2peak) during cardiopulmonary exercise testing (CPET). Using multivariable regression, age, sex, weight, and LAVi (P < 0.001 for all) predicted V̇o2peak (P < 0.001, R2 = 0.66 for combined model). After accounting for these variables, heart rate reserve added strength to the model (P < 0.001, R2 = 0.74) but LA strain parameters did not predict V̇o2peak. These findings add important nuance to the perception that LA size is a marker of cardiac pathology. LA size should be considered in the context of fitness, and it is likely that the adverse prognostic associations of increased LA size may be confined to those with LA enlargement and low fitness.NEW & NOTEWORTHY Left atrial (LA) structure better predicts cardiorespiratory fitness (CRF) than LA function. LA function adds little statistical value to predictive models of peak oxygen uptake (V̇o2peak) in healthy individuals, suggesting limited discriminatory for CRF once LA size is factored. In the wider population of ostensibly healthy individuals, the association between increased LA volume and higher CRF provides an important counter to the association between atrial enlargement and heart failure symptoms in those with cardiac pathology.

The effects of daily dose of intense exercise on cardiac responses and atrial fibrillation

Atrial fibrillation (AF) is a supraventricular tachyarrhythmia that is strongly associated with cardiovascular (CV) disease and sedentary lifestyles. Despite the benefits of exercise on overall health, AF incidence in high-level endurance athletes rivals that of CV disease patients, suggesting a J-shaped relationship with AF. To investigate the dependence of AF vulnerability on exercise, we varied daily swim durations (120, 180 or 240 min day-1 ) in 7-week-old male CD1 mice. We assessed mice after performing equivalent amounts of cumulative work during swimming (i.e. ∼700 L O2  kg-1 ), as determined from O2 consumption rates (V ̇ O 2 ${\dot V_{{{\mathrm{O}}_2}}}$ ). The meanV ̇ O 2 ${\dot V_{{{\mathrm{O}}_2}}}$ during exercise increased progressively throughout the training period and was indistinguishable between the swim groups. Consistent with similar improvements in aerobic conditioning induced by swimming, skeletal muscle mitochondria content increased (P = 0.027) indistinguishably between exercise groups. Physiological ventricular remodelling, characterized by mild hypertrophy and left ventricular dilatation, was also similar between exercised mice without evidence of ventricular arrhythmia inducibility. By contrast, prolongation of daily swim durations caused progressive and vagal-dependent heart rate reductions (P = 0.008), as well as increased (P = 0.005) AF vulnerability. As expected, vagal inhibition prolonged (P = 0.013) atrial refractoriness, leading to reduced AF vulnerability, although still inducible in the 180 and 240 min swim groups. Accordingly, daily swim dose progressively increased atrial hypertrophy (P = 0.003), fibrosis (P < 0.001) and macrophage accumulation (P = 0.006) without differentially affecting the ventricular tissue properties. Thus, increasing daily exercise duration drives progressively adverse atrial-specific remodelling and vagal-dependent AF vulnerability despite robust and beneficial aerobic conditioning and physiological remodelling of ventricles and skeletal muscle. KEY POINTS: Previous studies have suggested that a J-shaped dose-response relationship exists between physical activity and cardiovascular health outcomes, with moderate exercise providing protection against many cardiovascular disease conditions, whereas chronic endurance exercise can promote atrial fibrillation (AF). We found that AF vulnerability increased alongside elevated atrial hypertrophy, fibrosis and inflammation as daily swim exercise durations in mice were prolonged (i.e. ≥180 min day-1 for 6 weeks). The MET-h week-1 (based on O2  measurements during swimming) needed to induce increased AF vulnerability mirrored the levels linked to AF in athletes. These adverse atria effects associated with excessive daily exercise occurred despite improved aerobic conditioning, skeletal muscle adaptation and physiological ventricular remodelling. We suggest that atrial-specific changes observed with exercise arise from excessive elevations in venous filling pressures during prolonged exercise bouts, which we argue has implications for all AF patients because elevated atrial pressures occur in most cardiovascular disease conditions as well as ageing which are linked to AF.

Standardised Exercise Prescription for Patients with Chronic Coronary Syndrome and/or Heart Failure: A Consensus Statement from the EXPERT Working Group

Whereas exercise training, as part of multidisciplinary rehabilitation, is a key component in the management of patients with chronic coronary syndrome (CCS) and/or congestive heart failure (CHF), physicians and exercise professionals disagree among themselves on the type and characteristics of the exercise to be prescribed to these patients, and the exercise prescriptions are not consistent with the international guidelines. This impacts the efficacy and quality of the intervention of rehabilitation. To overcome these barriers, a digital training and decision support system [i.e. EXercise Prescription in Everyday practice & Rehabilitative Training (EXPERT) tool], i.e. a stepwise aid to exercise prescription in patients with CCS and/or CHF, affected by concomitant risk factors and comorbidities, in the setting of multidisciplinary rehabilitation, was developed. The EXPERT working group members reviewed the literature and formulated exercise recommendations (exercise training intensity, frequency, volume, type, session and programme duration) and safety precautions for CCS and/or CHF (including heart transplantation). Also, highly prevalent comorbidities (e.g. peripheral arterial disease) or cardiac devices (e.g. pacemaker, implanted cardioverter defibrillator, left-ventricular assist device) were considered, as well as indications for the in-hospital phase (e.g. after coronary revascularisation or hospitalisation for CHF). The contributions of physical fitness, medications and adverse events during exercise testing were also considered. The EXPERT tool was developed on the basis of this evidence. In this paper, the exercise prescriptions for patients with CCS and/or CHF formulated for the EXPERT tool are presented. Finally, to demonstrate how the EXPERT tool proposes exercise prescriptions in patients with CCS and/or CHF with different combinations of CVD risk factors, three patient cases with solutions are presented.

Long-Term Sports Practice and Atrial Fibrillation: An Updated Review of a Complex Relationship

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice, and it is an enormous burden worldwide because of its high morbidity, disability and mortality. It is generally acknowledged that physical activity (PA) is strongly associated with a significant reduction in the risk of cardiovascular (CV) disease and all-cause mortality. Moreover, it has been observed that moderate and regular physical activity has the potential to reduce the risk of AF, in addition to improving overall well-being. Nevertheless, some studies have associated intense physical activity with an increased risk of AF. This paper aims to review the main related literature to investigate the association between PA and AF incidence and draw pathophysiological and epidemiological conclusions.

Körperliche Aktivität/Sport – Auswirkung unterschiedlicher Trainingsformen und -intensitäten auf das Herz

„Das Sport-Paradox“ beschreibt die Ambivalenz zwischen einerseits klar evidenzbasierten gesundheitlichen Vorteilen des regelmäßigen Sporttreibens und andererseits der ebenso unumstrittenen gesundheitlichen Nachteile, die der Sport mit sich bringen kann.

Mindestens 30 Minuten moderate körperliche Belastung (bei Kindern 60 Minuten), an mindesten 5 Tagen pro Woche sind notwendig, um die gesundheitlichen Vorteile zu erreichen. Das Herz-Kreislaufsystem unterliegt dabei, bei regelmäßigem intensiven, vor allem dynamischem Ausdauertraining physiologischen Adapationen, welche von verschiedenen weiteren Faktoren abhängen. Während die exzentrische Hypertrophie des linken Ventrikels, in der Regel, reversibel ist, zeigt sich die „right ventricular fatigue“, bei entsprechender genetischer Belastung teilweise progredient. Dilatation und Fibrosierung der Vorhöfe führen zu einem erhöhten Risiko für ein Vorhofflimmern und auch eine häufig klinisch asymptomatische Dilatation der Aorta oder eine durch chronischen Stress bedingte Koronarsklerose können potenziell schwerwiegende Folgen mit sich bringen. Umso entscheidender sind individuelle und spezifische Trainingsempfehlungen.

[Atrial fibrillation in athletes : Prevalence, diagnosis, and treatment]

BACKGROUND

The incidence of atrial fibrillation (AF) is increased by an average of approximately 2.5-fold in recreational and elite athletes, depending on the intensity of exercise. It is, however, difficult to determine the exact duration or intensity of exercise that increases the risk of AF. The pathophysiological mechanisms of AF in athletes are a combination of pulmonary vein ectopy as a trigger, myocardial changes such as fibrosis and remodeling processes, and modulators such as changes in the autonomic nervous system. However, gastroesophageal reflux also seems to play an important role.

MATERIAL AND METHODS

The classic AF diagnosis is performed by means of 12-lead or Holter ECG; arrhythmia recordings via chest belts and pulse watches are not sufficient for the differentiation of the arrhythmia. However, wearables with the capability of ECG recording can also be used for AF screening. The first AF documentation in an athlete should be followed by cessation of physical exercise and initiation of detailed cardiac diagnostics. Thereafter, evaluation of oral anticoagulation is important. Long-term antiarrhythmic therapies are usually not tolerated or desired by athletes. Thus, valuable therapeutic options are either a "pill in the pocket" therapy with antiarrhythmic drugs or catheter ablation.

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.

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.

Day-to-day measurement of physical activity and risk of atrial fibrillation

Aims 

The aim of this study was to investigate the association between within-individual changes in physical activity and onset of atrial fibrillation (AF).

Methods and results 

A total of 1410 participants from the general population (46.2% women, mean age 74.7 ± 4.1 years) with risk factors but with no prior AF diagnosis underwent continuous monitoring for AF episodes along with daily accelerometric assessment of physical activity using an implantable loop recorder during ≈3.5 years. The combined duration of monitoring was ≈1.6 million days, where 10 851 AF episodes lasting ≥60 min were detected in 361 participants (25.6%) with a median of 5 episodes (2, 25) each. The median daily physical activity was 112 (66, 168) min/day. A dynamic parameter describing within-individual changes in daily physical activity, i.e. average daily activity in the last week compared to the previous 100 days, was computed and used to model the onset of AF. A 1-h decrease in average daily physical activity was associated with AF onset the next day [odds ratio 1.24 (1.18–1.31)]. This effect was modified by overall level of activity (P < 0.001 for interaction), and the signal was strongest in the tertile of participants with lowest activity overall [low: 1.62 (1.41–1.86), mid: 1.27 (1.16–1.39), and high: 1.10 (1.01–1.19)].

Conclusions 

Within-individual changes in physical activity are associated with the onset of AF episodes as detected by continuous monitoring in a high-risk population. For each person, a 1-h decrease in daily physical activity during the last week increased the odds of AF onset the next day by ≈25%, while the strongest association was seen in the group with the lowest activity overall.

Clinical Trial Registration

ClinicalTrials.gov, identifier: NCT02036450.

Risk of atrial fibrillation in athletes: a systematic review and meta-analysis

OBJECTIVE

A systematic review, meta-analysis and meta-regression were performed on selected studies to investigate the incidence of atrial fibrillation (AF) among athletes compared with non-athlete controls.

DESIGN

Meta-analysis with heterogeneity analysis and subsequent meta-regression to model covariates were performed. The mode of exercise (endurance and mixed sports) and age were the a priori determined covariates.

DATA SOURCES

PubMed, MEDLINE, Science Direct, SPORTDiscus and the Cochrane library were searched.

ELIGIBILITY CRITERIA

Research articles published after 1990 and before 2 December 2020 were included if they reported the number of AF cases in athletes with non-athlete (physically active or inactive) control groups, were case-control or cohort studies and if data allowed calculation of OR.

RESULTS

The risk of developing AF was significantly higher in athletes than in non-athlete controls (OR: 2.46; 95% CI 1.73 to 3.51; p<0.001, Z=4.97). Mode of exercise and risk of AF were moderately correlated (B=0.1259, p=0.0193), with mixed sport conferring a greater risk of AF than endurance sport (B=-0.5476, p=0.0204). Younger (<55 years) athletes were significantly more likely to develop AF compared with older (≥55 years) athletes (B=-0.02293, p<0.001).

CONCLUSION

Athletes have a significantly greater likelihood of developing AF compared with non-athlete controls, with those participating in mixed sport and younger athletes at the greatest risk. Future studies of AF prevalence in athletes according to specific exercise dose parameters, including training and competition history, may aid further in delineating those at risk.

Differing mechanisms of atrial fibrillation in athletes and non-athletes: alterations in atrial structure and function

AIMS

Atrial fibrillation (AF) is more common in athletes and may be associated with adverse left atrial (LA) remodelling. We compared LA structure and function in athletes and non-athletes with and without AF.

METHODS AND RESULTS

Individuals (144) were recruited from four groups (each n = 36): (i) endurance athletes with paroxysmal AF, (ii) endurance athletes without AF, (iii) non-athletes with paroxysmal AF, and (iv) non-athletic healthy controls. Detailed echocardiograms were performed. Athletes had 35% larger LA volumes and 51% larger left ventricular (LV) volumes vs. non-athletes. Non-athletes with AF had increased LA size compared with controls. LA/LV volume ratios were similar in both athlete groups and non-athlete controls, but LA volumes were differentially increased in non-athletes with AF. Diastolic function was impaired in non-athletes with AF vs. non-athletes without, while athletes with and without AF had normal diastolic function. Compared with non-AF athletes, athletes with AF had increased LA minimum volumes (22.6 ± 5.6 vs. 19.2 ± 6.7 mL/m2, P = 0.033), with reduced LA emptying fraction (0.49 ± 0.06 vs. 0.55 ± 0.12, P = 0.02), and LA expansion index (1.0 ± 0.3 vs. 1.2 ± 0.5, P = 0.03). LA reservoir and contractile strain were decreased in athletes and similar to non-athletes with AF.

CONCLUSION

Functional associations differed between athletes and non-athletes with AF, suggesting different pathophysiological mechanisms. Diastolic dysfunction and reduced strain defined non-athletes with AF. Athletes had low atrial strain and those with AF had enlarged LA volumes and reduced atrial emptying, but preserved LV diastolic parameters. Thus, AF in athletes may be triggered by an atrial myopathy from exercise-induced haemodynamic stretch consequent to increased cardiac output.

Atrial size and sports. A great training for a greater left atrium: how much is too much?

Athlete's heart results from physiological adaptations to the increased demands of exercise, and left atrial (LA) enlargement (LAE) is a fundamental component. However, LAE occurs in certain pathological conditions and it might represent a diagnostic challenge in athletes. LA volume index (LAVi) by echo is a convenient diagnostic tool for LAE identification. We hypothesized that accumulated lifetime training thousand hours (LTH) would have a main role in LAE. Therefore, our aim was to assess the association between LTH, LAVi and LAE in athletes. Young and middle-aged males with different training levels were included and grouped as recreational (REa, n = 30), competitive (COa, n = 169) and elite (ELa, n = 80) athletes for LTH calculation and echo assessment. LA dimensions resulted greater in ELa when compared to other groups (p < 0.001). LAVi correlated stronger with LTH than with age (p < 0.001). Polynomial regression analysis showed a non-linear, almost triphasic, effect of cumulative training on LA size (p < 0.02). Multivariate logistic regression, including LTH, age, body surface area, systolic blood pressure and other explanatory variables to predict LAE, showed LTH as the sole significant factor [OR 1.45 (CI 1.1-1.92), p < 0.008]. ROC analysis found an optimal cut off point of 3.6 LTH for LAE identification (AUC = 0.84, p < 0.001. RR = 5.65, p < 0.001). We conclude that LAE associates with LTH more than with other clinical parameters, and with less impact at higher amounts of LTH. Lifetime training greater than 3600 hours increases the probability of finding LAE in athletes. Future research should provide more insights and implications of these findings.

Prospective long-term follow-up analysis of the cardiovascular system in marathon runners: study design of the Pro-MagIC study

Introduction

Prolonged strenuous exercise training may result in structural, functional and electrical cardiac remodelling, as well as vascular and myocardial injuries. However, the extent to which high-volume, intense exercise is associated with arrhythmias, myocardial fibrosis, coronary heart disease and pathological alterations of the vasculature remains unknown. In addition, there is no clear consensus on the clinical significance of these exercise-induced changes. Previous studies typically used cross-sectional designs and examined exercise-induced cardiovascular changes in small cohorts of athletes for up to 3–7 days of recovery. Long-term longitudinal studies investigating cardiovascular changes induced by prolonged strenuous exercise in large cohorts of athletes are needed to improve scientific understanding in this area.

Methods and analysis

In this prospective observational monocenter study, 277 participants of the Beer, Marathon, Genetics, Inflammation and the Cardiovascular System (Be-MaGIC) study (ClinicalTrials.gov: NCT00933218) will be invited to participate in this 10-year follow-up study. A minimum target sample size of 130 participants will be included in the study. Participating athletes will be examined via the following: anthropometry, resting electrocardiography and echocardiography, blood sampling, retinal vessel diameters, carotid sonography and cardiopulmonary exercise testing, including exercise electrocardiography.

Discussion

This longitudinal study will provide comprehensive data on physiological changes in the cardiovascular system and the development of pathologies after a 10-year period of prolonged and strenuous endurance exercise. Since the participants will have engaged in a wide range of training loads and competitive race events, this study will provide useful risk factor determinants and training load cut-off values. The primary endpoint is the association between the exercise-induced increase in cardiac troponin during the Munich marathon 2009 and the decline in right ventricular ejection fraction over the next 10 years.

Trial registration number

NCT04166903.

Association between physical activity and risk of incident arrhythmias in 402 406 individuals: evidence from the UK Biobank cohort

Aims

Physical activity reduces cardiovascular disease burden and mortality, although its relationship with cardiac arrhythmias is less certain. The aim of this study was to assess the association between self-reported physical activity and atrial fibrillation (AF), ventricular arrhythmias and bradyarrhythmias, across the UK Biobank cohort.

Methods and results

We included 402 406 individuals (52.5% female), aged 40–69 years, with over 2.8 million person-years of follow-up who underwent self-reported physical activity assessment computed in metabolic equivalent-minutes per week (MET-min/wk) at baseline, detailed physical assessment and medical history evaluation. Arrhythmia episodes were diagnosed through hospital admissions and death reports. Incident AF risk was lower amongst physically active participants, with a more pronounced reduction amongst female participants [hazard ratio (HR) for 1500 vs. 0 MET-min/wk: 0.85, 95% confidence interval (CI) 0.74–0.98] than males (HR for 1500 vs. 0 MET-min/wk: 0.90, 95% CI 0.82–1.0). Similarly, we observed a significantly lower risk of ventricular arrhythmias amongst physically active participants (HR for 1500 MET-min/wk 0.78, 95% CI 0.64–0.96) that remained relatively stable over a broad range of physical activity levels between 0 and 2500 MET-min/wk. A lower AF risk amongst female participants who engaged in moderate levels of vigorous physical activity was observed (up to 2500 MET-min/wk). Vigorous physical activity was also associated with reduced ventricular arrhythmia risk. Total or vigorous physical activity was not associated with bradyarrhythmias.

Conclusion

The risk of AF and ventricular arrhythmias is lower amongst physically active individuals. These findings provide observational support that physical activity is associated with reduced risk of atrial and ventricular arrhythmias.

The athlete's heart is a proarrhythmic heart, and what that means for clinical decision making

Recurring questions when dealing with arrhythmias in athletes are about the cause of the arrhythmia and, more importantly, about the eligibility of the athlete to continue sports activities. In essence, the relation between sports and arrhythmias can be understood along three lines: sports as arrhythmia trigger on top of an underlying problem, sports as arrhythmic substrate promotor, or sports as substrate inducer. Often, there is no sharp divider line between these entities. The athlete's heart, a heart that adapts so magically to cope with the demands of exercise, harbours many structural and functional changes that by themselves predispose to arrhythmia development, at the atrial, nodal and ventricular levels. In essence, the athlete's heart is a proarrhythmic heart. This review describes the changes in the athlete's heart that are related to arrhythmic expression and focuses on what this concept means for clinical decision making. The concept of the athlete's heart as a proarrhythmic heart creates a framework for evaluation and counselling of athletes, yet also highlights the difficulty in predicting the magnitude of associated risk. The management uncertainties are discussed for specific conditions like extreme bradycardic remodelling, atrioventricular nodal reentrant tachycardia, atrial fibrillation and flutter, and ventricular arrhythmias.

Inherited primary arrhythmia disorders: cardiac channelopathies and sports activity

Sudden cardiac death (SCD) in an apparently healthy individual is a tragedy. It is important to identify the cause of death and to prevent SCD in potentially at-risk family members. Inherited primary arrhythmia disorders are associated with exercise-related SCD. Despite the well-known benefits of exercise, exercise restriction has been a historical mainstay of therapy for these conditions. However, since familiarity with inherited arrhythmia conditions has increased and patients are often children and young adults, it is necessary to reassess the treatment guidelines regarding exercise constraints. The aim of this review is to analyze the risk of exercise-induced SCD in patients with inherited cardiac conditions and explore the challenges faced when advising patients about exercise limitations. We searched for publications on cardiac channelopathies in PubMed with the following medical subject headings (MeSH): "long QT syndrome"; "short QT syndrome"; "Brugada syndrome"; and "catecholaminergic polymorphic ventricular tachycardia". The abstracts of these articles were scanned, and articles of relevance, along with pertinent references, were read in full. The analysis was restricted to reports published in English. The findings of this analysis suggest that exercise with low-to-moderate cardiovascular demand may be possible under regular clinical follow-up in inherited primary arrhythmia disorders. Recent data show that patients with inherited primary arrhythmia disorders are at low risk for events once a comprehensive treatment program has been established. Recreational activity is likely safe for these individuals, with personalized management based on individual patient preferences and priorities.

Is There a Role for Genes in Exercise-Induced Atrial Cardiomyopathy?

In endurance athletes, prolonged high intensity exercise participation can have deleterious effects on the myocardium with subsequent structural and electrical remodelling. In a subset of athletes, there is a predilection for atrial involvement and the risk of atrial fibrillation (AF) is increased. The mechanisms underpinning exercise-induced atrial cardiomyopathy have yet to be fully elucidated and the contribution of an individual's genetic makeup is unknown. Some athletes may have rare genetic variants that are sufficient to cause AF irrespective of exercise exposure. In AF-causing variant carriers, the additional haemodynamic stress of exercise on atrial structure and function might accelerate or increase the severity of disease. Variants in genes that lack known links to AF may indirectly promote an arrhythmogenic substrate by affecting threshold levels for exercise-induced myocardial damage and remodelling responses, or by effects on AF-associated co-morbidities, sinus node function, and autonomic nervous system tone. Given the exquisite stress-sensitivity of the atria, mechanosensitive ion channels could plausibly have a key role in mediating exercise effects on atrial structure and function. Knowing an athlete's profile of genetic variants may be useful for AF risk stratification and have implications for clinical management. Pre-participation genetic testing may influence sports choices and facilitate AF prevention.

Exercise-Induced Atrial Remodeling: The Forgotten Chamber

Cardiac changes in athletes involve the left ventricle and atrium. Mild left atrial enlargement is common among competitive athletes, possibly a physiologic adaptation to exercise conditioning. The prevalence of this remodeling and the association with supraventricular arrhythmias has not been systematically addressed. Echocardiography screens for patients with disease involving the left atrium. New techniques like speckle tracking can recognize early atrial dysfunction and assess left atrial myocardial function in patients with either physiologic or pathologic left ventricular hypertrophy. This article reviews echocardiographic techniques in delineating the athlete's morphology and functional properties of the left atrium.

Atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac rhythm disorder, and increases in prevalence with increasing age and the number of cardiovascular comorbidities. AF is characterized by a rapid and irregular heartbeat that can be asymptomatic or lead to symptoms such as palpitations, dyspnoea and dizziness. The condition can also be associated with serious complications, including an increased risk of stroke. Important recent developments in the clinical epidemiology and management of AF have informed our approach to this arrhythmia. This Primer provides a comprehensive overview of AF, including its epidemiology, mechanisms and pathophysiology, diagnosis, screening, prevention and management. Management strategies, including stroke prevention, rate control and rhythm control, are considered. We also address quality of life issues and provide an outlook on future developments and ongoing clinical trials in managing this common arrhythmia.

The Epidemiology of Atrial Fibrillation and Stroke

The burden of stroke is increasing due to aging population and unhealthy lifestyle habits. The considerable rise in atrial fibrillation (AF) is due to greater diffusion of risk factors and screening programs. The link between AF and ischemic stroke is strong. The subtype most commonly associated with AF is cardioembolic stroke, which is particularly severe and shows the highest rates of mortality and permanent disability. A trend toward a higher prevalence of cardioembolic stroke in high-income countries is probably due to the greater diffusion of AF and the control of atherosclerotic of risk factors.

[Atrial fibrillation and physical activity. An overview]

A training-induced increase in vagal tone, left atrial enlargement and high atrial volume load due to exercise can theoretically favor induction and continuation of atrial fibrillation (AF) in (endurance) athletes. However, there is currently no evidence for a higher occurrence of AF in young endurance athletes in comparison to an age-matched normal population. The correlate of long-term endurance training results in proarrhythmogenic atrial remodeling in a rat model. The results of some studies also suggest that there may be atrial remodeling in humans, which might be an explanation for the comparatively higher incidence of AF in veteran athletes, whereby the relative risk might have been overestimated due to methodological problems, e.g. due to insufficient consideration of "new" AF risk factors. To date, there are no indications for an increased risk of AF due to normal physical activity: on the contrary, moderate physical activity seems to decrease the risk for AF. For an individual evaluation of sports participation of patients with AF, the overall cardiac situation, atrioventricular conduction during exercise, a possible oral anticoagulation as well as the sport and training intensity practiced are important. Well-adapted training for patients with AF has to be considered as safe and effective in terms of the overall positive effects of physical activity in patients with cardiovascular problems, for example due to a positive influence on cardiovascular risk factors.

Relationship between Inflammatory Cytokines and Indices of Cardiac Dysfunction following Intense Endurance Exercise

Objectives

Pro-inflammatory cytokines have been noted to increase following exercise but their relationship to exercise-induced cardiac dysfunction has not previously been investigated. We sought to evaluate whether exercise-induced cardiac dysfunction was associated with increases in cytokines, particularly the pro-inflammatory cytokines IL-1β, IL-12p70 and TNFα, which have been most implicated in cardiac pathology.

Methods

40 well-trained endurance athletes underwent evaluation prior to and immediately following one of four endurance sporting events ranging from 3 to 11 hours duration. Cytokines (IL-1β, IL-6, IL-8, IL-10, IL-12p70 and TNFα) were analyzed by flow cytometry from serum samples collected within 50 minutes of race completion. Cardiac troponin (cTnI) and B-type natriuretic peptide were combined with an echocardiographic assessment of cardiac function, and a composite of cTnI > 0.04 μg/L, BNP increase > 10 ng/L and a decrease in right ventricular ejection (RVEF) > 10% were prospectively defined as evidence of myocardial dysfunction.

Results

Relative to baseline, IL-6 IL-8 and IL-10 increased 8.5-, 2.9-, and 7.1-fold, respectively, P<0.0001. Thirty-one (78%), 19 (48%) and 18 (45%) of the athletes met the pre-specified criteria for significant cTnI, BNP and RVEF changes, respectively. TNFα, IL-12p70 were univariate predictors of ΔRVEF and ΔBNP whilst none of the anti-inflammatory cytokines were significantly associated with these measures. Ten athletes (25%, all athletes competing in the endurance event of longest duration) met criteria for exercise-induced myocardial dysfunction. In these 10 athletes with myocardial dysfunction, as compared to those without, there was significantly greater post-race expression of the pro-inflammatory cytokines IL-12p70 (8.1±3.8pg/ml vs. 2.5±2.6pg/ml, P<0.0001) and TNFα (6.5±3.1pg/ml vs. 2.0±2.5pg/ml, P<0.0001).

Conclusion

Cardiac dysfunction following intense endurance exercise was associated with increased expression of pro-inflammatory cytokines. This does not prove a causal relationship but provides rationale for further investigations into whether inflammation mediates exercise-induced myocardial dysfunction.

Physiologic and pathophysiologic changes in the right heart in highly trained athletes

Exercise causes changes in the heart in response to the hemodynamic demands of increased systemic and pulmonary requirements during exercise. Understanding these adaptations is of great importance, since they may overlap with those caused by pathological conditions. Initial descriptions of athlete's heart focused mainly on chronic adaptation of the left heart to training. In recent years, the substantial structural and functional adaptations of the right heart have been documented, highlighting the complex interplay with left heart. Moreover, there is evolving evidence of acute and chronic cardiac damage, mainly involving the right heart, which may predispose subjects to atrial and ventricular arrhythmias, configuring an exercise-induced cardiomyopathy. The aim of this article is to review the current knowledge on the physiologic and pathophysiologic changes in the right heart in highly trained athletes.

Exercise and cardiovascular risk in patients with hypertension

Evidence for the benefits of regular exercise is irrefutable and increasing physical activity levels should be a major goal at all levels of health care. People with hypertension are less physically active than those without hypertension and there is strong evidence supporting the blood pressure-lowering ability of regular exercise, especially in hypertensive individuals. This narrative review discusses evidence relating to exercise and cardiovascular (CV) risk in people with hypertension. Comparisons between aerobic, dynamic resistance, and static resistance exercise have been made along with the merit of different exercise volumes. High-intensity interval training and isometric resistance training appear to have strong CV protective effects, but with limited data in hypertensive people, more work is needed in this area. Screening recommendations, exercise prescriptions, and special considerations are provided as a guide to decrease CV risk among hypertensive people who exercise or wish to begin. It is recommended that hypertensive individuals should aim to perform moderate intensity aerobic exercise activity for at least 30 minutes on most (preferably all) days of the week in addition to resistance exercises on 2-3 days/week. Professionals with expertise in exercise prescription may provide additional benefit to patients with high CV risk or in whom more intense exercise training is planned. Despite lay and media perceptions, CV events associated with exercise are rare and the benefits of regular exercise far outweigh the risks. In summary, current evidence supports the assertion of exercise being a cornerstone therapy in reducing CV risk and in the prevention, treatment, and control of hypertension.

Right Ventricular Changes in Highly Trained Athletes: Between Physiology and Pathophysiology

Several studies have described the adaptive remodeling of the heart during exercise. In some more practiced endurance athletes, there is a disproportionate load on the right ventricle (RV), at least during exercise, and this might be the basis for a chronic pro-arrhythmic RV remodeling. Especially, in these kinds of athletes the recovery after detraining might be incomplete, in particular for RV changes. The observation of acute myocardial injury based on transient elevation of biomarkers and chronic myocardial scar, not completely reversible changes of the RV and an increased prevalence of some arrhythmias support the existence of an “exercise-induced cardiomyopathy.” The aim of this paper is to review current knowledge about changes in the right heart in highly trained athletes and how these change influence cardiac function.

Effect of years of endurance exercise on risk of atrial fibrillation and atrial flutter

Emerging evidence suggests that endurance exercise increases the risk for atrial fibrillation (AF) in men, but few studies have investigated the dose-response relation between exercise and risk for atrial arrhythmias. Both exposure to exercise and reference points vary among studies, and previous studies have not differentiated between AF and atrial flutter. The aim of this study was to assess the risk for atrial arrhythmias by cumulative years of regular endurance exercise in men. To cover the range from physical inactivity to long-term endurance exercise, the study sample in this retrospective cohort study was based on 2 distinct cohorts: male participants in a long-distance cross-country ski race and men from the general population, in total 3,545 men aged ≥ 53 years. Arrhythmia diagnoses were validated by electrocardiograms during review of medical records. Regular endurance exercise was self-reported by questionnaire. A broad range of confounding factors was available for adjustment. The adjusted odds ratios per 10 years of regular endurance exercise were 1.16 (95% confidence interval 1.06 to 1.29) for AF and 1.42 (95% confidence interval 1.20 to 1.69) for atrial flutter. In stratified analyses, the associations were significant in cross-country skiers and in men from the general population. In conclusion, cumulative years of regular endurance exercise were associated with a gradually increased risk for AF and atrial flutter.

Multiple sclerosis clinical course and cardiovascular disease risk - Swedish cohort study

BACKGROUND AND PURPOSE

Cardiovascular disease (CVD) risk amongst multiple sclerosis (MS) patients appears raised, but few studies have examined CVD risk amongst an unselected MS patient group. MS course may be relevant for CVD risk. Our aim was to assess CVD risk and variation by course in MS patients.

METHODS

The Multiple Sclerosis Register identified 7667 patients who received an MS diagnosis between 1964 and 2005. They were matched by age, period, region and sex with 76 045 members of the general population without MS using Swedish registers. Poisson regression compared the two cohorts to estimate the relative risk for CVD, overall, as well as grouped and individual CVD diagnoses.

RESULTS

MS patients had an increased adjusted relative risk (with 95% confidence intervals; number of MS cohort events) for CVD of 1.31 (1.22-1.41; n = 847), with some variation by course: relapsing-remitting 1.38 (1.17-1.62; n = 168); secondary progressive 1.30 (1.18-1.53; n = 405) and primary progressive 1.15 (0.93-1.41; n = 108). The association for the relapsing-remitting course was not significant after excluding the first year of follow-up. Overall incidence rates per 1000 person-years for CVD are 11.8 (11.06-12.66) for the MS cohort and 8.8 (8.60-9.05) for the non-MS cohort. The most pronounced association was for deep vein thrombosis: relapsing-remitting 2.16 (1.21-3.87; n = 14), secondary progressive 3.41 (2.45-4.75; n = 52) and primary progressive 3.57 (1.95-6.56; n = 15). MS was associated with ischaemic stroke but largely during the first year of follow-up. MS was associated with a decreased relative risk for angina pectoris and atrial fibrillation.

CONCLUSIONS

There is a significantly increased relative risk for CVD in MS, particularly for venous thromboembolic disorders in progressive MS, suggesting immobility as a possible factor. An increased frequency of ischaemic stroke in MS is most probably due to surveillance bias resulting from diagnostic investigations for MS. There is no increased relative risk for ischaemic heart disease in MS and atrial fibrillation appears to be less common than amongst the general population.

Physical exercise and health

Regular physical exercise is an established recommendation for preventing and treating the main modifiable cardiovascular risk factors, such as diabetes mellitus, hypertension, and dyslipidemia. Performing physical activity of moderate intensity for a minimum of 30 min 5 days a week or of high intensity for a minimum of 20 min 3 days a week improves functional capacity and is associated with reductions in the incidence of cardiovascular disease and mortality. Physical exercise induces physiological cardiovascular adaptations that improve physical performance, and only in extreme cases can these adaptations lead to an increased risk of physical exercise-associated complications. The incidence of sudden death or serious complications during physical exercise is very low and is concentrated in people with heart diseases or with pathological cardiac adaptation to exercise. Most of these cases can be detected by cardiology units or well-trained professionals.

Exercise and competitive sports in patients with an implantable cardioverter-defibrillator

Implantable cardioverter-defibrillators (ICDs) prevent sudden arrhythmic death in patients with different arrhythmogenic cardiac diseases. Because intense physical activity may trigger ventricular arrhythmias and may favour inappropriate shock delivery that impacts quality of life, current international recommendations only give clearance for moderate leisure-time physical activity to patients with an ICD. Hence, athletes are deemed non-eligible to compete with their ICD. The rationale for the current restriction from competitive sports is discussed in this review, as well as new insights that may alter these recommendations for certain sports participants in the foreseeable future. This review provides guidance for the choice of a durable lead and device system, careful programming tailored to the characteristics of the patient's physiological and pathological heart rhythms, instalment of preventive bradycardic medication, and guided rehabilitation with psychological counselling, allowing a maximum of benefit and a minimum of harm for physically active ICD patients.

[Medicinal treatment of atrial fibrillation in special situations]

The treatment of atrial fibrillation has to take into account the underlying cardiac and extracardiac diseases. A successful treatment of the underlying disease will only be sufficient treatment of atrial fibrillation in very rare situations. Therefore, this review focuses on the consequences of underlying heart disease, the hemodynamics and concomitant clinical situations on the treatment of atrial fibrillation.