Gender differences of atrial and ventricular remodeling and autonomic tone in nonelite athletes

Determinants of supraventricular extra beats in elite athletes practicing different sporting disciplines

BACKGROUND

Supraventricular extra beats (SVEB) are frequently observed in athletes but data on significance, prognostic role and correlation with cardiac remodeling are contrasting. It is uncertain whether SVEB may indicate the development of more complex arrhythmias and the need for closer monitoring is undetermined. The aim was to assess the prevalence and clinical significance of BESV in Olympic athletes of different sporting disciplines, evaluating potential correlations with cardiac remodeling and clinical features.

METHODS

We enrolled athletes who participated at 2012-2022 Olympic Games, submitted to physical examination, blood tests, echocardiography and exercise tests, categorized into power, skills, endurance and mixed disciplines.

RESULTS

We studied 1492 elite athletes: 56% male individuals, mean age 25.8 ± 5.1 years; 29.5% practiced power, 12.3% skills, 21% endurance and 37.2% mixed disciplines. At exercise-stress tests, 6.2% had SVEB, mostly single beats. SVEB were not influenced by anthropometrics or blood test results. They were more common in male individuals (77.4 vs. 54.6%, P < 0.0001) and older athletes (27.1 ± 5.7 vs. 25.7 ± 5.1, P = 0.01). In male athletes with SVEB, higher left atrial volumes were observed (24.2 ± 7.3 vs. 22.2 ± 7.1 ml/m2, P = 0.03). No differences were found in terms of sporting discipline: despite larger left atrial dimensions in aerobic disciplines, SVEB rates were similar in different sporting disciplines (6.1% endurance, 6.3% mixed, 5.2% power and 8.7% skills; P = 0.435).

CONCLUSION

SVEB were more common in older, male athletes and associated with higher left atrial volume (especially in male individuals) regardless of sport practiced. Athletes with greater left atrial volume and SVEB are supposed to have higher risk, in middle age, of developing more complex arrhythmias.

Leisure-time physical activity and the incidence of atrial fibrillation in senior adults: a prospective cohort study

OBJECTIVE

Whether physical activity could reduce the risk of atrial fibrillation (AF) remains unclear. This study was to investigate the relationship of leisure-time physical activity (LTPA) with AF incidence among Chinese older adults.

METHODS

A total of 3253 participants aged ≥60 years from the Guangzhou Heart Study were successfully followed between March 2018 and September 2019. LTPA was assessed using a modified Global Physical Activity Questionnaire. AF was ascertained by 12-lead electrocardiograms, 24-hour single-lead Holter and clinical examination. The Cox proportional hazards model was used to the estimate hazard ratio (HR) and 95% confidence interval (CI) after adjustment for confounders, and the population-attributable fraction (PAF) was estimated.

RESULTS

A total of 76 (2.34%) new-onset cases of AF were identified during a median of 31.13 months of follow-up. After adjustment for confounders, subjects who had LTPA at least 10.0 metabolic equivalent (MET)-hours/week had a 55% lower risk of developing AF (HR: 0.45, 95%CI: 0.25-0.81), and at least 20 MET-hours/week reduced the risk by 45% (HR: 0.55, 95%CI: 0.34-0.92). At least 11% (PAF: 11%, 95%CI: 0%-20%) or 14% (PAF: 14%, 95%CI: 0%-26%) of AF cases could be avoided, respectively, if the subjects do LTPA at least 10 MET-hours/week or 20 MET-hours/week. A significant exposure-response trend was also observed between LTPA and AF risk (Plinear-trend = 0.002). For a specific LTPA, doing housework was associated with a 43% reduced risk, while engaging in ball games was associated with an increased risk.

CONCLUSION

This prospective cohort study indicated that a higher LTPA volume was associated with a lower AF risk in Chinese older adults.

Leisure-time and occupational physical activity and risk of cardiovascular disease incidence: a systematic-review and dose-response meta-analysis of prospective cohort studies

BACKGROUND AND OBJECTIVE

Physical activity has benefits for the cardiovascular system, however, what levels and types of activity provide optimal cardiovascular health is unclear. We aimed to determine the level of physical activity that has the most benefits against cardiovascular diseases (CVD).

METHODS

PubMed, Scopus, and Web of Science were searched for prospective cohort studies on leisure-time (LTPA) or occupational physical activity (OPA) as the exposure and major types of CVD (total CVD, coronary heart disease [CHD], stroke, and atrial fibrillation [AF]) incidence as the outcome. Risk of bias of studies was evaluated using the ROBINS-I tool. Summary hazard ratios (HR) were calculated using random-effects pairwise model.

RESULTS

A total of 103 studies were included in the analysis. The highest versus the lowest LTPA was associated with a lower risk of overall CVD (HR = 0.81; 95% CI: 0.77-0.86), CHD (HR = 0.83; 0.79-0.88), and stroke (HR = 0.83; 0.79-0.88), but not AF (HR = 0.98; 0.92-1.05). Linear dose-response analyses showed a 10%, 12%, 9%, and 8% risk reduction in CVD, CHD, stroke, and AF incidence, respectively, for every 20 MET-hours/week increase in LTPA. In nonlinear dose-response analyses, there were inverse associations up to 20 MET-hours/week with 19% and 20% reduction in CVD and CHD risk, and up to 25 MET-hours/week with 22% reduction in stroke, with no further risk reduction at higher LTPA levels. For AF, there was a U-shaped nonlinear association with the maximum 8% risk reduction at 10 MET-hours/week of LTPA. Higher levels of OPA were not associated with risk of CVD, CHD, stroke, or AF.

CONCLUSIONS

Overall, results showed an inverse dose-response relationship between LTPA and risk of CVD, CHD, stroke, and AF. Running was the most beneficial LTPA but the risk was similar among various LTPA intensities. OPA showed no benefits in total or any type of CVD.

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.

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.

[Analysis of sudden cardiac death in competitive athletes, possibilities for reducing cases]

INTRODUCTION

Sudden cardiac death in athletes is rare (0.5 to 1 per 100 000 athlete years), but sudden cardiac death in known athletes causes general shock.

OBJECTIVE

Our research aim was to collect and study as many sudden cardiac death cases as possible, judge the role of stress and look for ways to reduce fatal tragedies.

METHOD

From registers and newspaper articles found on the Internet, we collected 360 (including 14 women) athletes' sudden cardiac death cases where the sport, age and place of death (during training/competition/after) could be determined. From these, a single database has been prepared in order of the year of death. The cases were grouped and analyzed by sports. Based on our results and literature data, we made recommendations to reduce fatalities.

RESULTS AND CONCLUSION

There were more sudden cardiac deaths in competitions than in trainings (239 vs. 99), but tragedies also happened during warm-ups and chess without physical exertion, furthermore, there was no sudden cardiac death in the stakeless training of marathon/half marathon/triathlon athletes; all these prove the role of stress, so we recommend a psychological conversation before a high-stakes race. There were also a lot of sudden cardiac deaths (79/360) during team sports trainings, so we recommend reanimation readiness there as well. After training/competition, sudden cardiac death happened mainly in sports requiring high static effort, where post-competition monitoring is also recommended. Those who died in training were younger than those who died during the race (p<0.01), so young people should be monitored more closely for medical and (under)fitness. Marathon runners and triathletes were older than team athletes (p<0.005) and only died in competition, so for them a basic examination and an ECG within 1 month before competition are recommended. Conclusions drawn from literature data: sports medicine examination should be standardized and documented in an accessible way; since resuscitation started earlier and professionally is more effective, all competitors should receive reanimation training. Orv Hetil. 2023; 164(29): 1155-1163.

A New Approach for Evaluation of Cardiovascular Fitness and Cardiac Responses to Maximal Exercise Test in Master Runners: A Cross-Sectional Study

The aim of this study was to analyze the cardiac autonomic function at rest, at maximum exercise, and in recovery after exercise and to determine sex-specific and age-specific values for resting heart rate (RHR), hear rate (HR)-peak, HR recovery (HRR), and HR variability at rest in master runners. Fifty endurance runners (21 women) participated in this study (43.28 ± 5.25 years). The subjects came from different athletic clubs in Andalusia (Spain), and the testing protocol was performed in-season. A 3-km running test was performed and the cardiovascular response was monitored. Regarding sex, no significant differences were found regarding cardiovascular autonomic function at rest, during exercise, and following maximal exercise, only at rest, the standard deviation of all R-R intervals and low frequency values displayed significantly (p < 0.05) lower scores in women. 46% of athletes showed an RHR < 60 bpm. Additionally, HR-peak showed a significant correlation with age (r = −0.369; p = 0.009) and HRR5min (r = 0.476, p = 0.001). Also, endurance performance was inversely associated with obesity traits and cardiometabolic risk factors. In summary, age, sex, fitness, or anthropometrics characteristics did not show a relevant influence on cardiovascular autonomic modulation in master runners. However, the 3-km performance displayed a significant negative association with several factors of cardiometabolic risk.

Electrical and Structural Adaption of Athlete’s Heart and the Impact on Training and Recovery Management in Professional Basketball Players: A Retrospective Observational Study

Introduction

We analyzed data of 27 professional basketball players to prove cardiac remodeling referring echocardiographic parameters, cardiopulmonary exercise testing (CPET), and 12-lead electrocardiogram (ECG) analyses. The aim of our study was to present different characteristics in the athletes, on the one hand signs of a high vagal tone in the 12-lead ECG as criteria of early repolarization (ER), furthermore echocardiographic remodeling parameters and finally the performance in CPET. Therefore, we divided the cohort into a group with signs of ER pattern in the 12-lead ECG and without these criteria and presented the differences in detail.

Materials and Methods

This was a single-center, retrospective study performed in 27 professional basketball players (age: 26.5 ± 7.5 years, male: 27, height: 197.2 ± 12 cm, weight: 100 ± 17 kg, BMI: 25.7 ± 3.4 kg/m2). All participants underwent a sports medicine checkup, ECG analysis, transthoracic echocardiographic examination, and a CPET on a cycle ergometer between 2015 and 2019 during their pre-season preparation time. All individuals were healthy people without cardiological advance anamnesis. After assessment, two groups were built based on electrocardiographic criteria of ER pattern and a group without these criteria and compared against each other for parameters of echocardiographic assessment, CPET, and 12-lead ECG analysis. Data were analyzed with Minitab statistic program (Minitab Inc., State College, PA, United States) and Graph Pad Prism 8.2.1 (279; Graph Pad Software, San Diego, CA, United States) using ANOVA testing with post-hoc testing and unpaired t-testing (p ≤ 0.05).

Retrospectively additional information was collected referring to the management of training sessions, recovery time, and nutrition by interviewing the athletic training staff in order to understand the principles for individual athlete’s training management and physiological and cardiopulmonary interactions.

Results

Comparing professional basketball players with ER pattern to those with no ER pattern, significant differences were found for CPET, echocardiographic, and ECG analysis (p &lt; 0.05). Absolute and relativized peak oxygen uptake (VO2 peak; ER 4120 ± 750 ml/min (39 ± 5.4 ml/kg/min) vs. non-ER 3556 ± 393 ml/min (37.2 ± 5.3 ml/kg/min), p = 0.018) and maximum workload during CPET (ER 310 ± 51.5 Watt (2.94 ± 0.35 W/kg) vs. non-ER 271 ± 32 Watt (2.85 ± 0.49 W/kg), p = 0.026) was higher in athletes with an ER pattern. Furthermore, ER pattern athletes showed a higher enddiastolic left ventricular diameter (LVedd; ER 58.3 ± 7.9 mm vs. non-ER 53.6 ± 3.6 mm, p = 0.048) and a significantly enlarged left atrial (LA) endsystolic diameter (ER 23.33 ± 2.71 mm vs. non-ER 20.47 ± 2.29 mm, p = 0.006) as well as a significantly enlarged right atrial (RA) endsystolic diameter (ER 23.42 ± 2.15 mm vs. non-ER 20.93 ± 3.28 mm, p = 0.033). Significant differences between the two compared groups could be revealed for left ventricular mass Index (LVMI gr/m2; LVMI ER 113 gr/m2 ± 17.5 vs. LVMI non-ER 91.3 gr/m2 ± 15.1, p = 0.002), but no significant differences for the relative wall thickness were found (RWT; RWT ER 0.49 ± 0.11 vs. RWT non-ER 0.38 ± 0.06, p = 0.614).

Conclusion

Professional basketball players with criteria of ER pattern showed different results in CPET and cardiac remodeling as athletes with no ER pattern. These findings should encourage the athletic training staff to emphasize the quality of an individual training schedule for each athlete based on the cardiopulmonary pre-season sport medicine checkup. Nevertheless, echocardiographic findings, ER pattern, and performance in CPET have to be interpreted referring the sport-specific and athlete’s ethnical background.

Conditioning Program Prescribed from the External Training Load Corresponding to the Lactate Threshold Improved Cardiac Function in Healthy Dogs

This research focuses on the adjustments in systolic and diastolic functions that are not fully understood in dogs submitted to athletic training. Beagle dogs carried out an endurance training program (ETP) prescribed from the external training load, corresponding to 70-80% of the lactate threshold (VLT) velocity. Eighteen dogs were randomly assigned to two groups: control (C, n = 8), active dogs that did not perform any forced exercise, and trained (T, n = 10), submitted to the ETP during eight weeks. All dogs were evaluated before and after the ETP period using two-dimensional echocardiography, M-mode, Doppler, and two-dimensional speckle tracking. A principal component analysis (PCA) of the echocardiographic variables was performed. The ETP improved the left ventricular internal dimension at the end of diastole (LVDd), the left ventricular internal dimension at the end of diastole to aorta ratio (LVDd: Ao), and the strain rate indices. PCA was able to capture the dimensionality and qualitative echocardiography changes produced by the ETP. These findings indicated that the training prescribed based on the lactate threshold improved the diastolic and systolic functions. This response may be applied to improve myocardial function, promote health, and mitigate any injuries produced during heart failure.

Subclinical Atrial Fibrillation: A Silent Threat with Uncertain Implications

Atrial fibrillation (AF) is one of the most common cardiac arrhythmias. Implantable and wearable cardiac devices have enabled the detection of asymptomatic AF episodes-termed subclinical AF (SCAF). SCAF, the prevalence of which is likely significantly underestimated, is associated with increased cardiovascular and all-cause mortality and a significant stroke risk. Recent advances in machine learning, namely artificial intelligence-enabled ECG (AI-ECG), have enabled identification of patients at higher likelihood of SCAF. Leveraging the capabilities of AI-ECG algorithms to drive screening protocols could eventually allow for earlier detection and treatment and help reduce the burden associated with AF. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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.

Sex-Specific Impacts of Exercise on Cardiovascular Remodeling

Cardiovascular diseases (CVD) remain the leading cause of death in men and women. Biological sex plays a major role in cardiovascular physiology and pathological cardiovascular remodeling. Traditionally, pathological remodeling of cardiovascular system refers to the molecular, cellular, and morphological changes that result from insults, such as myocardial infarction or hypertension. Regular exercise training is known to induce physiological cardiovascular remodeling and beneficial functional adaptation of the cardiovascular apparatus. However, impact of exercise-induced cardiovascular remodeling and functional adaptation varies between males and females. This review aims to compare and contrast sex-specific manifestations of exercise-induced cardiovascular remodeling and functional adaptation. Specifically, we review (1) sex disparities in cardiovascular function, (2) influence of biological sex on exercise-induced cardiovascular remodeling and functional adaptation, and (3) sex-specific impacts of various types, intensities, and durations of exercise training on cardiovascular apparatus. The review highlights both animal and human studies in order to give an all-encompassing view of the exercise-induced sex differences in cardiovascular system and addresses the gaps in knowledge in the field.

Electrocardiographic Changes in Male and Female Amateur Marathon Runners: A Comparison Study

Physical training is gaining popularity among amateurs. Males and females exhibit different cardiac adaptation to exercise. The aim of the study was to compare the incidence of electrocardiographic abnormalities before and after the marathon between sexes. 12-lead electrocardiogram was performed in 40 male (39±8 years) and 27 female (40±7 years) amateur runners: 2-3 weeks before (Stage 1) and immediately after (Stage 2) the marathon. Abnormalities in the resting (Stage 1) and exercise (Stage 2) electrocardiograms were compared between sexes. At rest left atrial enlargement was more frequent in females than males (48 vs. 20%; p<0.05). The incidence of right atrial enlargement was significantly more common at Stage 2 than 1, both in men (43 vs. 0%; p<0.001) and in women (48 vs. 4%; p=0.001). Significant increase of P-wave amplitude was found in male runners after the marathon (0.12±0.05 vs. 0.21±0.09 mV; p<0.001 Stage 1 vs. 2), but was absent in females. QTc prolongation was observed in both sexes, however to a higher degree in males (p<0.05 for the interaction stage and sex). Although both male and female amateur marathon runners exhibit abnormalities in resting and exercise electrocardiograms, men present more exercise-induced electrocardiographic changes, which might indicate a higher propensity for post-marathon arrhythmias. Electrocardiographic screening in amateurs should be considered.

The Female Athlete's Heart: Overview and Management of Cardiovascular Diseases

The number of female athletes taking part in elite and amateur sport is ever increasing. In contrast with male athletes, few studies have focused on cardiovascular adaptations to exercise in women, the effects of lifelong exercise on heart muscle and electrical tissue, the risk of exerciserelated sudden cardiac death and the management of cardiovascular disease. Women have a lower prevalence of large QRS complexes, repolarisation changes including inferior and lateral T-wave inversion, and cardiac dimensions exceeding predicted limits compared with men. The risk of exercise-related sudden cardiac death is significantly lower in women than men. Also, women who have engaged in lifelong exercise do not have a higher prevalence of AF, coronary artery calcification or myocardial fibrosis than their sedentary counterparts. Apart from providing an overview of the existing literature relating to cardiac adaptations, this review explores possible reasons for the sex differences and focuses on the management of cardiovascular disorders that affect female athletes.

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

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

Systematic review registration: PROSPERO 2020: CRD42020172814

Female Athlete's Heart: Sex Effects on Electrical and Structural Remodeling

BACKGROUND

Most of our knowledge on training-induced cardiac remodeling is derived from men, with the paucity of data from women representing an important gap in knowledge. The aim of the study was to define the electrocardiographic and morphological features of female athlete's heart, with special attention to differences related to sex and sport.

METHODS

Seven hundred twenty Olympic athletes (360 females and 360 age- and sport-matched males, mean age: 23±5 years) were evaluated by clinical, resting, and exercise electrocardiography and echocardiography.

RESULTS

Anterior T-wave inversion was more common in females than males (P<0.05). Left ventricular (LV) wall thickness and LV mass were greater in men (P<0.001). Females had smaller absolute but greater indexed LV and right ventricular (RV) dimensions as compared to males. Most women had normal LV geometry (80.8%). A progressive increase in LV/RV dimensions was observed in women from those engaged in skill, power, to mixed and endurance disciplines, with the endurance ones demonstrating the greatest degree of RV dilatation. Women had a peculiar biventricular adaptation, with higher LV/RV (1.41±0.16 versus 1.36±0.15, P<0.0001) and lower RV inflow/outflow ratio (P<0.001), as compared to men.

CONCLUSIONS

Sex significantly affects cardiac remodeling in athletes, with females presenting a different electrical and structural remodeling. Women maintain a normal LV geometry, with relative larger increase of cavity dimensions compared with men. Type of sport has a relevant impact, with endurance athletes exhibiting the greatest degree of RV and LV dimensional remodeling. The present study confirms the need for a sex-based approach for interpreting the complex features of athlete's heart in women.

Heart Rate Monitor Instead of Ablation? Atrioventricular Nodal Re-Entrant Tachycardia in a Leisure-Time Triathlete: 6-Year Follow-Up

This study describes a triathlete with effort-provoked atrioventricular nodal re-entrant tachycardia (AVNRT), diagnosed six years ago, who ineffectively controlled his training load via heart-rate monitors (HRM) to avoid tachyarrhythmia. Of the 1800 workouts recorded for 6 years on HRMs, we found 45 tachyarrhythmias, which forced the athlete to stop exercising. In three of them, AVNRT was simultaneously confirmed by a Holter electrocardiogram (ECG). Tachyarrhythmias occurred in different phases (after the 2^nd-131^st minutes, median: 29^th minute) and frequencies (3-8, average: 6.5 times/year), characterized by different heart rates (HR) (150-227 beats per minute (bpm), median: 187 bpm) and duration (10-186, median: 40 s). Tachyarrhythmia appeared both unexpectedly in the initial stages of training as well as quite predictably during prolonged submaximal exercise-but without rigid rules. Tachyarrhythmias during cycling were more intensive (200 vs. 162 bpm, p = 0.0004) and occurred later (41 vs. 10 min, p = 0.0007) than those during running (only one noticed but not recorded during swimming). We noticed a tendency (p = 0.1748) towards the decreasing duration time of tachycardias (2014-2015: 60 s; 2016-2017: 50 s; 2018-later: 37 s). The amateur athlete tolerated the tachycardic episodes quite well and the ECG test and echocardiography were normal. In the studied case, the HRM was a useful diagnostic tool for detecting symptomatic arrhythmia; however, no change in the amount, phase of training, speed, or duration of exercise-stimulated tachyarrhythmia was observed.

The impact of demographic, anthropometric and athletic characteristics on left atrial size in athletes

The structural adaptations of the “athlete's heart” include left atrial (LA) enlargement. A literature search was performed based on PubMed listings up to November 2, 2019 using “athletes AND left atrium,” “athletes AND LA,” “sports AND left atrium,” “sports AND LA,” “exercise AND left atrium,” and “exercise AND LA” as the search terms. Eligible studies included those reporting the influence of demographic, anthropometric and athletic characteristics on LA size in athletes. A total of 58 studies were included in this review article. Although LA volume has been reported to be greater in males compared to females when indexed for body surface area (BSA), there was no difference between sexes. The positive association between LA size and age in athletes may reflect the increase in body size with maturation in nonadult athletes and the training age of endurance athletic activity in adult athletes. Caucasian and black athletes have been demonstrated to exhibit similar LA enlargement. The positive association of LA size with lean body mass (LBM) possibly accounts for the relationship of LA size with BSA. LA enlargement has been reported only in endurance‐trained, but not in strength‐trained athletes. LA size appears to increase with an increase in both the volume and intensity of endurance training. LA size correlates independently with the training age of endurance athletes. The athlete's characteristics that independently determine LA size include LBM, endurance training, and training age.

The Association Between Atrial Fibrillation and Endurance Physical Activity: How Much is too Much?

Atrial fibrillation (AF) is the most common arrhythmia in middle-aged athletes. Physical exercise performed in a regular basis has been shown to be beneficial for cardiovascular health. Moderate physical exercise, aside from producing a nice, peaceful and well-being sensation, has been associated with a reduced risk of AF. However, more strenuous endurance exercise, like the one experiencing marathon runners, seems to increase the risk of AF in healthy athletes without organic heart disease. On the other hand, low physical activity was found to be a risk factor for the appearance of AF. Nevertheless, the relationship of exercise to AF is complex, influenced by the intensity and the duration of the physical activity, and seems to have a U-shaped relationship with the greatest levels of physical activity possibly increasing AF incidence. There is cumulative data associating moderate physical activity to reduced AF incidence, hence physicians should recommend moderate exercise training to patients with AF. This may not only reduce AF risk, but would also contribute to an overall cardiovascular benefit. However, since there is also important data suggesting significant increased incidence of AF in elite athletes with long-term endurance physical activity, it may be a serious concern to go to the extreme. In most things in life it is much better and wiser to be well balanced, always in equilibrium.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

The Female Athlete's Heart: Facts and Fallacies

Purpose of the review

For many years, competitive sport has been dominated by men. Recent times have witnessed a significant increase in women participating in elite sports. As most studies investigated male athletes, with few reports on female counterparts, it is crucial to have a better understanding on physiological cardiac adaptation to exercise in female athletes, to distinguish normal phenotypes from potentially fatal cardiac diseases. This review reports on cardiac adaptation to exercise in females.

Recent findings

Recent studies show that electrical, structural, and functional cardiac changes due to physiological adaptation to exercise differ in male and female athletes. Women tend to exhibit eccentric hypertrophy, and while concentric hypertrophy or concentric remodeling may be a normal finding in male athletes, it should be evaluated carefully in female athletes as it may be a sign of pathology. Although few studies on veteran female athletes are available, women seem to be affected by atrial fibrillation, coronary atherosclerosis, and myocardial fibrosis less than male counterparts.

Summary

Males and females exhibit many biological, anatomical, and hormonal differences, and cardiac adaptation to exercise is no exception. The increasing participation of women in sports should stimulate the scientific community to develop large, longitudinal studies aimed at a better understanding of cardiac adaptation to exercise in female athletes.

Atrial Fibrillation (AF) in Endurance Athletes: a Complicated Affair

PURPOSE OF REVIEW

A complex relationship exists between exercise and atrial fibrillation (AF). Moderate exercise reduces AF risk whereas intense strenuous exercise has been shown to increase AF burden. It remains unclear at which point exercise may become detrimental. Overall, endurance athletes remain at lower cardiovascular risk and experience fewer strokes. The questions that arise therefore are whether AF is an acceptable byproduct of strenuous exercise, whether athletes who experience AF should be told to reduce exercise volume and how should they be managed. This review aims to critically review the literature and advise on how best to manage athletes with AF.

RECENT FINDINGS

Emerging evidence suggests that female athletes may exhibit lower risk of AF, but data is limited in female endurance athletes. AF is more prevalent in endurance athletes, particularly men and those who competed at a young age. Data is lacking in females and ethnic minorities. Current evidence suggests that treatment options for AF in athletes are similar to those used in the general population; however, medical therapy may be poorly tolerated. Catheter ablation is effective and can allow return to full competition.

The effects of gender on electrical therapies for the heart: physiology, epidemiology, and access to therapies

The difference between men and women is clear even just by looking at an electrocardiogram: females present higher resting heart rate, a shorter QRS complex length and greater corrected QT interval. The development of these differences from pubertal age onward suggests that sexual hormones play a key role, although their effect is far from being completely understood. Different incidences between sexes have been reported for many arrhythmias, both ventricular and supraventricular, and also for sudden cardiac death. Moreover, arrhythmias are an important issue during pregnancy, both for diagnosis and treatment. Interestingly, cardiovascular structural and electrophysiological remodelling promoted by exercise training enhances this 'gender effect'. Despite all these relevant issues, we lack gender specific recommendations in the current guidelines for electrical therapies for heart rhythm disorders and heart failure. Even more, we continue to see that fewer women are included in clinical trials and are less referred than men for these treatments.

The association between physical activity and atrial fibrillation applying the Heaviside function in survival analysis: the Multi-Ethnic Study of Atherosclerosis

OBJECTIVES

Although the effect of physical activity (PA) on the incidence of atrial fibrillation (AF) has been studied, contradictory results have been reported. Such discrepancies may reflect the different effects of various types of PA upon AF, as well as gender interactions. Therefore, we aimed to evaluate the associations of PA types (total, moderate/vigorous, and intentional), as well as walking pace, with AF risk in men and women.

METHODS

Using the Multi-Ethnic Study of Atherosclerosis Typical Week Physical Activity Survey, 3 PA measures and walking pace were calculated among 6,487 men and women aged 45-84 years. The incidence of AF over approximately 11 years of follow-up was ascertained. The association of each PA measure and walking pace with AF incidence was estimated using multivariable Cox proportional hazard models. An extended Cox model with Heaviside functions (hv) of time was used to estimate the effects of time-varying covariates.

RESULTS

During 11 years of follow-up (49,557 person-years), 242 new AF cases occurred. The incidence rate of AF was 48.83 per 10,000 person-years. The proportional hazard (PH) assumption for total PA among women was not met; hence, we used the hv to calculate the hazard ratio. Total PA in women in the hv2 analysis was negatively associated with AF in all 3 models, although for hv1 no significant association was observed. The PH assumption for walking pace among men was not met, and none of the hv showed a statistically significant association between walking pace and AF in men.

CONCLUSIONS

These results suggest that PA is inversely associated with AF in women.

Excess of exercise increases the risk of atrial fibrillation

An interesting and still not well-understood example for old medical wisdom "Sola dosis facit venenum" is the increased prevalence of atrial fibrillation (AF) in athletes. Numerous studies have shown a fourfold to eightfold increased risk of AF in athletes compared to the normal population. Analysis of the existing data suggests a dose-dependent effect of exercise. Moderate exercise seems to have a protective effect and decreases the risk of AF, whereas excessive exercise seems to increase the risk of AF. The described cases illustrate clinical manifestations within the spectrum of AF in elderly athletes, that is, exercise-induced AF, vagal AF, chronic AF, and atrial flutter. As the arrhythmia worsened quality of life and exercise capacity in all patients, recovery of sinus rhythm was desired in all described cases. As the atrial disease was advanced on different levels, different treatment regimes were applied. Lifestyle modification and temporary anti-arrhythmic drug therapy could stabilize sinus rhythm in one patient, whereas others needed radiofrequency ablation to achieve a stable sinus rhythm. The patient with the most advanced atrial disease necessitated anti-arrhythmic drug therapy and another left atrial ablation. All described patients remained in sinus rhythm during the long-term follow-up.

Sex Differences in the Association Between Regular Physical Activity and Incident Atrial Fibrillation: A Meta-analysis of 13 Prospective Studies

Several studies investigated the role of physical activity in atrial fibrillation (AF), but the results remain controversial. We aimed to estimate the association between physical activity and incident AF, as well as to determine whether a sex difference existed. We systematically retrieved relevant studies from Cochrane Library, PubMed, and ScienceDirect through December 1, 2015. Data were abstracted from eligible studies and effect estimates pooled using a random-effects model. Thirteen prospective studies fulfilled inclusion criteria. For primary analysis, neither total physical activity exposure (relative risk [RR]: 0.98, 95% confidence interval [CI]: 0.90-1.06, P = 0.62) nor intensive physical activity (RR: 1.07, 95% CI: 0.93-1.25, P = 0.41) was associated with a significant increased risk of AF. In the country-stratified analysis, the pooled results were not significantly changed. However, in the sex-stratified analysis, total physical activity exposure was associated with an increased risk of AF in men (RR: 1.18, 95% CI: 1.02-1.37), especially at age <50 years (RR: 1.58, 95% CI: 1.28-1.95), with a significantly reduced risk of AF in women (RR: 0.92, 95% CI: 0.87-0.97). Additionally, male individuals with intensive physical activity had a slightly higher (although statistically nonsignificant) risk of developing AF (RR: 1.12, 95% CI: 0.99-1.28), but there was a significantly reduced risk of incident AF in women (RR: 0.92, 95% CI: 0.86-0.98). Published literature supports a sex difference in the association between physical activity and incident AF. Increasing physical activity is probably associated with an increased risk of AF in men and a decreased risk in women.

Sex differences in healthy human heart rate variability: A meta-analysis

The present meta-analysis aimed to quantify current evidence on sex differences in the autonomic control of the heart, indexed by measures of heart rate variability (HRV) in healthy human subjects. An extensive search of the literature yielded 2020 titles and abstracts, of which 172 provided sufficient reporting of sex difference in HRV. Data from 63,612 participants (31,970 females) were available for analysis. Meta-analysis yielded a total of 1154 effect size estimates (k) across 50 different measures of HRV in a cumulated total of 296,247 participants. Females showed a significantly lower mean RR interval and standard deviation of RR intervals (SDNN). The power spectral density of HRV in females is characterized by significantly less total power that contains significantly greater high- (HF) and less low-frequency (LF) power. This is further reflected by a lower LF/HF ratio. Meta-regression revealed significant effects of age, respiration control and the length of recording available for analysis. Although women showed greater mean heart rate, they showed greater vagal activity indexed by HF power of HRV. Underlying mechanisms of these findings are discussed.

Are There Deleterious Cardiac Effects of Acute and Chronic Endurance Exercise?

Multiple epidemiological studies document that habitual physical activity reduces the risk of atherosclerotic cardiovascular disease (ASCVD), and most demonstrate progressively lower rates of ASCVD with progressively more physical activity. Few studies have included individuals performing high-intensity, lifelong endurance exercise, however, and recent reports suggest that prodigious amounts of exercise may increase markers for, and even the incidence of, cardiovascular disease. This review examines the evidence that extremes of endurance exercise may increase cardiovascular disease risk by reviewing the causes and incidence of exercise-related cardiac events, and the acute effects of exercise on cardiovascular function, the effect of exercise on cardiac biomarkers, including "myocardial" creatine kinase, cardiac troponins, and cardiac natriuretic peptides. This review also examines the effect of exercise on coronary atherosclerosis and calcification, the frequency of atrial fibrillation in aging athletes, and the possibility that exercise may be deleterious in individuals genetically predisposed to such cardiac abnormalities as long QT syndrome, right ventricular cardiomyopathy, and hypertrophic cardiomyopathy. This review is to our knowledge unique because it addresses all known potentially adverse cardiovascular effects of endurance exercise. The best evidence remains that physical activity and exercise training benefit the population, but it is possible that prolonged exercise and exercise training can adversely affect cardiac function in some individuals. This hypothesis warrants further examination.

Gender differences in ventricular remodeling and function in college athletes, insights from lean body mass scaling and deformation imaging

Several studies suggest gender differences in ventricular dimensions in athletes. Few studies have, however, made comparisons of data indexed for lean body mass (LBM) using allometry. Ninety Caucasian college athletes (mixed sports) who were matched for age, ethnicity, and sport total cardiovascular demands underwent dual-energy x-ray absorptiometry scan for quantification of LBM. Athletes underwent comprehensive assessment of left and right ventricular and atrial structure and function using 2-dimensional echocardiography and deformation imaging using the TomTec analysis system. The mean age of the study population was 18.9 ± 1.9 years. Female athletes (n = 45) had a greater fat free percentage (19.4 ± 3.7%) compared to male athletes (11.5 ± 3.7%). When scaled to body surface area, male had on average 19 ± 3% (p <0.001) greater left ventricular (LV) mass; in contrast, when scaled to LBM, there was no significant difference in indexed LV mass -1.4 ± 3.0% (p = 0.63). Similarly, when allometrically scaled to LBM, there was no significant gender-based difference in LV or left atrial volumes. Although female athletes had mildly higher LV ejection fraction and LV global longitudinal strain in absolute value, systolic strain rate and allometrically indexed stroke volume were not different between genders (1.5 ± 3.6% [p = 0.63] and 0.0 ± 3.7% [p = 0.93], respectively). There were no differences in any of the functional atrial indexes including strain or strain rate parameters. In conclusion, gender-related differences in ventricular dimensions or function (stroke volume) appear less marked, if not absent, when indexing using LBM allometrically.

Bridging the gender gap in atrial fibrillation

Women have a similar lifetime prevalence of non-valvular atrial fibrillation (NVAF) compared with that of men. Given the significant morbidity and potential mortality associated with NVAF, it is crucial to understand gender differences with NVAF. Women can be more symptomatic than men. Despite a higher baseline stroke risk, they are less likely to be on anticoagulation. Women have a greater risk of thromboembolism and a similar rate of bleeding risk compared with men on anticoagulation. Initial experience suggests that novel oral anticoagulants have similar safety and efficacy profile in men and women. Although women can have more adverse reactions from antiarrhythmic therapies, they are often referred later than men for ablation. As a group, a mitigating factor in ablation referral is that women also have a higher incidence of procedural complications from catheter ablation. This review summarizes the available literature highlighting significant gender-based differences and also highlights areas for research to improve NVAF outcomes in women.

P-wave morphology is associated with echocardiographic response to cardiac resynchronization therapy in MADIT-CRT patients

BACKGROUND

In this study we hypothesized that signs of atypical atrial activation would be associated with cardiac resynchronization therapy (CRT) response in patients with mildly symptomatic heart failure (CHF), left ventricular dysfunction, and wide QRS complex.

METHODS

Patients included in the CRT-D arm in MADIT-CRT were studied (n = 892). Unfiltered signal-averaged P waves were analyzed to determine orthogonal P-wave morphology (typical morphologies were predefined as having positive signals in Leads X and Y and a negative or negative-positive signal in Lead Z. All other patterns were classified as atypical). The association between P-wave morphology and data on echocardiographic response at 1 year was analyzed.

RESULTS

Atypical P-wave morphology was found in 21% (n = 186) of the patients at baseline. Patients with atypical P-wave morphology were more often female (31% vs. 24%, P = 0.025), had lower BMI (28 ± 5 kg/m(2) vs. 29 ± 5 kg/m(2) , P = 0.008), had more ischemic CHF (60% vs. 52%, P = 0.026) and had smaller left atrial volumes (90 ± 20 mL vs. 94 ± 22 mL, P = 0.034). Atypical P-wave morphology at baseline was associated with superior response to CRT at 1 year with a larger reduction in left ventricular end-diastolic volume (-23 ± 12% vs. -20 ± 11%, P = 0.009), left ventricular end-systolic volume (-36 ± 16% vs. -31 ± 16%, P = 0.006), and left atrial volume (-31 ± 12% vs. -27 ± 12%, P = 0.005), with a slightly larger absolute increase in left ventricular ejection fraction (LVEF) (12 ± 5% vs. 11 ± 5%, P = 0.009). These associations were found to be independent of traditional predictors.

CONCLUSION

The presence of atypical P-wave morphology recorded is independently associated with a favorable echocardiographic cardiac remodeling response to CRT.

Increased prevalence of atrial fibrillation in the endurance athlete: potential mechanisms and sport specificity

Atrial fibrillation is a common, often symptomatic, and concerning arrhythmia that can lead to heart failure, decreased athletic tolerance, and thromboembolic events; it has also been associated with increased mortality. Although atrial fibrillation is an uncommon condition in younger and otherwise healthy people, recent emerging evidence indicates that endurance athletes may be at particularly high risk of developing atrial fibrillation. We review the evidence that atrial fibrillation is associated with intense endurance athletics and we also explore the mechanisms by which this may occur. Finally, we consider some of the options that are available to treat athletes who develop atrial fibrillation.