Acute, Exercise Dose-Dependent Impairment in Atrial Performance During an Endurance Race

Differences in cardiac adaptation to exercise in male and female athletes assessed by noninvasive techniques: a state-of-the-art review

Athlete's heart is generally regarded as a physiological adaptation to regular training, with specific morphological and functional alterations in the cardiovascular system. Development of the noninvasive imaging techniques over the past several years enabled better assessment of cardiac remodeling in athletes, which may eventually mimic certain pathological conditions with the potential for sudden cardiac death, or disease progression. The current literature provides a compelling overview of the available methods that target the interrelation of prolonged exercise with cardiac structure and function. However, this data stems from scientific studies that included mostly male athletes. Despite the growing participation of females in competitive sport meetings, little is known about the long-term cardiac effects of repetitive training in this population. There are several factors-biochemical, physiological and psychological, that determine sex-dependent cardiac response. Herein, the aim of this review was to compare cardiac adaptation to endurance exercise in male and female athletes with the use of electrocardiographic, echocardiographic, and biochemical examination, to determine the sex-specific phenotypes, and to improve the healthcare providers' awareness of cardiac remodeling in athletes. Finally, we discuss the possible exercise-induced alternations that should arouse suspicion of pathology and be further evaluated.

A case series of eight amateur athletes: exercise-induced pre-/syncope during the Zurich Marathon 2023

Background

Marathon running poses unique cardiovascular challenges, sometimes leading to syncopal episodes. We present a case series of athletes who experienced pre-/syncope during the Zurich Marathon 2023, accompanied by elevated cardiac biomarkers.

Case summary

Eight athletes (2 females, 6 males) aged 21-35 years, with pre-/syncope and various additional diverse symptoms such as dizziness and palpitations during the (half-)marathon, were admitted to two emergency departments in Zurich, Switzerland. Clinical evaluations included electrocardiogram, echocardiography, telemetry, coronary computed tomography (CT) scans, and cardiac biomarker assessments. High-sensitive troponin T (hs-cTnT) was elevated in all cases at initial assessment and returned to normal at follow-up. All athletes who received CT scans had normal coronary and brain CT results. None of the eight athletes had underlying cardiovascular disease. Renal function normalized post-admission, and neurological symptoms resolved within hours. Creatinine levels indicated transient acute kidney injury. A common feature was inexperience in running, inadequate race preparation, particularly regarding fluid, electrolyte, and carbohydrate intake, along with pacing issues and lack of coping strategies with heat.

Discussion

From a clinician perspective, the case series highlights the challenge in the management of patients with a pre-/syncopal event during strenuous exercise and elevated cardiac biomarkers. Diverse initial symptoms prompted tailored investigations. Adequate training, medical assessments, and awareness of syncope triggers are essential for marathon participants. Caution and pacing strategies are crucial, especially among novices in competitive running. This information is pertinent given the growing popularity of marathon events and prompts a standardized diagnostic approach after these events.

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

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

Impact of long-lasting moderate-intensity stage cycling event on cardiac function in young female athletes: A case study

PURPOSE

Effects of intense and/or prolonged exercise have been studied extensively in male athletes. Nevertheless, data are scare on the effect of long duration events on cardiac function in female athletes. Our aim was to investigate the effect of a long-lasting moderate-intensity stage cycling event on cardiac function of young female athletes.

METHODS

Seven well-trained female cyclists were included. They completed a cycling event of 3529 km on 23 days. All underwent an echocardiography on 6 time-points (baseline and at the arrival of day (D) 3, 7, 12, 13 and 23). Cardiac function was assessed by conventional echocardiography, tissue Doppler imaging and speckle tracking techniques. Daily exercise load was determined by heart rate (HR), power output and rate of perceived exertion data (RPE, Borg scale).

RESULTS

All stages were mainly done at moderate intensity (average HR: 65% of maximal, average aerobic power output: 36% of maximal, average RPE: 4). Resting HR measured at the time of echocardiography did not vary during the event. Resting cardiac dimensions did not significantly change during the 23 days of cycling. No significant modification of cardiac function, whatever the studied cavity, were observed all along the event.

CONCLUSION

The results suggest that, in the context of our case study, the long-lasting moderate-intensity stage cycling event was not associated with cardiac function alteration. Nevertheless, we must be careful in interpreting them due to the limits of an underpowered study.

Exercise-Induced Atrial Remodeling in Female Amateur Marathon Runners Assessed by Three-Dimensional and Speckle Tracking Echocardiography

Endurance athletes have an increased risk of atrial remodeling and atrial arrhythmias. However, data regarding atrial adaptation to physical exercise in non-elite athletes are limited. Even less is known about atrial performance in women. We aimed to elucidate exercise-induced changes in atrial morphology and function in female amateur marathon runners using three-dimensional (3D) echocardiography and two-dimensional (2D) speckle tracking echocardiography (STE). The study group consisted of 27 female (40 ± 7 years) amateur athletes. Right (RA) and left atrial (LA) measures were assessed three times: 2–3 weeks before the marathon (stage 1), immediately after the run (stage 2), and 2 weeks after the competition (stage 3). Directly after the marathon, a remarkable RA dilatation, as assessed by RA maximal volume (RAVmax, 31.3 ± 6.8 vs. 35.0 ± 7.0 ml/m²; p = 0.008), with concomitant increase in RA contractile function [RA active emptying fraction (RA active EF), 27.7 ± 8.6 vs. 35.0 ± 12.1%; p = 0.014; RA peak atrial contraction strain (RA PACS) 13.8 ± 1.8 vs. 15.6 ± 2.5%; p = 0.016] was noticed. There were no significant changes in LA volumes between stages, while LA active EF (34.3 ± 6.4 vs. 39.4 ± 8.6%; p = 0.020), along with LA PACS (12.8 ± 2.1 vs. 14.9 ± 2.7%; p = 0.002), increased post race. After the race, an increase in right ventricular (RV) dimensions (RV end-diastolic volume index, 48.8 ± 11.0 vs. 60.0 ± 11.1 ml/m²; p = 0.001) and a decrease in RV function (RV ejection fraction, 54.9 ± 6.3 vs. 49.1 ± 6.3%; p = 0.006) were observed. The magnitude of post-race RV dilatation was correlated with peak RA longitudinal strain deterioration (r = −0.56, p = 0.032). The measured parameters did not differ between stages 1 and 3. In female amateur athletes, apart from RV enlargement and dysfunction, marathon running promotes transient biatrial remodeling, with more pronounced changes in the RA. Post-race RA dilatation and increment of the active contraction force of both atria are observed. However, RA reservoir function diminishes in those with post-race RV dilation.

Right heart structure and function in lifelong recreational endurance athletes with and without paroxysmal atrial fibrillation

BACKGROUND

Healthy young athletes adapt to the increased demands of endurance exercise with symmetric cardiac remodeling. Male veteran endurance athletes have an increased risk of atrial fibrillation (AF), and some athletes seem susceptible to changes mimicking arrhythmogenic cardiomyopathy. Intense exercise puts a disproportionate hemodynamic load on the right-sided heart chambers. Despite this, data describing right heart structure and function in older veteran athletes are scarce. We aimed to investigate structural and functional characteristics of the right heart in veteran athletes with and without AF to contribute to the understanding of exercise-induced cardiac remodeling in this group.

METHODS

Three hundred and two male participants, of whom 151 were veteran skiers (62 with paroxysmal AF) and 151 were controls from the general population (62 with paroxysmal AF) underwent an echocardiographic examination in sinus rhythm to evaluate right atrial (RA) and right ventricular (RV) structure and function. While 87 of the participants had never exercised regularly, 50, 43, and 122 men had practiced regular endurance exercise for 1-20, 20-40, and >40 years, respectively.

RESULTS

RA volume and RV size increased with cumulative years of exercise (p<0.001), with a disproportionate increase in RV size compared with left ventricular (LV) size, regardless of AF status (p<0.001). RA and RV function assessed by strain remained similar despite lifelong exposure to endurance exercise. AF was associated with reduced RA strain irrespective of exposure to exercise (p<0.001).

CONCLUSION

RA and RV size and RV/LV ratio showed a dose-response relationship with cumulative years of endurance exercise, whereas RA and RV function did not. Indicating that increasing RV/LV ratio may represent a physiological adaptation to prolonged endurance exercise. AF was associated with reduced RA function, regardless of exposure to exercise, suggesting RA functional parameters are more closely linked to AF than RA size in veteran athletes.

Atrial fibrillation and sport: need for monitoring

Historically, regular exercise contributed to reduce the arrhythmic burden and improve cardiovascular outcomes in the general population. However, a heightened risk of Atrial Fibrillation (AF) seems to occur mainly amongst endurance athletes. The exact mechanisms are not fully elucidated, but dynamic interactions between electroanatomical changes induced by exercise, the autonomic system, variable triggers, along individual genetic predisposition are the main contributors to AF development in athletes. The type and training load of sports are also crucial in determining the arrhythmogenic milieu predisposing to AF insurgence and perpetuation. Moreover, a sex difference seems to influence an increased risk of AF only in men undergoing strenuous exercise, whereas women appear protected even during more vigorous training. In the absence of solid evidence, the advent of modern technologies could help to monitor and deep investigate the peculiar aspects of AF in these athletes. This review aims to describe the pathophysiology, diagnosis, and management of AF in athletes, shedding light on possible future strategies to face AF in this population.

The Acute Effects of an Ultramarathon on Atrial Function and Supraventricular Arrhythmias in Master Athletes

BACKGROUND

Endurance sports practice has significantly increased over the last decades, with a growing proportion of master athletes. However, concerns exist regarding the potential proarrhythmic effects induced by ultra-endurance sports. This study aimed to analyse the acute effects of an ultramarathon race on atrial remodelling and supraventricular arrhythmias in a population of master athletes.

METHODS

Master athletes participating in an ultramarathon (50 km, 600 m of elevation gain) with no history of heart disease were recruited. A single-lead ECG was recorded continuously from the day before to the end of the race. Echocardiography and 12-lead resting ECG were performed before and immediately at the end of the race.

RESULTS

The study sample consisted of 68 healthy non-professional master athletes. Compared with baseline, P wave voltage was higher after the race (p < 0.0001), and more athletes developed ECG criteria for right atrial enlargement (p < 0.0001). Most of the athletes (97%) had ≥1 premature atrial beats (PAB) during the 24-h monitoring, also organised in triplets (17%) and non-sustained supraventricular tachycardias (NSSVTs) (19%). In contrast, exercise-induced PABs, triplets, and NSSVTs were rare. One athlete developed acute atrial fibrillation during the race. After the race, no significant differences were found in biatrial dimensions. Biatrial function, estimated by peak atrial longitudinal and contraction strains, were normal both before and after the race.

CONCLUSIONS

In master athletes running an ultramarathon, acute exercise-induced atrial dysfunction was not detected, and exercise-induced supraventricular arrhythmias were uncommon. These results did not confirm the hypothesis of an acute atrial dysfunction induced by ultra-endurance exercise.

Exercise-Induced Cardiac Fatigue in Soldiers Assessed by Echocardiography

Background: Echocardiographic signs of exercise-induced cardiac fatigue (EICF) have been described after strenuous endurance exercise. Nevertheless, few data are available on the effects of repeated strenuous exercise, especially when associated with other constraints as sleep deprivation or mental stress which occur during military selection boot camps. Furthermore, we aimed to study the influence of experience and training level on potential EICF signs.

Methods: Two groups of trained soldiers were included, elite soldiers from the French Navy Special Forces (elite; n = 20) and non-elite officer cadets from a French military academy (non-elite; n = 38). All underwent echocardiography before and immediately after exposure to several days of uninterrupted intense exercise during their selection boot camps. Changes in myocardial morphology and function of the 4 cardiac chambers were assessed.

Results: Exercise-induced decrease in right and left atrial and ventricular functions were demonstrated with 2D-strain parameters in both groups. Indeed, both atrial reservoir strain, RV and LV longitudinal strain and LV global constructive work were altered. Increase in LV mechanical dispersion assessed by 2D-strain and alteration of conventional parameters of diastolic function (increase in E/e' and decrease in e') were solely observed in the non-elite group. Conventional parameters of LV and RV systolic function (LVEF, RVFAC, TAPSE, s mitral, and tricuspid waves) were not modified.

Conclusions: Alterations of myocardial functions are observed in soldiers after uninterrupted prolonged intense exercise performed during selection boot camps. These alterations occur both in elite and non-elite soldiers. 2D-strain is more sensitive to detect EICF than conventional echocardiographic parameters.

Acute impact of an endurance race on biventricular and biatrial myocardial strain in competitive male and female triathletes evaluated by feature-tracking CMR

Objectives

Cardiac adaptation in endurance athletes is a well-known phenomenon, but the acute impact of strenuous exercise is rarely reported on. The aim of this study was to analyze the alterations in biventricular and biatrial function in triathletes after an endurance race using novel feature-tracking cardiac magnetic resonance (FT-CMR).

Methods

Fifty consecutive triathletes (45 ± 10 years; 80% men) and twenty-eight controls were prospectively recruited, and underwent 1.5-T CMR. Biventricular and biatrial volumes, left ventricular ejection fraction (LVEF), FT-CMR analysis, and late gadolinium imaging (LGE) were performed. Global systolic longitudinal (GLS), circumferential (GCS), and radial strain (GRS) were assessed. CMR was performed at baseline and following an endurance race. High-sensitive troponin T and NT-proBNP were determined. The time interval between race completion and CMR was 2.3 ± 1.1 h (range 1–5 h).

Results

Post-race troponin T (p < 0.0001) and NT-proBNP (p < 0.0001) were elevated. LVEF remained constant (62 ± 6 vs. 63 ± 7%, p = 0.607). Post-race LV GLS decreased by tendency (− 18 ± 2 vs. − 17 ± 2%, p = 0.054), whereas GCS (− 16 ± 4 vs. − 18 ± 4%, p < 0.05) and GRS increased (39 ± 11 vs. 44 ± 11%, p < 0.01). Post-race right ventricular GLS (− 19 ± 3 vs. − 19 ± 3%, p = 0.668) remained constant and GCS increased (− 7 ± 2 vs. − 8 ± 3%, p < 0.001). Post-race left atrial GLS (30 ± 8 vs. 24 ± 6%, p < 0.0001) decreased while right atrial GLS remained constant (25 ± 6 vs. 24 ± 6%, p = 0.519).

Conclusions

The different alterations of post-race biventricular and biatrial strain might constitute an intrinsic compensatory mechanism following an acute bout of endurance exercise. The combined use of strain parameters may allow a better characterization of ventricular and atrial function in endurance athletes.

Key Points

• Triathletes demonstrate a decrease of LV global longitudinal strain by tendency and constant RV global longitudinal strain following an endurance race.

• Post-race LV and RV global circumferential and radial strains increase, possibly indicating a compensatory mechanism after an acute endurance exercise bout.

• Subgroup analyses of male triathletes with focal myocardial fibrosis did not demonstrate alterations in biventricular and biatrial strain after an endurance race.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08401-y.

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.

Cardiac adaptation to endurance exercise training: Differential impact of swimming and running

Objectives: High-intensity training has been associated with bi-ventricular and bi-atrial remodelling and a potentially increased risk of arrhythmias. Most of the evidence is based on endurance disciplines mainly involving the lower part of the body, while few data is available on upper body disciplines. The purpose of this study was to compare chronic cardiac remodelling induced by running and swimming as well as the acute response of ventricular and atrial performance after an upper-body and a lower-body endurance race. Methods: Standard and speckle tracking echocardiographic assessment of left ventricle, right ventricle and both atria was performed at baseline and immediately after a 9.5 km open-water swimming race in 26 healthy men and before and after a 35 km-trail-running race in 21 male runners. Results: No significant differences were observed in baseline ventricular dimensions. However, both right ventricular and atrial systolic deformation were greater in runners. This group also showed slightly larger atrial volumes as compared to swimmers. After the race, right ventricular dilatation was observed in both groups, but only runners showed a decrease in right ventricular deformation and a decrease in atrial volumes and deformation. Significant increases in atrial deformation without reduction in atrial volumes were observed only in swimmers after the race. Conclusions: Right ventricular and atrial remodelling is different depending on the endurance training discipline. Long-distance running races induce a greater impairment in right ventricular performance and atrial function compared to endurance swimming competitions.

Three-dimensional regional bi-ventricular shape remodeling is associated with exercise capacity in endurance athletes

AIMS

Endurance athletes develop cardiac remodeling to cope with increased cardiac output during exercise. This remodeling is both anatomical and functional and shows large interindividual variability. In this study, we quantify local geometric ventricular remodeling related to long-standing endurance training and assess its relationship with cardiovascular performance during exercise.

METHODS

We extracted 3D models of the biventricular shape from end-diastolic cine magnetic resonance images acquired from a cohort of 89 triathlon athletes and 77 healthy sedentary subjects. Additionally, the athletes underwent cardio-pulmonary exercise testing, together with an echocardiographic study at baseline and few minutes after maximal exercise. We used statistical shape analysis to identify regional bi-ventricular shape differences between athletes and non-athletes.

RESULTS

The ventricular shape was significantly different between athletes and controls (p < 1e-6). The observed regional remodeling in the right heart was mainly a shift of the right ventricle (RV) volume distribution towards the right ventricular infundibulum, increasing the overall right ventricular volume. In the left heart, there was an increment of left ventricular mass and a dilation of the left ventricle. Within athletes, the amount of such remodeling was independently associated to higher peak oxygen pulse (p < 0.001) and weakly with greater post-exercise RV free wall longitudinal strain (p = 0.03).

CONCLUSIONS

We were able to identify specific bi-ventricular regional remodeling induced by long-lasting endurance training. The amount of remodeling was associated with better cardiopulmonary performance during an exercise test.

Evaluation of Left Atrial Functions by 2-dimensional Speckle-Tracking Echocardiography During Healthy Pregnancy

OBJECTIVES

We aimed to determine the effects of normal pregnancy on left atrial (LA) mechanics using 2-dimensional speckle-tracking echocardiography.

METHODS

A total of 47 healthy women with singleton pregnancies were prospectively enrolled in this study. A total of 4 visits, including each trimester and postpartum at 6 months, were planned. Echocardiographic studies were performed with a Vivid 7 device equipped with a 2.5-MHz transducer (GE Vingmed Ultrasound AS, Horten, Norway).

RESULTS

Although the LA reservoir phase strain showed a gradual decrease from the first trimester to the third trimester during pregnancy, the measurements in the postpartum period were found to return to initial levels (mean ± SD: first trimester, 40.3% ± 11.7%; second trimester, 37.5% ± 12.9%; third trimester, 33.5% ± 9.0%; postpartum, 42.1% ± 11.1%; P < .001). The LA pump function strain was also parallel to the LA reservoir strain and gradually decreased from the first trimester to the third trimester during pregnancy, and it was observed that rose to the initial level in the postpartum period (first trimester, 16.7% ± 7.4%; second trimester, 14.8% ± 5.5%; third trimester, 12.7% ± 4.3%; postpartum, 15.8% ± 5.5%; P < .001).

CONCLUSIONS

We prospectively determined normal reference values for LA deformation parameters using speckle-tracking echocardiography in each trimester and the postpartum period in healthy pregnancy. These reference values may help identify subclinical LA dysfunction in several cardiovascular or systemic conditions. According to this study, these parameters decreased toward the third trimester during pregnancy and recovered in the postpartum period.

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.

Burden of premature atrial beats in middle-aged endurance athletes with and without lone atrial fibrillation versus sedentary controls

BACKGROUND

The burden of premature atrial beats (PABs) at 24-h electrocardiographic (ECG) monitoring correlates with the risk of atrial fibrillation. It is unknown whether prolonged and intense exercise increases the burden of PABs, thus contributing to the higher prevalence of atrial fibrillation observed in middle-aged athletes.

METHODS

We compared the burden of PABs at 24-h ECG monitoring off therapy in 134 healthy middle-aged (30-60-year-old) competitive athletes who had practised 9 (7-11) h of endurance sports for 8 (4-15) consecutive years, 134 age- and gender-matched healthy sedentary individuals, and 66 middle-aged patients (20 athletes and 46 non-athletes) with 'lone' paroxysmal atrial fibrillation.

RESULTS

More than 50 PABs/24 h or ≥1 run of ≥3 PABs were recorded in 23/134 (17%) healthy athletes and in 29/134 (22%) sedentary controls (p = 0.61). Healthy athletes with frequent or repetitive PABs were older (median 50 years vs. 43 years, p < 0.01) and had practised sport for a longer time (median 10 years vs. 6 years, p = 0.03). At multivariable analysis only age (odds ratio 1.11, 95% confidence interval 1.04-1.20, p < 0.01) remained an independent predictor of a higher burden of PABs. Also among patients with 'lone' paroxysmal atrial fibrillation, there was no difference in the prevalence of >50 PABs/24 h or ≥1 run of ≥3 PABs between athletes (40%) and controls (48%, p = 0.74).

CONCLUSIONS

Middle-aged endurance athletes, with or without paroxysmal atrial fibrillation, did not show a higher burden of PABs at 24-h ECG monitoring than sedentary controls. Age, but not intensity and duration of sports activity, predicted a higher burden of PABs among healthy athletes.

Cardiac performance after an endurance open water swimming race

PURPOSE

Endurance exercise competitions have shown a transient negative effect on global right ventricular (RV) performance. Most published studies are based on terrestrial sports. The aim of our study was to evaluate the cardiac effects after an open water swimming race.

METHODS

We evaluated 33 healthy swimmers (mean age 40.9 ± 7.2) participating in a 9.5 km open water swimming race. All subjects underwent a standard transthoracic echocardiography including an evaluation of dimensions and myocardial ventricular deformation. Echocardiography was performed 24 h before and within the first hour of arrival at the finish line. Cardiac troponin I (cTn I), NT-ProBNP and leukocytes were also evaluated.

RESULTS

No changes in left ventricle (LV) ejection fraction or LV global longitudinal strain were observed. A significant increase in RV end-diastolic area (RVEDA) was noted after the race (RVEDA at baseline 15.12 ± 1.86; RVEDA after race 16.06 ± 2.27, p < 0.05), but no changes were seen in RV fractional area change or RV global longitudinal strain. Cardiac biomarkers and leukocytes significantly increased. No association was detected between the increase in cTn I or NT-proBNP and the RV acute dilatation or LV performance. A significant association was observed between cTn I and leukocytes (r = 0.375, p < 0.05).

CONCLUSIONS

An acute RV dilatation but without an impairment in RV deformation was observed after participating in an endurance swimming race. The correlation between the increase in cTn I and leukocytes, but not with ventricular performance, may support the hypothesis of an exercise-induced increase in myocardial sarcolemmal permeability due to an inflammatory response rather than myocardial injury.

Left atrial functional response after a marathon in healthy amateur volunteers

Middle-aged marathon runners have an increased risk of developing atrial fibrillation (AF). A previous study described that repetitive marathon running was associated with left atrial (LA) dysfunction. However, whether this change is common in marathon runners and which runners are at risk of LA dysfunction remain unknown. The purpose of this study was to determine which factors could predict LA dysfunction. We prospectively examined 12 healthy amateur volunteers (9 males, 31 ± 8 years old) who participated in a full marathon. All echocardiographic measurements and speckle-tracking echocardiography were performed before and after the marathon. The endpoint was defined as reduced LA reservoir strain 1 day after the marathon (non-responder group). Seven participants were in the non-responder group. Age (35 ± 9 vs. 26 ± 2 years, p = 0.020), augmentation index (76 ± 12 vs. 55 ± 8, p = 0.002), and diastolic blood pressures (83 ± 11 vs. 70 ± 7 mmHg, p = 0.021) in the non-responder group were significantly higher compared with the responder group. In multivariate linear regression analysis, only the augmentation index was an independent predictor of reduced LA reservoir function after the marathon (β = - 0.646, p = 0.023). The augmentation index was a predictive marker for reduction in LA reservoir function after a marathon in healthy amateur volunteers.

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

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

Mechanisms of atrial fibrillation in athletes: what we know and what we do not know

Exercise is an emerging cause of atrial fibrillation (AF) in young individuals without coexisting cardiovascular risk factors. The causes of exercise-induced atrial fibrillation remain largely unknown, and conclusions are jeopardised by apparently conflicting data. Some components of the athlete's heart are known to be arrhythmogenic in other settings. Bradycardia, atrial dilatation and, possibly, atrial premature beats are therefore biologically plausible contributors to exercise-induced AF. Challenging findings in an animal model suggest that exercise might also prompt the development of atrial fibrosis, possibly due to cumulative minor structural damage after each exercise bout. However, there is very limited, indirect data supporting this hypothesis in athletes. Age, sex, the presence of comorbidities and cardiovascular risk factors, and genetic individual variability might serve to flag those athletes who are at the higher risk of exercise-induced AF. In this review, we will critically address current knowledge on the mechanisms of exercise-induced AF.

Gender influence on the adaptation of atrial performance to training

BACKGROUND

High-intensity training has been associated with atrial remodelling and arrhythmias in men. Our purpose was to analyse atrial performance in female endurance athletes, compared to male athletes and controls.

METHODS

This was a cross-sectional study. We included four groups: female athletes, females controls, male athletes and male controls. Left (LA) and right atrial (RA) volumes and function were assessed using 2D and speckle-tracking echocardiography to determine peak atrial strain-rate at atrial (SRa) and ventricular contraction (SRs), as surrogates of atrial contractile and reservoir function, respectively. ANOVA and Bonferroni's statistical tests were used to compare variables among groups.

RESULTS

We included 82 subjects, 39 women (19 endurance athletes, 20 controls) and 43 men (22 endurance athletes, 21 controls). Mean age was similar between groups (36.6 ± 5.6 years). Athletes had larger bi-atrial volumes, compared to controls (women, LA 27.1 vs. 15.8 ml/m², p < 0.001; RA 22.31 vs. 14.2 ml/m², p = 0.009; men, LA: 25.0 vs. 18.5 ml/m², p = 0.003; RA 30.8 vs. 21.9 ml/m², p < 0.001) and lower strain-rate (women, LASRa -1.60 vs. -2.18 s^-1, p < 0.001; RASRa -1.89 vs. -2.38 s^-1, p = 0.009; men, LASRa -1.21 vs. -1.44 s^-1, p = 1; RASRa -1.44 vs. -1.60 s^-1, p = 1). However, RA indexed size was lower and bi-atrial deformation greater in female athletes, compared to male athletes.

CONCLUSIONS

The atria of both male and female athletes shows specific remodelling, compared to sedentary subjects, with larger size and less deformation at rest, particularly for the RA. Despite a similar extent of remodelling, the pattern in women had greater bi-atrial myocardial deformation and smaller RA size.