Acute impact of an endurance race on cardiac function and biomarkers of myocardial injury in triathletes with and without myocardial fibrosis

Impact of an Ultra-Endurance Marathon on Cardiac Function in Association with Cardiovascular Biomarkers

BACKGROUND

Participation in ultra-endurance races may lead to a transient decline in cardiac function and increased cardiovascular biomarkers. This study aims to assess alterations in biventricular function immediately and five days after the competition in relation to elevation of high-sensitivity cardiac Troponin I (hs-cTnI) and N-terminal-pro-brain-natriuretic-peptide (NT-proBNP).

METHODS AND RESULTS

Fifteen participants of an ultramarathon (UM) with a running distance of 130 km were included. Transthoracic echocardiography and quantification of biomarkers was performed before, immediately after and five days after the race. A significant reduction in right ventricular fractional area change (FAC) was observed after the race (48.0 ± 4.6% vs. 46.7 ± 3.8%, p = 0.011) that persisted five days later (48.0 ± 4.6% vs. 46.3 ± 3.9%, p = 0.027). No difference in left ventricular ejection fraction (LVEF) was found (p = 0.510). Upon stratification according to biomarkers, participants with NT-proBNP above the median had a significantly reduced LVEF directly (60.8 ± 3.6% vs. 56.9 ± 4.8%, p = 0.030) and five days after the race (60.8 ± 3.6% vs. 55.3 ± 4.5%, p = 0.007) compared to baseline values. FAC was significantly reduced five days after the race (48.4 ± 5.1 vs. 44.3 ± 3.9, p = 0.044). Athletes with hs-cTnI above the median had a significantly reduced FAC directly after the race (48.1 ± 4.6 vs. 46.5 ± 4.4, p = 0.038), while no difference in LVEF was observed. No alteration in cardiac function was observed if hs-cTnI or NT-proBNP was below the median.

CONCLUSION

A slight decline in cardiac function after prolonged strenuous exercise was observed in athletes with an elevation of hs-cTnI and NT-proBNP above the median but not below.

Exercise-induced cardiac troponin release in athletes with versus without coronary atherosclerosis

The magnitude of exercise-induced cardiac troponin (cTn) elevations is dependent on cardiovascular health status, and previous studies have shown that occult coronary atherosclerosis is highly prevalent among amateur athletes. We tested the hypothesis that middle-aged and older athletes with coronary atherosclerosis demonstrate greater cTn elevations following a controlled endurance exercise test compared with healthy peers. We included 59 male athletes from the Measuring Athletes' Risk of Cardiovascular events 2 (MARC-2) study and stratified them as controls [coronary artery calcium score (CACS) = 0, n = 20], high CACS [≥300 Agatston units or ≥75th Multi-Ethnic Study of Atherosclerosis (MESA) percentile, n = 20] or significant stenosis (≥50% in any coronary artery, n = 19). Participants performed a cycling test with incremental workload until volitional exhaustion. Serial high-sensitivity cTn (hs-cTn) T and I concentrations were measured (baseline, after 30-min warm-up, and 0, 30, 60, 120, and 180 min postexercise). There were 58 participants (61 [58-69] yr) who completed the exercise test (76 ± 14 min) with a peak heart rate of 97.7 [94.8-101.8]% of their estimated maximum. Exercise duration and workload did not differ across groups. High-sensitivity cardiac troponin T (Hs-cTnT) and high-sensitivity cardiac troponin I (hs-cTnI) concentrations significantly increased (1.55 [1.33-2.14]-fold and 2.76 [1.89-3.86]-fold, respectively) over time, but patterns of cTn changes and the incidence of concentrations >99th percentile did not differ across groups. Serial sampling of hs-cTnT and hs-cTnI concentrations during and following an exhaustive endurance exercise test did not reveal differences in exercise-induced cTn release between athletes with versus without coronary atherosclerosis. These findings suggest that a high CACS or a >50% stenosis in any coronary artery does not aggravate exercise-induced cTn release in middle-aged and older athletes.NEW & NOTEWORTHY Exercise-induced cardiac troponin (cTn) release is considered to be dependent on cardiovascular health status. We tested whether athletes with coronary atherosclerosis demonstrate greater exercise-induced cTn release compared with healthy peers. Athletes with coronary atherosclerosis did not differ in cTn release following exercise compared with healthy peers. Our findings suggest that a high CACS or a >50% stenosis in any coronary artery does not aggravate exercise-induced cTn release in middle-aged and older athletes.

Unrecognized myocardial scar by late-gadolinium-enhancement cardiovascular magnetic resonance: Insights from the population-based Hamburg City Health Study

BACKGROUND

The presence of myocardial scar is associated with poor prognosis in several underlying diseases. Late-gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging reveals clinically silent "unrecognized myocardial scar" (UMS), but the etiology of UMS often remains unclear. This population-based CMR study evaluated prevalence, localization, patterns, and risk factors of UMS.

METHODS

The study population consisted of 1064 consecutive Hamburg City Health Study participants without a history of coronary heart disease or myocarditis. UMS was assessed by standard-phase-sensitive-inversion-recovery LGE CMR.

RESULTS

Median age was 66 [quartiles 59, 71] years and 37% (388/1064) were females. UMS was detected in 244 (23%) participants. Twenty-five participants (10%) had ischemic, and 217 participants (89%) had non-ischemic scar patterns, predominantly involving the basal inferolateral left-ventricular (LV) myocardium (75%). Two participants (1%) had coincident ischemic and non-ischemic scar. The presence of any UMS was independently associated with LV ejection fraction (odds ratios (OR) per standard deviation (SD) 0.77 (confidence interval (CI) 0.65-0.90), p = 0.002) and LV mass (OR per SD 1.54 (CI 1.31-1.82), p < 0.001). Ischemic UMS was independently associated with LV ejection fraction (OR per SD 0.58 (CI 0.39-0.86), p = 0.007), LV mass (OR per SD 1.74 (CI 1.25-2.45), p = 0.001), and diabetes (OR 4.91 (CI 1.66-13.03), p = 0.002). Non-ischemic UMS was only independently associated with LV mass (OR per SD 1.44 (CI 1.24-1.69), p < 0.001).

CONCLUSION

UMS, in particular with a non-ischemic pattern, is frequent in individuals without known cardiac disease and predominantly involves the basal inferolateral LV myocardium. Presence of UMS is independently associated with a lower LVEF, a higher LV mass, and a history of diabetes.

CMR Mapping: The 4th-Era Revolution in Cardiac Imaging

Cardiac magnetic resonance (CMR) imaging has witnessed substantial progress with the advent of parametric mapping techniques, most notably T1 and T2 mapping. These advanced techniques provide valuable insights into a wide range of cardiac conditions, including ischemic heart disease, cardiomyopathies, inflammatory cardiomyopathies, heart valve disease, and athlete's heart. Mapping could be the first sign of myocardial injury and oftentimes precedes symptoms, changes in ejection fraction, and irreversible myocardial remodeling. The ability of parametric mapping to offer a quantitative assessment of myocardial tissue properties addresses the limitations of conventional CMR methods, which often rely on qualitative or semiquantitative data. However, challenges persist, especially in terms of standardization and reference value establishment, hindering the wider clinical adoption of parametric mapping. Future developments should prioritize the standardization of techniques to enhance their clinical applicability, ultimately optimizing patient care pathways and outcomes. In this review, we endeavor to provide insights into the potential contributions of CMR mapping techniques in enhancing the diagnostic processes across a range of cardiac conditions.

Cardiac magnetic resonance assessment of athletic myocardial fibrosis; Benign bystander or malignant marker?

The benefits of exercise are irrefutable with a well-established dose-dependent relationship between exercise intensity and reduction in cardiovascular disease. Differentiating the physiological adaptation to exercise, termed the "athlete's heart" from cardiomyopathies, has been advanced by the advent of more sophisticated imaging modalities such as cardiac magnetic resonance imaging (CMR). Myocardial fibrosis on CMR is a mutual finding amongst seemingly healthy endurance athletes and individuals with cardiomyopathy. As a substrate for arrhythmias, fibrosis is traditionally associated with increased cardiovascular risk. In this article, we discuss the aetiologies, distribution and potential implications of myocardial fibrosis in athletes.

Isolated myocardial edema in cardiac magnetic resonance - in search of a management strategy

Isolated myocardial edema not accompanied by late gadolinium enhancement (LGE) may be occasionally found on cardiac magnetic resonance (CMR). This type of picture may be encountered in patients with suspected myocarditis, post some acute cardiac events, with cardiac allograft rejection or even in athletes after an extreme exercise. Currently, there is no clear management strategy for this type of incidental finding. In this narrative review we discuss the methods and pitfalls of edema detection with means of CMR, review published data on isolated myocardial edema for each of the most probable clinical scenarios and propose a structured clinical decision-making algorithm to help clinicians navigate through this type of CMR result. Finally, we highlight the most important gaps in evidence related to isolated myocardial edema without fibrosis, where further research is particularly needed.

Exercise-induced myocardial T1 increase and right ventricular dysfunction in recreational cyclists: a CMR study

PURPOSE

Although cardiac troponin I (cTnI) increase following strenuous exercise has been observed, the development of exercise-induced myocardial edema remains unclear. Cardiac magnetic resonance (CMR) native T1/T2 mapping is sensitive to the pathological increase of myocardial water content. Therefore, we evaluated exercise-induced acute myocardial changes in recreational cyclists by incorporating biomarkers, echocardiography and CMR.

METHODS

Nineteen male recreational participants (age: 48 ± 5 years) cycled the 'L'étape du tour de France" (EDT) 2021' (175 km, 3600 altimeters). One week before the race, a maximal graded cycling test was conducted to determine individual heart rate (HR) training zones. One day before and 3-6 h post-exercise 3 T CMR and echocardiography were performed to assess myocardial native T1/T2 relaxation times and cardiac function, and blood samples were collected. All participants were asked to cycle 2 h around their anaerobic gas exchange threshold (HR zone 4).

RESULTS

Eighteen participants completed the EDT stage in 537 ± 58 min, including 154 ± 61 min of cycling time in HR zone 4. Post-race right ventricular (RV) dysfunction with reduced strain and increased volumes (p < 0.05) and borderline significant left ventricular global longitudinal strain reduction (p = 0.05) were observed. Post-exercise cTnI (0.75 ± 5.1 ng/l to 69.9 ± 41.6 ng/l; p < 0.001) and T1 relaxation times (1133 ± 48 ms to 1182 ± 46 ms, p < 0.001) increased significantly with no significant change in T2 (p = 0.474). cTnI release correlated with increase in T1 relaxation time (p = 0.002; r = 0.703), post-race RV dysfunction (p < 0.05; r = 0.562) and longer cycling in HR zone 4 (p < 0.05; r = 0.607).

CONCLUSION

Strenuous exercise causes early post-race cTnI increase, increased T1 relaxation time and RV dysfunction in recreational cyclists, which showed interdependent correlation. The long-term clinical significance of these changes needs further investigation.

TRIAL REGISTRATION NUMBERS AND DATE

NCT04940650 06/18/2021. NCT05138003 06/18/2021.

Prevalence and pattern of focal and potential diffuse myocardial fibrosis in male and female marathon runners using contrast-enhanced cardiac magnetic resonance

OBJECTIVES

This study analyzed the prevalence and pattern of focal and potential diffuse myocardial fibrosis detected by late gadolinium enhancement (LGE) and extracellular volume (ECV) imaging in male and female marathon runners using cardiac magnetic resonance (CMR).

METHODS

Seventy-four marathon runners were studied including 55 males (44 ± 8 years) and 19 females (36 ± 7 years) and compared to 36 controls with similar age and sex using contrast-enhanced CMR, exercise testing, and blood samples.

RESULTS

Contrast-enhanced CMR revealed focal myocardial fibrosis in 8 of 74 runners (11%). The majority of runners were male (7 of 8, 88%). LGE was typically non-ischemic in 7 of 8 runners (88%) and ischemic in one runner. ECV was higher in remote myocardium without LGE in male runners (25.5 ± 2.3%) compared to male controls (24.0 ± 3.0%, p < 0.05), indicating the potential presence of diffuse myocardial fibrosis. LV mass was higher in LGE + males (86 ± 18 g/m2) compared to LGE- males (73 ± 14 g/m2, p < 0.05). Furthermore, LGE + males had lower weight (69 ± 9 vs 77 ± 9 kg, p < 0.05) and shorter best marathon finishing times (3.2 ± 0.3 h) compared to LGE- males (3.6 ± 0.4 h, p < 0.05) suggesting higher training load in these runners to accomplish the marathon in a short time.

CONCLUSION

The high frequency of non-ischemic myocardial fibrosis in LGE + male runners can be related to increased LV mass in these runners. Furthermore, a higher training load could explain the higher LV mass and could be one additional cofactor in the genesis of myocardial fibrosis in marathon runners.

KEY POINTS

• A high frequency of myocardial fibrosis was found in marathon runners. • Myocardial fibrosis occurred typically in male runners and was typically non-ischemic. • Higher training load could be one cofactor in the genesis of myocardial fibrosis in marathon runners.

Left ventricular diastolic filling patterns in competitive triathletes with and without myocardial fibrosis by cardiac magnetic resonance time-volume analysis

PURPOSE

To investigate the influence of myocardial fibrosis on left ventricular (LV) diastolic filling patterns in triathletes compared to sedentary controls by cardiac magnetic resonance (CMR) imaging.

METHOD

101 male triathletes (43 ± 11 years) and 28 controls (41 ± 10 years) were recruited and underwent 1.5 T CMR including cine SSFP series, late gadolinium enhancement (LGE) imaging and T1 mapping. Functional and morphological parameters were obtained, and CMR-based LV diastolic filling parameters such as the early peak-filling rate (EPFR), atrial peak-filling rate (APFR) and peak-filling rate ratio (PFRR = EPFR/APFR) were determined by time-volume analysis of the cine series.

RESULTS

Non-ischemic LGE was detected in 20 triathletes (20 %) and in none of the controls. Compared to controls LGE-negative (LGE-) triathletes showed similar EPFR (216 ± 58 ml/s/m² vs 224 ± 69 ml/s/m², P = 0.52) but lower APFR (120 ± 46 ml/s/m² vs 147 ± 55 ml/s/m², P < 0.05), resulting in higher PFRR (2.1 ± 1 vs 1.6 ± 0.5, P < 0.01). LGE-positive (LGE + ) triathletes had similar EPFR (212 ± 73 ml/s/m², P = 0.798), but higher APFR (149 ± 50 ml/s/m², P < 0.05) and decreased PFRR (1.6 ± 0.7, P < 0.05) compared to LGE- triathletes. LGE + triathletes had increased LV mass index (88 ± 10 g/m² vs 80 ± 12 g/m², P < 0.01) and extracellular volume (ECV) fraction (26.2 ± 2.7 % vs 24.4 ± 1.7 %, P < 0.001) compared to LGE- triathletes.

CONCLUSIONS

Athletic activity leads to "supernormal" LV diastolic filling pattern in LGE- triathletes, which may be attributable to increased LV myocardial flexibility and elasticity. However, LGE + triathletes demonstrate a pseudo-normalization characterized by compensatory increase of atrial contraction. Possibly, due to reduced passive elasticity associated myocardial fibrosis.

Assessment of hepatic fat content and prediction of myocardial fibrosis in athletes by using proton density fat fraction sequence

PURPOSE

To explore the characteristics of the hepatic fat content in athletes, and predict late gadolinium enhancement (LGE) based on magnetic resonance imaging-proton density fat fraction (MRI-PDFF).

MATERIAL AND METHODS

From March 2020 to March 2021, 233 amateur athletes and 42 healthy sedentary controls were prospectively recruited. The liver fat content of four regions of interest (ROIs 1-4), the mean liver fat fraction (FF), cardiac function, and myocardium LGE were recorded, respectively. The values of ROIs 1-4 and FF were compared between athletes and controls. According to the liver fat content threshold for distinguishing athletes and controls, the cutoff total exercise time that induced a change in liver fat was obtained. The correlations among the liver fat content, cardiac function, and other parameters were analyzed. Moreover, the liver fat content was used to predict myocardium LGE by logistic regression.

RESULTS

There were significant differences for the values of ROI 1, ROI 3, ROI 4, and FF between athletes and controls (allp< 0.05). The cutoff total exercise time for inducing a change in the liver fat content was 1680 h (area under the curve [AUC] = 0.593, specificity = 83.3,p< 0.05). Blood indexes, cardiac function, and basic clinical parameters were related to liver fat content (allp< 0.05). The prediction model for LGE had an AUC value of 0.829 for the receiver operator characteristic curve.

CONCLUSION

MRI-PDFF could assess liver fat content and predict cardiac fibrosis in athletes for risk stratification and follow-up.

Cardiac Events in World-Class Athletes: An Internet-Based Study

PURPOSE

This study aimed at assessing the prevalence of adverse cardiac events, as identified in the media, in world-class athletes according to their sex and sports discipline.

METHODS

All female and male athletes from 30 individual Olympic sports who ranked in the international yearly top 10 between 2006 and 2018 were included. The name of each of them was associated in a Google search with selected key terms related to heart disease and/or acute cardiac events after their inclusion date. Global and sex-specific adverse cardiac event hazard function λ were calculated for each sport. Global and sex-specific prevalences of cardiac events were calculated, then compared (Fisher's exact test) between all sports.

RESULTS

From the 2471 athletes included, 15 cases of cardiac events (prevalence of 0.61%) were reported; 2 sudden cardiac deaths (0.08%) occurred in male athletes. The other events were related to arrhythmic events ( n = 13), mainly supraventricular arrhythmias ( n = 9). All surviving athletes were able to continue their career, mostly after ablation procedure. Male endurance athletes accounted for seven events, among which three events occurred among short-distance triathletes. Events among women were comparatively rare ( n = 4), and all were observed among short-distance triathletes.

CONCLUSIONS

A relatively unexpected high prevalence of cardiac events in endurance elite athletes was observed as compared with other sports, mainly, in short-distance male and female triathletes. This raises the question of particular cardiovascular constraints in this discipline and underlines the urge of international longitudinal follow-up studies in these kinds of athletes.

Hypertensive Response to Exercise in Athletes: Unremarkable Finding or Relevant Marker for Future Cardiovascular Complications?

Background. In the general population, hypertensive response to exercise (HRE) predicts new-onset resting hypertension or other cardiovascular diseases. Methods. PubMed was searched for English articles published between January 1st 2000 and April 30th 2020. Additional studies were identified via reference lists of included studies. 92 papers were selected for full text analysis, finally 30 studies were included. Results. The results from 5 follow-up studies suggested an association between HRE and the risk of developing hypertension, while 10 studies reported a link with adverse cardiovascular events in the general population. Another study showed an association between HRE and future hypertension in athletes after a follow-up of 7 years. HRE in athletes was associated with left ventricular hypertrophy in three studies. Two other studies showed a link between HRE and focal myocardial fibrosis in triathletes and myocardial injury, respectively. One study found lower Apoliprotein-1 serum levels in athletes with HRE leading to a higher risk for cardiovascular disease. Only in one study no association with cardiovascular dysfunction in athletes with HRE was found. Conclusions. Based on current evidence, HRE is not a normal finding in athletes. If detected, it should be interpreted as a risk factor for future cardiovascular complications. Future research should address the adequate follow-up and management of athletes with HRE.

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.

Limits of Cardiovascular Adaptation During an Extreme Ultramarathon: Insights From Serial Multidimensional, Multiparametric CMR

Extreme endurance athletic challenges provide unique opportunities to study the cardiovascular system's capacity for structural, functional, and hemodynamic adaptation. The authors present a case of a male subject who ran 2,469 km, with serial multiparametric cardiac magnetic resonance imaging used to demonstrate adaptive and maladaptive alterations in cardiac remodeling and myocardial tissue health. (Level of Difficulty: Advanced.).

Mild Left Ventricular Hypertrophy in Middle-Age Male Athletes as a Sign of Masked Arterial Hypertension

Mild left ventricular hypertrophy (LVH) has been considered as one of the possible structural, physiological adaptations to regular, intensive physical activity. However, it may also appear as one of the subclinical complications of hypertension. In athletes, the differential diagnosis between these two entities may be complicated as regular physical activity may potentially mask the presence of arterial hypertension. We sought to determine the relation between LVH in middle-age athletes and the presence of hypertension. The study included 71 healthy, male long-time amateur athletes (mean age 41 ± 6 years, 83% endurance and 17% power sports) without known hypertension or any other cardiovascular diseases and with normal self-measured and office blood pressure. All subjects underwent resting electrocardiogram, transthoracic echocardiography, maximal exercise test on a treadmill and ambulatory blood pressure monitoring. LVH was diagnosed as left ventricular wall diameter >11 mm. Hypertension was defined as mean 24 h systolic blood pressure (SBP) ≥ 130 mmHg and/or diastolic blood pressure (DBP) ≥ 80 mmHg. Exaggerated blood pressure response (EBPR) to exercise was defined as SBP ≥ 210 mmHg. LVH (range > 11 to 14 mm) was found in 20 subjects (28%) and hypertension was diagnosed in 33 subjects (46%). Athletes with LVH were more likely to have hypertension than those without LVH (70% vs. 37%, p = 0.01). EBPR to exercise was found equally common in athletes with and without LVH (35% vs. 29%, p = 0.68), but more often in subjects with hypertension (51% vs. 13%, p < 0.001). Presence of LVH and hypertension was equally common in the studied endurance and power sport athletes (p = 0.66 and p = 0.79, respectively). In comparison to athletes without LVH, those with LVH had larger left atrial size (26 ± 6 vs. 21 ± 4 cm2, p < 0.001) and a tendency for lower left ventricular diastolic function (E/A 1.2 ± 0.4 vs. 1.5 ± 0.4, p = 0.05) and a larger ascending aorta diameter (34 ± 3 vs. 32 ± 3, p = 0.05), but a similar left ventricular end-diastolic diameter (51 ± 3 vs. 51 ± 4, p = 0.71). The presence of mild left ventricular hypertrophy in middle-age male amateur athletes with normal home and office blood pressure may be considered as a potential sign of masked hypertension. It should not be overlooked as an element of a physiological adaptation to exercise and may warrant further medical evaluation with ambulatory blood pressure monitoring.

Exercise-induced myocardial edema in master triathletes: Insights from cardiovascular magnetic resonance imaging

Background

Strenuous exercise has been associated with functional and structural cardiac changes due to local and systemic inflammatory responses, reflecting oxidative, metabolic, hormonal, and thermal stress, even in healthy individuals. We aimed to assess changes in myocardial structure and function using cardiovascular magnetic resonance (CMR) imaging in master triathletes early after a full-distance Ironman Triathlon race.

Materials and methods

Ten master triathletes (age 45 ± 8 years) underwent CMR within 3 h after a full-distance Ironman Triathlon race (3.8 km swimming, 180 km cycling, and 42.2 km running) completed with a mean time of 12 ± 1 h. All the triathletes had a 30-day follow-up CMR. Cine balanced steady-state free precession, T2-short tau inversion recovery (STIR), tagging, and late gadolinium enhancement (LGE) imaging sequences were performed on a 1.5-T MR scanner. Myocardial edema was defined as a region with increased T2 signal intensity (SI) of at least two SDs above the mean of the normal myocardium. The extent of myocardial edema was expressed as the percentage of left ventricular (LV) mass. Analysis of LV strain and torsion by tissue tagging included the assessment of radial, longitudinal, and circumferential peak systolic strain, rotation, and twist.

Results

Compared with postrace, biventricular volumes, ejection fraction, and LV mass index remained unchanged at 30-day follow-up. Global T2 SI was significantly higher in the postrace CMR (postrace 10.5 ± 6% vs. follow-up 3.9 ± 3.8%, P = 0.004) and presented with a relative apical sparing distribution (P < 0.001) matched by reduction of radial peak systolic strain of basal segments (P = 0.003). Apical rotation and twist were significantly higher immediately after the competition compared with follow-up (P < 0.05).

Conclusion

Strenuous exercise in master triathletes is associated with a reversible regional increase in myocardial edema and reduction of radial peak systolic strain, both presenting with a relative apical sparing pattern.

T2 mapping in myocardial disease: a comprehensive review

Cardiovascular magnetic resonance (CMR) is considered the gold standard imaging modality for myocardial tissue characterization. Elevated transverse relaxation time (T2) is specific for increased myocardial water content, increased free water, and is used as an index of myocardial edema. The strengths of quantitative T2 mapping lie in the accurate characterization of myocardial edema, and the early detection of reversible myocardial disease without the use of contrast agents or ionizing radiation. Quantitative T2 mapping overcomes the limitations of T2-weighted imaging for reliable assessment of diffuse myocardial edema and can be used to diagnose, stage, and monitor myocardial injury. Strong evidence supports the clinical use of T2 mapping in acute myocardial infarction, myocarditis, heart transplant rejection, and dilated cardiomyopathy. Accumulating data support the utility of T2 mapping for the assessment of other cardiomyopathies, rheumatologic conditions with cardiac involvement, and monitoring for cancer therapy-related cardiac injury. Importantly, elevated T2 relaxation time may be the first sign of myocardial injury in many diseases and oftentimes precedes symptoms, changes in ejection fraction, and irreversible myocardial remodeling. This comprehensive review discusses the technical considerations and clinical roles of myocardial T2 mapping with an emphasis on expanding the impact of this unique, noninvasive tissue parameter.

Effect of High-Intensity Interval Training, Moderate Continuous Training, or Guideline-Based Physical Activity on Peak Oxygen Uptake and Myocardial Fibrosis in Patients With Myocardial Infarction: Protocol for a Randomized Controlled Trial

Introduction

High-intensity interval training (HIIT) is an emerging method of cardiac rehabilitation, which is more and more popular in recent years. Research into the effect of HIIT on peak oxygen uptake (VO₂ peak) and myocardial fibrosis among patients with myocardial infarction (MI) is lacking. Here, we describe the rationale along with the protocol for a clinical trial to test the following hypotheses: (1) compared with the control group, VO₂ peak will be increased in both the moderate-intensity continuous training (MICT) and HIIT groups and (2) compared with the control group, myocardial fibrosis due to MI will be improved by HIIT and MICT.

Methods and Analysis

This is a single-center, randomized controlled clinical trial. In total, 180 patients with MI are to be recruited for this study. VO₂ peak will be tested by cardiopulmonary exercise testing (CPET) and myocardial fibrosis will be evaluated by cardiac MR. A variety of blood and psychometric tests and also the peripheral arterial tonometry, reactive hyperemia index for microvascular endothelial function, and microvascular blockage or digital vasomotor response are included.

Ethics and Dissemination

The ethics committee of the Guangdong Provincial People's Hospital has authorized this mechanistic clinical research. Peer-reviewed articles and conference presentations will be used to disseminate the findings.

Trial Registration Number

NCT04863677.

Exercise-Induced Cardiac Troponin Elevations: From Underlying Mechanisms to Clinical Relevance

Supplemental Digital Content is available in the text.

Serological assessment of cardiac troponins (cTn) is the gold standard to assess myocardial injury in clinical practice. A greater magnitude of acutely or chronically elevated cTn concentrations is associated with lower event-free survival in patients and the general population. Exercise training is known to improve cardiovascular function and promote longevity, but exercise can produce an acute rise in cTn concentrations, which may exceed the upper reference limit in a substantial number of individuals. Whether exercise-induced cTn elevations are attributable to a physiological or pathological response and if they are clinically relevant has been debated for decades. Thus far, exercise-induced cTn elevations have been viewed as the only benign form of cTn elevations. However, recent studies report intriguing findings that shed new light on the underlying mechanisms and clinical relevance of exercise-induced cTn elevations. We will review the biochemical characteristics of cTn assays, key factors determining the magnitude of postexercise cTn concentrations, the release kinetics, underlying mechanisms causing and contributing to exercise-induced cTn release, and the clinical relevance of exercise-induced cTn elevations. We will also explain the association with cardiac function, correlates with (subclinical) cardiovascular diseases and exercise-induced cTn elevations predictive value for future cardiovascular events. Last, we will provide recommendations for interpretation of these findings and provide direction for future research in this field.

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.

Modulation of Cardiac Fibrosis in and Beyond Cells

The extracellular matrix (ECM) plays important roles in maintaining physiological structure and functions of various tissues and organs. Cardiac fibrosis is the excess deposition of ECM, including both fibrillar (collagens I and III) and non-fibrillar proteins. Characteristics of fibrosis can vary depending on the pathology, with focal fibrosis occurring following myocardial infarction (MI), and diffuse interstitial and perivascular fibrosis mainly in non-ischemic heart diseases. Compliance of the fibrotic tissue is significantly lower than the normal myocardium, and this can compromise the diastolic, as well as systolic dysfunction. Therefore, strategies to combat cardiac fibrosis have been investigated. Upon injury or inflammation, activated cardiac fibroblasts (myofibroblasts) produce more ECM proteins and cause fibrosis. The activation could be inhibited or the myofibroblasts could be ablated by targeting their specific expressed proteins. Modulation of tissue inhibitors of metalloproteinases (TIMPs) and moderate exercise can also suppress cardiac fibrosis. More recently, sex differences in cardiac fibrosis have come to light with differential fibrotic response in heart diseases as well as in fibroblast functions in vitro. This mini-review discusses recent progress in cardiac fibroblasts, TIMPs, sex differences and exercise in modulation of cardiac fibrosis.

Sudden cardiac death in sports: could we save Pheidippides?

Hereditary diseases under the age of 35 are the most common underlying heart disease, leading to sudden cardiac death (SCD) in competitive sports, while in older people, atherosclerotic coronary artery disease (CAD) is the main cause. The following preventive measures are recommended: (a) The pre-participation cardiovascular screening, (b) the genetic testing, (c) the use of implantable cardioverter-defibrillator (ICD), (d) the prohibition of doping in sports, (e) the prevention of 'exercise-induced' cardiac complications, (f) the reduction of high-risk factors for CAD, and (g) the use of cardiopulmonary resuscitation. The cost-effectiveness of the electrocardiograms in the pre-participation screening programs remains questionable. Genetic testing is recommended in borderline cases and positive family history. Athletes with ICD can, under certain conditions, participate in competitive sports. Excessive endurance exercise appears to harm the endothelium, promotes inflammatory processes and leads to fibrosis in the myocardium, and calcium deposition in the coronary vessels. Cardiac arrest may be reversed if cardiopulmonary resuscitation is performed and a defibrillator is immediately used. Thus, equipping all fields with automatic external defibrillators are recommended.

Decreased Native T1 Values and Impaired Myocardial Contractility in Anabolic Steroid Users

Anabolic androgenic steroid (AAS) abuse leads to myocardial toxicity. Human studies are conflicting about the myocardial fibrosis in AAS users. We evaluated cardiac tissue characterization, left ventricle (LV) function, and cardiac structure by cardiovascular magnetic resonance (CMR). Twenty strength-trained AAS users (AASU) aged 29±5 yr, 20 strength-trained AAS nonusers (AASNU), and 7 sedentary controls (SC) were enrolled. Native T1 mapping, late-gadolinium enhancement (LGE), extracellular volume (ECV), and myocardial strain were evaluated. AASU showed lower Native T1 values than AASNU (888±162 vs. 1020±179 ms p=0.047). Focal myocardial fibrosis was found in 2 AASU. AASU showed lower LV radial strain (30±8 vs. 38±6%, p<0.01), LV circumferential strain (-17±3 vs. -20±2%, p<0.01), and LV global longitudinal strain (-17±3 vs. -20±3%, p<0.01) than AASNU by CMR. By echocardiography, AASU demonstrated lower 4-chamber longitudinal strain than AASNU (-15±g3 vs. -18±2%, p=0.03). ECV was similar among AASU, AASNU, and SC (28±10 vs. 28±7 vs. 30±7%, p=0.93). AASU had higher LV mass index than AASNU and SC (85±14 vs. 64±8 vs. 58±5 g/m², respectively, p<0.01). AAS abuse may be linked to decreased myocardial native T1 values, impaired myocardial contractility, and focal fibrosis. These alterations may be associated with maladaptive cardiac hypertrophy in young AAS users.

Left Ventricular Fibrosis in Middle-Age Athletes and Physically Active Adults

INTRODUCTION

Cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE) and T1 mapping techniques enable the quantification of focal and diffuse myocardial LGE, respectively. Studies have shown evidence of fibrosis in middle-age athletes, but not relative to physically active (PA) adults who perform recommended physical activity levels. Therefore, we examined cardiac remodeling and presence of left ventricular (LV) LGE and T1 values in both recreational middle-age endurance athletes (EA) and PA adults.

METHODS

Healthy EA and PA adults (45-65 yr) completed a standardized 3-T CMR protocol with ventricular volumetry, LV LGE, and T1 mapping.

RESULTS

Seventy-two EA and 20 PA participants (mean age, 53 ± 5 vs 56 ± 4 yr; P < 0.01; V˙O2peak = 50 ± 7 vs 37 ± 9 mL·kg·min, P < 0.0001) were examined, with CMR data available in 89/92 participants. Focal LV LGE was observed in 30% of participants (n = 27/89): 33% of EA (n = 23/69; 33%) and 20% of PA (n = 4/20; 20%). LGE was present at the right ventricular hinge point (n = 21/89; 23.5%) or identified as ischemic (n = 2/89; 2%) or nonischemic (n = 4/89; 4%). Focal LV LGE was observed similarly in both EA and PA (P = 0.25). EA had larger LV chamber sizes and T1 native values (1169 ± 35 vs 1190 ± 26, P = 0.02) compared with PA, with similar LV ejection fraction. Global extracellular volume (ECV) was similar in both EA and PA (22.6% ± 3.5% vs 21.5% ± 2.6%, P = 0.26), with no relationship between global ECV and LV mass (r = -0.16, P = 0.19).

CONCLUSIONS

Focal LGE at the right ventricular hinge point was detected at the same frequency in both groups, was unrelated to demographic or clinical indices, and was found without evidence of global ECV expansion in EA, suggesting a physiologic remodeling response. The long-term clinical implications of hinge-point LGE require clarification using prospective, long-term follow-up studies.

Kinetics, Moderators and Reference Limits of Exercise-Induced Elevation of Cardiac Troponin T in Athletes: A Systematic Review and Meta-Analysis

Background: Kinetics, moderators and reference limits for exercise-induced cardiac troponin T (cTnT) elevations are still unclear. Methods: A systematic review of published literature was conducted adhering to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Studies reporting high-sensitivity cardiac troponin T (hs-cTnT) concentrations before and after a bout of exercise in athletes were included and analyzed. The final dataset consisted of 62 estimates from 16 bouts in 13 studies of 5-1,002 athletes (1,421 in total). Meta-analysis was performed using general linear mixed modeling and Bayesian inferences about effect magnitudes. Modifying fixed-effect moderators of gender, age, baseline level, exercise duration, intensity and modalities were investigated. Simulation was used to derive 99th percentile with 95% limits of upper reference ranges for hs-cTnT of athletic populations. Results: The mean and upper reference limits of hs-cTnT before exercise were 4.4 and 19 ng.L-1. Clear increases in hs-cTnT ranging from large to very large (factor changes of 2.1-7.5, 90% compatibility limits, ×/÷1.3) were evident from 0.7 through 25 h, peaking at 2.9 h after the midpoint of a 2.5-h bout of running, when the mean and upper reference limit for hs-cTnT were 33 and 390 ng L-1. A four-fold increase in exercise duration produced a large clear increase (2.4, ×/÷1.7) in post-exercise hs-cTnT. Rowing exercise demonstrated an extremely large clear reduction (0.1 ×/÷2.4). Conclusions: The kinetics of cTnT elevation following exercise, the positive effect of exercise duration, the impact of exercise modality and 99th upper reference limits for athletic populations were reasonably well defined by this meta-analysis.

Elevated peak systolic blood pressure in endurance-trained athletes: Physiology or pathology?

Blood pressure is a function of cardiac output and peripheral vascular resistance. During graded exercise testing (GXT), systolic blood pressure (SBP) is expected to increase gradually along with work rate, oxygen consumption, heart rate, and cardiac output. Individuals exposed to chronic endurance training attain a greater exercise SBP than in their untrained state and sedentary counterparts, but it is currently unknown what is considered a safe upper limit. This review discusses key studies examining blood pressure response in sedentary individuals and athletes. We highlight the physiological characteristics of highly fit individuals in terms of cardiovascular physiology and exercise blood pressure and review the state of the current literature regarding the safety of high SBP during exercise in this particular subgroup. Findings from this review indicate that a consensus on what is a normal SBP response to exercise in highly fit subjects and direct causation linking high GXT SBP to pathology is lacking. Consequently, applying GXT SBP guidelines developed for a "normal" population to endurance-trained individuals appears unsupported at this time. Lack of evidence for poor outcomes leads us to infer that elevated peak SBP in this subgroup could more likely reflect an adaptive response to training, rather than a pathological outcome. Future studies should track clinical outcomes of those achieving elevated SBP and develop athlete-specific guidelines.

Exercise-Induced Hypertension in Healthy Individuals and Athletes: Is it an Alarming Sign?

Exercise-induced hypertension (EIH) is defined as elevated blood pressure (BP) > 190mm Hg for females and > 210 mmHg for males during exercise. EIH is prevalent among athletes and healthy individuals with no cardiovascular (CV) risk factors. While previous data corroborates exercise in reducing hypertension and cardiovascular risk, the development of EIH and its attendant cardiovascular risk necessitates a review of the pathophysiological mechanisms resulting in EIH. To date, these mechanisms causing EIH are not fully understood, nor are there any established guidelines on the management of EIH. In this article, we discuss in detail the pathophysiological mechanisms, the prognostic value, clinical implications, possible treatment, and future directions in managing EIH.

Special Article - Exercise-induced right ventricular injury or arrhythmogenic cardiomyopathy (ACM): The bright side and the dark side of the moon

There is still debate on the range of normal physiologic changes of the right ventricle or ventricular (RV) function in athletes. Genetic links to arrhythmogenic cardiomyopathy (ACM) are well-established. There is no current consensus on the importance of extensive exercise and exercise-induced injury to the RV. During the intensive exercise of endurance sports, the cardiac structures adapt to athletic load over time. Some athletes develop RV cardiomyopathy possibly caused by genetic predisposition, whilst others develop arrhythmias from the RV. Endurance sports lead to increased volume and pressure load in both ventricles and increased myocardial mass. The extent of volume increase and changes in myocardial structure contribute to impairment of RV function and pose a challenge in cardiovascular sports medicine. Genetic predisposition to ACM may play an important role in the risk of sudden cardiac death of athletes. In this review, we discuss and evaluate existing results and opinions. Intensive training in competitive dynamic/power and endurance sports leads to specific RV adaptation, but physiological adaptation without genetic predisposition does not necessarily lead to severe complications in endurance sports. Discriminating between physiological adaptation and pathological form of ACM or RV impairment provoked by reinforced exercise presents a challenge to clinical sports cardiologists.