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

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

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

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

Decreased cardiac reserve in asymptomatic patients after arterial switch operation for transposition of the great arteries

BACKGROUND

Exercise capacity is impaired in patients after arterial switch operation (ASO) for complete transposition of the great arteries. Maximal oxygen consumption is related with outcome.

OBJECTIVES

This study assessed ventricular function by advanced echocardiography and cardiac magnetic resonance (CMR) imaging at rest and during exercise, to determine exercise capacity in ASO patients, and to correlate exercise capacity with ventricular function as potential early marker of subclinical impairment.

METHODS

Forty-four patients (71% male, mean age 25 ± 4 years - range 18-40 years) were included during routine clinical follow-up. Assessment involved physical examination, 12‑lead ECG, echocardiography, and cardiopulmonary exercise test (CPET) (day 1). On day 2 CMR imaging at rest and during exercise was performed. Blood was sampled for biomarkers.

RESULTS

All patients reported New York Heart Association class I, the overall cohort had an impaired exercise capacity (80 ± 14% of predicted peak oxygen consumption). Fragmented QRS was present in 27%. Exercise CMR showed that 20% of patients had abnormal contractile reserve (CR) of the left ventricle (LV) and 25% had reduced CR of the right ventricle (RV). CR LV and CR RV were significantly associated with impaired exercise capacity. Pathological patterns on myocardial delayed enhancement and hinge point fibrosis were detected. Biomarkers were normal.

CONCLUSION

This study found that in some asymptomatic ASO patients electrical, LV and RV changes at rest, and signs of fibrosis are present. Maximal exercise capacity is impaired and seems to be linearly related to the CR of the LV and the RV. Therefore, exercise CMR might play a role in detecting subclinical deterioration of ASO patients.

Phenotyping heart failure by cardiac magnetic resonance imaging of cardiac macro- and microscopic structure: state of the art review

Heart failure demographics have evolved in past decades with the development of improved diagnostics, therapies, and prevention. Cardiac magnetic resonance (CMR) has developed in a similar timeframe to become the gold-standard non-invasive imaging modality for characterizing diseases causing heart failure. CMR techniques to assess cardiac morphology and function have progressed since their first use in the 1980s. Increasingly efficient acquisition protocols generate high spatial and temporal resolution images in less time. This has enabled new methods of characterizing cardiac systolic and diastolic function such as strain analysis, exercise real-time cine imaging and four-dimensional flow. A key strength of CMR is its ability to non-invasively interrogate the myocardial tissue composition. Gadolinium contrast agents revolutionized non-invasive cardiac imaging with the late gadolinium enhancement technique. Further advances enabled quantitative parametric mapping to increase sensitivity at detecting diffuse pathology. Novel methods such as diffusion tensor imaging and artificial intelligence-enhanced image generation are on the horizon. Magnetic resonance spectroscopy (MRS) provides a window into the molecular environment of the myocardium. Phosphorus (31P) spectroscopy can inform the status of cardiac energetics in health and disease. Proton (1H) spectroscopy complements this by measuring creatine and intramyocardial lipids. Hyperpolarized carbon (13C) spectroscopy is a novel method that could further our understanding of dynamic cardiac metabolism. CMR of other organs such as the lungs may add further depth into phenotypes of heart failure. The vast capabilities of CMR should be deployed and interpreted in context of current heart failure challenges.

Exercise stress cardiac magnetic resonance imaging in the assessment of induced cardiovascular responses in cardiac patients: a scoping review protocol

OBJECTIVE

This scoping review will describe cardiac magnetic resonance imaging testing protocols used in combination with exercise (Ex-CMR) to assess cardiovascular responses. The review will document the advantages and limitations of these protocols in cardiac patients.

INTRODUCTION

Ex-CMR characterizes the heart, differentiating between normal and pathological cardiac remodeling with considerable accuracy. However, there is no review detailing existing Ex-CMR protocols. This is particularly important since not all Ex-CMR protocols seem to induce enough stress to effectively characterize cardiac remodeling, hence the need for a review to report on the current evidence.

INCLUSION CRITERIA

This review will consider studies that use Ex-CMR testing protocols to assess cardiovascular responses, revealing cardiac remodeling in patients whose age at the time of the study was ≥ 18 years.

METHODS

The review will be conducted in accordance with the JBI methodology for scoping reviews and reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). The following databases will be searched: PubMed, Embase, ISI Web of Science, OpenGrey, Grey Matters, and OAlster. Articles in English and French will be included and there will be no limitation set for the date of publication. Data will be extracted from papers included in the scoping review by 2 independent reviewers and will be classified in summary tables.

REVIEW REGISTRATION

Open Science Framework https://osf.io/hvn75/?view_only=f6cf8fc2112e498d89c39639dbce70d1 .

Hypertrophic cardiomyopathy or athlete's heart? A systematic review of novel cardiovascular magnetic resonance imaging parameters

Hypertrophic cardiomyopathy (HCM) is a common cause of sudden cardiac death in athletes. Cardiac Magnetic Resonance (CMR) imaging is considered an excellent tool to differentiate between HCM and athlete's heart. The aim of this systematic review was to highlight the novel CMR-derived parameters with significant discriminative capacity between the two conditions. A systematic search in the MEDLINE, EMBASE and Cochrane Reviews databases was performed. Eligible studies were considered the ones comparing novel CMR-derived parameters on athletes and HCM patients. Therefore, studies that only examined Cine-derived volumetric parameters were excluded. Particular attention was given to binary classification results from multi-variate regression models and ROC curve analyses. Bias assessment was performed with the Quality Assessment on Diagnostic Accuracy Studies. Five (5) studies were included in the systematic review, with a total of 284 athletes and 373 HCM patients. Several novel indices displayed discriminatory potential, such as native T1 mapping and T2 values, LV global longitudinal strain, late gadolinium enhancement and whole-LV fractal dimension. Diffusion tensor imaging enabled quantification of the secondary eigenvalue angle and fractional anisotropy in one study, which also proved capable of reliably detecting HCM in a mixed athlete/patient sample. Several novel CMR-derived parameters, most of which are currently under development, show promising results in discerning between athlete's heart and HCM. Prospective studies examining the discriminatory capacity of all promising modalities side-by-side will yield definitive answers on their relative importance; diagnostic models can incorporate the best performing variables for optimal results.

Role of the electrocardiogram in differentiating genetically determined dilated cardiomyopathy from athlete's heart

BACKGROUND

Physiological cardiac remodelling in highly trained athletes may overlap with dilated cardiomyopathy (DCM).

OBJECTIVES

The aim of this study was to investigate the role of the electrocardiogram (ECG) in differentiating between physiological and pathological remodelling.

METHODS

The study population consisted of 30 patients with DCM who revealed a pathogenic variant at genetic testing and 30 elite athletes with significant cardiac remodelling defined by a left ventricular (LV) end-diastolic diameter >62 mm and/or LV ejection fraction between 45% and 50%.

RESULTS

The ECG was abnormal in 22 (73%) patients with DCM. The most common abnormalities were low voltages (n = 14, 47%), lateral T-wave inversion (TWI) (n = 6, 20%), ventricular ectopic beats (n = 5, 17%) and anterior TWI (n = 4, 13). Two athletes revealed an abnormal ECG: complete left bundle branch block (LBBB) in one case and atrial flutter in the other. The sensitivity, specificity and accuracy of the ECG in differentiating DCM from physiological adaptation to exercise in athletes was 73% (confidence interval [CI]: 54%-88%), 93% (CI: 78%-99%) and 0.83 (CI: 0.71-0.92) respectively.

CONCLUSIONS

While the ECG is usually normal in athletes exhibiting significant LV dilatation and/or systolic dysfunction, this test is often abnormal in patients with DCM harbouring a pathogenic variant. Low voltages in the limb leads and lateral TWI are the most common abnormalities.

Heart Failure With Preserved Ejection Fraction as an Exercise Deficiency Syndrome: JACC Focus Seminar 2/4

Across differing spectrums of cardiac function and cardiac pathologies, there are strong associations between measures of cardiorespiratory fitness and burden of symptoms, quality of life, and prognosis. In this part 2 of a 4-part series, we contend that there is a strong association among physical activity, cardiorespiratory fitness, and cardiac function. We argue that a chronic lack of exercise is a major risk factor for heart failure with preserved ejection fraction in some patients. In support of this hypothesis, increasing physical activity is associated with greater cardiac mass, greater stroke volumes, greater cardiac output and peak oxygen consumption, and fewer clinical events. Conversely, physical inactivity results in cardiac atrophy, reduced output, reduced chamber size, and decreased ability to augment cardiac performance with exercise. Moreover, physical inactivity is a strong predictor of heart failure risk and death. In sum, exercise deficiency should be considered part of the broad heart failure with preserved ejection fraction phenotype.

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

Background

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

Objectives

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

Methods

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

Results

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

Conclusion

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

Trial registration number

NCT05164328; ACTRN12618000716268.

Pressure-volume relationship by pharmacological stress cardiovascular magnetic resonance

The variation between rest and peak stress end-systolic pressure-volume relation (ΔESPVR) is an index of myocardial contractility, easily obtained during routine stress echocardiography and never tested during dipyridamole stress-cardiac magnetic resonance (CMR). We assessed the ΔESPVR index in patients with known/suspected coronary artery disease (CAD) who underwent dipyridamole stress-CMR. One-hundred consecutive patients (24 females, 63.76 ± 10.17 years) were considered. ESPVR index was evaluated at rest and stress from raw measurement of systolic arterial pressure and end-systolic volume by biplane Simpson's method. The ΔESPVR index showed a good inter-operator reproducibility. Mean ΔESPVR index was 0.48 ± 1.45 mmHg/mL/m2. ΔESPVR index was significantly lower in males than in females. ΔESPVR index was not correlated to rest left ventricular end-diastolic volume index or ejection fraction. Forty-six of 85 patients had myocardial fibrosis detected by the late gadolinium enhancement technique and they showed significantly lower ΔESPVR values. An abnormal stress CMR was found in 25 patients and they showed significantly lower ΔESPVR values. During a mean follow-up of 56.34 ± 30.04 months, 24 cardiovascular events occurred. At receiver-operating characteristic curve analysis, a ΔESPVR < 0.02 mmHg/mL/m2 predicted the presence of future cardiac events with a sensitivity of 0.79 and a specificity of 0.68. The noninvasive assessment of the ΔESPVR index during a dipyridamole stress-CMR exam is feasible and reproducible. The ΔESPVR index was independent from rest LV dimensions and function and can be used for a comparative assessment of patients with different diseases. ΔESPVR index by CMR can be a useful and simple marker for additional prognostic stratification.

Acute exercise-induced changes in cardiac function relates to right ventricular remodeling following 12-wk hypoxic exercise training

Repeated ventricular exposure to alterations in workload may relate to subsequent cardiac remodeling. We examined whether baseline acute changes in right (RV) and left ventricular (LV) function relate to chronic cardiac adaptation to 12-wk exercise training. Twenty-one healthy individuals performed 12-wk high-intensity endurance running training under hypoxia (fraction of inspired oxygen: 14.5%). Resting transthoracic echocardiography was performed before and after the training program to assess ventricular structure, function, and mechanics (including strain-area/volume loops). In addition, we examined systolic cardiac function during recumbent exercise under hypoxia at baseline (heart rate of 110-120 beats/min, "stress echocardiography"). Fifteen individuals completed training (22.0 ± 2.4 yr, 10 males). Hypoxic exercise training increased RV size, including diameter and area (all P < 0.05). With exception of an increase in RV fractional area change (P = 0.03), RV function did not change post-training (all P > 0.05). Regarding the RV strain-area loop, lower systolic and diastolic slopes were found post-training (P < 0.05). No adaptation in LV structure, function, or mechanics was observed (all P > 0.05). To answer our primary aim, we found that a greater increase in RV fractional area change during baseline stress echocardiography (r = -0.67, P = 0.01) inversely correlated with adaptation in RV basal diameter following 12-wk training. In conclusion, 12-wk high-intensity running hypoxic exercise training induced right-sided structural remodeling, which was, in part, related to baseline increase in RV fractional area change to acute exercise. These data suggest that acute cardiac responses to exercise may relate to subsequent RV remodeling after exercise training in healthy individuals.NEW & NOTEWORTHY During exercise, the right ventricle is exposed to a disproportionally higher wall stress than the left ventricle, which is further exaggerated under hypoxia. In this study, we showed that 12-wk high-intensity running hypoxic exercise training induced right-sided structural remodeling, which was, in part, related to baseline cardiac increase in RV fractional area change to acute exercise. These data suggest that acute RV responses to exercise are related to subsequent right ventricular remodeling in healthy individuals upon hypoxic training.

Endurance exercise and the risk of cardiovascular pathology in men: a comparison between lifelong and late-onset endurance training and a non-athletic lifestyle - rationale and design of the Master@Heart study, a prospective cohort trial

Introduction

Low and moderate endurance exercise is associated with better control of cardiovascular risk factors, a decreased risk of coronary artery disease and atrial fibrillation (AF). There is, however, a growing proportion of individuals regularly performing strenuous and prolonged endurance exercise in which the health benefits have been challenged. Higher doses of endurance exercise have been associated with a greater coronary atherosclerotic plaque burden, risk of AF and myocardial fibrosis (MF).

Methods and analysis

Master@Heart is a multicentre prospective cohort study aiming to assess the incidence of coronary atherosclerosis, AF and MF in lifelong endurance athletes compared to late-onset endurance athletes (initiation of regular endurance exercise after the age of 30 years) and healthy non-athletes.

The primary endpoint is the incidence of mixed coronary plaques. Secondary endpoints include coronary calcium scores, coronary stenosis >50%, the prevalence of calcified and soft plaques and AF and MF presence. Tertiary endpoints include ventricular arrhythmias, left and right ventricular function at rest and during exercise, arterial stiffness and carotid artery intima media thickness.

Two hundred male lifelong athletes, 200 late-onset athletes and 200 healthy non-athletes aged 45–70 will undergo comprehensive cardiovascular phenotyping using CT, coronary angiography, echocardiography, cardiac MRI, 12-lead ECG, exercise ECG and 24-hour Holter monitoring at baseline. Follow-up will include online tracking of sports activities, telephone calls to assess clinical events and a 7-day ECG recording after 1 year.

Ethics and dissemination

Local ethics committees approved the Master@Heart study. The trial was launched on 18 October 2018, recruitment is complete and inclusions are ongoing.

Trial registration number

NCT03711539.

Hydraulic force is a novel mechanism of diastolic function that may contribute to decreased diastolic filling in HFpEF and facilitate filling in HFrEF

A hydraulic force generated by blood moving the atrioventricular plane is a novel mechanism of diastolic function. The direction and magnitude of the force is dependent on the geometrical relationship between the left atrium and ventricle and is measured as the short-axis atrioventricular area difference (AVAD). In short, the net hydraulic force acts from a larger area toward a smaller one. It is currently unknown how cardiac remodeling affects this mechanism. The aim of the study was therefore to investigate this diastolic mechanism in patients with pathological or physiological remodeling. Seventy subjects [n = 11 heart failure with preserved ejection fraction (HFpEF), n = 10 heart failure with reduced ejection fraction (HFrEF), n = 7 signs of isolated diastolic dysfunction, n = 10 hypertrophic cardiomyopathy, n = 10 cardiac amyloidosis, n = 18 triathletes, and n = 14 controls] were included. Subjects underwent cardiac MR, and short-axis images of the left atrium and ventricle were delineated. AVAD was calculated as ventricular area minus atrial area and used as an indicator of net hydraulic force. At the onset of diastole, AVAD in HFpEF was -9.2 cm² (median) versus -4.4 cm² in controls, P = 0.02. The net hydraulic force was directed toward the ventricle for both but was larger in HFpEF. HFrEF was the only group with a positive median value (11.6 cm²), and net hydraulic force was throughout diastole directed toward the atrium. The net hydraulic force may impede cardiac filling throughout diastole in HFpEF, worsening diastolic dysfunction. In contrast, it may work favorably in patients with dilated ventricles and aid ventricular filling.NEW & NOTEWORTHY It is a previously unrecognized physiological mechanism of the heart that diastolic filling occurs with the help of hydraulics. In patients with heart failure with preserved ejection fraction, atrial dilatation may cause the net hydraulic force to work against cardiac filling, thus further augmenting diastolic dysfunction. In contrast, it may work favorably in patients with dilated ventricles, as in heart failure with reduced ejection fraction.

Exercise Cardiovascular Magnetic Resonance: A Review

While pharmacologic stress cardiovascular magnetic resonance imaging (MRI) is a robust noninvasive tool in the diagnosis and prognostication of epicardial coronary artery disease, clinical guidelines recommend exercise-based testing in those patients who can exercise. This review describes the development of exercise cardiovascular MRI protocols, summarizes the insights across various patient populations, and highlights future research initiatives. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 2.

Deformation Parameters of the Heart in Endurance Athletes and in Patients with Dilated Cardiomyopathy-A Cardiac Magnetic Resonance Study

A better understanding of the left ventricle (LV) and right ventricle (RV) functioning would help with the differentiation between athlete's heart and dilated cardiomyopathy (DCM). We aimed to analyse deformation parameters in endurance athletes relative to patients with DCM using cardiac magnetic resonance feature tracking (CMR-FT). The study included males of a similar age: 22 ultramarathon runners, 22 patients with DCM and 21 sedentary healthy controls (41 ± 9 years). The analysed parameters were peak LV global longitudinal, circumferential and radial strains (GLS, GCS and GRS, respectively); peak LV torsion; peak RV GLS. The peak LV GLS was similar in controls and athletes, but lower in DCM (p < 0.0001). Peak LV GCS and GRS decreased from controls to DCM (both p < 0.0001). The best value for differentiation between DCM and other groups was found for the LV ejection fraction (area under the curve (AUC) = 0.990, p = 0.0001, with 90.9% sensitivity and 100% specificity for ≤53%) and the peak LV GRS diastolic rate (AUC = 0.987, p = 0.0001, with 100% sensitivity and 88.4% specificity for >-1.27 s^-1). The peak LV GRS diastolic rate was the only independent predictor of DCM (p = 0.003). Distinctive deformation patterns that were typical for each of the analysed groups existed and can help to differentiate between athlete's heart, a nonathletic heart and a dilated cardiomyopathy.

Exercise right ventricular ejection fraction predicts right ventricular contractile reserve

BACKGROUND

Right ventricular (RV) contractile reserve shows promise as an indicator of occult RV dysfunction in pulmonary vascular disease. We investigated which measure of RV contractile reserve during exercise best predicts occult RV dysfunction and clinical outcomes.

METHODS

We prospectively studied RV contractile reserve in 35 human subjects referred for right heart catheterization for known or suspected pulmonary hypertension. All underwent cardiac magnetic resonance imaging, echocardiography, and supine invasive cardiopulmonary exercise testing with concomitant RV pressure-volume catheterization. Event-free survival was prospectively adjudicated from time of right heart catheterization for a 4-year follow-up period.

RESULTS

RV contractile reserve during exercise, as measured by a positive change in end-systolic elastance (Ees) during exertion, was associated with elevation in pulmonary pressures but preservation of RV volumes. Lack of RV reserve, on the other hand, was tightly coupled with acute RV dilation during exertion (R² = 0.76, p< 0.001). RV Ees and dilation changes each predicted resting RV-PA dysfunction. RV ejection fraction during exercise, which captured exertional changes in both RV Ees and RV dilation, proved to be a robust surrogate for RV contractile reserve. Reduced exercise RV ejection fraction best predicted occult RV dysfunction among a variety of resting and exercise RV measures, and was also associated with clinical worsening.

CONCLUSIONS

RV ejection fraction during exercise, as an index of RV contractile reserve, allows for excellent identification of occult RV dysfunction, more so than resting measures of RV function, and may predict clinical outcomes as well.

Screening of Potential Cardiac Involvement in Competitive Athletes Recovering From COVID-19: An Expert Consensus Statement

As our understanding of the complications of coronavirus disease-2019 (COVID-19) evolve, subclinical cardiac pathology such as myocarditis, pericarditis, and right ventricular dysfunction in the absence of significant clinical symptoms represents a concern. The potential implications of these findings in athletes are significant given the concern that exercise, during the acute phase of viral myocarditis, may exacerbate myocardial injury and precipitate malignant ventricular arrhythmias. Such concerns have led to the development and publication of expert consensus documents aimed at providing guidance for the evaluation of athletes after contracting COVID-19 in order to permit safe return to play. Cardiac imaging is at the center of these evaluations. This review seeks to evaluate the current evidence regarding COVID-19-associated cardiovascular disease and how multimodality imaging may be useful in the screening and clinical evaluation of athletes with suspected cardiovascular complications of infection. Guidance is provided with diagnostic "red flags" that raise the suspicion of pathology. Specific emphasis is placed on the unique challenges posed in distinguishing athletic cardiac remodeling from subclinical cardiac disease. The strengths and limitations of different imaging modalities are discussed and an approach to return to play decision making for athletes post-COVID-19, as informed by multimodality imaging, is provided.

Exercise cardiovascular magnetic resonance: development, current utility and future applications

Stress cardiac imaging is the current first line investigation for coronary artery disease diagnosis and decision making and an adjunctive tool in a range of non-ischaemic cardiovascular diseases. Exercise cardiovascular magnetic resonance (Ex-CMR) has developed over the past 25 years to combine the superior image qualities of CMR with the preferred method of exercise stress. Presently, numerous exercise methods exist, from performing stress on an adjacent CMR compatible treadmill to in-scanner exercise, most commonly on a supine cycle ergometer. Cardiac conditions studied by Ex-CMR are broad, commonly investigating ischaemic heart disease and congenital heart disease but extending to pulmonary hypertension and diabetic heart disease. This review presents an in-depth assessment of the various Ex-CMR stress methods and the varied pulse sequence approaches, including those specially designed for Ex-CMR. Current and future developments in image acquisition are highlighted, and will likely lead to a much greater clinical use of Ex-CMR across a range of cardiovascular conditions.

Differentiating Athlete's Heart from Left Ventricle Cardiomyopathies

Imaging techniques have allowed knowing the structural adaptative changes observed in the hearts of highly trained athletes. Athletes can develop very marked structural changes and the need may rise for a differential diagnosis with real cardiomyopathy. In this chapter, authors review the physiologic and morphologic features associated with athletic training and the keys to differentiate normal adaptive athlete's heart from mild or initial expression forms of left-heart side cardiomyopathies such as hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and left ventricle non-compaction (LVNC).

Differentiation between athlete’s heart and dilated cardiomyopathy in athletic individuals

Objective

Distinguishing early dilated cardiomyopathy (DCM) from physiological left ventricular (LV) dilatation with LV ejection fraction <55% in athletes (grey zone) is challenging. We evaluated the role of a cascade of investigations to differentiate these two entities.

Methods

Thirty-five asymptomatic active males with DCM, 25 male athletes in the ‘grey zone’ and 24 male athletes with normal LV ejection fraction underwent N-terminal pro-brain natriuretic peptide (NT-proBNP) measurement, ECG and exercise echocardiography. Grey-zone athletes and patients with DCM underwent cardiovascular magnetic resonance (CMR) and Holter monitoring.

Results

Larger LV cavity dimensions and lower LV ejection fraction were the only differences between grey-zone and control athletes. None of the grey-zone athletes had abnormal NT-proBNP, increased ectopic burden/complex arrhythmias or pathological late gadolinium enhancement on CMR. These features were also absent in 71%, 71% and 50% of patients with DCM, respectively. 95% of grey-zone athletes and 60% of patients with DCM had normal ECG. During exercise echocardiography, 96% grey-zone athletes increased LV ejection fraction by >11% from baseline to peak exercise compared with 23% of patients with DCM (p<0.0001). Peak LV ejection fraction was >63% in 92% grey-zone athletes compared with 17% patients with DCM (p<0.0001). Failure to increase LV ejection fraction >11% from baseline to peak exercise or achieve a peak LV ejection fraction >63% had sensitivity of 77% and 83%, respectively, and specificity of 96% and 92%, respectively, for predicting DCM.

Conclusion

Comprehensive assessment using a cascade of routine investigations revealed that exercise stress echocardiography has the greatest discriminatory value in differentiating between grey-zone athletes and asymptomatic patients with DCM. Our findings require validation in larger studies.

The Significance of "Contractile Reserve" in the Echocardiographic Assessment of Athletic Heart Syndrome

The clinical distinction between athlete's heart and structural heart disease in the echocardiography laboratory is often challenging. We present a case where athletic heart syndrome was promptly differentiated from pathology with a simple maneuver during echocardiography.

Left ventricular remodeling in elite and sub-elite road cyclists

Marked adaptation of left ventricular (LV) structure in endurance athletes is well established. However, previous investigations of functional and mechanical adaptation have been contradictory. A lack of clarity in subjects' athletic performance level may have contributed to these disparate findings. This study aimed to describe structural, functional, and mechanical characteristics of the cyclists' LV, based on clearly defined performance levels. Male elite cyclists (EC) (n = 69), sub-elite cyclists (SEC) (n = 30), and non-athletes (NA) (n = 46) were comparatively studied using conventional and speckle tracking 2D echocardiography. Dilated eccentric hypertrophy was common in EC (34.7%), but not SEC (3.3%). Chamber concentricity was higher in EC compared to SEC (7.11 ± 1.08 vs 5.85 ± 0.98 g/(mL)^2/3 , P < .001). Ejection fraction (EF) was lower in EC compared to NA (57 ± 5% vs 59 ± 4%, P < .05), and reduced EF was observed in a greater proportion of EC (11.6%) compared to SEC (6.7%). Global circumferential strain (GCε) was greater in EC (-18.4 ± 2.4%) and SEC (-19.8 ± 2.7%) compared to NA (-17.2 ± 2.6%) (P < .05 and P < .001). Early diastolic filling was lower in EC compared with SEC (0.72 ± 0.14 vs 0.88 ± 0.12 cm/s, P < .001), as were septal E' (12 ± 2 vs 15 ± 2 cm/s, P < .001) and lateral E' (18 ± 4 vs 20 ± 4 cm/s, P < .05). The magnitude of LV structural adaptation was far greater in EC compared with SEC. Increased GCε may represent a compensatory mechanism to maintain stroke volume in the presence of increased chamber volume. Decreased E and E' velocities may be indicative of a considerable functional reserve in EC.

The Utility of Cardiac Reserve for the Early Detection of Cancer Treatment-Related Cardiac Dysfunction: A Comprehensive Overview

With progressive advancements in cancer detection and treatment, cancer-specific survival has improved dramatically over the past decades. Consequently, long-term health outcomes are increasingly defined by comorbidities such as cardiovascular disease. Importantly, a number of well-established and emerging cancer treatments have been associated with varying degrees of cardiovascular injury that may not emerge until years following the completion of cancer treatment. Of particular concern is the development of cancer treatment related cardiac dysfunction (CTRCD) which is associated with an increased risk of heart failure and high risk of morbidity and mortality. Early detection of CTRCD appears critical for preventing long-term cardiovascular morbidity in cancer survivors. However, current clinical standards for the identification of CTRCD rely on assessments of cardiac function in the resting state. This provides incomplete information about the heart's reserve capacity and may reduce the sensitivity for detecting sub-clinical myocardial injury. Advances in non-invasive imaging techniques have enabled cardiac function to be quantified during exercise thereby providing a novel means of identifying early cardiac dysfunction that has proved useful in several cardiovascular pathologies. The purpose of this narrative review is (1) to discuss the different non-invasive imaging techniques that can be used for quantifying different aspects of cardiac reserve; (2) discuss the findings from studies of cancer patients that have measured cardiac reserve as a marker of CTRCD; and (3) highlight the future directions important knowledge gaps that need to be addressed for cardiac reserve to be effectively integrated into routine monitoring for cancer patients exposed to cardiotoxic therapies.

The year 2018 in the European Heart Journal-Cardiovascular Imaging: Part II

European Heart Journal - Cardiovascular Imaging was launched in 2012 as a multimodality cardiovascular imaging journal. It has gained an impressive impact factor during its first 5 years and is now established as one of the top cardiovascular journals and has become the most important cardiovascular imaging journal in Europe. The most important studies from 2018 will be highlighted in two reports. Part I of the review has focused on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on cardiomyopathies, congenital heart diseases, valvular heart diseases, and heart failure.

Advanced Imaging to Phenotype Patients With a Systemic Right Ventricle

Background

Reduced ventricular function and decreased exercise capacity are widespread in adults with complete transposition of the great arteries after atrial switch (TGA‐Mustard/Senning) and congenitally corrected TGA (ccTGA). Advanced imaging techniques may help to better phenotype these patients and evaluate exercise cardiac response.

Methods and Results

Thirty‐three adults with a systemic right ventricle (70% TGA‐Mustard/Senning, 37±9 years of age, 24% female, 94% New York Heart Association class I‐II) underwent echocardiogram, cardiopulmonary exercise testing, and cardiovascular magnetic resonance imaging at rest and during a 4‐stage free‐breathing bicycle test. They were compared with 12 healthy controls (39±10 years of age, 25% female, all New York Heart Association class I). TGA‐Mustard/Senning patients had a higher global circumferential strain (−15.8±3.6 versus −11.2±5.2%, P=0.008) when compared with ccTGA, whereas global longitudinal strain and systemic right ventricle contractility during exercise were similar in both groups. Septal extracellular volume (ECV) in ccTGA was significantly higher than in TGA‐Mustard/Senning (30.2±2.0 versus 27.1±2.7%, P=0.005). During exercise, TGA‐Mustard/Senning had a fall in end‐diastolic volume and stroke volume (11% and 8%, respectively; both P≤0.002), whereas ccTGA could increase their stroke volume in the same way as healthy controls. Because of a greater heart rate reserve in TGA‐Mustard/Senning (P for interaction=0.010), cardiac index and peak oxygen uptake were similar between both patient groups.

Conclusions

Caution should be exercised when evaluating pooled analyses of systemic right ventricle patients, given the differences in myocardial contraction pattern, septal extracellular volume, and the exercise response of TGA‐Mustard/Senning versus ccTGA patients. Longitudinal follow‐up will determine whether abnormal exercise cardiac response is a marker of earlier failure.

The year 2018 in the European Heart Journal - Cardiovascular Imaging: Part I

The European Heart Journal - Cardiovascular Imaging has become one of the leading multimodality cardiovascular imaging journal, since it was launched in 2012. The impact factor is an impressive 8.366 and it is now established as one of the top 10 cardiovascular journals. The journal is the most important cardiovascular imaging journal in Europe. The most important studies from 2018 will be highlighted in two reports. Part I of the review will focus on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on valvular heart disease, heart failure, cardiomyopathies, and congenital heart disease.

Athlete's Heart: Diagnostic Challenges and Future Perspectives

Distinguishing between adaptive and maladaptive cardiovascular response to exercise is crucial to prevent the unnecessary termination of an athlete's career and to minimize the risk of sudden death. This is a challenging task essentially due to the substantial phenotypic overlap between electrical and structural changes seen in the physiological athletic heart remodeling and pathological changes seen in inherited or acquired cardiomyopathies. Stress testing is an ideal tool to discriminate normal from abnormal cardiovascular response by unmasking subtle pathologic responses otherwise undetectable at rest. Treadmill or bicycle electrocardiography, transthoracic echocardiography, and cardiopulmonary exercise testing are common clinical investigations used in sports cardiology, specifically among participants presenting with resting electrocardiographic abnormalities, frequent premature ventricular beats, or non-sustained ventricular arrhythmias. In this setting, as well as in cases of left ventricular hypertrophy or asymptomatic left ventricular dysfunction, stress imaging and myocardial tissue characterization by cardiovascular magnetic resonance show promise. In this review, we aimed to reappraise current diagnostic schemes, screening strategies and novel approaches that may be used to distinguish adaptive remodeling patterns to physical exercise from early phenotypes of inherited or acquired pathological conditions commanding prompt intervention.

Resting and Exercise Doppler Hemodynamics: How and Why?

Exercise intolerance is the clinical hallmark of the failing heart. Evidence of hemodynamic derangement is not always present at rest, often necessitating dynamic challenges to accentuate abnormalities. Although cardiac catheterization, particularly with exercise, remains the gold standard method for hemodynamic assessment, it is limited by practicality, access, risk, and its invasive nature; consequently, there is a need to better understand noninvasive measures. Echocardiography and cardiac MRI offer promising modalities to quantify ventriculo-vascular interactions. Significant heterogeneity exists around exercise protocols, and there is a need to develop consensus methodology and to validate these noninvasive measures in all forms of heart failure.

Left Ventricular Trabeculations in Athletes: Epiphenomenon or Phenotype of Disease?

PURPOSE OF REVIEW

Excessive trabeculation attracting a diagnosis of left ventricular noncompaction cardiomyopathy (LVNC) has been reported in ostensibly healthy athletes. This review aims to explain why this occurs and whether this represents a spectrum of athletic physiological remodelling or unmasking of occult cardiomyopathy.

RECENT FINDINGS

Genetic studies have yet to identify a dominant mutation associated with the LVNC phenotype and reported gene mutations overlap with many distinct cardiomyopathies and ion channel disorders, implying that the phenotype is shared across different genetic conditions. Large contemporary cohort studies indicate that current LVNC imaging criteria are oversensitive and not predictive of adverse clinical outcomes. The majority of excessive LV trabeculation, as assessed by current quantification methods, is not due to cardiomyopathy but forms part of the normal continuum in health with potential contributions from cardiac remodelling processes. The study of rare, severe LVNC phenotypes may yield insights into an underlying molecular pathogenesis but in the absence of a universally accepted definition, contamination with aetiologically distinct conditions expressing a similar phenotype will remain an issue. Automated, objective quantification of trabeculation will help to define the normal distribution using big data without the constraint of wide interobserver variation.

The Role of Cardiovascular Magnetic Resonance in Sports Cardiology; Current Utility and Future Perspectives

Purpose of review

Cardiovascular magnetic resonance (CMR) is frequently used in the investigation of suspected cardiac disease in athletes. In this review, we discuss how CMR can be used in athletes with suspected cardiomyopathy with particular reference to volumetric analysis and tissue characterization. We also discuss the finding of non-ischaemic fibrosis in athletes describing its prevalence, distribution and clinical importance.

Recent findings

The strengths of CMR include high spatial resolution, unrestricted imaging planes and lack of ionizing radiation. Regular physical exercise leads to cardiac remodeling that in certain situations can be clinically challenging to differentiate from various cardiomyopathies. Thorough morphological assessment by CMR is fundamental to ensuring accurate diagnosis. Developments in tissue characterization by late gadolinium enhancement and T1 mapping have the potential to be powerful additional tools in this challenging clinical situation. Using late gadolinium enhancement, it is also possible to detect non-ischaemic fibrosis in athletes who do not have overt cardiomyopathy. The mechanisms of this fibrosis are unclear; however, it does appear to be clinically important. We also review data on the prevalence of non-ischaemic fibrosis in athletes.

Summary

CMR is a powerful tool to aid in the diagnosis of cardiomyopathy in athletes. It may also have a future role in assessing fibrosis related to long-term participation in sport.

Speckle Tracking Echocardiography for the Assessment of the Athlete's Heart: Is It Ready for Daily Practice?

PURPOSE OF REVIEW

To describe the use of speckle tracking echocardiography (STE) in the biventricular assessment of athletes' heart (AH). Can STE aid differential diagnosis during pre-participation cardiac screening (PCS) of athletes?

RECENT FINDINGS

Data from recent patient, population and athlete studies suggest potential discriminatory value of STE, alongside standard echocardiographic measurements, in the early detection of clinically relevant systolic dysfunction. STE can also contribute to subsequent prognosis and risk stratification. Despite some heterogeneity in STE data in athletes, left ventricular global longitudinal strain (GLS) and right ventricular longitudinal strain (RV ɛ) indices can add to differential diagnostic protocols in PCS. STE should be used in addition to standard echocardiographic tools and be conducted by an experienced operator with significant knowledge of the AH. Other indices, including left ventricular circumferential strain and twist, may provide insight, but further research in clinical and athletic populations is warranted. This review also raises the potential role for STE measures performed during exercise as well as in serial follow-up as a method to improve diagnostic yield.

Exercise cardiac MRI unmasks right ventricular dysfunction in acute hypoxia and chronic pulmonary arterial hypertension

Coupling of right ventricular (RV) contractility to afterload is maintained at rest in the early stages of pulmonary arterial hypertension (PAH), but exercise may unmask depleted contractile reserves. We assessed whether elevated afterload reduces RV contractile reserve despite compensated resting function using noninvasive exercise imaging. Fourteen patients with PAH (mean age: 39.1 yr, 10 women and 4 men) and 34 healthy control subjects (mean ageL 35.6 yr, 17 women and 17 men) completed real-time cardiac magnetic resonance imaging during submaximal exercise breathing room air. Control subjects were then also exercised during acute normobaric hypoxia (fraction of inspired O₂: 12%). RV contractile reserve was assessed by the effect of exercise on ejection fraction. In control subjects, the increase in RV ejection fraction on exercise was less during hypoxia (P = 0.017), but the response of left ventricular ejection fraction to exercise did not change. Patients with PAH had an impaired RV reserve, with half demonstrating a fall in RV ejection fraction on exercise despite comparable resting function to controls (PAH: rest 53.6 ± 4.3% vs. exercise 51.4 ± 10.7%; controls: rest 57.1 ± 5.2% vs. exercise 69.6 ± 6.1%, P < 0.0001). In control subjects, the increase in stroke volume index on exercise was driven by reduced RV end-systolic volume, whereas patients with PAH did not augment the stroke volume index, with increases in both end-diastolic and end-systolic volumes. From baseline hemodynamic and exercise capacity variables, only the minute ventilation-to-CO₂ output ratio was an independent predictor of RV functional reserve (P = 0.021). In conclusion, noninvasive cardiac imaging during exercise unmasks depleted RV contractile reserves in healthy adults under hypoxic conditions and patients with PAH under normoxic conditions despite preserved ejection fraction at rest.

NEW & NOTEWORTHY Right ventricular (RV) reserve was assessed using real-time cardiac magnetic resonance imaging in patients with pulmonary arterial hypertension and in healthy control subjects under normobaric hypoxia, which has been previously associated with acute pulmonary hypertension. Hypoxia caused a mild reduction in RV reserve, whereas chronic pulmonary arterial hypertension was associated with a marked reduction in RV reserve.

Differentiating Athlete's Heart From Cardiomyopathies - The Left Side

In athletes who undertake a high volume of high intensity exercise, the resultant changes in cardiac structure and function which develop as a result of physiological adaptation to exercise (so called "Athlete's Heart") may overlap with some features of pathological conditions. This chapter will focus on the left side of the heart, where left ventricular cavity enlargement, increase in left ventricular wall thickness and increased left ventricular trabeculation associated with athletic remodelling may sometimes be difficult to differentiate from conditions such as dilated cardiomyopathy, hypertrophic cardiomyopathy or isolated left ventricular non-compaction. The distinction between physiological versus pathological changes in athletes is imperative as an incorrect diagnosis can have important consequences, such as exclusion from competitive sport, or false reassurance and missed opportunity for effective therapeutic intervention.