Prevalence and pattern of cardiovascular magnetic resonance late gadolinium enhancement in highly trained endurance athletes

Imaging Features of Arrhythmogenic Cardiomyopathies

Arrhythmogenic cardiomyopathy (ACM) is a genetic disease characterized by replacement of ventricular myocardium with fibrofatty tissue, predisposing the patient to ventricular arrhythmias and/or sudden cardiac death. Most cases of ACM are associated with pathogenic variants in genes that encode desmosomal proteins, an important cell-to-cell adhesion complex present in both the heart and skin tissue. Although ACM was first described as a disease predominantly of the right ventricle, it is now acknowledged that it can also primarily involve the left ventricle or both ventricles. The original right-dominant phenotype is traditionally diagnosed using the 2010 task force criteria, a multifactorial algorithm divided into major and minor criteria consisting of structural criteria based on two-dimensional echocardiographic, cardiac MRI, or right ventricular angiographic findings; tissue characterization based on endomyocardial biopsy results; repolarization and depolarization abnormalities based on electrocardiographic findings; arrhythmic features; and family history. Shortfalls in the task force criteria due to the modern understanding of the disease have led to development of the Padua criteria, which include updated criteria for diagnosis of the right-dominant phenotype and new criteria for diagnosis of the left-predominant and biventricular phenotypes. In addition to incorporating cardiac MRI findings of ventricular dilatation, systolic dysfunction, and regional wall motion abnormalities, the new Padua criteria emphasize late gadolinium enhancement at cardiac MRI as a key feature in diagnosis and imaging-based tissue characterization. Conditions to consider in the differential diagnosis of the right-dominant phenotype include various other causes of right ventricular dilatation such as left-to-right shunts and variants of normal right ventricular anatomy that can be misinterpreted as abnormalities. The left-dominant phenotype can mimic myocarditis at imaging and clinical examination. Additional considerations for the differential diagnosis of ACM, particularly for the left-dominant phenotype, include sarcoidosis and dilated cardiomyopathy. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

No adverse association between exercise exposure and diffuse myocardial fibrosis in male endurance athletes

The potential association between endurance exercise and myocardial fibrosis is controversial. Data on exercise exposure and diffuse myocardial fibrosis in endurance athletes are scarce and conflicting. We aimed to investigate the association between exercise exposure and markers of diffuse myocardial fibrosis by cardiovascular magnetic resonance imaging (CMR) in endurance athletes. We examined 27 healthy adult male competitive endurance athletes aged 41 ± 9 years and 16 healthy controls in a cross sectional study using 3 Tesla CMR including late gadolinium enhancement and T1 mapping. Athletes reported detailed exercise history from 12 years of age. Left ventricular total mass, cellular mass and extracellular mass were higher in athletes than controls (86 vs. 58 g/m2, 67 vs. 44 g/m2 and 19 vs. 13 g/m2, all p < 0.01). Extracellular volume (ECV) was lower (21.5% vs. 23.8%, p = 0.03) and native T1 time was shorter (1214 ms vs. 1268 ms, p < 0.01) in the athletes. Increasing exercise dose was independently associated with shorter native T1 time (regression coefficient - 24.1, p < 0.05), but expressed no association with ECV. Our results indicate that diffuse myocardial fibrosis has a low prevalence in healthy male endurance athletes and do not indicate an adverse dose-response relationship between exercise and diffuse myocardial fibrosis in healthy athletes.

Multiparametric Cardiovascular Magnetic Resonance in Nonhospitalized COVID-19 Infection Subjects: An Intraindividual Comparison Study

PURPOSE

To investigate intraindividual cardiac structural and functional changes before and after COVID-19 infection in a previously healthy population with a 3T cardiac magnetic resonance (CMR).

MATERIALS AND METHODS

A total of 39 unhospitalized patients with COVID-19 were recruited. They participated in our previous study as non-COVID-19 healthy volunteers undergoing baseline CMR examination and were recruited to perform a repeated CMR examination after confirmed COVID-19 infection in December 2022. The CMR parameters were measured and compared between before and after COVID-19 infection with paired t tests. The laboratory measures including myocardial enzymes and inflammatory indicators were also collected when performing repeated CMR.

RESULTS

The median duration was 393 days from the first to second CMR and 26 days from clinical symptoms onset to the second CMR. Four patients (10.3%, 4/39) had the same late gadolinium enhancement pattern at baseline and repeated CMR and 5 female patients (12.8%, 5/39) had myocardial T2 ratio >2 (2.07 to 2.27) but with normal T2 value in post-COVID-19 CMR. All other CMR parameters were in normal ranges before and after COVID-19 infection. Between before and after the COVID-19 infection, there were no significant differences in cardiac structure, function, and tissue characterization, no matter with or without symptoms (fatigue, chest discomfort, palpitations, shortness of breath, and insomnia/sleep disorders) (all P >0.05). The laboratory measures at repeated CMR were in normal ranges in all participants.

CONCLUSIONS

These intraindividual CMR studies showed unhospitalized patients with COVID-19 with normal myocardial enzymes had no measurable CMR abnormalities, which can help alleviate wide social concerns about COVID-19-related myocarditis.

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.

Physical activity and the heart: from well-established cardiovascular benefits to possible adverse effects

The favorable effects of physical activity on the cardiovascular system have been well described in scientific literature. Physical activity reduces cardiovascular morbidity and mortality in both healthy subjects and in patients with cardiovascular disease. However, different intensity levels of physical activity have a different impact on the cardiovascular system. Some data support the hypothesis of a "physical activity paradox": repetitive exposure to vigorous physical activity may induce biological effects that counteract the benefits of moderate intensity levels of physical activity. In this review, we report the main effects of acute and chronic physical activity on the cardiovascular system and we summarize the biochemical mechanisms that may explain these effects.

Risk stratification in patients with structurally normal hearts: Does fibrosis type matter?

OBJECTIVES

The study sought to assess the prognostic significance of nonischemic myocardial fibrosis (MF) on cardiovascular magnetic resonance (CMR)-both macroscopic MF assessed by late gadolinium enhancement (LGE) and diffuse microscopic MF quantified by extracellular volume fraction (ECV)-in patients with structurally normal hearts.

BACKGROUND

The clinical relevance of tissue abnormalities identified by CMR in patients with structurally normal hearts remains unclear.

METHODS

Consecutive patients undergoing CMR were screened for inclusion to identify those with LGE imaging and structurally normal hearts. ECV was calculated in patients with available T1 mapping. The associations between myocardial fibrosis and the outcomes of all-cause mortality, new-onset heart failure [HF], and an arrhythmic outcome were evaluated.

RESULTS

In total 525 patients (mean age 43.1±14.2 years; 30.5% males) were included. Over a median follow-up of 5.8 years, 13 (2.5%) patients died and 18 (3.4%) developed new-onset HF. Nonischemic midwall /subepicardial LGE was present in 278 (52.9%) patients; isolated RV insertion fibrosis was present in 80 (15.2%) patients. In 276 patients with available T1 mapping, the mean ECV was 25.5 ± 4.4%. There was no significant association between LGE and all-cause mortality (HR: 1.36, CI: 0.42-4.42, p = 0.61), or new-onset HF (HR: 0.64, CI: 0.25-1.61, p = 0.34). ECV (per 1% increase) correlated with all-cause mortality (HR: 1.19, CI: 1.04-1.36, p = 0.009), but not with new-onset HF (HR: 0.97, CI: 0.86-1.10, p = 0.66). There was no significant association between arrhythmic outcomes and LGE (p = 0.60) or ECV (p = 0.49). In a multivariable model after adjusting for covariates, ECV remained significantly associated with all-cause mortality (HR per 1% increase in ECV: 1.26, CI: 1.06-1.50, p = 0.009).

CONCLUSION

Nonischemic LGE in patients with structurally normal hearts is common and does not appear to be associated with adverse outcomes, whereas elevated ECV is associated with all-cause mortality and may be an important risk stratification tool.

Cardiac structure discontinuities revealed by ex-vivo microstructural characterization. A focus on the basal inferoseptal left ventricle region

BACKGROUND

While the microstructure of the left ventricle (LV) has been largely described, only a few studies investigated the right ventricular insertion point (RVIP). It was accepted that the aggregate cardiomyocytes organization was much more complex due to the intersection of the ventricular cavities but a precise structural characterization in the human heart was lacking even if clinical phenotypes related to right ventricular wall stress or arrhythmia were observed in this region.

METHODS

MRI-derived anatomical imaging (150 µm3) and diffusion tensor imaging (600 µm3) were performed in large mammalian whole hearts (human: N = 5, sheep: N = 5). Fractional anisotropy, aggregate cardiomyocytes orientations and tractography were compared within both species. Aggregate cardiomyocytes orientation on one ex-vivo sheep whole heart was then computed using structure tensor imaging (STI) from 21 µm isotropic acquisition acquired with micro computed tomography (MicroCT) imaging. Macroscopic and histological examination were performed. Lastly, experimental cardiomyocytes orientation distribution was then compared to the usual rule-based model using electrophysiological (EP) modeling. Electrical activity was modeled with the monodomain formulation.

RESULTS

The RVIP at the level of the inferior ventricular septum presented a unique arrangement of aggregate cardiomyocytes. An abrupt, mid-myocardial change in cardiomyocytes orientation was observed, delimiting a triangle-shaped region, present in both sheep and human hearts. FA's histogram distribution (mean ± std: 0.29 ± 0.06) of the identified region as well as the main dimension (22.2 mm ± 5.6 mm) was found homogeneous across samples and species. Averaged volume is 0.34 cm3 ± 0.15 cm3. Both local activation time (LAT) and morphology of pseudo-ECGs were strongly impacted with delayed LAT and change in peak-to-peak amplitude in the simulated wedge model.

CONCLUSION

The study was the first to describe the 3D cardiomyocytes architecture of the basal inferoseptal left ventricle region in human hearts and identify the presence of a well-organized aggregate cardiomyocytes arrangement and cardiac structural discontinuities. The results might offer a better appreciation of clinical phenotypes like RVIP-late gadolinium enhancement or uncommon idiopathic ventricular arrhythmias (VA) originating from this region.

Cardiac imaging in athlete's heart: current status and future prospects

BACKGROUND

Physical activity contributes to changes in cardiac morphology, which are known as "athlete's heart". Therefore, these modifications can be characterized using different imaging modalities such as echocardiography, including Doppler (flow Doppler and Doppler myocardial imaging) and speckle-tracking, along with cardiac magnetic resonance, and cardiac computed tomography.

MAIN TEXT

Echocardiography is the most common method for assessing cardiac structure and function in athletes due to its availability, repeatability, versatility, and low cost. It allows the measurement of parameters like left ventricular wall thickness, cavity dimensions, and mass. Left ventricular myocardial strain can be measured by tissue Doppler (using the pulse wave Doppler principle) or speckle tracking echocardiography (using the two-dimensional grayscale B-mode images), which provide information on the deformation of the myocardium. Cardiac magnetic resonance provides a comprehensive evaluation of cardiac morphology and function with superior accuracy compared to echocardiography. With the addition of contrast agents, myocardial state can be characterized. Thus, it is particularly effective in differentiating an athlete's heart from pathological conditions, however, is less accessible and more expensive compared to other techniques. Coronary computed tomography is used to assess coronary artery anatomy and identify anomalies or diseases, but its use is limited due to radiation exposure and cost, making it less suitable for young athletes. A novel approach, hemodynamic forces analysis, uses feature tracking to quantify intraventricular pressure gradients responsible for blood flow. Hemodynamic forces analysis has the potential for studying blood flow within the heart and assessing cardiac function.

CONCLUSIONS

In conclusion, each diagnostic technique has its own advantages and limitations for assessing cardiac adaptations in athletes. Examining and comparing the cardiac adaptations resulting from physical activity with the structural cardiac changes identified through different diagnostic modalities is a pivotal focus in the field of sports medicine.

Long-term cardiotoxicity in germ cell cancer survivors after platinum-based chemotherapy: cardiac MR shows impaired systolic function and tissue alterations

OBJECTIVES

Long-term toxicities of germ cell cancer (GCC) treatment are of particular importance in young men with a life expectancy of several decades after curative treatment. This study aimed to investigate the long-term effects of platinum-based chemotherapy on cardiac function and myocardial tissue in GCC survivors by cardiac magnetic resonance (CMR) imaging.

METHODS

Asymptomatic GCC survivors ≥ 3 years after platinum-based chemotherapy and age-matched healthy controls underwent CMR assessment, including left ventricular (LV) and right ventricular (RV) ejection fraction (EF), strain analysis, late gadolinium enhancement (LGE) imaging, and T1/T2 mapping.

RESULTS

Forty-four survivors (age 44 [interquartile range, IQR 37-52] years; follow-up time 10 [IQR 5-15] years after chemotherapy) and 21 controls were evaluated. LV- and RVEF were lower in GCC survivors compared to controls (LVEF 56 ± 5% vs. 59 ± 5%, p = 0.017; RVEF 50 ± 7% vs. 55 ± 7%, p = 0.008). Seven percent (3/44) of survivors showed reduced LVEF (< 50%), and 41% (18/44) showed borderline LVEF (50-54%). The strain analysis revealed significantly reduced deformation compared to controls (LV global longitudinal strain [GLS] -13 ± 2% vs. -15 ± 1%, p < 0.001; RV GLS -15 ± 4% vs. -19 ± 4%, p = 0.005). Tissue characterization revealed focal myocardial fibrosis in 9 survivors (20%) and lower myocardial native T1 times in survivors compared to controls (1202 ± 25 ms vs. 1226 ± 37 ms, p = 0.016). Attenuated LVEF was observed after two cycles of platinum-based chemotherapy (54 ± 5% vs. 62 ± 5%, p < 0.001).

CONCLUSION

Based on CMR evaluation, combination chemotherapy with cumulative cisplatin ≥ 200 mg/m2 is associated with attenuated biventricular systolic function and myocardial tissue alterations in asymptomatic long-term GCC survivors.

CLINICAL RELEVANCE STATEMENT

Platinum-based chemotherapy is associated with decreased systolic function, non-ischemic focal myocardial scar, and decreased T1 times in asymptomatic long-term germ cell cancer survivors. Clinicians should be particularly aware of the risk of cardiac toxicity after platinum-based chemotherapy.

KEY POINTS

• Platinum-based chemotherapy is associated with attenuation of biventricular systolic function, lower myocardial T1 relaxation times, and non-ischemic late gadolinium enhancement. • Decreased systolic function and non-ischemic late gadolinium enhancement are associated with a cumulative cisplatin dose of  ≥ 200 mg/m2. • Cardiac MRI can help to identify chemotherapy-associated changes in cardiac function and tissue in asymptomatic long-term germ cell cancer survivors.

Identification of non-ischaemic fibrosis in male veteran endurance athletes, mechanisms and association with premature ventricular beats

Left ventricular fibrosis can be identified by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in some veteran athletes. We aimed to investigate prevalence of ventricular fibrosis in veteran athletes and associations with cardiac arrhythmia. 50 asymptomatic male endurance athletes were recruited. They underwent CMR imaging including volumetric analysis, bright blood (BB) and dark blood (DB) LGE, motion corrected (MOCO) quantitative stress and rest perfusion and T1/T2/extracellular volume mapping. Athletes underwent 12-lead electrocardiogram (ECG) and 24-h ECG. Myocardial fibrosis was identified in 24/50 (48%) athletes. All fibrosis was mid-myocardial in the basal-lateral left ventricular wall. Blood pressure was reduced in athletes without fibrosis compared to controls, but not athletes with fibrosis. Fibrotic areas had longer T2 time (44 ± 4 vs. 40 ± 2 ms, p < 0.0001) and lower rest myocardial blood flow (MBF, 0.5 ± 0.1 vs. 0.6 ± 0.1 ml/g/min, p < 0.0001). On 24-h ECG, athletes with fibrosis had greater burden of premature ventricular beats (0.3 ± 0.6 vs. 0.05 ± 0.2%, p = 0.03), with higher prevalence of ventricular couplets and triplets (33 vs. 8%, p = 0.02). In veteran endurance athletes, myocardial fibrosis is common and associated with an increased burden of ventricular ectopy. Possible mechanisms include inflammation and blood pressure. Further studies are needed to establish whether fibrosis increases risk of malignant arrhythmic events.

Investigation of Unexplained Cardiac Arrest: Phenotyping and Genetic Testing

Unexplained cardiac arrest (UCA) is a working diagnosis that should be replaced by a final diagnosis once evaluation is completed. Complete evaluation of UCA should include high-yield tests like cardiac magnetic resonance imaging, exercise treadmill test, and sodium-channel blocker challenge to identify latent causes of UCA. If no clear etiology is revealed after complete evaluation, idiopathic ventricular fibrillation may be diagnosed, and the strength of its diagnosis can be divided into definitive, probable, and possible based on the number of high-yield tests performed. Care should be provided by a multidisciplinary team with expertise in this area.

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.

Multimodality Cardiac Imaging in COVID

Infection with SARS-CoV-2, the virus that causes COVID, is associated with numerous potential secondary complications. Global efforts have been dedicated to understanding the myriad potential cardiovascular sequelae which may occur during acute infection, convalescence, or recovery. Because patients often present with nonspecific symptoms and laboratory findings, cardiac imaging has emerged as an important tool for the discrimination of pulmonary and cardiovascular complications of this disease. The clinician investigating a potential COVID-related complication must account not only for the relative utility of various cardiac imaging modalities but also for the risk of infectious exposure to staff and other patients. Extraordinary clinical and scholarly efforts have brought the international medical community closer to a consensus on the appropriate indications for diagnostic cardiac imaging during this protracted pandemic. In this review, we summarize the existing literature and reference major societal guidelines to provide an overview of the indications and utility of echocardiography, nuclear imaging, cardiac computed tomography, and cardiac magnetic resonance imaging for the diagnosis of cardiovascular complications of COVID.

Minor Myocardial Scars in Association with Cardiopulmonary Function after COVID-19

BACKGROUND

Myocardial scars detected by cardiovascular magnetic resonance (CMR) imaging after COVID-19 have caused concerns regarding potential long-term cardiovascular consequences.

OBJECTIVE

The objective of this study was to investigate cardiopulmonary functioning in patients with versus without COVID-19-related myocardial scars.

METHODS

In this prospective cohort study, CMR was performed approximately 6 months after moderate-to-severe COVID-19. Before (∼3 months post-COVID-19) and after (∼12 months post-COVID-19) the CMR, patients underwent extensive cardiopulmonary testing with cardiopulmonary exercise tests, 24-h ECG, and echocardiography. We excluded participants with overt heart failure.

RESULTS

Post-COVID-19 CMR was available in 49 patients with cardiopulmonary tests at 3 and 12 months after the index hospitalization. Nine (18%) patients had small late gadolinium enhancement-detected myocardial scars. Patients with myocardial scars were older (63.2 ± 13.2 vs. 56.2 ± 13.2 years) and more frequently men (89% vs. 55%) compared to those without scars. Cardiorespiratory fitness was similar in patients with and without scars, i.e., peak oxygen uptake: 82.1 ± 11.5% versus 76.3 ± 22.5% of predicted, respectively (p = 0.46). The prevalence of ventricular premature contractions and arrhythmias was low and not different by the presence of myocardial scar. Cardiac structure and function assessed by echocardiography were similar between the groups, except for a tendency of greater left ventricular mass in those with scars (75 ± 20 vs. 62 ± 14, p = 0.02 and p = 0.08 after adjusting for age and sex). There were no significant associations between myocardial scar and longitudinal changes in cardiopulmonary function from 3 to 12 months.

CONCLUSION

Our findings imply that the presence of minor myocardial scars has limited clinical significance with respect to cardiopulmonary function after COVID-19.

Cardiac electrophysiological remodeling associated with enhanced arrhythmia susceptibility in a canine model of elite exercise

The health benefits of regular physical exercise are well known. Even so, there is increasing evidence that the exercise regimes of elite athletes can evoke cardiac arrhythmias including ventricular fibrillation and even sudden cardiac death (SCD). The mechanism of exercise-induced arrhythmia and SCD is poorly understood. Here, we show that chronic training in a canine model (12 sedentary and 12 trained dogs) that mimics the regime of elite athletes induces electrophysiological remodeling (measured by ECG, patch-clamp, and immunocytochemical techniques) resulting in increases of both the trigger and the substrate for ventricular arrhythmias. Thus, 4 months sustained training lengthened ventricular repolarization (QTc: 237.1±3.4 ms vs. 213.6±2.8 ms, n=12; APD90: 472.8±29.6 ms vs. 370.1±32.7 ms, n=29 vs. 25), decreased transient outward potassium current (6.4±0.5 pA/pF vs. 8.8±0.9 pA/pF at 50 mV, n=54 vs. 42), and increased the short-term variability of repolarization (29.5±3.8 ms vs. 17.5±4.0 ms, n=27 vs. 18). Left ventricular fibrosis and HCN4 protein expression were also enhanced. These changes were associated with enhanced ectopic activity (number of escape beats from 0/hr to 29.7±20.3/hr) in vivo and arrhythmia susceptibility (elicited ventricular fibrillation: 3 of 10 sedentary dogs vs. 6 of 10 trained dogs). Our findings provide in vivo, cellular electrophysiological and molecular biological evidence for the enhanced susceptibility to ventricular arrhythmia in an experimental large animal model of endurance training.

Prognostic impact of late gadolinium enhancement at the right ventricular insertion points in non-ischaemic dilated cardiomyopathy

AIMS

To evaluate the baseline characteristics and the prognostic implications associated with late gadolinium enhancement limited to the right ventricular insertion points (IP-LGE) or present at both the right ventricular insertion points and the left ventricle (IP&LV-LGE) in non-ischaemic dilated cardiomyopathy (DCM).

METHODS AND RESULTS

This is a retrospective observational multicentre cohort study including 1165 consecutive patients with DCM evaluated by cardiac magnetic resonance. The primary endpoint included appropriate defibrillator therapies, sustained ventricular tachycardia, resuscitated cardiac arrest, or sudden death. The secondary outcome encompassed heart failure hospitalizations, heart transplant, left ventricular assist device implantation, and end-stage heart failure death. IP-LGE was found in 72 patients (6%), who had clinical characteristics closer to LGE- than to LGE+ patients. During follow-up (median 36 months), none of the IP-LGE patients experienced the primary endpoint. The cumulative incidence of the primary endpoint was similar between IP-LGE and LGE- patients (P = 1), while IP-LGE had significantly lower cumulative incidence when compared with LGE+ patients (P < 0.001). When compared with IP-LGE patients, the cumulative incidence of the secondary endpoint was similar in LGE- cases (P = 0.86) but tended to be higher in LGE+ patients (P = 0.06). Both clinical characteristics and outcomes were similar between IP&LV-LGE patients and the rest of LGE+ cases.

CONCLUSIONS

In a large cohort of DCM patients, IP-LGE was associated with similar outcome when compared with LGE- patients and with significant lower risk of ventricular arrhythmias and sudden death when compared with LGE+ cases. Patients with IP&LV-LGE had clinical characteristics and outcomes similar to the rest of LGE+ cases.

Approach to optimal assessment of right ventricular remodelling in heart transplant recipients: insights from myocardial work index, T1 mapping, and endomyocardial biopsy

AIMS

Right ventricular (RV) dysfunction is an important cause of graft failure after heart transplantation (HTx). We sought to investigate relative merits of echocardiographic tools and cardiac magnetic resonance (CMR) with T1 mapping for the assessment of functional adaptation and remodelling of the RV in HTx recipients.

METHODS AND RESULTS

Sixty-one complete data set of echocardiography, CMR, right heart catheterization, and biopsy were obtained. Myocardial work index (MWI) was quantified by integrating longitudinal strain (LS) with invasively measured pulmonary artery pressure. CMR derived RV volumes, T1 time, and extracellular volume (ECV) were quantified. Endomyocardial biopsy findings were used as the reference standard for myocardial microstructural changes. In HTx recipients who never had a previous allograft rejection, longitudinal function parameters were lower than healthy organ donors, while ejection fraction (EF) (52.0 ± 8.7%) and MWI (403.2 ± 77.2 mmHg%) were preserved. Rejection was characterized by significantly reduced LS, MWI, longer T1 time, and increased ECV that improved after recovery, whereas RV volumes and EF did not change MWI was the strongest determinant of rejection related myocardial damage (area under curve: 0.812, P < 0.0001, 95% CI: 0.69-0.94) with good specificity (77%), albeit modest sensitivity. In contrast, T1 time and ECV were sensitive (84%, both) but not specific to detect subclinical RV damage.

CONCLUSION

Subclinical adaptive RV remodelling is characterized by preserved RV EF despite longitudinal function abnormalities, except for MWI. While ultrastructural damage is reflected by MWI, ECV, and T1 time, only MWI has the capability to discriminate functional adaptation from transition to subclinical structural damage.

Impact of COVID-19 on Cardiovascular Disease

Coronavirus disease 2019 (COVID-19) is a viral infection with the novel severe acute respiratory distress syndrome corona virus 2 (SARS-CoV-2). Until now, more than 670 million people have suffered from COVID-19 worldwide, and roughly 7 million death cases were attributed to COVID-19. Recent evidence suggests an interplay between COVID-19 and cardiovascular disease (CVD). COVID-19 may serve as a yet underappreciated CVD risk modifier, including risk factors such as diabetes mellitus or arterial hypertension. In addition, recent data suggest that previous COVID-19 may increase the risk for many entities of CVD to an extent similarly observed for traditional cardiovascular (CV) risk factors. Furthermore, increased CVD incidence and worse clinical outcomes in individuals with preexisting CVD have been observed for myocarditis, acute coronary syndrome, heart failure (HF), thromboembolic complications, and arrhythmias. Direct and indirect mechanisms have been proposed by which COVID-19 may impact CVD and CV risk, including viral entry into CV tissue or by the induction of a massive systemic inflammatory response. In the current review, we provide an overview of the literature reporting an interaction between COVID-19 and CVD, review potential mechanisms underlying this interaction, and discuss preventive and treatment strategies and their interference with CVD that were evaluated since the onset of the COVID-19 pandemic.

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.

Utilization of Cardiovascular Magnetic Resonance Imaging for Resumption of Athletic Activities Following COVID-19 Infection: An Expert Consensus Document on Behalf of the American Heart Association Council on Cardiovascular Radiology and Intervention Leadership and Endorsed by the Society for Cardiovascular Magnetic Resonance

The global pandemic of COVID-19 caused by infection with SARS-CoV-2 is now entering its fourth year with little evidence of abatement. As of December 2022, the World Health Organization Coronavirus (COVID-19) Dashboard reported 643 million cumulative confirmed cases of COVID-19 worldwide and 98 million in the United States alone as the country with the highest number of cases. Although pneumonia with lung injury has been the manifestation of COVID-19 principally responsible for morbidity and mortality, myocardial inflammation and systolic dysfunction though uncommon are well-recognized features that also associate with adverse prognosis. Given the broad swath of the population infected with COVID-19, the large number of affected professional, collegiate, and amateur athletes raises concern regarding the safe resumption of athletic activity (return to play) following resolution of infection. A variety of different testing combinations that leverage ECG, echocardiography, circulating cardiac biomarkers, and cardiovascular magnetic resonance imaging have been proposed and implemented to mitigate risk. Cardiovascular magnetic resonance in particular affords high sensitivity for myocarditis but has been employed and interpreted nonuniformly in the context of COVID-19 thereby raising uncertainty as to the generalizability and clinical relevance of findings with respect to return to play. This consensus document synthesizes available evidence to contextualize the appropriate utilization of cardiovascular magnetic resonance in the return to play assessment of athletes with prior COVID-19 infection to facilitate informed, evidence-based decisions, while identifying knowledge gaps that merit further investigation.

COVID-19 and elite sport: Cardiovascular implications and return-to-play

Curtailing elite sports during the coronavirus disease 2019 (COVID-19) pandemic was necessary to prevent widespread viral transmission. Now that elite sport and international competitions have been largely restored, there is still a need to devise appropriate screening and management pathways for athletes with a history of, or current, COVID-19 infection. These approaches should support the decision-making process of coaches, sports medicine practitioners and the athlete about the suitability to return to training and competition activities. In the absence of longitudinal data sets from athlete populations, the incidence of developing prolonged and debilitating symptoms (i.e., Long COVID) that affects a return to training and competition remains a challenge to sports and exercise scientists, sports medicine practitioners and clinical groups. As the world attempts to adjust toward 'living with COVID-19' the very nature of elite and international sporting competition poses a risk to athlete welfare that must be screened for and managed with bespoke protocols that consider the cardiovascular implications for performance.

Utilization of cardiovascular magnetic resonance (CMR) imaging for resumption of athletic activities following COVID-19 infection: an expert consensus document on behalf of the American Heart Association Council on Cardiovascular Radiology and Intervention (CVRI) Leadership and endorsed by the Society for Cardiovascular Magnetic Resonance (SCMR)

The global pandemic of coronavirus disease 2019 (COVID-19) caused by infection with severe acute respiratory suyndrome coronavirus 2 (SARS-CoV-2) is now entering its 4th year with little evidence of abatement. As of December 2022, the World Health Organization Coronavirus (COVID-19) Dashboard reported 643 million cumulative confirmed cases of COVID-19 worldwide and 98 million in the United States alone as the country with the highest number of cases. While pneumonia with lung injury has been the manifestation of COVID-19 principally responsible for morbidity and mortality, myocardial inflammation and systolic dysfunction though uncommon are well-recognized features that also associate with adverse prognosis. Given the broad swath of the population infected with COVID-19, the large number of affected professional, collegiate, and amateur athletes raises concern regarding the safe resumption of athletic activity (return to play, RTP) following resolution of infection. A variety of different testing combinations that leverage the electrocardiogram, echocardiography, circulating cardiac biomarkers, and cardiovascular magnetic resonance (CMR) imaging have been proposed and implemented to mitigate risk. CMR in particular affords high sensitivity for myocarditis but has been employed and interpreted non-uniformly in the context of COVID-19 thereby raising uncertainty as to the generalizability and clinical relevance of findings with respect to RTP. This consensus document synthesizes available evidence to contextualize the appropriate utilization of CMR in the RTP assessment of athletes with prior COVID-19 infection to facilitate informed, evidence-based decisions, while identifying knowledge gaps that merit further investigation.

Cardiac involvement in patients 1 year after recovery from moderate and severe COVID-19 infections

Background

Some patients suffered persistent cardiac symptoms after hospital discharge following COVID-19 infection, including chest tightness, chest pain, and palpitation. However, the cardiac involvement in these patients remains unknown. The purpose of this study was to investigate the effect of COVID-19 infection on the cardiovascular system after 1 year of recovery in patients hospitalized with persistent cardiac symptoms.

Materials and methods

In this prospective observational study, a total of 32 patients who had COVID-19 (11 diagnosed as severe COVID-19 and 21 as moderate) with persistent cardiac symptoms after hospital discharge were enrolled. Contrast-enhanced cardiovascular magnetic resonance (CMR) imaging was performed on all patients. Comparisons were made with age- and sex-matched healthy controls (n = 13), and age-, sex- and risk factor-matched controls (n = 21). Further analysis was made between the severe and moderate COVID-19 cohorts.

Results

The mean time interval between acute COVID-19 infection and CMR was 462 ± 18 days. Patients recovered from COVID-19 had reduced left ventricular ejection fraction (LVEF) (p = 0.003) and increased extracellular volumes (ECVs) (p = 0.023) compared with healthy controls. Focal late gadolinium enhancement (LGE) was found in 22 (68.8%) patients, mainly distributed linearly in the septal mid-wall or patchily in RV insertion point. The LGE extent in patients with severe COVID-19 was higher than that in patients with moderate COVID-19 (p = 0.009).

Conclusion

This 1-year follow-up study revealed that patients with persistent cardiac symptoms, after recovering from COVID-19, had decreased cardiac function and increased ECV compared with healthy controls. Patients with COVID-19 predominately had a LGE pattern of septal mid-wall or RV insertion point. Patients with severe COVID-19 had greater LGE extent than patients with moderate COVID-19.

Certainties and Uncertainties of Cardiac Magnetic Resonance Imaging in Athletes

Prolonged and intensive exercise induces remodeling of all four cardiac chambers, a physiological process which is coined as the “athlete’s heart”. This cardiac adaptation, however, shows overlapping features with non-ischemic cardiomyopathies, such as dilated, arrhythmogenic and hypertrophic cardiomyopathy, also associated with athlete’s sudden cardiac death. Cardiac magnetic resonance (CMR) is a well-suited, highly reproducible imaging modality that can help differentiate athlete’s heart from cardiomyopathy. CMR allows accurate characterization of the morphology and function of cardiac chambers, providing full coverage of the ventricles. Moreover, it permits an in-depth understanding of the myocardial changes through specific techniques such as mapping or late gadolinium enhancement. In this narrative review, we will focus on the certainties and uncertainties of the role of CMR in sports cardiology. The main aspects of physiological adaptation due to regular and intensive sports activity and the application of CMR in highly trained athletes will be summarized.

Reduced Circumferential Strain in Athletes with Prior COVID-19

Purpose

To characterize global and segmental circumferential systolic strain (CS) measured by cardiac MRI in athletes after SARS-CoV-2 infection.

Materials and Methods

This retrospective observational cohort study included 188 soldiers and collegiate athletes referred for cardiac MRI after SARS-CoV-2 infection (C19+) between July 2020 and February 2021 and a control group of 72 soldiers, collegiate, and high school athletes who underwent cardiac MRI from May 2019 to February 2020, prior to the first SARS-CoV-2 case detected in our region (C19-). Global and segmental CS were measured by feature tracking, then compared between each group using unadjusted and multivariable- adjusted models. Acute myocarditis was diagnosed according to the modified Lake Louise criteria and the location of pathologic late gadolinium enhancement (LGE) was ascertained.

Results

Among the 188 C19+ athletes (median age, 25 years [IQR, 23-30]; 131 men), the majority had mild illness. Global CS significantly differed between C19+ and C19- groups, with a median of -24.0 (IQR -25.8, -21.4) versus. -25.0 (-28.0, -22.4), respectively (p = .009). This difference in CS persisted following adjustment for age, sex, body mass index, heart rate, and systolic blood pressure β coefficient 1.29 [95% CI: 0.20, 2.38], p = .02). In segmental analysis, the basal- and mid- inferoseptal, septal and inferolateral segments were significantly different (p < .05), which had a higher frequency of post-COVID late gadolinium enhancement. The global and segmental differences were similar after exclusion of athletes with myocarditis.

Conclusion

Among athletes, SARS-CoV-2 infection was associated with a small but statistically significant reduced CS.

A groupwise registration and tractography framework for cardiac myofiber architecture description by diffusion MRI: An application to the ventricular junctions

Background

Knowledge of the normal myocardial–myocyte orientation could theoretically allow the definition of relevant quantitative biomarkers in clinical routine to diagnose heart pathologies. A whole heart diffusion tensor template representative of the global myofiber organization over species is therefore crucial for comparisons across populations. In this study, we developed a groupwise registration and tractography framework to resolve the global myofiber arrangement of large mammalian sheep hearts. To demonstrate the potential application of the proposed method, a novel description of sub-regions in the intraventricular septum is presented.

Methods

Three explanted sheep (ovine) hearts (size ~12×8×6 cm3, heart weight ~ 150 g) were perfused with contrast agent and fixative and imaged in a 9.4T magnet. A group-wise registration of high-resolution anatomical and diffusion-weighted images were performed to generate anatomical and diffusion tensor templates. Diffusion tensor metrics (eigenvalues, eigenvectors, fractional anisotropy …) were computed to provide a quantitative and spatially-resolved analysis of cardiac microstructure. Then tractography was performed using deterministic and probabilistic algorithms and used for different purposes: i) Visualization of myofiber architecture, ii) Segmentation of sub-area depicting the same fiber organization, iii) Seeding and Tract Editing. Finally, dissection was performed to confirm the existence of macroscopic structures identified in the diffusion tensor template.

Results

The template creation takes advantage of high-resolution anatomical and diffusion-weighted images obtained at an isotropic resolution of 150 μm and 600 μm respectively, covering ventricles and atria and providing information on the normal myocardial architecture. The diffusion metric distributions from the template were found close to the one of the individual samples validating the registration procedure. Small new sub-regions exhibiting spatially sharp variations in fiber orientation close to the junctions of the septum and ventricles were identified. Each substructure was defined and represented using streamlines. The existence of a fiber-bundles in the posterior junction was validated by anatomical dissection. A complex structural organization of the anterior junction in comparison to the posterior junction was evidenced by the high-resolution acquisition.

Conclusions

A new framework combining cardiac template generation and tractography was applied on the whole sheep heart. The framework can be used for anatomical investigation, characterization of microstructure and visualization of myofiber orientation across samples. Finally, a novel description of the ventricular junction in large mammalian sheep hearts was proposed.

Low Risk of Cardiac Complications in Collegiate Athletes After Asymptomatic or Mild COVID-19 Infection

OBJECTIVE

The objective of this study was to determine the utility of "standard" cardiac screening with EKG, echocardiography, and serum troponin T (hs-Tn T) testing after COVID infection in competitive college athletes.

DESIGN

Prospective cohort study.

SETTING

Tertiary cardiology clinic, university training room.

PARTICIPANTS

Sixty-five Division 1 athletes recovered from COVID-19 and 465 controls.

ASSESSMENT

All COVID-recovered athletes underwent cardiac screening on return to campus in fall 2020. Controls were screened if indicated by preparticipation examination. Students cleared for sports participation were followed for the development of cardiac complications.

MAIN OUTCOME MEASURE

Incidence of cardiac complications after COVID infection.

RESULTS

Infected athletes experienced mild (26/65), moderate (8/65), or no (31/65) COVID symptoms. No athletes had severe symptoms. Men were more likely to have been asymptomatic (20/31), and women were more likely to have had moderate (7/8) symptoms (P = 0.015). All athletes, except 2 with anosmia, were asymptomatic at the time of cardiac testing. One athlete had persistently elevated hs-Tn T but no evidence of myocarditis on cardiac MRI. All other cardiac testing was negative. No athletes were diagnosed with myocarditis (95% CI: 0%-5.5%). All athletes were cleared for athletic participation. None suffered complications over the next 9 months.

CONCLUSIONS

After COVID-19 infection, no college athletes with mild, moderate, or no symptoms had signs of myocarditis, and all returned to play without cardiac complication. These findings support consensus opinion recommendations that college-age athletes who recovered from COVID-19 and who experienced mild or no symptoms may return to play without cardiac testing.

Long-term cardiac surveillance and outcomes of COVID-19 patients

Acute cardiac manifestions of COVID-19 have been well described, while chronic cardiac sequelae remain less clear. Various studies have shown conflicting data on the prevalence of new or worsening cardiovascular disease, myocarditis or cardiac dysrhythmias among patients recovered from COVID-19. Data are emerging that show that patients recovering from COVID-19 have an increased incidence of myocarditis and arrhythmias after recovery from COVID-19 compared with the control groups without COVID-19. The incidence of myocarditis after COVID-19 infection is low but is still significantly greater than the incidence of myocarditis from a COVID-19 vaccine. There have been several studies of athletes who underwent a variety of screening protocols prior to being cleared to return to exercise and competition. The data show possible, probable or definite myocarditis or cardiac injury among 0.4–3.0% of the athletes studied. Recent consensus statements suggest that athletes with full recovery and absence of cardiopulmonary symptoms may return to exercise and competition without cardiovascular testing. In conclusion, patients with COVID-19 may be expected to have an increased risk of cardiovascular disease, myocarditis or arrhythmias during the convalescent phase. Fortunately, the majority of patients, including athletes may return to their normal activity after recovery from COVID 19, in the absence of persisting cardiovascular symptoms.

Diagnostic evaluation and cardiopulmonary exercise test findings in young athletes with persistent symptoms following COVID-19

OBJECTIVES

Persistent or late-onset cardiopulmonary symptoms following COVID-19 may occur in athletes despite a benign initial course. We examined the yield of cardiac evaluation, including cardiopulmonary exercise testing (CPET), in athletes with cardiopulmonary symptoms after COVID-19, compared CPETs in these athletes and those without COVID-19 and evaluated longitudinal changes in CPET with improvement in symptoms.

METHODS

This prospective cohort study evaluated young (18-35 years old) athletes referred for cardiopulmonary symptoms that were present>28 days from COVID-19 diagnosis. CPET findings in post-COVID athletes were compared with a matched reference group of healthy athletes without COVID-19. Post-COVID athletes underwent repeat CPET between 3 and 6 months after initial evaluation.

RESULTS

Twenty-one consecutive post-COVID athletes with cardiopulmonary symptoms (21.9±3.9 years old, 43% female) were evaluated 3.0±2.1 months after diagnosis. No athlete had active inflammatory heart disease. CPET reproduced presenting symptoms in 86%. Compared with reference athletes (n=42), there was similar peak VO2 but a higher prevalence of abnormal spirometry (42%) and low breathing reserve (42%). Thirteen athletes (62%) completed longitudinal follow-up (4.8±1.9 months). The majority (69%) had reduction in cardiopulmonary symptoms, accompanied by improvement in peak VO2 and oxygen pulse, and reduction in resting and peak heart rate (all p<0.05).

CONCLUSION

Despite a high burden of cardiopulmonary symptoms after COVID-19, no athlete had active inflammatory heart disease. CPET was clinically useful to reproduce symptoms with either normal testing or identification of abnormal spirometry as a potential therapeutic target. Improvement in post-COVID symptoms was accompanied by improvements in CPET parameters.

Role of cardiac magnetic resonance imaging in troponinemia syndromes

Cardiac magnetic resonance imaging (MRI) is an evolving technology, proving to be a highly accurate tool for quantitative assessment. Most recently, it has been increasingly used in the diagnostic and prognostic evaluation of conditions involving an elevation in troponin or troponinemia. Although an elevation in troponin is a nonspecific marker of myocardial tissue damage, it is a frequently ordered investigation leaving many patients without a specific diagnosis. Fortunately, the advent of newer cardiac MRI protocols can provide additional information. In this review, we discuss several conditions associated with an elevation in troponin such as myocardial infarction, myocarditis, Takotsubo cardiomyopathy, coronavirus disease 2019 related cardiac dysfunction and athlete’s heart syndrome.

Myocarditis in Athletes Recovering from COVID-19: A Systematic Review and Meta-Analysis

Background: To assess the event rates of myocarditis detected by Cardiac Magnetic Resonance (CMR) in athletes who recovered from COVID-19. Methods: A systematic literature search was performed to identify studies reporting abnormal CMR findings in athletes who recovered from COVID-19. Secondary analyses were performed considering increased serum high sensitivity troponin (hs-Tn) levels and electrocardiographic (ECG) and echocardiographic (ECHO) abnormalities. Results: In total, 7988 athletes from 15 studies were included in the analysis. The pooled event rate of myocarditis was 1% (CI 1–2%), reaching 4% in the sub-group analysis. In addition, heterogeneity was observed (I2 43.8%). The pooled event rates of elevated serum hs-Tn levels, abnormal ECG and ECHO findings were 2% (CI 1–5%), 3% (CI 1–10%) and 2% (CI 1–6%), respectively. ECG, ECHO and serum hs-Tn level abnormalities did not show any correlation with myocarditis. Conclusions: The prevalence of COVID-19-related myocarditis in the athletic population ranges from 1 to 4%. Even if the event rate is quite low, current screening protocols are helpful tools for a safe return to play to properly address CMR studies. Trial registration: the study protocol was registered in the PROSPERO database (registration number: CRD42022300819).

Cardiovascular Magnetic Resonance for Patients With COVID-19

COVID-19 is associated with myocardial injury caused by ischemia, inflammation, or myocarditis. Cardiovascular magnetic resonance (CMR) is the noninvasive reference standard for cardiac function, structure, and tissue composition. CMR is a potentially valuable diagnostic tool in patients with COVID-19 presenting with myocardial injury and evidence of cardiac dysfunction. Although COVID-19-related myocarditis is likely infrequent, COVID-19-related cardiovascular histopathology findings have been reported in up to 48% of patients, raising the concern for long-term myocardial injury. Studies to date report CMR abnormalities in 26% to 60% of hospitalized patients who have recovered from COVID-19, including functional impairment, myocardial tissue abnormalities, late gadolinium enhancement, or pericardial abnormalities. In athletes post-COVID-19, CMR has detected myocarditis-like abnormalities. In children, multisystem inflammatory syndrome may occur 2 to 6 weeks after infection; associated myocarditis and coronary artery aneurysms are evaluable by CMR. At this time, our understanding of COVID-19-related cardiovascular involvement is incomplete, and multiple studies are planned to evaluate patients with COVID-19 using CMR. In this review, we summarize existing studies of CMR for patients with COVID-19 and present ongoing research. We also provide recommendations for clinical use of CMR for patients with acute symptoms or who are recovering from COVID-19.

Cardiac Magnetic Resonance in the Evaluation of COVID-19

Cardiovascular involvement following COVID-19 is heterogeneous, prevalent and is often missed by echocardiography and serum biomarkers (such as troponin I and brain natriuretic peptide). Cardiac magnetic resonance (CMR) is the gold standard non-invasive imaging modality to phenotype unique populations after COVID-19, such as competitive athletes with a heightened risk of sudden cardiac death, patients with multisystem inflammatory syndrome, and people suspected of having COVID-19 vaccine-induced myocarditis. This review summarises the key attributes of CMR, reviews the literature that has emerged for using CMR for people who may have COVID-19-related complications after COVID-19, and offers expert opinion regarding future avenues of investigation and the importance of reporting findings.

Myocardial Extracellular Volume Fraction Measured by Cardiac Magnetic Resonance Imaging Negatively Correlates With Cardiomyocyte Breadth in a Healthy Porcine Model

Background

The extracellular volume fraction (ECV) derived from cardiac magnetic resonance imaging (MRI) is extensively used to evaluate myocardial fibrosis. However, due to the limited histological verification in healthy individuals, it remains unclear whether the size of cardiomyocytes may play a potential role in the physiological changes of ECV. The aim of this study was to examine the association between cardiomyocyte size and myocardial ECV by using a healthy porcine model.

Methods

Sixteen domestic healthy pigs were anesthetized and underwent cardiac MRI with mechanical controlled breathing. Intravenous contrast medium was introduced at a dose of 0.2–0.25 mmol/kg. The interventricular septum ECV was calculated using an established MRI procedure, which was based on the pre- and post-contrast T1 values of the heart and individual blood hematocrit. The cardiomyocyte breadth (CmyB) in cross section was measured by hematoxylin and eosin staining to reflect the cardiomyocyte size.

Results

Data were successfully acquired from 14 pigs. The CmyB was obtained from the myocardial tissues corresponding to the region of interest on cardiac MRI. The mean ± SD of the ECV was 0.253 ± 0.043, and the mean ± SD of the CmyB was 10.02 ± 0.84 μm. The ECV exhibited a negative correlation with the CmyB (r = −0.729, p = 0.003).

Conclusion

The myocardial ECV detected by cardiac MRI is negatively correlated with the CmyB in healthy pigs, demonstrating that the size of cardiomyocytes is potentially associated with the ECV under physiological conditions.

2021 - State of our JCMR

There were 89 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2020, including 71 original research papers, 5 technical notes, 6 reviews, 4 Society for Cardiovascular Magnetic Resonance (SCMR) position papers/guidelines/protocols and 3 corrections. The volume was up 12.7% from 2019 (n = 79) with a corresponding 17.9% increase in manuscript submissions from 369 to 435. This led to a slight increase in the acceptance rate from 22 to 23%. The quality of the submissions continues to be high. The 2020 JCMR Impact Factor (which is published in June 2020) slightly increased from 5.361 to 5.364 placing us in the top quartile of Society and cardiac imaging journals. Our 5 year impact factor increased from 5.18 to 6.52. Fourteen years ago, the JCMR was at the forefront of medical and medical society journal migration to the Open-Access format. The Open-Access system has dramatically increased the availability and citation of JCMR publications with accesses now exceeding 1.2 M! It takes a village to run a journal. JCMR is blessed to have a group of very dedicated Associate Editors, Guest Editors, Journal Club Editors, and Reviewers. I thank each of them for their efforts to ensure that the review process occurs in a timely and responsible manner. These efforts have allowed the JCMR to continue as the premier journal of our field. My role, and the entire process would not be possible without the dedication and efforts of our new managing editor, Jennifer Rodriguez, whose premier organizational efforts have allowed for streamlining of the review process and marked improvement in our time-to-decision (see later). As I begin my 6th and final year as your editor-in-chief, I thank you for entrusting me with the JCMR editorship. I hope that you will continue to send us your very best, high quality manuscripts for JCMR consideration and that our readers will continue to look to JCMR for the very best/state-of-the-art CMR publications. The editorial process continues to be a tremendously fulfilling experience and the opportunity to review manuscripts that reflect the best in our field remains a great joy and true highlight of my week!

Subclinical Hypertrophic Cardiomyopathy in Elite Athletes: Knowledge Gaps Persist

Subclinical hypertrophic cardiomyopathy (HCM) is a phenotypic entity that has emerged from the increased use of cardiovascular magnetic resonance imaging in the evaluation and family screening of patients with HCM. We describe the case of a competitive athlete with a sarcomere gene mutation and family history of HCM who was found to exhibit the subclinical HCM phenotype on cardiovascular magnetic resonance imaging in the absence of left ventricular hypertrophy. We discuss the clinical uncertainties in her management. (Level of Difficulty: Advanced.).

Role of Cardiac Magnetic Resonance Imaging in the Evaluation of Athletes with Premature Ventricular Beats

Premature ventricular beats (PVBs) in athletes are not rare. The risk of PVBs depends on the presence of an underlying pathological myocardial substrate predisposing the subject to sudden cardiac death. The standard diagnostic work-up of athletes with PVBs includes an examination of family and personal history, resting electrocardiogram (ECG), 24 h ambulatory ECG (possibly with a 12-lead configuration and including a training session), maximal exercise testing and echocardiography. Despite its fundamental role in the diagnostic assessment of athletes with PVBs, echocardiography has very limited sensitivity in detecting the presence of non-ischemic left ventricular scars, which can be revealed only through more in-depth studies, particularly with the use of contrast-enhanced cardiac magnetic resonance (CMR) imaging. The morphology, complexity and exercise inducibility of PVBs can help estimate the probability of an underlying heart disease. Based on these features, CMR imaging may be indicated even when echocardiography is normal. This review focuses on interpreting PVBs, and on the indication and role of CMR imaging in the diagnostic evaluation of athletes, with a special focus on non-ischemic left ventricular scars that are an emerging substrate of cardiac arrest during sport.

The Role of Cardiovascular Magnetic Resonance Imaging in the Assessment of Myocardial Fibrosis in Young and Veteran Athletes: Insights From a Meta-Analysis

Background: Cardiac magnetic resonance (CMR) combined with late gadolinium enhancement (LGE) has revealed a non-negligible increased incidence of myocardial fibrosis (MF) in athletes compared to healthy sedentary controls.

Objective: The aim of this systematic research and meta-analysis is to investigate and present our perspective regarding CMR indices in athletes compared to sedentary controls, including T1 values, myocardial extracellular volume (ECV) and positive LGE indicative of non-specific fibrosis, also to discuss the differences between young and veteran athletes.

Methods: The protocol included searching, up to October 2021, of MEDLINE, EMBASE, SPORTDiscus, Web of Science and Cochrane databases for original studies assessing fibrosis via CMR in athletes. A mean age of 40 years differentiated studies' athletic populations to veteran and young.

Results: The research yielded 14 studies including in total 1,312 individuals. There was a statistically significant difference in LGE fibrosis between the 118/759 athletes and 16/553 controls (Z = 5.2, P < 0.001, I² = 0%, P_I = 0.45). Notably, LGE fibrosis differed significantly between 546 (14.6%) veteran and 140 (25.7%) young athletes (P = 0.002). At 1.5T, T1 values differed between 117 athletes and 48 controls (P < 0.0001). A statistically significant difference was also shown at 3T (110 athletes vs. 41 controls, P = 0.0004), as well as when pooling both 1.5T and 3T populations (P < 0.00001). Mean ECV showed no statistically significant difference between these groups.

Conclusions: Based on currently available data, we reported that overall LGE based non-specific fibrosis and T1 values differ between athletes and sedentary controls, in contrast to ECV values. Age of athletes seems to have impact on the incidence of MF. Future prospective studies should focus on the investigation of the underlying pathophysiological mechanisms.

Exercise and the Female Heart

Female participation in sport has increased sharply during the last few decades, and for the third straight Olympic Games, there were more women than men on the US roster for the 2020 Tokyo Games. Given this, an understanding of the differences between men and women with respect to exercise-induced cardiac remodeling is critical for those caring for female athletes. Recent studies have provided insight into female-specific cardiac remodeling and have enhanced our understanding on the upper limits of cardiac remodeling in female athletes and how these adaptations compare with sedentary females, male athletes, and cardiomyopathies. Female athletes display fewer signs of adaptive remodeling on ECG compared with male athletes. Structurally, male athletes have larger absolute cardiac dimensions, but female athletes have similar or larger chamber size when adjusted for body size. Female athletes have a lower incidence of sudden cardiac arrest or death compared with male athletes in the early competitive years (high school, college, and professional) and in the masters athlete years. In addition, female athletes are less likely to have coronary disease and atrial fibrillation compared with male athletes. Data on longevity indicate that female athletes live longer than their sedentary counterparts. Unlike men, there has been no convincing association of extreme exercise and cardiovascular disease in longer-term endurance female athletes. The underlying mechanisms of these sex-based differences are not very well understood, and future studies are warranted to better understand the mechanisms of cardiac adaptation in female athletes.

Is cardiac involvement prevalent in highly trained athletes after SARS-CoV-2 infection? A cardiac magnetic resonance study using sex-matched and age-matched controls

Objectives

To investigate the cardiovascular consequences of SARS-CoV-2 infection in highly trained, otherwise healthy athletes using cardiac magnetic resonance (CMR) imaging and to compare our results with sex-matched and age-matched athletes and less active controls.

Methods

SARS-CoV-2 infection was diagnosed by PCR on swab tests or serum immunoglobulin G antibody tests prior to a comprehensive CMR examination. The CMR protocol contained sequences to assess structural, functional and tissue-specific data.

Results

One hundred forty-seven athletes (94 male, median 23, IQR 20–28 years) after SARS-CoV-2 infection were included. Overall, 4.7% (n=7) of the athletes had alterations in their CMR as follows: late gadolinium enhancement (LGE) showing a non-ischaemic pattern with or without T2 elevation (n=3), slightly elevated native T1 values with or without elevated T2 values without pathological LGE (n=3) and pericardial involvement (n=1). Only two (1.4%) athletes presented with definite signs of myocarditis. We found pronounced sport adaptation in both athletes after SARS-CoV-2 infection and athlete controls. There was no difference between CMR parameters, including native T1 and T2 mapping, between athletes after SARS-CoV-2 infection and the matched athletic groups. Comparing athletes with different symptom severities showed that athletes with moderate symptoms had slightly greater T1 values than athletes with asymptomatic and mildly symptomatic infections (p<0.05). However, T1 mapping values remained below the cut-off point for most patients.

Conclusion

Among 147 highly trained athletes after SARS-CoV-2 infection, cardiac involvement on CMR showed a modest frequency (4.7%), with definite signs of myocarditis present in only 1.4%. Comparing athletes after SARS-CoV-2 infection and healthy sex-matched and age-matched athletes showed no difference between CMR parameters, including native T1 and T2 values.

Cardiovascular magnetic resonance evaluation of soldiers after recovery from symptomatic SARS-CoV-2 infection: a case-control study of cardiovascular post-acute sequelae of SARS-CoV-2 infection (CV PASC)

BACKGROUND

Myocarditis is a potential complication after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and a known cause of sudden cardiac death. Given the athletic demands of soldiers, identification of myocarditis and characterization of post-acute sequelae of SARS-CoV-2 infection with cardiovascular symptoms (CV PASC) may be critical to guide return-to-service. This study sought to evaluate the spectrum of cardiac involvement among soldiers with cardiopulmonary symptoms in the late convalescent phase of recovery from SARS-CoV-2 compared to a healthy soldier control group, and to determine the rate of progression to CV PASC.

METHODS

All soldiers referred for cardiovascular magnetic resonance (CMR) imaging for cardiopulmonary symptoms following COVID-19 were enrolled and matched by age, gender, and athletic phenotype 1:1 to soldiers undergoing CMR in the year prior to the first case of COVID-19 at our institution. Demographic, clinical, laboratory, and imaging parameters were compared between groups. The diagnosis of acute myocarditis was made using modified Lake Louise criteria. Wilcoxon rank sum and chi-squared tests were used for comparison of continuous and categorical variables, respectively.

RESULTS

Fifty soldier cases and 50 healthy soldier controls were included. The median time from SARS-CoV-2 detection to CMR was 71 days. The majority of cases experienced moderate symptoms (N = 43, 86%), while only 10% required hospitalization. The right ventricular (RV) ejection fraction (RVEF) was reduced in soldier cases compared to controls (51.0% vs. 53.2%, p = 0.012). Four cases were diagnosed with myocarditis (8%), 1 (2%) was diagnosed with Takotsubo cardiomyopathy, and 1 (2%) had new biventricular systolic dysfunction of unclear etiology. Isolated inferior RV septal insertion late gadolinium enhancement (LGE) was present in 8 cases and 8 controls (16% vs. 24%, p = 0.09). Seven of the 19 (37%) cases that completed an intermediate-term follow-up survey reported CV PASC at a median of 139 days of follow-up. Two of the 7 soldiers (29%) with CV PASC had a pathological clinical diagnosis (myocarditis) on CMR.

CONCLUSIONS

Cardiovascular pathology was diagnosed in 6 symptomatic soldiers (12%) after recovery from SARS-CoV-2, with myocarditis found in 4 (8%). RVEF was reduced in soldier cases compared to controls. CV PASC occurred in over one-third of soldiers surveyed, but did not occur in any soldiers with asymptomatic acute SARS-CoV-2 infection.

Evaluation for Myocarditis in Competitive Student Athletes Recovering From Coronavirus Disease 2019 With Cardiac Magnetic Resonance Imaging

Importance

The utility of cardiac magnetic resonance imaging (MRI) as a screening tool for myocarditis in competitive student athletes returning to training after recovering from coronavirus disease 2019 (COVID-19) infection is unknown.

Objective

To describe the prevalence and severity of cardiac MRI findings of myocarditis in a population of competitive student athletes recovering from COVID-19.

Design, Setting, and Participants

In this case series, an electronic health record search was performed at our institution (University of Wisconsin) to identify all competitive athletes (a consecutive sample) recovering from COVID-19, who underwent gadolinium-enhanced cardiac MRI between January 1, 2020, and November 29, 2020. The MRI findings were reviewed by 2 radiologists experienced in cardiac imaging, using the updated Lake Louise criteria. Serum markers of myocardial injury and inflammation (troponin-I, B-type natriuretic peptide, C-reactive protein, and erythrocyte sedimentation rate), an electrocardiogram, transthoracic echocardiography, and relevant clinical data were obtained.

Exposures

COVID-19 infection, confirmed using reverse transcription-polymerase chain reaction testing.

Main Outcomes and Measures

Prevalence and severity of MRI findings consistent with myocarditis among young competitive athletes recovering from COVID-19.

Results

A total of 145 competitive student athletes (108 male and 37 female individuals; mean age, 20 years; range, 17-23 years) recovering from COVID-19 were included. Most patients had mild (71 [49.0%]) or moderate (40 [27.6%]) symptoms during the acute infection or were asymptomatic (24 [16.6%]). Symptoms were not specified or documented in 10 patients (6.9%). No patients required hospitalization. Cardiac MRIs were performed a median of 15 days (range, 11-194 days) after patients tested positive for COVID-19. Two patients had MRI findings consistent with myocarditis (1.4% [95% CI, 0.4%-4.9%]). Of these, 1 patient had marked nonischemic late gadolinium enhancement and T2-weighted signal abnormalities over multiple segments, along with an abnormal serum troponin-I level; the second patient had 1-cm nonischemic mild late gadolinium enhancement and mild T2-weighted signal abnormalities, with normal laboratory values.

Conclusions and Relevance

In this case series study, based on MRI findings, there was a low prevalence of myocarditis (1.4%) among student athletes recovering from COVID-19 with no or mild to moderate symptoms. Thus, the utility of cardiac MRI as a screening tool for myocarditis in this patient population is questionable.

The role of cardiovascular magnetic resonance in the screening before the return-to-play of elite athletes after COVID-19: utility o futility?

Recent reports based on cardiovascular magnetic resonance (CMR) showed a wide range of prevalence of inflammatory heart diseases in COVID-19 convalescent athletes ranging from 0.4 up to 15%. These observations had an important impact in the field of sport cardiology opening an intense debate around the best possible screening strategy before the return-to-play. The diagnostic yield of CMR for detecting acute inflammatory disease is undebatable. However, the opportunity to use it in the screening protocol after COVID-19 has been questioned. Current evidence does not seem to support the routine use of CMR and the prescription of CMR should be based upon clinical indication.

Cardiac Biomarkers and Autoantibodies in Endurance Athletes: Potential Similarities with Arrhythmogenic Cardiomyopathy Pathogenic Mechanisms

The “Extreme Exercise Hypothesis” states that when individuals perform training beyond the ideal exercise dose, a decline in the beneficial effects of physical activity occurs. This is due to significant changes in myocardial structure and function, such as hemodynamic alterations, cardiac chamber enlargement and hypertrophy, myocardial inflammation, oxidative stress, fibrosis, and conduction changes. In addition, an increased amount of circulating biomarkers of exercise-induced damage has been reported. Although these changes are often reversible, long-lasting cardiac damage may develop after years of intense physical exercise. Since several features of the athlete’s heart overlap with arrhythmogenic cardiomyopathy (ACM), the syndrome of “exercise-induced ACM” has been postulated. Thus, the distinction between ACM and the athlete’s heart may be challenging. Recently, an autoimmune mechanism has been discovered in ACM patients linked to their characteristic junctional impairment. Since cardiac junctions are similarly impaired by intense physical activity due to the strong myocardial stretching, we propose in the present work the novel hypothesis of an autoimmune response in endurance athletes. This investigation may deepen the knowledge about the pathological remodeling and relative activated mechanisms induced by intense endurance exercise, potentially improving the early recognition of whom is actually at risk.

Prevalence of Clinical and Subclinical Myocarditis in Competitive Athletes With Recent SARS-CoV-2 Infection: Results From the Big Ten COVID-19 Cardiac Registry

Question

What is the prevalence of myocarditis in competitive athletes after COVID-19 infection, and how would different approaches to screening affect detection?

Findings

In this cohort study of 1597 US competitive collegiate athletes undergoing comprehensive cardiovascular testing, the prevalence of clinical myocarditis based on a symptom-based screening strategy was only 0.31%. Screening with cardiovascular magnetic resonance imaging increased the prevalence of clinical and subclinical myocarditis by a factor of 7.4 to 2.3%.

Meaning

These cardiac magnetic resonance imaging findings provide important data on the prevalence of clinical and subclinical myocarditis in college athletes recovering from symptomatic and asymptomatic COVID-19 infections.

Importance

Myocarditis is a leading cause of sudden death in competitive athletes. Myocardial inflammation is known to occur with SARS-CoV-2. Different screening approaches for detection of myocarditis have been reported. The Big Ten Conference requires comprehensive cardiac testing including cardiac magnetic resonance (CMR) imaging for all athletes with COVID-19, allowing comparison of screening approaches.

Objective

To determine the prevalence of myocarditis in athletes with COVID-19 and compare screening strategies for safe return to play.

Design, Setting, and Participants

Big Ten COVID-19 Cardiac Registry principal investigators were surveyed for aggregate observational data from March 1, 2020, through December 15, 2020, on athletes with COVID-19. For athletes with myocarditis, presence of cardiac symptoms and details of cardiac testing were recorded. Myocarditis was categorized as clinical or subclinical based on the presence of cardiac symptoms and CMR findings. Subclinical myocarditis classified as probable or possible myocarditis based on other testing abnormalities. Myocarditis prevalence across universities was determined. The utility of different screening strategies was evaluated.

Exposures

SARS-CoV-2 by polymerase chain reaction testing.

Main Outcome and Measure

Myocarditis via cardiovascular diagnostic testing.

Results

Representing 13 universities, cardiovascular testing was performed in 1597 athletes (964 men [60.4%]). Thirty-seven (including 27 men) were diagnosed with COVID-19 myocarditis (overall 2.3%; range per program, 0%-7.6%); 9 had clinical myocarditis and 28 had subclinical myocarditis. If cardiac testing was based on cardiac symptoms alone, only 5 athletes would have been detected (detected prevalence, 0.31%). Cardiac magnetic resonance imaging for all athletes yielded a 7.4-fold increase in detection of myocarditis (clinical and subclinical). Follow-up CMR imaging performed in 27 (73.0%) demonstrated resolution of T2 elevation in all (100%) and late gadolinium enhancement in 11 (40.7%).

Conclusions and Relevance

In this cohort study of 1597 US competitive athletes with CMR screening after COVID-19 infection, 37 athletes (2.3%) were diagnosed with clinical and subclinical myocarditis. Variability was observed in prevalence across universities, and testing protocols were closely tied to the detection of myocarditis. Variable ascertainment and unknown implications of CMR findings underscore the need for standardized timing and interpretation of cardiac testing. These unique CMR imaging data provide a more complete understanding of the prevalence of clinical and subclinical myocarditis in college athletes after COVID-19 infection. The role of CMR in routine screening for athletes safe return to play should be explored further.

Cardiac MRI findings to differentiate athlete's heart from hypertrophic (HCM), arrhythmogenic right ventricular (ARVC) and dilated (DCM) cardiomyopathy

To provide clinically relevant criteria for differentiation between the athlete’s heart and similar appearing hypertrophic (HCM), dilated (DCM), and arrhythmogenic right-ventricular cardiomyopathy (ARVC) in MRI. 40 top-level athletes were prospectively examined with cardiac MR (CMR) in two university centres and compared to retrospectively recruited patients diagnosed with HCM (n = 14), ARVC (n = 18), and DCM (n = 48). Analysed MR imaging parameters in the whole study cohort included morphology, functional parameters and late gadolinium enhancement (LGE). Mean left-ventricular enddiastolic volume index (LVEDVI) was high in athletes (105 ml/m²) but significantly lower compared to DCM (132 ml/m²; p = 0.001). Mean LV ejection fraction (EF) was 61% in athletes, below normal in 7 (18%) athletes vs. EF 29% in DCM, below normal in 46 (96%) patients (p < 0.0001). Mean RV-EF was 54% in athletes vs. 60% in HCM, 46% in ARVC, and 41% in DCM (p < 0.0001). Mean interventricular myocardial thickness was 10 mm in athletes vs. 12 mm in HCM (p = 0.0005), 9 mm in ARVC, and 9 mm in DCM. LGE was present in 1 (5%) athlete, 8 (57%) HCM, 10 (56%) ARVC, and 21 (44%) DCM patients (p < 0.0001). Healthy athletes’ hearts are characterized by both hypertrophy and dilation, low EF of both ventricles at rest, and increased interventricular septal thickness with a low prevalence of LGE. Differentiation of athlete’s heart from other non-ischemic cardiomyopathies in MRI can be challenging due to a significant overlap of characteristics also seen in HCM, ARVC, and DCM.

Myocardial Injury and Fibrosis From Acute Carbon Monoxide Poisoning: A Prospective Observational Study

OBJECTIVES

This study sought to evaluate the prevalence and patterns of late gadolinium enhancement (LGE) after carbon monoxide (CO) poisoning using cardiac magnetic resonance (CMR) imaging (CMRI) and transthoracic echocardiography (TTE).

BACKGROUND

In acute CO poisoning, cardiac injury can predict mortality. However, it remains unclear why increased mortality and cardiovascular events occur despite normalization of CO-induced elevated troponin I (TnI) and cardiac dysfunction.

METHODS

Patients with acute CO poisoning with elevated TnI were evaluated. CMRI was performed within 7 days of CO exposure and after 4 to 5 months. Patients were divided into LGE (n = 72; 69.2%) and no-LGE (n = 32; 30.8%) groups.

RESULTS

In the LGE group, 39.4%, 4.8%, and 25.0% of patients exhibited midwall, subendocardial, and right ventricular insertion point injury, respectively. Diffuse injury was observed in 22.1% of patients, and 67.6% of the 37 patients who underwent follow-up CMRI showed no interval change. On TTE, baseline left ventricular ejection fraction and global longitudinal strain were significantly deteriorated in the LGE group; serial TTE within 7 days indicated that only left ventricular global longitudinal strain remained significantly deteriorated. Three cases of mortality occurred in the LGE group during the 1-year follow-up.

CONCLUSIONS

The LGE prevalence in patients with acute CO poisoning with elevated TnI levels, with no underlying cardiovascular diseases and eligible for CMRI, was 69.2%; this proportion primarily comprised patients with a midwall injury. Of the 37 patients who underwent follow-up CMRI, most chronic phase images showed no interval change. Myocardial fibrosis detected on CMR images was related to acute myocardial dysfunction and subacute deterioration of myocardial strain on TTE. (Cardiac Magnetic Resonance Image in Acute Carbon Monoxide Poisoning; NCT04419298).