Differentiating Athlete's Heart from Left Ventricle Cardiomyopathies

Quantification of Left Ventricular Trabecular Complexity in Patients With Hypertrophic Cardiomyopathy by Cardiovascular Magnetic Resonance Imaging Fractal Analysis: A Feasibility and Reproducibility Study

PURPOSE

To investigate the left ventricular (LV) trabecular complexity and evaluate its relationship with LV cardiac function and especially myocardial strain in patients with hypertrophic cardiomyopathy (HCM).

MATERIALS AND METHODS

A total of 100 patients were retrospectively recruited in the study, including 50 obstructive hypertrophic cardiomyopathy (HOCM) and 50 nonobstructive HCM (NOHCM). Fifty age-matched and sex-matched healthy participants were also enrolled. The global and regional LV fractal dimensions (FDs), the global radial, circumferential, and longitudinal strain (GRS, GCS, and GLS) for LV were measured. FDs and myocardial strain parameters among 3 groups with post hoc paired comparisons. Correlations analysis and receiver operating characteristic analysis were performed.

RESULTS

Mean global FD, max basal FD, and max apical FD were higher in patients with HCM compared with the healthy individuals (1.310 ± 0.046 vs 1.229 ± 0.027, 1.388 ± 0.089 vs 1.313 ± 0.039, 1.393 ± 0.108 vs 1.270 ± 0.041, all P < 0.001). Patients with HOCM showed significantly higher max apical FD than patients with NOHCM (1.432 ± 0.100 vs 1.355 ± 0.102, P < 0.001). The increased global FD was associated with reduced myocardial deformation across all 3 measures of global strain (GCS: r = 0.529, P < 0.001; GLS: r = 0.54, P < 0.001; GRS: r = -0.253, P = 0.002). Max apical FD yielded an area under the curve of 0.73 (95% CI: 0.63-0.83) for discriminating HOCM from NOHCM.

CONCLUSIONS

LV trabecular complexity is compensatively increased in patients with HCM and the max apical FD was more pronounced in patients with HOCM. The increased LV global trabecular complexity might be correlated with LV systolic dysfunction.

Metrnl and Cardiomyopathies: From Molecular Mechanisms to Therapeutic Insights

Cardiomyopathies, a diverse group of diseases affecting the heart muscle, continue to pose significant clinical challenges due to their complex aetiologies and limited treatment options targeting underlying genetic and molecular dysregulations. Emerging evidence indicates that Metrnl, a myokine, adipokine and cardiokine, plays a significant role in the pathogenesis of various cardiomyopathies. Therefore, the objective of this review is to examine the role and mechanism of Metrnl in various cardiomyopathies, with the expectation of providing new insights for the treatment of these diseases.

Advanced myocardial deformation echocardiography for evaluation of the athlete's heart: Functional and mechanistic analysis

BACKGROUND

Assessment of the athlete's heart is challenging because of a phenotypic overlap between reactive physiological adaptation and pathological remodelling. The potential value of myocardial deformation remains controversial in identifying early cardiomyopathy.

AIM

To identify the echocardiographic phenotype of athletes using advanced two-dimensional speckle tracking imaging, and to define predictive factors of subtle left ventricular systolic dysfunction.

METHODS

In total, 191 healthy male athletes who underwent a preparticipation medical evaluation at Nancy University Hospital between 2013 and 2020 were included. Clinical and echocardiographic data were compared with 161 healthy male subjects from the STANISLAS cohort. Borderline global longitudinal strain value was defined as<17.5%.

RESULTS

Athletes demonstrated lower left ventricular ejection fraction (57.9±5.3% vs. 62.6±6.4%; P<0.01) and lower global longitudinal strain (17.5±2.2% vs. 21.1±2.1%; P<0.01). No significant differences were found between athletes with and without a borderline global longitudinal strain value regarding clinical characteristics, structural echocardiographic features and exercise capacity. A borderline global longitudinal strain value was associated with a lower endocardial global longitudinal strain (18.8±1.2% vs. 22.7±1.9%; P=0.02), a lower epicardial global longitudinal strain (14.0±1.1% vs. 16.6±1.2%; P<0.01) and a higher endocardial/epicardial global longitudinal strain ratio (1.36±0.07 vs. 1.32±0.06; P<0.01). No significant difference was found regarding mechanical dispersion (P=0.46).

CONCLUSIONS

Borderline global longitudinal strain value in athletes does not appear to be related to structural remodelling, mechanical dispersion or exercise capacity. The athlete's heart is characterized by a specific myocardial deformation pattern with a more pronounced epicardial layer strain impairment.

Reference ventricular dimensions and function parameters by cardiovascular magnetic resonance in highly trained Caucasian athletes

BACKGROUND

Data regarding cardiovascular magnetic resonance (CMR) reference values in athletes have not been well determined yet. Using CMR normal reference values derived from the general population may be misleading in athletes and may have clinical implications.

AIMS

To determine reference ventricular dimensions and function parameters and ratios by CMR in high performance athletes.

METHODS

Elite athletes and age- and gender-matched sedentary healthy controls were included. Anatomical and functional variables, including biventricular volumes, mass, systolic function, wall thickness, sphericity index and longitudinal function were determined by CMR.

RESULTS

A total of 148 athletes (29.2 ± 9.1 years; 64.8% men) and 124 controls (32.1 ± 10.5 years; 67.7% men) were included. Left ventricular (LV) mass excluding papillary muscles was 67 ± 13 g/m2 in the control group and increased from 65 ± 14 g/m2 in the low intensity sport category to 83 ± 16 g/m2 in the high cardiovascular demand sport category; P < 0.001. Regarding right ventricular (RV) mass, the data were 20 ± 5, 31 ± 6, and 38 ± 8 g/m2, respectively; P < 0.001. LV and RV volumes, and wall thickness were higher in athletes than in the control group, and also increased with sport category. However, LV and RV ejection fractions were similar in both groups. LV and RV dimensions, wall thickness and LV/RV ratios reference parameters for athletes are provided.

CONCLUSIONS

LV and RV masses, volumes, and wall thicknesses are higher in athletes than in sedentary subjects. Specific CMR reference ranges for athletes are provided and can be used as reference levels, rather than the standard upper limits used for the general population to exclude cardiomyopathy.

Mitochondrial mutations alter endurance exercise response and determinants in mice

Primary mitochondrial diseases (PMDs) are the most prevalent inborn metabolic disorders, affecting an estimated 1 in 4,200 individuals. Endurance exercise is generally known to improve mitochondrial function, but its indication in the heterogeneous group of PMDs is unclear. We determined the relationship between mitochondrial mutations, endurance exercise response, and the underlying molecular pathways in mice with distinct mitochondrial mutations. This revealed that mitochondria are crucial regulators of exercise capacity and exercise response. Endurance exercise proved to be mostly beneficial across the different mitochondrial mutant mice with the exception of a worsened dilated cardiomyopathy in ANT1-deficient mice. Thus, therapeutic exercises, especially in patients with PMDs, should take into account the physical and mitochondrial genetic status of the patient.

Primary mitochondrial diseases (PMDs) are a heterogeneous group of metabolic disorders that can be caused by hundreds of mutations in both mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) genes. Current therapeutic approaches are limited, although one approach has been exercise training. Endurance exercise is known to improve mitochondrial function in heathy subjects and reduce risk for secondary metabolic disorders such as diabetes or neurodegenerative disorders. However, in PMDs the benefit of endurance exercise is unclear, and exercise might be beneficial for some mitochondrial disorders but contraindicated in others. Here we investigate the effect of an endurance exercise regimen in mouse models for PMDs harboring distinct mitochondrial mutations. We show that while an mtDNA ND6 mutation in complex I demonstrated improvement in response to exercise, mice with a CO1 mutation affecting complex IV showed significantly fewer positive effects, and mice with an ND5 complex I mutation did not respond to exercise at all. For mice deficient in the nDNA adenine nucleotide translocase 1 (Ant1), endurance exercise actually worsened the dilated cardiomyopathy. Correlating the gene expression profile of skeletal muscle and heart with the physiologic exercise response identified oxidative phosphorylation, amino acid metabolism, matrisome (extracellular matrix [ECM]) structure, and cell cycle regulation as key pathways in the exercise response. This emphasizes the crucial role of mitochondria in determining the exercise capacity and exercise response. Consequently, the benefit of endurance exercise in PMDs strongly depends on the underlying mutation, although our results suggest a general beneficial effect.

Cardiac Imaging in Athlete's Heart: The Role of the Radiologist

Athlete's heart (AH) is the result of morphological and functional cardiac modifications due to long-lasting athletic training. Athletes can develop very marked structural myocardial changes, which may simulate or cover unknown cardiomyopathies. The differential diagnosis between AH and cardiomyopathy is necessary to prevent the risk of catastrophic events, such as sudden cardiac death, but it can be a challenging task. The improvement of the imaging modalities and the introduction of the new technologies in cardiac magnetic resonance (CMR) and cardiac computed tomography (CCT) can allow overcoming this challenge. Therefore, the radiologist, specialized in cardiac imaging, could have a pivotal role in the differential diagnosis between structural adaptative changes observed in the AH and pathological anomalies of cardiomyopathies. In this review, we summarize the main CMR and CCT techniques to evaluate the cardiac morphology, function, and tissue characterization, and we analyze the imaging features of the AH and the key differences with the main cardiomyopathies.

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.