The Use of Speckle Tracking Echocardiography for Early Detection of Myocardial Dysfunction in Patients with Duchenne Muscular Dystrophy

Cardiomyopathy in Duchenne Muscular Dystrophy and the Potential for Mitochondrial Therapeutics to Improve Treatment Response

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease caused by mutations to the dystrophin gene, resulting in deficiency of dystrophin protein, loss of myofiber integrity in skeletal and cardiac muscle, and eventual cell death and replacement with fibrotic tissue. Pathologic cardiac manifestations occur in nearly every DMD patient, with the development of cardiomyopathy-the leading cause of death-inevitable by adulthood. As early cardiac abnormalities are difficult to detect, timely diagnosis and appropriate treatment modalities remain a challenge. There is no cure for DMD; treatment is aimed at delaying disease progression and alleviating symptoms. A comprehensive understanding of the pathophysiological mechanisms is crucial to the development of targeted treatments. While established hypotheses of underlying mechanisms include sarcolemmal weakening, upregulation of pro-inflammatory cytokines, and perturbed ion homeostasis, mitochondrial dysfunction is thought to be a potential key contributor. Several experimental compounds targeting the skeletal muscle pathology of DMD are in development, but the effects of such agents on cardiac function remain unclear. The synergistic integration of small molecule- and gene-target-based drugs with metabolic-, immune-, or ion balance-enhancing compounds into a combinatorial therapy offers potential for treating dystrophin deficiency-induced cardiomyopathy, making it crucial to understand the underlying mechanisms driving the disorder.

Early assessment of cardiomyopathy in Duchenne patients by means of longitudinal strain echocardiography

INTRODUCTION

The diagnosis of Duchenne-linked cardiomyopathy may be challenging. Conventional echocardiographic measurements typically show deterioration beyond the second decade. Global longitudinal strain has been proposed as an earlier marker than left ventricular ejection fraction.

MATERIAL AND METHODS

A prospective, observational, cross-sectional, case-control study was carried out. Both Duchenne patients and control subjects underwent transthoracic echocardiogram in order to assess left ventricle function. Bayesian linear regression was the main tool for inference. Age effects were parameterised by means of a spline function because of its simplicity to characterise continuous variables and smooth contributions. The posterior distribution of the marginal age effects was used to assess the earliest age of deterioration of each marker.

RESULTS

Sixteen Duchenne patients and twenty-two healthy male subjects were enrolled. On overage, cardiac function measures were found for ejection fraction and longitudinal strain among different groups. Age effects on global longitudinal strain are more reliably found at ages of 6 and above, while ejection fraction starts to deteriorate at an older age. Progressive left ventricular dysfunction in Duchenne patients is one of the key issues and starts at an early age with subtle symptoms.

CONCLUSION

This cross-sectional study provides supporting evidence that global longitudinal strain is an earlier marker of disease progression than ejection fraction in Duchenne patients.

The effects of obesity on longitudinal ventricular and atrial strain in a rural population of Spanish children and adolescents, evaluated by a new strain software

BACKGROUND AND OBJECTIVES

Research on the relationship between body mass index (BMI) and strain values in children and adolescents is limited. Our aim was to analyse the relationship between BMI and strain values of both ventricles and left atrium in children and adolescents.

METHODS

Both ventricles and left atrial strain values were compared among different BMI categories in children and adolescents from a town in the South of Spain.

RESULTS

Of the 198 subjects, aged 6-17 years, 53% were of normal weight, 26% were overweight and 21% had obesity. Lower absolute values of left ventricular global longitudinal strain (25.9 ± 2.0% vs. 26.9 ± 2.2%, p = 0.002) and right ventricular free wall longitudinal strain (29.5 ± 4.2% vs. 30.8 ± 4.5%, p = 0.04) were found in subjects with obesity and overweight versus subjects with normal weight. A lower right ventricular four-chamber longitudinal strain was also observed in males with obesity and overweight (24.8 ± 3.3% vs. 26.4 ± 3.6%, p = 0.03). Statistically significant negative correlations of BMI were found for all ventricular, but not atrial, strain values in univariate analysis. This association turned non-significant for right ventricular four-chamber longitudinal strain in multivariate analysis.

CONCLUSIONS

Utilizing this new strain software, children and adolescents with high BMI were associated with significantly lower values for left and right ventricular free wall longitudinal strain, without impact in left atrial strain.

Gender differences in two-dimensional and three-dimensional speckle tracking echocardiography left ventricular measurements among healthy preschool pediatric population

BACKGROUND

Speckle-tracking echocardiography (STE) is an upcoming echocardiographic modality to measure global as well as segmental left ventricular systolic function expressed numerically as strain values independent of angle and ventricular geometry. We conducted this prospective study on 200 healthy preschool children with structurally normal hearts, to determine gender-based differences in two-dimensional (2D) global longitudinal strain (GLS) and three-dimensional (3D) GLS.

RESULTS

Age-matched 104 males and 96 females were included, 2D GLS results for the males showed longitudinal strain ranging from - 18.1 to - 29.8 with a mean of - 21.7202 ± 5.094322, while for females 2D GLS ranged from - 18.1 to - 30.7 with a mean of - 22.0646 ± 2.167802, also 3D GLS values were measured and compared based on gender, where 3D GLS in males ranged from - 18 to - 24 with a mean value of 20.49 ± 1.28, while for females ranged from - 17 to - 30 with a mean value of 20.47 ± 1.755. The gender-based difference for both 2D GLS and 3D GLS showed non-significant P values.

CONCLUSION

In healthy subjects below 6 years, 2D STE and 3D STE values showed no difference between males and females, unlike the adult population, to the best of our knowledge, this is one of the few studies in the literature that aims at comparing these measurements in the healthy pediatric group. In routine clinical practice, these values may be used to assess myocardial function or the early signs of malfunction.

Evaluation of Cardiac, Autonomic Functions in Ambulant Patients with Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder caused by dystrophin gene mutation resulting in muscle weakness, motor delays, difficulty in standing, and inability to walk by 12 years. As disease progresses, it leads to cardiac and respiratory failure. Evaluation of cardiac autonomic status and echocardiography in DMD patients at a young age can be a potential biomarker to assess disease progression. This study aimed to investigate the younger DMD population of 5-11years of age with mild to moderate cardiac involvement for early detection using non-invasive and cost-effective tools. Genetically confirmed male DMD patients, aged 5-11 years (n = 47), screened from the outpatient department of a tertiary neuroscience institution were subjected to heart rate variability and echocardiographic analysis, and values were correlated with their clinical variables. DMD patients showed a significantly higher difference in HR, interventricular septum, E m/s, and E-wave to A-wave (E/A) ratio than normal values (p < 0.001). Significantly higher HR indicates initial sinus tachycardia and decreased IVD (d), and increased E m/s and E/A ratio mark the onset of cardiac symptoms in DMD patients even though its chamber dimension remains normal and are associated with cardiac muscle fibrosis.

Cardiac MRI and Echocardiography for Early Diagnosis of Cardiomyopathy Among Boys With Duchenne Muscular Dystrophy: A Cross-Sectional Study

BACKGROUND

Cardiomyopathy is an important cause of morbidity and mortality in boys with Duchenne muscular dystrophy (DMD). Early diagnosis is a prerequisite for timely institution of cardioprotective therapies.

OBJECTIVE

We compared cardiac MRI (CMRI) with transthoracic echocardiography (TTE) including tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE) for diagnosis of cardiomyopathy in early ambulatory boys with DMD.

METHODOLOGY

This cross-sectional study was conducted between June 2018 and December 2020. Consecutive boys between 7 and 15 years of age with DMD were enrolled. Percentage ejection fraction (EF), fractional shortening, wall motion abnormalities, early diastolic mitral annulus velocity (Ea), medial mitral annulus ratio (E/Ea), and global strain were measured with STE. CMRI-derived EF, segmental hypokinesia, and late gadolinium enhancement (LGE) were studied and compared.

RESULTS

A total of 38 ambulatory boys with DMD were enrolled. The mean age was 8.8 ± 1.6 years, and none had clinical features suggestive of cardiac dysfunction. In the TTE, EF was ≤55% in 5 (15%), FS was ≤28% in 3 (9%), and one each had left ventricular wall thinning and wall hypokinesia. In TDI, none had diastolic dysfunction, and STE showed reduced global strain of < 18% in 3 (9%) boys. CMRI-derived EF was ≤55% in 20 (53%) boys and CMRI showed the presence of left ventricular wall hypokinesia in 9 (24%) and LGE in 4 (11%) boys.

CONCLUSION

Cardiomyopathy remains clinically asymptomatic among early ambulatory boys with DMD. A significantly higher percentage of boys revealed early features of DMD-related cardiomyopathy in CMRI in comparison with echocardiography.

Global longitudinal strain detects subtle left ventricular systolic dysfunction in Duchenne muscular dystrophy patients and carriers

Background

With the continuous improvement of the respiratory care of Duchenne muscular dystrophy patients, cardiac manifestations (heart failure and arrhythmias) become the leading causes of morbidity and mortality. Early identification of cardiac muscle affection is crucial to start anti-failure drugs that reverse remodeling and improve prognosis. This study aimed to detect subtle cardiac changes in Duchenne muscular dystrophy patients and carriers using electrocardiography and echocardiography.

Results

This study included genetically diagnosed Duchenne muscular dystrophy patients (28 males) and carriers (25 females) and compared them to healthy gender-matched control groups. All study participants underwent clinical assessment, 12-lead electrocardiography, and global longitudinal strain augmented echocardiography. In the current study, Duchenne muscular dystrophy patients had higher heart rates, smaller left ventricular internal diameters, left atrial diameter, lower ejection fraction, and worse left ventricular global longitudinal strain in comparison with the control group. The global longitudinal strain inversely correlated with the age of Duchenne muscular dystrophy patients. The number of exon mutations did not affect electrocardiography and echocardiographic findings. Exon mutations 45–47 and 51–54 were significantly associated with an ejection fraction less than 60%. Duchenne muscular dystrophy carriers had smaller left ventricular wall diameters, left ventricular end-diastolic diameter, left atrial diameter, and worse left ventricular global longitudinal strain in comparison with the control group.

Conclusions

Left ventricular global longitudinal strain could detect subtle left ventricular systolic dysfunction in Duchenne muscular dystrophy patients and carriers before the decline of left ventricular ejection fraction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43044-021-00214-0.

Intracavitary Electrocardiogram Guidance Aids Excavation of Rhythm Abnormalities in Patients with Occult Heart Disease

In this paper, the analysis of intracavitary electrocardiograms is used to guide the mining of abnormal cardiac rhythms in patients with hidden heart disease, and the algorithm is improved to address the data imbalance problem existing in the abnormal electrocardiogram signals, and a weight-based automatic classification algorithm for deep convolutional neural network electrocardiogram signals is proposed. By preprocessing the electrocardiogram data from the MIT-BIH arrhythmia database, the experimental dataset training algorithm model is obtained, and the algorithm model is migrated into the project. In terms of system design and implementation, by comparing the advantages and disadvantages of the electrocardiogram monitoring system platform, the overall design of the system was carried out in terms of functional and performance requirements according to the system realization goal, and a mobile platform system capable of classifying common abnormal electrocardiogram signals was developed. The system is capable of long-term monitoring and can invoke the automatic classification algorithm model of electrocardiogram signals for analysis. In this paper, the functional logic test and performance test were conducted on the main functional modules of the system. The test results show that the system can run stably and monitor electrocardiogram signals for a long time and can correctly call the deep convolutional neural network-based automatic electrocardiogram signal classification algorithm to analyze the electrocardiogram signals and achieve the requirements of displaying the electrocardiogram signal waveform, analyzing the heartbeat type, and calculating the average heart rate, which achieves the goal of real-time continuous monitoring and analysis of the electrocardiogram signals.

Early Myocardial Dysfunction and Benefits of Cardiac Treatment in Young X-Linked Duchenne Muscular Dystrophy Mice

CONTEXT

Duchenne muscular dystrophy (DMD) is associated with a progressive alteration in cardiac function.

OBJECTIVE

The aim of this study was to detect early cardiac dysfunction using the high sensitive two-dimensional speckle-tracking echocardiography (2D strain) in mdx mouse model and to investigate the potential preventive effects of the S107 ryanodine receptor (RyR2) stabilizer on early onset of DMD-related cardiomyopathy.

METHODS AND RESULTS

Conventional echocardiography and global and segmental left ventricle (LV) 2D strains were assessed in male mdx mice and control C57/BL10 mice from 2 to 12 months of age. Up to 12 months of age, mdx mice showed preserved myocardial function as assessed by conventional echocardiography. However, global longitudinal, radial, and circumferential LV 2D strains significantly declined in mdx mice compared to controls from the 9 months of age. Segmental 2D strain analysis found a predominant alteration in posterior, inferior, and lateral LV segments, with a more marked impairment with aging. Then, mdx mice were treated with S107 in the drinking water at a dose of 250 mg/L using two different protocols: earlier therapy from 2 to 6 months of age and later therapy from 6 to 9 months of age. The treatment with S107 was efficient only when administered earlier in very young animals (from 2 to 6 months of age) and prevented the segmental alterations seen in non-treated mdx mice.

CONCLUSIONS

This is the first animal study to evaluate the therapeutic effect of a drug targeting early onset of DMD-related cardiomyopathy, using 2D strain echocardiography. Speckle-tracking analyses revealed early alterations of LV posterior segments that could be prevented by 4 months of RyR2 stabilization.

Dystrophin Deficiency Causes Progressive Depletion of Cardiovascular Progenitor Cells in the Heart

Duchenne muscular dystrophy (DMD) is a devastating condition shortening the lifespan of young men. DMD patients suffer from age-related dilated cardiomyopathy (DCM) that leads to heart failure. Several molecular mechanisms leading to cardiomyocyte death in DMD have been described. However, the pathological progression of DMD-associated DCM remains unclear. In skeletal muscle, a dramatic decrease in stem cells, so-called satellite cells, has been shown in DMD patients. Whether similar dysfunction occurs with cardiac muscle cardiovascular progenitor cells (CVPCs) in DMD remains to be explored. We hypothesized that the number of CVPCs decreases in the dystrophin-deficient heart with age and disease state, contributing to DCM progression. We used the dystrophin-deficient mouse model (mdx) to investigate age-dependent CVPC properties. Using quantitative PCR, flow cytometry, speckle tracking echocardiography, and immunofluorescence, we revealed that young mdx mice exhibit elevated CVPCs. We observed a rapid age-related CVPC depletion, coinciding with the progressive onset of cardiac dysfunction. Moreover, mdx CVPCs displayed increased DNA damage, suggesting impaired cardiac muscle homeostasis. Overall, our results identify the early recruitment of CVPCs in dystrophic hearts and their fast depletion with ageing. This latter depletion may participate in the fibrosis development and the acceleration onset of the cardiomyopathy.

Impaired myocardial strain in early stage of Duchenne muscular dystrophy: its relation with age and motor performance

Duchenne muscular dystrophy (DMD) is complicated by an early and progressive left ventricular (LV) dysfunction. Despite the reduction of ejection fraction (EF) usually manifests in the second decade, subtle alterations in LV mechanics can be detected earlier. Longitudinal and circumferential LV deformation, evaluated by speckle tracking echocardiography (STE), are considered sensitive markers of early dysfunction. We retrospectively examined clinical and echocardiographic data of 32 DMD children with preserved LV function. According to the median age, patients were then divided into younger and older than 9 years, and compared to 24 age-matched healthy subjects. Six-minute-walk test (6MWT), North Star Ambulatory Assessment (NSAA), and a comprehensive cardiac evaluation were performed. Although EF was within the normal range, DMD patients had significantly lower values than healthy controls, and the same occurred for the remaining conventional systolic and diastolic indices. Global longitudinal strain (GLS) was reduced in all patients (older and younger, both p < 0.001). Global circumferential strain (GCS) was reduced only in older patients (< 0.001). Both GLS and GCS worsened with age in DMD patients (GLS p = 0.005; GCS p = 0.024). GLS was significantly worse in the apical segments and in the postero-lateral wall. GCS in the antero-septal, anterior and antero-lateral segments was significantly reduced in older patients, with a prevalent involvement of the sole septal wall in the younger boys. 6MWT appeared to be correlated inversely to GLS and directly to EF. A longitudinal evaluation should be scheduled in DMD boys to assess the global cardiac performance over time and to evaluate the impact of therapies.

Duchenne muscular dystrophy: an overview to the cardiologist

INTRODUCTION

Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy in children, affecting approximately one in 3,500-5,000 liveborn boys. The main signs and symptoms include gait disturbances beginning in early childhood, with later onset of respiratory and cardiac function disorders, both directly affecting the prognosis.

AREAS COVERED

The recent improvement of mechanical ventilation increased the mean DMD survival age; however, there has been little progress in the treatment and prevention of cardiac complications, which currently predominantly impact survival. Cardiological evaluation with imaging methods, such as echocardiography and magnetic resonance imaging, can improve the understanding and detect changes in cardiac function early.

EXPERT OPINION

Close monitoring by the cardiologists and early treatment, with adequate heart disease stratification, may be the key to prolong the lives of these patients until more promising therapies are available and can predict DMD prognosis and progression more accurately. The objective of this brief review is to update the cardiologists by highlighting the most relevant aspects of treatment and follow-up, in a practical and concise way.

Protective effects of rimeporide on left ventricular function in golden retriever muscular dystrophy dogs

BACKGROUND

Alterations in intracellular Na+ and Ca2+ have been observed in patients with Duchenne muscular dystrophy (DMD) and in animal models of DMD, and inhibition of Na+-H+ exchanger 1 (NHE1) by rimeporide has previously demonstrated cardioprotective effects in animal models of myocardial ischemia and heart failure. Since heart failure is becoming a predominant cause of death in DMD patients, this study aimed to demonstrate a cardioprotective effect of chronic administration of rimeporide in a canine model of DMD.

METHODS

Golden retriever muscular dystrophy (GRMD) dogs were randomized to orally receive rimeporide (10 mg/kg, twice a day) or placebo from 2 months to 1 year of age. Left ventricular (LV) function was assessed by conventional and advanced echocardiography.

RESULTS

Compared with placebo-treated GRMD, LV function deterioration with age was limited in rimeporide-treated GRMD dogs as indicated by the preservation of LV ejection fraction as well as overall cardiac parameters different from placebo-treated dogs, as revealed by composite cardiac scores and principal component analysis. In addition, principal component analysis clustered rimeporide-treated GRMD dogs close to healthy control dogs.

CONCLUSIONS

Chronic administration of the NHE1 inhibitor rimeporide exerted a protective effect against LV function decline in GRMD dogs. This study provides proof of concept to explore the cardiac effects of rimeporide in DMD patients.

Usefulness of speckle-tracking echocardiography for early detection in children with Duchenne muscular dystrophy: a meta-analysis and trial sequential analysis

Background

Duchenne muscular dystrophy (DMD) is the most common form of inherited muscle disease in children. The incidence of cardiomyopathy induced by DMD increases with age. Left ventricular ejection fraction usually fails to reflect the subclinical left ventricular dysfunction. Several studies have assessed this dysfunction using myocardial strain measured by speckle-tracking echocardiography (STE). However, the results were inconsistent and incomplete.

Methods

Several databases were searched from their inception to February 5, 2020. The summarized weighted mean difference (WMD) with 95% confidence intervals (CIs) were estimated for myocardial strain between DMD and healthy controls and a meta-analysis was conducted. Trial sequential analysis estimated whether the resulting evidence was sufficient.

Results

Eight studies with a total of 269 DMD children and 299 healthy participants were included. STE revealed that global longitudinal strain (GLS), global circumferential strain, average longitudinal strain (measured by two-dimensional STE at the apical four-chamber view), and average circumferential strain (measured by two-dimensional STE at the papillary muscle short-axis level) decreased (WMD = 4.17, 95% CI: 3.03–5.32; WMD = 3.98, 95% CI: 0.29–7.68; WMD = 4.18, 95% CI: 2.75–5.62; and WMD = 4.90, 95% CI: 2.38–7.43, respectively; all P < 0.05) compared with the controls and global radial strain was unchanged in the DMD group (WMD = − 4.33, 95% CI: − 9.53–0.87, P = 0.103). Trial sequential analysis indicated that available GLS samples were sufficient and confirmed that adequate evidence was accumulated. The credibility of other myocardial strains was questioned due to insufficiently involved studies.

Conclusion

GLS can be useful for early detection of left ventricle myocardial dysfunction in children with DMD.

Natural History of Cardiomyopathy in Adult Dogs With Golden Retriever Muscular Dystrophy

Background

Duchenne muscular dystrophy (DMD) is an X‐linked disease that causes progressive muscle weakness. Affected boys typically die from respiratory or cardiac failure. Golden retriever muscular dystrophy (GRMD) is genetically homologous with DMD and causes analogous skeletal and cardiac muscle disease. Previous studies have detailed features of GRMD cardiomyopathy in mostly young dogs. Cardiac disease is not well characterized in adult GRMD dogs, and cardiac magnetic resonance (CMR) imaging studies have not been completed.

Methods and Results

We evaluated echocardiography and CMR in 24 adult GRMD dogs at different ages. Left ventricular systolic and diastolic functions, wall thickness, and myocardial strain were assessed with echocardiography. Features evaluated with CMR included left ventricular function, chamber size, myocardial mass, and late gadolinium enhancement. Our results largely paralleled those of DMD cardiomyopathy. Ejection fraction and fractional shortening correlated well with age, with systolic dysfunction occurring at ≈30 to 45 months. Circumferential strain was more sensitive than ejection fraction in early disease detection. Evidence of left ventricular chamber dilatation provided proof of dilated cardiomyopathy. Late gadolinium enhancement imaging showed DMD‐like left ventricular lateral wall lesions and earlier involvement of the anterior septum. Multiple functional indexes were graded objectively and added, with and without late gadolinium enhancement, to give cardiac and cardiomyopathy scores of disease severity. Consistent with DMD, there was parallel skeletal muscle involvement, as tibiotarsal joint flexion torque declined in tandem with cardiac function.

Conclusions

This study established parallels of progressive cardiomyopathy between dystrophic dogs and boys, further validating GRMD as a model of DMD cardiac disease.

Risk Stratification of Genetic, Dilated Cardiomyopathies Associated With Neuromuscular Disorders: Role of Cardiac Imaging

The etiology of dilated cardiomyopathy (DCM) can be grouped as either genetic or nongenetic. More than 50 pathogenic genes have been described, with sarcomeric and lamin A/C mutations being the most common. Mutation carriers for genetic DCM are often asymptomatic until cardiac disease manifests with heart failure, arrhythmias, or sudden cardiac death. Preventive strategies are promising but can only be applied and tested adequately if genetic DCM can be diagnosed at an early stage. Early diagnosis of mutation carriers that may develop overt DCM requires advanced imaging techniques that can detect subtle structural and functional abnormalities. Advanced echocardiographic techniques such as tissue Doppler imaging and speckle tracking strain analysis permit early detection of functional abnormalities, whereas cardiovascular magnetic resonance techniques provide information on tissue characterization and myocardial energetics that may be altered at an early stage. Furthermore, nuclear imaging techniques provide information on cellular function (metabolism, perfusion). Once the diagnosis of overt DCM has been established, various imaging parameters such as echocardiography-based myocardial mechanics and cardiovascular magnetic resonance-based tissue characterization have shown incremental benefit to left ventricular ejection fraction in risk stratification. Further research is required to understand how imaging techniques may help to choose management strategies that could delay progression when instituted early in the course of the disease. The present article reviews the role of imaging in the risk stratification of genetic DCM in general, with specific emphasis on DCM associated with neuromuscular disorders.

Evaluation of Left-Sided Heart Chambers With Novel Echocardiographic Techniques in Men With Duchenne or Becker Muscular Dystrophy

Left ventricular systolic dysfunction (LVSD) is a common finding in patients with Duchenne (DMD) and Becker (BMD) muscular dystrophies. Novel echocardiographic techniques have been used for the detection of LVSD in several heart diseases. We aim to compare cardiac anatomic and functional data studied by three-dimensional (3DE) and two-dimensional (2DE) echocardiography and to analyze the myocardial strain for the detection of early LVSD in DMD and BMD patients. We performed a cross-sectional study of 46 DMD and 14 BMD patients. We measured left atrium volume and left ventricle volumes and ejection fraction using 3DE and 2DE techniques. Myocardial strain analysis was derived from global longitudinal strain (GLS) measurements. GLS was measured by 2DE with the speckle tracking technique. The correlation between 3DE and 2DE for the measurement of left atrium volume as well as left ventricle diastolic and systolic volumes was strong. 2DE presented larger left atrium and left ventricle volumes. Left ventricle ejection fraction was similar between the two techniques. Myocardial strain analysis was able to detect early LVSD in 50.0% of DMD patients and in 9.1% of BMD patients. In conclusion, two-dimensional echocardiography appears to be a good alternative for the anatomical and functional evaluation of the left heart chambers in DMD and BMD patients. Myocardial strain analysis detects early LVSD in a sizable portion of patients with dystrophinopathies.

Speckle-Tracking Echocardiography in Children With Duchenne Muscular Dystrophy: A Prospective Multicenter Controlled Cross-Sectional Study

BACKGROUND

Prognosis of Duchenne muscular dystrophy (DMD) is related to cardiac dysfunction. Speckle-tracking echocardiographic (STE) imaging is emerging as a noninvasive functional biomarker to consider in the early detection of DMD-related cardiomyopathy. However, STE analysis has not been assessed in a prospectively controlled study, especially in presymptomatic children with DMD, and no study has used STE analysis in all three displacements (longitudinal, radial, and circumferential) and for both ventricles.

METHODS

This prospective controlled study enrolled 108 boys, 36 of whom had DMD (mean age, 11 ± 3.8 years) and 72 of whom were age-matched control subjects in a 1:2 case-control design. Conventional echocardiographic variables were collected for the left and right ventricles. STE analyses were performed in the longitudinal, radial, and circumferential displacements for the left ventricle and in the free wall longitudinal displacement for the right ventricle. The effect of age on the evolution of two-dimensional strain in children with DMD was studied by adding an interaction term, DMD × age, in the models.

RESULTS

Conventional echocardiographic measures were normal in both groups. Left ventricular (LV) ejection fraction ranged from 45% to 76% (mean, 63 ± 6%) in the DMD group and from 55% to 76% (mean, 64 ± 5%) in the control group. Global LV strain mean measures were significantly worse in the DMD group for the longitudinal (-16.8 ± 3.9% vs -20.6 ± 2.6%, P < .0001), radial (22.7 ± 11.3% vs 31.7 ± 14%, P = .002), and circumferential (-16.5 ± 3.8% vs -20.3 ± 3.1%, P < .0001) displacements. The decrease of global LV longitudinal strain with age in children with DMD was 0.34% per year more marked than that in control subjects. The LV inferolateral and anterolateral segments were specifically impaired, especially in the basal area. Right ventricular function evaluated using conventional echocardiography and STE analysis was normal and not different between children with DMD and control subjects.

CONCLUSIONS

The existence of altered LV strain despite normal LV function in children with DMD represents an important perspective for future pediatric drug trials in DMD-related cardiomyopathy prevention.

Ten Years of 2D Longitudinal Strain for Early Myocardial Dysfunction Detection: A Clinical Overview

In recent years, the role of left ventricular ejection fraction (EF) as the gold standard parameter for the evaluation of systolic function has been questioned, and many efforts have been concentrated in the clinical validation of new noninvasive tools for the study of myocardial contractility. Improvement in the accuracy of speckle-tracking echocardiography has resulted in a large amount of research showing the ability of two-dimensional strain to overcome EF limitations in the majority of primary and secondary heart diseases. Currently, global longitudinal strain (GLS) is considered the most accurate and sensitive parameter for the assessment of early left ventricular dysfunction. This review summarizes the advantages that this measurement can provide in several clinical settings. Moreover, the important cautions that should be considered in making the choice to use GLS also are addressed. Finally, a special focus on bull's-eye polar maps for the assessment of regional changes of longitudinal function and the usefulness of these maps in the differential diagnosis of several diseases is provided.

Evaluation of Early Left Ventricular Dysfunction in Patients with Duchenne Muscular Dystrophy Using Two-Dimensional Speckle Tracking Echocardiography and Tissue Doppler Imaging

Although progressive cardiac dysfunction is the leading cause of death in patients with Duchenne muscular dystrophy (DMD), their cardiac function measured by conventional echocardiography has been generally interpreted as normal at a young age. We aimed to determine whether two-dimensional speckle tracking echocardiography (STE) or tissue Doppler imaging (TDI) could be used for early identification and detection of cardiac dysfunction in young patients with DMD. Thirteen pediatric patients (mean age, 9.69 ± 2.2 years) with DMD and 26 age-matched healthy children (mean age, 9.65 ± 2.2 years) were included in the study. All patients were examined via conventional echocardiography, TDI, and STE. Standard echocardiographic measurements of left ventricular (LV) systolic and diastolic function were obtained. Myocardial velocities including peak-systolic and early- and late-diastolic myocardial velocities were calculated in longitudinal direction in the interventricular septum, using TDI. Speckle tracking analyses were performed by acquiring apical four-, three-, and two-chamber views with the highest possible frame rates. Conventional parameters were similar between the two groups, but heart rates were higher in patients with DMD than in controls. The results of LV diastolic function evaluated using TDI showed that annular peak velocity during early diastole (e'; 10.9 ± 1.7 vs. 14.6 ± 1.7 cm/s), e'/a' ratio (2.0 ± 0.5 vs. 3.0 ± 0.5), E/e' ratio (9.4 ± 1.4 vs. 7.3 ± 0.8), and myocardial performance index (0.46 ± 0.05 vs. 0.36 ± 0.06) of the mitral septal annulus among patients with DMD differed significantly from those of healthy children. A significant decrease in global longitudinal systolic strain was found in patients with DMD (- 16.6 ± 3.7 vs. - 21.2 ± 2.1), with a marked decrease in the LV basal inferolateral and basal inferior walls. In young patients with DMD who have global normal systolic function, reductions in systolic deformation parameters as well as reduced early diastolic myocardial velocities can be detected particularly in the basal inferolateral LV walls. The prognostic significance of these findings warrants further longitudinal follow-up.

Imaging the heart to detect cardiomyopathy in Duchenne muscular dystrophy: A review

Duchenne Muscular Dystrophy is the most common paediatric neuromuscular disorder. Mutations in the DMD gene on the X-chromosome result in progressive skeletal muscle weakness as the main clinical manifestation. However, cardiac muscle is also affected, with cardiomyopathy becoming an increasingly recognised cause of morbidity, and now the leading cause of mortality in this group. The diagnosis of cardiomyopathy has often been made late due to technical limitations in transthoracic echocardiograms and delayed symptomatology in less mobile patients. Increasingly, evidence supports earlier pharmacological intervention in cardiomyopathy to improve outcomes. However, the optimal timing of initiation remains uncertain, and the benefits of prophylactic therapy are unproven. Current treatment guidelines suggest initiation of therapy once cardiac dysfunction is detected. This review focuses on new and evolving techniques for earlier detection of Duchenne muscular dystrophy-associated cardiomyopathy. Transthoracic echocardiography or cardiac magnetic resonance imaging performed under physiological stress (dobutamine or exercise), can unmask early cardiac dysfunction. Cardiac magnetic resonance imaging can define cardiac function with greater accuracy and reliability than an echocardiogram, and is not limited by body habitus. Improved imaging techniques, used in a timely fashion, offer the potential for early detection of cardiomyopathy and improved long-term outcomes.

Myocardial Strain Using Cardiac MR Feature Tracking and Speckle Tracking Echocardiography in Duchenne Muscular Dystrophy Patients

Duchenne muscular dystrophy (DMD) is an inherited X-linked disorder with an incidence of 1 in 3500 male births, and cardiomyopathy is becoming the leading cause of death. While Cardiac MRI (CMR) and late gadolinium enhancement (LGE) are important tools in recognizing myocardial involvement, myocardial strain imaging may demonstrate early changes and allow patients to avoid gadolinium contrast. We performed CMR feature tracking (FT) and echo-based speckle tracking (STE) strain measures on DMD patients and age/sex matched controls who had received a CMR with contrast and transthoracic echocardiogram. Data were collected for longitudinal strain in the apical four-chamber view and circumferential strain in the mid-papillary parasternal short axis. Segmental wall analysis was performed and compared with the presence of LGE. Data were analyzed using student's t tests or one-way ANOVA adjusting for multiple comparisons. We measured 24 subjects with DMD and 8 controls. Thirteen of 24 DMD subjects were LGE positive only in the lateral segments in short-axis views. Average circumferential strain (CS) measured by FT was significantly decreased in DMD compared to controls (- 18.8 ± 6.1 vs. - 25.5 ± 3.2; p < 0.001) and showed significant differences in the anterolateral, inferolateral, and inferior segments. Average CS by STE trended towards significance (p = 0.06) but showed significance in only the inferior segment. FT showed significant differences in the inferolateral segment between LGE positive (- 15.5 ± 9.0) and LGE negative (- 18.2 ± 8.3) in DMD subjects compared to controls (- 28.6 ± 7.3; p ≤ 0.04). FT also showed significant differences between anteroseptal and inferolateral segments within LGE-positive (p < 0.003) and LGE-negative (p < 0.03) DMD subjects while STE did not. There were no significant differences in longitudinal strain measures. CMR-FT-derived myocardial strain was able to demonstrate differences between subjects with DMD and controls not detected by STE. FT was also able to demonstrate differences in LGE-positive and LGE-negative segments within patients with DMD. FT may be able to predict LGE-positive segments in DMD without the use of gadolinium contrast.

Predictors of early left ventricular systolic dysfunction in duchenne muscular dystrophy patients

INTRODUCTION

Early detection of left ventricular systolic dysfunction (LVSD) is important for therapeutic strategies for Duchenne muscular dystrophy (DMD) patients. We analyzed myocardial strain using echocardiography for early detection of LVSD and determined the predictors of early LVSD.

METHODS

This investigation was a cross-sectional study of 40 DMD patients with normal left ventricular ejection fraction. Global longitudinal strain (GLS) was used to analyze subtle disturbances in longitudinal contraction of the myocardium. Patients were determined to have early LVSD (GLS > -18) or normal left ventricular systolic function (GLS ≤ -18).

RESULTS

Patients who had early LVSD were older and had a higher frequency of corticosteroid therapy and of mutations in exons 45, 46, 47, 48, 49, 50, and 52.

DISCUSSION

Myocardial strain measurements are useful for the early diagnosis of LVSD in DMD patients. Older age, use of corticosteroids, and mutations within the "hot-spot" region of the DMD gene are associated with early LVSD. Muscle Nerve, 2018.