Left Ventricular End-Diastolic Diameter and Cardiac Mortality in Duchenne Muscular Dystrophy

Rate of Change in Cardiac Magnetic Resonance Imaging Measures Is Associated With Death in Duchenne Muscular Dystrophy

BACKGROUND

Cardiovascular disease is the leading cause of death among patients with Duchenne muscular dystrophy (DMD). Identifying patients at risk of early death could allow for increased monitoring and more intensive therapy. Measures that associate with death could serve as surrogate outcomes in clinical trials.

METHODS AND RESULTS

Duchenne muscular dystrophy subjects prospectively enrolled in observational studies were included. Models using generalized least squares were used to assess the difference of cardiac magnetic resonance measurements between deceased and alive subjects. A total of 63 participants underwent multiple cardiac magnetic resonance imaging and were included in the analyses. Twelve subjects (19.1%) died over a median follow-up of 5 years (interquartile range, 3.1-7.0). Rate of decline in left ventricular ejection fraction was faster in deceased than alive subjects (P<0.0001). Rate of increase in indexed left ventricular end-diastolic (P=0.0132) and systolic (P<0.0001) volumes were higher in deceased subjects. Faster worsening in midcircumferential strain was seen in deceased subjects (P=0.049) while no difference in global circumferential strain was seen. The rate of increase in late gadolinium enhancement, base T1, and mid T1 did not differ between groups.

CONCLUSIONS

Duchenne muscular dystrophy death is associated with the rate of change in left ventricular ejection fraction, midcircumferential strain, and ventricular volumes. Aggressive medical therapy to decrease the rate of progression may improve the mortality rate in this population. A decrease in the rate of progression may serve as a valid surrogate outcome for therapeutic trials.

Cardiovascular Measures of All-Cause Mortality in Duchenne Muscular Dystrophy

BACKGROUND

Cardiopulmonary failure is the leading cause of death in Duchenne muscular dystrophy (DMD). Research into DMD-specific cardiovascular therapies is ongoing, but there are no Food and Drug Administration-approved cardiac end points. To adequately power a therapeutic trial, appropriate end points must be chosen and the rate of change for these end points reported. The objective of this study was to evaluate rate of change for cardiac magnetic resonance and blood biomarkers and to determine which measures associate with all-cause mortality in DMD.

METHODS

Seventy-eight DMD subjects underwent 211 cardiac magnetic resonance studies analyzed for left ventricular (LV) ejection fraction, indexed LV end diastolic and systolic volumes, circumferential strain, late gadolinium enhancement presence and severity (global severity score, and full width half maximum), native T1 mapping, T2 mapping, and extracellular volume. Blood samples were analyzed for BNP (brain natriuretic peptide), NT-proBNP (N-terminal pro-B-type natriuretic peptide), and troponin I. Cox proportional hazard regression modeling was performed with all-cause mortality as the outcome.

RESULTS

Fifteen subjects (19%) died. LV ejection fraction, indexed end systolic volumes, global severity score, and full width half maximum worsened at 1 and 2 years while circumferential strain and indexed LV end diastolic volumes worsened at 2 years. LV ejection fraction, indexed LV end diastolic and systolic volumes, late gadolinium enhancement full width half maximum, and circumferential strain associated with all-cause mortality (P<0.05). NT-proBNP was the only blood biomarker that associated with all-cause mortality (P<0.05).

CONCLUSIONS

LV ejection fraction, indexed LV volumes, circumferential strain, late gadolinium enhancement full width half maximum, and NT-proBNP are associated with all-cause mortality in DMD and may be the best end points for use in cardiovascular therapeutic trials. We also report change over time of cardiac magnetic resonance and blood biomarkers.

Prognostic factors, disease course, and treatment efficacy in Duchenne muscular dystrophy: A systematic review and meta-analysis

INTRODUCTION/AIMS

Prognostic factors in Duchenne muscular dystrophy (DMD) predict the disease course and may help individualize patient care. The aim was to summarize the evidence on prognostic factors that may support treatment decisions.

METHODS

We searched six databases for prospective studies that each included ≥50 DMD patients with a minimum follow-up of 1 y. Primary outcomes were age at loss of ambulation (LoA), pulmonary function (forced vital capacity percent of predicted, FVC%p), and heart failure.

RESULTS

Out of 5074 references, 59 studies were analyzed. Corticosteroid use was associated with a delayed LoA (pooled effect hazard ratio [HR] 0.42, 95% confidence interval [CI] 0.23-0.75, I2 94%), better pulmonary function tests (higher peak FVC%, prolonged time with FVC%p > 50%, and reduced need for assisted ventilation) and delayed cardiomyopathy. Longer corticosteroid treatment was associated with later LoA (>1 y compared to <1 y; pooled HR: 0.50, 95% CI 0.27-0.90) and early treatment start (aged <5 y) may be associated with early cardiomyopathy and higher fracture risk. Genotype appeared to be an independent driver of LoA in some studies. Higher baseline physical function tests (e.g., 6-minute walk test) were associated with delayed LoA. Left ventricular dysfunction and FVC <1 L increased and the use of angiotensin-converting enzyme (ACE) inhibitors reduced the risk of heart failure and death. Fusion surgery in scoliosis may potentially preserve pulmonary function.

DISCUSSION

Prognostic factors that may inform clinical decisions include age at corticosteroid treatment initiation and treatment duration, ACE-inhibitor use, baseline physical function tests, pulmonary function, and cardiac dysfunction.

Prognostic factors associated with left ventricular non-compaction: A PRISMA-compliant meta-analysis

BACKGROUND

Left ventricular non-compaction (LVNC) is a rare disease with a poor prognosis. Efforts to improve prognosis are limited by the quality and scope of the available evidence on prognostic factors.

METHODS

Pubmed, Embase, China National Knowledge Infrastructure, Cochrane Library, Wanfang, and Baidu Scholar were searched and all relevant studies that examined factors related to LVNC prognosis, published before January 2021, were retrieved. Study quality evaluation and data extraction were independently completed by two authors. Statistical analyses were performed using STATA 15.0 software.

RESULTS

A total of 20 cohort studies were included in this study, with a total of 1910 patients. The results of the meta-analysis are as follows: New York Heart Function Association (NYHA) class III/IV (hazard ratio [HR] = 3.93, 95% confidence interval [CI]: 1.66-9.29), (NT-proBNP) increased (HR = 1.98, 95% CI: 1.10-3.58), left ventricular ejection fraction (LVEF) decreased (HR = 1.04, 95% CI: 1.03-1.06), left ventricular end-diastolic diameter (LVEDD) increased (HR = 1.03, 95% CI: 1.01-1.06) was an independent poor prognostic factor, and body mass index (HR = 0.80, 95% CI: 0.64-0.98) was an independent protective factor. Creatinine (CR) level (HR = 1.09, 95% CI: 0.95-1.25) and late gadolinium-enhanced (LGE) imaging (HR = 3.1, 95% CI: 0.85-11.31) has no statistical significance in the prognosis of LVNC.

CONCLUSION

In LVNC patients, NYHA class III/IV, elevated N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, decreased LVEF, and increased LVEDD may lead to poor prognosis, and increased body mass index may improve the prognosis of LVNC. Further clinical research with large sample sizes and long-term follow-ups should be conducted.

PROSPERO REGISTRATION NUMBER

42020152706.

Sunitinib inhibits STAT3 phosphorylation in cardiac muscle and prevents cardiomyopathy in the mdx mouse model of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a fatal X-linked genetic disorder affecting approximately 1 in 5000 male births worldwide. DMD is caused by mutations in the dystrophin gene. Dystrophin is essential for maintaining muscle cell membrane integrity and stability by linking the cytoskeleton to the extracellular matrix, which protects myofibers from contraction-induced damage. Loss of dystrophin leads to mechanically induced skeletal and cardiac muscle damage. Although the disease is not evident in DMD patients at birth, muscular dystrophy rapidly progresses and results in respiratory and cardiac muscle failure as early as the teenage years. Premature death in DMD patients is due to cardiac arrhythmias and left ventricular dysfunction. Currently, there is no effective treatment for DMD-related cardiac failure. Recently, we have shown that a Food and Drug Administration-approved small molecule, sunitinib, a multi-targeted tyrosine kinase inhibitor can mitigate skeletal muscle disease through an increase in myogenic capacity, cell membrane integrity, and improvement of skeletal muscle function via regulation of STAT3-related signaling pathway. Chronic activation of STAT3 has been shown to promote cardiac hypertrophy and failure. In this study, we examined the effects of long-term sunitinib treatment on cardiac pathology and function. Our results showed sunitinib treatment reduced STAT3 phosphorylation in the heart muscle of mdx mice, improved cardiac electrical function, increased cardiac output and stroke volume, decreased ventricular hypertrophy, reduced cardiomyocytes membrane damage, fibrotic tissue deposition and slightly decreased cardiac inflammation. Together, our studies support the idea that sunitinib could serve as a novel treatment to slow cardiomyopathy progression in DMD. One Sentence Summary In this study, we determined if sunitinib, a Food and Drug Administration-approved drug, could reduce the pathology and improve cardiac function in an animal model for DMD.

Artificial Intelligence-Enabled Electrocardiogram Predicted Left Ventricle Diameter as an Independent Risk Factor of Long-Term Cardiovascular Outcome in Patients With Normal Ejection Fraction

Background

Heart failure (HF) is a global disease with increasing prevalence in an aging society. However, the survival rate is poor despite the patient receiving standard treatment. Early identification of patients with a high risk of HF is important but challenging. Left ventricular end-diastolic diameter (LV-D) increase was an independent risk factor of HF and adverse cardiovascular (CV) outcomes. In this study, we aimed to develop an artificial intelligence (AI) enabled electrocardiogram (ECG) system to detect LV-D increase early.

Objective

We developed a deep learning model (DLM) to predict left ventricular end-diastolic and end-systolic diameter (LV-D and LV-S) with internal and external validations and investigated the relationship between ECG-LV-D and echocardiographic LV-D and explored the contributions of ECG-LV-D on future CV outcomes.

Methods

Electrocardiograms and corresponding echocardiography data within 7 days were collected and paired for DLM training with 99,692 ECGs in the development set and 20,197 ECGs in the tuning set. The other 7,551 and 11,644 ECGs were collected from two different hospitals to validate the DLM performance in internal and external validation sets. We analyzed the association and prediction ability of ECG-LVD for CV outcomes, including left ventricular (LV) dysfunction, CV mortality, acute myocardial infarction (AMI), and coronary artery disease (CAD).

Results

The mean absolute errors (MAE) of ECG-LV-D were 5.25/5.29, and the area under the receiver operating characteristic (ROC) curves (AUCs) were 0.8297/0.8072 and 0.9295/0.9148 for the detection of mild (56 ≦ LV-D < 65 mm) and severe (LV-D ≧ 65 mm) LV-D dilation in internal/external validation sets, respectively. Patients with normal ejection fraction (EF) who were identified as high ECHO-LV-D had the higher hazard ratios (HRs) of developing new onset LV dysfunction [HR: 2.34, 95% conference interval (CI): 1.78–3.08], CV mortality (HR 2.30, 95% CI 1.05–5.05), new-onset AMI (HR 2.12, 95% CI 1.36–3.29), and CAD (HR 1.59, 95% CI 1.26–2.00) in the internal validation set. In addition, the ECG-LV-D presents a 1.88-fold risk (95% CI 1.47–2.39) on new-onset LV dysfunction in the external validation set.

Conclusion

The ECG-LV-D not only identifies high-risk patients with normal EF but also serves as an independent risk factor of long-term CV outcomes.

Metformin Reverses the Enhanced Myocardial SR/ER-Mitochondria Interaction and Impaired Complex I-Driven Respiration in Dystrophin-Deficient Mice

Besides skeletal muscle dysfunction, Duchenne muscular dystrophy (DMD) exhibits a progressive cardiomyopathy characterized by an impaired calcium (Ca²⁺) homeostasis and a mitochondrial dysfunction. Here we aimed to determine whether sarco-endoplasmic reticulum (SR/ER)–mitochondria interactions and mitochondrial function were impaired in dystrophic heart at the early stage of the pathology. For this purpose, ventricular cardiomyocytes and mitochondria were isolated from 3-month-old dystrophin-deficient mice (mdx mice). The number of contacts points between the SR/ER Ca²⁺ release channels (IP3R1) and the porine of the outer membrane of the mitochondria, VDAC1, measured using in situ proximity ligation assay, was greater in mdx cardiomyocytes. Expression levels of IP3R1 as well as the mitochondrial Ca²⁺ uniporter (MCU) and its regulated subunit, MICU1, were also increased in mdx heart. MICU2 expression was however unchanged. Furthermore, the mitochondrial Ca²⁺ uptake kinetics and the mitochondrial Ca²⁺ content were significantly increased. Meanwhile, the Ca²⁺-dependent pyruvate dehydrogenase phosphorylation was reduced, and its activity significantly increased. In Ca²⁺-free conditions, pyruvate-driven complex I respiration was decreased whereas in the presence of Ca²⁺, complex I-mediated respiration was boosted. Further, impaired complex I-mediated respiration was independent of its intrinsic activity or expression, which remains unchanged but is accompanied by an increase in mitochondrial reactive oxygen species production. Finally, mdx mice were treated with the complex I modulator metformin for 1 month. Metformin normalized the SR/ER-mitochondria interaction, decreased MICU1 expression and mitochondrial Ca²⁺ content, and enhanced complex I-driven respiration. In summary, before any sign of dilated cardiomyopathy, the DMD heart displays an aberrant SR/ER-mitochondria coupling with an increase mitochondrial Ca²⁺ homeostasis and a complex I dysfunction. Such remodeling could be reversed by metformin providing a novel therapeutic perspective in DMD.