107th ENMC international workshop: the management of cardiac involvement in muscular dystrophy and myotonic dystrophy. 7th-9th June 2002, Naarden, the Netherlands

Creatine Kinase-MM/Proto-oncogene Tyrosine-Protein Kinase Receptor as a Sensitive Indicator for Duchenne Muscular Dystrophy Carriers

Duchenne muscular dystrophy (DMD), a lethal X-linked recessive genetic disease, is characterized by progressive muscle wasting which will lead to premature death by cardiorespiratory complications in their late twenties. And 2.5-19% DMD carriers that also suffer from skeletal muscle damage or dilated cardiomyopathy when diagnosed as soon as possible is meaningful for prenatal diagnosis and advance warning for self-health. The current DMD carrier screening mainly relies on detecting serum creatine kinase activity, covering only 50-70% DMD carriers which will cause many false negatives and require the discovery of highly effective biomarker and simple detection procedure for DMD carriers. In this article, we have compiled a comprehensive summary of all documented biomarkers associated with DMD and categorized them based on their expression patterns. We specifically pinpointed novel DMD biomarkers, previously unreported in DMD carriers, and conducted further investigations to explore their potential. Compared to creatine kinase activity alone in DMD carriers, creatine kinase-MM can improve the specificity from 73 to 81%. And our investigation revealed another promising protein: proto-oncogene tyrosine-protein kinase receptor (RET). When combined with creatine kinase-MM (creatine kinase-MM/RET ratio), it significantly enhances the specificity (from 81 to 83%) and sensitivity (from 71.4 to 93%) of detecting DMD carriers in serum. Moreover, we successfully devised an efficient method for extracting RET from dried blood spots. This breakthrough allowed us to detect both creatine kinase-MM and RET using dried blood spots without compromising the detection rate.

Caregiver Burden with Duchenne and Becker Muscular Dystrophy in Japan: A Clinical Observation Study

Objective Skeletal muscle weakness and cardiomyopathy can be seen in carriers of dystrophinopathy. Therefore, the health management of caregivers of Duchenne/Becker muscular dystrophy (DMD/BMD) patients who are themselves carriers is an important issue. However, few studies have focused on caregivers who have dystrophin mutations. Methods In this cross-sectional study conducted at five hospitals, the daily living, situation medical treatment status, genetic testing, physical assessment, care burden, and quality of life of caregivers of DMD/BMD patients were surveyed. Results The subjects were 36 main caregivers (mean age 55.7±8.4 years old), of whom 52.8% were diagnosed as carriers, 8.3% were noncarriers, and 38.9% were not confirmed. In addition, half of the caregivers were not examined regularly at medical institutions. Of all caregivers, 54.3% had muscle or cardiac symptoms, and 75% had elevated serum creatine kinase levels. The mean Zarit Caregiver Burden Interview (ZBI) total score of current caregivers was 20.9±13.1. The frequency of a ZBI total score ≥25 was significantly higher in caregivers diagnosed as carriers than in caregivers unexamined as carriers (p=0.04). The health-related quality of life score (Short Form 36; SF-36) in caregivers was slightly lower than the Japanese standard scores in the sections of physical functioning, role limitations-physical, bodily pain, and social functioning. Conclusion Some caregivers of DMD/BMD patients can themselves have muscular or cardiac symptoms and a heavy care burden. It is therefore necessary for carrier caregivers, especially women, to undergo regular health checkups and receive appropriate health management.

Phenotypic features of genetically modified DMD-XKOXWT pigs

Introduction

Duchenne muscular dystrophy (DMD) is a hereditary neuromuscular disorder caused by mutation in the dystrophin gene (DMD) on the X chromosome. Female DMD carriers occasionally exhibit symptoms such as muscle weakness and heart failure. Here, we investigated the characteristics and representativeness of female DMD carrier (DMD-XKOXWT) pigs as a suitable disease model.

Methods

In vitro fertilization using sperm from a DMD-XKOY↔XWTXWT chimeric boar yielded DMD-XKOXWT females, which were used to generate F2 and F3 progeny, including DMD-XKOXWT females. F1-F3 piglets were genotyped and subjected to biochemical analysis for blood creatine kinase (CK), aspartate aminotransferase, and lactate dehydrogenase. Skeletal muscle and myocardial tissue were analyzed for the expression of dystrophin and utrophin, as well as for lymphocyte and macrophage infiltration.

Results

DMD-XKOXWT pigs exhibited various characteristics common to human DMD carrier patients, namely, asymptomatic hyperCKemia, dystrophin expression patterns in the skeletal and cardiac muscles, histopathological features of skeletal muscle degeneration, myocardial lesions in adulthood, and sporadic death. Pathological abnormalities observed in the skeletal muscles in DMD-XKOXWT pigs point to a frequent incidence of pathological abnormalities in the musculoskeletal tissues of latent DMD carriers. Our findings suggest a higher risk of myocardial abnormalities in DMD carrier women than previously believed.

Conclusions

We demonstrated that DMD-XKOXWT pigs could serve as a suitable large animal model for understanding the pathogenic mechanism in DMD carriers and developing therapies for female DMD carriers.

Clinical features, imaging findings and molecular data of limb-girdle muscular dystrophies in a cohort of Chinese patients

BACKGROUND

Limb-girdle muscular dystrophies (LGMDs) are a group of heterogeneous inherited diseases predominantly characterized by limb-girdle muscle weakness and dystrophic changes on histological analysis. The frequency of LGMD subtypes varies among regions in China and ethnic populations worldwide. Here, we analyzed the prevalence of LGMD subtypes, their corresponding clinical manifestations, and molecular data in a cohort of LGMD patients in Southeast China.

METHODS

A total of 81 consecutive patients with clinically suspected LGMDs from 62 unrelated families across Southeast China were recruited for targeted next-generation sequencing and whole-exome sequencing from July 2017 to February 2020.

RESULTS

Among 50 patients (41 families) with LGMDs, the most common subtypes were LGMD-R2/LGMD2B (36.6%) and LGMD-R1/LGMD2A (29.3%). Dystroglycanopathies (including LGMD-R9/LGMD2I, LGMD-R11/LGMD2K, LGMD-R14/LGMD2N and LGMD-R20/LGMD2U) were the most common childhood-onset subtypes and were found in 12.2% of the families. A total of 14.6% of the families had the LGMD-R7/LGMD2G subtype, and the mutation c.26_33dupAGGTGTCG in TCAP was the most frequent (83.3%). The only patient with the rare subtype LGMD-R18/LGMD2S had TRAPPC11 mutations; had a later onset than those previously reported, and presented with proximal‒distal muscle weakness, walking aid dependency, fatty liver disease and diabetes at 33 years of age. A total of 22.0% of the patients had cardiac abnormalities, and one patient with LMNA-related muscular dystrophy/LGMD1B experienced sudden cardiac death at 37 years of age. A total of 15.4% of the patients had restrictive respiratory insufficiency. Muscle imaging in patients with LGMD-R1/LGMD2A and LGMD-R2/LGMD2B showed subtle differences, including more severe fatty infiltration of the posterior thigh muscles in those with LGMD-R1/LGMD2A and edema in the lower leg muscles in those with LGMD-R2/LGMD2B.

CONCLUSION

We determined the prevalence of different LGMD subtypes in Southeast China, described the detailed clinical manifestations and distinct muscle MRI patterns of these LGMD subtypes and reported the frequent mutations and the cardiorespiratory involvement frequency in our cohort, all of which might facilitate the differential diagnosis of LGMDs, allowing more timely treatment and guiding future clinical trials.

The role of fibrosis in the pathophysiology of muscular dystrophy

Muscular dystrophy exerts significant and dramatic impacts on affected patients, including progressive muscle wasting leading to lung and heart failure, and results in severely curtailed lifespan. Although the focus for many years has been on the dysfunction induced by the loss of function of dystrophin or related components of the striated muscle costamere, recent studies have demonstrated that accompanying pathologies, particularly muscle fibrosis, also contribute adversely to patient outcomes. A significant body of research has now shown that therapeutically targeting these accompanying pathologies via their underlying molecular mechanisms may provide novel approaches to patient management that can complement the current standard of care. In this review, we discuss the interplay between muscle fibrosis and muscular dystrophy pathology. A better understanding of these processes will contribute to improved patient care options, restoration of muscle function, and reduced patient morbidity and mortality.

Diagnosis and management of Becker muscular dystrophy: the French guidelines

Becker muscular dystrophy (BMD) is one of the most frequent among neuromuscular diseases, affecting approximately 1 in 18,000 male births. It is linked to a genetic mutation on the X chromosome. In contrast to Duchenne muscular dystrophy, for which improved care and management have changed the prognosis and life expectancy of patients, few guidelines have been published for management of BMD. Many clinicians are inexperienced in managing the complications of this disease. In France, a committee of experts from a wide range of disciplines met in 2019 to establish recommendations, with the goal of improving care of patients with BMD. Here, we present the tools to provide diagnosis of BMD as quickly as possible and for differential diagnoses. Then, we describe the multidisciplinary approach essential for optimum management of BMD. We give recommendations for the initial assessment and follow-up of the neurological, respiratory, cardiac, and orthopedic consequences of males who present with BMD. Finally, we describe the optimal therapeutic management of these complications. We also provide guidance on cardiac management for female carriers.

Cardiomyopathy as cause of death in Duchenne muscular dystrophy: a longitudinal observational study

Background

Cardiomyopathy has become an important life-limiting factor since survival in Duchenne muscular dystrophy (DMD) has greatly increased with long-term ventilation and cough assistance. The aim of this study was to investigate the association between impaired left ventricular ejection fraction (LVEF) and survival.

Methods

In a >20-year observational study in patients with DMD (age ≥16 years) with at least three echocardiograms, the association between LVEF and survival and time to cardiac or non-cardiac death was investigated using Kaplan-Meier survival analysis and Cox regression (for LVEF).

Results

In 67 DMD patients (430 echocardiograms), the decrease in LVEF over a mean±sd follow-up period of 9.1±5.1 years was -10.0±13.9% absolute, but LVEF progression varied widely. 84% were receiving an angiotensin-converting enzyme inhibitor and 54% a β-blocker at last follow-up with an LVEF of 37.5±12.4% at that time-point. Median (interquartile range) survival was 33 (25-40) years. 28 out of 67 (42%) of the cohort had died and LVEF was a significant negative predictor of survival (hazard ratio 0.95 (95% CI 0.91-0.99); p<0.007). Those who died of cardiac death (53% of known causes of death) had significantly lower LVEF at the time of death (LVEF -11.0% (95% CI -21.1- -0.9%); p=0.035) compared with non-cardiac death and tended to die at a younger age.

Conclusions

Cardiomyopathy with systolic heart failure is the leading cause of death and lower LVEF is an independent predictor of mortality at younger ages in patients with DMD. Patients with DMD appear to be undertreated with respect to heart failure drug therapy.

Incidence of Duchenne muscular dystrophy in the modern era; an Australian study

Duchenne muscular dystrophy (DMD), an X-linked recessive condition is maternally inherited in two-thirds of affected boys. It is important to establish carrier status of female relatives to restore reproductive confidence for non-carriers and facilitate reproductive options and cardiac surveillance for carriers. This study investigates disease incidence within an Australian model of cascade screening and evolving genetic diagnostic technologies. A retrospective population-based cohort study of all genetically and/or histopathologically confirmed males with DMD, born in New South Wales and the Australian Capital Territory was undertaken from 2002-2012. Cases were identified using state-wide molecular laboratory and clinical databases. The annual disease incidence and "theoretically" preventable cases were extrapolated over the study period. Proband genotype/phenotype, pedigree analysis, carrier-risk and extent of cascade screening were also determined. The cumulative incidence of disease was 19.7 per 100,000 male live births and 1 in 5076 live born males were diagnosed with DMD. Differences in disease incidence were not statistically different when compared between 2002-2007 and 2008-2012 (incidence rate ratio = 1.13, 95% CI 0.76-1.69, p = 0.52). The incidence rate ratio of theoretically preventable cases did not significantly change between 2002-2007 and 2008-2012 (incidence rate ratio = 2.07, 95% CI 0.58-9.21, p = 0.23). Current diagnostic and cascade screening models have limitations in their impact on disease incidence, due to a spectrum of logistical, patient and condition related factors. Innovative approaches to reduce DMD incidence may be better achieved by preconception or early pregnancy carrier screening, prenatal exome sequencing and newborn screening.

Clinical outcomes of continuous flow left ventricular assist device therapy as bridge to transplant strategy in muscular dystrophy: a single-center study

OBJECTIVE

In muscular dystrophies (MD) patients with end-stage heart failure (HF), continuous flow left ventricular assist device (cf-LVAD) therapy is still controversial due to a progressive nature of MD-associated muscle weakness.

METHODS

All the MD patients who had cf- VAD implants between March 2013 and August 2019 in our hospital were retrospectively studied. Study end points were death, major LVAD-associated complications or respiratory dysfunction caused by muscular weakness.

RESULTS

A total of 11 MD patients (Becker type: n = 6; Emery-Dreifuss Myodystrophy: n = 2; Fukuyama subtype: n = 1; Limb-girdle 1B: n = 2) were enrolled.

DEMOGRAPHICS

median age 41 years (IQR; 29-47); median Japanese Registry for Mechanically Assisted Circulatory Support: level 3 (2-3); a median interval between MD diagnosis and LVAD implantation 9 years (6-18). The pulmonary function test at LVAD implantation showed a median of %VC; 62% (45-82), FEV_1%, 82% (81-88). Survival to discharge was 100% without pulmonary complication and early VAD-related complications. During a median follow-up of 38 months (27-53), re-admissions were needed due to device infection (n = 2), cerebrovascular accidents (disabling, n = 2 and non-disabling, n = 2), ventricular tachycardia (n = 4), and right HF (n = 3), respectively. 7 patients received successful heart transplant after a median waiting time of 44 months (34-61); 3 patients are still on the waiting list (waiting time: 21, 38, and 39 months). One patient died of right HF 15 months after VAD implantation. No one had overt pulmonary dysfunction during LVAD support.

CONCLUSION

In selected MD patients with end-stage HF, cf-LVAD therapy is a viable therapeutic option as bridge to heart transplant.

Prevention of Adverse Outcomes and Treatment Side Effects in Patients with Neuromuscular Disorders

In this article, we review prevention of serious adverse clinical outcomes and treatment side effects in patients with neuromuscular disorders including myopathies and myasthenia gravis. While neither of these entities is preventable, their course can often be modified, and severe sequelae may be prevented, with the identification of risk factors and proactive attention toward treatment planning.

Cardiac care of children with dystrophinopathy and females carrying DMD-gene variations

OBJECTIVE

We provide succinct, evidence-based and/or consensus-based best practice guidance for the cardiac care of children living with Duchenne muscular dystrophy (DMD) as well as recommendations for screening and management of female carriers of mutations in the DMD-gene.

METHODS

Initiated by an expert working group of UK-based cardiologists, neuromuscular clinicians and DMD-patient representatives, draft guidelines were created based on published evidence, current practice and expert opinion. After wider consultation with UK-cardiologists, consensus was reached on these best-practice recommendations for cardiac care in DMD.

RESULTS

The resulting recommendations are presented in the form of a succinct care pathway flow chart with brief justification. The guidance signposts evidence on which they are based and acknowledges where there have been differences in opinion. Guidelines for cardiac care of patients with more advanced cardiac dystrophinopathy at any age have also been considered, based on the previous published work of Quinlivan et al and are presented here in a similar format. The recommendations have been endorsed by the British Cardiovascular Society.

CONCLUSION

These guidelines provide succinct, reasoned recommendations for all those managing paediatric patients with early or advanced stages of cardiomyopathy as well as females with cardiac dystrophinopathy. The hope is that this will result in more uniform delivery of high standards of care for children with cardiac dystrophinopathy, so improving heart health into adulthood through timely earlier interventions across the UK.

Neuromuscular diseases and their cardiac manifestations under the spectrum of cardiovascular imaging

Neuromuscular diseases (NMDs) include a broad spectrum of disorders that affect motor unit in every possible site, extending from the cell body of peripheral nerves to the muscle. The different lesion sites make this group of inherited disorders difficult to diagnose. Many NMDs, especially those involving skeletal muscles, can present significant cardiovascular complications, ranging from rhythm disturbances to the development of dilated or hypertrophic cardiomyopathy. Heart disease represents a major cause of morbidity and mortality among NMD patients, underlining the vital need for further familiarization with the pathogenesis and assessment of cardiac involvement. Cardiovascular imaging is the cornerstone for the evaluation of heart disorders in NMDs, with conventional echocardiography still offering a portable, affordable, and easily accessible solution. Meanwhile, newer echocardiographic techniques such as speckle tracking imaging in combination with cardiac magnetic resonance add new insights into further substrate characterization. The purpose of this review is to offer a brief presentation of the main NMDs and their cardiovascular complications, as well as the presentation of data that highlight the importance of cardiovascular imaging in early diagnosis, monitoring, and prognosis of these patients. Lastly, the authors provide a simple guide about which clinical features, imaging findings, and follow-up plan to adopt in each myopathic disorder.

Advanced Gene-Targeting Therapies for Motor Neuron Diseases and Muscular Dystrophies

Gene therapy is a revolutionary, cutting-edge approach to permanently ameliorate or amend many neuromuscular diseases by targeting their genetic origins. Motor neuron diseases and muscular dystrophies, whose genetic causes are well known, are the frontiers of this research revolution. Several genetic treatments, with diverse mechanisms of action and delivery methods, have been approved during the past decade and have demonstrated remarkable results. However, despite the high number of genetic treatments studied preclinically, those that have been advanced to clinical trials are significantly fewer. The most clinically advanced treatments include adeno-associated virus gene replacement therapy, antisense oligonucleotides, and RNA interference. This review provides a comprehensive overview of the advanced gene therapies for motor neuron diseases (i.e., amyotrophic lateral sclerosis and spinal muscular atrophy) and muscular dystrophies (i.e., Duchenne muscular dystrophy, limb-girdle muscular dystrophy, and myotonic dystrophy) tested in clinical trials. Emphasis has been placed on those methods that are a few steps away from their authoritative approval.

Involvement of muscle satellite cell dysfunction in neuromuscular disorders: Expanding the portfolio of satellite cell-opathies

Neuromuscular disorders are a heterogeneous group of acquired or hereditary conditions that affect striated muscle function. The resulting decrease in muscle strength and motility irreversibly impacts quality of life. In addition to directly affecting skeletal muscle, pathogenesis can also arise from dysfunctional crosstalk between nerves and muscles, and may include cardiac impairment. Muscular weakness is often progressive and paralleled by continuous decline in the ability of skeletal muscle to functionally adapt and regenerate. Normally, the skeletal muscle resident stem cells, named satellite cells, ensure tissue homeostasis by providing myoblasts for growth, maintenance, repair and regeneration. We recently defined 'Satellite Cell-opathies' as those inherited neuromuscular conditions presenting satellite cell dysfunction in muscular dystrophies and myopathies (doi:10.1016/j.yexcr.2021.112906). Here, we expand the portfolio of Satellite Cell-opathies by evaluating the potential impairment of satellite cell function across all 16 categories of neuromuscular disorders, including those with mainly neurogenic and cardiac involvement. We explore the expression dynamics of myopathogenes, genes whose mutation leads to skeletal muscle pathogenesis, using transcriptomic analysis. This revealed that 45% of myopathogenes are differentially expressed during early satellite cell activation (0 - 5 hours). Of these 271 myopathogenes, 83 respond to Pax7, a master regulator of satellite cells. Our analysis suggests possible perturbation of satellite cell function in many neuromuscular disorders across all categories, including those where skeletal muscle pathology is not predominant. This characterisation further aids understanding of pathomechanisms and informs on development of prognostic and diagnostic tools, and ultimately, new therapeutics.

Anti-Remodeling Cardiac Therapy in Patients With Duchenne Muscular Dystrophy, Meta-Analysis Study

Background: Almost all Duchenne muscular dystrophy (DMD) patients that reach their 30s present cardiomyopathy. As a result, this population remains under-treated. There is no sufficient proof of the efficacy of anti-remodeling cardiac therapy for DMD cardiomyopathy (DMDCM). We aim to assess the efficacy of anti-remodeling cardiac therapy for DMDCM by using meta-analysis.

Methods: PubMed (MEDLINE), Embase, and Cochrane library were searched through January 2021. Randomized control trials, case-control studies, and observational studies that reported assessments of cardiovascular outcomes and death of participants using angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, mineralocorticoid-receptor antagonists and Ivabradine, were included. The primary outcome was total mortality. Secondary outcomes included changes in left ventricular ejection fraction (LVEF), serum natriuretic peptide levels (BNP), and heart rate (HR). Data were extracted for eligibility by two independent reviewers. Random-effects meta-analysis was used to pool results.

Results: Twelve studies with 439 patients were included in our meta-analysis. Treated patients have lower HR, mean difference of −17 beats per minute (CI [−25]–[−9], p < 0.01). The LVEF was improved in treated patients, with a mean difference of LVEF of 3.77% (CI 0.44–7.12, p < 0.03). Although mortality rates did not reach statistical significance there was a trend for total mortality reduction (hazard ratio 0.36, CI (0.1–1.25), p = 0.107) and for BNP reduction (SSMD: 0.141, CI ([−0.19]–[0.47]), p = 0.3).

Conclusion: Pharmacologic treatment for DMDCM patients is associated with decreased HR and improved LVEF. Therefore, DMDCM patients may benefit from implementing guideline therapy for HF.

Degenerative disease-on-a-chip: Developing microfluidic models for rapid availability of newer therapies

BACKGROUND

Understanding the pathophysiology of degenerative diseases pertaining to nervous system, ocular region, bone/cartilage and muscle are still being comprehended, thus delaying the availability of targeted therapies.

PURPOSE AND SCOPE

Newer micro-physiological systems (organ-on-chip technology) involves development of more sophisticated devices, modelling a range of in vitro human tissues and an array of models for diseased conditions. These models expand opportunities for high throughput screening (HTS) of drugs and are likely to be rapid and cost-effective, thus reducing extensive usage of animal models.

CONCLUSION

Through this review article, we aim to present an overview of the degenerative disease models that are presently being developed using microfluidic platforms with the aim of mimicking in vivo tissue physiology and micro-architecture. The manuscript provides an overview of the degenerative disease models and their potential for testing and screening of possible biotherapeutic molecules and drugs. It highlights the perspective of the regulatory bodies with respect to the established-on chip models and thereby enhancing its translational potential. This article is protected by copyright. All rights reserved.

Effects of cardiac medications on ventricular function in patients with Duchenne muscular dystrophy-related cardiomyopathy

INTRODUCTION/AIMS

The DMD Care Considerations Working Group Guidelines 2010 recommended treating cardiac dystrophinopathy with angiotensin-converting enzyme-inhibitor (ACEi) and beta-blocker (BB) therapy to prevent the progressive decline in left ventricular function expected from earlier, natural history studies. The aim of this research was to audit change in measures of left ventricular function over 8 years to 4 years before and 4 years after deploying an ACEi/BB combination systematically at a dedicated "cardiology-muscle" clinic.

METHODS

This is an institutionally registered, retrospective, case-file-based audit of serial echocardiographic measures of left ventricular fractional shortening accumulated over the period 1995 to 2015.

RESULTS

Data from 104 genetically confirmed Duchenne muscular dystrophy (DMD) patients, aged 22.2 ± 5.3 years at data censure, were included. Mean age at first detection of left ventricular dysfunction was 15.1 ± 4.2 years, but older in those on maintenance steroid therapy (16.8 ± 4.2 vs 14.5 ± 4.1 years; P = .04). Group mean fractional shortening fell by 1.5%/year over the 4 years before therapy, but this decreased to 0.9%/year over the first 4 years after starting therapy. Analysis of limited left ventricular ejection fraction measures showed similar but nonsignificant changes. Neither age at detection of left ventricular dysfunction nor fractional shortening percent at time of therapy initiation affected the beneficial response.

DISCUSSION

The results support the international DMD recommendations of the time. This combination of cardiac medications helps stabilize heart function. For the best long-term effects, therapy needs to be initiated no later than on first detection left ventricular impairment.

Respiratory decline in adult patients with Becker muscular dystrophy: A longitudinal study

Becker muscular dystrophy (BMD) is a rare hereditary neuromuscular disease, caused by a genetic defect in the Duchenne Muscular Dystrophy (DMD) gene. We studied the natural history of respiratory function and its affecting factors in 23 adult BMD patients. These important data are needed for (future) clinical trials in BMD but are largely lacking. Patients had a median age of 51 years (28-78y) and median follow-up duration of 14 years (2-25y). We analysed 190 pulmonary function measurements with a median interval of one year (1-17y) and measured a 1.00% decline of Forced Vital Capacity percent predicted (FVC%pred) per year (p = 0.004). Loss of ambulation significantly increased the annual rate of FVC decline and was dependent of patient's body mass index (BMI; p = 0.015), with increases in BMI correlating with an even more rapid deterioration of FVC. A decline in Medical Research Council (MRC) sum score was significantly correlated with a decline in FVC (p = 0.003). We conclude that adult BMD patients experience a significant but mild respiratory decline. However, this decline is significantly more rapid and clinically relevant after loss of ambulation, which warrants a more vigilant follow-up of respiratory function in this subgroup.

Cardiac Phenotype-Genotype Associations in DMD/BMD: A Meta-Analysis and Systematic Review

Cardiac involvement of Duchenne and Becker muscular dystrophies (DMD/BMD) is the most common cause of fatal outcomes. It is still unclear whether some DMD/BMD gene mutations might be predictive of cardiac involvement. In this study, we provide a comprehensive overview on genotypes of cardiac disease in DMD/BMD. We systematically searched the PubMed/Medline, EMBASE and Cochrane electronic databases. Search results were filtered to include only human studies, English language and all dates up to August 2019. We summarized and extensively reviewed all studies that passed the selection criteria and performed a meta-analysis on key genotype parameters of cardiac disease in DMD/BMD. Of 3450 articles scanned, we included 18 studies from 9 regions in the meta-analysis. The pooled studies included 2661 DMD/BMD patients and 1324 DMD/BMD patients with cardiac disease. The most common mutation type was exon deletion, with a pooled frequency of 90% (P < 0.01). In DMD/BMD patients with cardiac dysfunction, a higher frequency of involvement of exons 45 and 46 was found in DMD/BMD patients with cardiac dysfunction. This might be predictive of cardiac involvement in patients with DMD/BMD.

Population-Wide Duchenne Muscular Dystrophy Carrier Detection by CK and Molecular Testing

Carrier screening of Duchenne muscular dystrophy (DMD) has not been widely evaluated. To identify definite DMD female carriers prior to or in early pregnancy, we studied a large population of reproductive age females and provided informed reproductive options to DMD carriers. 37268 females were recruited from the Hangzhou Family Planning Publicity and Technology Guidance Station/Hangzhou Health Service Center for Children and Women, Hangzhou, China, between October 10, 2017, and December 16, 2018. CK activity was measured with follow-up serum DMD genetic testing in subjects with hyperCKemia, defined as CK > 200 U/L. The calculated upper reference limit (97.5^th percentile) of serum creatine kinase (CK) for females aged 20-50 years in this study was near the reference limit recommended by the manufacturer (200 U/L), above which was defined as hyperCKemia. 427 females (1.2%) harbored initially elevated CK, among which 281 females (response rate of 65.8%) accepted CK retesting. DMD genetic testing was conducted on 62 subjects with sustained serum CK > 200 U/L and 16 females with a family history of DMD. Finally, 6 subjects were confirmed to be DMD definite carriers. The estimated DMD female carrier rate in this study was 1 : 4088 (adjusting for response rate), an underestimated rate, since only 50% to 70% of DMD female carriers manifest elevated serum CK, and carriers in this study may have been missed due to lack of follow-up or inability to detect all DMD pathogenic variants by current genetic testing.

"Betwixt Mine Eye and Heart a League Is Took": The Progress of Induced Pluripotent Stem-Cell-Based Models of Dystrophin-Associated Cardiomyopathy

The ultimate goal of precision disease modeling is to artificially recreate the disease of affected people in a highly controllable and adaptable external environment. This field has rapidly advanced which is evident from the application of patient-specific pluripotent stem-cell-derived precision therapies in numerous clinical trials aimed at a diverse set of diseases such as macular degeneration, heart disease, spinal cord injury, graft-versus-host disease, and muscular dystrophy. Despite the existence of semi-adequate treatments for tempering skeletal muscle degeneration in dystrophic patients, nonischemic cardiomyopathy remains one of the primary causes of death. Therefore, cardiovascular cells derived from muscular dystrophy patients' induced pluripotent stem cells are well suited to mimic dystrophin-associated cardiomyopathy and hold great promise for the development of future fully effective therapies. The purpose of this article is to convey the realities of employing precision disease models of dystrophin-associated cardiomyopathy. This is achieved by discussing, as suggested in the title echoing William Shakespeare's words, the settlements (or "leagues") made by researchers to manage the constraints ("betwixt mine eye and heart") distancing them from achieving a perfect precision disease model.

Variations in native T1 values in patients with Duchenne muscular dystrophy with and without late gadolinium enhancement

Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder leading to progressive skeletal and cardiac myopathy. Elevated myocardial T1 values correlate with fibrosis in most disease processes, but DMD skeletal and cardiac histopathology is defined by fibrofatty replacement that may result in a decrease in T1 values, due to the low T1 of fat. The study goal was to assess myocardial T1 values in DMD patients with and without late gadolinium enhancement (LGE). A retrospective analysis was performed on all patients with DMD referred for CMR at our institution from 7/5/2017 to 10/24/2018. T1 measurements were performed using breath-held modified Look Locker inversion recovery (MOLLI) sequences at the basal and mid-ventricular levels. The cohort was separated into patients without the presence of LGE (LGE-) and patients with current or previous LGE (LGE+). A total of 207 CMR studies were analyzed. The LGE- group comprised 88 patients while 119 patients were in the LGE+ group. The LGE+ group was older, had larger indexed LV end-diastolic volume and lower LV ejection fraction (LVEF) compared to the LGE- group. T1 values in the LGE+ group were lower compared to the LGE- group (mid T1 1012 ms vs. 1035 ms; p = 0.002), with 5 CMR studies demonstrating mid T1 values < 900 ms. There was no correlation between mid T1 and LVEF in the LGE- group. In the LGE+ cohort, lower T1 values correlated with worse LVEF (r = 0.34, p = 0.0002). The association between mid T1 values and LVEF remained statistically significant on multivariable analysis when accounting for number of LGE segments, LVEDVi, and age (p = 0.009). This is the largest study assessing native T1 values in patients with DMD. The results demonstrate that patients with LGE had lower T1 values than patients without LGE. In the LGE+ group, lower T1 values correlated with worse LV systolic function. These results are consistent with the evolving recognition of fibrofatty replacement in advanced stages of DMD myopathy. Furthermore, our study supports that there is not a simple linear relationship between increasing T1 values and advancing disease progression reported in most other cardiomyopathies.

Cardiac involvement in inflammatory myopathies and inherited muscle diseases

PURPOSE OF REVIEW

To examine recent developments relating to cardiac involvement in the adult idiopathic inflammatory myopathies (IIM) and those inherited muscle diseases which may present in adulthood and mimic IIM.

RECENT FINDINGS

Cardiac involvement is a common feature of IIM and inherited muscle diseases. Frequency according to disease subtype varies, with serotype having particular influence in IIM, and genotype in the inherited muscle diseases. Innovative techniques for examining cardiac function have been investigated further, including speckle-tracking echocardiography and cardiac magnetic resonance tomography. The present work has highlighted a likely underestimate of the burden of cardiac disease to date. The complex relationship between IIM, atherosclerosis, and traditional cardiovascular risk factors has been further elucidated. Consensus recommendations for managing patients with inherited muscle diseases and prominent cardiac involvement have been recently published. In addition to supportive care, disease modifying treatments are increasingly becoming available for inherited muscle diseases which may also improve cardiac outcomes.

SUMMARY

Cardiac involvement is associated with significant morbidity and mortality. We suggest having a low threshold for considering the possibility of cardiac involvement in all patients with muscle disease.

Efficacy and safety of ropivacaine HCl in peribulbar anaesthesia for cataract surgery in patients with myotonic dystrophy type 1

Myotonic dystrophy (DM1) is the most common muscle disease in adults, affecting approximately 1:8000 individuals, characterized by myotonia and muscular wasting and a multisystemic involvement that includes heart, brain, respiratory and endocrine system, and eye. Conduction system is selectively involved, often causing cardiac sudden death. Early onset posterior subcapsular cataract is a characteristic feature of myotonic dystrophy, requiring surgical treatment. However, DM1 is associated with many anesthetic hazards; sensitivity to anesthetic drugs, especially muscle relaxants and opioids, may complicate postoperative care. Local anesthesia also requires attention. We investigated the heart response to local anesthesia Ropivacaine Hcl administration in 16 DM1 patients (12M:4F) consecutively undergoing cataract surgery, by analyzing heart rate, ventricular and supraventricular ectopic beats, runs of tachycardia and pauses ≥ 2.5 sec., through a 24h-Holter monitoring, registered before and within 24 hours after surgery. The average age of patients was 47.4 years (range 30.2-55.9). At baseline, one patient had a pacemaker and 3 a defibrillator. Two patients presented a first-degree atrio-ventricular-block; three showed ectopic ventricular beats, on anti-arrhythmic drug treatment. No significant differences in heart rate values (73 ± 15b/m versus 76 ± 13b/m) were observed after cataract surgery, nor in the onset of ectopic beats. Only patients who presented ventricular ectopic beats at baseline, showed an increase in their number after surgery, likely related to an arbitrary interruption of the specific treatment. These data confirm the safety and efficacy of ropivacaine HCl used as a local anesthetic in patients with myotonic dystrophy.

[A case of Emery-Dreifuss muscular dystrophy with slight joint contracture]

A 42-year-old man with a history of two previous coronary embolisms was referred to our hospital. He had been experiencing muscle weakness since he was around 40 years old. He had muscle atrophy of the scapula, upper arm, and lower extremities, and electromyography revealed myogenic changes in the limb muscles. Histopathological analysis of the muscle biopsy specimen revealed a complete deficiency of emerin protein, and genetic examination revealed a mutation in the emerin (EMD) gene, resulting in a diagnosis of Emery-Dreifuss muscular dystrophy (EDMD). EDMD is a muscular disorder with three symptoms: joint contracture at early onset, muscle weakness and atrophy, and cardiac dysfunction. Although this patient showed no obvious joint contracture, the course and clinical symptoms vary among patients. Therefore, in patients in whom clinical diagnosis is difficult, muscle biopsy and genetic testing should be performed for EDMD in order to prevent sudden death due to this disease.

Heart Transplantation in Muscular Dystrophy Patients: Is it a Viable Option?

BACKGROUND

Cardiomyopathy is a common complication among muscular dystrophy (MD) patients and often results in advanced heart failure and premature death. In spite of this, there is hesitancy to consider heart transplantation (HTx). This study describes the HTx outcomes in patients with MD in the United States.

METHODS AND RESULTS

All HTx in the United Network for Organ Sharing database from October 1, 1987, to March 31, 2016, were identified. Two patient groups were created: MD cohort (n=81), and a cohort of all other cardiomyopathies, called cardiomyopathy-unmatched (n=41 317). Propensity score matching (ratio 1:2) was performed on transplant age, gender transplant year, renal function, and inotropic support at transplant to form a cardiomyopathy-matched cohort (n=162). Patient characteristics and posttransplant outcomes were compared. In the 81 patients with MD, Becker was the most common type (42%-52%). All the analyzed preoperative characteristics did not statistically differ between the MD and cardiomyopathy-matched cohorts except ventricular assist device use (16% versus 30%; P=0.017), ventilator support (0% versus 6%; P=0.031), and donor race mismatch (30% versus 55%; P<0.001). Median time on waitlist was not statistically different between the 2 groups (52 versus 59 days; P=0.12). Posttransplant survival of MD cohort was not statistically different compared with cardiomyopathy-matched cohort (P=0.18; hazard ratio [95% CI], 0.71 [0.42-1.18]) and was better than the cardiomyopathy-unmatched cohort (P=0.004; hazard ratio [95% CI], 0.53 [0.34-0.82]). Among the types of MD, no statistical difference was observed in posttransplant survival of Becker MD versus non-Becker MD (P=0.12; hazard ratio [95% CI], 2.17 [0.79-6.01]).

CONCLUSIONS

Patients with MD undergoing HTx had similar long-term posttransplant survival compared with matched cardiomyopathy-related HTx recipients. HTx appears to be an effective treatment for a select group of muscular dystrophy patients with end-stage heart failure.

Comprehensive Assessment of Cardiac Involvement in Muscular Dystrophies by Cardiac MR Imaging

Muscular dystrophy is a group of genetically inherited diseases with irreversible and progressive muscle loss and is associated with cardiac involvement. Particularly in Duchenne and Becker dystrophies, cardiac disorders are the leading causes of mortality. Cardiovascular magnetic resonance imaging (CMR) can detect even incipient myocardial fibrosis (late gadolinium enhancement), which has prognostic significance in patients with preserved left ventricular function by echocardiogram and before the onset of symptoms. Early detection of cardiac abnormalities by CMR enables early cardioprotective treatment, leading to a better prognosis.

Assessing the barriers to cardiac care in carriers of Duchenne and Becker muscular dystrophy

Duchenne and Becker muscular dystrophy (DBMD) are X-linked conditions causing progressive muscle weakness, muscle wasting, and cardiomyopathy in affected males. Two-thirds of cases of DBMD are inherited from a carrier female while one-third of cases occur sporadically. Women who are DBMD carriers typically do not manifest noticeable muscular symptoms. However, about 10% may develop cardiomyopathy while up to 60% are at risk for cardiac abnormalities including myocardial damage, fibrosis, and abnormalities detectable by echocardiogram and electrocardiogram (EKG). The American Academy of Pediatrics (AAP) recommends that carriers of DBMD receive a complete cardiac evaluation beginning at age 25-30 which includes an echocardiogram and EKG, with re-evaluation at least every 5 years. As many as 54.5% carriers may not be adhering to the AAP recommendations (Bogue et al., 2016). This study was conducted to define the perceived challenges carriers of DBMD face in obtaining cardiac care. A questionnaire was completed by 60 carriers of DBMD recruited through The Duchenne Registry to determine their current cardiac care practices. The majority of carriers surveyed (71.7%, 43/60) self-reported obtaining appropriate cardiac care while 28.3% (17/60) of carriers surveyed did not. Eleven semi-structured telephone interviews were conducted with a subset of those who completed the questionnaire. Individuals were eligible for telephone interview if they had not: (a) seen a cardiologist in the last 5 years, (b) had an echocardiogram in the last 5 years, or (c) had an EKG in the last 5 years. The primary theme identified from this cohort was a perceived lack of awareness among healthcare providers regarding cardiac risks in carriers (11/11). Increased awareness, health education regarding risks for carriers, and advocacy efforts are needed for healthcare providers and DBMD carriers in order to ensure that this entire population receives the cardiac care they need.

"The impact of European Neuromuscular Centre (ENMC) workshops on the neuromuscular field; 25 years on …"

Since 1992, the European Neuromuscular Centre facilitated workshops to bring experts in the field of neuromuscular disorders together. After organising more than 235 workshops, it is time to evaluate what impact these 25 years of ENMC workshops have had on the neuromuscular research field and on people affected by a neuromuscular condition. To measure this, workshop topics were retrospectively evaluated and bibliometric analyses on the citation scores of ENMC-derived publications were performed. In addition, a personalized survey was used to investigate the actual achievement and implementation of workshop deliverables. The evaluation of 25 years' workshop topics revealed a strong representation of muscular dystrophies, congenital and mitochondrial myopathies. The publications derived from ENMC workshops scored "high impact" as illustrated by the Mean Normalized Citation Score of 1.24. Also 16% of the ENMC papers belong to the top 10% best cited articles in the neuromuscular field. The main outcome of the personalised survey was that 90% of all workshop deliverables were started and either ongoing or completed. Of these deliverables, 78% were implemented in the field; bringing state-of-the-art knowledge and new collaborations to researchers and clinicians, improving designs of clinical trials and innovating tools to make accurate diagnoses.

Comprehensive evaluation of structural and functional myocardial impairments in Becker muscular dystrophy using quantitative cardiac magnetic resonance imaging

Aims

Becker muscular dystrophy (BMD) is a genetic neuromuscular disease characterized by an alteration of the dystrophin protein. Myocardial involvement is frequent, eventually progressing to a dilated cardiomyopathy, and represents the most common cause of death for this pathology. We performed a comprehensive evaluation of myocardial functional and structural alterations encountered in a large cohort of BMD patients using quantitative cardiac magnetic resonance (CMR) imaging.

Methods and results

Eighty-eight BMD patients and 26 age-matched volunteers underwent standard cine and tag imaging to assess myocardial function and dyssynchrony, while native T1, T2, and extracellular volume fraction (ECV) were measured for tissue characterization. The left ventricular ejection fraction (LV-EF) was significantly reduced in 26% of the BMD patients. Patients exhibited higher dyssynchrony index than controls (6.94 ± 3.17 vs. 5.09 ± 1.25, P = 0.005). Diastolic dyssynchrony also exists in patients where systolic function was normal. BMD subjects, compared with controls, had significantly higher native T1, T2, and ECV (1183 ± 60 ms vs. 1164 ± 22 ms, 47.5 ± 4.5 ms vs. 45.6 ± 3.4 ms, 0.282 ± 0.050 vs. 0.231 ± 0.027, respectively, P < 0.05). Native T1, T2, and ECV correlated with LV-EF (R = −0.79, −0.70, and −0.71, respectively, P < 0.001) and N-terminal-pro brain natriuretic peptide (R = 0.51, 0.58, and 0.44, respectively, P < 0.001).

Conclusion

Quantitative CMR represents a powerful tool to evaluate structural and functional impairments in the myocardium of BMD subjects. Native T1, T2, and ECV provided quantitative biomarkers related to inflammation and fibrosis, and could stratify disease severity.

Rehabilitation Management of the Patient With Duchenne Muscular Dystrophy

Steadily improving management of Duchenne muscular dystrophy (DMD) continues to lead to improved physical and functional status, allowing increasingly successful transitions to independence and self-actualization in adulthood. Rehabilitation principles remain key to overall management for individuals with DMD with increasing options for ever more successful management, reflecting a changing natural history based on the use of glucocorticoids, more consistent comprehensive care, and the emergence of disease-modifying treatments. Advances and expansion in assessment, cardiorespiratory management, preventive management of contracture and deformity, assistive technology, "smart" technology, and robotics with increased emphasis on function, participation, self-advocacy, and independence in decision-making should allow individuals with DMD to experience childhood and transition to adulthood with support that allows for increasing success in the achievement of individual goals and fulfillment across the life span.

DMD mutation and LTBP4 haplotype do not predict onset of left ventricular dysfunction in Duchenne muscular dystrophy

Cardiomyopathy develops in >90% of Duchenne muscular dystrophy (DMD) patients by the second decade of life. We assessed the associations between DMD gene mutations, as well as Latent transforming growth factor-beta-binding protein 4 (LTBP4) haplotypes, and age at onset of myocardial dysfunction in DMD. DMD patients with baseline normal left ventricular systolic function and genotyping between 2004 and 2013 were included. Patients were grouped in multiple ways: specific DMD mutation domains, true loss-of-function mutations (group A) versus possible residual gene expression (group B), and LTBP4 haplotype. Age at onset of myocardial dysfunction was the first echocardiogram with an ejection fraction <55% and/or shortening fraction <28%. Of 101 DMD patients, 40 developed cardiomyopathy. There was no difference in age at onset of myocardial dysfunction among DMD genotype mutation domains (13.7±4.8 versus 14.3±1.0 versus 14.3±2.9 versus 13.8±2.5, p=0.97), groups A and B (14.4±2.8 versus 12.1±4.4, p=0.09), or LTBP4 haplotypes (14.5±3.2 versus 13.1±3.2 versus 11.0±2.8, p=0.18). DMD gene mutations involving the hinge 3 region, actin-binding domain, and exons 45-49, as well as the LTBP4 IAAM haplotype, were not associated with age of left ventricular dysfunction onset in DMD.

Female dystrophinopathy: Review of current literature

Skeletal muscle or cardiac symptoms are known to appear in a certain proportion of female patients carrying the dystrophin gene mutation. There is limited high-quality evidence to guide the treatment of female carriers of Duchenne muscular dystrophy/Becker muscular dystrophy (DMD/BMD). The available evidence is mainly based on expert opinions and clinical experience. To improve this situation, we reviewed 1002 reports published from 1967 to 2017 to assess the following themes: epidemiology, clinical symptoms, cardiomyopathy, burdens on parents or caregivers, pregnancy or delivery, and prognosis. We aimed to provide guidance for the provision of support, care, and education for patients, caregivers, and health care professionals. There were 271 reports before 1987, and 731 reports after 1987 when dystrophin was first recognized. In this review, we mainly selected 37 papers that were reported after 1987. In seven large research papers, the incidence of skeletal muscle damage among female carriers, including asymptomatic carriers, was reported as 2.5%-19%, and the incidence of dilated cardiomyopathy was 7.3%-16.7% for DMD and 0%-13.3% for BMD. We integrated and summarized the genetically definite manifesting carriers with skeletal muscle symptoms from 10 case series. In combined data, among 93 manifesting carriers, 16 (17.2%) presented with cardiac abnormalities. The frequency of manifesting carriers complicated by cardiomyopathy increased with age. Reports on cardiac magnetic resonance in female carriers and the burden on caregivers are increasing, whereas literatures concerning pregnancy, delivery, and prognosis in female carriers are limited. This represents a future direction for research.

Can Human Pluripotent Stem Cell-Derived Cardiomyocytes Advance Understanding of Muscular Dystrophies?

Muscular dystrophies (MDs) are clinically and molecularly a highly heterogeneous group of single-gene disorders that primarily affect striated muscles. Cardiac disease is present in several MDs where it is an important contributor to morbidity and mortality. Careful monitoring of cardiac issues is necessary but current management of cardiac involvement does not effectively protect from disease progression and cardiac failure. There is a critical need to gain new knowledge on the diverse molecular underpinnings of cardiac disease in MDs in order to guide cardiac treatment development and assist in reaching a clearer consensus on cardiac disease management in the clinic. Animal models are available for the majority of MDs and have been invaluable tools in probing disease mechanisms and in pre-clinical screens. However, there are recognized genetic, physiological, and structural differences between human and animal hearts that impact disease progression, manifestation, and response to pharmacological interventions. Therefore, there is a need to develop parallel human systems to model cardiac disease in MDs. This review discusses the current status of cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSC) to model cardiac disease, with a focus on Duchenne muscular dystrophy (DMD) and myotonic dystrophy (DM1). We seek to provide a balanced view of opportunities and limitations offered by this system in elucidating disease mechanisms pertinent to human cardiac physiology and as a platform for treatment development or refinement.

Evaluation of cardiac functions in children with Duchenne Muscular Dystrophy: A prospective case-control study

Background

Duchenne muscular dystrophy (DMD) is the most common childhood form of muscular dystrophy. The incidence of cardiomyopathy in DMD increases with age, so its early detection is important because institution of cardioprotective medical therapies may slow adverse remodeling and attenuate heart failure symptoms in these patients.

Objective

To assess the cardiac functions in children clinically suspected to have DMD.

Methods

Over a one-year period, 28 male children aged from 3 to 18 years old, who met the criteria for diagnosis of DMD compared to 47 healthy controls children, were approached to participate in the study. The included children were subjected to full clinical examination, and blood samples were collected to determine creatinine phosphokinase (CPK), troponin I enzyme, myoglobin and lactate dehydrogenase (LDH) enzyme level. Echocardiography and 12-leads electrocardiogram (ECG) were also done for children in both groups. Data were analyzed using Independent-samples t-test, Mann-Whitney U, Chi square, and Fisher’s exact test.

Results

The mean age of the cases group was 7.29±3.24 years versus 8.06±2.86 years for controls. In DMD group, 25% had positive family history of DMD while 35.7% of them had positive consanguinity. All cases had elevated CPK level while CPK level in controls was normal (p<0.0001). LDH level was elevated in 19 cases (67.86%) of DMD while all controls children had normal LDH level (p<0.0001). Furthermore, the mean serum myoglobin level of DMD patients was higher relative to that of healthy controls (39.39±7.25 versus 33.68 ±12.38 ng/ml respectively) (p=0.01). Echocardiography of our patients revealed that seven cases (25%) had low ejection fraction (EF) and fraction shortening (FS). In addition, all controls children had normal EF (p<0.0001) and normal FS (p<0.0001). Interestingly, ECG showed that 28.57% of cases had sinus tachycardia vs. 6.88% for controls (p=0.0001). Prolonged QTc interval was present in 39.29% of cases (mean 431.39±43.60) while all controls had normal QTc duration for age (mean of 415.17±25.2) (p<0.0001).

Conclusion

ECG manifestations in children with DMD in the form of sinus tachycardia and prolonged QTc interval are an early alarm for developing cardiomyopathy before overt echocardiographic findings appear.

Rapidly progressive heart failure requiring transplantation in muscular dystrophy: a need for frequent screening

Fukuyama congenital muscular dystrophy weakens both skeletal and cardiac muscles, but the rate of cardiomyopathic progression can accelerate faster than that of skeletal muscles. A 14-year-old boy with Fukuyama congenital muscular dystrophy presented with mild skeletal myopathy but severe cardiomyopathy requiring heart transplantation within 1 year of declining heart function. These patients need frequent screening regardless of musculoskeletal symptoms.

Cardiac involvement in myotonic dystrophy: The role of troponins and N-terminal pro B-type natriuretic peptide

BACKGROUND AND AIMS

Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are dominant inherited muscular dystrophies with multiple systemic involvement, often producing cardiac injury. This study sought to determine the clinical significance of elevated high sensitivity cardiac troponin T and I (hs-cTnT and hs-cTnI), and N-terminal pro B-type natriuretic peptide (NT-pro-BNP) in this population.

METHODS

Sixty DM patients (35 men and 25 women; mean age: 45.1 years, range: 12-73 years) underwent clinical cardiac investigations and measurements of serum hs-cTnT, hs-cTnI, creatine kinase (CK), and NT-proBNP. Left ventricular (LV) ejection fraction (EF) was assessed by echocardiography.

RESULTS

Genetic analysis revealed that 46 of the 60 patients were DM1, and 14 DM2. Blood measurements showed persistent elevation of hs-cTnT and CK in 55/60 DM patients (91.73%). In contrast, hs-cTnI values were persistently normal throughout the study. Only 2 patients showed an EF <50%, being the overall range of this population between 40% and 79%. We found ECG abnormalities in 19 patients. Of these patients, 13 showed first or second-degree atrio ventricular (AV) blocks (PR interval ≥ 200 ms), 4 showed a left bundle branch block (LBBB) prolonged (QRS duration ≥120 ms), and 2 had an incomplete bundle branch block (QRS duration between 110 and 119 ms). After excluding patients with EF <50%, NT-pro-BNP measurement > 125 pg/mL was an independent predictor of ECG abnormalities.

CONCLUSIONS

NT-pro-BNP levels may be considered to be used clinically to identify DM patients at increased risk of developing myocardial conduction abnormalities.

Neuromuscular Disorders and the Role of the Clinical Electrophysiologist

Cardiac involvement is common and may be the presenting or predominant manifestation in a variety of neuromuscular disorders, most notably the inherited muscle disorders, or muscular dystrophies. Cardiac manifestations of the neuromuscular disorders result from pathological involvement of the myocardium and the cardiac conduction system, with resulting cardiomyopathy or rhythm disturbances including supraventricular arrhythmias, life-threatening ventricular arrhythmias, and sudden cardiac death. Many of these neuromuscular disorders are rare and may be unrecognized by even experienced specialists in internal and cardiovascular medicine. Furthermore, the initial cardiac manifestations in these patients are often asymptomatic. The goal of this investigation is to review the scope of cardiac conduction defects and rhythm disturbances in these disorders and to propose some practical recommendations for arrhythmia monitoring and management of these patients.

Prenatal diagnosis of Duchenne and Becker muscular dystrophies: Underestimated problem of the secondary prevention of monogenetic disorders

AIM

The aim of this study was to analyze the influence of effective preconceptional testing for carrier status in women at risk for Duchenne and Becker muscular dystrophies (D/BMD) on the prenatal diagnosis.

METHODS

A retrospective analysis of 201 prenatal tests was performed in 169 Polish women at risk, in regard to time of testing for carrier status (prior to conception or during pregnancy) and carrier status of tested women, including confirmed D/BMD carriers (n = 78; 46.2%), D/BMD non-carriers - tested for germline mosaicism risk (n = 23; 13.6%), and women at risk with uncertain carrier status (n = 68; 40.2%).

RESULTS

Only 52.7% of women were tested for D/BMD carrier status prior to conception and in these women prenatal diagnosis was carried out more frequently in the first trimester of pregnancy (64.7% vs 47.8%; P = 0.035). The results of prenatal testing in male fetuses in pregnancies of confirmed D/BMD carriers and D/BMD non-carriers - tested for germline mosaicism risk were conclusive in all cases, whereas in women with uncertain carrier status, only 60.0% of results were conclusive. Eighty-five of 103 female fetuses (82.5%) were tested prenatally and in 31.8% of them fetal carrier status was confirmed.

CONCLUSION

Carrier status testing in women prior to conception has a positive impact on the frequency of first-trimester prenatal diagnosis and known D/BMD carrier status on the effectiveness of prenatal diagnosis. Due to the low percentage of women tested effectively prior to conception, carrier status testing in the families at risk should be propagated (including possibility of prenatal diagnosis of female fetuses).

Sleep and the Cardiovascular System in Children

Subspecialty pediatric practice provides comprehensive medical care for a range of ages, from premature infants to children, and often includes adults with complex medical and surgical issues that warrant multidisciplinary care. Normal physiologic variations involving different body systems occur during sleep and these vary with age, stage of sleep, and underlying health conditions. This article is a concise review of the cardiovascular (CV) physiology and pathophysiology in children, sleep-disordered breathing (SDB) contributing to CV morbidity, congenital and acquired CV pathology resulting in SDB, and the relationship between SDB and CV morbidity in different clinical syndromes and systemic diseases in the expanded pediatric population.