Life expectancy and death from cardiomyopathy amongst carriers of Duchenne and Becker muscular dystrophy in Scotland

Long-term outcomes for females with early-onset dystrophinopathy

AIM

To study long-term disease course for females with early-onset dystrophinopathy, including common (female) symptoms, challenges in social participation, the need for care, and current healthcare management to support guideline development.

METHOD

Twelve females with early-onset dystrophinopathy were followed for a median period of more than 17 years (range 1-36).

RESULTS

One patient died owing to end-stage cardiac failure. Cardiac abnormalities were observed in three of the remaining 11 participants. Respiratory function was reduced in seven of 10 participants. Fatigue, myalgia, lower back pain, and arthralgia were reported in more than six of the participants. Functional status varied from exercise intolerance to wheelchair dependency. Most or all of the 10 participants reported restrictions in participation in work (n = 10), household duties (n = 10), sports (n = 9), and education (n = 8). Only a few participants received followed-up pulmonary (n = 2) or rehabilitation (n = 3) care.

INTERPRETATION

Females with early-onset dystrophinopathy experience a wide range of impairments, comorbidities, limitations in activities, and restrictions in social participation. The whole spectrum should be acknowledged in the healthcare setting. Neuromuscular and cardiac follow-up are indispensable. Additional respiratory assessment and rehabilitation care are expected to improve health status and support daily activities and participation.

WHAT THIS PAPER ADDS

No standard diagnostic procedures seem to exist for female patients suspected for dystrophinopathy. Female participants with early-onset dystrophinopathy experienced a broad scope of burdening symptoms, such as fatigue, myalgia, lower back pain, and arthralgia. None of participants worked full time, all felt restricted in paid work, and most felt restricted in education. Most participants showed decreased lung function, while only one was symptomatic. Availability of rehabilitation care may improve support for daily activities and participation for females with early-onset dystrophinopathy.

SNTA1 gene rescues ion channel function and is antiarrhythmic in cardiomyocytes derived from induced pluripotent stem cells from muscular dystrophy patients

Background

Patients with cardiomyopathy of Duchenne Muscular Dystrophy (DMD) are at risk of developing life-threatening arrhythmias, but the mechanisms are unknown. We aimed to determine the role of ion channels controlling cardiac excitability in the mechanisms of arrhythmias in DMD patients.

Methods

To test whether dystrophin mutations lead to defective cardiac NaV1.5-Kir2.1 channelosomes and arrhythmias, we generated iPSC-CMs from two hemizygous DMD males, a heterozygous female, and two unrelated control males. We conducted studies including confocal microscopy, protein expression analysis, patch-clamping, non-viral piggy-bac gene expression, optical mapping and contractility assays.

Results

Two patients had abnormal ECGs with frequent runs of ventricular tachycardia. iPSC-CMs from all DMD patients showed abnormal action potential profiles, slowed conduction velocities, and reduced sodium (INa) and inward rectifier potassium (IK1) currents. Membrane NaV1.5 and Kir2.1 protein levels were reduced in hemizygous DMD iPSC-CMs but not in heterozygous iPSC-CMs. Remarkably, transfecting just one component of the dystrophin protein complex (α1-syntrophin) in hemizygous iPSC-CMs from one patient restored channelosome function, INa and IK1 densities, and action potential profile in single cells. In addition, α1-syntrophin expression restored impulse conduction and contractility and prevented reentrant arrhythmias in hiPSC-CM monolayers.

Conclusions

We provide the first demonstration that iPSC-CMs reprogrammed from skin fibroblasts of DMD patients with cardiomyopathy have a dysfunction of the NaV1.5-Kir2.1 channelosome, with consequent reduction of cardiac excitability and conduction. Altogether, iPSC-CMs from patients with DMD cardiomyopathy have a NaV1.5-Kir2.1 channelosome dysfunction, which can be rescued by the scaffolding protein α1-syntrophin to restore excitability and prevent arrhythmias.

Funding

Supported by National Institutes of Health R01 HL122352 grant; 'la Caixa' Banking Foundation (HR18-00304); Fundación La Marató TV3: Ayudas a la investigación en enfermedades raras 2020 (LA MARATO-2020); Instituto de Salud Carlos III/FEDER/FSE; Horizon 2020 - Research and Innovation Framework Programme GA-965286 to JJ; the CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación (MCIN) and the Pro CNIC Foundation), and is a Severo Ochoa Center of Excellence (grant CEX2020-001041-S funded by MICIN/AEI/10.13039/501100011033). American Heart Association postdoctoral fellowship 19POST34380706s to JVEN. Israel Science Foundation to OB and MA [824/19]. Rappaport grant [01012020RI]; and Niedersachsen Foundation [ZN3452] to OB; US-Israel Binational Science Foundation (BSF) to OB and TH [2019039]; Dr. Bernard Lublin Donation to OB; and The Duchenne Parent Project Netherlands (DPPNL 2029771) to OB. National Institutes of Health R01 AR068428 to DM and US-Israel Binational Science Foundation Grant [2013032] to DM and OB.

A population-based study of mortality due to muscular dystrophies across a 36-year period in Spain

Muscular dystrophies (MD) are a group of rare hereditary degenerative diseases. Our aim was to analyze the mortality pattern in Spain from 1981 to 2016 to assess the temporal trend and discern possible geographic differences using population-based data. Annual deaths related to MD were obtained from the National Statistics Institute with codes 359.1 of the ICD-9 (1981–1998) and G71.0 of the ICD-10 (1999–2016). Age-adjusted mortality rates were calculated and changes in mortality trends were identified. The standardized mortality ratios (SMR) and their respective 95% confidence intervals were calculated by district for 1999–2016. Smoothed SMRs and posterior probability were also assessed and then mapped to look for patterns or geographic distribution. All rates were expressed per 1,000,000 inhabitants. A total of 2,512 deaths (73.8% men) were identified. The age-adjusted mortality rates varied from 0.63 (95% CI 0.40–0.95) in 1981 to 1.51 (95% CI 1.17–1.93) in 2016. MD mortality showed a significant increase of 8.81% per year (95% CI 5.0–12.7) from 1981 to 1990, remaining stable afterwards. Areas with risk of death higher than expected for Spain as a whole were identified, not showing a specific regional pattern. In conclusion, the rising trend in MD mortality might be attributable to advanced improvements in diagnostic techniques leading to a rise in prevalence. Further research on the districts with the highest mortality would be necessary.

Natural History of Histopathologic Changes in Cardiomyopathy of Golden Retriever Muscular Dystrophy

Background

Duchenne muscular dystrophy (DMD) is an X-linked inherited myopathy that causes progressive skeletal and cardiac muscle disease. Heart lesions were described in the earliest DMD reports, and cardiomyopathy is now the leading cause of death. However, diagnostics and treatment for cardiomyopathy have lagged behind those for appendicular and respiratory skeletal muscle disease. Most animal model studies have been done in the mdx mouse, which has a relatively mild form of cardiomyopathy. Dogs with the genetically homologous condition, Golden Retriever muscular dystrophy (GRMD), develop progressive cardiomyopathy analogous to that seen in DMD. Previous descriptive studies of GRMD cardiomyopathy have mostly been limited to selective sampling of the hearts from young dogs.

Methods and Results

We systematically assessed cardiac lesions in 31 GRMD and carrier dogs aged 3 to 76 months and a separate cohort of 2–10-year-old normal hounds. Both semi-quantitative lesion scoring and quantitation of the cross-sectional area of fibrosis distinguished dogs with GRMD disease from normal dogs. The carriers generally had intermediate involvement but had even greater fibrosis than GRMD dogs. Fatty infiltration was the most prominent feature in some older GRMD dogs. Vascular hypertrophy was increased in GRMD dogs and correlated positively with lesion severity. Purkinje fiber vacuolation was also increased but did not correlate with lesion severity. Histopathologic changes correlated with late gadolinium enhancement on cardiac MRI.

Conclusion

These features are generally compatible with those of DMD and further validate GRMD as a useful model to study cardiomyopathy pathogenesis and treatment. Additionally, the nature of some degenerative lesions suggests that functional hypoxia or non-thrombotic ischemia may contribute to disease progression.

Sex Differences in Heart Failure

Heart failure (HF) continues to be a major contributor of morbidity and mortality for men and women alike, yet how the predisposition for, course and management of HF differ between men and women remains underexplored. Sex differences in traditional risk factors as well as sex-specific risk factors influence the prevalence and manifestation of HF in unique ways. The pathophysiology of HF differs between men and women and may explain sex-specific differences in clinical presentation and diagnosis. This in turn contributes to variation in response to both pharmacologic and device/surgical therapy. This review examines sex-specific differences in HF spanning prevalence, risk factors, pathophysiology, presentation, and therapies with a specific focus on highlighting gaps in knowledge with calls to action for future research efforts.

Cardiac Involvement in Women With Pathogenic Dystrophin Gene Variants

Objective: To determine the frequency and extent of cardiac involvement in female carriers of pathogenic variants in DMD, 53 women were examined through an observational, cross-sectional study.

Methods: Genetically verified female carriers of pathogenic DMD variants were examined by cardiac magnetic resonance imaging (CMR) with late gadolinium enhancement, echocardiography, 24-h Holter monitoring, ECG, and blood concentrations of skeletal and cardiac muscle biomarkers.

Results: Fifty-three female carriers of pathogenic DMD variants (mean age 49.6 years, 33 associated with DMD, and 20 with BMD) were included in the study. Sixty-two percent had cardiac dysfunction on echocardiography. On CMR, 49% had myocardial fibrosis, 35% had dilated left ventricles, and 10% had left ventricular hypertrophy. ECGs were abnormal in 72%, and abnormal Holter monitoring was found in 43%. Age did not correlate with myocardial fibrosis or cardiac dysfunction. Myocardial fibrosis was more frequent in carriers of pathogenic variants associated with DMD vs. BMD (61 vs. 28%, p = 0.02).

Conclusion: This study shows that cardiac involvement, affecting both structure and function of the heart, is found in over 2/3 of women with a pathogenic DMD variant. The study supports early cardiac screening, including ECG, Holter, and cardiac imaging, in this group of carriers, so that symptoms related to pathogenic variants in DMD can be recognized, and relevant treatment can be initiated. Longitudinal studies are needed to assess morbidity and mortality related to single, pathogenic DMD variants in women.

Duchenne muscular dystrophy

Duchenne muscular dystrophy is a severe, progressive, muscle-wasting disease that leads to difficulties with movement and, eventually, to the need for assisted ventilation and premature death. The disease is caused by mutations in DMD (encoding dystrophin) that abolish the production of dystrophin in muscle. Muscles without dystrophin are more sensitive to damage, resulting in progressive loss of muscle tissue and function, in addition to cardiomyopathy. Recent studies have greatly deepened our understanding of the primary and secondary pathogenetic mechanisms. Guidelines for the multidisciplinary care for Duchenne muscular dystrophy that address obtaining a genetic diagnosis and managing the various aspects of the disease have been established. In addition, a number of therapies that aim to restore the missing dystrophin protein or address secondary pathology have received regulatory approval and many others are in clinical development.

Sex differences in heart failure

The overall lifetime risk of heart failure (HF) is similar between men and women, however, there are marked sex differences in the landscape of this condition that are both important and under-recognized. Men are predisposed to HF with reduced ejection fraction (HFrEF), whereas women predominate in HF with preserved ejection fraction (HFpEF). Sex differences are also notable in the penetrance of genetic cardiomyopathies, risk factors, e.g. breast cancer which may be associated with cancer treatment-induced cardiomyopathy, as well as sex-specific conditions such as peripartum cardiomyopathy (PPCM). This review outlines the key sex differences with respect to clinical characteristics, pathophysiology, and therapeutic responses to HF treatments. Finally, we address important differences in the prognosis of HF. A central hypothesis is that the higher risk of HFrEF in men compared to women may be attributable to their predisposition to macrovascular coronary artery disease and myocardial infarction, whereas coronary microvascular dysfunction/endothelial inflammation has been postulated to play a key role in HFpEF and maybe the common link among HF syndromes that women are predisposed to Takotsubo cardiomyopathy, PPCM, and breast cancer radiotherapy-induced cardiomyopathy. Under-pinning current sex disparities in HF, there is a paucity of women recruited to HF clinical trials (20–25% of cohorts) and thus treatment guidelines are predominantly based on male-derived data. Large gaps in knowledge exist in sex-specific mechanisms, optimal drug doses for women and sex-specific criteria for device therapy.

Interventions for preventing and treating cardiac complications in Duchenne and Becker muscular dystrophy and X-linked dilated cardiomyopathy

BACKGROUND

The dystrophinopathies include Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and X-linked dilated cardiomyopathy (XLDCM). In recent years, co-ordinated multidisciplinary management for these diseases has improved the quality of care, with early corticosteroid use prolonging independent ambulation, and the routine use of non-invasive ventilation signficantly increasing survival. The next target to improve outcomes is optimising treatments to delay the onset or slow the progression of cardiac involvement and so prolong survival further.

OBJECTIVES

To assess the effects of interventions for preventing or treating cardiac involvement in DMD, BMD, and XLDCM, using measures of change in cardiac function over six months.

SEARCH METHODS

On 16 October 2017 we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE and Embase, and on 12 December 2017, we searched two clinical trials registries. We also searched conference proceedings and bibliographies.

SELECTION CRITERIA

We considered only randomised controlled trials (RCTs), quasi-RCTs and randomised cross-over trials for inclusion. In the Discussion, we reviewed open studies, longitudinal observational studies and individual case reports but only discussed studies that adequately described the diagnosis, intervention, pretreatment, and post-treatment states and in which follow-up lasted for at least six months.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed the titles and abstracts identified from the search and performed data extraction. All three authors assessed risk of bias independently, compared results, and decided which trials met the inclusion criteria. They assessed the certainty of evidence using GRADE criteria.

MAIN RESULTS

We included five studies (N = 205) in the review; four studies included participants with DMD only, and one study included participants with DMD or BMD. All studied different interventions, and meta-analysis was not possible. We found no studies for XLDCM. None of the trials reported cardiac function as improved or stable cardiac versus deteriorated.The randomised first part of a two-part study of perindopril (N = 28) versus placebo (N = 27) in boys with DMD with normal heart function at baseline showed no difference in the number of participants with a left ventricular ejection fraction (LVEF%) of less than 45% after three years of therapy (n = 1 in each group; risk ratio (RR) 1.04, 95% confidence interval (CI) 0.07 to 15.77). This result is uncertain because of study limitations, indirectness and imprecision. In a non-randomised follow-up study, after 10 years, more participants who had received placebo from the beginning had reduced LVEF% (less than 45%). Adverse event rates were similar between the placebo and treatment groups (low-certainty evidence).A study comparing treatment with lisinopril versus losartan in 23 boys newly diagnosed with Duchenne cardiomyopathy showed that after 12 months, both were equally effective in preserving or improving LVEF% (lisinopril 54.6% (standard deviation (SD) 5.19), losartan 55.2% (SD 7.19); mean difference (MD) -0.60% CI -6.67 to 5.47: N = 16). The certainty of evidence was very low because of very serious imprecision and study limitations (risk of bias). Two participants in the losartan group were withdrawn due to adverse events: one participant developed an allergic reaction, and a second exceeded the safety standard with a fall in ejection fraction greater than 10%. Authors reported no other adverse events related to the medication (N = 22; very low-certainty evidence).A study comparing idebenone versus placebo in 21 boys with DMD showed little or no difference in mean change in cardiac function between the two groups from baseline to 12 months; for fractional shortening the mean change was 1.4% (SD 4.1) in the idebenone group and 1.6% (SD 2.6) in the placebo group (MD -0.20%, 95% CI -3.07 to 2.67, N = 21), and for ejection fraction the mean change was -1.9% (SD 9.8) in the idebenone group and 0.4% (SD 5.5) in the placebo group (MD -2.30%, 95% CI -9.18 to 4.58, N = 21). The certainty of evidence was very low because of study limitations and very serious imprecision. Reported adverse events were similar between the treatment and placebo groups (low-certainty evidence).A multicentre controlled study added eplerenone or placebo to 42 patients with DMD with early cardiomyopathy but preserved left ventricular function already established on ACEI or ARB therapy. Results showed that eplerenone slowed the rate of decline of magnetic resonance (MR)-assessed left ventricular circumferential strain at 12 months (eplerenone group median 1.0%, interquartile range (IQR) 0.3 to -2.2; placebo group median 2.2%, IQR 1.3 to -3.1%; P = 0.020). The median decline in LVEF over the same period was also less in the eplerenone group (-1.8%, IQR -2.9 to 6.0) than in the placebo group (-3.7%, IQR -10.8 to 1.0; P = 0.032). We downgraded the certainty of evidence to very low for study limitations and serious imprecision. Serious adverse events were reported in two patients given placebo but none in the treatment group (very low-certainty evidence).A randomised placebo-controlled study of subcutaneous growth hormone in 16 participants with DMD or BMD showed an increase in left ventricular mass after three months' treatment but no significant improvement in cardiac function. The evidence was of very low certainty due to imprecision, indirectness, and study limitations. There were no clinically significant adverse events (very low-certainty evidence).Some studies were at risk of bias, and all were small. Therefore, although there is some evidence from non-randomised data to support the prophylactic use of perindopril for cardioprotection ahead of detectable cardiomyopathy, and for lisinopril or losartan plus eplerenone once cardiomyopathy is detectable, this must be considered of very low certainty. Findings from non-randomised studies, some of which have been long term, have led to the use of these drugs in daily clinical practice.

AUTHORS' CONCLUSIONS

Based on the available evidence from RCTs, early treatment with ACE inhibitors or ARBs may be comparably beneficial for people with a dystrophinopathy; however, the certainty of evidence is very low. Very low-certainty evidence indicates that adding eplerenone might give additional benefit when early cardiomyopathy is detected. No clinically meaningful effect was seen for growth hormone or idebenone, although the certainty of the evidence is also very low.

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.

Cardiomyopathy in becker muscular dystrophy: Overview

Becker muscular dystrophy (BMD) is an X-linked recessive disorder involving mutations of the dystrophin gene. Cardiac involvement in BMD has been described and cardiomyopathy represents the number one cause of death in these patients. In this paper, the pathophysiology, clinical evaluations and management of cardiomyopathy in patients with BMD will be discussed.

Cardiac structure and function in female carriers of a canine model of Duchenne muscular dystrophy

This investigation tested the hypothesis that carriers of golden retriever muscular dystrophy (GRMD), a genetically homologous condition of Duchenne muscular dystrophy (DMD), have quantifiable abnormalities in myocardial function, structure, or cardiac rhythm. Eleven GRMD carriers and four matched controls had cardiac evaluations and postmortem examinations. 24-h ECG Holter monitoring disclosed ventricular ectopy in 10 of 11 carriers and 2 of 4 controls. Conventional echocardiography failed to demonstrate significant differences between carriers and controls in systolic function. All carriers had multifocal, minimal to marked myofiber necrosis, fibrosis, mineralization, inflammation, and/or fatty change in their hearts. Immunohistochemistry revealed a mosaic dystrophin deficiency in scattered cardiac myofibers in all carriers. No controls had cardiac histologic lesions; all had uniform dystrophin staining. Despite cardiac mosaic dystrophin expression and degenerative cardiac lesions, GRMD carriers at up to 3 years of age could not be distinguished statistically from normal controls by echocardiography or 24-h Holter monitoring.

Progress in gene therapy of dystrophic heart disease

The heart is frequently afflicted in muscular dystrophy. In severe cases, cardiac lesion may directly result in death. Over the years, pharmacological and/or surgical interventions have been the mainstay to alleviate cardiac symptoms in muscular dystrophy patients. Although these traditional modalities remain useful, the emerging field of gene therapy has now provided an unprecedented opportunity to transform our thinking/approach in the treatment of dystrophic heart disease. In fact, the premise is already in place for genetic correction. Gene mutations have been identified and animal models are available for several types of muscular dystrophy. Most importantly, innovative strategies have been developed to effectively deliver therapeutic genes to the heart. Dystrophin-deficient Duchenne cardiomyopathy is associated with Duchenne muscular dystrophy (DMD), the most common lethal muscular dystrophy. Considering its high incidence, there has been a considerable interest and significant input in the development of Duchenne cardiomyopathy gene therapy. Using Duchenne cardiomyopathy as an example, here we illustrate the struggles and successes experienced in the burgeoning field of dystrophic heart disease gene therapy. In light of abundant and highly promising data with the adeno-associated virus (AAV) vector, we have specially emphasized on AAV-mediated gene therapy. Besides DMD, we have also discussed gene therapy for treating cardiac diseases in other muscular dystrophies such as limb-girdle muscular dystrophy.

Canine models of Duchenne muscular dystrophy and their use in therapeutic strategies

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder in which the loss of dystrophin causes progressive degeneration of skeletal and cardiac muscle. Potential therapies that carry substantial risk, such as gene- and cell-based approaches, must first be tested in animal models, notably the mdx mouse and several dystrophin-deficient breeds of dogs, including golden retriever muscular dystrophy (GRMD). Affected dogs have a more severe phenotype, in keeping with that of DMD, so may better predict disease pathogenesis and treatment efficacy. Various phenotypic tests have been developed to characterize disease progression in the GRMD model. These biomarkers range from measures of strength and joint contractures to magnetic resonance imaging. Some of these tests are routinely used in clinical veterinary practice, while others require specialized equipment and expertise. By comparing serial measurements from treated and untreated groups, one can document improvement or delayed progression of disease. Potential treatments for DMD may be broadly categorized as molecular, cellular, or pharmacologic. The GRMD model has increasingly been used to assess efficacy of a range of these therapies. A number of these studies have provided largely general proof-of-concept for the treatment under study. Others have demonstrated efficacy using the biomarkers discussed. Importantly, just as symptoms in DMD vary among patients, GRMD dogs display remarkable phenotypic variation. Though confounding statistical analysis in preclinical trials, this variation offers insight regarding the role that modifier genes play in disease pathogenesis. By correlating functional and mRNA profiling results, gene targets for therapy development can be identified.

Exercise-induced left ventricular systolic dysfunction in women heterozygous for dystrophinopathy

BACKGROUND

Mutations in the X-linked gene encoding dystrophin cause skeletal and cardiac muscle diseases in men. Female "carriers" also can develop overt disease. The purpose of this study was to ascertain the prevalence of cardiac contractile abnormalities in dystrophinopathy carriers.

METHODS

Twenty-four dystrophinopathy heterozygotes and 24 normal women each underwent standard exercise stress echocardiography.

RESULTS

Heterozygotes demonstrated mildly lower left ventricular ejection fractions (LVEFs) at rest compared with controls (0.56 + or - 0.10 vs 0.62 + or - 0.07, P = .02). After exercise, the mean LVEF fell to 0.53 + or - 0.14 in heterozygotes but rose to 0.73 + or - 0.07 in controls (P < .001). Twenty-one of 24 dystrophinopathy heterozygotes demonstrated > or = 1 of the following: abnormal resting LVEF, abnormal LVEF response to exercise, or exercise-induced wall motion abnormality.

CONCLUSIONS

Women heterozygous for dystrophinopathy demonstrate significant left ventricular systolic dysfunction, which is unmasked by exercise. This finding has mechanistic implications for both inherited and acquired cardiac disease states.

Diagnostic utility of cardiac magnetic resonance for detection of cardiac involvement in female carriers of Duchenne muscular dystrophy

BACKGROUND

Cardiac involvement is a recognised complication in female carriers of Duchenne muscular dystrophy (DMD). Since segmental or global left ventricle (LV) wall motion abnormalities in DMD carriers can arise even without apparent muscle weakness, it is difficult to differentiate cardiac involvement of a DMD carrier from other heart diseases in a non-invasive manner. Cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE) enables assessment of regional wall motion abnormality and myocardial damage with high spatial resolution.

OBJECTIVE

To assess the utility of CMR for detection of myocardial damage in female carriers of DMD.

METHODS AND RESULTS

Gadolinium-enhanced CMR was performed in seven female DMD carriers. Physical examination, electrocardiography, chest radiograph, measurements of total creatinine kinase and brain natriuretic peptide levels, and two-dimensional echocardiography were also performed. Four (57%) of the seven carriers had LGE, and LGE was frequently observed at the subepicardial layer in the inferolateral segment. Two carriers had a focal LGE at the LV inferolateral wall without LV dilation or wall motion abnormalities.

CONCLUSION

CMR findings of DMD carriers were characterised by subepicardial LGE, which was localised at inferolateral segments. CMR may be a useful modality for detecting cardiac involvement in DMD carriers.

Adherence to american academy of pediatrics recommendations for cardiac care among female carriers of duchenne and becker muscular dystrophy

OBJECTIVE

The goal was to assess women's knowledge and heart health behaviors consistent with the American Academy of Pediatrics recommendations for cardiac care among female carriers of Duchenne/Becker muscular dystrophy.

METHODS

Using an advocacy group mailing list and working with 50 Muscular Dystrophy Association clinics, we surveyed women who had given birth to a son with Duchenne/Becker muscular dystrophy, thought that they were definitely or probably (>/=50% likelihood) a Duchenne/Becker muscular dystrophy carrier, or both. Self-report data classified respondents as carriers, noncarriers, or women with unknown status.

RESULTS

The respondents included 833 Duchenne/Becker muscular dystrophy carriers, 376 noncarriers, and 192 women with unknown status. Carriers were more likely than noncarriers and women in the unknown-status group to have ever undergone electrocardiography or other heart testing and to have seen a cardiologist in the past year, but they were not more likely to report a recent blood pressure or cholesterol level check. Only 64.4% of the carriers had ever had a heart test; 18.3% had seen a cardiologist in the past year. Only 62.9% of the carriers were aware of their cardiomyopathy risks before participating in the survey; 69.3% had informed their health care provider of their carrier status. Among carriers who had informed their provider, 70.2% had ever had a heart test and 21.4% had seen a cardiologist in the past year. In adjusted logistic regression models, factors that significantly increased the likelihood among carriers of ever having had a heart test and seeing a cardiologist in the previous year included older age (>/=50 years), feeling informed about their cardiomyopathy risks before the survey, and having told their provider about their carrier status.

CONCLUSION

More health education efforts are needed for both patients and their providers, to improve adherence to the American Academy of Pediatrics cardiac care guidelines for female Duchenne/Becker muscular dystrophy carriers.