Pharmacological therapy for the prevention and management of cardiomyopathy in Duchenne muscular dystrophy: A systematic review

Is Cardiac Transplantation Still a Contraindication in Patients with Muscular Dystrophy-Related End-Stage Dilated Cardiomyopathy? A Systematic Review

Inherited muscular diseases (MDs) are genetic degenerative disorders typically caused by mutations in a single gene that affect striated muscle and result in progressive weakness and wasting in affected individuals. Cardiac muscle can also be involved with some variability that depends on the genetic basis of the MD (Muscular Dystrophy) phenotype. Heart involvement can manifest with two main clinical pictures: left ventricular systolic dysfunction with evolution towards dilated cardiomyopathy and refractory heart failure, or the presence of conduction system defects and serious life-threatening ventricular arrhythmias. The two pictures can coexist. In these cases, heart transplantation (HTx) is considered the most appropriate option in patients who are not responders to the optimized standard therapeutic protocols. However, cardiac transplant is still considered a relative contraindication in patients with inherited muscle disorders and end-stage cardiomyopathies. High operative risk related to muscle impairment and potential graft involvement secondary to the underlying myopathy have been the two main reasons implicated in the generalized reluctance to consider cardiac transplant as a viable option. We report an overview of cardiac involvement in MDs and its possible association with the underlying molecular defect, as well as a systematic review of HTx outcomes in patients with MD-related end-stage dilated cardiomyopathy, published so far in the literature.

Abbreviated cardiac magnetic resonance imaging versus echocardiography for interval assessment of systolic function in Duchenne muscular dystrophy: patient satisfaction, clinical utility, and image quality

PURPOSE

Poor acoustic windows make interval assessment of systolic function in patients with (Duchenne Muscular Dystrophy) DMD by echocardiography (echo) difficult. Cardiac magnetic resonance imaging (CMR) can be challenging in DMD patients due to study duration and patient discomfort. We developed an abbreviated CMR (aCMR) protocol and hypothesized that aCMR would compare favorably to echo in image quality and clinical utility without significant differences in exam duration, patient satisfaction, and functional measurements.

METHODS

DMD patients were recruited prospectively to undergo echo and aCMR. Modalities were compared with a global quality assessment score (GQAS), clinical utility score (CUS), and patient satisfaction score (PSS). Results were compared using Wilcoxon signed-rank tests, Spearman correlations, intraclass correlations, and Bland-Altman analyses.

RESULTS

Nineteen DMD patients were included. PSS scores and exam duration were equivalent between modalities, while CUS and GQAS scores favored aCMR. ACMR scored markedly higher than echo in RV visualization and assessment of atrial size. Older age was negatively correlated with echo GQAS and CUS scores, as well as aCMR PSS scores. Higher BMI was positively correlated with aCMR GQAS scores. Nighttime PPV requirement and non-ambulatory status were correlated with worse echo CUS scores. Poor image quality precluding quantification existed in five (26%) echo and zero (0%) aCMR studies. There was moderate correlation between aCMR and echo for global circumferential strain and left ventricular four chamber global longitudinal strain.

CONCLUSION

The aCMR protocol resulted in improved clinical relevance and quality scores relative to echo, without significant detriment to patient satisfaction or exam duration.

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

INTRODUCTION

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

Jumping Mechanography is a Suitable Complementary Method to Assess Motor Function in Ambulatory Boys with Duchenne Muscular Dystrophy

OBJECTIVE

The number of clinical trials for Duchenne muscular dystrophy (DMD) has increased substantially lately, therefore appropriate clinical instruments are needed to measure disease progression and drug efficacy. Jumping mechanography is a medical diagnostic method for motion analysis, which allows to quantify physical parameters. In this study, we compared mechanography with timed function tests (TFTs).

METHODS

41 ambulatory DMD patients performed a total of 95 chair rising tests (CRT) and a total of 76 single two-legged jumps (S2LJ) on a mechanography ground reaction force platform. The results were correlated with a 6-minute walk test (6MWT) and the time required to run 10 meters, stand up from a supine position, and climb four stairs, all performed in the same setting.

RESULTS

Our measurements show a high correlation between mechanography and the TFTs: S2LJ/10-m run, r = 0.62; CRT/10-m run, r = 0.61; S2LJ/standing up from supine, r = 0.48; CRT/standing up from supine, r = 0.58; S2LJ/climb four stairs, r = 0.55; CRT/climb four stairs, r = 0.51. The correlation between mechanography and the 6MWT was only moderate with r = 0.38 for S2LJ/6MWT and r = 0.39 for CRT/6MWT.

INTERPRETATION

Jumping mechanography is a reliable additional method, which can be used for physical endpoint measurements in clinical trials. We confirmed our assumption, that the method provides additional information concerning performance at movement with higher power output. We suggest using the S2LJ as a first-choice tandem tool combined with the 6MWT. In patients with higher disability, the CRT is an alternative measuring method, because with the progression of the disease this is longer feasible.

Becker muscular dystrophy: case report, review of the literature, and analysis of differentially expressed hub genes

INTRODUCTION

Becker muscular dystrophy (BMD) is a genetic and progressive neuromuscular disease caused by mutations in the dystrophin gene with no available cure. A case report and comprehensive review of BMD cases aim to provide important clues for early diagnosis and implications for clinical practice. Genes and pathways identified from microarray data of muscle samples from patients with BMD help uncover the potential mechanism and provide novel therapeutic targets for dystrophin-deficient muscular dystrophies.

METHODS

We describe a BMD family with a 10-year-old boy as the proband and reviewed BMD cases from PubMed. Datasets from the Gene Expression Omnibus database were downloaded and integrated with the online software.

RESULTS

The systematic review revealed the clinical manifestations and mutation points of the dystrophin gene. Gene ontology analysis showed that extracellular matrix organization and extracellular structure organization with enrichment of upregulated genes coexist in three datasets. We present the first report of TUBA1A involvement in the development of BMD/Duchenne muscular dystrophy (DMD).

DISCUSSION

This study provides important implications for clinical practice, uncovering the potential mechanism of the progress of BMD/DMD, and provided new therapeutic targets.

A systematic review of pharmacologic therapies for the cardiomyopathy of Duchenne muscular dystrophy

OBJECTIVE

To perform a systematic review of studies evaluating pharmacologic therapies for the cardiomyopathy of Duchenne muscular dystrophy (DMD).

METHODS

PubMed, Google Scholar, and Embase were searched through October 8, 2020. Articles were selected using pre-determined criteria; 26 underwent detailed review by two co-authors. Study quality was assessed with the Newcastle-Ottawa scoring system (NOS); GRADE assessment evaluated their overall clinical importance.

RESULTS

There were few randomized controlled trials. Two of four trials of angiotensin converting enzyme inhibitors (ACEI) or ACEI plus beta-blockers (BB) found improved LV function. Two of two randomized trials of aldosterone antagonists (AA), when added to ACEI and BB therapy, demonstrated less decline of LV circumferential strain over 1 year of treatment. Observational studies of ACEI and BB had differing patient ages, symptomatology, cohort size, study duration and baseline heart function. LV function, assessed via unblinded imaging, was the most frequent outcome measure. LV dysfunction improved in some trials but was unconfirmed in others. Class IV heart failure patients had transient improvement of symptoms and LVEF. Most NOS scores reflected a low level of study quality. The Grade certainty rating, used for the summation of studies, was between "low" and "moderate."

CONCLUSION

Randomized trial evidence was inconsistent that either ACEI or BB or their combination improve LV function and/or alter progressive LV dysfunction. When ACEI and BB therapy are initiated for symptomatic Class IV heart failure, symptoms and LVEF improve transiently. AAs retard the rate of decline of LV function when initiated in younger DMD patients.

New Therapeutics Options for Pediatric Neuromuscular Disorders

Neuromuscular disorders (NMDs) of Childhood onset are a genetically heterogeneous group of diseases affecting the anterior horn cell, the peripheral nerve, the neuromuscular junction, or the muscle. For many decades, treatment of NMDs has been exclusively symptomatic. But this has changed fundamentally in recent years due to the development of new drugs attempting either to ameliorate secondary pathophysiologic consequences or to modify the underlying genetic defect itself. While the effects on the course of disease are still modest in some NMDs (e.g., Duchenne muscular dystrophy), new therapies have substantially prolonged life expectancy and improved motor function in others (e.g., spinal muscular atrophy and infantile onset Pompe disease). This review summarizes recently approved medicaments and provides an outlook for new therapies that are on the horizon in this field.

Is It Possible for Children in Duchenne Muscular Dystrophy to Preserve Cardiac Function with Medical Assistance?

In patients with Duchenne muscular dystrophy (DMD), death secondary to cardiac or respiratory failure typically occurs in the second or third decade without treatment. Although cardiac dysfunction is treated with standard heart-failure strategies, it remains insufficient in DMD children. The purpose of this study was to evaluate the efficiency of cardiac medication and noninvasive ventilator support in DMD cardiomyopathy children with analyzing echocardiographic data. Forty-eight DMD children patients were included and divided into 2 groups by left ventricular (LV) ejection fraction (EF) at the time of initial treatment. Group 1: LV EF ≥ 45% and Group 2: LV EF < 45%. p-values were calculated using a Linear mixed model to estimate the association between cardiac medications and echocardiographic measurements. Before and after cardiac medications, the change values were significantly different in interventricular septal thickness at end diastole (IVSd), interventricular septal thickness at end systole (IVSs), left ventricular internal diameter end systole (LVIDs), left ventricular posterior wall thickness end diastole (LVPWd), ejection fraction (EF), fractional shortening (FS), deceleration time (DT), DT slope, Lat A’ and Lat E/E’ (p < 0.05). Group 2 patients revealed to take more kinds of cardiac medications than Group 1 (p < 0.05) including ACEIs, beta-blocker, and inotropics, then LV EF was better preserved in Group 2 than Group 1. It is certainly helpful to take individualized medical combination therapy including inotropic agents for cardiomyopathy in DMD children patients with EF < 45%.

Is Exercise-Induced Fatigue a Problem in Children with Duchenne Muscular Dystrophy?

OBJECTIVE

Duchenne muscular dystrophy (DMD) is a devastating X-linked muscular disorder. The number of studies investigating new therapeutic approaches is substantially increasing. This study aims to investigate the impact and diagnostic value of exercise-induced fatigue in DMD, which has been proposed as a suitable outcome parameter in other conditions like spinal muscular atrophy.

PATIENTS AND METHODS

A cohort of 55 DMD patients (49 of them treated with steroids and 9 with ataluren) underwent a total of 241 6MWT (mean 4.4 tests/patient) which were retrospectively analyzed. Exercise-induced fatigue was assessed by the ratio between the distance achieved in the sixth minute and the distance in the second minute of the 6MWT. In previous studies a quotient above 1 was defined as a sign of fatigue.

RESULTS

The average fatigue quotient in the whole cohort of patients was 1.0. In a further analysis no impact of age, steroid therapy, ataluren therapy, overall disability, and distance in the 6-minute walk test (6MWT) on fatigue in DMD patients could be shown.

CONCLUSION

Our data show that fatigue does not play a relevant role in DMD. Analysis of fatigue is not a useful outcome parameter in DMD studies. For this reason we suggest the 2MWT, which is better accepted by the patients, as an alternative to the commonly 6MWT.

Apocynin Treatment Prevents Cardiac Connexin 43 Hemichannels Hyperactivity by Reducing Nitroso-Redox Stress in Mdx Mice

Duchenne muscular dystrophy (DMD) is a fatal disease that causes cardiomyopathy and is associated with oxidative stress. In the heart, oxidative stress interferes with the location of connexin 43 (Cx43) to the intercalated discs causing its lateralization to the plasma membrane where Cx43 forms hemichannels. We tested the hypothesis that in DMD cardiomyopathy, increased oxidative stress is associated with the formation and activation of Cx43 hemichannels. For this, we used mdx mice as a DMD model and evaluated cardiac function, nitroso-redox changes and Cx43 hemichannels permeability. Mdx hearts presented increased NADPH oxidase-derived oxidative stress and increased Cx43 S-nitrosylation compared to controls. These redox changes were associated with increased Cx43 lateralization, decreased cardiac contractility and increased arrhythmic events. Pharmacological inhibition of NADPH oxidase using apocynin (one month) reduced systemic oxidative stress and reversed the aforementioned changes towards normal, except Cx43 lateralization. Opening of Cx43 hemichannels was blocked by apocynin treatment and by acute hemichannel blockade with carbenoxolone. NADPH oxidase inhibition also prevented the occurrence of apoptosis in mdx hearts and reversed the ventricular remodeling. These results show that NADPH oxidase activity in DMD is associated with S-nitrosylation and opening of Cx43 hemichannels. These changes lead to apoptosis and cardiac dysfunction and were prevented by NADPH oxidase inhibition.

Recurrent hypotension induced by sacubitril/valsartan in cardiomyopathy secondary to Duchenne muscular dystrophy: A case report

BACKGROUND

Duchenne muscular dystrophy (DMD), which is caused by a mutation/deletion in the dystrophin gene on the X-chromosome, is the most common type of neuromuscular disorder in pediatrics. Skeletal muscle weakness progressively develops in DMD patients and usually leads to respiratory failure in the early adolescent years. Cardiac muscle is frequently affected in DMD patients, which leads to a high burden of cardiomyopathy and heart failure. In the era of improved respiratory care, cardiac deaths are becoming the major cause of mortality in DMD patients.

CASE SUMMARY

We report the case of a 15-year-old boy who presented to the hospital due to recurrent orthopnea for 6 mo and palpitations for 4 mo. He was diagnosed with progressive muscular dystrophy at the age of 3 years and was confined to a wheelchair at 12 years. He was prescribed diuretics and digoxin at the outpatient clinic; however, his symptoms did not resolve. Sacubitril/valsartan was added 1 mo prior to presentation, but he experienced recurrent episodes of palpitations. The electrocardiogram showed atrial tachycardia with a heart rate of 201 bpm, and he was then hospitalized. Hypotension was found following the administration of sacubitril/valsartan tablets; he could not tolerate even a small dose, always developing tachyarrhythmia. His symptoms were relieved after discontinuing sacubitril/valsartan, and his heart rate was controlled by a small dose of metoprolol tartrate and digoxin. Atrial tachycardia spontaneously converted in this patient, and his symptoms attenuated in the following 6 mo, without palpitation episodes.

CONCLUSION

Blood pressure should be closely monitored in DMD patients with advanced heart failure when taking sacubitril/valsartan.

Renal dysfunction can occur in advanced-stage Duchenne muscular dystrophy

INTRODUCTION

With improved treatments, patients with Duchenne muscular dystrophy (DMD) can survive far beyond adolescence. However, advanced-stage DMD patients are at risk of developing renal dysfunction. In this study, long-term renal function outcomes and associated risk factors in advanced stage DMD were analyzed.

METHODS

Fifty-one patients were classified into three different age groups (<20, 20-29, and ≥30 years of age), and cystatin C (CysC) levels were compared among groups.

RESULTS

Median serum CysC levels were 0.74 mg/L, 0.63 mg/L, and 0.76 mg/L in the age groups of <20, 20-29, and ≥30 years, respectively (P = .003). Five of the nine patients in the ≥30 years age group showed elevated serum CysC and decreased cardiac function compared with the other four in the group (P = .014).

DISCUSSION

Our results indicate an association between cardiac and renal dysfunction in patients with advanced-stage DMD.

Effect and safety of treatment with ACE-inhibitor Enalapril and β-blocker metoprolol on the onset of left ventricular dysfunction in Duchenne muscular dystrophy - a randomized, double-blind, placebo-controlled trial

BACKGROUND

X-linked Duchenne muscular dystrophy (DMD), the most frequent human hereditary skeletal muscle myopathy, inevitably leads to progressive dilated cardiomyopathy. We assessed the effect and safety of a combined treatment with the ACE-inhibitor enalapril and the β-blocker metoprolol in a German cohort of infantile and juvenile DMD patients with preserved left ventricular function.

METHODS TRIAL DESIGN

Sixteen weeks single-arm open run-in therapy with enalapril and metoprolol followed by a two-arm 1:1 randomized double-blind placebo-controlled treatment in a multicenter setting.

INCLUSION CRITERIA

DMD boys aged 10-14 years with left ventricular fractional shortening [LV-FS] ≥ 30% in echocardiography. Primary endpoint: time from randomization to first occurrence of LV-FS < 28%. Secondary: changes of a) LV-FS from baseline, b) blood pressure, c), heart rate and autonomic function in ECG and Holter-ECG, e) cardiac biomarkers and neurohumeral serum parameters, f) quality of life, and g) adverse events.

RESULTS

From 3/2010 to 12/2013, 38 patients from 10 sites were centrally randomized after run-in, with 21 patients continuing enalapril and metoprolol medication and 17 patients receiving placebo. Until end of study 12/2015, LV-FS < 28% was reached in 6/21 versus 7/17 patients. Cox regression adjusted for LV-FS after run-in showed a statistically non-significant benefit for medication over placebo (hazard ratio: 0.38; 95% confidence interval: 0.12 to 1.22; p = 0.10). Analysis of secondary outcome measures revealed a time-dependent deterioration of LV-FS with no statistically significant differences between the two study arms. Blood pressure, maximal heart rate and mean-NN values were significantly lower at the end of open run-in treatment compared to baseline. Outcome analysis 19 months after randomization displayed significantly lower maximum heart rate and higher noradrenalin and renin values in the intervention group. No difference between treatments was seen for quality of life. As a single, yet important adverse event, the reversible deterioration of walking abilities of one DMD patient during the run-in period was observed.

CONCLUSIONS

Our analysis of enalapril and metoprolol treatment in DMD patients with preserved left ventricular function is suggestive to delay the progression of the intrinsic cardiomyopathy to left ventricular failure, but did not reach statistical significance, probably due to insufficient sample size.

CLINICAL TRIAL REGISTRATION

DRKS-number 00000115, EudraCT-number 2009-009871-36.

Clinical management of Duchenne muscular dystrophy: the state of the art

INTRODUCTION

Duchenne muscular dystrophy (DMD) is a devastating, progressive neuromuscular disorder for which there is no cure. As the dystrophin gene is located on the X chromosome, DMD occurs predominately in males. DMD is caused by a lack of functional dystrophin protein resulting from mutations in the 2.2-Mb DMD gene, whichdisrupts the reading frame. Care considerations for DMD advocate a coordinated, multidisciplinary approach to the management of DMD in order to optimize management of the primary manifestations of DMD as well as any secondary complications that may arise.

METHODS

This review provides an overview of the multidisciplinary clinical management of DMD with regard to the respiratory, cardiology, orthopedic, and nutritional needs of patients with DMD. Recent advances in novel disease-modifying treatments for DMD are also discussed with specific reference to exon skipping and suppression of premature stop codons as promising genetic therapies.

RESULTS

The combination of multidisciplinary clinical management alongside novel gene therapiesoffers physicians a powerful armamentarium for the treatment of DMD.

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

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

Achievement of Virtual and Real Objects Using a Short-Term Motor Learning Protocol in People with Duchenne Muscular Dystrophy: A Crossover Randomized Controlled Trial

OBJECTIVE

To evaluate whether people with Duchenne muscular dystrophy (DMD) practicing a task in a virtual environment could improve performance given a similar task in a real environment, as well as distinguishing whether there is transference between performing the practice in virtual environment and then a real environment and vice versa.

METHODS

Twenty-two people with DMD were evaluated and divided into two groups. The goal was to reach out and touch a red cube. Group A began with the real task and had to touch a real object, and Group B began with the virtual task and had to reach a virtual object using the Kinect system.

RESULTS

ANOVA showed that all participants decreased the movement time from the first (M = 973 ms) to the last block of acquisition (M = 783 ms) in both virtual and real tasks and motor learning could be inferred by the short-term retention and transfer task (with increasing distance of the target). However, the evaluation of task performance demonstrated that the virtual task provided an inferior performance when compared to the real task in all phases of the study, and there was no effect for sequence.

CONCLUSIONS

Both virtual and real tasks promoted improvement of performance in the acquisition phase, short-term retention, and transfer. However, there was no transference of learning between environments. In conclusion, it is recommended that the use of virtual environments for individuals with DMD needs to be considered carefully.

Gonorazky H, Cohn RD, Campbell C. Treating pediatric neuromuscular disorders: The future is now

Pediatric neuromuscular diseases encompass all disorders with onset in childhood and where the primary area of pathology is in the peripheral nervous system. These conditions are largely genetic in etiology, and only those with a genetic underpinning will be presented in this review. This includes disorders of the anterior horn cell (e.g., spinal muscular atrophy), peripheral nerve (e.g., Charcot-Marie-Tooth disease), the neuromuscular junction (e.g., congenital myasthenic syndrome), and the muscle (myopathies and muscular dystrophies). Historically, pediatric neuromuscular disorders have uniformly been considered to be without treatment possibilities and to have dire prognoses. This perception has gradually changed, starting in part with the discovery and widespread application of corticosteroids for Duchenne muscular dystrophy. At present, several exciting therapeutic avenues are under investigation for a range of conditions, offering the potential for significant improvements in patient morbidities and mortality and, in some cases, curative intervention. In this review, we will present the current state of treatment for the most common pediatric neuromuscular conditions, and detail the treatment strategies with the greatest potential for helping with these devastating diseases.

Cardiac function associated with home ventilator care in Duchenne muscular dystrophy

Purpose

Cardiomyopathy is becoming the leading cause of death in patients with Duchenne muscular dystrophy because mechanically assisted lung ventilation and assisted coughing have helped resolve respiratory complications. To clarify cardiopulmonary function, we compared cardiac function between the home ventilator-assisted and non-ventilator-assisted groups.

Methods

We retrospectively reviewed patients with Duchenne muscular dystrophy from January 2010 to March 2016 at Gangnam Severance Hospital. Demographic characteristics, pulmonary function, and echocardiography data were investigated.

Results

Fifty-four patients with Duchenne muscular dystrophy were divided into 2 groups: home ventilator-assisted and non-ventilator-assisted. The patients in the home ventilator group were older (16.25±1.85 years) than those in the nonventilator group (14.73±1.36 years) (P=0.001). Height, weight, and body surface area did not differ significantly between groups. The home ventilator group had a lower seated functional vital capacity (1,038±620.41 mL) than the nonventilator group (1,455±603.12 mL). Mean left ventricular ejection fraction and fractional shortening were greater in the home ventilator group, but the data did not show any statistical difference. The early ventricular filling velocity/late ventricular filling velocity ratio (1.7±0.44) was lower in the home ventilator group than in the nonventilator group (2.02±0.62). The mitral valve annular systolic velocity was higher in the home ventilator group (estimated β, 1.06; standard error, 0.48). Patients with Duchenne muscular dystrophy on a ventilator may have better systolic and diastolic cardiac functions.

Conclusion

Noninvasive ventilator assistance can help preserve cardiac function. Therefore, early utilization of noninvasive ventilation or oxygen may positively influence cardiac function in patients with Duchenne muscular dystrophy.

Bridging the Gap: An Osteopathic Primary Care–Centered Approach to Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a deadly and incurable disease typically diagnosed in early childhood. Presently, the delay between a caregiver's initial concern and the primary care physician obtaining creatine kinase levels—the most important screening test—is more than a year. It is imperative to diagnose DMD as soon as possible because early treatment has the potential to double the patient's lifespan. In addition, because of geographic and economic disadvantages, multidisciplinary DMD treatment centers are not readily available to all patients. Therefore, the challenge of early diagnosis and treatment coordination rests with the primary care physician. The present review provides osteopathic primary care physicians with current and relevant information regarding DMD diagnosis and management.