Clinical profiles and prognosis of acute heart failure in adult patients with dystrophinopathies on home mechanical ventilation

Draft Guidance for Industry Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, and Related Dystrophinopathies - Developing Potential Treatments for the Entire Spectrum of Disease

Background

Duchenne muscular dystrophy (DMD) and related dystrophinopathies are neuromuscular conditions with great unmet medical needs that require the development of effective medical treatments.

Objective

To aid sponsors in clinical development of drugs and therapeutic biological products for treating DMD across the disease spectrum by integrating advancements, patient registries, natural history studies, and more into a comprehensive guidance.

Methods

This guidance emerged from collaboration between the FDA, the Duchenne community, and industry stakeholders. It entailed a structured approach, involving multiple committees and boards. From its inception in 2014, the guidance underwent revisions incorporating insights from gene therapy studies, cardiac function research, and innovative clinical trial designs.

Results

The guidance provides a deeper understanding of DMD and its variants, focusing on patient engagement, diagnostic criteria, natural history, biomarkers, and clinical trials. It underscores patient-focused drug development, the significance of dystrophin as a biomarker, and the pivotal role of magnetic resonance imaging in assessing disease progression. Additionally, the guidance addresses cardiomyopathy's prominence in DMD and the burgeoning field of gene therapy.

Conclusions

The updated guidance offers a comprehensive understanding of DMD, emphasizing patient-centric approaches, innovative trial designs, and the importance of biomarkers. The focus on cardiomyopathy and gene therapy signifies the evolving realm of DMD research. It acts as a crucial roadmap for sponsors, potentially leading to improved treatments for DMD.

Advances in Dystrophinopathy Diagnosis and Therapy

Dystrophinopathies are x-linked muscular disorders which emerge from mutations in the Dystrophin gene, including Duchenne and Becker muscular dystrophy, and dilated cardiomyopathy. However, Duchenne muscular dystrophy interconnects with bone loss and osteoporosis, which are exacerbated by glucocorticoids therapy. Procedures for diagnosing dystrophinopathies include creatine kinase assay, haplotype analysis, Southern blot analysis, immunological analysis, multiplex PCR, multiplex ligation-dependent probe amplification, Sanger DNA sequencing, and next generation DNA sequencing. Pharmacological therapy for dystrophinopathies comprises glucocorticoids (prednisone, prednisolone, and deflazacort), vamorolone, and ataluren. However, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and β-blockers are the first-line to prevent dilated cardiomyopathy in dystrophinopathy patients. Duchenne muscular dystrophy gene therapy strategies involve gene transfer, exon skipping, exon reframing, and CRISPR gene editing. Eteplirsen, an antisense-oligonucleotide drug for skipping exon 51 from the Dystrophin gene, is available on the market, which may help up to 14% of Duchenne muscular dystrophy patients. There are various FDA-approved exon skipping drugs including ExonDys-51 for exon 51, VyonDys-53 and Viltolarsen for exon 53 and AmonDys-45 for exon 45 skipping. Other antisense oligonucleotide drugs in the pipeline include casimersen for exon 45, suvodirsen for exon 51, and golodirsen for exon 53 skipping. Advances in the diagnosis and therapy of dystrophinopathies offer new perspectives for their early discovery and care.

Initial multicenter experience with ventricular assist devices in children and young adults with muscular dystrophy: An ACTION registry analysis

PURPOSE

Cardiac disease results in significant morbidity and mortality in patients with muscular dystrophy (MD). Single centers have reported their ventricular assist device (VAD) experience in specific MDs and in limited numbers. This study sought to describe the outcomes associated with VAD therapy in an unselected population across multiple centers.

METHODS

We examined outcomes of patients with MD and dilated cardiomyopathy implanted with a VAD at Advanced Cardiac Therapies Improving Outcomes Network (ACTION) centers from 9/2012 to 9/2020.

RESULTS

A total of 19 VADs were implanted in 18 patients across 12 sites. The majority of patients had dystrophinopathy (66%) and the median age at implant was 17.2 years (range 11.7-29.5). Eleven patients were non-ambulatory (61%) and 6 (33%) were on respiratory support pre-VAD. Five (28%) patients were implanted as a bridge to transplant, 4 of whom survived to transplant. Of 13 patients implanted as bridge to decision or destination therapy, 77% were alive at 1 year and 69% at 2 years. The overall frequencies of positive outcome (transplanted or alive on device) at 1 year and 2 years were 84% and 78%, respectively. Two patients suffered a stroke, 2 developed sepsis, 1 required tracheostomy, and 1 experienced severe right heart failure requiring right-sided VAD.

CONCLUSIONS

This study demonstrates the potential utility of VAD therapies in patients with muscular dystrophy. Further research is needed to further improve outcomes and better determine which patients may benefit most from VAD therapy in terms of survival and quality of life.

Emergency department care of patients with Duchenne muscular dystrophy

Patients with Duchenne muscular dystrophy are living longer and are increasingly seen in Emergency Departments. Though the most common cause of death remains progressive respiratory failure, increased life expectancies have unmasked the significance of progressive myocardial dysfunction, now associated with nearly 40% of mortalities in the DMD population. Cardiac complications such as arrhythmias and cardiomyopathy are becoming ever more widely recognized. Emergency physicians may encounter DMD patients with untreated, undiagnosed or worsening of known heart disease. This review will initially familiarize the emergency physician with the pathophysiology and lifetime trajectory of care for these patients before describing specific emergency department evaluation and treatment.

The impact of genotype on outcomes in individuals with Duchenne muscular dystrophy: A systematic review

Duchenne muscular dystrophy (DMD) is associated with progressive muscle weakness, loss of ambulation (LOA), and early mortality. In this review we have synthesized published data on the clinical course of DMD by genotype. Using a systematic search implemented in Medline and Embase, 53 articles were identified that describe the clinical course of DMD, with pathogenic variants categorizable by exon skip or stop-codon readthrough amenability and outcomes presented by age. Outcomes described included those related to ambulatory, cardiac, pulmonary, or cognitive function. Estimates of the mean (95% confidence interval) age at LOA ranged from 9.1 (8.7-9.6) years among 90 patients amenable to skipping exon 53 to 11.5 (9.5-13.5) years among three patients amenable to skipping exon 8. Although function worsened with age, the impact of genotype was less clear for other outcomes (eg, forced vital capacity and left ventricular ejection fraction). Understanding the distribution of pathogenic variants is important for studies in DMD, as this research suggests major differences in the natural history of disease. In addition, specific details of the use of key medications, including corticosteroids, antisense oligonucleotides, and cardiac medications, should be reported.

Cardiopulmonary phenotypic variability and discordance in Duchenne muscular dystrophy: Implications for new therapies

Neuromuscular respiratory medicine has traditionally focused on assisted lung ventilation and mucus clearance. These therapies have prolonged survival for patients with Duchenne muscular dystrophy (DMD). However, the field is rapidly evolving in a new direction: it is being revolutionized by molecular and genetic therapies. A good correlation between a patient's dystrophin mutation and his cardiopulmonary phenotype would allow accurate prediction of patient prognosis and would facilitate the design of studies that assess new DMD therapies. Instead, patient prognosis and the design of valid therapeutic studies are complicated by cardiopulmonary phenotypic discordance and variability, by which a notable proportion of DMD patients have unexpectedly good or poor cardiopulmonary function. The likely cause of phenotypic variability and discordance is genetic modifiers. Once the modifiers that affect cardiopulmonary function are better understood, it should be possible to create a personalized genetic profile that accurately predicts the prognosis of each individual DMD patient. This would allow investigators to assess the effect of new therapies in the context of each patient's particular cardiopulmonary natural history. Amplification of beneficial cardiopulmonary genetic modifiers and blocking of detrimental modifiers is a promising strategy for creating new DMD therapies. When patients with chronic respiratory failure are treated with assisted ventilation, cardiac function determines their survival. Therefore, prioritizing new cardiac therapies is most likely to prolong patient survival. By focusing on these topics we aim to move neuromuscular respiratory medicine beyond assisted ventilation and coughing and into the age of translational medicine.

Duchenne Dilated Cardiomyopathy: Cardiac Management from Prevention to Advanced Cardiovascular Therapies

Duchenne muscular dystrophy (DMD) cardiomyopathy (DCM) is characterized by a hypokinetic, dilated phenotype progressively increasing with age. Regular cardiac care is crucial in DMD care. Early recognition and prophylactic use of angiotensin converting enzyme inhibitors (ACEi) are the main stay therapeutic strategy to delay incidence of DMD-DCM. Pharmacological treatment to improve symptoms and left ventricle (LV) systolic function, have been widely implemented in the past years. Because of lack of DMD specific drugs, actual indications for established DCM include current treatment for heart failure (HF). This review focuses on current HF strategies to identify, characterize, and treat DMD-DCM.

Risk factors for hospital readmission of patients with heart failure: A cohort study

Aim:

The aim of this study was to develop a risk factor model for hospital readmission in patients with heart failure.

Background:

Identification of risk factors and predictors of readmission to hospital in patients with heart failure is very crucial for improved clinical outcomes.

Objective:

The objective of the current study was to investigate and delineate the risk factors that may be implicated in putting a patient at greater risk of readmission due to uncontrolled heart failure.

Materials and Methods:

This is a prospective follow-up cohort study of 170 patients with heart failure at a tertiary hospital in Al Ain city in the United Arab Emirates. We have developed a risk factor model based on the recommendations of validated published data. We have used univariate and multivariate logistic regression analyses on structured steps based on the published data. The main outcome was the risk factors for readmission to hospital due to heart failure.

Results:

A final predictive model (10 variables) was produced for unplanned readmission of patients with heart failure. The risk factors identified in the final model with their odds ratios (ORs) and confidence intervals (CIs) were as follows: four or more prescribed medicines (OR = 4.13; CI = 3.5–4.1; P = 0.003), more than twice daily dosing regimen (OR = 2.34; CI = 1.0–5.0; P = 0.023), poor knowledge of prescribed medications (OR = 4.24; CI = 1.213–14.781; P = 0.006), diabetes mellitus (OR = 3.78; CI = 1.6–8.7; P = 0.006), edema (OR = 2.64; CI = 1.2–5.6; P = 0.011), being house bound (OR = 2.77; CI = 1.2–6.2; P = 0.014), and being prescribed diuretics (OR = 3.69; CI = 1.4–9.2; P = 0.042).

Conclusion:

The specificity of the developed risk prediction model was 82.2%, the sensitivity was 74.3%, and the overall accuracy was 72.9%. The model can be emulated in population with similar characteristics to prevent early readmission of patient with heart failure.

Destination-Therapy Ventricular Assist Device in Children: "The Future Is Now"

Durable ventricular assist devices (VADs) have significantly improved survival to transplantation among children with advanced stages of heart failure. The fundamental goals of VAD therapy include decreasing mortality, minimizing adverse events, and improving quality of life. As the pediatric VAD experience has evolved with reduced device related complications and improved survival, VAD therapy is being considered not only as a bridge to transplantation (BTT) but also as a bridge to decision (BTD) and as destination therapy (DT). Data regarding pediatric DT VAD are limited to anecdotal or case reports of children being supported for long periods with VADs and by default being classified as DT VAD. This article reviews current trends in the use of DT VAD and adverse events in children vs adults on VAD, and provides a framework for patient selection with the use of a multidisciplinary approach including palliative care. The general approach to determining DT VAD candidacy should include: 1) a reasonable success that the patient will survive the peri- and postoperative state; and 2) a high likelihood that the patient will be able to be discharged out of hospital and have adequate caregiver support. Patients with muscular dystrophy and failing Fontan physiology are examples of pediatric populations for whom DT VAD may be considered and which require unique considerations.

Accuracy of B-natriuretic peptide for the diagnosis of decompensated heart failure in muscular dystrophies patients with chronic respiratory failure

Heart failure and restrictive respiratory insufficiency are complications in muscular dystrophies. We aimed to assess the accuracy of the B-natriuretic peptide (BNP) for the diagnosis of decompensated heart failure in muscular dystrophy. We included patients with muscular dystrophy and chronic respiratory insufficiency admitted in the Intensive Care Unit of the Raymond Poincare hospital (Garches, France) for suspected decompensated heart failure. Thirtyseven patients were included, among them, 23 Duchenne muscular dystrophy (DMD) (62%), 10 myotonic dystrophy type 1(DM1) (27%). Median age was 35 years [27.5; 48.5]. 86.5% of patients were on home mechanical ventilation (HMV). Median left ventricular ejection fraction (LVEF) was 47% [35.0; 59.5]. Median BNP blood level was 104 pg/mL [50; 399]. The BNP level was significantly inversely associated with LVEF (r= –0.37, p 0.03) and positively associated with the LVEDD (left ventricular end diastolic diameter) (r=0.59, P<0.001). The discriminative value of the BNP level for the diagnosis of decompensated heart failure was high with an AUROC=0.94 (P<0.001). The best discriminating BNP threshold was 307 pg/mL (Youden index 0.85).

The BNP level measurement may add a supplemental key for the final diagnosis of decompensated heart failure.

Clinical profiles and prognosis of acute heart failure in adult patients with dystrophinopathies on home mechanical ventilation

Aims

Duchenne muscular dystrophy (DMD) is characterized by respiratory and heart involvements. In the context of permanently wheelchair bound and on mechanical ventilation (MV) patients, the clinical presentation of acute heart failure (AHF) syndrome may be atypical. We sought to describe clinical and genetic profiles and to determine prognosis of DMD and Becker muscular dystrophy (BMD) patients on home MV (HMV), hospitalized for AHF.

Methods and results

We included genetically proven DMD and BMD patients on HMV admitted for AHF. A total of 13 patients (11 DMD and 2 BMD) fulfilled the inclusion criteria. Median age was 34.0 [interquartile range (IQR) 26.0; 40.0] years. Median pulmonary vital capacity was 9.0% (6.0; 15.0) of predicted value. Long‐term invasive ventilation was performed in 69% of patients. All the 11 DMD patients carried out‐of‐frame DMD gene mutations. At admission, dyspnoea was present in 46%, lipothymia in 23%, and abdominal discomfort in 38.4% of patients. A total of 53.8% of patients showed anasarca. Cardiogenic shock presentation was found in six patients (46%). Ejection fraction was severely altered [median 25% (IQR 20; 30)]. Intra‐hospital mortality rate was 30%, reaching 53.8 % after 1 year. Previous episodes of AHF ≥ 2 were associated with intra‐hospital mortality (P = 0.025). In patients with cardiogenic shock, intra‐hospital mortality rate was 66.6%, reaching 83.3% after 1 year.

Conclusions

In adult DMD and BMD patients with severe ejection fraction alteration and on HMV, admitted for AHF, right cardiac signs are frequent. The intra‐hospital and 1 year mortality rate was high and was associated with previous episodes of AHF ≥ 2.