Cardiomyopathy in Non-Ambulatory Patients with Duchenne Muscular Dystrophy: Two Case Reports with Varying Outcomes, Considering Novel Treatments

Abstract

Background and Clinical Significance: Cardiomyopathy is a significant cause of mortality in patients with Duchenne muscular dystrophy (DMD). Key prognostic factors include the age of onset of cardiomyopathy, low body mass index (BMI), and poor respiratory function. Detection of cardiac abnormalities can be challenging, which complicates timely diagnosis and treatment. Common treatments for heart failure include ACE inhibitors, beta-blockers, and mineralocorticoids. However, their effectiveness can vary, and the progression of cardiomyopathy may differ from one patient to another. Ongoing research aims to identify better therapeutic strategies and biomarkers for early intervention, ultimately improving the quality of life for patients affected by cardiomyopathy. New medications for heart failure, such as sodium/glucose co-transporter 2 inhibitors (SGLT2i) and valsartan/sacubitril (V/S), have been proposed, but their safety and efficacy in DMD patients remain unknown. Case Presentation: We present two cases that illustrate the histories of two patients who experienced different outcomes. The management of the first patient was complicated by several factors, including an early onset of cardiomyopathy, intolerance to ACE inhibitors, and untreated scoliosis, which hindered the implantation of a cardioverter defibrillator (ICD). Unfortunately, he only benefited from dapagliflozin in the later stages of his cardiomyopathy. Neurological complications further exacerbated the advanced state of his disease. In contrast, the second patient adhered to all recommended therapies, including innovative medications, and he currently has compensated heart failure. Conclusions: We concluded that several factors, beyond genetic ones, may have influenced their prognosis, including updated guidelines for cardiomyopathy treatment and the utilization of innovative medications.

Keywords: Duchenne muscular dystrophy; cardiomyopathy; congestive heart failure; echocardiogram; left ventricular ejection fraction.

Figure 1

Parasternal M-mode view shows internal dimensions of dilated left ventricle with reduced ejection fraction (EF about 35%). A: End Diastolic Diameter=60 mm; B: End Systolic Diameter=44 mm, Fractional Shortening = 26%).

Figure 2

Cardiac magnetic resonance four-chamber view. Late gadolinium enhancement in the left ventricle wall (arrows) in a typical non-ischemic (mid-wall) distribution, due to extensive myocardial fibrosis.

Figure 3

Percentage distribution of various treatments in our patients diagnosed with DMD and cardiomyopathy. ICD, implantable cardioverter defibrillator; MRA, mineralocorticoid receptor antagonists.