Non-ischemic Cardiomyopathies - Cases

1351657 - Duchenne Muscular Dystrophy Cardiomyopathy in a 21-year-old Male

Friday, January 27, 2023

7:00 AM – 7:50 AM

Location: Pacific Jewel

Presenting Author(s)

RB

Robyn Bryde, MD

Cardiology Fellow
Mayo Clinic
Jacksonville, Florida, United States

Primary Author(s)

RB

Robyn Bryde, MD

Cardiology Fellow
Mayo Clinic
Jacksonville, Florida, United States

Co-Author(s)

BC

Bryan Cannon, MD

Professor of Medicine
Mayo Clinic, United States
JB

John Bois, MD

Associate Professor of Medicine
Mayo Clinic, United States
PA

Phillip Araoz, MD

Professor of Radiology
Mayo Clinic, United States

Description of Clinical Presentation: A 21-year-old male patient with a history of Duchenne muscular dystrophy (DMD) diagnosed at age six presented to our institution for heart failure treatment considerations at the discretion of his local cardiologist. His ejection fraction was previously measured at 30% by transthoracic echocardiogram (TTE) and he was currently without heart failure symptoms. Cardiac medications included carvedilol 3.215 mg bid, enalapril 15 mg daily, furosemide 20 mg daily, and spironolactone 25 mg daily. As part of his continued workup for DMD, cardiac magnetic resonance (CMR) imaging was obtained to evaluate for DMD related cardiomyopathy.

Diagnostic Techniques and Their Most Important Findings:

A CMR with and without contrast revealed severe LV enlargement with severely reduced global systolic function (LVEF 19%). There was marked thinning and dyskinesis of the lateral wall at the mid ventricle and base with transmural delayed enhancement consistent with fibrosis. Moderate-severe central mitral valve regurgitation secondary to LV enlargement was noted.

Based on CMR findings, the decision was made to optimize medical therapy and forgo cardiac resynchronization therapy (CRT) at that time.

Learning Points from this Case:

Muscular dystrophies are known to have many cardiac manifestations including heart failure, arrhythmia, and conduction abnormalities. The mechanism of DMD causing cardiac dysfunction is due to dysfunctional sarcolemma proteins found in skeletal and cardiac muscle which are essential in maintaining structural and functional integrity by connecting the cytoskeleton the extracellular matrix. CMR is the gold standard to assess ventricular size and function when compared to TTE and has the added benefit of tissue characterization with administration of contrast agents. Gadolinium-based contrast agents help identify myocardial fibrosis which signifies cardiomyocyte damage and cell loss. Patients with DMD more commonly have extensive LGE involving the lateral wall and this is associated with a higher incidence of arrhythmia and death. When considering additional heart failure therapies such as CRT, CMR is helpful in locating the size and location of scarred myocardium as extensive scar size, particularly when involving the posterior-lateral wall, is a strong predictor of nonresponse and worse outcomes following CRT.

CMR was helpful in our patient to confirm the presence of a non-ischemic cardiomyopathy with a significant amount of transmural fibrosis involving the lateral wall, a finding commonly seen in DMD cardiomyopathy. The presence of severe transmural lateral wall scarring with minimal functional contraction would likely result in failure of CRT in this patient and therefore the decision was made to optimize medical therapy with close follow-up.