The 'Hot' Phase of a Smoldering Disease: Acute Myocarditis Unmasking Pathogenic Desmoplakin Cardiomyopathy by CMR

Presenting Author(s)

• 

  Ankush Ankush, MD

  Cardiothoracic Imaging Fellow
  Atrium Wake Forest Baptist Medical Center
  Winston Salem, North Carolina, United States

Primary Author(s)

• 

  Ankush Ankush, MD

  Cardiothoracic Imaging Fellow
  Atrium Wake Forest Baptist Medical Center
  Winston Salem, North Carolina, United States

Co-Author(s)

• HG

  HARISH GUDI, MD

  Assistant Professor
  University of Arizona College of Medicine, United States
• ES

  Eswara Sellamuthu, MD

  Assistant Professor
  Atrium Health Wake Forest Baptist Medical Center, United States
• MS

  Muthu Sakthivel, MD, FSCMR

  Assistant Professor/Cardiothoracic Imaging Fellowship Program Director
  UNC School of Medicine
  Chapel Hill, North Carolina, United States
• UJ

  Usha Jayagurunathan, MD

  Assistant Professor
  Atrium Health Wake Forest Baptist Medical Center, United States

Description of Clinical Presentation: A 20-year-old asymptomatic female with a known pathogenic DSP c.250C >T mutation (identified via familial cascade screening after her mother’s sustained VT) presented with exertion-triggered palpitations (HR 200 bpm on Apple Watch) and dull chest pain, resolving spontaneously. Previously managed with metoprolol 25mg for occasional PVCs following genetic diagnosis, she had discontinued competitive swimming. Emergency evaluation revealed normal vitals, unremarkable exam, and no signs of heart failure.

Diagnostic Techniques and Their Most Important Findings: ECG demonstrated frequent PVCs and salvos of right bundle/superior axis ventricular triplets (Figure 1). Telemetry confirmed persistent bigeminy and trigeminy (Figure 2). High-sensitivity troponin peaked at 107 ng/L (normal < 14) with normal NT-proBNP. Echocardiography showed preserved biventricular size, function, and wall motion. Cardiac MRI was pivotal: LVEF was 59%, with new subepicardial T2-weighted edema and early/late gadolinium enhancement (LGE) confined to the basal and mid-ventricular anterolateral and inferolateral segments (< 50% thickness), without RV involvement (Figure 3). This inflammatory zone precisely matched the PVC origin. A symptom-limited exercise test (13 METs) showed no arrhythmia induction. She was discharged on increased metoprolol without recurrence.

Learning Points from this Case: This case uniquely captures the initial clinical manifestation of desmoplakin (DSP) cardiomyopathy mimicking acute myocarditis. DSP mutations cause arrhythmogenic left ventricular cardiomyopathy (ALVC), characterized by subepicardial inflammation/fibrosis—distinct from classic right-dominant arrhythmogenic cardiomyopathy. Our CMR findings (apical inferior subepicardial LGE/edema) align precisely with autopsy and cohort studies describing DSP’s signature pattern: LV-predominant, subepicardial LGE (often inferior/septal/lateral), sparing the RV and subendocardium. The mid-myocardial and subendocardial layer are rarely affected. Additional findings reported in the literature include circumferential late gadolinium enhancement (also described as a “ring-like” scar pattern), presence of intramyocardial fat deposition, localized dilation and hypokinesia, aneurysms. Crucially, this represents the unique instance where acute chest pain, troponin elevation, and PVCs in a young patient with a pathogenic DSP mutation were directly linked to active myocardial inflammation on CMR—confirming the hypothesized mechanism of recurrent injury driving fibrosis and arrhythmia. It underscores that young patients presenting with "myocarditis" and PVCs require urgent CMR and genetic evaluation. Classic CMR patterns like this subepicardial LGE are sentinel markers for DSP cardiomyopathy, enabling early family screening and targeted management before progression to systolic dysfunction or malignant arrhythmias. CMR is indispensable for distinguishing genetic cardiomyopathy from isolated myocarditis in this demographic.

Figure 1: 12-lead ECG showing monomorphic PVCs (arrows) and salvos of ventricular triplets (bracket) of right bundle branch/superior axis morphology.
Figure 2: Telemetry strip demonstrating repetitive bigeminy (PVC every other beat) and trigeminy (PVC every third beat) patterns.
Figure 3: Short-axis LGE-CMR images at basal and mid-ventricular levels revealing focal subepicardial hyperenhancement (yellow arrows) in the inferolateral and anterolateral walls, consistent with active inflammation/fibrosis.