Background: Genetic cardiomyopathies (CMP) present with varied phenotypes, including lethal ventricular arrhythmias and/or heart failure.
Objective: We present a vignette and series of patients diagnosed with myocarditis but then found to have genetic cardiomyopathy.
Results: A 21-year-old man was admitted with his third episode of myocarditis over 3 years. He had chest pain and a TnI of 70.6 ng/mL; vital signs and EKG were unremarkable. CMR revealed subepicardial LGE of the LV (LV-LGE) with regional akinesis, lateral LV edema, RVEF=37%, and LVEF=50%. 18FDG-PET showed inferolateral, apical, and septal subepicardial 18FDG uptake suggesting inflammation. Coronary angiography and endomyocardial biopsy were normal. Extensive metabolic and viral testing were unrevealing. FH included myopericarditis in the brother and maternal half-brother, and SCD in the mother and maternal aunt (fifth decade of life). A heterozygous variant in desmoplakin (DSP, c.2794-1G>A) was identified, predicted to disrupt the consensus splice site. ICD was advised but declined. He experienced SCD 6 months later. Additional cases of hereditary CMP presenting as myocarditis are summarized in Table 1.
Conclusion: Patients with desmosomal/sarcomeric gene mutations presenting with chest pain/TnI elevation are at high risk for SCD. It is unclear whether inflammation follows or precedes myocyte necrosis. We hypothesize these mutations predispose to regional myocyte necrosis following exposure to stressors, manifesting as LV-LGE on CMR, and 18FDG uptake by PET. Our series illustrates the importance of FH in patients with recurrent myocarditis and referral for genetic testing for hereditary CMP.