A case series of desmoplakin cardiomyopathy: a mimic of viral myocarditis.

Background: Clinical features and imaging presentation of myocarditis can overlap with other inflammatory or arrhythmogenic cardiomyopathies. Desmoplakin (DSP) is an important structural cardiac protein. Mutations in the DSP gene are associated with a variant of arrhythmogenic right ventricular cardiomyopathy (ARVC). Interestingly, this distinct genetic cardiomyopathy can also present with a myocardial inflammation and fibrosis pattern that may mimic other forms of myocarditis including viral myocarditis, which can raise a clinical challenge. We report two cases of DSP cardiomyopathy, which were initially thought to represent coronavirus disease of 2019 (COVID-19) myocarditis. Case summary: First patient is a 21-your-old woman with no past medical history but family history of presumed 'viral myocarditis' and ventricular tachycardia in her brother. She presented with acute chest pain and elevated cardiac enzymes. She tested positive for COVID-19 and given the suspicion for possible COVID-19 related acute myocarditis, cardiac magnetic resonance imaging obtained and revealed regional wall motion abnormalities, several areas of subepicardial and pericardial late gadolinium enhancement (LGE). Ambulatory cardiac monitoring showed runs of non-sustained ventricular tachycardia and considering her family history of arrhythmogenic myocarditis, genetic testing was performed that was positive for a likely pathogenic heterozygous mutation of DSP gene. She declined the recommended implantable cardioverter defibrillator (ICD).Second patient is a 34-year-old physician with no significant past medical history who works at a COVID-19 unit and presented with syncope and was found to have ventricular tachycardia. Echocardiogram revealed severely dilated left ventricle and globally depressed systolic function with left ventricular ejection fraction of 20%. Coronary computed tomography angiography showed no evidence of coronary atherosclerosis. Cardiac magnetic resonance imaging revealed several areas of mid myocardial and pericardial LGE. Subcutaneous ICD was implanted and an endomyocardial biopsy had evidence of lymphocytic myocarditis and adipose tissue infiltration of the myocardium. Genetic testing revealed pathogenic heterozygous DSP mutation. He underwent epicardial ablation for the episodes of ventricular tachycardia despite medical therapy. He was able to return to work and has not had any further episodes of arrhythmia. Conclusion: Mutations in the DSP gene are associated with left dominant arrhythmogenic cardiomyopathy, which is a variant of ARVC. Beside left ventricular systolic dysfunction and ventricular tachyarrhythmias, carriers of these mutations may present with episodes of chest pain associated with elevated cardiac enzymes and cardiac imaging findings indistinguishable from other forms of acute myocarditis including viral myocarditis. Currently, there are no guidelines for diagnosis and treatment of this entity.