A Diagnostic Dilemma of Arrhythmogenic Cardiomyopathy Masquerading as Recurrent Myocarditis in a Pediatric Patient with a DES Gene Variant: A Case Report

Background: Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder characterized by fibrofatty replacement of cardiomyocytes. The inflammatory episodes of ACM, known as the “hot phase”, can mimic acute myocarditis. It was seldom observed in a DES-associated ACM as a “hot-phase” presentation. Case Presentation: The proband, a 13-year-old female, initially presented with a series of clinical manifestations of fulminant myocarditis. Although recommendation-guided anti-immunotherapy had been provided, this patient still developed into an aggressive cardiomyopathy with biventricular dilation and severe systolic heart failure. Additionally, cardiac magnetic resonance demonstrated circumferential late gadolinium enhancement in left ventricular myocardium with diffuse fibrosis. Whole-exon sequencing identified a de novo missense variant, as c.335T>A (p.L112Q) of the DES gene, resulting in protein dysfunction. And a diagnosis of ACM due to a DES variant had been identified. Finally, this patient received heart transplantation, and biventricular fibrofatty infiltration was confirmed by pathological analysis. Conclusions: This case presented a de novo genetic variant that can induce severe and aggressive heart failure. This finding emphasizes the importance of comprehensive genetic analysis in patients suspected of having fulminant myocarditis, which would greatly benefit the precise clinical management and outcomes.