Desmoplakin Cardiomyopathy Mimicking Chronic Myocarditis in a Patient With Malignant Ventricular Tachycardia: The Value of Multimodality Diagnosis and Integrated Management

Background Desmoplakin (DSP) cardiomyopathy is an inherited arrhythmogenic cardiomyopathy characterized by myocardial fibrosis, inflammatory-like myocardial injury, and a left ventricular-predominant phenotype. Ventricular arrhythmias may occur despite only mildly reduced left ventricular systolic function, and the disease can mimic chronic myocarditis. Case presentation A 37-year-old woman presented with recurrent sustained monomorphic ventricular tachycardia and a family history of sudden death. Echocardiography and cardiac magnetic resonance showed mildly reduced left ventricular systolic function (43–44%) and a nonischemic late gadolinium enhancement pattern predominantly involving the subepicardial and mid-myocardial layers of the basal anterior and lateral left ventricular walls. Epicardial mapping demonstrated an extensive posterolateral left ventricular substrate with low-voltage scar, late potentials, and delayed conduction. Epicardial radiofrequency substrate modification was performed, followed by endomyocardial biopsy and extravascular implantable cardioverter-defibrillator implantation. Histopathology initially favored chronic myocarditis. Genetic testing subsequently identified a pathogenic heterozygous truncating variant in DSP (c.4198C > T, p.Arg1400Ter), supporting the diagnosis of DSP cardiomyopathy. At 1-month follow-up, no ventricular tachycardia or device therapy was recorded, and LVEF improved to 50%. Conclusions DSP cardiomyopathy should be considered in patients with malignant ventricular arrhythmias disproportionate to the degree of left ventricular dysfunction, particularly when cardiac magnetic resonance shows a nonischemic left ventricular fibrosis pattern and there is a family history of sudden death. Integrating electrophysiological, imaging, pathological, and genetic findings may help distinguish DSP cardiomyopathy from chronic myocarditis and guide arrhythmic management.