Sudden Death Due to Concurrent Arrhythmogenic Cardiomyopathy and Myocarditis: An Autopsy Case

Arrhythmogenic cardiomyopathy (ACM) is a rare genetically determined myocardial disease characterized by fibrofatty substitution of the myocardium which predisposes the patient to sudden cardiac death (SCD). In addition to the classic pathology seen in ACM, inflammatory infiltrates have been occasionally reported, suggesting a close pathophysiological relationship between ACM and inflammation. Evidence indicates that this inflammation is related to electrical instability resulting in ventricular tachycardia and SCD. This is an autopsy case of a 52-year-old female who died suddenly of concomitant ACM and myocarditis, fulfilling both histological and immunohistochemical diagnostic criteria. With the features of fatty variant ACM, the inflammatory infiltrate was prominent in the subendocardial layer of the left ventricle and was composed of mostly CD3-positive lymphocytes as well as some neutrophils and macrophages. In forensic practice, this case highlights the necessity of collecting multiple representative portions of cardiac tissue to search for inflammation, which can easily explain the cause of death and the dying process in ACM.