Investigating pathological features of myocarditis-related sudden cardiac deaths in Egypt

Abstract Background Myocarditis is an inflammatory condition of the myocardium. A definitive diagnosis requires histopathological examination. The scarcity of autopsy data has led to this study, which analyzed the histopathological features of myocarditis-related deaths referred to the Egyptian Forensic Medicine Authority. Results Out of 652 cases of sudden cardiac death (SCD), 42 cases (6.4%) were related to myocarditis. Males accounted for 66.7% of myocarditis cases, and 47.6% of deaths were in the third decade. There was a positive medical history in 66.7% of investigated cases, including rheumatic heart disease (RHD) (50%), renal infections (32.1%), septicemia (14.3%), and allergies (3.6%). Fever was reported in 71.4% of cases, while the others died without developing fever. On gross examination, 85.7% of hearts appeared normal, while the remaining showed areas suspicious of myocarditis. Neutrophilic myocarditis was the most common subtype (71.4%), followed by lymphocytic myocarditis (23.8%). Eosinophilic and giant cell myocarditis were identified once. A focal infiltration pattern was observed in 78.6% of cases. Approximately, 80% of deaths in the first decade were attributed to lymphocytic myocarditis, whereas 95% of deaths in the third and 75% of fourth decade had neutrophilic myocarditis. All cases of lymphocytic myocarditis lacked a history of infections and fever. On autopsy, these cases had normal myocardium during gross examination. In contrast, 90% of cases of neutrophilic myocarditis had a positive medical history. Also, all cases with neutrophilic myocarditis had a history of fever, and autopsies revealed significant evidence of infections. There were significant differences between cases of neutrophilic and lymphocytic myocarditis in terms of age, medical history, presence of fever, and associated autopsy findings ( p values < 0.05). Conclusions This study provided the first forensic pathological analysis of myocarditis in the Arab world, highlighting the need to guard against infections in developing societies and emphasizing the importance of histopathological examinations for SCDs. The study’s limitations included the probability of selection bias, which is an inherent limitation in autopsy-based studies. Also, the lack of microbiological and immunological analyses stemming from the retrospective nature of the study was another limitation that should be addressed in future prospective studies.