Morphological and immunohistochemical characteristics of the heart of patients with COVID-19

OBJECTIVE: To analyze the pathomorphological and immunohistochemical characteristics of the hearts of patients who died from COVID-19. MATERIAL AND METHODS: A comprehensive pathomorphologic study of the heart in 88 autopsies of patients who died from severe COVID-19 was performed. The presence of SARS-CoV-2 infection was confirmed by positive PCR tests in all cases. Immunohistochemical study was used to analyze the expression of viral nucleocapsid protein (NP), CD3, CD68, CD31, CD34, Willebrand factor (vWF) in cell populations and myocardial structures. RESULTS: In most cases, polymorphism of structural changes was observed, which was expressed in a combination of signs of chronic and acute myocardial damage. Numerous foci of interstitial and perivascular fibrosis and lipomatosis, irregular hypertrophy of cardiomyocytes, amyloid deposits were indicative of previous cardiovascular diseases. Acute and subacute pathological changes in myocardium included circulatory disorders (hyperemia, intraluminal megakaryocytes, microvascular thrombosis, interstitial edema), vascular damage, and alterative changes in cardiomyocytes. Lymphomacrophage infiltration was present in 45% of cases and was associated with immunohistochemical detection of NP in cardiomyocytes and vascular cells. Weak expression of CD31 and high expression of vWF in microvascular endothelium was found. CONCLUSION: NP expression in cardiomyocytes, macrophages and endothelial cells of cardiac vessels indicates their direct infection with SARS-CoV-2 virus and possible long-term persistence of viral infection. It was found that in severe COVID-19 CD3- and CD68-positive cells are detected in the heart; endothelial dysfunction is observed, which is indicated by decreased expression of CD31 and high expression of vWF. The identified myocardial changes may influence the development of post-COVID cardiovascular complications.