Pulmonary embolism causes endomyocarditis in the human heart

Background: Pulmonary embolism (PE) is a significant cause of morbidity and mortality. In a recent study in patients with PE, an increased level of macrophages was found in the right ventricle. Objective: To evaluate the presence of inflammatory cells, myocytolysis and intracavitary thrombi in the left and right ventricle of patients who died because of PE as a putative new source of heart failure. Patients and methods: 22 patients with PE were studied. For comparison, eight controls and 11 patients who died of chronic pulmonary hypertension (PHT) were used. Slides of the left and right ventricle were stained with antibodies, identifying neutrophilic granulocytes, lymphocytes and macrophages, which were subsequently quantified. Myocytolysis was visualised using complement staining. Thrombi were identified by conventional staining. Results: Compared with controls, in patients with PE a significant increase in extravascular localisation of all three inflammatory cells was found both in the right and left ventricle, coinciding with myocytolysis, indicative for myocarditis. No increase in inflammatory cells was found in patients with PHT. Endocardial cellular infiltration was also found, partly coinciding with the presence of ventricular thrombi. Conclusions: In patients with PE, endomyocarditis and intracavitary thrombi in the left and right ventricle were found. These abnormalities may be an additional new explanation for the observed cardiac enzyme release and functional abnormalities of the heart in these patients and may contribute to the morbidity and mortality of the disease.