Myocarditis is an inflammatory heart disease triggered by the action of infectious agents or toxins, which lead to myocyte damage by direct action or by exacerbated activation of the immune system. It can culminate in cardiac dilation, drop in ejection fraction, arrhythmias, or even sudden death. We call “acute myocarditis,” the clinical condition that begins less than 30 days ago. According to recent records, acute myocarditis is more prevalent in young adults, mainly women, and its cause is predominantly infectious, with enterovirus, coxsackie virus, parvovirus B19, and, more recently, the COVID-19 virus as examples of viral etiological agentes.^, Enteropathogenic bacteria such as Salmonella, Shigella, and Campylobacter are also some of the main causes of myocarditis identified in case series. Zonulin is a protein that modulates intestinal permeability. Its expression leads to the weakening of occlusion junctions present in intestinal epithelial cells. This expression is stimulated by certain enteropathogens, facilitating the translocation of agents and toxins into the body,^, leading to a state of endotoxemia. Presepsin is considered a reliable marker of low-grade endotoxemia and an indirect marker of increased intestinal permeability.^,

In this observational cross-sectional study, researchers evaluated the possible relationship between intestinal permeability and acute myocarditis by analyzing serum levels of zonulin and presepsin in patients with acute myocarditis compared to individuals without the disease. Acute myocarditis was defined based on clinical history and laboratory elevation of biomarkers such as CK-MB and troponin-I. A total of 138 consecutive individuals were observed, 68 with acute myocarditis and 70 in the control group, with no difference in basic demographic characteristics between groups. C-reactive protein (CRP) levels, fibrinogen, peak CK-MB and peak troponin-I were significantly higher in the myocarditis group than in the control group. It is also interesting to mention that the group of patients with myocarditis had a significantly higher history of COVID-19 or vaccination against COVID-19 in the last six months compared to the control group. The researchers found that zonulin and presepsin levels were statistically higher in the group of patients with myocarditis (p<0.001). Even patients with higher levels of zonulin had lower left ventricular ejection fraction, higher arrhythmia rates, and greater gastrointestinal complaints. It was also observed that zonulin levels are positively related to presepsin (r=0.461), CK-MB peak (r=0.744), and troponin peak (r=0.627); such results show that zonulin and presepsin levels are positively associated with the severity of cardiac injury, as measured by CK MB and troponin markers. In multivariate binary logistic regression analysis, presepsin and zonulin were identified as independent predictors of the disease. Analysis of the ROC curve was performed, showing that the predictive values for acute myocarditis of zonulin and presepsin were statistically significant (p < 0.001, for both).

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