Based on the combined detection of cTnI and CK-MB concentrations in 292 critically ill children without primary cardiac disease, this study aimed to determine the incidence of myocardial injury in critically ill children without primary cardiac disease; explore the associations between myocardial injury and disease progression and prognosis; and emphasize the need for early detection of myocardial injury, timely treatment, and improvement of prognosis. This evidence concerns the gene TNNI3 and heart disorder.