Objectives. The aim of this study was to investigate the occurrence of myocardial injury in critically ill children through assessment of cardiac troponin T levels and whether levels are associated with disease severity and myocardial dysfunction measured by echocardiography. Methods. Over a 6-month period, this case control study included 50 patients admitted to Pediatric Intensive Care Unit of Zagazig University Children’s Hospital. Twenty-five healthy children were included as a control group. Demographic and clinical data including the pediatric index of mortality II score were recorded. Echocardiographic examination was done and level of cardiac troponin T was measured using Elecsys Troponin T STAT Immunoassay. Results. Cardiac troponin T levels were significantly higher in critically ill in comparison to healthy children (median 22 (18–28)？pg/mL versus 10 (10-10)？pg/mL, ). Cardiac troponin T levels correlated positively with duration of ventilation as well as with disease severity and correlated negatively with left ventricular fractional shortening. Moreover, cardiac troponin T levels were significantly higher in nonsurvivors when compared to survivors (median 34.5 (27.5–41.5)？pg/mL versus 20 (18–24) pg/mL, ). Conclusion. In critically ill children, cardiac troponin T levels were elevated and were associated with duration of ventilation and disease severity. 1. Introduction Cardiac troponins I and T are regulatory proteins that control the calcium-mediated interaction of actin and myosin, producing myocardial contraction [1]. Since troponins do not occur in extracellular space, their appearance in serum is sensitive and specific marker of myocardium damage [2]. Cardiac specific troponins T and I have been established as the gold standard biochemical markers for myocardial necrosis [3]. An unexpectedly high incidence of clinically unrecognized myocardial injury, assessed by elevated cardiac troponin I levels, has previously been reported in critically ill adult patients [4]. Elevated cardiac troponins levels have been detected in children critically ill with congenital heart disease before and after cardiac surgery [5]. In patients without congenital heart disease raised cardiac troponin levels have been found in pediatric intensive care unit (PICU) admissions with severe respiratory syncytial virus infection [6] and with meningococcal and other forms of septicemia [7, 8]. To our knowledge, there is no published data concerning myocardial injury in PICUs in our country. So, the aim of this study was to evaluate myocardial injury in critically ill
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