Myocardial injury in infants ventilated on the paediatric intensive care unit: a case control study

INTRODUCTION Cardiac troponin T (cTnT) has been used to assess prevalence of myocardial injury in critically ill children. The majority of studies investigated patients undergoing cardiac surgery. Myocardial injury has been associated with increased mortality. Our objectives were to investigate whether cTnT levels are elevated in infants without congenital heart disease admitted to the paediatric intensive care unit (PICU) and whether levels are associated with increased disease severity. METHODS We measured cTnT in consecutive infants (<12 months old) without congenital heart disease admitted to the PICU and healthy infants. The Paediatric Index of Mortality (PIM) score was determined in patients on the PICU. RESULTS We recruited 107 infants: 47 infants admitted to the PICU and 60 healthy controls. Controls were, with a median (interquartile range (IQR)) age of 20 (12 to 34) weeks, significantly older than cases, with a median age of 6.5 (0.3 to 20.6) weeks. CTnT levels were, with a median (IQR) of 18 (10 to 60) pg/ml, significantly higher in admissions to the PICU than in controls, with a median level of 10 (10 to 10) pg/ml (95th centile of 20 pg/ml) (p < 0.001). There was a significant positive correlation (r = 0.41, p = 0.004) between PIM score and cTnT levels. Admissions under one month old had higher cTnT levels than older patients (p = 0.013) but the PIM score was not significantly different between them. When corrected for age and weight the correlation of PIM and cTnT was no longer significant. CONCLUSION Infants on the PICU in the neonatal period have higher cTnT levels compared to older infants despite not having more severe disease.