PC1087: Cardiac Troponin-i Level at 24 Hours After Birth in Stable Newborn Infants

Background: Cardiac troponin-I is a known biomarker of myocardial injury, but its diagnostic utility is unclear in the newborn population. Retrospective studies have shown that elevation of troponin-I levels in newborns with hypoxic-ischemic encephalopathy may be predictive of the degree of hypoxic tissue injury, but the normal ranges have been extrapolated from data in older children or adults. The aim of our study was to establish normative data for cardiac troponin-I in stable newborns, and to assess any variation in levels based on the mode of delivery, newborn resuscitation, and maternal diabetes status.

Methods: This is an IRB-approved, prospective, observational study of babies born >35 weeks’ gestation admitted to our well-baby nursery. Any infants with signs of respiratory distress or congenital heart disease were excluded. After obtaining parental consent, we evaluated troponin-I using a validated point-of-care testing method bundled with state newborn screening at 24 hours of life. Results were kept confidential from the clinical care team unless troponin-I results were at least three-fold the cut-off for the normal level of 0.04 ng/ml in older children or adults (i.e. 0.12 ng/ml), in which pediatric cardiology is consulted to perform an electrocardiogram (EKG) and echocardiography to evaluate cardiac dysfunction. Data collected were mode of delivery, newborn resuscitation, and maternal diabetes status. Descriptive analysis of the troponin-I levels was done to gather normative data for this population. T-test and Wilcoxon signed-rank test were used to compare troponin-I level by parametric and nonparametric data distributions, respectively. A value of p< 0.05 was considered significant.

Results: 128 patients consented, and 110 had adequate samples resulted. Two patients had troponin-I levels (0.12 and 0.32 ng/ml) that warranted EKG and echocardiography—both had normal myocardial function and followed up with their pediatrician with no adverse reports. These patients were considered outliers, and it was discovered that both these infants were born to mothers with SARS-CoV-2 infection during pregnancy. A total of eight patients were born to SARS-CoV-2 positive mothers. These were analyzed as a subgroup, and troponin-I levels were elevated compared to the remaining 102 subjects (p=0.006). There were no differences in troponin-I between the other subgroups, as shown in Table 2.

Conclusion: This study helps establish normative data for cardiac troponin-I levels in healthy term newborns at 24 hours of age. Our current results show no statistically significant differences in troponin-I levels of stable newborns between mode of delivery, delivery resuscitation, or maternal diabetes status. Subgroup analysis of troponin-I levels in neonates born to SARS-CoV-2 positive mothers during pregnancy show elevation when compared to those born to mothers negative for infection. Larger scale studies are warranted to further understand the clinical implications of cardiac troponin-I in neonates born to mothers with SARS-CoV-2 infection during pregnancy.