Cardiac Troponin T in Serum as Marker for Myocardial Injury in Newborns

Abstract

In neonates, acute perinatal asphyxia may lead to ischemic myocardial damage (1). In some cases, subendocardial infarction has been documented (2). Generally, diagnosis of the myocardial injury (MI) is based on clinical findings, suggestive electrocardiographic and echocardiographic patterns (3), decrease in myocardial uptake of thallium (4), and classical creatine kinase (CK)-MB isoenzyme measurement (5). However, CK-MB in serum cannot be regarded as a cardiac-specific marker in the neonate, and extreme caution should be used in the interpretation of increased CK-MB activity during this period (6). Cardiac troponin T (cTnT), the structural protein that binds the troponin complex to the tropomyosin molecular strand, has recently been proposed as a more specific biochemical marker for diagnosis of myocardial infarction in the adult population (7). Here we evaluated the use of cTnT measurement in serum in the diagnosis of MI in newborns, as well as that of the determination of CK-MB mass concentration by a sensitive and specific monoclonal anti-CK-MB antibody-based immunoassay. Three groups of infants were studied. Group I consisted of 27 preterm infants (gestational age ranging from 28 to 36 weeks) without major respiratory and cardiovascular dysfunctions. Group II was 27 healthy full-term newborns (15 born by vaginal delivery and 12 by cesarean section) with a mean gestational age of 39.7 weeks. Group III was composed of seven infants (four preterm and three term) who demonstrated, during the first 3 days after birth, clinical, electrocardiographic, and echocardiographic signs of MI. In particular, in electrocardiogram (ECG) evaluation, MI was considered to be present when inversion of T waves or ST-segment depression ≥1 mm in more than two precordial leads was noted. Groups I and II underwent a clinical examination, ECG, echocardiogram, and blood collection for the measurement of total CK, CK-MB, and cTnT on day 2 after birth. Group III was evaluated …