Cardiac Troponin T in Serum As Marker for Myocardial Injury in Newborns (Technical Briefs‪)‬

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 [greater than or equal to]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 with ECG and echocardiography at presentation and every 24 h until clinical recovery or death. Total CK, CK-MB, and cTnT were measured 12 and 48 h after presentation and, when possible, after 45 days. The protocol of the study was approved by the local Ethical Committee, and parental consent was obtained.