2 syndromes conﬁrmed by laboratorial and clinic tests were excluded from the study. Blood samples (0.3 mL) were collected with 24 and 48 hours of life in heparinized syringes, taken to the laboratory to be stored for further analysis. The biochemical analysis was conducted via the Immunoassay Elecsys Troponin T STAT (Roche). We arbitrarily deﬁned a positive test if cTnT blood levels were >0.1 ng/dL. Echocardiograms were performed in the ﬁrst 72 hours of life by a cardiologist consultant. The parameters recorded by the echocardiogram were mild, moderate, or severe dysfunction, cardiac dilatation, and persistence of ductus arteriosus. Clinical data of prenatal care, multiparity, hypertension, diabetes, steroid use, fetal distress, prolonged rupture of membranes (more than 24 hours), perinatal infection, and type of delivery were recorded. Neonatal variables included Apgar scores, birth weight, gestational age, CRIB, and SNAPPE-II, as well as need for resuscitation in the delivery room. We followed infants up to discharge and registered most important neonatal morbidities: RDS, pneumonia, use of surfactant, need of oxygen, length of mechanical ventilation, duration of nasal CPAP, hypotension and persistence of ductus arteriosus, use of indomethacin, use of inotropic drugs (dopamine, dobutamine) and diuretics, the presence of infection at admission, and antibiotic use. For statistical analysis we used the t-test, Non-parametric tests, chi-square and logistic regression. The study was approved by the Ethics Committee Review Board of the Institution. 3. Results Between January 1st, 2004, and July 31st, 2005, 156 pre- term infants with less than 1500 g were admitted to the high- risk nursery of Laranjeiras Perinatal Clinic. We excluded 37 infants due to death before 24 hours of life and congenital malformations. Additional 3 infants were excluded because we were unable to obtain troponin values. Therefore, the prospective study was conducted in 116 patients within this period. The main maternal morbidities were arterial hyperten- sion (41.2%), multiple gestations (24.4%), and the pro- longed rupture of membranes (17.6%). Infection related to premature birth was found in 12.7% of the patients. The use of pre-natal steroids was a common practice (76.3%), and maternal Dopple rﬂuxometry was abnormal in 56 patients (47.5%). Mean Apgar scores at 1 and 5 minutes were 6.2 ± 2.1 and 8.3 ± 1.1, respectively. A total of 95 newborns (80.5%) required resuscitation in the delivery room. The ventilation with positive pressure (VPP) was the most used procedure, followed by orotracheal intubation (36.4%). Seventy-eight preterm infants (65.5%) presented RDS, and surfactant was used in 58% of cases. Nasal constant positive airway pressure (CPAP) was used in 73.5% of VLBW infants, for 11.3 ± 10.6 days and median of 8 days. A total of 95 infants required oxygen therapy with a median of 12 days of therapy. International Journal of Pediatrics Table 1: Main Characteristics of the Studied Population (n = 116). Birth weight (g) Gestational age (weeks) CRIB SNAPPE Mechanical ventilation Persistence of Ductus Arteriosus Use of Dopamine Use of Dobutamine Early sepsis Deaths VPP = Ventilation with positive pressure. 1050 ± 306 29.2 ± 2.3 4.1 ± 3.9 22.2 ± 2.4 61.9% 55.5% 34.5% 37% 23.5% 6.7% Sixty infants (55.5%) had a diagnosis of PDA; among those, 45.4% were treated with indomethacin and 10.1% had the ductus surgically ligated. A total of 86 patients had an echocardiogram done in the ﬁrst week of life. Severe dysfunction was found in 5.9%, moderate dysfunction in 5%, and mild dysfunction in 13.5%; and 35.3% presented cardiac overload. Pulmonary hypertension was diagnosed in 9.2% of patients. The mean hospital stay was 62.7 ± 36.1 days with median of 58 days. Table 1 shows characteristics of the studied population. One hundred and sixteen samples were obtained within 24 hours (70 samples with values ≤0.10 or undetectable). At 48 hours, we obtained 102 samples (57 samples with values ≤0.10 or undetectable). For the positive samples (values >0.10), the median cTnT at 24-hour was 0.193 (0.1– 0.79 ng/mL) and at 48 hours it was 0.293 (0.1–1.0 ng/mL). We used the 24-hour results of cTnT in the comparisons below. Several factors were associated to the increase of cTnT in the univariate analysis. Tables 2 and 3 illustrate the main categorical and continuous variables studied. 3.1. Multivariate Analysis: Logistic Regression. We conducted a logistic regression analysis and included in the model all variables included in the univariate analysis and considered the cardiac troponin T as dependent variable. Among the regression models tested, we chose the one that seemed more adequate, both from the statistical and biological standpoint. A patent ductus arteriousus and dopamine use increased the chance of a newborn presenting positive cTnT in 3.6 (0.95–13.3) and 5.68 (1.5–20.8) times, respectively. On the other hand, the presence of abnormal Doppler and diuretic use reduced the chance of a newborn presenting positive cTnT in 0.27 (0.09–0.7) and 0.12 (0.02–0.5), respectively. The increase in the gestational age of the newborn has a protective eﬀect with an odds ratio of 0.65 (0.5–0.8). 4. Discussion Cardiac troponin T and I (cTnT, cTnI) are accepted as the gold standard assay for diagnosis of myocardial infarction in adults. In the last decade a large number of publications