Background: Troponin-I (Tn-I) is a well-recognized early postoperative marker for myocardial damage in adults and children. The present prospective study was undertaken to investigate whether a postoperative Tn-I value higher than 35 microg/l is able to predict long-term outcome as it does in early postoperative course, after surgery for congenital heart defects (CHD).
Materials and methods: Five hundred and twenty patients (median age 11 months; male 54.7%: 284 patients) undergoing congenital heart defect repair on cardiopulmonary by-pass were prospectively updated in our database including postoperative Tn-I values. Seventy of them (13.4%) (mean age 2.6+/-5.8 months) (70/520) experienced low output syndrome in the early postoperative period. According to the complexity of their malformations, we have arbitrarily divided these patients into two groups: group A included atrial and ventricular septal defects (13 patients), while group B included hypoplastic left heart syndrome, atrio-ventricular canal, transposition of great vessels, tetralogy of Fallot, double outlet right ventricle, truncus arteriosus, total anomalous venous return, and other combined diseases (57 patients). These patients are the object of our study. We reviewed clinical, laboratory, and echocardiographic data performed in the immediate postoperative course (within 24 h) and in the follow-up.
Results: In this study, 13 patients died (13/70 patients; 18.5%), 12 in group B and 1 in group A. In deceased patients, mean Tn-I value was 130+/-175 microg/l (CK-MB 570+/-280 microg/l). Conversely, survivors showed a lower mean Tn-I value (25.5+/-28.9 microg/l; CK-MB 76+/-86 microg/l). Overall, Tn-I peak value was higher than 35 microg/l in 19 patients (19/70; 27.2%); among these, 9 died (median Tn-I was 163+/-186 microg/l), whereas in survivors it was 73.4+/-37 microg/l (p=0.37). The remaining four patients who died had a median Tn-I value of 21 microg/l. When Tn-I exceeded 35 microg/l (>100 microg/l in two cases), at echocardiogram a severely depressed cardiac function was evident. Nevertheless, at long-term follow-up (12+/-6 months), the echocardiogram showed an enhanced cardiac performance with an ejection fraction of 70+/-8.5% in all; none of these patients presented with worsened ventricular function.
Conclusion: Cardiac Tn-I is a specific and sensitive marker of myocardial injury after cardiac surgery and it may predict early in-hospital outcomes. However, by long-term echocardiographic analysis, cardiac Tn-I value looses its prognostic significance and therefore it is not a predictor of long-term ventricular dysfunction.