Predictive values of N-terminal pro-brain natriuretic peptide after congenital heart disease surgery in children

Objective To explore the potential associations between NT-proBNP level and outcomes in patients with cardiopulmonary bypass (CPB). Methods A total of 415 children undergoing surgery for congenital heart disease were enrolled. Their clinical data were collected and NT-proBNP levels measured during preoperative and early postoperative periods (1, 12, 36, 60 hours and 1 week). Paired t-test and repeated measures analysis of variance (ANOVA) were used for comparing the NT-proBNP levels at different timepoints. Receiver operating characteristic (ROC) curves were adopted to evaluate the diagnostic efficiency of NT-proBNP for predicting the time of mechanical ventilation>48 h, postoperative intensive care unit (ICU) stay>3 days and vasoactive drug use>3 days. General diagnostic efficiency was presented as area under an ROC curve (AUC) and 95% confidence interval (95%CI). Results The levels of NT-proBNP peaked at 12 h postoperation for 296 patients. And the remaining 119 patients peaked later than 12 h. The difference in time of mechanical ventilation postoperation between the groups of NT-proBNP-Peak (within 12 h postoperation)(29.19±33.34) h and NT-proBNP-Peak (after 12 h postoperation)(49.16±85.85 h) was statistically significant (t=2.465, P=0.015). The percentage of vasoactive drug use>3 days was 35.8% (106/296) in group of NT-proBNP-Peak (within 12 h postoperation) and was 52.9% (63/119) in group of later than 12 h postoperation. And the inter-group difference reached statistical significance (χ2=10.318, P=0.002). 12 h NT-proBNP levels of >7 708.71 pg/ml predicted mechanical ventilation beyond 48h showed AUC of 80.1% (95%CI: 75.0%~85.1%) with a sensitivity of 65.1% and a specificity of 81.8%. 12 h NT-proBNP levels of >6 145.67 pg/ml predicted using inotropic therapy beyond 72 h showed AUC of 78.4%(95%CI: 73.9%~82.9%) with a sensitivity of 82.5% and a specificity of 62.7%. In addition, 12 h NT-proBNP levels of >4 981.77 pg/ml predicted ICU stay beyond 72 h showed AUC of 77.5% (95%CI: 73.0%~82.1%) with a sensitivity of 68.7% and a specificity of 76.4%. Conclusions Plasma level of NT-proBNP might be a prognostic indicator during ICU for pediatric surgical patients of congenital heart disease. Key words: Congenital heart disease; Brain natriuretic peptide; Time to peak