Perioperative urinary NT-ProBNP values and their usefulness as diagnostic and prognostic markers in children with congenital heart disease

Introduction: NT-proBNP and especially the changes in values are important markers in patients with congenital heart disease (CHD). NT-proBNP values determined from a urine sample correlate well with the plasma values of NT-proBNP. This study investigated the perioperative development of plasma and urinary values, examining their diagnostic and prognostic value.

Methods: 83 children undergoing cardiac surgery for a myriad of CHDs were included. Urine and plasma samples were collected at different points in time. Urinary values were corrected for urine creatinine concentration and transformed into Lg10-values.

Results: The correlation between urine and plasma is weaker postoperatively (r = 0.70-0.80) in comparison to preoperatively (r = 0.87). Neonates had higher urinary values than older children. A ROC-analysis for the differentiation between complex and simple CHD showed an area under the curve of 0.854 for zlog-NT-proBNP plasma values and 0.826 for creatinine corrected urine values. A decline of NT-proBNP plasma values from the day before surgery to the time after intubation correlated with the duration of postoperative non-invasive ventilation (r = 0.9, sig. < 0.001).

Conclusion: Urinary NT-proBNP shows potential in discriminating between complex and simple CHD. This study is the first to show a prognostic role of NT-proBNP in establishing spontaneous respiration postoperatively in children with CHD.