A new approach to the interpretation of B-type natriuretic peptide concentration in children with congenital heart disease

Abstract Objectives BNP is the unique cardiac marker that reflects not as much as the degree of heart muscle damage, but mostly the severity of hemodynamic disorder, which is important in congenital heart disease. The only disadvantage of this marker is the barely studied reference values for children. It is known that the younger the child is, the higher the BNP value will be. By shifting from interpreting the absolute values towards the application of zlog-transformed data in clinical practice, we can overcome the above problems. Methods We performed an age-adjusted zlog transformation of BNP concentration. The age dependence was accounted for by a piecewise linear interpolation of the logarithms of BNP concentration among healthy children in different age groups from the logarithms of age. Results The concentration of BNP was measured in 351 patients (under 1 year old) with various heart diseases. The median age at the time of testing was 52 days [10; 166]; the median weight was 4.1 kg [3.2; 6.2]. The conditions we investigated included almost all known congenital heart diseases, as well as primary cardiac tumors. After the zlog transformation, we eliminated age-dependence, which was proved by comparing BNP concentrations in two groups of patients with univentricular and biventricular hemodynamics. Conclusions BNP in patients with congenital heart disease reflects the severity of hemodynamic disorders, and zlogBNP is an objective, age-independent and clear mechanism that can be used to interpret this cardiac marker.