Aminoterminal B-type natriuretic peptide (NT-proBNP) in the therapy of patent ductus arteriosus.

Background: NT-proBNP is a reliable index in case of cardiac diseases.

Objective: To evaluate the diagnostic usefulness of NT-proBNP as index of the closure of patent ductus arteriosus (PDA) in ELBW.

Methods: Considered 73 ELBW (mGA 26+3 weeks; mBW 789 g) with echocardiographical diagnosis of PDA. The closure of the duct was spontaneous in 22%, pharmacological in 49.3% and by surgical ligation in 28.7%. Plasma NT-proBNP levels were measured on day 3 in 35 preterm infants; in 20 of them concentrations of the peptide were assayed on day 3 and on closure of the duct.

Results: On day 3 the median of NT-proBNP levels was 13718 pg/ml (range 1918-70000). Peptide concentrations did not differ between pharmacological treatment and surgical ligation (respectively 13718 and 12342 pg/ml; p = 0.33). Concentrations of NT-proBNP were significantly lower on the closure of the duct (p < 0.0001) compared to concentrations on day 3 (median 12666 at day 3 versus 2443.5 pg/ml at closure), with a decrease of 80.71%.

Conclusions: ELBW showed high variability of NT-proBNP concentrations both on day 3 and on closure of PDA. Although NT-proBNP high levels were indicative of the presence of hsPDA, due to the extreme heterogeneity of the values it was not possible to determine an absolute cut-off concentration of NT-proBNP below which closure of the duct occurred, while a decrease of NT-proBNP > or =80% was a reliable index of PDA closure.