Abstract

Background: B-type natriuretic peptide (BNP) is a marker for ventricular dysfunction secreted as a pre-prohormone, pro-B-type natriuretic peptide (proBNP), and cleaved into BNP and a biologically inactive fragment, N-terminal pro-B-type natriuretic peptide (NT-proBNP). Little is known about the clinical usefulness of NT-proBNP in preterm infants.

Objective: To evaluate the usefulness of plasma NT-proBNP in diagnosing haemodynamically significant patent ductus arteriosus (hsPDA) in neonates and examine some factors that might affect this.

Methods: Infants born at <34 weeks’ gestational age (GA) and <2 kg birth weight (BW) were prospectively enrolled within 6–12 hours of birth. Plasma NT-proBNP levels were measured on days 1, 3, 5 and 10 with simultaneous echocardiography done to detect hsPDA and assess ventricular function. Significant PDA was diagnosed by large ductal flow with left to right shunt on colour Doppler, measuring >1.6 mm on two-dimensional echocardiography, along with clinical features of PDA.

Results: Forty-nine infants were analysed. Median GA was 30 weeks (range 24–33) and median BW 1220 g (range 550–1950). Eighteen infants with hsPDA had higher day 3 plasma NT-proBNP values (median 32 907 pg/ml; range 11 396–127 155) (p<0.001) than controls (median 3147 pg/ml; range 521–10 343). Infants who developed sepsis had higher day 10 plasma NT-proBNP levels. Area under receiver operator characteristic curve for detection of hsPDA, by day 3 NT-proBNP value, was significant 0.978 (95% CI 0.930 to 1.026). NT-proBNP was predictive of hsPDA (sensitivity 100%; specificity 95%) at a cut-off value of 11 395 pg/ml.

Conclusion: Plasma NT-proBNP level on day 3 is a good marker for hsPDA in preterm infants. Serial measurements of NT-proBNP may be useful in assessing the clinical course of PDA.