Utility of rapid B-type natriuretic peptide assay for diagnosis of symptomatic patent ductus arteriosus in preterm infants.

OBJECTIVE: In preterm infants, the rapid and accurate determination of the presence of a hemodynamically significant patent ductus arteriosus (PDA) is extremely important, but this is often difficult. Plasma B-type natriuretic peptide (BNP) measurement has been reported to be a helpful aid in the diagnosis of hemodynamically significant PDA in preterm infants. The aim of our study was to investigate the usefulness of a rapid BNP assay as a diagnostic marker of symptomatic PDA (sPDA) in preterm infants.

METHODS: Sixty-six preterm infants, ranging from 25 to 34 gestational weeks of age, underwent clinical and echocardiographic examinations for PDA every other day from the third day of life until the disappearance of ductal flow. Blood samples were collected and plasma BNP concentrations were measured simultaneously using a commercial kit, (Triage BNP test kit; Biosite Diagnositics, San Diego, CA). When > or =2 clinically significant features of PDA were noted, and a large ductal flow was confirmed by color Doppler echocardiography, sPDA was diagnosed and treated with indomethacin.

RESULTS: On the third day after birth, the mean BNP concentration in the sPDA group (n = 23) was significantly higher than in the control group (n = 43) (2896 +/- 1627 vs 208 +/- 313 pg/mL). Seventeen infants (74%) in the sPDA group became asymptomatic after an initial course of indomethacin and their BNP levels concomitantly decreased. Moreover, BNP concentrations were significantly correlated with the magnitudes of the ductal shunt, such as the ratio of left atrial to aortic root diameter and the diastolic flow velocity of the left pulmonary artery (r = 0.726 and 0.877). The area under the receiver operator characteristic curve for the detection of sPDA was high: 0.997 (95% confidence interval: 0.991-1.004). The best cutoff of BNP concentration for the diagnosis of sPDA was determined to be 1110 pg/mL (sensitivity: 100%; specificity: 95.3%).

CONCLUSION: In preterm infants, the circulating BNP levels correlated well with the clinical and echocardiographic assessments of PDA. Although not a stand-alone test, the rapid BNP assay provides valuable information for the detection of infants with sPDA that require treatment. Moreover, serial BNP measurements may be of value in determining the clinical course of PDA in preterm infants.