<p><strong>BACKGROUND: </strong>Premature infants with severe bronchopulmonary dysplasia (sBPD) are at risk of pulmonary hypertension (PH). Serum brain natriuretic peptide (BNP) is used to predict disease severity in adult PH. Its diagnostic utility in sBPD-associated PH is unknown.</p>

<p><strong>OBJECTIVE: </strong>The aim of this paper was to determine the accuracy of BNP, against echocardiogram (echo), to diagnose PH in infants born &lt;32 weeks' gestation with sBPD.</p>

<p><strong>METHODS: </strong>We conducted a retrospective cohort study of all infants with sBPD with an echo and BNP within a 24-h period, at ≥36 weeks postmenstrual age. PH was defined as: right ventricular pressure &gt;½ systemic blood pressure estimated from tricuspid regurgitant jet or patent ductus arteriosus (PDA) velocity, bidirectional or right-to left-PDA, and/or flat/bowing ventricular septum at end-systole. Receiver-operating characteristic (ROC) curves were constructed to test the diagnostic accuracy of BNP.</p>

<p><strong>RESULTS: </strong>Of 128 infants, 68 (53%) had echo evidence of PH. BNP was higher among the infants with PH (median [interquartile range]: 127 pg/mL [39-290] vs. 35 [20-76], p &lt; 0.001). The area under the ROC curve for diagnosing PH using BNP was 0.74 (95% CI 0.66-0.83). At an optimal cutpoint of 130 pg/mL, BNP correctly classified the presence or absence of PH in 70% of the infants (specificity: 92, sensitivity: 50%).</p>

<p><strong>CONCLUSIONS: </strong>BNP, relative to concurrent echo, demonstrated moderate accuracy for diagnosing PH in this cohort of preterm infants with sBPD. BNP may help rule in PH in this population but has low utility to rule out the disease.</p>

<p><strong>BACKGROUND: </strong>Pulmonary artery acceleration time measured by echocardiography inversely correlates with pulmonary artery pressures in adults and children older than 1&nbsp;year of age. There is a paucity of data investigating this relationship in young children, particularly among preterm infants.</p>

<p><strong>OBJECTIVE: </strong>To characterize the relationship between pulmonary artery acceleration time (PAAT) and pulmonary artery pressures in infants.</p>

<p><strong>DESIGN/METHODS: </strong>Patients ≤&nbsp;1&nbsp;year of age at Children's Hospital of Philadelphia between 2011 and 2017 were reviewed. Infants with congenital heart disease were excluded, except those with a patent ductus arteriosus&nbsp;(PDA), atrial septal defect&nbsp;(ASD), or ventricular septal defect&nbsp;(VSD). Linear regression analysis was used to assess the correlation between PAAT measured by echocardiography and systolic pulmonary artery pressure, mean pulmonary artery pressure, and indexed pulmonary vascular resistance from cardiac catheterization.</p>

<p><strong>RESULTS: </strong>Fifty-seven infants were included, of which 61% were preterm and 49% had a diagnosis of bronchopulmonary dysplasia. The median postmenstrual age and weight at catheterization were 51.1&nbsp;weeks (IQR 35.8-67.9&nbsp;weeks) and 4400&nbsp;g (IQR 3100-6500&nbsp;g), respectively. Forty-four infants (77%) had a patent ductus arteriosus (PDA). There was a weak inverse correlation between PAAT with mPAP (r&nbsp;=&nbsp;-0.35, P&nbsp;=&nbsp;0.01), sPAP (r&nbsp;=&nbsp;-0.29, P&nbsp;=&nbsp;0.03), and PVRi (r&nbsp;=&nbsp;-0.29, P&nbsp;=&nbsp;0.03).</p>

<p><strong>CONCLUSION: </strong>There is a weak inverse relationship between PAAT and pulmonary artery pressures. This relationship is less robust in our population of infants with a high incidence of PDAs compared to previous studies in older children. Thus, PAAT may be less clinically meaningful for diagnosing pulmonary arterial hypertension in infants, particularly those with PDAs.</p>