P2.I180: Utility of urinary NT-proBNP in congenital diaphragmatic hernia (CDH)-A prospective pilot study

Background: Pulmonary hypertension (PH) and cardiac dysfunction (CD) seen in Congenital Diaphragmatic Hernia (CDH) are best-assessed using echocardiography (echo). An inexpensive, rapid turnaround biomarker of cardiac dysfunction or PH severity would be a valuable adjunct to echo to evaluate PH and CDH. N-terminal brain Natriuretic Peptide (NT-Pro BNP), which is secreted from the cardiac ventricles in response to wall stress, is one such promising biomarker. Plasma NT-proBNP has been studied in the CDH population. We sought to investigate the utility of urinary NT-proBNP to prognosticate development of PH and cardiac dysfunction in CDH.

Methods: Prospective observational study of neonates with CDH enrolled from May 2022-January 2024. Urine samples to detect NT-proBNP levels and corresponding plasma NT-proBNP levels were collected at 24 Hours of life (HOL), at the time of the first echo and with the post-repair echo. Urinary NT-proBNP and its ratio to urinary creatinine (UNBCR) were analyzed. Spearman’s correlation was used to quantify the association between urinary and plasma NT-ProBNP values. Logistic regression and receiver operating characteristic (ROC) curve analyses were used to investigate the association with the need for ECMO and need for PH therapy. The Kruskal-Wallis test was used to test the association of echo parameters with urinary NT-ProBNP and UNBCR values.

Results: 30 patients were included in the analysis, of which four (13.3%) required ECMO. Both urinary NT-proBNP (pg/dL) (r=0.416, p=0.022) and UNBCR (r=0.609, p< 0.001) exhibited a significant positive association with Plasma NT-proBNP (pg/ml) (Figure 1). Every 1-unit increase in UNBCR level increased the odds of needing ECMO by 13.5%. UNBCR >26.5 ng/mg provided a sensitivity of 75% and specificity of 96.2% in predicting need of ECMO (p=0.011, area under ROC curve=87.5%). Patients requiring PH therapy had marginally higher urinary NT-proBNP levels (p=0.077) compared to those not requiring PH therapy (median 59900 vs 13050 pg/dl, respectively). Urinary NT proBNP and UNBCR values’ associations with pre and post repair echocardiographic parameters are shown in Table 1.

Conclusion: Urinary NT-proBNP correlated well with plasma NT-proBNP and echocardiographic markers for PH and CD in the CDH population. The findings of our pilot study are promising, but need to be validated by larger studies.