Background: B-lines detected by lung ultrasound are established markers of pulmonary congestion in adults with heart failure. However, their role in pediatric congenital heart disease (CHD) remains unclear. This study aimed to evaluate whether a semiquantitative lung ultrasound (LUS) score correlates with heart failure severity in infants with left-to-right shunts.

Methods: This cross-sectional observational study included 50 infants with post-tricuspid left-to-right shunts. Clinical assessment was performed using the modified Ross score, NT-proBNP measurement, and lung ultrasound. A 14-zone LUS protocol was applied, scoring each zone based on B-line count (0–3). Total and modified LUS scores were calculated. Correlation with Ross score and NT-proBNP was analyzed, and ROC curve determined the optimal LUS cut-off for detecting moderate/severe heart failure.

Results: Median age was 4 months; 82% had ventricular septal defect. No significant correlation was found between LUS scores and modified Ross score (r = 0.26, p = 0.06) or NT-proBNP (r = −0.06, p = 0.63). ROC analysis yielded an AUC of 0.64; LUS cut-off of 11 predicted moderate/severe heart failure with 75% sensitivity and 55% specificity. B-lines were predominantly observed in posterior lung zones.

Conclusion: LUS shows limited accuracy in assessing heart failure severity in infants with left-to-right shunts. Further research and standardized scoring protocols are needed before LUS can be integrated into pediatric heart failure evaluation.

Anmol Rathore completed her postgraduation in pediatrics in India and is currently working as a senior clinical fellow in Oxford university hospital at the neonatology department in the UK. She worked on the topic of Lung USG as her thesis while pursuing her postgraduation in India and has a keen interest in cardiology as well as point of care ultrasound and its potential in pediatrics.