Early elevated NT-proBNP but not troponin I is associated with severe bronchiolitis in infants.

Background: We aimed to explore and to compare the association between the NT-proBNP and high-sensitivity troponin I (hs-cTnI) at early stages of acute bronchiolitis with echocardiographic alterations, clinical severity and outcomes.

Methods: A single centre, prospective observational study including previously healthy infants aged 1-12 months with bronchiolitis admitted to a tertiary hospital from April 2019 to March 2020. All patients underwent clinical, laboratory and echocardiographic evaluation at the same time point within 12 h of hospital admission. NT-proBNP > 1121 pg/ml and hs-cTnI > 26 ng/L were considered elevated. The primary outcome measure was the association of raised cardiac biomarkers with the need for PICU admission.

Results: We enrolled 40 infants with median levels of NT-proBNP of 1176 (520-3030) pg/ml and hs-cTnI of 11.5 (5-21) ng/L at the time of hospital admission. Raised levels of NT-proBNP and hs-cTnI in 50% and 20% of cases, respectively. Of them, 15 (37%) required PICU admission during the hospitalization. Increased NT-proBNP was associated with PICU admission (adjusted OR 9.5 (CI95% 1.4-64); p = 0.020), prolonged hospitalization (β = 2.7; p = 0.012) and duration of oxygen administration (β = 2.7; p = 0.004) in the multivariate analysis. There were no differences in hs-cTnI levels regarding PICU admission (p = 0.866). Increased hs-cTnI levels were only associated with oxygen administration duration (Spearman rho = 0.38; p = 0.017), but this association disappeared in the multivariate analysis. Only NT-proBNP was associated with echocardiographic parameters of myocardial dysfunction (p < 0.001), and pulmonary hypertension (p < 0.001) CONCLUSION: Early elevated NT-proBNP but not hs-cTnI could be used as a biomarker for myocardial strain and disease severity in bronchiolitis.