The most frequent abnormality of the valves involved in rheumatic heart disease is mitral regurgitation. A promising supportive diagnostic tool for rheumatic heart disease is the N-terminal pro-brain natriuretic peptide, which can identify mitral valve damage.

To prove a positive correlation between N-terminal pro-brain natriuretic peptide levels and the severity of mitral regurgitation or accompanied by mild aortic valve dysfunction in children with rheumatic heart disease.

Children aged 1–18 years who had been identified as having rheumatic heart disease with a single mitral regurgitation or accompanied by mild aortic issues at Sanglah General Hospital, Denpasar, met the inclusion criteria for this cross-sectional study. Mitral regurgitation severity was determined using the parameters of vena contracta width, effective regurgitation orifice area, regurgitant jet area, and regurgitation volume. Bivariate analysis using the Spearman correlation test.

From 36 research subjects, the mean age was 11.32 years. In this study, there was a moderate positive correlation between the levels of N-terminal pro-brain natriuretic peptide and the regurgitation jet area. N-terminal pro-brain natriuretic peptide levels also had a moderately positive correlation with the vena contracta width and a weakly positive correlation with the regurgitation volume. Effective regurgitation orifice area and N-terminal pro-brain natriuretic peptide levels did not significantly correlate.

There was a moderately positive correlation between N-terminal pro-brain natriuretic peptide levels and the severity of mitral regurgitation on regurgitation jet area, a moderately positive correlation with the vena contracta width, and a weakly positive correlation with regurgitation volume in rheumatic heart disease patients.

The most serious manifestation of rheumatic fever is carditis, as it can lead to chronic rheumatic heart disease. Neutrophil-to-lymphocyte ratio, platelet-to lymphocyte ratio and mean platelet volume have been accepted as novel indicators of the continuing inflammation that is correlated with the severity of valvular involvement in patients with rheumatic carditis.

As a diagnostic study to investigate the correlation of neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and mean platelet volume with the severity of carditis in children with rheumatic fever.

This was a cross-sectional study at Sanglah Hospital, Bali. Data were collected retrospectively from medical records. Severity of carditis was characterised by a clinical, audible murmur during physical examination and demonstration of valvular involvement by echocardiography. Neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and mean platelet volume were calculated from complete blood count. The correlation between parameters was assessed using Spearman’s correlation tests.

From January 2018 to December 2020, we found 45 cases admitted to Sanglah Hospital. Carditis was present in 40 (88.9%) subjects. Neutrophil-to-lymphocyte ratio had a strong positive correlation with severity of carditis (r = 0.66, p = 0.001), while platelet-to-lymphocyte ratio had a weak positive correlation with the severity of carditis (r = 0.23, p = 0.13) and mean platelet volume had a very weak negative correlation with the severity of carditis (r = −0.01, p = 0.95). Using a cut-off of 3.4, neutrophil-to-lymphocyte ratio predicted severe carditis with a sensitivity of 81.8% and specificity of 91.3%.

There was a positive correlation between neutrophil-to-lymphocyte ratio and severity of carditis in children with rheumatic fever. Neutrophil-to-lymphocyte ratio might be used as a diagnostic tool to predict the diagnosis of carditis severity.