B-type natriuretic peptide and high sensitivity C-reactive protein in patients with rheumatic fever and rheumatic heart disease: relationship to mitral regurgitation

Introduction
Rheumatic fever (RF) is one of the leading causes of cardiac disease in developing countries. Brain natriuretic peptide (BNP) is a cardiovascular hormone emitted from the myocardium of the ventricles as a reaction to pressure overload and the expansion of ventricular volume. High sensitivity C reactive protein (hsCRP) levels are increased in several inflammatory and cardiac diseases. We aimed to study the relationship between BNP and hsCRP levels and the presence of rheumatic heart disease (RHD) and to investigate their levels as indices of the severity of chronic rheumatic mitral regurgitation (MR).

Material and methods
Seventy-seven Egyptian patients with RF and 43 age and gender-matched healthy controls were included in the study. The two groups of the RF patients were: RHD, group (n = 62) diagnosed by transthoracic echocardiogram detecting the rheumatic involvement of the mitral valve, and rheumatic fever only (RFo) group (n = 15) had a history of RF without the presence of RHD. Serum BNP levels were measured by enzyme-linked immunoassay, while hsCRP levels were measured by the immunometric assay.

Results
Both serum BNP and hsCRP levels were higher in RHD groups than in the controls (p = 001 and p = 0.018, respectively). Serum BNP levels were elevated in the RHD patients than in the RFo patients (p = 0.01). Both BNP and hsCRP levels were correlated positively with echocardiographic parameters of the severity of MR (p = 0.001). The cut-off value of BNP levels of 9.02 ng/ml with sensitivity 67.7% and specificity 85.4% was associated with the risk of RHD. No correlation was found between BNP levels and the duration of RHD.

Conclusions
The serum BNP levels and hsCRP levels appear to be significantly associated with the RHD and the MR severity.