Potential Role of NT-proBNP and Tissue Doppler Indices to Assess the Severity of Rheumatic Heart Disease: A Cross-sectional Study

Abstract

Introduction: Rheumatic Heart Disease (RHD) remains the primary cause of acquired Valvular Heart Disease (VHD) in developing countries. The role of Tissue Doppler Indices (TDI) in RHD is understudied. This study aims to fill evidence gaps identified by the American College of Cardiology/American Heart Association in the management of Valvular Heart Disease (VHD) by analysing newer echocardiographic techniques {Tissue Doppler Imaging (TDI)} and biochemical markers (NT-proBNP) against clinical parameters {New York Heart Association (NYHA)} in an understudied patient group. Aim: To evaluate the role of TDI and its association with the functional class of dyspnoea and serum NT-proBNP levels in RHD. Materials and Methods: This cross-sectional study was conducted in the Cardiology and Medicine departments, Central Gujarat, Western India, from January 2021 to June 2022. Fifty-seven consenting adult patients with RHD who underwent echocardiography with Standard Echocardiographic Techniques (SET) to stratify VHD severity were included. Patients were divided into three sub-groups: a) Isolated MR and MR with mild/moderate MS (n=23); b) Isolated MS and MS with mild MR (n=29); and c) Isolated MS and MS with mild or moderate MR (n=48). TDI parameters (e’, a’, e’/a’, and E/e’) at medial mitral, lateral mitral, and tricuspid annuli, NYHA classification, and serum NT-proBNP levels were analysed. The Analysis of Variance (ANOVA) was used to assess the association between NYHA class and clinical and NT-proBNP parameters. The Pearson correlation coefficient was employed to determine linear relationships between NT-proBNP and TDI parameters. Results: The mean age was 45.4±16 years, with the age groups 20-40 years (n=20) and 40-60 years (n=22) having a nearly equal distribution. The female-to-male ratio was 1.48 (34/23). In subgroup C, the a’ velocity decreased from 13.74±3.92 cm/s in NYHA I to 5.17±1.98 cm/s in NYHA IV (p=0.0312), and the e’/a’ ratio increased from 0.96±0.40 in NYHA I to 2.41±1.00 in NYHA IV (p=0.0210). These changes paralleled trends in a’ value (p=0.0306) and e’/a’ ratio (p=0.0157) with increasing NTproBNP levels. Conclusion: At the tricuspid annulus, the e’/a’ ratio and a’ velocity can complement NT-proBNP in cases where there is a discrepancy between the clinical status of the patient and the severity of the valve lesion as determined by SET. Larger-scale studies are needed to further evaluate the association between TDI parameters and long-term clinical outcomes, as well as to identify the optimal timing for surgical intervention in RHD patients.