Correlation between Amino Terminal Pro Brain Natriuretic Peptide (NT-ProBNP) Level and Pulmonary Arterial Systolic Pressure in Patients with Pulmonary Hypertension

Background: Right heart catheterization is the gold standard for diagnosing and estimating pulmonary artery pressure in patients with pulmonary hypertension (PH). However, it is invasive, expensive and not amenable to repeated measurements that are necessary to monitor disease progression. Clinicians in Nepal mostly rely on the indirect measurement of pulmonary pressure via trans-thoracic echocardiography. Amino Terminal Pro Brain natriuretic Peptide (NT-proBNP) is found to be increased in proportion to the increased pulmonary artery pressure. Thus, this study aims to see the correlation of pulmonary artery pressure with NT-proBNP level. Since measurement of NT-proBNP is less expensive and easier to perform its repeated measurement can be used for monitoring disease progression and treatment outcome. Materials and Methods: Patients with Pulmonary Hypertension admitted under department of cardiology, Manmohan cardiothoracic vascular and transplant center were enrolled in this study over 6 months period. Cases were further divided into 3 different groups based on etiology of pulmonary hypertension into rheumatic heart disease (RHD), dilated cardiomyopathy (DCM) and COPD with corpulmonale. In all cases systolic and mean pulmonary artery pressure were measured by transthoracic echocardiography. Serum levels of NT-proBNP was measured in all the patients. SPSS ver. 20.0 was used to analyze the data. Spearman, Mann Whitney U and Kruskal Wallis tests were used for statistical analysis and statistical significance was established at ‘p' value less than 0.05. Result: A total of 91 PH diagnosed patients were enrolled in the study. The mean age of the total identified patient was 53.76 ± 15.5 yrs. A total of 31(34%) patients had primary diagnosis of corpulmonale, 30 (33%) had primary diagnosis of DCM and 30 (33%) were diagnosed with RHD. Majority of patients (34.1%) belonged to NYHA class III. Mean serum values of NT-proBNP was 175.27 + 163.38 pmol/L. Co-morbid conditions including, smoking, alcohol intake, advancing age, gender and diabetes mellitus were not found to be associated with NT-proBNP. Whereas hypertension showed significant relation with NT-proBNP. Mean serum values of NT-proBNP was higher in patients with DCM compared to RHD and corpulmonale. Mean serum values of NT-proBNP was significantly higher in patients of class IV NYHA grade. With decrease in LVEF, NT-proBNP was found to increase significantly. Serum NT-proBNP levels were compared with PASP which showed positive correlation (spearman's rs= .409, p=0). Conclusions: In this study PASP showed strong correlation with NT-proBNP. In patients with PH, PASP is difficult to estimate without either invasive or non-invasive techniques that require expertise and equipment. Although release of NT-proBNP is not the direct consequence of PH, its release and correlation with PASP can be clinically useful in estimating PASP in resource poor settings. The data in this study suggest that NT-proBNP may have potential as a marker of increased PASP in PH.