The predictive value of proBNP levels to determine the presence and severity of coronary artery disease in patients with a positive or inconclusive exercise stress test

Abstract

Background Several clinical studies have shown increased levels of N Terminal-Pronatriuretic Peptide (NT-proBNP) during epi- sodes of coronory ischaemia. Consistent with this observation, both Brain Natriuretic Peptide (BNP) and NT-proBNP correlated to severity, location, and extent of angiographic coronary artery disease (CAD). The main objective of this study was to identify the possible value of NT-proBNP level which indicates CAD. Methods Sixty patients with signs and symptoms of CAD were recruited for this study. They were divided into two groups; Group A, consisted of thirty patients with a positive Exercise Stress Test (EST) and Group B, consisted of thirty patients with an inconclusive EST. After the EST, all patients from both groups were required to have a NT-proBNP blood test, a left and right coronary angiogram and a left ventriculogram. Results Post EST NT-proBNP levels, in both groups, increased in the presence of CAD (p<0.001). For the positive EST group, the area under the ROC curve was 0.975 (p<0.001). A cut- off value of 120 pg/ml was identified with the highest sensitivity (95.7%) and specificity (100%). For patients in the inconclusive EST group, the area under the ROC curve was 0.912 (p<0.001). A cut-off value of 85 pg/ml was identified with the highest sensitivity (87.5%) and specificity (86.4%). Conclusion EST is relatively inaccurate at predicting CAD in patients with inconclusive ESTs. The need for an additional tool, such as NT-proBNP measurements post inconclusive EST is warranted in the determination of the presence of CAD.