Diagnostic Accuracy of BNP Levels in Detection of Heart Failure

Objective: Evaluation of serum Brain Natriuretic Peptide levels as screening test in the diagnosis of left ventricular failure or congestive heart failure Material and methods: This cross-sectional survey was conducted at the Department of Medicine, Nishtar Hospital and Ch Parvez Ellahi Institute of Cardiology Multan from Feb 2006 to August 2006. A total of 50 patients were studied. Sampling was performed by non probability convenient type sampling technique. Results: Out of the 50 patients, 47(94%) patients had ejection fraction of less than 45% and were diagnosed as cardiac failure, as confirmed by echocardiography. Among these cases BNP levels were found to be elevated in 36(72%) patients, whereas in 11 (22%) cases, BNP levels were falsely negative. Only 3 patients (6%) in whom initial clinical diagnosis was heart failure, were later found to have negative echocardiography (EF > 45%). Two patients (4%) with negative echocardiography (EF > 45%), had the BNP levels also negative i.e. below the cut-off point, whereas BNP was falsely positive in 1 patient Sensitivity and specificity of BNP (by ELISA) was found to be 80% and 66% respectively and accuracy was 80%. Conclusion: BNP measurements in the blood, is a new technique to diagnose heart failure. The clinical sensitivity and specificity of BNP (by ELISA) was although lower than echocardiography but it can be a good alternative for echocardiography.