BASEL Study on the role of BNP estimation in heart failure has shown that BNP as a diagnostic test for heart failure can avoid several unnecessary admissions. BNP values less than 100 pg/ml have a 98% negative predictive value. BNP levels in highest quartile of VALHEFT trial were associated with highest mortality.
70% reduction in BNP at discharge has a good correlation with good 6 month prognosis. There is direct correlation between the reduction of pulmonary capillary wedge pressure and BNP levels as patient improves with treatment. In heart failure patients treated on an outpatient basis, 50% rise of BNP levels from the basal levels indicate need for in patient treatment. In paediatric patients in whom differentiation of heart failure from dyspnoea due to respiratory infection is difficult, BNP is very useful.
False positive BNP can occur in old age, renal failure, myocardial infarction and cor pulmonale. False negative BNP can occur in obesity, flash pulmonary edema (BNP elevation may be delayed) and mitral stenosis (heart failure without dilatation of left ventricle).