According to the 2004 American College of Cardiology (ACC) expert BNP consensus: if BNP <100 ng/L, the likelihood of heart failure is extremely low, and its negative predictive value is 90%, and if BNP >500 ng/L, the likelihood of heart failure is extremely high, and its positive predictive value is 90%. Currently, BNP has been used as an independent diagnostic criterion for heart failure in clinical practice. According to the New York Heart Association Heart Failure Classification Criteria (NYHA classification), BNP <80 ng/L in patients without heart failure, BNP 95-221 ng/L in patients with cardiac function class I, BNP 221-459 ng/L in patients with cardiac function class II, BNP 459-1006 ng/L in patients with cardiac function class III, and BNP ≥1006 ng/L in patients with cardiac function class IV. Currently, the positive threshold for BNP in heart failure patients is set at 100 ng/L internationally, and when BNP measurements are below normal, heart failure can be considered to be ruled out.