Comparison of BNP and NT-proBNP in Patients With Heart Failure and Reduced Ejection Fraction

BACKGROUND: Both BNP (B-type natriuretic peptide) and NT-proBNP (N-terminal pro B-type natriuretic peptide) are widely used to aid diagnosis, assess the effect of therapy, and predict outcomes in heart failure and reduced ejection fraction. However, little is known about how these 2 peptides compare in heart failure and reduced ejection fraction, especially with contemporary assays. Both peptides were measured at screening in the PARADIGM-HF trial (Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure).

METHODS: Eligibility criteria in PARADIGM-HF included New York Heart Association functional class II to IV, left ventricular ejection fraction ≤40%, and elevated natriuretic peptides: BNP ≥150 pg/mL or NT-proBNP ≥600 pg/mL (for patients with HF hospitalization within 12 months, BNP ≥100 pg/mL or NT-proBNP ≥400 pg/mL). BNP and NT-proBNP were measured simultaneously at screening and only patients who fulfilled entry criteria for both natriuretic peptides were included in the present analysis. The BNP/NT-proBNP criteria were not different for patients in atrial fibrillation. Estimated glomerular filtration rate <30 mL/min per 1.73 m2 was a key exclusion criterion.

RESULTS: The median baseline concentration of NT-proBNP was 2067 (Q1, Q3: 1217-4003) and BNP 318 (Q1, Q3: 207-559), and the ratio, calculated from the raw data, was ≈6.25:1. This ratio varied considerably according to rhythm (atrial fibrillation 8.03:1; no atrial fibrillation 5.75:1) and with age, renal function, and body mass index but not with left ventricular ejection fraction. Each peptide was similarly predictive of death (all-cause, cardiovascular, sudden and pump failure) and heart failure hospitalization, for example, cardiovascular death: BNP hazard ratio, 1.41 (95% CI, 1.33-1.49) per 1 SD increase, P<0.0001; NT-proBNP, 1.45 (1.36-1.54); P<0.0001.

CONCLUSIONS: The ratio of NT-proBNP to BNP in heart failure and reduced ejection fraction appears to be greater than generally appreciated, differs between patients with and without atrial fibrillation, and increases substantially with increasing age and decreasing renal function. These findings are important for comparison of natriuretic peptide concentrations in heart failure and reduced ejection fraction.