What is B-type Natriuretic Peptide (BNP) used for in heart failure?

BNP in Heart Failure: Diagnostic and Prognostic Applications

B-type Natriuretic Peptide (BNP) is primarily used for diagnosing heart failure, risk stratification, and monitoring treatment response in patients with heart failure. 1, 2

Diagnostic Applications

• BNP serves as a valuable diagnostic tool for heart failure with established cutoff values:

  • BNP <100 pg/mL: Heart failure is unlikely (high negative predictive value) 1, 2
  • BNP 100-500 pg/mL: Grey zone requiring clinical correlation 1
  • BNP >500 pg/mL: Heart failure is likely 1

• NT-proBNP (N-terminal pro-B-type natriuretic peptide) has age-specific diagnostic thresholds:

  • <300 pg/mL: Rules out heart failure with 98% negative predictive value 1, 3
  • Age-specific rule-in values: >450 pg/mL (<50 years), >900 pg/mL (50-75 years), >1800 pg/mL (>75 years) 1, 3

• BNP testing is most valuable in patients with intermediate pre-test probability of heart failure, particularly in emergency settings for patients presenting with acute dyspnea 1, 2

Prognostic Value

• BNP measurements during hospitalization are powerful independent predictors of mortality and morbidity in heart failure patients 1
• Higher BNP levels correlate with increased mortality risk - each 100 pg/mL increase is associated with approximately 35% higher relative risk of death 2, 4
• Pre-discharge BNP is an independent marker of death or readmission 1
• A reduction in BNP level by >30% during treatment is associated with improved survival 1

Treatment Monitoring

• BNP can be used to guide heart failure therapy and monitor treatment response 2, 5
• BNP-guided therapy may reduce all-cause mortality in patients with chronic heart failure, especially in those >75 years 1
• A goal to maintain BNP <100 pg/mL correlates with functional improvement and may decrease clinical endpoints such as cardiovascular death 5, 6
• Rising BNP levels may indicate treatment failure or disease progression 2, 6

Factors Affecting BNP Interpretation

• Renal function: Reduced glomerular filtration rate (<60 mL/min/1.73m²) elevates BNP levels 1, 3
• Obesity: BMI >35 kg/m² is associated with lower BNP levels, potentially masking cardiac dysfunction 1, 2
• Age: BNP levels increase with age, requiring age-adjusted thresholds 1, 3
• BNP cannot distinguish between systolic and diastolic heart failure, though values tend to be lower in diastolic heart failure 1

Clinical Applications Beyond Heart Failure

• BNP helps identify high-risk patients with acute pulmonary embolism 1
• Elevated pre-operative BNP predicts post-operative cardiovascular events in non-cardiac surgery 1
• BNP correlates with severity of aortic stenosis and predicts outcomes after valve surgery 1, 2

Common Pitfalls

• Relying solely on BNP without clinical context or confirmatory imaging 2, 3
• Using BNP for routine screening in asymptomatic populations 2, 3
• Failing to consider factors that affect BNP levels (age, renal function, obesity) 1, 2
• Expecting tight correlations between BNP levels and hemodynamic parameters or ejection fraction 2, 3

BNP and NT-proBNP are complementary biomarkers with similar diagnostic and prognostic performance, though subtle differences exist in their clinical correlates 7, 8. Both serve as the most powerful independent markers of outcome in heart failure patients 7, 6.