Measuring B-type natriuretic peptide (BNP) at the bedside was more accurate than any physical exam finding or other lab test for diagnosing heart failure in emergency patients with shortness of breath.
96% negative predictive valueBNP levels below 50 pg/mL effectively ruled out heart failure in ER patients with shortness of breath — making it a powerful 'rule-out' test
What the researchers found
In a prospective study of 1,586 emergency department patients presenting with acute dyspnea, B-type natriuretic peptide (BNP) measured by bedside assay was more accurate than any historical finding, physical examination, or laboratory value for identifying congestive heart failure.
At a cutoff of 100 pg/mL, BNP had a diagnostic accuracy of 83.4%. At levels below 50 pg/mL, the negative predictive value was 96% — meaning very low BNP effectively rules out heart failure. Of the patients studied, 47% had heart failure, 49% had non-cardiac causes of dyspnea, and 5% had dyspnea from non-cardiac causes despite a history of left ventricular dysfunction. BNP added significant independent predictive power to other clinical variables in multivariate analysis.
Why it matters
This study, published in the New England Journal of Medicine, was one of the most influential papers establishing BNP testing as a standard tool in emergency medicine. Before bedside BNP testing, distinguishing heart failure from other causes of shortness of breath relied heavily on clinical judgment, chest X-rays, and time-consuming workups. A simple, rapid blood test that outperforms clinical assessment fundamentally changed how heart failure is diagnosed in the acute setting.
How the study worked
Prospective, multicenter study enrolling 1,586 patients who presented to emergency departments with acute dyspnea (shortness of breath). BNP was measured using a bedside point-of-care assay. The final diagnosis of congestive heart failure was adjudicated by two independent cardiologists who were blinded to the BNP results, providing an unbiased gold standard for comparison.
What this study cannot tell us
The 83.4% accuracy means roughly 1 in 6 patients could be misclassified. BNP levels can be elevated in conditions other than heart failure (kidney disease, pulmonary embolism, sepsis), leading to false positives. Obesity can suppress BNP levels, potentially causing false negatives. The study population was from emergency departments, so results may not generalize to outpatient or primary care settings. The optimal cutoff value has been debated since publication.
How to read the evidence
This is a large, prospective, multicenter diagnostic study published in the New England Journal of Medicine with blinded adjudication. It represents high-quality evidence for BNP's diagnostic utility and has been extensively validated in subsequent studies.
When this study was published
Published in 2002, this is a foundational study that changed emergency medicine practice. While over two decades old, its findings have been validated many times over and BNP testing is now standard of care worldwide.
The bigger picture
BNP is a naturally occurring peptide hormone — it's released by the heart's ventricles when they're stretched by excess fluid. This study turned a biological signal into a diagnostic tool and helped launch the era of peptide biomarkers in cardiology. Today, BNP and its precursor NT-proBNP are among the most commonly ordered blood tests in emergency departments worldwide, directly influencing treatment decisions for millions of patients annually.
Questions still open
- How should BNP cutoff values be adjusted for patients with obesity, renal disease, or other conditions that affect BNP levels?
- Does BNP-guided triage in the emergency department reduce hospital length of stay or improve patient outcomes?
- How does NT-proBNP compare to BNP for emergency diagnosis of heart failure?
Common questions
What is BNP and why does the heart release it?
Is the BNP test still used today?
Read the original research
Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure.
The New England journal of medicine, 347(3), 161-7
Citation
Maisel, Alan S; Krishnaswamy, Padma; Nowak, Richard M; McCord, James; Hollander, Judd E; Duc, Philippe; Omland, Torbjørn; Storrow, Alan B; Abraham, William T; Wu, Alan H B; Clopton, Paul; Steg, Philippe G; Westheim, Arne; Knudsen, Catherine Wold; Perez, Alberto; Kazanegra, Radmila; Herrmann, Howard C; McCullough, Peter A. (2002). Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure.. The New England journal of medicine, 347(3), 161-7.