The utility of B-type natriuretic peptide in differentiating decompensated heart failure from lung disease in patients presenting to the emergency department with dyspnea

Background

Differentiating congestive heart failure (CHF) from lung disease is extremely important in patients evaluated in the emergency department (ED). Therefore we sought to assess the utility of B-type natriuretic peptide (BNP), which is secreted by the left ventricle in response to volume or pressure overload, in differentiating CHF from lung diseases in elderly patients presenting to the ED with acute dyspnea.

Methods

From April to July 2001, 70 patients presenting to the ED of a tertiary cardiology hospital with acute dyspnea were included. Mean age was 72 ± 16 years and 33 (47%) were male. BNP was measured in all patients at the moment of admission in the ED using a rapid bedside test. Emergency-care physicians were required to assign a probable diagnosis, blinded to BNP values. A cardiologist retrospectively reviewed patients' data (blinded to BNP measurements) and assigned a diagnosis that was considered the gold standard to assess the diagnostic performance of the BNP test.

Results

The mean BNP concentration was higher in patients with CHF (n = 36) than it was in patients with lung diseases (n = 29). Such values were 990 ± 550 vs 112 ± 59 pg/ml, respectively (P < 0.001). The pulmonary diseases and their respective BNP levels were: chronic obstructive pulmonary disease, 98 ± 69 pg/ml (n = 5); asthma, 38 ± 30 pg/ml (n = 3); acute pulmonary embolism, 158 ± 35 pg/ml (n = 2); and pneumonia, 80 ± 52 pg/ml (n = 19). In patients with a history of lung disease but whose current complaint of dyspnea was found to be CHF, BNP levels were 898 ± 456 pg/ml. Those patients with a history of CHF but a current diagnosis of pulmonary disease had a BNP of 98 ± 47 pg/ml. The area under the receiver operating curve for BNP levels in differentiating CHF from lung diseases was 0.98.

Conclusion

A rapid bedside test for BNP is useful in differentiating lung diseases from decompensated CHF in elderly patients presenting to the ED with dyspnea.