Plasma B-type natriuretic peptide (BNP) can reliably identify acute congestive heart failure (CHF) in patients presenting to the emergency department (ED) with acute dyspnea. Heart failure, asthma, and chronic obstructive pulmonary disease (COPD) are syndromes where dyspnea and wheezing are overlapping signs, and hence, these syndromes are often difficult to differentiate.
Objective: To determine whether BNP can distinguish new-onset heart failure in patients with COPD or asthma presenting with dyspnea to the ED.
Methods: The BNP Multinational Study was a seven-center prospective study of 1,586 adult patients presenting to the ED with acute dyspnea who had blinded BNP levels measured on arrival with a rapid, point-of-care device. This study evaluated the 417 patients with no previous history of heart failure and a history of asthma or COPD as a subgroup from the 1,586 adult patients in the BNP Multinational Study. The reference standard for CHF was adjudicated by two independent cardiologists, also blinded to BNP results, who reviewed all clinical data and standardized CHF scores.
Results: A total of 417 subjects (mean age 62.2 years, 64.4% male) had a history of asthma or COPD without a history of CHF. Of these, 87/417 (20.9%, 95% CI = 17.1% to 25.1%) were found to have CHF as the final adjudicated diagnosis. The emergency physicians identified a minority, 32/87 (36.8%), of these patients with CHF. The mean BNP values (+/- SD) were 587.0 +/- 426.4 and 108.8 +/- 221.3 pg/mL for those with and without CHF (p < 0.0001). At a cutpoint of 100 pg/mL, BNP had the following decision statistics: sensitivity 93.1%, specificity 77.3%, positive predictive value 51.9%, negative predictive value 97.7%, accuracy 80.6%, positive likelihood ratio 4.10, and negative likelihood ratio 0.09. If BNP would have been added to clinical judgment (high > or = 80% probability of CHF), at a cutpoint of 100 pg/mL, 83/87 (95.4%) of the CHF subjects would have been correctly diagnosed. Multivariate analysis found BNP to be the most important predictor of CHF (OR = 12.1, 95% CI = 5.4 to 27.0, p < 0.0001). In the 87 subjects found to have CHF, 39.0%, 22.2%, and 54.8% were taking angiotensin-converting enzyme inhibitors (ACEIs), beta-blockers (BBs), and diuretics on a chronic basis, respectively.
Conclusions: The yield of adding routine BNP testing in patients with a history of asthma or COPD in picking up newly diagnosed CHF is approximately 20%. This group of patients presents a substantial therapeutic opportunity for the initiation and chronic administration of ACEI and BB therapy, as well as other CHF management strategies.