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Amino-terminal pro-brain natriuretic peptide for the diagnosis of acute heart failure in patients with previous obstructive airway disease.

Tung RH, Camargo CA, Krauser D, Anwaruddin S, Baggish A, Chen A, Januzzi JL

Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.

STUDY OBJECTIVE: We evaluate results from amino-terminal pro-brain natriuretic peptide (NT-proBNP) testing with or without those of clinical judgment for the evaluation of dyspneic patients with previous chronic obstructive pulmonary disease or asthma. METHODS: As a secondary analysis of previously collected observational data from a convenience sample of 599 breathless patients, 216 patients with previous chronic obstructive pulmonary disease or asthma who presented to the emergency department were analyzed according to results of NT-proBNP, clinical impression, and their final diagnosis. Test performance of NT-proBNP in these patients with chronic obstructive pulmonary disease or asthma was examined for the group as a whole, as well as in patients with and without previous heart failure. NT-proBNP results were compared to clinician-estimated likelihood for heart failure using receiver operating curves and as a function of NT-proBNP plus clinical evaluation. The final diagnosis was determined by 2 independent cardiologists blinded to NT-proBNP using all available data from the 60-day follow-up period. RESULTS: Overall, 55 patients (25%) had acute heart failure; the median value of NT-proBNP was higher in these patients compared with those without acute heart failure (2,238 vs 178 pg/mL); use of cut points of 450 pg/mL for patients younger than 50 years and 900 pg/mL for patients 50 years or older yielded a sensitivity of 87% (95% confidence interval [CI] 72% to 93%) and a specificity of 84% (95% CI 76% to 88%). In patients without previous heart failure (n=164), median NT-proBNP levels were also higher in patients with heart failure of new onset compared with those with chronic obstructive pulmonary disease or asthma exacerbation (1561 versus 168 pg/mL). High clinical suspicion for acute heart failure (probability >80%) detected only 23% of patients with new-onset heart failure, whereas 82% of these patients had elevated NT-proBNP levels. In patients who had both previous acute heart failure and chronic obstructive pulmonary disease or asthma (n=52), median NT-proBNP levels were significantly higher in those with acute heart failure (4,435 pg/mL) than patients with chronic obstructive pulmonary disease or asthma exacerbation (536 pg/mL). In patients with acute-on-chronic heart failure, NT-proBNP levels were elevated in 91%, whereas clinical impression considered only 39% of cases as high likelihood for acute heart failure. CONCLUSION: NT-proBNP may be a useful adjunct to standard clinical evaluation of dyspneic patients with previous obstructive airway disease.

Published 19 June 2006 in Ann Emerg Med, 48(1): 66-74.
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