Use of N-terminal prohormone brain natriuretic peptide assay for etiologic diagnosis of acute dyspnea in elderly patients

Background B-type peptide assay (brain natriuretic peptide [BNP] and N-terminal prohormone brain natriuretic peptide [NT-proBNP]) is useful for the diagnosis of heart failure (HF), but few data are available on the use of these markers in elderly subjects. The aim of this study was to evaluate NT-proBNP assay for the diagnosis of acute left HF in patients older than 70 years hospitalized for acute dyspnea. Methods We prospectively enrolled 256 elderly patients with acute dyspnea. They were categorized by 2 cardiologists unaware of NT-proBNP values into a cardiac dyspnea subgroup (left HF) and a noncardiac dyspnea subgroup (all other causes). Results Mean age was 81 +/- 7 years, and 52% of the patients were women. The diagnoses made in the emergency setting were incorrect or uncertain in 45% of cases. The median NT-proBNP value was higher (P <.0001) in patients with cardiac dyspnea (n = 142; 7906 pg/mL) than in patients with noncardiac dyspnea (n = 112; 1066 pg/mL). The area under the receiver operating characteristic curve was 0.86 (95% CI 0.81-0.91). At a cutoff of 2000 pg/mL, NT-proBNP had a sensitivity of 86%, a specificity of 71%, and an overall accuracy of 80% for cardiac dyspnea. The use of 2 cutoffs (< 1200 and > 4500 pg/mL) resulted in an 8% error rate and a gray area englobing 32% of values. Conclusion NT-proBNP appears to be a sensitive and specific means of distinguishing pulmonary from cardiac causes of dyspnea in elderly patients. An optimal diagnostic strategy requires the use of 2 cutoffs and further investigations of patients with values in the gray area.