B-type natriuretic peptide and echocardiographic determination of ejection fraction in the diagnosis of congestive heart failure in patients with acute dyspnea

Background: Echocardiography and B-type natriuretic peptide (BNP) are diagnostic tests for congestive heart failure (CHF), but an emergency diagnosis can be difficult. Objective: To assess the diagnostic performance of BNP testing and echocardiographic assessment of left ventricular systolic function, separately and combined, for the identification of CHF in patients with acute dyspnea. Design: Prospective, multinational, multicenter study. Setting: Patients presenting to emergency departments in seven hospitals between June 1999 and December 2000. Patients: A total of 1,586 patients with acute dyspnea. Main outcome measures: Echocardiographic determination of ejection fraction (EF) and point-of care BNP measurement for the diagnosis of CHF. Results: Seven hundred nine of the 1,586 patients underwent echocardiography; 492 patients (69.4%) had a final diagnosis of CHF. Patients with CHF were older (68.5 years vs 61.6 years, p < 0.0001), had a lower EF (39.5% vs 56.1%, p < 0.0001), and a higher BNP (683 pg/mL vs 129 pg/mL, p < 0.0001) than patients without CHF. Area under the receiver operating characteristic (ROC) curve for the diagnosis of CHF was significantly higher for BNP (0.89) than for EF (0.78; area under the ROC curve difference, 0.12; p < 0.0001). The sensitivity of BNP >= 100 pg/mL for the diagnosis of CHF was 89%, and specificity was 73%. Values for EF <= 50% had a sensitivity of 70% and a specificity of 77%. Multivariate logistic regression analysis showed that, in combination with clinical, ECG, and chest radiograph data, BNP 2: 100 pg/mL and EF:5 50% remained independent predictors of CHF (odds ratios, 32.1 and 6.2, respectively). The proportions of patients who were correctly classified were 67% for BNP alone, 55% for EF alone, 82% for the two variables together, and 97.3% when clinical, ECG, and chest radiograph data were added. Conclusion: BNP measurement was superior to two-dimensional echocardiographic determination of EF in identifying CHF, regardless of the threshold value. The two methods combined have marked additive diagnostic value.