Comparative value of Doppler echocardiography and B-type natriuretic peptide assay in the etiologic diagnosis of acute dyspnea

Objectives We compared the accuracy of B-type natriuretic peptide (BNP) assay with Doppler echocardiography for the diagnosis of decompensated congestive left-heart failure (CHF) in patients with acute dyspnea. Background Both BNP and Doppler echocardiography have been described as relevant diagnostic tests for heart failure. Methods One hundred sixty-three consecutive patients with severe dyspnea underwent BNP assay and Doppler echocardiogram on admission. The accuracy of the two methods for etiologic diagnosis was compared on the basis of the final diagnoses established by physicians who were blinded to the BNP and Doppler findings. Results The final etiologic diagnosis was CHF in 115 patients. Twenty-four patients (15%) were misdiagnosed at admission. The BNP concentration was 1,022 ± 742 pg/ml in the CHF subgroup and 187 ± 158 pg/ml in the other patients (p < 0.01). A BNP cutoff of 300 pg/ml correctly classified 88% of the patients (odds ratio [OR] 85 [19 to 376], p < 0.0001), but a high negative predictive value (90%) was only obtained when the cutoff was lowered to 80 pg/ml. The etiologic value of BNP was low in patients with values between 80 and 300 pg/ml (OR 1.85 [0.4 to 7.8], P = 0.4) and also in patients who were studied very soon after onset of acute dyspnea. Among the 138 patients with assessable Doppler findings, a “restrictive” mitral inflow pattern had a diagnostic accuracy for CHF of 91% (OR 482 [77 to 3,011], p < 0.0001), regardless of the BNP level. Conclusions Bedside BNP measurement and Doppler echocardiography are both useful for establishing the cause of acute dyspnea. However, Doppler analysis of the mitral inflow pattern was more accurate, particularly in patients with intermediate BNP levels or “flash” pulmonary edema.