Differential Diagnosis of Acute Dyspnea: The Usefulness of Tissue Doppler Echocardiography in Emergency Department by Emergnecy Physician

ABSTRACT

PURPOSE: In managing acutely dyspneic patients, differentiating the underlying disease rapidly is important but not easy. Although B-type natriuretic peptide (BNP) is generally accepted as a useful marker, inconclusive results require an emergency physician (EP) to have something more confirmative. We evaluate whether Tissue Doppler Echocardiography (TDE) performed by an EP can better discriminate between heart disease and lung disease than can BNP in the emergency department (ED). METHODS: For enrolled ED patients with acute dyspnea and unclear pathology, initial BNP level and TDE performed by EP were checked prospectively. The ratios of peak early diastolic transmitral blood flow velocity (E) versus the peak early diastolic tissue velocity over mitral annulus (Ea) on TDE were recorded. The sensitivity and specificity of tissue Doppler parameters and BNP levels for diagnosing acute heart failure were calculated and we compared the discriminatory ability of the two tools. RESULTS:49 patients (39 heart failure, 10 respiratory disease) were enrolled. The area under the ROC curves for BNP and E/Ea were 0.946 and 0.888 (p<0.001) respectively. Cutoff values were 350 pg/ml for BNP (sensitivity and specificity of 82.1% and 100%) and 9.0 for E/Ea (89.2% and 100%). Especially in the group with low BNP (<350), BNP was a poor discriminator of the underlying disease, whereas E/Ea was still effective (AUC 0.943, p=0.021). CONCLUSION: TDE by EP is a useful tool for diagnosing acute heart failure in ED and could easily and rapidly discriminate the underlying disease of acutely dyspneic patients, especially in patients with inconclusive BNP levels.