Differential Diagnosis of Right Heart Failure and Left Heart Failure in Acute Dyspnea: The Meaning of N-terminal Probrain Natriuretic Peptide (NTproBNP)

Lee, Young Ju; Baek, Kwang Je; Lee, Kyeong Ryong; Ki, Woong

Abstract

PURPOSE: Right heart failure (RHF) is not a infrequant disease entitiy, but it is difficult to diagnose and mortality rate increases with worsening right heart failure. The utility of Nterminal pro-brain natriuretic peptide (NT-proBNP) testing in the emergency department for differentiating right heart failure from left heart failure (LHF), and optimal cut-off points for its use, are not well established.
METHODS
One hundred thirty-six consecutive patients with acute dyspnea, who visited our emergency medical center from August 2005 to August 2006 were recruited prospectively. Patients with acute coronary syndrome and chronic renal failure were excluded. The diagnosis of RHF was based on echocardiographic evidence of right ventricular dysfunction. The diagnostic accuracy of NT-proBNP was assessed by receiver operating characteristic curve analysis.
RESULTS
The mean patient age was 68+/-13 years, and 64% were women. The median NT-proBNP level among 68 patients (50%) who had LHF and 29 patients (21%) who had RHF were 2524 1572 pg/ml, respectively, versus 520 pg/ml for 39 patients (29%) who did not have heart failure (HF) (p = 0.01). NT-proBNP levels correlated well with right ventricular systolic pressure. However, although patients with RHF exhibited significantly higher NT-proBNP levels than did patients without HF, NT-proBNP levels did not differentiate left from right heart failure. The area under the receiver operating characteristic curve was 0.71 (95% CI 0.63~0.85). At a cutoff of 700 pg/ml, NT-proBNP had a sensitivity of 68%, a specificity of 35%, an overall accuracy of 58%, a false negative rate of 32%, a false positive rate of 66% in differentiating between LHF from RHF (p = 0.03).
CONCLUSION
NT-proBNP is elevated in majority of cases of right heart failure, but NT-proBNP could not differentiate RHF from LHF. Therefore, this underscores that NTproBNP is not a stand-alone test and that correct clinical evaluation and echocardiography is still of highest importance.