Comparison of midregional pro-atrial natriuretic peptide with N-terminal pro-B-type natriuretic peptide in the diagnosis of heart failure

Objectives. The concentration of atrial natriuretic peptide (ANP) in the circulation is approximately 10- to 50- fold higher than B-type natriuretic peptide (BNP). We sought to compare the accuracy of midregional pro-atrial natriuretic peptide (MRproANP) measured with a novel sandwich immunoassay with N-terminal pro-B-type natriuretic peptide (NTproBNP) in the diagnosis of heart failure. Design. The diagnosis of heart failure was adjudicated by two independent cardiologists using all available clinical data (including BNP levels) in 287 consecutive patients presenting with dyspnoea to the emergency department (ED). MRproANP and NTproBNP levels were determined at presentation in a blinded fashion. Results. Heart failure was the adjudicated final diagnosis in 154 patients (54%). Median MRproANP was significantly higher in patients with heart failure as compared to patients with other causes of dyspnoea (400 vs. 92 pmol L-1, P < 0.001). The diagnostic accuracy of MRproANP was very high with an area under the receiver operating characteristic curve of 0.92 and was comparable with that of NTproBNP (0.92, P = 0.791). Moreover, MRproANP provided incremental diagnostic information to BNP and NTproBNP in patients presenting with BNP levels in the grey zone between 100 and 500 pg mL-1. Conclusion. Midregional pro-atrial natriuretic peptide is as accurate in the diagnosis of heart failure as NTproBNP. MRproANP seems to provide incremental information on top of BNP or NT-proBNP in some subgroups and should be further investigated in other studies.