The influence of confounders in the analysis of mid-regional pro-atrial natriuretic peptide in patients with chronic heart failure.

Background: Natriuretic peptides play an important role in the diagnosis and risk stratification of patients with acute and chronic heart failure. Multiple studies have shown that these peptides are liable to the influence of individual factors. For N-terminal-pro-B-type natriuretic peptide (NT-proBNP) some of these confounding factors have been evaluated over the years such as age, gender, New York Heart Association (NYHA) class and body mass index (BMI). The aim of this study was to establish confounding factors of mid-regional pro-atrial natriuretic peptide (MR-proANP) assessment.

Methods And Results: We studied 684 patients (94% male, age 61.2±11.2, left ventricular ejection fraction [LVEF]<35%-45%, NYHA class (I/II/III/IV: 8.4/45.8/39.5/6.3%), ischaemic aetiology 71%, body mass index [BMI] 26.5±4.3kg/m(2), mean MR-proANP 296.0±281.0pmol/L, mean NT-proBNP 2792.0±5328.6pg/mL, mean creatinine level 110.2±38.0μmol/L and mean haemoglobin 13.9±1.5g/dL) with clinically stable chronic heart failure. MR-proANP levels increased with increasing NYHA class (p<0.0001) and an increasing BMI category was associated with decreasing values of MR-proANP (p<0.0001). We found MR-proANP to be independently associated with BMI, creatinine, ischaemic aetiology, LVEF and NYHA class. Meanwhile, NT-proBNP was independently associated with BMI, creatinine, haemoglobin, LVEF and NYHA class.

Conclusion: MR-proANP is subject to the almost identical influencing factors like NT-proBNP. The effects of anaemia warrant further study.