Diversity of molecular forms of plasma brain natriuretic peptide in heart failure—different proBNP-108 to BNP-32 ratios in atrial and ventricular overload

ObjectiveRecent studies have shown that plasma levels of brain natriuretic peptide (BNP)-32 and proBNP-108 are increased in heart failure (HF) and that the BNP-32 assay kit in current clinical use cross-reacts with proBNP-108. We investigated why proBNP is increased without processing in HF was investigated.Design, setting and patientsPlasma BNP-32 and proBNP-108 in normal individuals (n=10) and in patients with atrial fibrillation (AF) (n=18) and HF (n=132) was measured. BNP-32 and proBNP-108 in ventricular and atrial tissue and in pericardial fluid using a specific fluorescent enzyme immunoassay following Sep-Pak C18 (Waters, Milford, Massachusetts, USA) cartridge extraction and gel filtration was also measured.Main outcome measuresLevels of both BNP-32 and proBNP-108 were higher in HF than in control or AF (both p