Possible Mechanisms Underlying Elevated Serum N-Terminal Pro-Brain Natriuretic Peptide in Healthy Japanese Subjects

The precise mechanisms underlying elevation of serum N-terminal pro-brain natriuretic peptide (NT-proBNP) in healthy subjects have not been fully clarified. In 2,844 Japanese healthy subjects with serum NT-proBNP <125 pg/mL, (1) brachial-ankle pulse wave velocity and (2) second peak of the peripheral systolic blood pressure minus diastolic blood pressure (pulse pressure 2 [PP2]), as markers of cardiac afterload; (3) fibrosis 4 score (FIB-4 score, a marker of liver fibrosis), as a marker of cardiac preload; and (4) ratio of the pre-ejection time to ejection time (PEP/ET), as a marker of cardiac systolic function, were measured. At the first examination, after the adjustments, log-transformed serum NT-proBNP was associated with PP2 and FIB-4 score, but not with PEP/ET. These parameters were successfully measured again after a 3-year interval in 1,978 subjects. On Pearson's correlation analysis, change in PP2 and FIB-4 score during the study period was significantly correlated with change in serum NT-proBNP (r=0.05, 0.09, respectively; P<0.01). In apparently healthy Japanese subjects, both increased cardiac preload and increased cardiac afterload, but not impaired cardiac systolic function, may be associated with elevated serum NT-proBNP.