Aims: Plasma brain natriuretic peptide (BNP) concentration increases in proportion to heart failure (HF) severity. Although plasma BNP decreases to a certain level by optimal treatment, there is significant heterogeneity in the baseline value among individuals. The underlying mechanism of the steady-state plasma BNP levels remains still controversial. We investigated the hypothesis that myocardial stiffness (K(m)) is a major determinant of the plasma BNP level.
Methods and results: In 19 patients with diastolic HF [DHF; left ventricular ejection fraction (LVEF) > or =4 5%], 18 with systolic HF (SHF; LVEF < 45%), and 12 controls, left ventricular (LV) performance variables and the results of the stress-strain analyses were obtained by the combined simultaneous measurement of echocardiographic and haemodynamic data, and compared with the plasma BNP level. In DHF, a significant correlation was observed between plasma BNP and fractional shortening (P = 0.010), pulmonary capillary wedge pressure (P = 0.030), end-diastolic pressure (P = 0.006), time constant of the LV isovolumic-pressure decline (P = 0.049), end-diastolic stress (P = 0.012), and K(m) (P = 0.004), respectively. In SHF, a significant correlation was observed between plasma BNP and end-diastolic stress (P = 0.036), chamber stiffness (P = 0.048), and K(m) (P = 0.003), respectively.
Conclusion: In stable conditions, K(m) may be the most important determinant of the plasma BNP production in patients with both DHF and SHF.