Correlation between serial measurements of N-terminal pro brain natriuretic peptide and ambulatory cardiac filling pressures in outpatients with chronic heart failure

Background: Serial measurements of N-terminal pro brain natriuretic peptide (NT-proBNP) have been suggested for the management of outpatients with chronic heart failure (CHF). The relationship between NT-proBNP plasma levels and central haemodynamic parameters in this setting is not known. Methods: In 19 outpatients with CHF, NT-proBNP was related to central haemodynamic information, continuously measured with an implanted haemodynamic monitor (IHM) during 24 h of daily living activities ("24 h") and during supine rest ("rest"). In 13 patients, three to seven serial measurements were obtained with a mean time interval of 39 days (range 19-113). Results: At the first visit (n = 19), NT-proBNP plasma levels were dispersed over a wide range of filling pressures and not correlated with the 24 h median of the right ventricular systolic pressure (RVSP) and the estimated pulmonary artery pressure (ePAD). However, in the individual patient, serial measurements yielded significant positive correlations between NT-proBNP and RVSP (p = 0.006) and ePAD (p = 0.001). During "24 h" compared with "rest", the median RVSP and ePAD were elevated by 20 ± 16% and 32 ± 18%, respectively, and corresponded better with NT-proBNP (p <0.05). Conclusion: In outpatients with CHF, single measurements of NT-proBNP are not correlated with cardiac filling pressures. However, serial measurements of NT-proBNP in each individual patient show a significant positive correlation with central haemodynamic parameters and reflect changes in the haemodynamic state over time.