Abstract

Objectives: This study examines N-terminal pro-brain natriuretic peptide (NT-proBNP) variability in plasma and urine samples of stable heart failure patients during a 24-month follow-up.

Design: prospective study

Setting: Teaching hospital based study Patients: We followed 74 clinically and functionally stable patients (NYHA class=2±0.5) out of 114 diagnosed of heart failure, measuring NT-proBNP plasma and urine levels in three stages (basal, 12 months and 24 months).

Results: During the follow-up we found significant differences in mean urinary levels (p<0.01), but no changes were found in plasma. Bland-Altman plots showed few variations in plasma percentages in the three intervals (stage I - basal; stage II - stage I; stage II - basal) with a coefficient of reproducibility (CR) of 22%, 21%; and 25%, respectively. Changes in NT-proBNP urinary levels had a CR of 7.1%, 6.8% and 9.4%. Finally, we found a good correlation between plasma and urinary levels (p<0.0001) and between the different NT-proBNP plasma (p<0.0001) and urine measurements (p<0.0001).

Conclusions: NT-proBNP plasma and urine levels show good stability in a 24-month follow-up of stable heart failure patients. As a result, assessment of urinary and plasma NT-proBNP concentrations may be a meaningful tool to monitor the follow-up of patients with heart failure. The results suggest that variations in peptide concentrations exceeding 22% in plasma and 7% in urine in a 12-month follow-up and 25% and 9% in a 24-month follow-up may be pathophysiological relevant.