Background: Little is known about the relationship of body fluid status with the levels and fluctuations of B-type natriuretic peptide (BNP) over the long-term.
Hypothesis: If BNP is to become useful for monitoring of patients with chronic heart failure (HF), the levels should reliably reflect both decompensation and improvement in the patient's condition.
Methods: Forty-six patients with chronic HF who were stable at study entry but had previous decompensation were recruited and followed up between June 2003 and September 2005. At each visit, they were examined for BNP level and HF-related signs of body fluid retention based on physical evaluation and pleural ultrasonography.
Results: During the study period, 26 patients developed decompensation and 20 maintained a stable clinical course. In the 26 decompensated patients, BNP levels fluctuated widely (110 +/- 73.7 pg/ml; range 25-290 pg/ml) even during stable periods. In all but three patients in this group, the maximum BNP level during decompensation was higher than that reached during stable periods. The BNP levels also fluctuated widely (180 +/- 123 pg/ml; range 16-489 pg/ml) in the 20 stable patients with HF. In all but one patient in this group, the BNP level was lower than the maximum BNP level obtained during the previous decompensation.
Conclusions: In patients with chronic HF with previous decompensation, there was a strong link between the appearance of clinical HF sign(s) of fluid retention and an increased BNP level despite wide intraindividual fluctuations in BNP over time. Thus, BNP levels reliably reflect both decompensation and improvement.