Biological Variation of Brain Natriuretic Peptide and Cardiac Events in Stable Outpatients With Nonischemic Chronic Heart Failure

BACKGROUND: To evaluate the biological variation and prognostic value of brain natriuretic peptide (BNP) for stable outpatients with nonischemic chronic heart failure (NICHF). METHODS AND RESULTS: Biological variation in BNP was evaluated using an automated assay system in 140 outpatients with NICHF. The stable clinical condition during the 2-month study period was defined as unchanged NYHA and unchanged left ventricular ejection fraction; therefore, 7 patients were excluded during the 2 months. Thereafter, 133 patients were prospectively followed and the relationship between cardiac events and the plasma BNP concentrations (at baseline and after 2 months) were evaluated as well as the changes in BNP. The biological variation in BNP (2-month interval) was calculated as 22.3%. During a mean follow-up period of 42 months, 26 patients had cardiac events. According to stepwise multivariate analyses, plasma BNP after 2 months (P=0.0002) and % change in BNP (P=0.0067) were significant independent predictors of cardiac events. CONCLUSIONS: These findings indicated that a combination of the absolute value of BNP after 2 months and % increase in BNP (2-month interval) is useful for predicting cardiac events in stable outpatients with NICHF.