Change in the NT‐proBNP/Mature BNP Molar Ratio Precedes Worsening Renal Function in Patients With Acute Heart Failure: A Novel Predictor Candidate for Cardiorenal Syndrome

Abstract

Background Early detection for worsening renal function ( WRF ) is indispensable in patients with acute decompensated heart failure (HF). We tested the hypothesis that the difference in the circulating levels of each B‐type or brain natriuretic peptide ( BNP ) molecular form is associated with the occurrence of WRF . Methods and Results Circulating levels of pro BNP , the NT‐proBNP (N‐terminal pro BNP ), and total BNP (pro BNP +mature BNP ) were prospectively measured in patients with acute decompensated HF using specific and sensitive enzyme immunochemiluminescent assays. An estimated mature BNP (em BNP ) concentration was calculated by subtracting pro BNP levels from total BNP levels. WRF was defined as a >20% decrease in the estimated glomerular filtration rate during the hospitalization. One‐way repeated‐measures ANOVA was used to compare the changes of variables between the patients with and without WRF . In patients with acute decompensated HF (New York Heart Association class III – IV ; 96%) hospitalized for HF , NT ‐pro BNP levels did not differ during the hospitalization between patients with and without WRF (n=42 and 140, respectively). By contrast, em BNP levels were lower in patients with WRF than in those without WRF on day 3 after admission. NT ‐pro BNP /em BNP molar ratios were elevated on day 3 after admission in the patients with WRF , before estimated glomerular filtration rate declined, but were unchanged in patients without WRF . On day 3 after hospital admission, NT ‐pro BNP /em BNP ratios were strongly associated with percentage decreases in estimated glomerular filtration rate. Conclusions These findings suggest that elevation of NT ‐pro BNP /em BNP ratio precedes WRF in patients with acute HF and can be a potentially useful biomarker for risk stratification of cardiorenal syndrome.