Cardiorenal Function in Heart Failure
What are the changes in kidney function in combination with dynamic changes in N-terminal pro–B-type natriuretic peptide (NT-proBNP) when hospitalized for acute decompensated heart failure (ADHF)?
The study authors conducted an individual patient data analysis from six prospective cohorts consisting of 1,232 patients hospitalized for ADHF who satisfied the following inclusion criteria: 1) admitted because of clinically validated ADHF, 2) discharged alive, 3) serum creatinine level, and 4) NT-proBNP measurements were available at admission and at discharge. Endpoints were all-cause mortality and the composite of all-cause mortality and/or readmission for a cardiovascular reason within 180 days after discharge. They defined severe worsening of renal function (sWRF) as an increase in creatinine of >0.5 mg/dl in combination with >25% increase in serum creatinine level between admission and discharge.
The study authors found that the occurrence of sWRF did not differ between patients with a low and those with a high percentage drop in NT-proBNP, suggesting that severe WRF is not related to the amount of decrease of NT-proBNP. A decrease of more than 30% in NT-proBNP was associated with a 15% absolute lower mortality (all-cause mortality hazard ratio [HR], 1.81; 95% confidence interval [CI], 1.32-2.50) and a reduction in the composite endpoint (HR, 1.36; 95% CI, 1.13-1.64), regardless of changes in renal function and other clinical variables.
The authors concluded that WRF is a measure of prognosis, but is of lesser value than, and independent of, the prognostic changes induced by adequate NT-proBNP reduction. This suggests that in ADHF patients, it may be warranted to strive for an optimal decrease in NT-proBNP, even if this induces WRF.
The pathophysiology of cardiorenal function in heart failure is complex because the responses to therapy are not predictable because of varying degrees of cardiac and renal malfunction prompting experts to expound a multidisciplinary approach. This is an important study because it suggests that NT-proBNP is a better biomarker than worsening renal function. Further data are now needed to determine whether indeed BNP is a better predictor when the patients are further segmented into the different types of cardiorenal failure (J Am Coll Cardiol 2008;52:1527-39).
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