Effect of compensated renal dysfunction on approved heart failure markers -: Direct comparison of brain natriuretic peptide (BNP) and N-terminal Pro-BNP

Brain natriuretic peptide ( BNP) and N-terminal pro-BNP ( NT-proBNP) are markers of heart failure. Although renal dysfunction may increase plasma concentrations, the magnitude of this effect has not been assessed in a head-to-head comparison between the clinically approved tests. We assessed the effect of compensated renal dysfunction on BNP ( Triage BNP; Biosite) and NT-proBNP ( elecsys proBNP; Roche) in 469 randomly selected stable outpatients after myocardial infarction ( MI; Monitoring Trends and Determinants in Cardiovascular Diseases [ MONICA] register Augsburg) who were characterized with respect to renal function ( glomerular filtration rate [ GFR]; Cockroft method) and left ventricular ( LV) ejection fraction ( EF) and mass ( 2D echocardiography). BNP and NT-proBNP were elevated in MI patients with LV dysfunction ( LVD; EF <35%) compared with MI patients with preserved EF ( >45%; BNP 139 +/- 27 pg/mL versus 75 +/- 6; NT-proBNP 816 +/- 237 pg/mL versus 243 +/- 20; both P < 0.03). Among all MI patients, the prevalence of renal dysfunction ( GFR <85 mL/min) was 24%. BNP and NT-proBNP were significantly elevated in MI patients with renal dysfunction ( BNP 132 +/- 17 pg/mL versus 68 +/- 4 without renal dysfunction; NT-proBNP 535 +/- 80 pg/mL versus 232 +/- 19; both P < 0.05), and both markers were correlated with GFR in univariate and multivariate analyses ( all P < 0.01). When binary cut-off values were stratified according to the absence or presence of renal dysfunction ( BNP 75 pg/mL and 125 pg/mL, respectively; NT-proBNP 100 pg/mL and 350pg/mL, respectively), the predictive power of both markers for the detection of LVD increased substantially. BNP and NT-proBNP are almost similarly influenced by mild-to-moderate renal dysfunction. Renal dysfunction is a potential cause of elevated marker concentrations in the absence of LVD, and cut-off concentrations should be stratified according to renal function.