title: Is plasma N-BNP a good indicator of the functional reserve of failing hearts? The FRESH-BNP study.
abstract: OBJECTIVE
  Whether plasma N-terminal brain natriuretic peptide (N-BNP) is useful in the diagnosis of heart failure (HF) depends traditionally on whether it is as good as the putative 'gold-standard', left ventricular ejection fraction (LVEF), in indicating cardiac dysfunction. However, since HF is primarily an impairment of function of the cardiac pump, we explored the relationship between N-BNP and direct and indirect indicators of cardiac pump dysfunction.
  
  
  RESULTS
  Eighty-six HF patients (mean age 56 years) with a range of LVEF's (mean 36.9+/-15.2%, range 15-66%) and 10 age-matched healthy controls were recruited into the study and had resting N-BNP measured. Cardiopulmonary exercise testing was performed to assess peak oxygen consumption (Vo(2)). A subgroup of 23 subjects underwent further exercise haemodynamic assessment to evaluate peak cardiac power output (CPO). The CHF group had significantly higher N-BNP (median [interquartile range]) levels (299 [705] fmol/ml) than the control group (7 [51] fmol/ml, P<0.005). Significant correlations between N-BNP and peak Vo(2), and N-BNP and peak CPO were observed (R> or =0.5, P<0.005). Although significant correlation was observed between N-BNP and LVEF (R=0.34, P=0.01), the correlations between LVEF and peak Vo(2) or peak CPO (all R<0.3, P>0.3) were not significant. Multivariate analysis identified plasma N-BNP and NYHA class, but not LVEF, as independent predictors of peak Vo(2).
  
  
  CONCLUSIONS
  We have found that N-BNP was surprisingly good as a simple indicator of cardiac pump dysfunction. Since heart failure is an inadequacy of function, these results strongly support the notion that N-BNP is a useful blood test in estimating the extent of cardiac pump dysfunction and helpful in establishing positive diagnosis of heart failure.
authors.affiliation: Academic Unit of Molecular Vascular Medicine, University of Leeds, Martin Wing, Leeds General Infirmary, Leeds LS1 3EX, UK.
authors.forename: Simon G
authors.initials: SG
authors.lastname: Williams
authors.forename: Leong L
authors.initials: LL
authors.lastname: Ng
authors.forename: Russell J
authors.initials: RJ
authors.lastname: O'Brien
authors.forename: Steve
authors.initials: S
authors.lastname: Taylor
authors.forename: D Jay
authors.initials: DJ
authors.lastname: Wright
authors.forename: Lip-Bun
authors.initials: LB
authors.lastname: Tan
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002908:Chronic Disease; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010101:Oxygen Consumption; D010446:Peptide Fragments / Q000097:blood*; D012107:Research Design; D012720:Severity of Illness Index; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000097:blood / Q000503:physiopathology; D016277:Ventricular Function, Left
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain