title: Diagnostic utility of a single-epitope sandwich B-type natriuretic peptide assay in stable coronary artery disease: data from the Akershus Cardiac Examination (ACE) 1 Study.
abstract: OBJECTIVE
  To assess the merit of a novel single-epitope sandwich (SES) assay specific to the stable part of BNP in patients with reversible myocardial ischemia as post-translational modifications of BNP may influence assay performance.
  
  
  METHODS
  We measured BNP concentration by a conventional assay and the SES-BNP assay in 198 patients referred for myocardial perfusion imaging (MPI). BNP concentration was determined before and immediately after exercise stress testing, and 1.5 and 4.5h later. Patients were categorized according to MPI results.
  
  
  RESULTS
  BNP concentration was higher with both assays at all time points in patients with reversible myocardial ischemia (n=19) compared to the other patients (n=179). Measuring BNP after stress testing or calculating the changes in BNP concentration did not improve diagnostic accuracy compared to baseline measurements: SES-BNP: AUC 0.71 (95% CI 0.58-0.84) vs. conventional BNP: 0.71 (0.59-0.83), p=0.96. By linear regression analysis, reversible myocardial ischemia was significantly associated with baseline SES-BNP concentration (p=0.043), but not with measurements by the conventional assay (p=0.089). In multivariate logistic regression models, only baseline measurement with the SES-BNP assay was significantly associated with reversible myocardial ischemia: odds ratio [logarithmical transformed BNP] 2.00 (95% CI 1.16-3.47), p=0.013. The SES-BNP assay, but not the conventional BNP assay, reclassified a significant proportion of the patients towards their correct category on top of the best clinical model of our data set: NRI=0.47, p=0.04.
  
  
  CONCLUSIONS
  The SES-BNP assay was significantly associated with reversible myocardial ischemia as assessed by several statistical indices, while a conventional BNP assay was not.
authors.affiliation: Division of Medicine, Akershus University Hospital, Lørenskog, Norway. helge.rosjo@medisin.uio.no
authors.forename: Helge
authors.initials: H
authors.lastname: Røsjø
authors.forename: Natalia N
authors.initials: NN
authors.lastname: Tamm
authors.forename: Gunnhild
authors.initials: G
authors.lastname: Kravdal
authors.forename: Karina R
authors.initials: KR
authors.lastname: Seferian
authors.forename: Arne Didrik
authors.initials: AD
authors.lastname: Høiseth
authors.forename: Ståle
authors.initials: S
authors.lastname: Nygård
authors.forename: Pirouz
authors.initials: P
authors.lastname: Badr
authors.forename: Ragnhild
authors.initials: R
authors.lastname: Røysland
authors.forename: Torbjørn
authors.initials: T
authors.lastname: Omland
mesh_terms: D000368:Aged; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood; D003324:Coronary Artery Disease / Q000097:blood / Q000175:diagnosis*; D000939:Epitopes / Q000097:blood / Q000276:immunology; D005080:Exercise Test; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017202:Myocardial Ischemia / Q000097:blood / Q000175:diagnosis*; D055414:Myocardial Perfusion Imaging; D020097:Natriuretic Peptide, Brain / Q000097:blood* / Q000276:immunology; D011446:Prospective Studies; D012372:ROC Curve
chemical_list: D015415:Biomarkers; D000939:Epitopes; D020097:Natriuretic Peptide, Brain