title: Myeloperoxidase in the diagnosis of acute coronary syndromes: the importance of spectrum.
abstract: BACKGROUND
  Myeloperoxidase (MPO) is proposed for risk stratification in patients with suspected acute coronary syndromes (ACSs). We determined if MPO has diagnostic value in patients being evaluated for ACS.
  
  
  METHODS
  MIDAS was an 18-center prospective study enrolling suspected ACS emergency department patients who presented <8 hours after symptom onset and in whom serial cardiac markers and objective cardiac perfusion testing were planned. Blinded MPO (Biosite, Inc, San Diego, CA) and troponin I (Triage Cardio 3; Biosite, Inc) were drawn at arrival, and Troponin I (TnI) was measured at 90, 180, and 360 minutes. Final diagnoses were adjudicated by the local investigator blinded to study assay.
  
  
  RESULTS
  Of 1,018 patients, 54% were male, 26% black, with a mean age of 58 ± 13 years. Diagnoses were ACS in 288 (23%) and noncardiac chest pain (NCCP) in 788 (77%). Of patients with ACS, 94 (9.2%) had a myocardial infarction (MI) at presentation (69 non-ST-elevation MI, 25 ST-elevation MI), and 136 had unstable angina. Using a cutpoint of 210 ng/mL to provide 90% specificity, MPO had a sensitivity of 0.18; negative predictive value, 0.69; positive predictive value, 0.47; negative likelihood ratio, 0.91; and a positive likelihood ratio of 1.83 to differentiate ACS and NCCP. Because of the large overlap of quartiles, MPO was not clinically useful to predict serial TnI changes. The C statistics ± 95% CI for MPO differentiating ACS from NCCP and for AMI versus NCCP were 0.629 ± 0.04 and 0.666 ± 0.06, respectively.
  
  
  CONCLUSIONS
  Myeloperoxidase has insufficient accuracy for decision making in patients with suspected ACS.
authors.affiliation: Cleveland Clinic Foundation, OH, USA. meltonc@ccf.org
authors.forename: W Frank
authors.initials: WF
authors.lastname: Peacock
authors.forename: John
authors.initials: J
authors.lastname: Nagurney
authors.forename: Robert
authors.initials: R
authors.lastname: Birkhahn
authors.forename: Adam
authors.initials: A
authors.lastname: Singer
authors.forename: Nathan
authors.initials: N
authors.lastname: Shapiro
authors.forename: Judd
authors.initials: J
authors.lastname: Hollander
authors.forename: Ted
authors.initials: T
authors.lastname: Glynn
authors.forename: Richard
authors.initials: R
authors.lastname: Nowak
authors.forename: Basmah
authors.initials: B
authors.lastname: Safdar
authors.forename: Chadwick
authors.initials: C
authors.lastname: Miller
authors.forename: Mary
authors.initials: M
authors.lastname: Peberdy
authors.forename: Francis
authors.initials: F
authors.lastname: Counselman
authors.forename: Abhinav
authors.initials: A
authors.lastname: Chandra
authors.forename: Joshua
authors.initials: J
authors.lastname: Kosowsky
authors.forename: James
authors.initials: J
authors.lastname: Neuenschwander
authors.forename: Jon
authors.initials: J
authors.lastname: Schrock
authors.forename: Stephen
authors.initials: S
authors.lastname: Plantholt
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Lewandrowski
authors.forename: Vance
authors.initials: V
authors.lastname: Wong
authors.forename: Ken
authors.initials: K
authors.lastname: Kupfer
authors.forename: Deborah
authors.initials: D
authors.lastname: Diercks
mesh_terms: D054058:Acute Coronary Syndrome / Q000150:complications / Q000175:diagnosis* / Q000201:enzymology; D000368:Aged; D000787:Angina Pectoris / Q000209:etiology; D003935:Diagnostic Techniques, Cardiovascular / Q000592:standards*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009195:Peroxidase / Q000097:blood*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012306:Risk; D012680:Sensitivity and Specificity; D019210:Troponin I / Q000097:blood; D014481:United States
chemical_list: D019210:Troponin I; D009195:Peroxidase