title: Low high-sensitivity troponin I and zero coronary artery calcium score identifies coronary CT angiography candidates in whom further testing could be avoided.
abstract: OBJECTIVE
  Pilot study to determine whether among subjects receiving coronary computed tomography angiography (CTA), the combination of high-sensitivity troponin I (hsTnI) and coronary artery calcium score (CACS) identifies a low-risk population in whom CTA might be avoided.
  
  
  METHODS
  A cross-sectional study of 314 symptomatic patients receiving CTA as part of their acute coronary syndrome evaluation was conducted. hsTnI was measured with Abbott Laboratories' hsTnI assay. CACSs were calculated via the Agatston method. Patients were followed for at least 30 days after discharge for the occurrence of major adverse cardiac events (MACEs; all-cause mortality, acute coronary syndrome, and revascularization).
  
  
  RESULTS
  Of 314 subjects studied, 213 (67.8%) had no coronary artery stenosis, and 67 (21.3%), 28 (8.9%), and 6 (1.9%) had maximal coronary artery stenosis of 1%-49%, 50%-69%, and 70% or greater, respectively. All MACEs occurred during index hospitalization and include one myocardial infarction and four revascularizations. Sixty-two percent (189/307) of subjects had zero CACS, and 24% (76/314) of subjects had undetected hsTnI. No subjects with undetectable hsTnI or zero CACS had an MACE. A strategy of avoiding further testing in subjects with undetectable initial hsTnI, performing CACS on subjects with detectable initial hsTnI but nonincreased hsTnI (less than 99th percentile), and obtaining CTA in subjects with Agatston greater than 0 will have a negative predictive value of 100.0% (95% confidence interval, 98.2%-100.0%). This strategy will avoid CTA in 63% (198/314) of subjects.
  
  
  CONCLUSIONS
  In this pilot study, the addition of CACS to hsTnI improves the identification of low-risk subjects in whom CTA might be avoided.
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University School of Medicine, 5801 Smith Avenue, Baltimore, MD 21209. Electronic address: fkorley1@jhmi.edu.
authors.forename: Frederick K
authors.initials: FK
authors.lastname: Korley
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Richard T
authors.initials: RT
authors.lastname: George
authors.affiliation: Cardiovascular Division and Division of Core Clinical Laboratory Services, Departments of Medicine and Laboratory Medicine and Pathology, Mayo Clinic and Medical School, Rochester, Minnesota.
authors.forename: Allan S
authors.initials: AS
authors.lastname: Jaffe
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University School of Medicine, 5801 Smith Avenue, Baltimore, MD 21209.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Rothman
authors.affiliation: Division of Clinical Chemistry, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Lori J
authors.initials: LJ
authors.lastname: Sokoll
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University School of Medicine, 5801 Smith Avenue, Baltimore, MD 21209.
authors.forename: Christopher
authors.initials: C
authors.lastname: Fernandez
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University School of Medicine, 5801 Smith Avenue, Baltimore, MD 21209.
authors.forename: Hayley
authors.initials: H
authors.lastname: Falk
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Post
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University School of Medicine, 5801 Smith Avenue, Baltimore, MD 21209.
authors.forename: Mustapha O
authors.initials: MO
authors.lastname: Saheed
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Gary
authors.initials: G
authors.lastname: Gerstenblith
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Berkowitz
authors.affiliation: Department of Emergency Medicine, Johns Hopkins University School of Medicine, 5801 Smith Avenue, Baltimore, MD 21209.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Hill
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D015984:Causality; D015897:Comorbidity; D017023:Coronary Angiography / Q000706:statistics & numerical data*; D003324:Coronary Artery Disease / Q000097:blood / Q000175:diagnosis* / Q000401:mortality; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D000069342:Medical Overuse / Q000517:prevention & control* / Q000706:statistics & numerical data; D008875:Middle Aged; D010865:Pilot Projects; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D019210:Troponin I / Q000097:blood*; D061205:Vascular Calcification / Q000097:blood / Q000175:diagnosis* / Q000401:mortality
chemical_list: D015415:Biomarkers; D019210:Troponin I
keywords: Acute coronary syndrome; coronary artery calcium; coronary computed tomography angiography; emergency department; high sensitivity troponin; troponin