title: Comparison of myocardial perfusion imaging and cardiac troponin I in patients admitted to the emergency department with chest pain.
abstract: BACKGROUND
  Identification of patients with acute coronary syndromes (ACS) among those who present to emergency departments with possible myocardial ischemia is difficult. Myocardial perfusion imaging with 99mTc sestamibi and measurement of serum cardiac troponin I (cTnI) both can identify patients with ACS.
  
  
  RESULTS
  Patients considered at low to moderate risk for ACS underwent gated single-photon emission CT sestamibi imaging and serial myocardial marker measurements of creatine kinase-MB, total creatine kinase activity, and cTnI over 8 hours. Positive perfusion imaging was defined as a perfusion defect with associated abnormalities in wall motion or thickening. cTnI >/=2.0 ng/mL was considered abnormal. Among the 620 patients studied, 59 (9%) had myocardial infarction and 81 (13%) had significant coronary disease; of these patients, 58 underwent revascularization. Perfusion imaging was positive in 241 patients (39%), initial cTnI was positive in 37 (6%), and cTnI was >/=2.0 ng/mL in 74 (12%). Sensitivity for detecting myocardial infarction was not significantly different between perfusion imaging (92%) and cTnI (90%), and both were significantly higher than the initial cTnI (39%). Sensitivity for predicting revascularization or significant coronary disease was significantly higher for perfusion imaging than for serial cTnI, although specificity for all end points was significantly lower. Lowering the cutoff value of cTnI to 1.0 ng/mL did not significantly change the results.
  
  
  CONCLUSIONS
  Early perfusion imaging and serial cTnI have comparable sensitivities for identifying myocardial infarction. Perfusion imaging identified more patients who underwent revascularization or who had significant coronary disease, but it had lower specificity. The 2 tests can provide complementary information for identifying patients at risk for ACS.
authors.affiliation: Department of Internal Medicine, Division of Cardiology, Medical College of Virginia Campus of Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Kontos
authors.forename: R L
authors.initials: RL
authors.lastname: Jesse
authors.forename: F P
authors.initials: FP
authors.lastname: Anderson
authors.forename: K L
authors.initials: KL
authors.lastname: Schmidt
authors.forename: J P
authors.initials: JP
authors.lastname: Ornato
authors.forename: J L
authors.initials: JL
authors.lastname: Tatum
mesh_terms: D015415:Biomarkers / Q000097:blood; D002637:Chest Pain / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003327:Coronary Disease / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D017202:Myocardial Ischemia / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D019210:Troponin I / Q000097:blood*
chemical_list: D015415:Biomarkers; D019275:Radiopharmaceuticals; D019210:Troponin I; D017256:Technetium Tc 99m Sestamibi