title: Troponin T levels and infarct size by SPECT myocardial perfusion imaging.
abstract: OBJECTIVE
  To evaluate the relationship between serial cardiac troponin T (cTnT) levels with infarct size and left ventricular ejection fraction by gated single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) in patients with acute myocardial infarction (AMI).
  
  
  BACKGROUND
  Current guidelines recommend the use of cTnT as the biomarker of choice for the diagnosis of AMI. Data relating cTnT to SPECT-MPI in patients with AMI are limited.
  
  
  METHODS
  A subset of patients with their first AMI participating in a community-based cohort of AMI in Olmsted County, Minnesota, were prospectively studied. Serial cTnT levels were evaluated at presentation, <12 h and 1, 2, and 3 days after onset of pain. Peak cTnT was defined as the maximum cTnT value.
  
  
  RESULTS
  A total of 121 patients (age, 61 ± 13 years; 31% women) with AMI underwent gated SPECT-MPI at a median (25th percentile, 75th percentile) of 10 (5, 15) days post-AMI. The type of infarct was non-ST-segment elevation myocardial infarction in 61%, and 13% were anterior in location. The median infarct size was 1% (0%, 11%) and the median gated left ventricular ejection fraction was 54% (47%, 60%). Fifty-nine patients (49% of the population) had no measurable infarction by SPECT-MPI. Independent predictors of measurable SPECT-MPI infarct size included cTnT at days 1, 2, and 3 and peak cTnT, but not at presentation or <12 h. In receiver-operator characteristic analysis, the area under the curve was highest at day 3. Receiver-operator characteristic analysis demonstrated a cutoff of 1.5 ng/ml for peak cTnT for the detection of measurable infarct size.
  
  
  CONCLUSIONS
  In a community-based cohort of patients with their first AMI, independent predictors of measurable SPECT-MPI infarct size included cTnT at days 1, 2, and 3 and peak cTnT. In contrast, cTnT level at presentation and <12 h was not an independent predictor of myocardial infarction size as assessed by SPECT-MPI. Receiver-operator characteristic analysis demonstrated a cutoff value peak cTnT of 1.5 ng/ml for the detection of measurable infarct.
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA. miller.todd@mayo.edu
authors.forename: Adelaide M
authors.initials: AM
authors.lastname: Arruda-Olson
authors.forename: Véronique L
authors.initials: VL
authors.lastname: Roger
authors.forename: Allan S
authors.initials: AS
authors.lastname: Jaffe
authors.forename: David O
authors.initials: DO
authors.lastname: Hodge
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Gibbons
authors.forename: Todd D
authors.initials: TD
authors.lastname: Miller
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D017023:Coronary Angiography; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008910:Minnesota; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D009206:Myocardium / Q000473:pathology*; D016017:Odds Ratio; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012372:ROC Curve; D013318:Stroke Volume; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D020107:Troponin T / Q000097:blood*; D016277:Ventricular Function, Left
chemical_list: D015415:Biomarkers; C545568:TNNT2 protein, human; D020107:Troponin T