title: Stress myocardial perfusion single-photon emission computed tomography is clinically effective and cost effective in risk stratification of patients with a high likelihood of coronary artery disease (CAD) but no known CAD.
abstract: OBJECTIVE
  We sought to evaluate the prognostic and cost implications of stress myocardial perfusion single-photon emission computed tomography (SPECT), or MPS, in patients with a high pretest likelihood (>0.85) of coronary artery disease (CAD) with no previous CAD.
  
  
  BACKGROUND
  Sparse data are available regarding the prognostic performance characteristics of MPS in this patient group.
  
  
  METHODS
  We followed up 1,270 consecutive patients with no previous revascularization or myocardial infarction (MI), with a pre-exercise tolerance test (ETT) likelihood of CAD > or =0.85, who underwent exercise or adenosine stress MPS (follow-up 94.4% complete; 2.2 +/- 1.2 years; 60 hard events [5.9%, 2.6%/year]). Risk adjustment of survival data was done using Cox proportional hazards analysis. Costs per reclassification of risk were calculated using assumed costs and threshold analyses.
  
  
  RESULTS
  In patients treated medically after MPS, normal MPS had a low risk of cardiac death and hard events (0.6% and 1.3% per year, respectively). With increasing extent and severity of MPS defects, the risk of both cardiac death and hard events increased significantly (p < 0.05). Cox models indicated that the addition of MPS data resulted in incremental prognostic value over pre-MPS data (chi-square increase 48 to 87, p < 0.0001). Compared with strategies of initial referral to ETT in patients able to exercise, initial referral to MPS appeared to be a more cost-effective strategy. Similarly, compared with a strategy of direct referral to catheterization in patients with a high likelihood of CAD, initial referral to MPS is a cost-saving approach.
  
  
  CONCLUSIONS
  In patients with a high likelihood of CAD but without known CAD, stress MPS yields incremental value and achieves risk stratification in a cost-effective manner. The current results support a strategy of initial stress imaging in this patient cohort, as a reasonable alternative to direct referral to catheterization or initial ETT.
authors.affiliation: Cardiovascular Division, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California 90048, USA.
authors.forename: Rory
authors.initials: R
authors.lastname: Hachamovitch
authors.forename: Sean W
authors.initials: SW
authors.lastname: Hayes
authors.forename: John D
authors.initials: JD
authors.lastname: Friedman
authors.forename: Ishac
authors.initials: I
authors.lastname: Cohen
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000000981:diagnostic imaging*; D003362:Cost-Benefit Analysis; D005080:Exercise Test / Q000191:economics; D005260:Female; D006334:Heart Function Tests / Q000191:economics* / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D018570:Risk Assessment; D015899:Tomography, Emission-Computed, Single-Photon / Q000191:economics*; D016896:Treatment Outcome