title: Comparison of the atherosclerotic burden among asymptomatic patients vs matched volunteers.
abstract: BACKGROUND
  While asymptomatic patients should have a lower risk of cardiac events compared to symptomatic patients referred for cardiac stress testing, comparable event rates have been noted in some prior prognostic studies. To test if a high burden of undetected atherosclerosis among asymptomatic patients helps explain such findings, we compared atherosclerotic burden, as measured by coronary artery calcium (CAC) scanning, in propensity-matched groups of volunteers and asymptomatic patients.
  
  
  METHODS
  CAC scans were performed on a research basis in 136 asymptomatic patients referred for exercise myocardial perfusion SPECT and in 1,398 volunteers. We performed matching by propensity scores to compare volunteers with the same CAD risk factor profile as our asymptomatic patients.
  
  
  RESULTS
  Among our matched groups, asymptomatic patients had significantly greater mean CAC scores than volunteers (394 ± 805 vs 151 ± 349, P = .001), primarily due to a higher frequency of CAC scores >1,000 (15.4% vs 2.5%, P < .001). Inducible myocardial ischemia by SPECT was present in 7% of patients, but was selectively concentrated among those with CAC scores >1,000, occurring in 27.0% of such patients vs only 1.9% among patients with CAC scores <1,000 (P < .0001).
  
  
  CONCLUSIONS
  In contrast to asymptomatic volunteers, asymptomatic patients referred for cardiac stress testing possess more extensive atherosclerosis as measured by CAC. Among asymptomatic patients with high CAC scores, the frequency of concomitant inducible myocardial ischemia is high. These results help explain prior prognostic studies concerning asymptomatic patients and indicate the importance of making a clinical distinction between healthy subjects and asymptomatic patients with respect to atherosclerotic risk.
authors.affiliation: Division of Cardiology, St. Lukes Roosevelt Hospital, 1111 Amsterdam Avenue, New York, NY, 10025, USA.
authors.forename: Alan
authors.initials: A
authors.lastname: Rozanski
authors.forename: Heidi
authors.initials: H
authors.lastname: Gransar
authors.forename: Leslee
authors.initials: L
authors.lastname: Shaw
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Wong
authors.forename: James
authors.initials: J
authors.lastname: Min
authors.forename: Romalisa
authors.initials: R
authors.lastname: Miranda-Peats
authors.forename: Sean W
authors.initials: SW
authors.lastname: Hayes
authors.forename: John D
authors.initials: JD
authors.lastname: Friedman
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
mesh_terms: D000368:Aged; D002118:Calcium / Q000032:analysis; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000453:epidemiology*; D003331:Coronary Vessels / Q000737:chemistry; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D002118:Calcium