title: Severity of coronary artery calcification by electron beam computed tomography predicts silent myocardial ischemia.
abstract: BACKGROUND
  Detection of subclinical coronary artery disease (CAD) before the development of life-threatening cardiac complications has great potential clinical relevance. Electron beam computed tomography (EBCT) is currently the only noninvasive test that can detect CAD in all stages of its development and thus has the potential to be an excellent screening technique for identifying asymptomatic subjects with underlying myocardial ischemia.
  
  
  RESULTS
  Over 2.5 years, we prospectively studied 3895 generally asymptomatic subjects with EBCT, 411 of whom had stress myocardial perfusion tomography (SPECT) within a close (median, 17 days) time period. SPECT and exercise treadmill results were compared with the coronary artery calcium score (CACS) as assessed by EBCT. The total CACS identified a population at high risk for having myocardial ischemia by SPECT although only a minority of subjects (22%) with an abnormal EBCT had an abnormal SPECT. No subject with CACS <10 had an abnormal SPECT compared with 2.6% of those with scores from 11 to 100, 11.3% of those with scores from 101 to 399, and 46% of those with scores >/=400 (P<0.0001). CACS predicted an abnormal SPECT regardless of subject age or sex.
  
  
  CONCLUSIONS
  CACS identifies a high-risk group of asymptomatic subjects who have clinically important silent myocardial ischemia. Our results support the role of EBCT as the initial screening tool for identifying individuals at various stages of CAD development for whom therapeutic decision making may differ considerably.
authors.affiliation: Cardiovascular Institute and Fu Wai Hospital, Peking Union Medical College, Beijing, China.
authors.forename: Z X
authors.initials: ZX
authors.lastname: He
authors.forename: T D
authors.initials: TD
authors.lastname: Hedrick
authors.forename: C M
authors.initials: CM
authors.lastname: Pratt
authors.forename: M S
authors.initials: MS
authors.lastname: Verani
authors.forename: V
authors.initials: V
authors.lastname: Aquino
authors.forename: R
authors.initials: R
authors.lastname: Roberts
authors.forename: J J
authors.initials: JJ
authors.lastname: Mahmarian
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000175:diagnosis*; D003327:Coronary Disease / Q000175:diagnosis*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D014054:Tomography; D015899:Tomography, Emission-Computed, Single-Photon