title: Long-term prognostic value of coronary calcification detected by electron-beam computed tomography in patients undergoing coronary angiography.
abstract: BACKGROUND
  Electron-beam CT (EBCT) quantification of coronary artery calcification (CAC) allows noninvasive assessment of coronary atherosclerosis. We undertook a follow-up study to determine whether CAC extent, measured at the time of angiography by EBCT, predicted future hard cardiac events, comprising cardiac death and nonfatal myocardial infarction (MI). We also assessed the potential of selected coronary artery disease (CAD) risk factors, prior CAD event history (MI or revascularization), and angiographic findings (number of diseased vessels and overall disease burden) to predict subsequent hard events.
  
  
  RESULTS
  Two hundred eighty-eight patients who underwent contemporaneous coronary angiography and EBCT scanning were contacted after a mean of 6.9 years. Vital status and history of MI during follow-up were determined. Cox proportional hazards models were used to compare the predictive ability of CAC extent with selected CAD risk factors, CAD event history, and angiographic findings. Median CAC score was 160 (range 0 to 7633). The 22 patients who experienced hard events during follow-up were older and had more extensive CAC and angiographic disease (P<0.05). Only 1 of 87 patients with CAC score <20 experienced a subsequent hard event during follow-up. Event-free survival was significantly higher for patients with CAC scores <100 than for those with scores >/=100 (relative risk 3.20; 95% CI 1.17 to 8.71). When a stepwise multivariable model was used, only age and CAC extent predicted hard events (risk ratios 1.72 and 1.88, respectively; P<0.05).
  
  
  CONCLUSIONS
  In patients undergoing angiography, CAC extent on EBCT is highly predictive of future hard cardiac events and adds valuable prognostic information.
authors.affiliation: Division of Cardiovascular Diseases, Diagnostic Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: P C
authors.initials: PC
authors.lastname: Keelan
authors.forename: L F
authors.initials: LF
authors.lastname: Bielak
authors.forename: K
authors.initials: K
authors.lastname: Ashai
authors.forename: L S
authors.initials: LS
authors.lastname: Jamjoum
authors.forename: A E
authors.initials: AE
authors.lastname: Denktas
authors.forename: J A
authors.initials: JA
authors.lastname: Rumberger
authors.forename: P F
authors.initials: PF
authors.lastname: Sheedy II
authors.forename: P A
authors.initials: PA
authors.lastname: Peyser
authors.forename: R S
authors.initials: RS
authors.lastname: Schwartz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging*; D017023:Coronary Angiography; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*