title: Coronary calcium progression rates with a zero initial score by electron beam tomography.
abstract: BACKGROUND
  A review of existing literature shows that for individuals with initial coronary calcium scores (CCS) of zero it would be reasonable to consider follow-up scanning no sooner than 3 years from the initial evaluation, however the data is very limited. In this study, we sought to determine the rate of new calcifications in patients initially presenting with a zero initial score on electron beam tomography (EBT).
  
  
  RESULTS
  We evaluated 710 physician-referred participants (253 women and 448 men, mean age=56+/-9 years [range=29 to 93]) with no coronary artery calcium (CAC) at baseline electron beam tomography (EBT) scan. The participants underwent a follow-up scan at least 12 months apart. In our study, 248 (35%) were followed for 1-3 years, 256 (36%) for 3-5 years and 204 (29%) for >5 years, respectively. Overall, more than half of the individuals (62%) did not develop any CAC (score remained zero) in the interim period, whereas only 2% had CAC progression >50 during the follow-up. The overall median (interquartile range) and mean+/-S.D. change/year in these individuals was 0 (0-0.8) and 1+/-3, respectively. Only 11 (2%) had CAC progression/year of 11-50, whereas 3 (1%) had CAC change/year >50. It is interesting to note that even among individuals with long-term follow-up (>5 years), very few individuals (2%) had CAC progression >50. Individuals with follow-up 3-5 years did not have a significantly higher odds ratio for CAC change >10 (p=0.17) as compared to the reference group (follow-up of 1-3 years). All the other individuals who had a longer follow-up (>5 years) had a significantly higher likelihood of CAC progression >10 (OR=6.6, 95% CI=2.6-16.9, p<0.0001) compared to the reference group.
  
  
  CONCLUSIONS
  In individuals with no detectable coronary calcium on an initial EBT scan, a repeat scan can be recommended no sooner than 5 years.
authors.affiliation: Division of Cardiology, Los Angeles Biomedical Research Center at Harbor-UCLA, Torrance, CA, USA.
authors.forename: Ambarish
authors.initials: A
authors.lastname: Gopal
authors.forename: Khurram
authors.initials: K
authors.lastname: Nasir
authors.forename: Sandy T
authors.initials: ST
authors.lastname: Liu
authors.forename: Ferdinand R
authors.initials: FR
authors.lastname: Flores
authors.forename: Lynn
authors.initials: L
authors.lastname: Chen
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Budoff
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D002118:Calcium / Q000378:metabolism; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D003331:Coronary Vessels / Q000378:metabolism / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012307:Risk Factors; D014057:Tomography, X-Ray Computed
chemical_list: D002118:Calcium