title: Coronary calcium screening in asymptomatic patients as a guide to risk factor modification and stress myocardial perfusion imaging.
abstract: BACKGROUND
  Previous studies have demonstrated a correlation between the extent of coronary artery calcification (CAC) and atherosclerotic plaque. As a result, CAC screening could be useful in predicting cardiovascular risk in individuals in whom atherosclerosis is developing. One possible method of detecting and quantifying CAC is by x-ray computed tomography, which potentially allows one to stratify patients into groups requiring risk factor modification or follow-up testing such as myocardial perfusion single photon emission computed tomography (SPECT).
  
  
  RESULTS
  This study was designed to evaluate the clinical utility of multidetector computed tomography (MDCT) in a cardiology practice setting. A retrospective analysis was performed on data from 794 asymptomatic patients who underwent CAC screening over an 8-month period. On the basis of the CAC score and physician consultation, 102 patients underwent subsequent myocardial perfusion SPECT imaging. A substudy was also conducted in 306 patients to measure the interscan variability of MDCT across different CAC score ranges. CAC was detected in 422 of 794 patients. Of these, the CAC was moderate (Agatston score = 101-400) in 14% and severe (>400) in 9%. Patients with 3 or more cardiac risk factors were most likely to exhibit moderate to severe CAC. In myocardial perfusion SPECT testing, no patient with an Agatston score lower than 100 had an abnormal study. In contrast, 41% of patients with severe CAC had an abnormal SPECT study. In the reproducibility substudy the minimal CAC group had the largest variability (86.0%) whereas the severe CAC group had the lowest variability (9.5%).
  
  
  CONCLUSIONS
  CAC screening with MDCT is justified for asymptomatic patients with 3 or more cardiac risk factors. However, risk factor assessment is poor at predicting which individuals will have CAC if fewer risk factors are present. In terms of the interscan variability, MDCT is capable of following changes in CAC for patients with Agatston scores greater than 100. Finally, this study demonstrated that an Agatston score of 400 is a logical threshold to initiate follow-up myocardial perfusion SPECT testing.
authors.affiliation: Cardiovascular Consultants, Mid America Heart Institute, Saint Luke's Hospital, Kansas City, MO 64111, USA.
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Moser
authors.forename: James H
authors.initials: JH
authors.lastname: O'Keefe
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Bateman
authors.forename: Iain A
authors.initials: IA
authors.lastname: McGhie
mesh_terms: D000241:Adenosine; D000367:Age Factors; D002114:Calcinosis / Q000150:complications / Q000000981:diagnostic imaging*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000209:etiology; D048909:Diabetes Complications; D004198:Disease Susceptibility / Q000000981:diagnostic imaging; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011859:Radiography; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D013223:Statistics as Topic
chemical_list: D000241:Adenosine