Relation of Coronary Calcium Score by Electron Beam Computed Tomography to Arteriographic Findings in Asymptomatic and Symptomatic Adults

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Abstract

Coronary arteriography was performed on 18 asymptomatic, apparently healthy adults with elevated coronary calcium scores. To extend the range of observation to subjects with low calcium scores, arteriograms from 18 patients with exertional dyspnea and/or valvular heart disease and low calcium scores were also analyzed; these 18 patients were considered asymptomatic from the point of view of coronary artery disease (CAD). For the comparison of symptomatic and asymptomatic persons, 3 age and sex-matched symptomatic patients were also selected for each of the original 18 asymptomatic subjects. Arteriograms were analyzed by computer-assisted quantitative coronary arteriography at a remote site without knowledge of the calcium score or any other patient characteristics. In the 18 asymptomatic subjects with elevated calcium scores, the mean calcium score was 573 ± 504 (Agatston method) and the mean worst stenosis was 45% ± 16%. For all 36 patients without symptoms of CAD, worst stenosis was closely correlated with the square root of the calcium score (r = 0.85, p <0.0001). Patients with symptomatic coronary disease and calcium scores <1,000 had stenoses more severe than asymptomatic persons with similar calcium scores. Most asymptomatic adults with elevated calcium scores have nontrivial, nonobstructive CAD or preclinical obstructive CAD, and the relation between coronary calcium score and severity of stenosis is highly significant. These data indicate that electron beam tomography can be used to estimate the severity of CAD in asymptomatic persons.

Section snippets

Patient Selection

We reasoned that the results of regression trials, which indicate substantial benefit of vigorous cholesterol lowering treatments,1, 2 would be sufficiently applicable to patients with elevated calcium scores to justify the risks of coronary arteriography. Therefore, with the approval of the St. Francis Hospital Institutional Review Board (IRB) and the subjects' personal physicians, we invited men and women <70 years of age, who had previously undergone electron beam tomography of the heart, to

Asymptomatic Patients

Of the 256 asymptomatic persons with elevated coronary calcium scores invited to participate in the study, 18 agreed. Mean age and calcium score (± 1 SD) were 55 ± 7 years and 573 ± 504 units for the 18 asymptomatic subjects with elevated calcium scores versus 58 ± 8 years and 471 ± 546 units for the 238 who declined (p = NS for both). The number and distribution of nonlipid risk factors[14] was similar in the 18 asymptomatic subjects who agreed to participate and those who refused (Table 1).

Discussion

Four studies of electron beam tomography in >1,200 symptomatic patients undergoing cardiac catheterization have reported significant differences in calcium scores for patients with normal coronary arteries, nonobstructive coronary disease, and obstructive coronary disease.12, 15, 16, 17 However, the use of these data in the interpretation of coronary calcium scores in asymptomatic adults has been challenged because the prevalence of each of the 3 disease states in the general population is

Acknowledgements

This study was supported by a grant from the St. Francis Hospital Foundation, Roslyn, New York.

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