Clinical Question: Is the coronary artery calcium score useful in the prediction of coronary heart disease (CHD) in asymptomatic adults?
Study Design: Cohort (prospective)
Synopsis: The Framingham risk score is used commonly to assess individual CHD risk and guide the intensity of preventive treatment. The authors of this study wanted to determine whether risk assessment and preventive treatment strategies could be further improved with the addition of the coronary artery calcium score.
A total of 1,461 asymptomatic adults with at least one coronary risk factor had computed tomographic (CT) examination of their coronary arteries at baseline. After CT scanning, 87.5 percent of the patients were contacted yearly for up to 8.5 years (mean = seven years). Patients with diabetes were excluded. Outcomes were assessed by persons with no knowledge of individual patient data.
Compared with a Framingham risk score of less than 10 percent, a score of more than 20 percent predicted the risk of myocardial infarction or CHD (hazard ratio [HR] = 14.3;95 percent confidence interval [CI], 2.0 to 104; P = .009). Compared with a coronary artery calcium score of zero, a coronary artery calcium score of more than 300 also was predictive of CHD risk (HR = 3.9; 95 percent CI, 2.1 to 7.3; P < .001). The combination of coronary artery calcium score and the Framingham risk score was more accurately predictive of risk than either score alone when the initial Framingham risk score was between 10 and 19 percent.
Bottom Line: An elevated coronary artery calcium score more accurately predicts CHD risk in adults with an initial Framingham risk score in the 10 to 19 percent range. We now need to determine whether adding this test to the management of these patients will change treatment, improve outcomes, or be cost effective. This is one more test to add to the list of others (e.g., C-reactive protein, carotid intimal–media thickness, homocysteine level) lacking this crucial evidence of effectiveness. (Level of Evidence: 1b)