Cardiac risk stratification: role of the coronary calcium score

Abstract

Coronary artery calcium (CAC) is an integral part of atherosclerotic coronary heart disease (CHD). CHD is the leading cause of death in industrialized nations and there is a constant effort to develop preventative strategies. The emphasis is on risk stratification and primary risk prevention in asymptomatic patients to decrease cardiovascular mortality and morbidity. The Framingham Risk Score predicts CHD events only moderately well where family history is not included as a risk factor. There has been an exploration for new tests for better risk stratification and risk factor modification. While the Framingham Risk Score, European Systematic Coronary Risk Evaluation Project, and European Prospective Cardiovascular Munster study remain excellent tools for risk factor modification, the CAC score may have additional benefit in risk assessment. There have been several studies supporting the role of CAC score for prediction of myocardial infarction and cardiovascular mortality. It has been shown to have great scope in risk stratification of asymptomatic patients in the emergency room. Additionally, it may help in assessment of progression or regression of coronary artery disease. Furthermore, the CAC score may help differentiate ischemic from nonischemic cardiomyopathy.

Keywords: CAC; Framingham; angiography; cardiomyopathy; chest pain; coronary artery disease; coronary calcium scoring; risk factors; risk stratification.

Figure 1

Predicted seven-year event rate from Cox regression model for CHD death or nonfatal MI for different categories of FRS or CAC score. The event rates are stratified by four levels of FRS and four different levels of calcium score. Analysis showed a statistically significant difference between and calcium >300 and other groups for FRS categories >10% CHD risk. Copyright © 2004, American Medical Association. All rights reserved. Adapted with permission from Greenland P, LaBree L, Azen SP, Doherty TM, Detrano RC. Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals. JAMA. 2004;291(2):210–215. Abbreviations: CACS, coronary artery calcium score; CHD, coronary heart disease; FRS, Framingham Risk Score; MI, myocardial infarction.

Figure 2

Event rate according to calcium score category. Copyright © 2005, American Heart Association. All rights reserved. Adapted with permission from Vliegenthart R, Oudkerk M, Hotman A, et al. Coronary calcification improves cardiovascular risk prediction in the elderly. Circulation. 2005;112(4):572–577. Abbreviations: CVD, cardiovascular disease; CHD, coronary heart disease; FRS, Framingham Risk Score.

Figure 3

Survival curves, free of CHD A) and CVD B) events, according to calcium score. Copyright © 2005, American Heart Association. All rights reserved. Adapted with permission from Ehara S, Kobayashi Y, Yoshiyama M, et al. Circulation. 2005;112: 572–577. Abbreviations: CHD, coronary heart disease; CVD, cardovascular disease.

Figure 4

Unadjusted Kaplan–Meier cumulative event curve for coronary events among participants with calcium score 0, 1–100, 101–300, and >300. Panel A shows the rate of major coronary events (MI and death from CHD); Panel B shows the rates for any coronary event. Differences between all curves are statistically significant. Copyright © 2008, Massachusetts Medical Society. All right reserved. Adapted with permission from Detrano R, Guerci AD, Carr JJ, et al. N Engl J Med. 2008:358: 1336–1345.