Using noncontrast cardiac CT and coronary artery calcification measurements for cardiovascular risk assessment and management in asymptomatic adults

Abstract

The presence of mural calcification has, for decades, been recognized as a marker for atheromatous plaque in the coronary arteries and the aorta, but only in the past decade has the application of noncontrast computed tomography (CT) been shown to be a reproducible, safe, and convenient test, which now is available worldwide. However, awareness of coronary artery calcium scanning is insufficient and the practitioner must be aware of the available literature as well as understanding clinical recommendations for applications and interpretation. It is best applied in the medium/intermediate risk, asymptomatic adult regardless of ethnicity across broad age ranges for both men and women; additional prognostic information is also afforded from the calcium distribution in the coronary artery system. Additionally, information can also be derived from the same CT scan regarding heart and aorta size and assessment of the epicardial fat pad (an anatomic marker for the metabolic syndrome). Details of how this test can aid in cardiovascular risk assessment and management in adults are provided.

Keywords: National Cholesterol Education Program Adult Treatment Plan III (NCEP ATP III); coronary artery calcium; coronary artery disease; electron beam computed tomography; epicardial fat; multidetector computed tomography.

Figure 1

Examples of noncontrast coronary calcium CT scans at the base of the heart: top left, CAC score = 0; top right, CAC score = 29; bottom left, CAC score = 250; bottom right, CAC score = 1200. Abbreviations: CT, computed tomography; CAC, coronary artery calcification.

Figure 2

Graphical representation of data presented by Hoff showing distribution of total CAC scores in 35,246 men and women. The red line represents the median score as a function of age. Superimposed are information regarding determination of ‘heart age’ (see text for details) in a 50 year old man with a CAC score of 100 and a 55 year old woman with a CAC score of 50. Abbreviation: CAC, coronary artery calcification.

Figure 3

Pie chart representing the distribution of coronary calcium scores in >5,000 asymptomatic, middle aged adults referred to one scanning center for assistance in cardiovascular risk stratification. Subsequent stratification of risk is altered based upon the total calcium scores (see text for detail) as very low (VL = <0.1%/year), low (L = <1%/year), true intermediate (I = 1%–2%/year), high (H = >2%/year), and very high (VH = >3%/year).

Figure 4

A single, mid LV slice from a noncontrast CT of the heart (ie, a ‘heartscan’) demonstrating the epicardial fat distribution in a patient without metabolic syndrome (Left arrow) and a patient with known metabolic syndrome (right arrow). See text for details. Abbreviations: LV, left ventricle; CT, computed tomography.