Guidelines for interpretation of electron beam computed tomography calcium scores from the Dallas Heart Disease Prevention Project

Subclinical coronary artery disease as detected by coronary computed tomography angiography in an asymptomatic population

Background and Objectives

Primary prevention of coronary artery disease (CAD) has become a public health issue, according to increasing awareness of the substantial risks posed by asymptomatic atherosclerosis. The aims of this study were to determine the prevalence and characteristics of subclinical CAD using coronary computed tomography angiography (CCTA), and to evaluate the role of this advanced technology in identifying subclinical CAD in asymptomatic Korean individuals, compared with conventional risk stratification.

Subjects and Methods

We enrolled 4,320 consecutive asymptomatic individuals (61% males, aged 50±9 years), who underwent 64-slice CCTA during a routine health check.

Results

Coronary artery plaques were present in 1,053 (24%) individuals. Significant stenosis (diameter stenosis ≥50%) was identified in 139 (3%) subjects, and most of the significant lesions (87%) were located in the left anterior descending artery. CCTA revealed noncalcified plaques in 5% of subjects with a coronary calcium score of zero (n=801). Although 25% (n=10) of those with noncalcified plaque had significant stenosis, most of them (90%) were classified into low- or moderate-risk groups according to National Cholesterol Education Program risk stratification guidelines. In a young population (age ≤55 years for males, ≤65 years for females), 30% of subjects with significant stenosis were classified into a low-risk group and 60% had low (0 to 100) calcium scores.

Conclusion

Subclinical CAD in asymptomatic individuals cannot be ignored for its considerable prevalence, CCTA may be helpful in identifying at-risk subclinical CAD in a noninvasive manner, especially in the young and traditionally low-risk population.

Assessment of clinically silent atherosclerotic disease and established and novel risk factors for predicting myocardial infarction and cardiac death in healthy middle-aged subjects: rationale and design of the Heinz Nixdorf RECALL Study. Risk Factors, Evaluation of Coronary Calcium and Lifestyle

BACKGROUND

In view of consistently high cardiovascular morbidity and mortality rates, international efforts are aimed at developing tools for more precise risk prediction to allow preventive treatment targeted at high-risk individuals. Direct visualization of anatomic, preclinical atherosclerotic disease has the potential for individualized risk discrimination. Further, a variety of risk factors are actively evaluated, including markers of the activity of atherosclerotic disease, thrombogenic risk, and genetic polymorphisms.

METHODS

The Heinz Nixdorf RECALL (Risk Factors, Evaluation of Coronary Calcium and Lifestyle) study is a population-based, prospective cohort study of the comparative value of modern risk stratification techniques for "hard" cardiac events. It is designed and powered to define the relative risk associated with the specific extent of coronary atherosclerosis measured by means of electron-beam computed tomography (EBCT)-derived coronary calcium quantities for myocardial infarction and cardiac death in 5 years in 4200 males and females aged 45 to 75 years in an unselected urban population from the large, heavily industrialized Ruhr area. Additionally, the predictive values of conventional cardiovascular risk factors, new candidate and socioeconomic risk factors, certain genetic polymorphisms, and direct signs of subclinical disease are examined with the ankle-brachial index, resting and stress electrocardiograms, and determination of carotid artery intima-media thickness. Prospective clinical risk-benefit and health economic analyses are an inherent part of the study. Study findings with established clinical significance are reported to the participants, but the EBCT findings are withheld until the conclusion of the study.

CONCLUSIONS

The Heinz Nixdorf RECALL study will define appropriate methods for identifying high-risk subgroups in the general urban population who may derive the greatest benefit from preventive treatment.