Coronary heart disease risk assessment and characterization of coronary artery disease using coronary CT angiography: comparison of asymptomatic and symptomatic groups

Aim

To evaluate the prevalence of coronary artery disease (CAD) in relation to risk of coronary heart disease (CHD) and assess plaque characteristics from coronary computed tomography (CT) angiography in asymptomatic and symptomatic patients.

Materials and methods

Three hundred and ninety consecutive patients [asymptomatic group, n = 138; symptomatic group (atypical or non-anginal chest pain), n = 252] were retrospectively enrolled. They were subsequently classified into three CHD risk categories, based on the National Cholesterol Education Program guidelines, and 10 year risks of coronary events were calculated using Framingham risk score. CT was evaluated for stenosis, plaque composition, and coronary calcium scores.

Results

CAD was observed in 42% of the asymptomatic group and 62% of the symptomatic group. In the former, the prevalence of CAD in low-, moderate- and high-risk subgroups was 21.4, 47.4 and 65%, respectively, and was 33.3, 74.4, and 72.4% in the symptomatic group. Framingham 10-year risks of coronary events were significantly higher in patients with CAD than in normal participants, and receiver operating characteristics curves showed that discriminatory power was poor in the asymptomatic group and symptomatic men, and good in symptomatic women. Of the participants in the asymptomatic group, 12% exhibited only non-calcified plaques and of the symptomatic group, 7% exhibited only non-calcified plaques. The coronary calcium score was significantly higher for significant stenosis than for non-significant stenosis in both groups.

Conclusions

The prevalence of CAD was not negligible even in subgroups with low-to-moderate CHD risk. Additionally, the Framingham risk score was effective for predicting CAD only in symptomatic women. Coronary calcium scores correlated with significant stenosis; however, a sizeable percentage of both groups had only non-calcified plaques.

Introduction

The initial approach to the management of individuals at risk for coronary heart disease (CHD) is careful assessment of the patient’s overall risk. Traditional risk assessment tools, such as the Framingham risk score or the National Cholesterol Education Program (NCEP) guidelines, have been widely used for the assessment of patient risk.¹ However, there is growing evidence that these traditional risk assessment tools, based on risk factor analysis, have substantial limitations when used to guide individual therapy.2, 3, 4 For example, patients in the high-risk CHD group with limited or no plaque formation may be subjected to life-long drug therapy, whereas others with low‑risk CHD, but substantial plaque formation, might be undertreated or not treated at all.

Coronary computed tomography (CT) angiography (CCTA) is a very useful, non-invasive method for the diagnosis of coronary artery disease (CAD), because it has high diagnostic accuracy and provides direct visualization of plaques, an advantage over conventional coronary angiography.5, 6 However, the application of CCTA has been limited due to the associated radiation exposure.⁷ Thus, according to the appropriateness criteria for cardiac CT created by the American College of Cardiology Foundation (ACCF), CCTA is not recommended for asymptomatic individuals with low-to-moderate CHD risk. Even in those patients with high CHD risk, the appropriateness criteria for CCTA use are uncertain.⁸

The purpose of the present study was to evaluate the prevalence of CAD in accordance with traditional CHD risk assessment, as well as to assess plaque characteristics in asymptomatic and symptomatic patients. The usefulness of Framingham risk score for the prediction of CAD using receiver operating characteristics (ROC) analysis was also evaluated.