Measurement of coronary calcium scores or exercise testing as initial screening tool in asymptomatic subjects with ST-T changes on the resting ECG: an evaluation study

Abstract

Background: Asymptomatic subjects at intermediate coronary risk may need diagnostic testing for risk stratification. Both measurement of coronary calcium scores and exercise testing are well established tests for this purpose. However, it is not clear which test should be preferred as initial diagnostic test. We evaluated the prevalence of documented coronary artery disease (CAD) according to calcium scores and exercise test results.

Methods: Asymptomatic subjects with ST-T changes on a rest ECG were selected from the population based PREVEND cohort study and underwent measurement of calcium scores by electron beam tomography and exercise testing. With calcium scores > or =10 or a positive exercise test, myocardial perfusion imaging (MPS) or coronary angiography (CAG) was recommended. The primary endpoint was documented obstructive CAD (>/=50% stenosis).

Results: Of 153 subjects included, 149 subjects completed the study protocol. Calcium scores > or =400, 100-399, 10-99 and <10 were found in 16, 29, 18 and 86 subjects and the primary endpoint was present in 11 (69%), 12 (41%), 0 (0%) and 1 (1%) subjects, respectively. A positive, nondiagnostic and negative exercise test was present in 33, 27 and 89 subjects and the primary endpoint was present in 13 (39%), 5 (19%) and 6 (7%) subjects, respectively. Receiver operator characteristics analysis showed that the area under the curve, as measure of diagnostic yield, of 0.91 (95% CI 0.84-0.97) for calcium scores was superior to 0.74 (95% CI 0.64-0.83) for exercise testing (p = 0.004).

Conclusion: Measurement of coronary calcium scores is an appropriate initial non-invasive test in asymptomatic subjects at increased coronary risk.

Figure 1

Decision protocol*. *see text for explanation. Abbreviations: CAG, coronary angiography; MPS, myocardial perfusion scintigraphy.

Figure 2

Endpoints according to coronary calcium scores and exercise test results. (a) primary endpoint (documented significant obstructive coronary artery disease) (b) secondary endpoint (Class I or IIa indication for revascularization procedure). Abbreviations: neg., negative; nond., nondiagnostic; pos., positive

Figure 3

Receiver operator characteristic curves. (a) primary endpoint (documented significant obstructive coronary artery disease) Area under the curve for coronary calcium scores 0.91 (95% CI 0.84–0.97); Area under the curve for exercise test 0.74 (95% CI 0.64–0.83). (b) secondary endpoint (Class I or IIa indication for revascularization procedure) Area under the curve for coronary calcium scores 0.90 (95% CI 0.78–1.00); Area under the curve for exercise test 0.73 (95% CI 0.52–0.93)