Coronary computed tomographic angiography (CCTA) is a noninvasive radiology test used to evaluate for coronary artery stenosis by detecting high-risk atherosclerotic plaques and their volume and location.¹ In 2021, the American College of Cardiology/American Heart Association Joint Committee recommended CCTA over invasive coronary angiography (ICA) or functional imaging for intermediate-risk patients with stable chest pain and no known coronary artery disease (CAD) to rule out coronary stenosis.²

Intermediate risk can be defined using different clinical decision pathways such as the HEART (history, electrocardiography, age, risk factors, and troponin) score for major cardiac events and the Thrombolysis in Myocardial Infarction score. The classification system groups CCTA findings from 0 to 5 based on the degree of coronary stenosis and location and recommends management options (Table 1).³

ACCURACY

A study comparing CCTA with ICA as the reference standard in intermediate- to high-risk patients (n = 64 patients; 827 segments) showed that CCTA had a diagnostic accuracy of 96% for detecting 50% or greater luminal stenosis (sensitivity = 87%; specificity = 97%; positive likelihood ratio = 29; negative likelihood ratio = 0.13). In segments with 70% or greater luminal stenosis, diagnostic accuracy was 99% (sensitivity = 96%; specificity = 99%; positive likelihood ratio = 96; negative likelihood ratio = 0.04). For coronary artery segments analyzed in this study, 1% were considered uninterpretable because of motion artifacts, extensive calcifications, small vessel diameter, or blooming artifact from a stent.⁴

A meta-analysis of randomized controlled trials and observational studies showed better diagnostic accuracy with CCTA over conventional functional testing, including exercise electrocardiography and single-photon emission computed tomography. Patients with suspected stable CAD and without known history of CAD were included in the study, which used ICA as the reference standard. The results of this study are summarized in Table 2.⁵

BENEFIT

CCTA is noninvasive and widely available. The test provides high-quality imaging, can be used in patients with cardiac devices, and has high a patient satisfaction rate compared with ICA.^6,7

The relative risk of fatal myocardial infarction (MI), stroke, and all-cause mortality is similar for CCTA and ICA.8 Use of CCTA demonstrated fewer nonfatal MIs and coronary heart disease deaths over 5 years (2.3% vs. 3.9%; number needed to treat = 63) by identifying at-risk patients who may need preventive therapies.⁹

One retrospective study of patients who received elective ICA (n = 398,000; median age = 61 years) found that 62.4% of patients did not have CAD (defined as less than 20% luminal stenosis in all vessels).¹⁰ In a randomized study, major procedural complications, mostly from intravascular access leading to nonfatal MI and nonfatal stroke, were less likely with CCTA (0.5%) than ICA (1.9%).¹¹ Within the first year of evaluation, CCTA is less expensive than functional testing.¹²

HARMS

Requirements for imaging include a heart rate between 60 and 65 beats per minute (met by taking 50 to 100 mg of oral metoprolol the night before and 1 hour prior to the examination), the ability for 18-gauge antecubital access for contrast infusion with good kidney function, patient ability to hold their breath for 5 to 10 seconds, and electrocardiogram monitoring to achieve diastolic imaging.⁶ Extensive coronary artery calcifications may cause blooming artifact on CCTA, which can result in overestimation of the degree of stenosis.¹³ CCTA is also less effective in areas of in-stent re-stenosis, although newer scanners have shown improved performance of up to 91% in these areas.¹⁴

Radiation exposure from CCTA ranges from 1.5 to 5.0 mSv, approximately 15 to 50 times more than traditional chest radiography (0.1 mSv).⁶ CCTA has been shown to result in higher rates of ICA use compared with other forms of functional testing.¹¹ Other harms may include allergic reaction to contrast, contrast-induced nephropathy, and intravenous access complications such as cellulitis.⁶

COST

The average cost of CCTA is $539 when using the MDsave program with no insurance.¹⁵ With Medicare reimbursement, the average cost is $360, which includes health professional and facility fees.¹⁶

BOTTOM LINE

CCTA is preferred over ICA for evaluation of stable chest pain in intermediate-risk patients without known CAD because it is noninvasive, widely available, and has high patient satisfaction and lower procedural complications.