What is the role of MDCT in the workup of coronary artery atherosclerosis?

Updated: Apr 09, 2021
  • Author: Sandy N Shah, DO, MBA, FACC, FACP, FACOI; Chief Editor: Yasmine S Ali, MD, MSCI, FACC, FACP  more...
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Answer

Multidetector computed tomography (MDCT) can allow excellent visualization of the coronary arteries, but its relatively high radiation dose is one of the limitations of this approach. Newer generations of CT scanners may be able to reduce the required radiation exposure to make this technology more promising for screening asymptomatic patients. Low-dose CT attenuation correction (CTAC), which is performed for hybrid positron emission tomography (PET)/CT and single-photon emission computed tomography (SPECT)/CT myocardial perfusion imaging (MPI) can visually assess coronary artery calcium with high agreement with the Agatston score (AS). [34] These scans should routinely be assessed for visually estimated coronary artery calcium.

However, guidelines that address the use of CAD imaging tests may disagree. A study by Ferket, et al found several guidelines for risk assessment of asymptomatic CAD to have conflicting recommendations. [35] More research, especially randomized controlled trials, are needed in order to establish the actual impact imaging has on clinical outcomes.

A meta-analysis by Bamberg et al concluded that coronary CT angiography is an important tool in detecting the presence and extent of CAD and independent predictors of significant coronary stenosis and other cardiovascular events. [36] Glineur et al found that preoperative angiography predicts graft patency in the right gastroepiploic artery and right internal thoracic artery, whereas the flow pattern in saphenous vein grafts is significantly less influenced by quantitative angiographic parameters. [37]

The successful use of coronary CT angiography in the Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter (CONFIRM) Registry study suggests that this modality may provide a suitable alternative to cardiac stress testing and conventional angiography in the evaluation of patients with a low to intermediate cardiovascular disease risk. [22]

Plaque characteristics on CT angiography appear to help identify high-risk coronary lesions. In a study addressing the use of CT angiography to detect and characterize coronary plaques prone to rupture, Maurovich-Horvat et al identified several features that were associated with vulnerable plaques. [38, 39] Such high-risk features included large plaque volume, low CT attenuation, the “napkin-ring sign,” positive remodeling, and spotty calcification.

The investigators’ findings suggest that coronary CT angiography can be effectively used in this setting for purposes beyond simply ruling out coronary stenosis. [38, 39] For this modality to achieve optimal prognostic value in the identification of high-risk plaques, however, quantitative and qualitative plaque characteristics (eg, plaque volume and the napkin-ring sign) should be combined with functional measures (eg, fractional flow reserve).

Min et al suggest patients with CAD have an increased mortality risk that was highest among those with 3-vessel disease or left main disease. Conversely, the lack of CAD portended a good prognosis. [40]


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