What is the purpose of a Computed Tomography (CT) scan of the coronary arteries?

From the Guidelines

CT of coronary arteries, also known as coronary CT angiography (CCTA), is a highly recommended non-invasive imaging test for patients with intermediate risk of coronary artery disease, those with atypical chest pain, or as a follow-up to abnormal stress tests, as it provides detailed images of coronary arteries, calcium deposits, and potential blockages, allowing for earlier intervention with lifestyle changes or medications, as supported by the most recent study 1.

Key Points to Consider

• The procedure involves injecting contrast material through an IV while the patient lies on a CT scanner table, and patients should avoid caffeine and food for 4-6 hours before the test.
• Beta-blockers, such as oral metoprolol 50-100mg given 1 hour before the scan, or IV metoprolol 5mg increments up to 20mg immediately before imaging, may be used to slow heart rate for better image quality.
• Patients with allergies to contrast should receive premedication with prednisone 50mg at 13,7, and 1 hour before the procedure, plus diphenhydramine 50mg 1 hour before.
• The test exposes patients to radiation (typically 2-5 mSv), but the benefits of early detection and intervention outweigh the risks, as demonstrated by the high negative predictive value (NPV) of CCTA in excluding obstructive CAD 1.

Benefits of CCTA

• High accuracy in detecting coronary artery disease, with a reported sensitivity of 95% and specificity of 83% in the CCTA ACCURACY trial 1.
• Ability to detect coronary artery disease before symptoms develop, allowing for earlier intervention with lifestyle changes or medications.
• High NPV, making it a valuable tool for excluding obstructive CAD and reducing the need for invasive coronary angiography.

Clinical Applications

• CCTA is recommended for patients with intermediate risk of coronary artery disease, those with atypical chest pain, or as a follow-up to abnormal stress tests.
• It can also be used to evaluate coronary artery disease in asymptomatic patients with high risk factors, as supported by the ACR Appropriateness Criteria 1.
• The entire procedure takes about 15-30 minutes, and patients can typically resume normal activities immediately afterward.

From the Research

CT of Coronary Arteries

• The introduction of Cardiac Computed Tomography (CCT) has changed the paradigm in the field of diagnostic cardiovascular medicine, with CCT being the primary tool in the assessment of suspected Coronary Artery Disease (CAD) 2.
• Cardiac CT angiography (CCTA) is emerging as a front-line non-invasive diagnostic test for CAD, with evidence supporting its clinical utility in diagnosis and prevention 3.
• CCTA offers several advantages beyond other testing modalities, including the ability to identify and characterize coronary stenosis severity and pathophysiological changes in coronary atherosclerosis and stenosis 3.

Clinical Indications and Applications

• The primary role of CCT in suspected CAD will progressively become the standard approach, with any situation requiring anatomy of the heart and thoracic vessels/structures to be approached using CT first, whenever possible 2.
• Cardiac CT is recommended as the first-line investigation for all patients presenting with chest pain due to suspected coronary artery disease, according to the National Institute for Health and Care Excellence (NICE) Clinical Guideline 95 update 4.
• CCTA can provide personalized risk assessment and guide targeted treatment, with emerging applications including functional assessment using CT-derived fractional flow reserve, peri-coronary inflammation, and artificial intelligence (AI) 3.

Diagnostic Accuracy and Cost-Effectiveness

• Cardiac CT offers a detailed anatomical assessment of coronary artery disease comparable to invasive coronary angiography, with high sensitivity and low cost 4.
• Randomized controlled trials have demonstrated that cardiac CT improves diagnostic certainty when incorporated into chest pain pathways 4.
• The use of cardiac CT as a first-line test can help reduce the dependence on invasive investigations and improve risk stratification, leading to more cost-effective care pathways 4.