Coronary CT-Angiogram (CCTA) for Screening and Risk Stratification of Asymptomatic Individuals – Yes or No?

Coronary Artery Disease accounts for up to one-third of deaths of those above 35years old1. As many patients are asymptomatic, early detection is vital for prevention. Traditionally, most doctors and screening centres use Functional Tests (eg Exercise Stress Test) as the initial test to assess for Coronary Artery Disease. However, since 2016, there has been a great debate among physicians on the use of a Functional vs Anatomical (CT-Coronary Angiogram) test when the UK National Institute for Health and Care Excellence (NICE) updated its Chest Pain guidelines to recommend CCTA for all patients with new onset of chest pain, and Exercise Stress ECG was not recommended for the diagnosis of CAD due to its low accuracy and high rates of subsequent testing2.

While the NICE Chest Pain guideline supports CCTA in Symptomatic patients, the use in Asymptomatic individuals is less clear. There are currently no guidelines that recommend such approach.

Why Yes?

Accuracy and Anatomical information. CCTA has been shown to have the highest accuracy compared with all available non-invasive tests for the detection of angiographically significant stenosis, with a 91% sensitivity and 92% specificity3-5. CCTA can accurately quantify the extent, severity, and composition of coronary plaques. It provides excellent images of coronary artery ostium stenosis and coronary artery anomalies that can be challenging to see (and sometimes missed) in Invasive Coronary Angiogram. While heavily calcified plaques are still a challenge for CCTA, with later generation scanners, we can now perform a scan in a single heartbeat, in patients with irregular heart beat and also rule out Pulmonary embolism and Aortic dissection at the same time.

Evidence of screening benefits in High Risk Asymptomatic populations. There is growing consensus to recommend CCTA for asymptomatic individuals with high 10-year cardiac risk (>20%)6. Diabetes mellitus is considered a CAD equivalent by European and American guidelines. But screening in this group is particularly challenging because angina is often absent, and functional tests less accurate. It has been shown that almost 17% of Asymptomatic Diabetic patients have multivessel disease and high-risk lesions that were consistently associated with the majority of cardiac events during 6-year follow-up7.

Early Treatment. CCTA is the only modality that allows us to identify early Coronary artery plaques. Functional tests will only be positive when the disease is severe enough to limit coronary blood flow. In one study in South Korea, out of 1000 Asymptomatic patients who were randomised to perform a CCTA, 215 were found to have Atherosclerotic plaques8. While there is consensus to whom to treat in symptomatic CAD patients, it is controversial for asymptomatic patients. Nonetheless, in the SCOT-HEART (Scottish Computed Tomography of the Heart; n = 4,146) trial, more patients who underwent CCTA were started on preventive treatment and this group had significantly lower rate of death from coronary heart disease or nonfatal myocardial infarction at 5 years, suggesting benefits of early detection and treatment9.

Being able to see the “disease” can also help convince some patients to go on medications.

Why No?

Radiation. The NICE recommendation is partly based on the assumption that a CCTA radiation dose is about 1-2mSV. This is likely applicable for the latest generation CT-scanners. For 64-slices CT-scanners, the radiation dose can be up to 15mSV. In comparison, most individuals are exposed to natural radiation exposure of 2-3mSV/year.

Contrast Material. Small risk of renal impairment and allergic reaction. Would need a recent Renal Function test before procedure.

Cost. A CCTA costs between RM2000-3000 in many Klang Valley centres currently. A cost that maybe prohibitive to many as a screening test.

Currently, there are a few private Medical and Screening centres that do offer CCTA for cardiac screening. Ideally, the screening packages should be tailored to the needs and expectations of individuals. Coronary CT-Angiogram provides for early detection of Coronary Artery Disease.

References: –

  1. Lloyd-Jones, D. et al. Executive summary: heart disease and stroke statistics–2010 update: a report from the American Heart Association. Circulation 121, 948–954, https://doi.org/10.1161/circulationaha.109.192666 (2010).

  2. National Institute for Health and Care Excellence, “Chest pain. NICE pathway. Manchester: NICE, 2017,” https://pathways.nice.org.uk/pathways/chest-pain.

  3. Arbab-Zadeh A, Di Carli MF, Cerci R, et al. Accuracy of Computed Tomographic Angiography and Single-Photon Emission Computed Tomography-Acquired Myocardial Perfusion Imaging for the Diagnosis of Coronary Artery Disease. Circ Cardiovasc Imaging 2015;8: e003533.

  4. Neglia D, Rovai D, Caselli C, et al. Detection of significant coronary artery disease by noninvasive anatomical and functional imaging. Circ Cardiovasc Imaging 2015;8: e002179.

  5. Danad I, Raijmakers PG, Driessen RS, et al. Comparison of Coronary CT Angiography, SPECT, PET, and Hybrid Imaging for Diagnosis of Ischemic Heart Disease Determined by Fractional Flow Reserve. JAMA Cardiol 2017;2:1100-7.

  6. Wolk MJ, et al. ACCF/AHA/ASE/ASNC/HFSA/HRS/SCAI/SCCT/SCMR/STS 2013 multimodality appropriate use criteria for the detection and risk assessment of stable ischemic heart disease: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2014;63(4):380–406.

  7. 7. Kang SH, Park G-M, Lee S-W, et al. Long-term prognostic value of coronary CT angiography in asymptomatic type 2 diabetes mellitus. J Am Coll Cardiol Img 2016;9:1292–300.

  8. John W. McEvoy, M.B., heart specialist, Johns Hopkins University, Baltimore; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles; May 23, 2011, Archives of Internal Medicine, online

  9. D. E. Newby, M. Williams, A. Hunter et al., “CT coronary angiography in patients with suspected angina due to coronary heart disease (SCOT-HEART): an open-label, parallel-group, multicentre trial,” The Lancet, vol. 385, no. 9985, pp. 2383–2391, 2015.

Dr Lau Gin Choy

Consultant Cardiologist & Physician
Resident Consultant
Specialty
Cardiology
Qualifications
MD (Can.), MRCP (UK)
Suite Number
Level 1 - H7
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Cantonese, English, Malay

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