Understanding coronary artery calcium (CAC) scoring

14th May 2025, NIA Diagnostic Imaging

ASCVD

Coronary artery calcium (CAC) scoring is a well-established, non-invasive imaging technique for assessing cardiovascular risk by identifying and quantifying calcified plaque in the coronary arteries. The CAC score, a direct marker of subclinical atherosclerosis, highly predicts future cardiovascular events, making it an essential tool for clinicians in assessing risk, even in asymptomatic individuals. (4, 5)

CAC scoring facilitates early identification of at-risk individuals by providing an objective assessment of coronary artery disease (CAD) burden, allowing for more targeted and proactive cardiovascular health care. (5).

INTERPRETING CORONARY ARTERY CALCIUM SCORE RESULTS

Through the evaluation of calcified plaque, CAC scoring delivers essential insights regarding cardiovascular risk, even in asymptomatic individuals. The score helps clinicians gauge the extent of atherosclerotic burden, guiding treatment and risk management strategies. (4).

A higher CAC score generally indicates a greater likelihood of future cardiovascular events, prompting aggressive intervention methods. Conversely, a low or zero score indicates a minimal risk of heart disease, potentially reducing the need for immediate treatment. (5).

The CAC score can be interpreted as follows:

Nonetheless, as with any diagnostic test, the CAC score is only one component of the overall risk assessment and should be utilised in conjunction with other clinical factors, including patient history, lifestyle, and other biomarkers to provide a more comprehensive evaluation of cardiovascular risk.

WHEN TO REFER FOR CALCIUM SCORE

To assess which individuals are suitable for a CAC score, the Cardiac Society of Australia and New Zealand (CSANZ) recommends using the Framingham Risk Score. Following an initial evaluation using the Framingham risk score, the CSANZ recommends calcium scoring for asymptomatic persons at intermediate Framingham risk. Moreover, CAC scoring may also be effective for lower-risk patients (6-10% 10-year risk) who have concerning traits that the Framingham Risk Equation does not account for. This group includes Aboriginal and Torres Strait Islander individuals, as well as individuals with a strong family history of early CAD or diabetes. (2)

CAC scores are not beneficial for high-risk or very low-risk patients (≤6% 10-year risk), as they have limited ability to reclassify cardiovascular risk. Additionally, CSANZ does not recommend using calcium scoring for symptomatic patients as there is inadequate evidence to support its use over functional exams such as CT angiography and invasive coronary angiography. (2)

The following image outlines the recommended indications for CAC scoring, as provided by the CSANZ.

CONCLUSION

CAC scoring is a valuable tool for refining cardiovascular risk assessment, especially in asymptomatic individuals at intermediate risk. It supports early intervention and personalised prevention strategies. When used in conjunction with clinical judgment and established guidelines, such as those from the CSANZ, CAC scoring enhances decision-making and contributes meaningfully to preventive cardiology.

At NIA Imaging, we provide advanced coronary artery calcium (CAC) scoring to accurately evaluate your risk

of heart disease. Using cutting-edge technology and a skilled team, we deliver fast, non-invasive scans that support informed treatment and prevention decisions.

REFERENCES

Blaha, M. J., Mortensen, M. B., Kianoush, S., Tota-Maharaj, R., & Cainzos-Achirica, M. (2017). Coronary Artery Calcium Scoring. JACC: Cardiovascular Imaging, 10(8), 923–937. https://doi.org/10.1016/j.jcmg.2017.05.007

Chua, A., Blankstein, R., & Ko, B. (2020). Coronary artery calcium in primary prevention. Australian Journal of General Practice, 49(8), 464–

469. https://doi.org/10.31128/ajgp-03-20-5277

Gami, A., Bisht, S., Satish, P., Blaha, M. J., & Patel, J. (2024). The utility of coronary artery calcium scoring to enhance cardiovascular risk assessment for South Asian adults. Progress in cardiovascular diseases, 84, 7–13. https://doi.org/10.1016/j.pcad.2024.05.001

Goff, D. C., et al. (2021). Coronary artery calcium score and cardiovascular risk prediction: Current insights. Journal of the American College of Cardiology, 78(9), 915-925. https://doi.org/10.1016/j.jacc.2021.07.043

Greenland, P., Blaha, M. J., Budoff, M. J., Erbel, R., & Watson, K. E. (2018). Coronary calcium score and cardiovascular risk. Journal of the American College of Cardiology, 72(4), 434–447. https://doi.org/10.1016/j.jacc.2018.05.027

Hecht, H., Blaha, M. J., Berman, D. S., Nasir, K., Budoff, M., Leipsic, J., Blankstein, R., Narula, J., Rumberger, J., & Shaw, L. J. (2017). Clinical indications for coronary artery calcium scoring in asymptomatic patients: Expert consensus statement from the Society of Cardiovascular Computed Tomography. Journal of cardiovascular computed tomography, 11(2), 157–168. https://doi.org/10.1016/j.jcct.2017.02.010

Khan, S. S., Post, W. S., Guo, X., Tan, J., Zhu, F., Bos, D., Sedaghati-Khayat, B., van Rooij, J., Aday, A., Allen, N. B., Bos, M. M., Uitterlinden, A. G., Budoff, M. J., Lloyd-Jones, D. M., Mosley, J. D., Rotter, J. I., Greenland, P., & Kavousi, M. (2023). Coronary Artery Calcium Score and Polygenic Risk Score for the Prediction of Coronary Heart Disease Events. JAMA, 329(20), 1768–1777. https://doi.org/10.1001/jama.2023.7575

Limpijankit, T., Jongjirasiri, S., Meemook, K., Unwanatham, N., Thakkinstian, A., & Laothamatas, J. (2023). Predictive values of coronary artery calcium and arterial stiffness for long-term cardiovascular events in patients with stable coronary artery disease. Clinical cardiology, 46(2), 171–183. https://doi.org/10.1002/clc.23955

Neves, P. O., Andrade, J., & Monção, H. (2017). Coronary artery calcium score: current status. Radiologia brasileira, 50(3), 182–189. https://doi.org/10.1590/0100-3984.2015.0235

PFO Closure

Furlan AJ, Reisman M, Massaro J, et al. Closure or medical therapy for cryptogenic stroke with patent foramen ovale. N Engl J Med 2012; 366: 991–

A multicenter, randomized, open-label trial of closure with a percutaneous device, as compared with medical therapy alone, in patients between 18 and 60 years of age who presented with a cryptogenic stroke or transient ischemic attack (TIA) and had a patent foramen ovale. The primary end point was a composite of stroke or transient ischemic attack during 2 years of follow-up, death from any cause during the first 30 days, or death from neurologic causes between 31 days and 2 years.

Results:

Primary end point was 5.5% in the closure group as compared with 6.8% in the medical-therapy group (adjusted hazard ratio, 0.78; 95% confidence interval, 0.45 to 1.35; P = 0.37)

Conclusion:

“In patients with cryptogenic stroke or TIA who had a patent foramen ovale, closure

with a device did not offer a greater benefit than medical therapy alone for the

prevention of recurrent stroke or TIA”

2 Saver JL, Carroll JD, Thaler DE, et al. Long-term outcomes of patent foramen ovale closure or medical therapy after stroke. N Engl J Med 2017; 377: 1022–

A multicenter, randomised, open-label trial ,randomly assigned patients 18 to 60 years of age who had a patent foramen ovale (PFO) and had had a cryptogenic ischemic stroke to undergo closure of the PFO (PFO closure group) or to receive medical therapy alone (aspirin, warfarin, clopidogrel, or aspirin combined with extended-release dipyridamole; medical-therapy group). The primary efficacy end point was a composite of recurrent nonfatal ischemic stroke, fatal ischemic stroke, or early death after randomisation.

Results:

Recurrent ischemic stroke occurred in 18 patients in the PFO closure group and in 28 patients in the medical-therapy group, resulting in rates of 0.58 events per 100 patient-years and 1.07 events per 100 patient years, respectively (hazard ratio 0.55; 0.31 – 0.999; P = 0.046)

Conclusion:

“Among adults who had had a cryptogenic ischemic stroke, closure of a PFO was associated with a lower rate of recurrent ischemic strokes than medical therapy alone during extended follow-up.”

Meier B, Kalesan B, Mattle HP, et al. Percutaneous closure of patent foramen ovale in cryptogenic embolism. N Engl J Med 2013; 368: 1083–

A prospective, multicenter, randomised, event-driven trial, randomly assigned patients to medical therapy alone (anti-platelet or warfarin therapy) or closure of the patent foramen ovale.

Results:

9 patients in the closure group and 16 in the medical-therapy group had a recurrence of stroke (hazard ratio with closure, 0.49; 0.22 – 1.11; P = 0.08). The primary analysis of the intentionto- treat cohort showed a nominal 51% hazard rate reduction with closure, but the reduction did not reach significance.

Conclusions:

” …there was no significant benefit associated with closure of a patent foramen ovale in adults who had had a cryptogenic ischaemic stroke.”

Sondergaard L, Kasner SE, Rhodes JF, et al. Patent foramen ovale closure or antiplatelet therapy for cryptogenic stroke. N Engl J Med 2017; 377: 1033–

Multinational trial involving patients with a PFO who had had a cryptogenic stroke, randomly assigned patients to undergo PFO closure plus antiplatelet therapy or to receive antiplatelet therapy alone.

Results:

During a median follow-up of 3.2 years, clinical ischemic stroke occurred in 6 of 441 patients (1.4%) in the PFO closure group and in 12 of 223 patients (5.4%) in the antiplatelet-only group (hazard ratio, 0.23; 0.09 to 0.62; P=0.002).

Conclusions:

“Among patients with a PFO who had had a cryptogenic stroke, the risk of subsequent ischemic stroke was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone; however, PFO closure was associated with higher rates of device complications and atrial fibrillation.”

Mas JL, Derumeaux G, Guillon B, et al. Patent foramen ovale closure or anticoagulation vs. antiplatelets after stroke. N Engl J Med 2017; 377: 1011–

In a multicenter, randomised, open-label trial patients 16-60 years of age who had had a recent stroke attributed to PFO, to transcatheter PFO closure plus long-term antiplatelet therapy, antiplatelet therapy alone or oral anticoagulation.

Results:

No stroke occurred among patients in the PFO closure group, whereas stroke occurred in 14 of the 235 patients in the antiplatelet- only group (hazard ratio, 0.03; 0 to 0.26; P<0.001). Large number of patients discontinued anti-coagulation in the anti-coagulant group and statistical significance was not analysed because the study was not adequately powered to compare outcomes.

Conclusion:

“Among patients who had had a recent cryptogenic stroke attributed to PFO with an associated atrial septal aneurysm or large interatrial shunt, the rate of stroke recurrence was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone. PFO closure was associated with an increased risk of atrial fibrillation.”

Lee PH, Song J-K, Kim JS, et al. Cryptogenic stroke and high-risk patent foramen ovale: the DEFENSE-PFO Trial. J Am Coll Cardiol 2018; 71: 2335–

Patients with cryptogenic stroke and high-risk PFO were divided between a transcatheter PFO closure and a medication-only group.

Results:

No events occurred in the PFO closure group. 12.9% of patients in the medication group had an event (p= 0.023).

Conclusion:

“PFO closure in patients with high-risk PFO characteristics resulted in a lower rate of the primary endpoint as well as stroke recurrence”