Coronary Artery Calcium (CAC) Score Epoch Medical Imaging, St Ives
Coronary artery calcium (CAC) scoring at Epoch Medical Imaging, St Ives. Heart attack risk assessment. Serving the North Shore — Turramurra, Pymble, Gordon & surrounds.
What Is a Coronary Artery Calcium Score and What Does It Measure?
A coronary artery calcium (CAC) score is a fast, low-dose CT scan that quantifies the total amount of calcified plaque within the coronary arteries — providing an objective, numerical measure of coronary artery disease burden.
What it measures and how:
– The CT scanner detects areas of calcification within each of the three main coronary arteries (left anterior descending, right coronary artery, and circumflex artery).
– The volume, density, and extent of calcium deposits in each artery are quantified using the Agatston scoring system.
– Each artery’s score is calculated and summed to give a total CAC score.
– The score reflects the cumulative burden of calcified atherosclerotic plaque in the coronary arteries.
What it means:
– A CAC score of zero means no calcified plaque is detected — a reassuring finding associated with very low short-term cardiovascular event risk.
– Higher scores indicate greater plaque burden and correlate with increasing cardiovascular risk.
– The CAC score is one of the strongest known predictors of future cardiovascular events — stronger than
How the CAC Score Predicts Heart Attack Risk
The coronary artery calcium score is one of the most powerful tools available for cardiovascular risk prediction — and multiple large long-term studies have validated its prognostic value.
How CAC predicts risk:
– People with a CAC score of zero have very low short-term risk of a cardiac event — even in the presence of traditional risk factors. This finding can sometimes allow a more conservative approach to preventive medication.
– Each doubling of the CAC score is associated with approximately a 20–25% increase in cardiovascular event risk over the subsequent years.
– People with CAC scores above 300 have approximately four times the risk of a cardiovascular event compared to those with a score of zero.
– The CAC score improves cardiovascular risk prediction beyond traditional risk calculators — identifying high-risk individuals who appear low-risk on clinical assessment alone, and vice versa.
This makes CAC scoring particularly valuable in patients at intermediate risk — those where the clinical decision about preventive medication or lifestyle intervention is not clear-cut and additional objective information changes management.
What Is a Normal vs High Calcium Score?
CAC scores are interpreted using the Agatston scoring system and compared against age- and sex-matched reference populations.
Score ranges and their clinical significance:
– CAC 0: No detectable calcified plaque. Very low short-term cardiovascular risk — reassuring finding.
– CAC 1–100: Mild calcium — mild coronary artery disease present. Lifestyle modification emphasis. Preventive medication discussion based on overall risk.
– CAC 101–300: Moderate calcium — moderate coronary artery plaque burden. More intensive cardiovascular risk factor management warranted. Preventive medication typically indicated.
– CAC above 300: Extensive calcium — significant coronary artery disease burden. High-intensity risk factor management and preventive medication typically strongly indicated. CTCA or specialist cardiology review often recommended.
– CAC above 400: Very high — aggressive preventive treatment typically warranted. Specialist cardiology review appropriate.
Importantly, CAC scores are interpreted within the clinical context of your age, sex, and risk profile — a score of 50 has different implications in a 40-year-old compared to an 80-year-old. Your GP or cardiologist will
Should I Have a Calcium Score or a Full CTCA?
Both CAC scoring and full CTCA image the coronary arteries — but they provide different types of information and suit different clinical questions.
When a CAC score is most appropriate:
– Asymptomatic patients where the goal is cardiovascular risk stratification — to help decide whether preventive medication is warranted
– When no contrast can be given (allergy, kidney impairment)
When a full CTCA is more appropriate:
– Patients with symptoms (chest pain, breathlessness) requiring detailed coronary assessment
– When non-calcified plaque and luminal stenosis need to be assessed — not captured by CAC scoring alone
– When the question is “is there a significant blockage?” rather than just “how much plaque is present?”
Your GP or cardiologist will advise which investigation is most appropriate for your clinical situation. Both are available at Epoch Medical Imaging in St Ives.
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