What is Coronary Calcium Score?
In this post, I will briefly discuss the importance of coronary calcium score as an emerging valuable tool to assess the future risk of a heart attack. When it can be useful, when it can cause harm, and some other specifics of the test.
For decades, investigators have been trying to discover the “risk factors” that increase the chance of heart attack. They have identified many of these risk factors through years of intensive and elegant research . These include Smoking, Obesity, a sedentary lifestyle, high cholesterol (known as hypercholesterolemia), high blood pressure (hypertension), positive family history of heart attack, menopause, inflammatory diseases like rheumatoid arthritis, and last but not least, Diabetes. Research has proven we can significantly reduce the risk of heart attack by modifying these factors.
Despite these massive efforts and discoveries, still, many individuals suffer from a heart attack prematurely without having any or only a few of the “traditional” risk factors. This fact suggests that our current risk calculators, developed based on “traditional risk factors,” are far from perfect. They can potentially miss many “preventable” cases of heart attack.
During the past 15 years, coronary calcium score has emerged as a reliable “predictive” test to assess someone’s risk of future heart attack by identifying atherosclerosis.
Atherosclerosis, an inflammatory process in the arterial wall, starts at a young age and forms “plaques” in the arterial wall. Plaques are the main precursors of myocardial infarction. As we age, the process of calcification begins in these plaques. We can identify the calcium in x-ray images, confirming the underlying plaque in the arterial wall.
Figure 1: This CT scan, which belongs to a 60-year-old asymptomatic man, shows significant calcification of the LAD and RCA arteries. It implies that under this bulk of calcium, the process of “atherosclerosis” is progressing fast, which, if not controlled, can result in acute coronary syndromes (heart attack).
He was initially labelled as “low-risk” based on traditional risk factor calculations. But this mere new fact (high coronary calcium score) will change his previous “low risk” status to “high-risk.”
When should you consider checking your calcium score?
There has been significant debate as to what clinical situation a coronary calcium score should be considered. CAC Score is a preventive test and should not be used in symptomatic patients (if someone has chest pain or shortness of breath). It is another piece of the puzzle to shed more light on someone’s “future risk of a Heart Attack”.
Before considering a calcium score, it is crucial to calculate the patient’s baseline risk of a heart attack. This can be done by many online calculators like this online calculator from the American College of Cardiology. It needs a few baseline information like the presence of Diabetes, Hypertension or high cholesterol levels. Smoking status, age and medications are other components. Based on this information, a 10-year risk estimate is generated. The patient will be categorised either as low-risk, intermediate-risk, and high-risk for future heart attacks.
To illustrate how the CAC score check can be helpful, here I present a typical case.
CASE: A 55-year-old man presents to you after his close friend suffered a massive myocardial infarction. They have been colleagues and used to exercise regularly with weekly swimming, cycling, and running regularly and intensely. He does not smoke, eats healthy, and does not have any significant family history of ischaemic heart disease. His cholesterol is on the low side, and has mild hypertension, which is well controlled with a low-dose antihypertensive. He is not complaining of any symptoms indicative of angina. He insists that his friend had the same profile and was at low risk for myocardial infarction. In this scenario, a test that can add significant weight and information to stratify his risk for future IHD is a coronary calcium score. He performs a CAC score, which comes back as 300. A calcium score at this level will move him from the low-risk category to moderate-high-risk category immediately. He will undoubtedly benefit from intensive reduction of his LDL to 1.4-1.6 mmol/L and the addition of Aspirin.
This case clearly illustrates that coronary artery calcium score should only be considered in “low to intermediate-risk” patients. A high coronary calcium score can change someone’s risk from low to high but not the other way. A low or even zero calcium score does not change the status of a high-risk patient to a low-risk. A “high risk” individual will remain “high risk” regardless of their calcium score. High-risk patients should be on intensive therapy with Statins and Aspirin, and encouraged to change their lifestyle.
What is the ideal age to consider coronary artery calcium scoring?
Calcium scores should be considered in people between 45-70 years of age. This does not mean that people below 40 or above 70 cannot have the test, but the interpretation should be guarded outside this range. Under 40, the zero score’s negative predictive value is not high since there has not been enough time for the lipid-rich plaques to calcify. This core may be misleading and lead to false reassurance. On the other hand, a high calcium score has a very high positive predictive value at a young age. It shows that they already have coronary plaques with a subsequent high risk of future IHD.
Above the age of 70, nearly everyone has calcification of the coronary arteries. Having a positive score in the elderly, unless significantly elevated, does not necessarily signify high risk. On the other hand, a calcium score of 0 in this age group has a very high negative predictive value; in other words, very reassuring.
So rather than concentrating on the absolute number of the calcium score, you should see where you are compared to the people your age. This “percentile” gives you a much more accurate risk assessment. You can use MESA CAC score calculator to understand your risk better.
How should we interpret a calcium score of 0?
Coronary artery calcium score should always be interpreted in the context of other risk factors and never solely. A calcium score of 0 in a low-risk patient is highly reassuring. However, the same score in someone who smokes and has high cholesterol or blood pressure is much less predictive. Other risk factors should always be treated and dealt with diligently, regardless of the coronary calcium score. Patients should always be advised against smoking, treated for hypercholesterolemia, hypertension, and diabetes and be encouraged to perform regular exercise and eat healthy, even with a calcium score of 0. To show the importance of this fact, I have briefly discussed two examples of severe coronary artery disease despite a calcium score of zero in two high risk patients, in a separate post.
How should a high calcium score be interpreted?
Coronary artery calcium score should be interpreted according to age. A calcium score of 20 in a 70-year-old person is low but is significantly elevated for 35-40-year-old. Usually, any calcium score above 300-400 should be considered considerably elevated. Intensive medical therapy and risk factor modifications are strongly recommended.
Should the calcium score ever be repeated?
If the calcium was elevated, it should not be repeated ever. The patient is at high risk, and they need intensive treatment for their risk factors and lifestyle modifications. There is also mounting evidence that statins and Aspirin would reduce the risk of heart attack significantly in this scenario.
If the calcium score was 0, in the lower tier of the age group, the test might be repeated after 5 years “to look for a significant rise”. This is especially more sensible if they have a few risk factors like high cholesterol or blood pressure.
If someone is already on statin therapy, should we bother checking their coronary artery calcium score?
If they take Aspirin and statin with an LDL close to 1.5 mmol/L, there is no need to check the calcium score. But suppose the LDL is not on target (let’s say above 2 mmol/L), and they have a very high coronary artery calcium score. This suggests that their cholesterol management needs to be intensified. I also find it a potent motivating factor for patients to change their lifestyles and adhere to medical treatment.
In the following video, I present a real case and show how Coronary Calcium Score can change someone’s cardiovascular risk profile, and how it can be helpful or harmful in different scenarios.
Coronary Calcium Score video:
Frequently asked questions:
To learn more about the cost of a CAC score and how it is done, check this Coronary Calcium Score WebStory.
At any age, 0 is the ideal and normal calcium score. A score of 0 means no “calcified” plaque exists in the coronary arteries. However, it is imperative to note that if you have “non-calcified” plaques, the score would still be 0, but falsely reassuring. This is a big caveat of the calcium scoring test, which should be kept in mind.
Calcium score indicates the future risk of a heart attack. If elevated, instead of focusing on that number, you should focus on the ways to reduce the overall risk of cardiovascular disease. These include smoking cessation, exercise, a healthy diet and statin therapy, depending on the score and cholesterol levels. After initiating statins and starting exercise, your score might increase. This is not a “bad thing” and means that plaques are hardening and becoming more stable with a reduced risk of a heart attack. In this video, Coronary Calcium Score: how to interpret, I have explained further in detail.
No. An Echocardiogram is a test to check the heart chambers and valves and does not show coronary arteries or their calcification.
No. A stress test or stress echocardiogram is a test to check your exercise tolerance and can help identify coronary artery narrowing or blockages. Like echocardiograms, we use ultrasound waves for this test, which cannot identify coronary calcifications. The stress test is an entirely different type of investigation and can’t be compared to a coronary calcium score test. They have very different indications and implications.
Most places that do CT Coronary Angiogram (CTCA) routinely include calcium scores in the final report. However, some places do not report calcium scores in the final CTCA report unless specifically requested. Ask your doctor to request a calcium score as well if you have a CT Coronary Angiogram.
This question requires a blog post as there is great debate in this regard. Suffice it to say that I order CTCA in patients with chest pain or abnormalities on their stress echocardiogram. CT Coronary Angiogram is a “diagnostic” test. However, coronary calcium score is a test we order in people who don’t have complaints and is a “predictive” test.
The coronary artery calcium score is only one piece of overall risk factor puzzle. Like any other test in medicine, it has pros and cons, can be helpful or harmful and should be used judiciously. It clarifies someone’s risk for future ischaemic heart disease and should never be interpreted solely without having the whole picture in mind. It should never be used to investigate chest pain and should not be ordered in high risk patients.
- DeGoma EM, Knowles JW, Angeli F, Budoff MJ, Rader DJ. The evolution and refinement of traditional risk factors for cardiovascular disease. Cardiol Rev. 2012;20(3):118-129.
- Maureen M et al. Noninvasive Evaluation With Multislice Computed Tomography in Suspected Acute Coronary Syndrome: Plaque Morphology on Multislice Computed Tomography Versus Coronary Calcium Score. J Am Coll Cardiol. 2008 Jul, 52 (3) 216–222