Reviewed by a board-certified geriatrician
Many people have heard of a coronary artery calcium score, sometimes called a heart scan. It is a useful test, but it doesn't show everything going on in the heart's arteries. Here is what plaque is, the difference between "hard" and "soft" plaque, and what to ask your doctor.
How plaque builds up
Plaque forms when LDL ("bad") cholesterol slips into the wall of an artery and the body's repair cells gather around it. Over years this becomes a bump of fat, cells and scar tissue inside the artery wall. Our article on blood pressure and cholesterol explains this process in more detail.
Soft plaque and hard plaque
Soft (non-calcified) plaque is younger plaque. It has a fatty core under a thin cap and is often inflamed. If that cap tears, a blood clot can form on it and suddenly block the artery. This is how most heart attacks start.
Hard (calcified) plaque is plaque that has hardened with calcium over time, a bit like scar tissue that has healed. Dense calcium tends to make a plaque more stable [1].
Most people with plaque have a mix of both. Plaque can be present without causing any narrowing or symptoms.
What a calcium score shows
A calcium score is a quick CT scan with no dye. It counts the hard, calcified plaque in the heart's arteries. A higher score means more plaque overall and a higher chance of a heart attack, and this holds across racial and ethnic groups [2].
The score helps guide decisions about cholesterol medicine. In the 2018 U.S. cholesterol guideline, a score of zero in someone at moderate risk means it is reasonable to hold off on a statin, unless they have diabetes, smoke or have a strong family history. A score of 100 or more favors starting one [3].
Why a calcium score may not be enough
It can't see soft plaque. A calcium score only detects calcium. In a large study of people with chest symptoms and a score of zero, about 16% still had plaque on a CT angiogram, and 3.5% had a narrowing of 50% or more [4].
The riskiest plaque is often soft. On CT angiograms, plaques with a large fatty core and an outward-bulging wall were far more likely to cause a heart attack within about two years [5].
The score can rise on treatment. Statins help soft plaque firm up with calcium, so a calcium score may go up even when treatment is working [6]. A rising score on a statin isn't necessarily bad news.
A score of zero is still reassuring for most people without symptoms. It just isn't a guarantee, especially if you have symptoms or strong risk factors.
A test that shows soft plaque: CT angiography
A coronary CT angiogram (CCTA) uses dye through an IV to show the inside of the heart's arteries. It can see both soft and hard plaque, and how narrow the arteries are. Newer software can also measure how much plaque there is and what type, though this is still being studied.
In a large trial of about 4,100 people with stable chest pain, adding a CT angiogram to usual care led to fewer heart attacks and heart-related deaths over five years (2.3% vs 3.9%). This was likely because more people with plaque started preventive treatment [7].
CT angiography isn't a routine screening test for everyone, though. It uses contrast dye, which can be hard on the kidneys, plus some radiation, and it can find things that lead to more tests. For older adults especially, it is worth asking: will the result change what we do?
What to ask your doctor
Would a calcium score help me decide about cholesterol medicine?
I have a score of zero but still have symptoms or strong risk factors. Should we look further?
My score went up on a statin. What does that mean for me?
Is a CT angiogram worth it for me, given my kidneys, other health conditions and goals?
Don't start aspirin on your own because of a scan result. For people 60 and older without heart disease, the bleeding risk usually outweighs the benefit, so it is a decision to make with your doctor [8].
Keeping your arteries healthy
Whatever your score, the same steps slow plaque, help it stabilize and protect your arteries. The American Heart Association calls them Life's Essential 8 [9]:
Eat a heart-healthy diet with plenty of vegetables, fruit, beans, whole grains and fish, and less salt and processed food.
Stay active: about 150 minutes a week of moderate activity, such as brisk walking.
Don't smoke or vape.
Sleep 7 to 9 hours a night.
Keep a healthy weight.
Keep cholesterol in check, with medicine if needed.
Keep blood sugar in check.
Keep blood pressure in a healthy range.
Our article on blood pressure and cholesterol has practical tips, including foods like beets, barley and oats.
Gum health may matter too. See Gum health and your heart.
Call 911 for chest pain or pressure, shortness of breath, pain spreading to the arm, jaw or back, cold sweats or sudden weakness. Don't wait for a test.
This article is for general education and isn't a substitute for advice from your own doctor.
Sources
Criqui MH, et al. Calcium density of coronary artery plaque and risk of incident cardiovascular events. JAMA. 2014;311(3):271-278.
Detrano R, et al. Coronary calcium as a predictor of coronary events in four racial or ethnic groups (MESA). N Engl J Med. 2008;358(13):1336-1345.
Grundy SM, et al. 2018 AHA/ACC Guideline on the Management of Blood Cholesterol. Circulation. 2019;139(25):e1082-e1143. doi:10.1161/CIR.0000000000000625. Summary: ACC, primary prevention for those at intermediate risk.
Villines TC, et al. Prevalence and severity of coronary artery disease and adverse events among symptomatic patients with coronary artery calcification scores of zero (CONFIRM). J Am Coll Cardiol. 2011;58(24):2533-2540.
Motoyama S, et al. Computed tomographic angiography characteristics of atherosclerotic plaques subsequently resulting in acute coronary syndrome. J Am Coll Cardiol. 2009;54(1):49-57.
Puri R, et al. Impact of statins on serial coronary calcification during atheroma progression and regression. J Am Coll Cardiol. 2015;65(13):1273-1282.
SCOT-HEART Investigators (Newby DE, et al.). Coronary CT angiography and 5-year risk of myocardial infarction. N Engl J Med. 2018;379(10):924-933.
US Preventive Services Task Force. Aspirin use to prevent cardiovascular disease: recommendation statement. JAMA. 2022;327(16):1577-1584.
Lloyd-Jones DM, et al. Life's Essential 8: updating and enhancing the American Heart Association's construct of cardiovascular health. Circulation. 2022.