There are several ways to check for plaque in your arteries, ranging from simple blood tests to specialized imaging scans. The right approach depends on your age, risk factors, and whether you already have symptoms. No single test catches everything, because arterial plaque comes in different forms and affects different parts of the body. Here’s what each option measures and who it’s best suited for.
Coronary Calcium Score: The Most Common Starting Point
A coronary artery calcium (CAC) scan is the most widely used test for directly detecting plaque in the heart’s arteries. It’s a quick, non-contrast CT scan that takes about 10 minutes and measures the amount of hardened (calcified) plaque in your coronary arteries. The result is a number called an Agatston score.
A score of zero means no calcified plaque is visible, which suggests a low chance of heart attack in the coming years. A score between 100 and 300 indicates moderate plaque deposits and a relatively high risk of heart attack or other cardiovascular events within the next three to five years. A score above 300 signals more extensive disease and higher risk. Scores between 1 and 99 fall in a mild category that still warrants attention.
The 2019 guidelines from the American Heart Association and American College of Cardiology position this scan as a decision-making tool for people at intermediate risk, meaning a 7.5% to 20% estimated chance of a cardiovascular event over 10 years. It can also be useful for people at borderline risk (5% to 7.5%) or even lower-risk adults who have a strong family history of early heart disease. It’s not intended as a blanket screening test for everyone. Rather, it helps you and your doctor decide whether preventive treatment like a statin is worth starting.
One important limitation: a calcium score only detects hardened plaque. It misses softer, non-calcified plaque, which can be just as dangerous.
CT Angiography: Seeing Inside the Artery Wall
Coronary computed tomography angiography (CCTA) goes a step further than a calcium score. It uses contrast dye injected into a vein to produce detailed images of the coronary arteries, showing not just calcified plaque but also the softer, fatty deposits that a calcium scan misses. This matters because non-calcified plaque is often the type that ruptures and triggers a heart attack.
CCTA classifies plaque by density. The densest material (above 350 Hounsfield units on the scan) represents calcified plaque. Lower-density material in the range of roughly 130 to 350 units corresponds to fibrous plaque. The lowest-density deposits, below about 75 units, represent fatty plaque that tends to be less stable. Doctors typically order a CCTA when symptoms like chest pain need further investigation, or when a calcium score alone doesn’t tell the full story. It’s more expensive and involves radiation and contrast dye, so it’s usually reserved for situations where the added detail changes the treatment plan.
Carotid Ultrasound: Checking the Neck Arteries
Not all arterial plaque lives in the heart. The carotid arteries in your neck carry blood to your brain, and plaque buildup there increases the risk of stroke. A carotid intima-media thickness (CIMT) test uses ultrasound to measure the thickness of the two innermost layers of the carotid artery wall. Thickening in these layers can signal early atherosclerosis, sometimes before you have any symptoms at all.
The test is painless, takes about 15 to 30 minutes, and doesn’t involve radiation. It’s particularly useful as an early warning system. Your doctor uses the measurement alongside other risk factors to build a more complete picture. However, CIMT has fallen somewhat out of favor for routine screening because its ability to predict events beyond what standard risk calculators already capture has been debated. It remains a helpful tool in certain clinical situations, especially when other test results are inconclusive.
Ankle-Brachial Index: Testing for Leg Artery Blockages
If plaque builds up in the arteries of your legs, it causes peripheral artery disease (PAD), which can lead to pain when walking, slow-healing wounds, and increased risk of heart attack and stroke. The ankle-brachial index (ABI) is a simple, in-office test that compares the blood pressure in your ankle to the blood pressure in your arm.
A normal ratio falls between 1.11 and 1.40. Values between 0.91 and 1.00 are considered borderline. A ratio of 0.90 or below confirms PAD. On the other end, a reading of 1.40 or higher can indicate stiff, calcified arteries, which is itself a sign of cardiovascular risk. A reading below 0.80 is generally enough to diagnose PAD with confidence, while values between 0.80 and 1.00 often need repeat testing for a definitive answer.
This test is especially relevant for people over 50 with diabetes, smokers, and anyone who experiences leg pain or cramping during physical activity that resolves with rest.
Blood Tests That Reveal Hidden Risk
Imaging tests show plaque that already exists. Blood tests can reveal the biological conditions driving plaque formation, sometimes years before it shows up on a scan.
Apolipoprotein B
Standard cholesterol panels measure how much cholesterol your blood carries, but apolipoprotein B (ApoB) counts the actual number of particles capable of depositing cholesterol into artery walls. It’s a more direct measure of the traffic delivering plaque-building material. An ApoB level above 130 mg/dL puts you at higher risk for cardiovascular disease. Some cardiology guidelines set even stricter targets of less than 65 to 80 mg/dL for people between 40 and 75 who are on statin therapy.
Lipoprotein(a)
Lipoprotein(a), often written as Lp(a), is a genetically determined particle that promotes both plaque growth and blood clotting. Unlike regular cholesterol, your Lp(a) level is largely set by your genes and doesn’t change much with diet or exercise. A level of 125 nmol/L or higher increases your risk of heart attack and stroke. At 250 nmol/L or higher, that risk roughly doubles. Because the number stays stable over your lifetime, current guidelines recommend every adult get tested at least once. If your level is elevated, your doctor may pursue more aggressive management of other risk factors you can control.
High-Sensitivity C-Reactive Protein
This blood test measures inflammation throughout your body, which plays a central role in plaque formation and rupture. Results are reported in milligrams per liter. A level below 1 mg/L is considered low risk, 1 to 3 is intermediate, and 3 or above is high. Elevated levels don’t pinpoint where the inflammation is happening, so this test works best in combination with other assessments. A high reading alongside borderline cholesterol numbers, for example, might tip the decision toward starting treatment.
Which Tests Make Sense for You
If you have no symptoms and just want to understand your baseline risk, the most practical starting combination is a standard lipid panel, an ApoB measurement, a one-time Lp(a) test, and possibly a coronary calcium score if your estimated risk falls in the borderline or intermediate range. These tests are relatively affordable and widely available.
If you’re experiencing symptoms like chest tightness, shortness of breath during exertion, or leg pain when walking, your doctor will likely move to more targeted testing: a CCTA for coronary symptoms, an ABI for leg symptoms, or a carotid ultrasound if stroke risk is the concern. Stress tests, where your heart is monitored during exercise or medication-induced exertion, are another common step for evaluating whether existing plaque is actually restricting blood flow.
Keep in mind that plaque develops silently over decades. Many people with significant buildup feel completely fine until a blockage becomes severe or a plaque ruptures. The value of checking early is that you get the chance to slow or stop progression through lifestyle changes and, when needed, medication, long before a crisis forces the issue.