Most people with plaque buildup in their arteries have no symptoms at all until the blockage becomes severe. Arteries can narrow significantly before you feel anything, which is why screening tests matter far more than waiting for warning signs. The good news is that several reliable tests can detect plaque at different stages, from early calcium deposits to advanced blockages.
Why You Probably Won’t Feel It Early On
Plaque buildup, known medically as atherosclerosis, is a slow process that typically takes years or decades. Mild atherosclerosis causes no symptoms. You won’t feel plaque forming on artery walls, and your body compensates well enough that blood flow stays adequate for a long time. Symptoms only appear once an artery is so narrowed or clogged that it can’t deliver enough blood to the organ it supplies.
When symptoms do show up, they depend on which arteries are affected:
- Heart arteries: Chest pain or pressure during exertion, sometimes called angina
- Brain arteries: Sudden numbness or weakness in an arm or leg, slurred speech, temporary vision loss in one eye, or facial drooping (signs of a mini-stroke)
- Leg arteries: Pain or cramping in your legs when walking that eases when you stop
- Kidney arteries: High blood pressure that’s hard to control, or declining kidney function
If you’re experiencing any of these, plaque has likely been building for years. That’s why the real answer to “how do I know?” isn’t about symptoms. It’s about testing.
The Coronary Calcium Score
A coronary artery calcium (CAC) scan is the most direct, accessible way to find out whether plaque exists in your heart arteries. It’s a quick, low-dose CT scan of your chest that takes about 10 minutes, requires no injections or preparation, and costs between $75 and $300 at most imaging centers (often not covered by insurance, but relatively affordable out of pocket).
The scan detects hardened, calcified plaque in your coronary arteries and produces a number called the Agatston score. Here’s what the ranges mean:
- 0: No detectable calcified plaque. Very low risk.
- 1 to 99: Mildly increased risk. Some plaque is present.
- 100 to 299: Moderately increased risk. Significant plaque buildup.
- 300 or higher: Moderate to severe risk. Substantial plaque burden.
- Over 1,000: A distinct very high-risk category, associated with much greater risk of heart events, and identified separately on score reports.
A score of zero is reassuring but not a lifetime guarantee. It means calcified plaque hasn’t formed yet. One important limitation: this scan only detects calcified (hardened) plaque. It cannot see soft, fatty plaque that hasn’t yet calcified.
CT Angiography for a More Complete Picture
Coronary CT angiography (CCTA) goes a step further. While a calcium score only shows hardened deposits, CCTA uses contrast dye injected into a vein to visualize both calcified and non-calcified plaque, plus how much the artery has actually narrowed. This makes it particularly useful if your doctor suspects blockages but your calcium score is low, since fatty plaque that hasn’t hardened yet won’t appear on a standard calcium scan.
CCTA is more expensive than a calcium score and involves contrast dye and a higher radiation dose, so it’s typically reserved for people with symptoms or intermediate risk rather than routine screening. But for identifying the full picture of plaque in coronary arteries, it’s currently the most detailed non-invasive option available.
Stress Tests and Their Limits
Stress tests are commonly ordered when chest pain or shortness of breath raises concern about blocked heart arteries. You exercise on a treadmill (or receive a medication that mimics exercise) while your heart is monitored for signs that parts of the muscle aren’t getting enough blood.
A basic exercise treadmill test without imaging has a sensitivity of only about 70% for detecting significant blockages. That means roughly 3 out of 10 people with real coronary artery disease will get a normal result. Adding imaging to the stress test, either with a nuclear tracer or ultrasound of the heart, pushes sensitivity up to 80 to 90%, with specificity around 70 to 80%.
Stress tests are better at detecting arteries that are already severely narrowed (typically 70% or more blocked) than catching earlier-stage disease. They tell you whether blood flow is compromised right now, not how much plaque is sitting on artery walls. A normal stress test does not mean your arteries are clean.
Checking for Plaque in Your Legs
If leg pain during walking is a concern, or if you have risk factors like diabetes and smoking, a simple test called the ankle-brachial index (ABI) can check for plaque in leg arteries. A technician measures blood pressure in both arms and both ankles using a standard cuff and a handheld ultrasound device. The ratio of ankle pressure to arm pressure tells the story:
- 1.0 to 1.4: Normal. No significant blockage.
- 0.90 to 0.99: Borderline. Arteries may be starting to narrow.
- Below 0.90: Peripheral artery disease is present.
The test takes about 15 minutes, is painless, and can be done in a regular office visit. Finding peripheral artery disease in the legs also signals that plaque is likely present elsewhere in the body, including the heart and brain arteries.
Carotid Ultrasound for Neck Arteries
An ultrasound of the carotid arteries in your neck can measure the thickness of the artery wall lining and directly visualize plaque deposits. The measurement, called intima-media thickness, is a well-established marker for atherosclerosis throughout the body. The ultrasound can also characterize the plaque itself: its density, surface texture, and whether it shows signs of ulceration, all of which help predict the risk of a future stroke. This test involves no radiation, no needles, and takes about 30 minutes.
What Blood Tests Can and Can’t Tell You
No blood test can confirm plaque is in your arteries. But certain markers help estimate your risk and can flag the kind of inflammation that drives plaque formation.
Standard cholesterol panels measure LDL (“bad” cholesterol), the primary material that infiltrates artery walls and forms plaque. High LDL is the single strongest blood-based predictor of atherosclerosis risk. But some people develop significant plaque with only modestly elevated cholesterol, which is where other markers help fill in the picture.
High-sensitivity C-reactive protein (hs-CRP) measures inflammation in the body. People with non-calcified, softer plaque tend to have notably higher hs-CRP levels than people with no plaque or only calcified plaque. In one study of over 300 patients, those with exclusively soft plaque had median hs-CRP levels more than double those of plaque-free individuals. Elevated hs-CRP in the context of other risk factors can push the decision toward imaging.
Lipoprotein(a), often written as Lp(a), is a genetically determined particle that promotes plaque formation through several pathways: it increases inflammation in blood vessel walls, encourages immune cells to accumulate in arteries, and deposits directly onto artery walls. Unlike regular LDL cholesterol, Lp(a) levels are largely set by your genes and don’t respond much to diet or standard cholesterol medications. About 20% of people have elevated Lp(a). If yours is high, it means your arteries are under additional plaque-building pressure even if your standard cholesterol numbers look fine. It only needs to be tested once in your lifetime since levels rarely change.
Who Should Get Screened
Calcium scoring is most useful for people at intermediate cardiovascular risk, meaning you have some risk factors (high blood pressure, family history of early heart disease, elevated cholesterol, or a long smoking history) but haven’t had a heart attack or been diagnosed with heart disease. If your risk is clearly low (young, no risk factors), screening is unlikely to change your care. If your risk is clearly high (established heart disease, diabetes with multiple risk factors), you’ll already be treated aggressively, and a calcium score won’t add much.
The sweet spot is the large group of people in between, where a calcium score of zero might reassure you enough to hold off on medication, and a score of 200 might motivate you and your doctor to act more aggressively on cholesterol, blood pressure, and lifestyle changes. For people with a family history of heart attacks before age 55 in men or 65 in women, screening earlier (in your 40s or even late 30s) is reasonable regardless of other risk factors.