Several tests can detect clogged arteries, and the right one depends on where the blockage might be and how severe your symptoms are. For heart arteries specifically, the most common starting points are a coronary calcium scan, a CT angiogram, or a stress test. For arteries in the neck or legs, simpler tools like ultrasound or blood pressure comparisons between your arm and ankle can flag problems. Here’s how each test works, what it measures, and what the results actually mean.
Coronary Calcium Scan
A coronary artery calcium (CAC) scan is one of the simplest ways to check for plaque buildup in your heart’s arteries. It’s a quick, non-invasive CT scan that takes about 10 minutes and requires no preparation, no injections, and no exercise. The scan detects calcium deposits embedded in arterial plaque, which is a reliable marker that atherosclerosis (hardening of the arteries) is present.
Your result comes as an Agatston score, which falls into one of four categories:
- 0: Very low risk, no detectable calcium
- 1 to 99: Mildly increased risk, some plaque present
- 100 to 299: Moderately increased risk
- 300 or higher: Moderate to severely increased risk
A score of zero is reassuring but doesn’t completely rule out soft, non-calcified plaque. Still, it means your risk of a heart event in the next several years is very low. This test is most useful for people at intermediate risk who don’t yet have symptoms. It helps clarify whether aggressive prevention (like starting a statin) is worth it. Insurance coverage varies, so expect to pay out of pocket in some cases, typically $100 to $300.
CT Coronary Angiography (CCTA)
If your doctor wants a detailed picture of the arteries themselves, not just calcium, a CT coronary angiography is the go-to non-invasive option. This scan uses contrast dye injected through an IV to produce high-resolution images of your coronary arteries, showing both calcified and soft plaque, plus the degree of narrowing.
CCTA is highly accurate. For blockages that narrow an artery by 50% or more, it catches about 94% of cases. Its specificity, meaning its ability to correctly identify people without significant blockage, sits around 77%. The American Heart Association and American College of Cardiology guidelines recommend CCTA as a preferred first test for people under 65 with stable chest pain and no known heart disease, partly because it can also rule out blockages quickly and avoid the need for more invasive procedures.
The scan itself takes 15 to 30 minutes. You’ll need to avoid caffeine beforehand, and you may receive medication to slow your heart rate so the images come out sharp. There’s a small amount of radiation involved, comparable to a few years of natural background exposure.
Stress Tests
Stress tests don’t photograph your arteries directly. Instead, they reveal whether your heart is getting enough blood flow when it’s working hard. A blockage that seems minor at rest can starve the heart muscle of oxygen during exertion, and that’s what these tests are designed to catch.
There are three main types. The basic exercise stress test has you walk on a treadmill or pedal a stationary bike while monitors track your heart rhythm, blood pressure, and oxygen levels. It’s the simplest and cheapest option, and current guidelines consider it reasonable for low-risk people with stable chest pain. A stress echocardiogram adds ultrasound imaging before and after exercise, letting doctors see how well your heart muscle is pumping and whether any segments struggle under stress. This is often used when a basic stress test gives unclear results.
A nuclear stress test goes a step further. A small amount of radioactive tracer is injected into your bloodstream, and a specialized camera takes images of blood flow through your heart at rest and after exertion. Areas that light up normally at rest but show reduced blood flow during stress typically indicate a blockage. For people 65 and older, stress testing may be preferred over CCTA because older patients have a higher likelihood of blockages that cause real blood flow problems, making functional tests more informative than anatomy-only scans.
Preparation for nuclear stress tests usually means avoiding caffeine the day before and the day of the test, and possibly fasting for several hours. If you can’t exercise, medication can simulate the effect of exertion on your heart. The entire process takes two to four hours because images are captured at two separate time points.
Invasive Coronary Angiogram
The coronary angiogram, sometimes called a cardiac catheterization, is the gold standard for identifying and measuring arterial blockages. A thin catheter is threaded through an artery in your wrist or groin up to the heart, and contrast dye is injected directly into the coronary arteries while X-ray video captures the flow in real time. This gives the most precise view of where blockages are and how severe they are.
The procedure typically takes about an hour, though it can run longer if treatment happens at the same time. If a significant blockage is found during the angiogram, doctors can often place a stent right then to open the artery. Some people go home the same day; others stay overnight depending on results and whether any intervention was performed. Recovery from the catheter insertion site usually takes a few days, with instructions to avoid heavy lifting.
Because it’s invasive and carries a small risk of complications, an angiogram is generally reserved for cases where non-invasive tests have already suggested a significant problem, or when symptoms are severe enough to warrant immediate evaluation.
Tests for Arteries Outside the Heart
Clogged arteries aren’t limited to the heart. Blockages in the neck (carotid arteries) and legs (peripheral arteries) are common and have their own screening tools.
Carotid Ultrasound
This painless test uses sound waves to measure the thickness of the inner walls of the carotid arteries in your neck. A normal wall thickness is roughly 0.7 to 0.8 millimeters. When that measurement reaches 1 millimeter or above, it signals atherosclerosis and a meaningfully higher risk of stroke and cardiovascular disease. The test can also detect plaques directly and estimate how much they’re narrowing the artery. It takes about 15 to 30 minutes, requires no preparation, and involves no radiation.
Ankle-Brachial Index
The ankle-brachial index (ABI) is one of the simplest vascular tests available. A blood pressure cuff is placed on your arm and your ankle, and the two readings are compared as a ratio. Healthy arteries deliver similar pressure to both locations, producing a ratio between 1.00 and 1.40. A ratio of 0.91 to 0.99 is borderline, 0.41 to 0.90 indicates mild to moderate peripheral artery disease, and anything at or below 0.40 signals severe blockage. This test is quick, painless, and often done in a regular office visit for people with leg pain during walking, slow-healing foot wounds, or risk factors like diabetes and smoking.
Blood Tests That Flag Risk
No blood test can directly see a clogged artery, but some markers help estimate how much trouble is brewing. High-sensitivity C-reactive protein (hs-CRP) measures inflammation in your blood vessels, which drives plaque formation and instability. Levels below 1 mg/L are considered low risk, 1 to 3 mg/L moderate risk, and above 3 mg/L high risk. People with levels in the 5 to 20 mg/L range face the highest cardiovascular danger. When combined with cholesterol numbers, hs-CRP helps doctors decide how aggressively to treat.
Standard lipid panels measuring LDL cholesterol, HDL cholesterol, and triglycerides remain essential baseline tests. They don’t show existing blockages, but persistently high LDL is the primary driver of plaque buildup, making it a critical data point for prevention. The best outcomes in studies have been seen in patients who get both their LDL below 70 mg/dL and their CRP below 2 mg/L.
How Doctors Decide Which Test You Need
The choice of test depends largely on your symptoms, age, and baseline risk. If you have no symptoms but want to know your risk, a coronary calcium scan gives a quick, affordable answer. If you’re experiencing chest pain or shortness of breath, current guidelines point toward CCTA for younger patients and stress testing for those 65 and older. If non-invasive tests suggest a serious blockage, or if symptoms are worsening rapidly, an invasive angiogram is the next step because it can confirm the problem and fix it in one session.
For leg symptoms like cramping during walking or numbness, an ABI is the logical starting point. For stroke risk assessment, a carotid ultrasound provides direct visualization of neck artery health. In many cases, doctors use a combination of tests, starting with something simple and escalating only if the initial results raise concern.