A heart scan is a noninvasive imaging test that takes detailed pictures of your heart and its blood vessels to look for signs of heart disease. The most common type people mean when they search “heart scan” is a coronary calcium scan, a quick CT scan that measures calcium buildup in your artery walls. But the term can also refer to several other imaging tests, each designed to answer a different clinical question.
Types of Heart Scans
The phrase “heart scan” covers a handful of distinct tests, and the one your doctor recommends depends on what they’re looking for.
- Coronary calcium scan. A CT scan that detects calcium deposits in the walls of your coronary arteries. Calcium buildup is a direct marker of plaque formation (atherosclerosis), so this scan helps estimate your risk of a future heart attack. It uses no contrast dye and takes only a few minutes.
- CT coronary angiography (CTA). A more detailed CT scan that uses contrast dye injected into a vein to produce high-resolution images of the arteries themselves. It can reveal both calcified and non-calcified plaque, as well as narrowed or blocked arteries. CTA is the better tool when doctors need to confirm or rule out significant blockages, not just estimate risk.
- Echocardiogram. Uses sound waves (ultrasound) rather than radiation to create moving images of the heart. It shows heart size, shape, and how well the muscle is pumping blood. This is the go-to test for evaluating valve problems, heart failure, and structural abnormalities.
A calcium scan and a CT angiogram might sound similar, but they answer different questions. In an occupational health study comparing the two approaches, about 12% of people cleared by a calcium scan alone turned out to have significant non-calcified plaque when they underwent a CT angiogram. In other words, a calcium scan is excellent for risk stratification, but a CT angiogram provides a more complete picture of what’s actually happening inside the arteries.
How a Coronary Calcium Scan Works
Because the coronary calcium scan is the most widely referenced “heart scan,” it’s worth understanding exactly what happens during one. The scan uses a standard CT machine to detect calcium deposits in your artery walls, then assigns a number called an Agatston score that reflects how much calcium was found.
The score breaks down into four risk tiers:
- 0: Very low risk. No detectable calcium.
- 1 to 99: Mildly increased risk. Some plaque is forming.
- 100 to 299: Moderately increased risk.
- 300 or higher: Moderate to severely increased risk.
A score of zero is particularly meaningful. A meta-analysis of over 92,000 patients with chest pain found that the absence of coronary calcium correlated with a very low prevalence of obstructive artery disease and a very low rate of major cardiac events in the years that followed. It’s not a guarantee (rare cases of significant blockage with a zero score do exist), but it’s one of the strongest “all clear” signals available in preventive cardiology.
Who Should Get One
Calcium scoring is most useful for people in a gray zone of cardiovascular risk, where the results could change the treatment plan. The American College of Cardiology and American Heart Association recommend considering a calcium scan for adults aged 40 to 75 whose cholesterol and other risk factors put them on the fence about starting preventive medication. For adults 76 to 80 without diabetes whose LDL cholesterol falls between 70 and 189 mg/dL, the same guidelines suggest it can help guide the decision. Beyond age 80, the test is generally reserved for case-by-case discussions.
If you already have confirmed heart disease or are already taking a statin, a calcium scan typically won’t change your management and isn’t recommended as a screening tool.
What the Scan Is Like
Preparation is minimal. Cleveland Clinic’s instructions ask patients to avoid food, drink, caffeine, and tobacco for four hours beforehand. You’ll also want to mention any medications you take, any allergies, and whether you could be pregnant.
At the appointment, you change into a gown and remove any jewelry near your chest. Sticky electrode patches go on your chest (and sometimes your arms or legs) so a monitor can track your heartbeat and time the scan to your heart’s rhythm. You lie on your back on a table that slides into a large, tube-shaped CT scanner. The actual imaging takes roughly 10 to 15 minutes. There are no needles and no contrast dye for a standard calcium scan. Most people describe the experience as uneventful.
Radiation Exposure
A coronary calcium scan does use X-ray radiation. The median dose is about 2.3 millisieverts (mSv), though it can range from under 1 mSv to over 10 mSv depending on the machine and protocol. For context, the average American absorbs roughly 3 mSv per year from natural background radiation, so a single calcium scan is roughly equivalent to about eight months of everyday exposure. One study estimated that if men were screened every five years from age 45 to 75 and women from 55 to 75, the excess lifetime cancer risk would be about 42 additional cases per 100,000 men and 62 per 100,000 women. The risk is real but small, which is why the test is targeted at people whose results are likely to change clinical decisions rather than offered to everyone.
Cost and Insurance
Here’s a common frustration: nearly all insurance payers, including Medicare, deny coverage for coronary calcium scans when used as a preventive screening tool. That means most people pay out of pocket. The good news is that many hospitals and imaging centers have dropped their prices to the $50 to $100 range, making it one of the more affordable imaging tests available. Call ahead and ask for the self-pay rate, because prices can vary significantly from one facility to the next.
What Happens After an Elevated Score
A positive calcium score doesn’t mean you need a stent or surgery. Current guidelines are clear that for people without symptoms, there’s no documented benefit from immediately jumping to stress testing or invasive angiography. Instead, the standard approach is lifestyle changes and aggressive cholesterol management.
That means a diet lower in saturated fat, regular physical activity, quitting smoking if applicable, and getting blood pressure and blood sugar under control. On the medication side, the ACC and AHA recommend statin therapy for patients aged 40 to 75 with a calcium score of 100 or higher, regardless of whether they have symptoms. For scores above 400, the cholesterol targets become more aggressive. Doctors typically recheck cholesterol levels within three months to confirm the treatment is working.
The core message of a high calcium score isn’t that you’re about to have a heart attack. It’s that plaque has been building silently and now is the time to intervene before symptoms develop.