The five heart tests people hear about most are not interchangeable. An ECG reads the heart's electrical rhythm. An echocardiogram shows its structure and pumping. A stress test checks blood flow under effort. A calcium score measures calcified plaque. A CT angiogram maps the arteries themselves.
Which one fits depends mostly on whether you have symptoms. Four of the five are mainly used to work out the cause of a symptom. Only the calcium score is aimed at people who feel well and want a clearer view of their long-term risk.
Key takeaways
- An ECG, an echo and a stress test show how the heart is working today, not how much plaque you carry.
- A calcium score and a CT angiogram both look at the arteries, but only the angiogram shows soft plaque and narrowing.
- Screening people who feel well with an ECG or an echo has not been shown to prevent heart attacks.
- Symptoms such as chest discomfort or breathlessness call for a medical evaluation, not a screening scan.
- Of these five tests, the calcium score is the only one that is part of a Cardio Res-Q assessment.
The five tests at a glance
| Test | Question it answers | Mainly used for |
|---|---|---|
| ECG (electrocardiogram) | Is the heart's electrical rhythm normal, and are there signs of strain or damage? | Chest pain, palpitations, fainting |
| Echocardiogram (echo) | How well do the heart muscle and valves work? | Breathlessness, murmurs, suspected heart failure or valve disease |
| Stress test | Does the heart muscle get enough blood when it works hard? | Symptoms on exertion that may come from a narrowed artery |
| Calcium score (CAC) | Is there calcified plaque in the heart arteries, and how much? | Adults without symptoms whose risk is uncertain |
| CT angiogram (CTA) | Is there plaque of any type, and is an artery narrowed? | Stable chest pain that needs a diagnosis |
ECG and echocardiogram: how the heart is working
ECG. A resting ECG records the heart's electrical activity through stickers on the chest, arms and legs. It takes a few minutes and uses no radiation. It can show a rhythm problem, a heart attack in progress, or signs of an older one.
It cannot see plaque, and it is often normal in people who have plenty, which is one reason heart disease can stay silent.
As a screening test it has a weak record. The US Preventive Services Task Force advises against ECG screening, resting or exercise, for adults with no symptoms and a low risk of cardiovascular disease.1 For people at higher risk, it found too little evidence to say either way.
Echocardiogram. An echo is an ultrasound of the heart. It shows the size of the chambers, how strongly the muscle squeezes and whether the valves work properly. There is no radiation. It is a key test when heart failure or valve disease is suspected. It does not show the coronary arteries, so it cannot tell you whether you have plaque.
It has also been tested as a screening tool. In a Norwegian trial, 6,861 middle-aged adults were randomly assigned to echo screening or no screening and followed for 15 years. Deaths, heart attacks and strokes were no lower in the screened group.2
Stress test: blood flow under effort
A stress test watches the heart while it works hard, on a treadmill or with a medicine that mimics exercise. It looks for a part of the heart muscle that runs short of blood, which usually happens only when an artery is tightly narrowed.
That makes it a test for symptoms, not a plaque detector. Plaque that does not yet limit flow will not show. Our comparison of the calcium score and the stress test covers this in detail.
Calcium score and CT angiogram: looking at the arteries
Calcium score. A calcium scan is a quick CT of the heart with no injection. It measures calcium in the walls of the coronary arteries, which stands in for the total amount of plaque built up over the years. With careful technique the radiation dose averages about 1 to 1.5 mSv.3
It is the one test on this list designed for people who feel well. Its blind spot is plaque that has not calcified. Score bands and who the scan helps are covered in our guide to the coronary calcium score.
CT angiogram. A CT angiogram uses the same kind of scanner, but with contrast dye injected into a vein. The dye lights up the inside of the arteries, so the scan shows both soft and calcified plaque and how much any plaque narrows the channel.
Its best evidence is in people with symptoms. In a Scottish trial of 4,146 patients with stable chest pain, adding CT angiography to standard care lowered the five-year rate of coronary death or nonfatal heart attack from 3.9% to 2.3%.4
It asks more of you than a calcium scan, including an IV line and contrast dye. It is a diagnostic test that a clinician orders to answer a specific question.
Which test fits which situation
If you have symptoms, none of this is a do-it-yourself decision. Sudden or severe chest pain, breathlessness or fainting means calling 911. For symptoms that come and go, see a clinician. US chest pain guidance matches the test to a person's symptoms and risk and recommends that the choice be a shared decision.5
If you feel well, the starting point is a risk estimate and blood work, not a stress test or an echo. When the picture is still unclear, a calcium score can help. Be aware that the US Preventive Services Task Force judged the evidence insufficient to say whether adding a calcium score to standard risk assessment improves outcomes.6 It is most useful when the result would change a decision.
Your next step: where the calcium score fits at our clinic
Cardio Res-Q is a prevention program. Its Comprehensive Assessment ($775) is built on a clinical evaluation and advanced blood tests. The Enhanced Assessment ($999) adds a CIMT ultrasound and a calcium score. The calcium scan is ordered by your provider and done at an outside imaging facility, as a separate self-pay study that typically costs $100 to $200.
ECGs, echocardiograms, stress tests and CT angiograms are not part of either assessment. Those belong with your cardiologist or primary care doctor, and we are happy to share results with them. Cardio Res-Q is not emergency care.
To see how the two options differ, read Comprehensive vs. Enhanced Assessment, or go to the Cardio Res-Q program page.
Are You a Candidate for Cardio Res-Q?
Three quick questions about the risk factors we screen for. Your answers stay between you and the clinic.
Frequently asked questions
Which heart test is the most accurate?
There is no single winner, because each test measures something different. An ECG is the right tool for rhythm, an echo for pumping and valves, a stress test for blood flow under effort, and CT scans for plaque. The useful question is which test answers your specific question.
Can an ECG or an echo show blocked arteries?
Not directly. Neither test images the coronary arteries. They can show the effects of a blockage, such as an abnormal rhythm, a past heart attack or a weak area of muscle, but both can be normal when plaque is present.
Do I need all five tests to be safe?
No. More testing is not automatically better. Tests done without a clear reason can produce false alarms and lead to further procedures. The right set depends on your symptoms, your risk and what the result would change.
Related reading
This article is for general education and is not medical advice. Decisions about testing and medication should be made with your clinician. If you have chest pain or other symptoms of a heart attack, call 911.
