Echo, ECG, calcium score and CTCA get used interchangeably in conversation, but they're four different tests that look at four different things. An ECG checks the heart's electrical rhythm. An echo (echocardiogram) looks at its structure and pumping function. A calcium score measures plaque build-up in the coronary arteries. A CTCA produces a detailed picture of the arteries themselves. Knowing which is which makes it much easier to understand what your doctor is actually asking for, or which one might be worth discussing.
What is an ECG (electrocardiogram)?
An ECG (sometimes written EKG) records the electrical signals that make the heart beat. Small electrode stickers are placed on the chest, arms and legs, and the reading takes a few minutes while lying still. It's quick, painless and produces an immediate result.
An ECG is good at picking up patterns linked to irregular heart rhythms (arrhythmias), and it can also flag findings suggestive of a past heart attack, reduced blood flow to the heart muscle, or an enlarged heart chamber wall, all of which a doctor may want to follow up. It's a snapshot of electrical activity at that moment, so it does not show the structure of the heart or the condition of the coronary arteries.
What is an echocardiogram (echo)?
An echocardiogram, usually just called an echo, is an ultrasound of the heart. A technician moves a probe over the chest to produce moving images of the heart's chambers and valves, and how well the heart is pumping blood with each beat.
An echo is used to look at heart structure and function, things like valve movement, chamber size and pumping efficiency. It uses sound waves rather than radiation. Like an ECG, an echo does not directly show the coronary arteries, which is where plaque and narrowing linked to heart attacks tend to build up.
What is a coronary calcium score?
A coronary calcium score is a low-dose CT scan that measures the amount of calcium, a marker of plaque, sitting in the walls of the coronary arteries. It doesn't use contrast dye, takes only a few minutes, and produces a single score that reflects the overall calcium build-up detected.
A higher score is generally linked to a higher burden of plaque and cardiovascular risk, which is why it's most often used as a screening tool for people with moderate risk factors such as high cholesterol, high blood pressure, a family history of heart disease, or an age and lifestyle profile their doctor considers relevant. It tends to add the least useful information at the low and high ends of risk, including in people under 40, where calcified plaque is uncommon regardless of underlying risk.
It's also worth knowing that a score of zero doesn't rule out coronary artery disease. Some plaque is soft rather than calcified, and a calcium score only measures the calcified kind, so a small proportion of people with a zero score can still have narrowing that a calcium score won't pick up. The result is a number to take to your doctor as part of a broader risk conversation, not a diagnosis on its own.
The Coronary Calcium Score test on i-screen includes a pre-screen clinician consult, an online referral and the CT scan itself, so no separate GP visit is needed to get started.
What is a CTCA (CT coronary angiogram)?
A CTCA is also a CT scan of the heart, but it uses an injected contrast dye to produce detailed images of the coronary arteries themselves, not just the calcium sitting in the artery walls. This means it can also pick up soft, non-calcified plaque that a calcium score can miss, and can show where the arteries have narrowed.
Because it involves contrast dye and a higher radiation dose than a calcium score (modern scans are typically under 6 mSv), a CTCA is generally arranged through a GP or cardiologist, who will consider whether it's the right next step, sometimes after an ECG, echo or calcium score has already raised a question worth looking into further, including a zero calcium score alongside symptoms or other risk factors that don't add up.
Echo vs ECG vs calcium score vs CTCA at a glance
| Test | What it looks at | How it's done | Uses radiation? | | --- | --- | --- | --- | | ECG | Electrical rhythm of the heart | Electrode stickers on chest and limbs, a few minutes | No | | Echo | Heart structure and pumping function | Ultrasound probe on the chest | No | | Calcium score | Calcium build-up in the coronary artery walls | Low-dose CT scan, no contrast dye | Yes (low dose) | | CTCA | Detailed images of the coronary arteries, including narrowing | CT scan with contrast dye | Yes |
Which test might be right for you?
That depends on what your doctor is trying to work out, and it's a conversation worth having with them rather than choosing between tests on your own.
As a general guide: an ECG is often the first check when something about heart rhythm needs a look, an echo is used when structure or pumping function is the question, and a calcium score is more often used for longer-term risk assessment in people without current symptoms but with risk factors worth understanding. A CTCA tends to come later, when a more detailed look at the arteries is needed.
A Precision Cardiovascular Blueprint from i-screen combines several of these angles in one panel, an ECG alongside a coronary calcium score, cardiac biomarkers, advanced lipids and genetic risk markers, reviewed with a specialist teleconsult.
If you'd rather start with blood markers before moving to imaging, the Cardiovascular Health Test looks at lipoproteins, cholesterol, inflammation and blood glucose together as an early picture of cardiac risk.
Do you need a GP referral?
It depends on the test. A coronary calcium score booked through i-screen includes its own clinician consult and online referral, so a separate GP visit isn't required to get started. A CTCA is a more involved scan and is generally arranged through a GP or cardiologist, who will factor in your history and any earlier results before referring you.
For a broader look at where cardiac risk markers fit alongside these imaging tests, the Heart & Cardiovascular Health hub covers the full range of options.
This information is not intended to be a substitute for professional medical advice. Always seek the guidance of your doctor or other qualified health professional with any questions you may have regarding your health or a medical condition. i-screen provides wellness and educational services only. Our services do not diagnose, treat, cure, or prevent any disease or medical condition.
