Understanding your heart tests

What ECGs, troponin and cholesterol blood tests, echocardiograms, stress tests, heart CT scans and coronary angiograms show, how they feel and how to prepare.

6 min read · last reviewed September 28, 2026

Heart care comes with a lot of tests, and a lot of new words. Each test answers a different question: Is my heart's rhythm normal? Has the muscle been hurt? How well does it pump? Are my arteries narrowed? Knowing what to expect can make each one a little less stressful.

Here is a plain-language guide to the most common heart tests.

Electrocardiogram (ECG or EKG)

What it shows: The electrical activity of your heart. It shows how fast your heart beats, whether the rhythm is steady, and signs of strain or damage, such as from a heart attack.

What it feels like: Painless. You lie still while a nurse or technician places small sticky patches (electrodes) on your chest, arms and legs. It takes a few minutes. No electricity goes into your body. Some chest hair may need to be shaved so the patches stick.

How to prepare: Nothing special. Wear a top that is easy to take off.

Blood tests

Troponin. Troponin is a protein that leaks into the blood when heart muscle is hurt. It is one of the main tests for a heart attack. Levels can take a few hours to rise, so you will often have it checked more than once over several hours.

Cholesterol panel (lipid panel). This measures fats in your blood: LDL ("bad") cholesterol, HDL ("good") cholesterol, and triglycerides. Your LDL number helps your team decide on cholesterol-lowering treatment and track how well it is working.

Other blood tests may check blood sugar, kidney function, blood count and more.

What it feels like: A quick needle poke in the arm.

How to prepare: Usually nothing. For some cholesterol tests you may be asked to fast (no food or drink except water) for 9 to 12 hours. Ask if you need to.

Echocardiogram ("echo")

What it shows: Moving pictures of your heart made with sound waves (ultrasound). It shows the size and shape of your heart, how well it pumps, and how the valves work. After a heart attack, it can show whether part of the muscle is not moving as well.

What it feels like: Painless. You lie on your back or left side. A technician puts cool gel on your chest and moves a small wand over it. It usually takes less than an hour.

How to prepare: Usually nothing. A less common type, where the wand goes down the throat (called a TEE), needs fasting and a relaxing medicine. Your team will tell you if you need this.

Stress test

What it shows: How your heart works when it has to work hard. Some problems only show up when the heart is beating fast. A stress test may use an ECG alone, or add an echo or a nuclear scan to take pictures.

What it feels like: You walk on a treadmill or ride a stationary bike, going a little faster or harder every few minutes, for about 10 to 15 minutes. Your ECG and blood pressure are watched closely. If you can't exercise, you get a medicine through an IV that makes your heart work as if you were exercising. The team will stop the test if you have symptoms or get too tired.

How to prepare:

• Wear comfortable clothes and walking shoes.
• You may be asked to avoid coffee, tea, cola and other caffeine for a set time.
• You may be asked to skip certain medicines before the test. Only do this if your team tells you to.

Heart CT scans

A CT scanner uses X-rays and a computer to make detailed pictures. You lie on a table that slides into a large, open ring. There are two main heart CT scans.

Coronary calcium scan. This measures calcium in the walls of your heart arteries, a sign of plaque. It gives a "calcium score." A score of 0 is normal. Higher scores mean more plaque. It uses no dye and takes about 10 to 15 minutes.

CT coronary angiography (CTCA or CCTA). This uses a dye (contrast) injected into a vein to show the inside of your heart arteries and any narrowing. You may get a medicine to slow your heart rate so the pictures are clear. You may feel a brief warm flush or a metallic taste when the dye goes in. The scan itself is quick, but plan for an hour or more in total.

How to prepare:

• Tell the team if you have kidney problems, have had a reaction to X-ray dye, are or could be pregnant, or feel anxious in tight spaces.
• Follow any instructions about caffeine, food or medicines.

Coronary angiogram (cardiac catheterization)

What it shows: A detailed X-ray view of your heart arteries, showing exactly where and how much they are narrowed. If a blockage is found, it can often be treated at the same time with a balloon and a stent (called angioplasty or PCI).

What it feels like: It is done in a hospital. You are awake but given medicine to help you relax. The doctor numbs a spot on your wrist or groin and passes a thin, soft tube (catheter) through the artery to your heart. You should not feel the tube moving. Dye is injected, and you may feel a warm flush. Afterwards you may have a bruise and some soreness where the tube went in. You will rest for a few hours, and sometimes stay overnight.

How to prepare:

• You will usually be asked not to eat for a few hours before.
• Ask which medicines to take or hold that morning, especially blood thinners and diabetes medicines.
• Tell the team about allergies, kidney problems, or pregnancy.
• Arrange a ride home. You should not drive yourself.

Something you can do: Before any test, ask, "Do I need to do anything to get ready?" and write down the answer.

Questions to ask your care team

• Why do I need this test, and what question will it answer?
• Do I need to fast, avoid caffeine or change my medicines before it?
• How long will it take, and can someone come with me?
• Are there any risks for me, such as with the dye or radiation?
• When and how will I get my results?
• What do my results mean, and what happens next?

This article is general information, not medical advice. Talk with your health care team about your own situation. In an emergency, call 9-1-1 or your local emergency number.

In an emergency, call 9-1-1 or your local emergency number.

General information, not medical advice. It does not replace your own care team. If you think you or someone else is having a medical emergency, call 9-1-1 or your local emergency number. If you are in crisis or thinking about suicide, call or text 9-8-8 (Canada and the US).

Back to Heart disease