Heart Disease and MRI Testing

Medically Reviewed by James Beckerman, MD, FACC on March 07, 2021

One test that looks for heart disease is called an MRI (magnetic resonance imaging). It uses large magnets and radio waves to make pictures of your body's internal organs. You’re not exposed to X-rays. This can also make images of your heart’s pumping cycle.

Why Do I Need It?

Your doctor uses MRIs to see how well different organs work, like your heart, lungs, major blood vessels, and pericardium (that’s the outside lining of your heart). It’s also used to see if you have things like:

How Should I Prepare?

If you are claustrophobic, meaning you have a fear of confined places, you may want to ask your doctor to give you a medication called a sedative to help you relax before your MRI. If you take a sedative, you should not eat any solid food for 6 hours before you take it to avoid nausea. You may have clear liquids like apple juice, Jell-O, black coffee, tea, or water up to 2 hours before you’re sedated.

You can take your regular medications (with sips of water) unless your doctor thinks you shouldn’t. Bring someone to drive you home from the procedure, since you’ll probably still be drowsy from the sedative.

If you aren’t claustrophobic, you won’t need sedation before the MRI scan. Eat as usual and take your medication as usual.

Since the MRI uses magnets, you shouldn’t have any metallic or magnetic items with you. Make sure to tell the staff if you have any implants made of metal or any of it under your skin. Some metallic implants, like sternal wires and clips used for heart surgery, don’t cause any issues.

Some conditions may make an MRI risky. Tell your doctor if you have:

  • An implanted pacemaker or defibrillator
  • An older model Starr-Edwards (metallic ball/cage type) heart valve implant
  • A cerebral aneurysm clip (a metal clip in a blood vessel in the brain)
  • An implanted insulin pump, narcotic pump, or implanted nerve stimulators (TENS) for back pain
  • Metal in your eye or eye socket
  • A cochlear implant for hearing problems

Also be sure to tell them if you’re pregnant.

You should wear:

  • Tops, including bras, that can come off easily before the MRI.
  • Metal-free pants, such as sweatpants with elastic bands.

A gown will be provided.

You should not wear or carry:

  • Belt buckles
  • Metal zippers
  • Snaps
  • Watches
  • Wallets with bank or credit cards with magnetic strips

What Happens?

You’ll change into a hospital gown. Then, the technician will place small, sticky electrode patches on your chest and back. Men may have their chest partially shaved to help the electrodes stick. They’re attached to an electrocardiograph (ECG) monitor that charts your heart's electrical activity during the test.

An intravenous (IV) line will probably be put into a vein in your arm to inject a non-iodine based dye. Your doctor may call this “contrast material.” It makes your organs more visible in the pictures that’ll be taken. Most people aren’t allergic or sensitive to this dye.

The MRI scanner unit is a long tube that scans your body as you lie on a platform bed inside it. It’s fully lit, ventilated, and it’s open at both ends. An intercom system allows you to talk to the operators during the test.

You’ll lie on your back on the scanner bed, with your head and legs elevated to make you comfortable. They’ll ask you to lie as still as possible. Every once in a while, they’ll need you to hold your breath for short periods to reduce blurring of the images from breathing.

During scanning, the equipment may create loud banging noises, which can be muffled with headphones or earplugs you’ll get before the scan starts.

It all takes between 30 and 75 minutes, depending on how many images are needed.

What’s Next?

Your doctor will discuss the results of your MRI scan with you.

If you were sedated, your doctor will let you know when you can eat, drink, and return to normal activities. A friend or family member should drive you home.

If you weren’t sedated, you can go back to usual activities and normal diet right away.

Please ask your doctor if you have any questions about the MRI.

Show Sources


International Society for Magnetic Resonance in Medicine: "Magnetic Resonance Imaging: Information for Patients." "Cardiac MRI."

National Heart Lung and Blood Institute: "Explore Cardiac MRI."

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