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What To Expect Before Cardiac CT

Your doctor will tell you how to prepare for the cardiac CT scan. He or she may tell you to avoid caffeine and not eat anything for 4 hours before the scan. You’re usually allowed to drink water before the test.

If you take medicine for diabetes, talk with your doctor about whether you'll need to change how you take it on the day of your cardiac CT scan.

Tell your doctor whether you:

  • Are pregnant or might be pregnant. Even though cardiac CT uses a low radiation dose, the x rays may harm your fetus.
  • Have asthma or kidney problems or are allergic to any medicines, iodine, or shellfish. These problems can increase your chance of having an allergic reaction to the contrast dye that's sometimes used during cardiac CT.

A technician will ask you to remove your clothes above the waist and wear a hospital gown. You also will be asked to remove any jewelry from around your neck or chest.

If you don't have asthma, COPD (chronic obstructive pulmonary disease), or heart failure, your doctor may give you medicine to slow your heart rate. A slower heart rate will help produce better quality pictures. The medicine will be given by mouth or injected into a vein.

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Cardiac CT Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Cardiac CT, visit

February 29, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.