What is a pharmacological Cardiac MRI stress test?
A pharmacological Cardiac MRI stress test is a diagnostic test. It is used to check the blood flow to the heart. An exercise stress test is another way to check the blood flow, but if you cannot exercise or if your heart rate does not go up enough with exercise, this test may be done instead. The test can help determine if your heart is getting enough blood while you are active compared to when you are resting.
During the test, you will receive a small amount of medication (adenosine, dipyridamole or regadenoson). This medication makes the coronary arteries open (dilate) much like they do when you exercise. This causes more blood to flow and simulates the effect of exercise for patients who cannot exercise on a treadmill. The medication causes only a slight increase in your heart rate.
A small amount of MRI dye (gadolinium) is injected into a vein while you are resting and again after you receive the medication. An MRI scanner takes pictures of the gadolinium dye as it passes through your heart muscle. This creates computer images of your heart for your doctor to review.
Can I eat or drink the day of the test?
- No, but you may drink small sips of water to help you swallow your medications.
- Avoid all products that contain caffeine for 24 hours before the test. In general, caffeine is found in coffee, tea, colas and other soft drinks, and most chocolate products, as caffeine will interfere with the results of the test. Also avoid decaffeinated or caffeine-free products for 24 hours before the test, as these product contain trace amounts of caffeine.
- DO NOT SMOKE ON THE DAY OF THE TEST. Nicotine will interfere with the test results.
Should I take my medications the day of the test?
Please bring a copy of all of your medications you routinely take, to the test appointment. The list should include all over-the-counter medications and vitamin and herbal supplements you take.
Please follow these guidelines for taking your medications the day of the test:
Medications with caffeine: DO NOT take any over-the-counter medication that contains caffeine (such as Excedrin®, Anacin®, diet pills or NoDoz®) for 24 hours before the test. Ask your physician, pharmacist or nurse if you have questions about other medications that may contain caffeine.
If you have asthma: Your physician will tell you to NOT take theophylline (Theo-Dur) for 48 hours before the test. Please plan to bring your asthma inhaler medication to the test.
If you have diabetes: If you take insulin to control your blood sugar, ask your physician how much insulin you should take the day of the test. Your doctor may tell you to take only half of your usual morning dose and to eat a light meal four hours before the test. If you take pills to control your blood sugar, do not take your medication until after the test is complete. Bring your diabetes medication with you so you can take it when the test is complete. Do not skip a meal when you take your diabetes medication. Doing so can cause your blood sugar levels to drop too low.
If you own a glucose monitor, bring it with you to check your blood sugar levels before and after your test. If you think your blood sugar is low, tell the lab personnel immediately. Plan to eat and take your blood sugar medication after your test.
If you take heart medications: DO NOT take the following heart medications on the day of the test unless your doctor tells you it is okay, or if you need it to treat chest discomfort the day of the test:
- Isosorbide dinitrate (e.g., Dilatrate®, Isordil®)
- Isosorbide mononitrate (e.g., Imdur®, ISMO®, Monoket®)
- Nitroglycerin (e.g., Minitran®, Nitropatches®, Nitrostat®)
- Dipyridamole (Persantine®) – Stop taking 48 hours before the test
- Beta Blockers (e.g., metoprolol, metoprolol XL, atenolol)
Your doctor may also ask you to stop taking other heart medications. If you have any questions about your medications, ask your doctor. Do not stop taking any medication without first talking with your doctor.
What to expect during the test
Your test will take place in the Cardiovascular Imaging Lab. The testing area is supervised by a physician.
An MRI nurse will place two IVs in your arm before starting the MRI scan. Electrodes (small, sticky patches) will be placed on your chest to monitor your EKG. You will also have a blood pressure cuff on your arm to monitor your blood pressure.
Your heart rate, EKG and blood pressure will be monitored throughout the test.
You will need to lie very still inside the MRI scanner for about 45 minutes. You also need to hold your breath for short periods of time while the MRI scanner takes pictures of your heart.
Before you receive the medication through the IV, the nurse will talk to you about the possible side effects of the medication so you will know what to expect.
During the test the MRI scanner will take images of your heart size and function, blood flow through your heart during rest and during cardiac stress, and determine if you have any permanent damage to your heart muscle.
How long will the test last?
The MRI scan will take about 45 minutes. You may spend up to two hours, total, in the Cardiovascular Imaging Lab.
How do I get the results of my test?
After your doctor reviews your test results, they will go into your electronic medical record. Your referring physician will have access to the results and will contact you to discuss them.