One thing I have learned from my time working on a cardiac unit is that people do not like waiting to get tests done. Partly because they are not allowed to eat prior to certain tests. And like many cardiac tests and procedures, a stress test is no different. So, can you eat before a stress test? The short answer is, unfortunately, no. But on occasion, depending on the facility performing the test, a light breakfast or lunch is allowed.
Feel free to read on to find out what a stress test is, what it measures, why you might need one and what to expect the day of your procedure.
To skip to a quick STRESS TEST PREP CHECKLIST – click here.
What is a Stress Test?
This noninvasive test is used to analyze how your heart reacts under cardiovascular “stress”. This is a great way to prognose your risk of heart disease and provide some answers to why you may be experiencing the symptoms you’re having. But don’t worry, it’s not as worrisome as it sounds. It is very safe and all testing is done in a lab, clinic or hospital. Likewise, a trained medical professional will be monitoring you the entire time. The only stress your body will be under is from one of three activities: 1) walking on treadmill, 2) bicycling on a stationary bike or 3) by medically-induced heart rate raising drugs.
It is also important for you to know that stress tests are usually only useful on patients with intermediate-risk for CAD. Studies show that those who are at low risk may have false-positives. For low risk patients, a cardiac catheterization procedure is recommended instead.
What Is Monitored During a Stress Test?
Now that you are aware that the purpose of a stress test is to analyze and prognose possible heart disease, let’s answer the question of what is being monitored throughout your test.
Throughout the testing period, trained medical staff will be constantly monitoring several things:
- Your heart rate
- Your breathing
- How tired or out of breath you are
- Your blood pressure
- Your electrocardiogram (ECG or EKG)
If you have any concerns during the test, it can be stopped at any time. Let your technician know if you are having any dizziness, fatigue, chest pain, shortness of breath or other symptoms that make you unable to continue. Likewise, the technician will be asking you throughout your test how you are feeling to make sure you are okay to continue.
Why Do I Need a Stress Test?
A stress test shows whether or not your heart’s blood supply is sufficient and if your heart rhythm is normal. A stress test may be recommended by your doctor for several reasons, including to:
- Identify the cause of your heart symptoms – such as chest pain, shortness of breath, dizziness, lightheadedness, etc.
- Diagnose possible heart diseases if you are showing signs and symptoms
- Check the effectiveness of certain procedures you may have had – such as coronary angioplasty and stenting or cardiac bypass surgery
- Create a safe exercise plan – if you are at high risk for developing heart disease
- Identify any heart rhythm changes – usually experienced during exercise
- Determine your risk of heart disease – or other heart-related conditions
Types of Stress Tests
There are different types of stress tests as seen in the graphic below. I’ll provide a brief explanation of each similar but slightly different test.
Treadmill Stress Test
Also known as an exercise stress test or treadmill test.
You will first have electrodes (flat, sticky pads) placed on your chest area. The electrodes are connected to a machine that will monitor your heart throughout your test.
You will then be asked to walk slowly on a treadmill. The speed and/or incline will be adjusted as you go to a faster pace to mimic the effect of going up a small hill. This is done to raise your heart rate to a specific target rate.
At some point, you may be asked to breathe into a mouthpiece or face mask for a couple of minutes. This is to monitor your breathing throughout the exercise.
When you are done on the treadmill, you will have to sit or lie down with the electrodes still in place. Technicians will monitor your heart rate and other vital signs such as blood pressure as they return to normal.
Stress Echo (Treadmill)
This test involves a doctor being present and a sonographer. A sonographer is a medical professional that is trained in using imaging equipment that uses soundwaves to produce a picture of specific body part.
First, the sonographer will place electrodes on your chest. The electrodes will be attached to a monitor that will monitor your heart throughout the test.
Secondly, you will have a resting EKG done to measure your heart rate and blood pressure while at rest. A resting echo, or ultrasound, will also be done at this time. You will have to lie on your left side while the sonographer places a wand (called a transducer) on your chest to capture an image of your heart’s movement and structures.
Then you will finally start the treadmill part of the test. Like the exercise stress test, you will start exercising slowly then work your way up to a more intense pace and incline. Your heart rate, blood pressure, and how you are breathing will be monitored throughout the test and you can stop if you are having any chest pain, severe shortness of breath, or are too exhausted.
Immediately after you get off the treadmill, you will lie back on a exam table to have a second echo done. Again, the sonographer will use the wand to capture images of your heart structures. Then you may walk slowly for a few minutes while your vital signs continue to be monitored by a machine until they return to normal.
For a really easy-to-understand video explaining the treadmill stress echo procedure- click here.
Treadmill Nuclear Stress Test
Also called a nuclear exercise test, this test is similar to a treadmill stress test with the addition of a radioactive tracer being injected into your vein via an IV.
First, a technician will place an IV into a vein in your arm or hand and inject the radioactive tracer. Then you will wait about 20 minutes.
Then the technician will take several images of your heart while at rest. A special camera is used to detect the radiation that the tracer injects to create an image of your heart and the blood flow through it. You will have to lie very still with both arms above your head while the images are taken.
Next, you will have electrodes placed on your chest and a resting EKG will be taken.
Then the treadmill part of the stress test will take place. Like a treadmill stress test, the pace and incline will increase until you reach your target heart rate. A second dose of radioactive tracer will be injected into your IV at this time.
After the treadmill portion is over, you will lie very still again with arms over your head while the second set of images are taken. Each set of images will take about 15-20 minutes.
Adenosine/Persantine Nuclear Stress Test
For patients who are unable to physically complete a treadmill stress test, a pharmacological nuclear stress test is recommended. This type of testing method uses a drug that mimics the effects of exercise on the heart. It is very similar to a treadmill nuclear stress test however does not involve a treadmill.
First, a radioactive tracer is given to you through an IV. Then you will lie perfectly still while medical staff take images of your heart.
Secondly, you will have electrodes attached to your chest. The technician will then administer the vasodilator through your IV. A vasodilator is used to open up your blood vessels to allow a three to five time increase in the blood flowing through your vessels. In this case, either adenosine or persantine are used. Persantine is also know as dipyridamole.
The adenosine or persantine may give you a flushed or warm feeling and will cause your heart to react as if you were exercising. A second radioactive tracer will be given during the exam as your heart functioning and vitals continue to be monitored.
Third, you will wait about 30-40 minutes before having more images taken and your vitals return to normal.
Dobutamine Stress Echo
This is another test that involves a sonographer. A sonographer is a medical professional that is trained in using imaging equipment that uses soundwaves to produce a picture of specific body part.
Dobutamine is an alternative drug to adenosine and persantine. It is used in stress tests where patients are unable to physically walk on a treadmill. It is not approved by the FDA and rarely used currently. However, it can be used in patients who have contraindications to adenosine and persantine- such as in patients who have severe asthma or chronic obstructive pulmonary disease (COPD).
First, a technician will place an IV into a vein in your arm and electrodes on your chest. The electrodes are connected to a machine that will monitor your heart throughout your test.
A resting EKG and echo will be performed. Your vital signs will also be taken at rest and throughout the test. You will have to lie on your left side while the sonographer places a wand (called a transducer) on your chest to capture an image of your heart’s movement and structures. They will take several images throughout your test.
Next, dobutamine will be given though your IV. The dobutamine may give you a flushed or warm feeling and will cause your heart to react as if you were exercising. You may even feel a mild headache.
You can stop the test at any time, especially if you feel any jaw pain, chest pain, dizziness or shortness of breath. The technician will ask you throughout your test how you are feeling as well.
After the test, the IV will be removed from your arm and your heart rate and vitals will be monitored until they return to normal.
What To Expect
It’s always nice to know what to expect prior to having any type of medical testing. Your physician, nurse, or lab tech should fill you in on what to do. For example, certain medications should continue to be taken and others should not. You can always do your own research on what is typical, but consult with your physician or lab that will be performing the test to be sure. Below are some things you can expect the day before testing as well as the day of testing.
The Day Before Your Stress Test
Most facilities prefer you to eat NOTHING after midnight the night before your stress test. However, other medical professionals may say to refrain from eating at least 3 hours before your procedure. Ask your doctor or facility performing the test in order to be sure.
The reasoning behind not eating or drinking anything is just in case you need any other heart procedures done. If your stress test comes back positive, your cardiologist may want to do a cardiac catheterization or other surgical procedure in which you shouldn’t have a full stomach. Having these procedures done back-to-back will not only cut back on coronary intervention time, but also your length of stay at the hospital.
Secondly, you may also want to avoid any caffeine for 12-24 hours prior to your test. This means staying away from coffee, tea, cola or chocolate.
The reasoning behind avoiding caffeine is because caffeine is a stimulant that raises blood pressure levels. Studies show conflicting evidence on whether or not caffeine is directly linked to heart disease however.
If you are a smoker, its also best to avoid smoking starting the day prior to your test. This is mainly because the nicotine in cigarettes may effect your test.
The Day of Your Stress Test
It is best to wear loose, comfortable clothing and flat, walking shoes. Wearing a button up shirt may be best to easier apply the electrodes to your chest. If you have hair on your chest, they may shave it to better place the electrodes to your chest area. And remember to also bring a list of all your medications with you.
Stress tests can take anywhere from 1 hour to 6 hours long, depending on the type of stress test being performed. Therefore, if your stress test is in the early morning, do not expect to be able to eat again until the afternoon or late afternoon.
Do I Need to Change My Diet and Lifestyle?
The answer to this question depends largely on the results of your stress test. Were the results “normal” or “abnormal”? How are you currently living your life? What risk factors do you currently have that put you at risk for heart disease?
Many lifestyle and genetic factors play a role in your health. Diet is only a small part of following a heart healthy lifestyle. Listen to what your doctor tells you and be honest with them about what changes you are willing to make to benefit your health. Start small and continue to make changes where needed.
Some areas in which you can make change right now to support heart health include:
- Eating more fruits, vegetables, nuts and beans
- Getting 150 minutes of exercise each week
- Getting 7-9 hours of sleep each night
- Quit smoking and avoid secondhand smoke
- Manage and reduce stress levels
Overall, a stress test is not something to stress about. You are in good hands with trained medical professionals. And knowing that you can stop the test at any moment should give you some peace of mind as well.
You now know what a stress test is, what it measures along with some reasons your doctor may want you to have one.
Each type of stress test is slightly different but one thing remains the same for them all:
- Your heart rate and vitals will be monitored for them all.
- Each test will give your doctor more information on how to treat and manage your condition.
Stress Test Prep Checklist
Check out this checklist for some reminders and to help prepare yourself.
- American Heart Association. Caffeine and Heart Disease. Accessed: March 15, 2022. Available at: https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/nutrition-basics/caffeine-and-heart-disease
- Centers For Disease Control and Prevention. 2022. Heart Disease and Stroke. Accessed: March 17, 2022. Available at: https://www.cdc.gov/chronicdisease/resources/publications/factsheets/heart-disease-stroke.htm#:~:text=Leading%20risk%20factors%20for%20heart,unhealthy%20diet%2C%20and%20physical%20inactivity.
- Lak HM, Ranka S, Goyal A. Pharmacologic Stress Testing. (Updated Aug 2, 2021). In: StatPearls (Internet). Treasure Island (FL): StatPearls Publishing; Jan 2022 . Accessed: March 17, 2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK555963/
- MedlinePlus. Bethesda (MD): National Library of Medicine (US); (updated December 10, 2020). Stress Tests. Accessed March 15, 2022. Available at: https://medlineplus.gov/lab-tests/stress-tests/
Kiran Campbell is a registered dietitian and entrepreneur with 13 years of experience. She has a degree in psychology as well as dietetics. She is also a proud member of the Academy of Nutrition and Dietetics’ and its Cardiovascular Health and Well-being Dietetics Practice Group among others. Kiran proudly presents and promotes the most up-to-date, science-based nutrition information on all things heart-related. She aims to serve not only individuals with heart disease, but also those wanting to protect against it. Learn more about Kiran by visiting her About Page.