A stress test, also called an exercise stress test, is used to gather information about how well your heart works during physical activity. Because exercise makes your heart pump harder and faster than it does during most daily activities, an exercise stress test can reveal problems within your heart that might not be noticeable otherwise.
An exercise stress test usually involves walking on a treadmill or riding a stationary bike while your heart rhythm, blood pressure and breathing are monitored.
Your doctor may recommend an exercise stress test if he or she suspects you have coronary artery disease or an irregular heart rhythm (arrhythmia). An exercise stress test may also be used to guide your treatment if you've already been diagnosed with a heart condition.
Why it's done
Your doctor may recommend an exercise stress test to:
- Diagnose coronary artery disease. Your coronary arteries are the major blood vessels that supply your heart with blood, oxygen and nutrients. Coronary artery disease is a condition that develops when these arteries become damaged or diseased — usually due to a buildup of deposits containing cholesterol called plaques. If you have symptoms such as shortness of breath or chest pains with exertion, an exercise stress test can help determine if they're related to coronary artery disease.
- Diagnose heart rhythm problems (arrhythmias). Heart arrhythmias occur when the electrical impulses that coordinate your heart rhythm don't function properly, causing your heart to beat too fast, too slow or irregularly. If you have symptoms such as a racing heartbeat, slow heartbeat or a fluttering in your chest, an exercise stress test can help determine if they're related to an arrhythmia.
Guide treatment of heart disorders. If you've already been diagnosed with coronary artery disease, arrhythmia, valvular heart disease or another heart condition, an exercise stress test can help your doctor find out how well treatment is working to relieve your symptoms. It may also be used to help establish the right treatment plan for you by showing how much exercise your heart can handle.
In some cases, stress tests may be used to help determine the timing of cardiac surgery, such as valve replacement. In some people with heart failure, results from a stress test may help the doctor evaluate the need for heart transplantation or other advanced therapies.
Your doctor may recommend a procedure called a nuclear stress test if a routine exercise stress test doesn't pinpoint the cause of your symptoms. A nuclear stress test is a similar procedure that includes the use of radioactive dye and a special scanner to create images of your heart muscle.
An exercise stress test is generally safe, and complications are rare. But, as with any medical procedure, it does carry a risk of complications.
Potential complications include:
- Low blood pressure. Blood pressure may drop during or immediately after exercise and cause dizziness. It usually goes away when you stop exercising.
- Abnormal heart rhythms (arrhythmias). Arrhythmias brought on by an exercise stress test usually go away shortly after you stop exercising.
- Heart attack (myocardial infarction). Although very rare, it's possible that an exercise stress test could provoke a heart attack.
How you prepare
You may be asked not to eat, drink or smoke for two hours or more before an exercise stress test. You can take your medications as usual, unless your doctor tells you otherwise.
If you use an inhaler for asthma or other breathing problems, bring it with you to the test. Make sure your doctor and the health care team member monitoring your stress test know that you use an inhaler.
Wear or bring comfortable clothes with you to the exercise stress test.
What you can expect
When you arrive for your exercise stress test, your doctor asks you about your medical history and how often you typically exercise. This helps determine the amount of exercise that's appropriate for you during the stress test.
During an exercise stress test
Before you start the test, a member of your health care team places sticky patches (electrodes) on your chest, legs and arms. The electrodes are connected by wires to an electrocardiogram (ECG or EKG) machine. The electrocardiogram records the electrical signals that trigger your heartbeats. A blood pressure cuff is placed on your arm to check your blood pressure during the exercise stress test.
You then begin slowly walking on the treadmill or pedaling the stationary bike. As the test progresses, the speed and incline of the treadmill increases. A railing is provided on the treadmill that you can use for balance, but don't hang on to it, as that may skew the results of the test. On a stationary bike, the resistance increases as the test progresses, making it harder to pedal. During the test, you may be asked to breathe into a tube to measure the gases in your breath as you exhale.
The length of the test depends on your physical fitness and symptoms. The goal is to have your heart work hard for about eight to 12 minutes in order to thoroughly monitor its function. You continue exercising until your heart rate has reached a set target or until you develop symptoms that don't allow you to continue. These signs and symptoms may include:
- Moderate to severe chest pain
- Severe shortness of breath
- Abnormally high or low blood pressure
- An abnormal heart rhythm
- Certain changes in your electrocardiogram
A typical exercise stress test lasts 15 minutes or less. You may stop the test at any time if you're too uncomfortable to continue exercising.
Depending on your medical history, your stress test may also include:
- Medication to stimulate your heart. If you can't exercise long enough to increase your heart rate, or if you're unable to exercise at all due to a medical condition such as arthritis, your doctor may give you medication to increase your heart rate or increase blood flow to your coronary arteries as a substitute for exercising.
- Echocardiogram. An echocardiogram uses sound waves to produce images of your heart, allowing your doctor to see how your heart is beating and pumping blood. In some cases, you may have an echocardiogram before you exercise and after you're done. Your doctor can use the images from the echocardiograms to help identify abnormalities in the heart muscle and valves.
- Nuclear stress test. Another stress test known as a nuclear stress test helps measure blood flow to your heart muscle at rest and during exercise. It's similar to a routine exercise stress test but with images in addition to an electrocardiogram. Trace amounts of radioactive material — such as thallium or a compound known as sestamibi (Cardiolite) — are injected into your bloodstream. Special cameras are used to detect areas in your heart that receive less blood flow.
- Computerized tomography (CT) and magnetic resonance imaging (MRI). In some cases, your doctor may use these imaging technologies to visualize your heart under stress.
After an exercise stress test
After you stop exercising, you may be asked to stand still for several seconds and then lie down for about five minutes with the monitors in place so that they can continue taking measurements as your heart rate and breathing return to normal.
When your exercise stress test is complete, you may return to your normal activities for the remainder of the day.
If the information gathered during your exercise stress test shows your heart function to be normal, you may not need any further tests.
However, if the results are normal and your symptoms continue or become worse, your doctor may recommend you have a nuclear stress test or another exercise stress test that includes an echocardiogram before and after exercise. These tests are more accurate and provide more information about your heart function, but they are also more expensive.
If the results of your exercise stress test suggest coronary artery disease or reveal an arrhythmia, the information gathered during the test will be used to help your doctor develop a treatment plan. You may need additional tests and evaluations, such as a coronary angiogram, depending on the findings.
If the purpose of your exercise stress test was to guide treatment for a heart condition, your doctor will use data from the test to establish or modify your treatment plan, as needed.