Stress testing gives your doctor information about how your heart works during physical stress. Some heart problems are easier to diagnose when your heart is working hard and beating fast.
During a stress test, you exercise (walk or run on a treadmill or pedal a bicycle) to make your heart work hard and beat fast. Tests are done on your heart while you exercise.
During a stress test, if you can’t exercise for as long as what’s considered normal for someone your age, it may be a sign that not enough blood is flowing to your heart. However, other factors besides CAD can prevent you from exercising long enough (for example, lung disease, anemia, or poor general fitness).
A stress test also may be used to assess other problems, such as heart valve disease or heart failure.
Doctors usually use stress testing to help diagnose coronary artery disease (CAD). They also use stress testing to see how severe CAD is in people who have it.
CAD is a condition in which a fatty material called plaque (plak) builds up in the coronary arteries. These arteries supply oxygen-rich blood to your heart.
Plaque narrows the arteries and reduces blood flow to your heart muscle. It also makes it more likely that blood clots will form in your arteries. Blood clots can partly or completely block blood flow. This can lead to chest pain or a heart attack.
You may not have any signs or symptoms of CAD when your heart is at rest. But when your heart has to work harder during exercise, it needs more blood and oxygen. Narrowed arteries can’t supply enough blood for your heart to work well. As a result, signs and symptoms of CAD may only occur during exercise.
A stress test can detect the following problems, which may suggest that your heart isn’t getting enough blood during exercise.
Abnormal changes in your heart rate or blood pressure.
Symptoms such as shortness of breath or chest pain, which are particularly important if they occur at low levels of exercise.
Abnormal changes in your heart’s rhythm or electrical activity.
There are two main types of stress testing: Standard Exercise Stress Test and Imaging Stress Test.
Standard Exercise Stress Test
A standard exercise stress test uses an EKG/ECG (electrocardiogram) to detect and record the heart’s electrical activity. An EKG/ECG shows how fast your heart is beating and the heart’s rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through each part of your heart.
During a standard stress test, your blood pressure will be checked. You also may be asked to breathe into a special tube during the test. This allows your doctor to see how well you’re breathing and measure the gases that you breathe out. A standard stress test shows changes in your heart’s electrical activity. It also may show signs that your heart isn’t getting enough blood during exercise.
Imaging Stress Test
Some stress tests take pictures of the heart when you exercise and when you’re at rest. These imaging stress tests can show how well blood is flowing in various parts of your heart and/or how well your heart squeezes out blood when it beats. One type of imaging stress test involves echocardiography (echo). This test uses sound waves to create a moving picture of your heart. An exercise stress echo can show how well your heart’s chambers and valves are working when your heart is under stress. The test can identify areas of poor blood flow to your heart, dead heart muscle tissue, and areas of the heart muscle wall that aren’t contracting normally. These areas may have been damaged during a heart attack, or they may not be getting enough blood.
Other imaging stress tests use radioactive dye to create pictures of the blood flow to your heart. The dye is injected into your bloodstream before the pictures of your heart are taken. The pictures show how much of the dye has reached various parts of your heart during exercise and while you’re at rest. Tests that use radioactive dye include a thallium or sestamibi stress test and a positron emission tomography (PET) stress test. The amount of radiation in the dye is thought to be safe and not a danger to you or those around you. However, if you’re pregnant, you shouldn’t have this test because of risks it might pose to your unborn child.
Imaging stress tests tend to be more accurate at detecting CHD than standard (nonimaging) stress tests. Imaging stress tests also can predict the risk of a future heart attack or premature death.
An imaging stress test may be done first (as opposed to a standard exercise stress test) if you:
Other Names for Stress Testing
Who Requires a Stress Test
You may need stress testing if you’ve had chest pains, shortness of breath, or other symptoms of limited blood flow to your heart.
Imaging stress tests, particularly, can show whether you have coronary heart disease (CAD) or a heart valve problem. (Heart valves are like doors that let blood flow between the heart’s chambers and into the heart’s arteries. So, like CAD, faulty heart valves can limit the amount of blood reaching your heart.)
If you’ve been diagnosed with CAD or recently had a heart attack, a stress test can show whether you can tolerate an exercise program. If you’ve had angioplasty (AN-jee-oh-plas-tee) with or without stents or coronary artery bypass grafting, a stress test can show how well the treatment relieves your CAD symptoms.
You also may need a stress test if, during exercise, you feel faint, get a rapid heartbeat or a fluttering feeling in your chest, or have other symptoms of an arrhythmia (an abnormal heartbeat).
If you don’t have chest pain when you exercise, but still get short of breath, you may need a stress test. The test can help show whether a heart problem, rather than a lung problem or being out of shape, is causing your breathing problems.
For such testing, you breathe into a special tube. This allows a technician to measure the gases you breathe out. Breathing into the special tube and checking the heart as part of a stress test also is done before a heart transplant to help assess whether you’re a candidate for the surgery.
Stress testing isn’t used as a routine screening test for CAD. Usually you have to have symptoms of CAD before a doctor will recommend stress testing.
However, your doctor may want to use a stress test to screen for CAD if you have diabetes. This disease increases your risk for CAD. Currently, though, no evidence shows that having a stress test will improve your outcome if you have diabetes.
What To Expect During Stress Testing
During all types of stress testing, a technician or nurse will always be with you to closely check your health status.
Before you start the “stress” part of a stress test, the technician or nurse will put sticky patches called electrodes on the skin of your chest, arms, and abdomen. To help an electrode stick to the skin, the technician or nurse may have to shave a patch of hair where the electrode will be attached. The electrodes are connected to an EKG/ECG (electrocardiogram) machine. This machine records your heart’s electrical activity and shows how fast your heart is beating and the heart’s rhythm (steady or irregular). An EKG/ECG also records the strength and timing of electrical signals as they pass through each part of your heart.
The technician or nurse will put a blood pressure cuff on your arm to check your blood pressure during the stress test. (The cuff will feel tight on your arm when it expands every few minutes.) Also, you may be asked to breathe into a special tube so the gases you breathe out can be measured.
After these preparations, you’ll exercise on a treadmill or stationary bicycle. During the test, the exercise level will get harder. You can stop whenever you feel the exercise is too much for you.
What To Expect After Stress Testing
After stress testing, you’ll be able to return to your normal activities. If you had a test that involved radioactive dye, your doctor may ask you to drink plenty of fluids to flush it out of your body. You also shouldn’t have certain other imaging tests until the dye is no longer in your body. Your doctor can advise you about this.
What Does Stress Testing Show?
Stress testing gives your doctor information about how your heart works during physical stress (exercise) and how healthy your heart is.
A standard exercise stress test uses an EKG/ECG (electrocardiogram) to monitor changes in your heart’s electrical activity. Imaging stress tests take pictures of blood flow in various parts of your heart. They also show your heart valves and the movement of your heart muscle.
Both types of stress tests are used to look for signs that your heart isn’t getting enough blood flow during exercise. Abnormal test results may be due to coronary heart disease (CAD) or other factors, such as a lack of physical fitness.
If you have a standard exercise stress test and the results are normal, no further testing or treatment may be needed. But if your test results are abnormal, or if you’re physically unable to exercise, your doctor may want you to have an imaging stress test or other tests. Even if your standard exercise stress test results are normal, your doctor may want you to have an imaging stress test if you continue having symptoms (such as shortness of breath or chest pain).
Imaging stress tests are more accurate than standard exercise stress tests, but they’re much more expensive. Imaging stress tests show how well blood is flowing in the heart muscle and reveal parts of the heart that aren’t contracting strongly. They also can show the parts of the heart that aren’t getting enough blood, as well as dead tissue in the heart, where no blood flows. (A heart attack can cause some tissue in the heart to die.)
If your imaging stress test suggests significant CAD, your doctor may want you to have more testing and/or treatment.
What Are the Risks of Stress Testing?
There’s little risk of serious harm from any type of stress testing. The chance of these tests causing a heart attack or death is about 1 in 5,000. More common, but less serious side effects linked to stress testing include:
Arrhythmia (an abnormal heartbeat). Often, an arrhythmia will go away quickly once you’re at rest. But if it persists, you may need monitoring or treatment in a hospital.
Low blood pressure, which can cause you to feel dizzy or faint. This problem may go away once your heart stops working hard; it usually doesn’t require treatment.
Jitteriness or discomfort while getting medicine to make your heart work harder (you may be given medicine if you can’t exercise). These side effects usually go away shortly after you stop getting the medicine. In some cases, the symptoms may last a few hours.
Also, some of the medicines used for pharmacological stress tests can cause wheezing, shortness of breath, and other asthma-like symptoms. In some cases, these symptoms may be severe and require treatment.