Stress Test

What is an Exercise (Stress) Test?

The exercise test, also called a stress test, shows how the heart works during physical activity. Exercise causes the heart to pump harder and faster. The exercise test can show changes in blood flow within the heart.

In exercise tests, patients usually walk on a treadmill or ride a stationary bike. Health professionals monitor heart rate, blood pressure, and breathing during the test. For people who cannot exercise, medication that affects the heart as if exercising can be given.

The exercise test may be recommended if symptoms of coronary artery disease or irregular heart rhythms known as arrhythmia are observed.

Types of Exercise Tests

Different types of exercise tests are used to assess heart function. All cardiac stress tests include monitoring heart rate, blood pressure, oxygen levels, and electrical activity. However, there are some differences between them.

Standard Treadmill or Bike Test

This is the most common and basic exercise test. It involves walking on a treadmill or riding a stationary bike. A well-trained exercise physiologist usually adjusts the treadmill speed and incline to suit the patient’s walking ability and general fitness. For patients who cannot exercise, drugs are administered to cause the heart to pump harder and faster and to dilate the coronary arteries.

Cardiac Stress Echocardiography

Cardiac stress echocardiography is similar to the basic stress test, but provides more detailed data. Specialists take ultrasound images of the heart before and during peak exercise. This cardiac imaging test is used to assess blood flow in the heart, the chambers, and heart valves.

Cardiac stress echocardiography is needed if the initial exercise test results are inconclusive. It helps understand how well the heart chambers are perfused during exercise.

Nuclear Stress Test (Thallium or MIBI Scan)

The nuclear stress test, an advanced form of exercise testing, uses safe levels of a radioactive substance along with cardiac imaging to assess heart function. Specialists take images of the heart before and after exercise. A cardiologist compares blood flow to the heart muscle during rest and stress. A decrease in signal typically indicates blockage in one or more arteries in the heart.

Nuclear cardiac stress tests can:

• Determine the severity of coronary artery blockages
• Evaluate whether previous treatments like stents or bypass surgery are working properly
• Avoid more invasive heart tests like cardiac catheterization
• Assess whether the heart is healthy enough for non-cardiac surgery or exercise

Cardiac Rehabilitation Stress Test

If specialists recommend cardiac rehabilitation, the program may include a stress test. Rehabilitation is a medically supervised exercise program that helps people with heart conditions become more physically active.

Cardiac rehabilitation stress testing includes:

• An entry stress test to help the rehabilitation team develop an exercise program suited to the patient’s abilities
• An exit test to evaluate the patient’s progress and establish a long-term exercise plan after completing rehabilitation

Why is an Exercise Test Performed?

Situations where exercise testing is frequently preferred include:

• How well the heart pumps blood
• Whether the heart is getting enough blood
• The patient’s physical condition compared to others of the same age and sex
• To explain symptoms such as chest discomfort, shortness of breath, rapid heartbeat, and dizziness

Additionally, it helps identify heart problems such as:

• Issues in the heart muscles and valves
• Inadequate blood supply to the heart muscle
• Electrical stability of the heart between rest and exercise

The exercise test helps doctors determine whether further, often more invasive, tests are needed to confirm a diagnosis. It also helps assess whether treatment reduces heart attack risk and improves how patients feel.

How is the Exercise Test Performed?

The exercise test begins by making the heart pump harder and faster. For this, patients need to walk on a treadmill or ride a stationary bike. Before patients start exercising, electrodes and blood pressure monitoring devices are placed on them to measure values.

While patients are exercising, the following values are measured and evaluated:

• Blood pressure
• Heart rate
• Oxygen level
• Electrical activity in the heart
• How the heart performs compared to other people based on age and gender

The stages of the exercise test are as follows:

• First, the technician takes vital signs, including the patient’s resting heart rate and blood pressure.
• Small sticky electrodes are attached to the patient’s chest and arms. These electrodes are connected to the ECG machine.
• Patients begin walking on a treadmill or pedaling a stationary bike. The intensity gradually increases over time.
• Technicians and exercise physiologists periodically ask patients how they feel.
• The test ends after maintaining the target heart rate long enough to record heart function readings. This usually lasts 10–15 minutes. The target heart rate is higher than the resting rate and varies depending on the patient’s age and overall health.
• If patients experience severe symptoms or wish to stop, technicians may terminate the test early.

Some patients may not be suitable for exercise due to their general health or physical limitations. These patients are given medication intravenously. The drugs mimic exercise by making the heart beat harder and faster. It takes about an hour for the effects of the medication to be felt.

Stress echocardiogram tests are similar to exercise tests. However, in this test, patients lie on a table before and after exercising, and ultrasound images of their hearts are taken. This test lasts about 1 hour, with 15 minutes dedicated to exercise.

In a nuclear stress test, a radioactive substance is injected. A small amount of this substance is enough to show fine details of heart activity during a complex imaging study. The radiation level is low and not associated with any known immediate side effects.

After the initial scan, patients exercise or are given medication that makes the heart work harder. The PET test usually takes about 30 minutes. The total duration of the test is around 3–4 hours, though patients typically spend about 15 minutes exercising.

Which Diseases Are Diagnosed with an Exercise Test?

The purposes of performing an exercise test include the following:

Diagnosing Coronary Artery Disease

Coronary arteries are the main blood vessels that supply blood and oxygen to the heart. Coronary artery disease occurs when these arteries are damaged or diseased. Cholesterol buildup and inflammation in the heart arteries typically cause coronary artery disease.

Diagnosing Irregular Heartbeats

Irregular heartbeat, known as arrhythmia, can cause the heart to beat too fast or too slow.

Determining Whether Heart Treatment is Working

In diagnosed and treated heart conditions, exercise tests are used to evaluate the course of the disease. They also help determine whether the treatment is effective and whether new treatment methods are needed.

In addition, heart patients should undergo an exercise test in the following cases:

• Before starting an exercise routine
• Individuals with a high risk of complications due to personal or family medical history
• People who also have diabetes

Before Surgery

Exercise testing is also done before surgeries such as valve replacement or heart transplant. This helps determine whether the planned treatment is safe for the patient.

If the exercise test does not clarify the symptoms observed in the patient, specialists may recommend a stress test with imaging. These types of tests include nuclear stress testing or echocardiography with stress.

Diseases

Diseases for which exercise testing is frequently applied include:

• Congenital heart disease
• Congestive heart failure
• Coronary artery disease
• Heart valve disease
• Hypertrophic cardiomyopathy
• Chest pain or discomfort caused by poor blood flow to the heart

In addition, people working in high-risk jobs (such as pilots and professional athletes) may also need stress testing.

How Long Does the Exercise Test Take?

A basic stress test usually takes between 10 and 15 minutes. Additional time is needed to prepare for exercise and for patients to recover afterward.

Stress tests that include echocardiography, nuclear imaging, or MRI usually take longer, and patients may need to stay in the stress lab for up to three hours.

What Are Normal Values for an Exercise Test?

If the results of the exercise test are normal, it means the heart is pumping blood properly and there is adequate blood flow. The medical meaning of this depends on the reason the stress test was performed.

Heart Disease Assessment

Symptoms are not related to a heart problem. Patients may need further evaluation to determine the cause. For example, some anxious individuals may experience chest pain and palpitations even though their hearts are healthy.

Exercise or Surgery Planning

Indicates that the heart is healthy enough to begin an exercise program or undergo surgery.

Heart Disease Monitoring

Indicates that the applied treatments are suitable for the patient and that the heart can keep up with the body's demands.

Abnormal Test Results

Abnormal results may indicate heart disease. For mild heart disease symptoms, healthcare providers may recommend lifestyle changes. To prevent worsening, patients may be prescribed medications to control diabetes, cholesterol, and blood pressure.

If abnormalities occur in the early stages of the test or if large areas of heart tissue are affected, additional tests may be needed. These may include:

• Cardiac catheterization
• CT coronary angiography
• Nuclear stress test
• Stress echocardiogram

Abnormal results may also mean the heart is not strong enough for exercise or surgery. Additional treatments may be needed to help avoid a heart attack or heart failure.

What Should Be Considered Before an Exercise Test?

To prepare for an exercise test, the following should be done:

• Do not eat or drink anything for a few hours before the test. For patients undergoing a nuclear stress test, it is important not to consume anything until after the test.
• Avoid caffeine for 24 hours before the test. This includes tea, coffee, energy drinks, and some medications.
• Do not smoke or use tobacco products.
• Certain prescription medications should not be taken on the day of the test. These may include beta-blockers and asthma medications. Consult a specialist before stopping any medication.
• Patients are advised to try to relax before the test. It’s natural to feel anxious about a heart test, but being nervous may affect the results.
• Wear light, comfortable clothing and walking shoes.

If diabetic patients are on medication, they should not skip meals. Therefore, if medication and meal coordination is needed for test day, they should consult their healthcare provider. If the patient has a glucose meter, they should check blood sugar levels before and after the test.

What Should Be Considered After an Exercise Test?

After the test is completed, specialists continue to monitor the patient’s symptoms, heart rate, blood pressure, and ECG until the values return to normal ranges. This monitoring typically lasts about 15 minutes. Once the patient’s heart rate returns to normal, they can go home.

Who Should Not Take an Exercise Test?

The exercise test is not suitable for everyone. In the following situations, patients may not need the test:

• Those who have been diagnosed with coronary artery disease, received treatment, and have not had new symptoms for years and are doing well with medical care
• Individuals with no risk factors for coronary artery disease or symptoms of coronary artery disease
• People at low risk of heart disease, including non-smokers, physically active individuals, and those following a heart-healthy diet

The test is also not appropriate for people with heart conditions that make exercise testing unsafe. These include:

• Aortic dissection
• Endocarditis, pericarditis, or myocarditis
• Having recently had a heart attack
• Severe aortic valve stenosis
• Uncontrolled abnormal heart rhythm
• Ongoing chest pain