A Guide to Your Stress Test: How to Prepare and What to Expect

If your doctor wants you to undergo a stress test, you may be wondering what to expect. Also called an exercise test or treadmill test, it gauges how your heart responds when working its hardest. It's an important test for cardiologists to get a measure of your heart health. The stress test can help your doctor determine if you have an irregular heartbeat (arrhythmia) or if certain symptoms — such as difficulty breathing — are related to a heart condition.

How to Prepare for the Test

Before you start the test, be sure to tell your doctor what, if any, medications you are currently taking. This includes over-the-counter medications or supplements, such as a multivitamin. Continue taking the medication unless your doctor tells you to stop prior to the test, as is the case with certain heart medications.

Your doctor will ask you to refrain from eating or drinking for two to four hours prior to the test. This is to reduce the likelihood that you'll experience nausea during the test. You'll want to dress comfortably in exercise clothing and sneakers for walking or running.

The Stress Test Process

Once in the exercise laboratory, your doctor will attach electrodes to your arms and chest. The electrodes connect to an electrocardiogram (EKG) machine, which will record your heart's electrical activity. The EKG also monitors your heart rhythm and how fast it's beating. The doctor will also attach a blood pressure cuff to your arm, which will tighten as it expands during the test.

Once you're prepared, you'll exercise on a treadmill or stationary bike. A doctor or nurse will be nearby in case you feel ill during the test. If you're using a treadmill, you'll start by walking in place slowly. The difficulty level will increase gradually, with the treadmill tilting up into an incline and the speed increasing to make you walk faster. Your doctor may ask you to breathe into a tube to measure the amount of oxygen you have used. On a stationary bike, you'll start by pedaling slowly and work up to pedaling faster. The resistance may be adjusted so that pedaling is more difficult, making you and your heart work harder. You may stop the test and rest at any time if the exercise is too difficult or you feel unwell. Otherwise, it will continue until you reach a target heart rate.

If you are unable to exercise, you'll be given medication to simulate exercise by making your heart beat faster and increasing blood flow.

The Follow-Up

Once the test is over, you'll be allowed to rest and drink some water. Your heart activity and blood pressure will continue to be monitored until they return to their normal levels.

Your doctor will give you preliminary results before you leave, but the official result will take a couple of days. According to a report in the American Family Physician, results will typically include any symptoms recorded during the test, why the exercise ended (such as illness or target heart rate reached), blood pressure response, and any observed changes to the EKG. The results may confirm or rule out the existence of a heart murmur, exercise-induced hypotension (decrease in blood pressure), or myocardial ischemia (reduced blood flow). According to a study in Postgraduate Medical Journal, heart failure can manifest as exercise intolerance, and exercise capacity is reduced with even mild heart failure.

Possible Risks of Stress Tests

A heart stress test is fairly safe. It simulates strenuous exercise, such as jogging or running up a flight stairs, so there are only minimal risks associated with a stress test, such as a change in blood pressure or abnormal heart rhythm. Chest pain may also occur, but these complications typically go away shortly after exercising. If you were given medication due to an inability to exercise, you may get a headache or feel jittery or anxious.

Stress tests are just one way for doctors to gauge your heart health, and if you're at risk for severe heart conditions, this will help your health care team determine your treatment plan.