Dear Doctor: I'm a 56-year-old man. I have been out of breath lately and have had some mild chest pains. My doctor wants me to have a stress test. Is it really necessary? What will it entail?


Dear Reader: The purpose of a stress test is to see how someone's heart behaves when it's being asked to work hard. These types of tests have a number of uses. For instance, they can help assess general cardiac health; identify and evaluate various types of heart disease or arrhythmias; and help to gauge the success of medications or treatments for cardiac-related ailments.


For people living with heart disease or recovering from a cardiac event, a stress test can help pinpoint the type and intensity of exercise that is safe. A stress test can also be used to confirm whether certain symptoms, which can have a variety of causes, are heart-related. This includes the shortness of breath and chest discomfort that you have described.


The most common stress tests involve walking on a treadmill or riding a stationary bicycle. While the person exercises, a variety of devices measure and monitor blood pressure, heart rate, oxygen saturation and the electrical activity of the heart. Some stress tests, which evaluate lung function, will measure oxygen use. The activity level of a stress test begins low and slow, then gradually increases. The idea is that, as the heart is asked to work harder and harder, underlying problems may be revealed. This can include the onset of physical symptoms such as dizziness, unusual breathlessness or chest pain, or abnormal changes to the electrical activity of the heart.


When you schedule a stress test, you'll be asked to stop eating or drinking for a set period of time before the test begins, generally a few hours. You will also be instructed not to smoke and to abstain from alcohol and caffeine. Your doctor will ask you what medications and supplements you take on a regular basis, and will let you know if any of them need to be paused. If you have asthma and use an inhaler, be sure to let your doctor know, and bring the inhaler with you.


Electrodes to capture the electrical activity of your heart are taped to various parts of your chest, and a blood pressure cuff is attached to your arm. A pulse oximeter, to measure blood-oxygen saturation, may be clipped to a finger. During the active portion of the test, usually 10 to 15 minutes, you will exercise at an increasingly higher rate, until you reach a target goal. If symptoms develop at any point, the test is cut short. These can include chest pain, dizziness, shortness of breath and abnormal changes to blood pressure or electrical activity. It's important to let the tech administering the test know if you feel discomfort at any time. Monitoring may continue after the test is complete to see how the heart and body recover.


Within the next few days, your doctor will review the test results with you. If coronary disease is suspected, either treatment or additional testing may be recommended.


Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.