An exercise stress test shows how your heart behaves when it has to work harder. Many heart problems, especially narrowed coronary arteries, cause no changes at rest and only show up during exertion, when the heart muscle needs more blood than a narrowed artery can deliver. By recording your ECG, heart rate and blood pressure while you walk on a treadmill at gradually increasing speed and incline, a stress test brings those problems into view under controlled, supervised conditions.
The test is noninvasive. The exercise portion usually lasts about 10 to 15 minutes, and the whole appointment, including preparation and recovery, takes roughly an hour. You are monitored throughout, the pace is increased in stages, and the test stops if symptoms or the readings call for it.
At NYMD Center we order stress testing as part of the evaluation of symptoms that come on with effort, to check how well treatment is working, and to give an objective measure of fitness. The test is not done in our office; we arrange it by referral, and your physician reviews the results with you. This page explains who needs a stress test, how it works, how to prepare and what the results mean.
What a stress test looks for and who needs one
A treadmill ECG stress test answers several practical questions. Does exercise bring on changes on the ECG that suggest reduced blood flow to the heart muscle (ischemia)? Do your symptoms, such as chest pain, pressure or shortness of breath on exertion, reproduce during the test, and if so, at what level of effort? How much exercise can you do, and how does that compare with others of your age and sex? Does your heart rhythm change with exertion, with extra beats or an irregular rhythm appearing or disappearing? And how do your heart rate and blood pressure respond?
We commonly order a stress test for chest discomfort or breathlessness that comes on with activity, for palpitations or lightheadedness during exercise, to see whether treatment for known heart disease is working, and sometimes before starting a vigorous exercise program in someone with symptoms or significant risk factors.
A stress test is not a screening test for people who feel well. The U.S. Preventive Services Task Force recommends against screening with resting or exercise ECG in adults without symptoms who are at low risk of cardiovascular disease, and finds the evidence insufficient for those at intermediate or high risk. For people without symptoms, we usually focus on heart and stroke risk factor screening instead: blood pressure, cholesterol, blood sugar, smoking and family history.
How we evaluate you at NYMD Center
Before a stress test we take a history, examine you and review a resting ECG. The resting tracing matters: certain baseline ECG patterns make an exercise ECG hard to interpret, and in that case imaging is added. We also confirm that a stress test is safe for you. People with unstable symptoms, such as chest pain at rest or chest pain that is rapidly worsening, need urgent evaluation rather than an elective treadmill test. When a stress test is appropriate, we send the referral and your records to the testing facility and tell you how to prepare.
How the test works
Electrodes are placed on your chest and connected to an ECG monitor, and a blood pressure cuff goes on your arm. After baseline readings, you begin walking on the treadmill slowly. Every few minutes the speed and incline increase. Throughout the test the testing staff watch your ECG, heart rate, blood pressure and symptoms, and ask how you feel. The goal is usually to reach a target heart rate based on your age, or to exercise until you are too tired to continue.
The test stops early if you develop chest pain, significant shortness of breath, dizziness, a blood pressure that rises or falls too much, or a worrying rhythm, and you can ask to stop at any time. After the exercise you rest while recording continues until your heart rate and blood pressure return toward baseline.
Variants arranged when needed
Some people need more than an ECG during exercise. A stress echocardiogram adds ultrasound images of the heart before and immediately after exercise, showing whether any part of the heart muscle stops moving normally under stress; see our echocardiogram page. A nuclear stress test uses a small amount of radioactive tracer and imaging to map blood flow to the heart muscle. For people who cannot walk on a treadmill because of arthritis, lung disease or other limitations, a pharmacologic stress test uses medication to make the heart respond as it would to exercise, combined with echo or nuclear imaging. We arrange these tests when your situation calls for them.
Safety
An exercise stress test is generally safe. Mayo Clinic lists the possible complications as low blood pressure, irregular heart rhythms and, rarely, a heart attack. Those risks are the reason the test is supervised, stopped at the first sign of trouble, and carried out only after we have confirmed it is appropriate for you.
How to prepare
Wear comfortable clothes and walking or running shoes. Follow the instructions you receive about eating: usually you avoid a heavy meal for several hours before the test, though a light meal may be allowed. Avoid caffeine, including coffee, tea, energy drinks and some over-the-counter medicines, for the period you are instructed, typically the day before and the day of the test. Do not smoke beforehand.
Medications need special attention. Some heart medications, particularly beta blockers, blunt the heart rate response to exercise, and your physician may ask you to hold them before the test. Only stop a medication if your physician specifically tells you to. If you have diabetes, ask how to adjust your meals and diabetes medications, and bring your glucose meter. If you use an inhaler for asthma, bring it.
What results mean
A normal stress test means you reached an adequate level of exercise without ECG changes suggesting ischemia, without symptoms, and with a normal heart rate and blood pressure response. That is reassuring, though no test is perfect. An abnormal test may show ECG changes, symptoms, an abnormal blood pressure response or rhythm changes during exercise. Depending on the result, the next step may be medication and risk factor control, a stress test with imaging to clarify the finding, or referral to cardiology for further evaluation. Exercise capacity itself is useful information and helps guide how active you can safely be.
What to expect at your visit
At your visit with us, we explain why the test is needed and arrange it. At the testing facility, plan on about an hour. You will have time after the test to cool down, and most people can drive home and return to normal activities the same day. When the report comes back, your physician reviews the results with you and explains what they mean for your symptoms and your heart risk.
When to seek care urgently
If you have chest pain at rest, chest pain that is getting more frequent or severe, or chest pain with shortness of breath, sweating, nausea or fainting, do not wait for a scheduled stress test. Call 911.
Questions patients ask
How long does a stress test take?
The exercise itself usually lasts about 10 to 15 minutes, depending on your fitness and how the test goes. Including electrode placement, baseline readings and the recovery period, plan on about an hour. Stress tests that add echocardiogram or nuclear imaging take longer, and we give you specific timing if one of those is arranged.
Should I stop my medications before a stress test?
Only if your physician tells you to. Some heart medications, especially beta blockers, keep the heart rate from rising with exercise, so your physician may ask you to hold them before the test. Other medications should be continued. If you have diabetes, ask how to adjust your meals and medications. Bring a list of everything you take.
Is a stress test safe?
An exercise stress test is generally safe. Possible complications include low blood pressure, irregular heart rhythms and, rarely, a heart attack. That is why the test is supervised from start to finish, stopped early for symptoms or concerning readings, and done only after we confirm it is appropriate for you. You can also ask to stop at any time.
What if I cannot walk on a treadmill?
If arthritis, lung disease or another condition keeps you from exercising enough, a pharmacologic stress test can be arranged. Medication is used to make the heart work harder, as it would during exercise, and imaging with echocardiography or a nuclear scan shows how the heart responds. Your physician will recommend the right option for you.
Should I get a stress test even if I feel fine?
Usually not. The U.S. Preventive Services Task Force recommends against screening low-risk adults without symptoms with a resting or exercise ECG. For people who feel well, checking blood pressure, cholesterol, blood sugar, smoking and family history is more useful. We order a stress test when there are symptoms or a specific clinical question to answer.