What is an exercise ECG or stress test?
Some heart problems only show up when the heart is working hard (or stressed). An exercise ECG is a noninvasive diagnostic test that measures the heart's electrical activity at rest and while you exercise. It is sometimes called a stress test or a treadmill test because you usually walk or run on a treadmill. This test can detect whether the heart is getting enough blood and oxygen. It also helps to determine the level of exercise that is safe for you.
Who might have an exercise ECG?
The exercise ECG is usually the first noninvasive stress test given to women with risk factors or symptoms of heart disease. Because it is easy to perform, widely available, and excellent for ruling out heart problems, this test is usually used before noninvasive imaging tests such as echocardiography and nuclear stress tests. Women older than 55 and men older than 45 who don't work out regularly but plan to start a vigorous exercise program should have an exercise ECG to determine a safe level of exercise.2
Who should not have an exercise ECG?
If you are unable to perform physical activity due to older age, arthritis, or excess weight, you should not have an exercise ECG. In this situation, you will be sent for a noninvasive imaging test—probably echocardiography or a nuclear stress test—using a chemical that mimics the effects of exercise on the heart If you had an abnormal or inconclusive resting ECG, you will be sent for an imaging exercise test rather than an exercise ECG test. The heart medication digoxin (digitalis) can affect the accuracy of exercise ECG testing, even if you stop taking it up to 2 weeks before the test. If you are taking digoxin, you will be referred for a noninvasive imaging test instead of an exercise ECG.
How do I prepare for an exercise ECG?
You cannot smoke, eat, or drink anything other than water for three to four hours before an exercise ECG. If you have diabetes, you should discuss dietary concerns for the day of the test with your healthcare provider in order to control your blood sugar levels. Talk to your doctor about any medications or dietary supplements you are taking because these may affect the accuracy of the test. You may have to stop taking or reduce the dosage of certain medications before the test.
You should wear comfortable, loose clothing and shoes appropriate for exercising.
What does an exercise ECG entail?
You will remove your clothes from the waist up (you can keep your bra on) and wear a gown. You will lie down and a nurse or technician will thoroughly clean (and shave if necessary) 10 to 12 areas on your chest, arms, and legs. Small sticky patches will be attached to these areas of your skin. The patches are connected by wires to the electrocardiograph machine.
To determine your target heart rate, the nurse will note your age, height, weight, and what medications you currently take. You will then need to lie perfectly still for about a minute while your resting heart rate and blood pressure are measured. You will wear a blood pressure cuff for the exercise portion. You will start to exercise slowly on a treadmill or a stationary bicycle. After 3 minutes, your blood pressure is taken again. The speed and elevation of the treadmill or bicycle is increased about every 3 minutes. During the test, the doctor will speak with you and monitor your physical condition, heart rate, and ECG. You may have to wear a small mask over your mouth so that the oxygen and carbon dioxide levels in the air you breathe out can be measured. The exercise portion will end when you reach your target heart rate or if you ask to stop because of fatigue or symptoms. The resting portion lasts 1 to 2 minutes. The exercise portion lasts 12 to 15 minutes.
What happens after an exercise ECG?
You can eat, drink, and resume normal activities immediately following the test. If you don't exercise regularly, you may experience chest pain, tiredness, muscle aches, and shortness of breath afterwards. A preliminary report may be available right after the test, but the completed report usually takes a day or two.
What does a negative (normal) exercise ECG indicate?
If the test is negative (normal), you are considered to be at low risk for future heart problems such as a heart attack. A negative test also rules out the need for further invasive testing such as cardiac catheterization.
What does a positive (abnormal) exercise ECG indicate?
If you have a positive (abnormal) test, you will be sent for further testing because a positive exercise ECG alone is not enough to diagnose heart disease. If you have a positive test or one that is not clearly positive or negative, you will be referred for another type of noninvasive test such as echocardiography or a nuclear stress test.
How accurate is the exercise ECG in women?
The exercise ECG is very accurate for ruling out heart problems but it is less accurate than other noninvasive diagnostic tests for detecting heart problems. It is also less accurate in women than in men. 3, 4 Women are prone to false positive tests – the tests shows a problem but in reality there isn't one.5 Women are also more likely to have an inconclusive test–one that is not clearly positive or negative. Female hormones can affect the test. If you still get periods, you should let the tester know what stage of your menstrual cycle you are at; if you are postmenopausal, tell them whether or not you are taking hormones. A negative (normal) test is just as reliable in women and men.
What if I feel chest pain during an exercise ECG?
During an exercise ECG, you will be asked to continue exercising until you reach your target heart rate. If you experience fatigue or symptoms before this, you can ask to stop. In men, chest pain during exercise is usually a classic sign of heart disease – a cardiac catheterization will show blockages in the arteries of the heart. However, women often experience chest pain during an exercise ECG when there are no blockages in the arteries of the heart.6 The reasons for the chest pain are not fully understood, but female hormones may play a role.
Next: What your response to exercise says about your heart risk
