Stress Testing, What is It Good For?
Several years ago I recall someone claiming that the use of a treadmill for stress testing was outdated and inaccurate. Nothing could be further from the truth. Indeed, putting someone on a treadmill and observing what they are able to do safely is one of the most objective tests that a cardiologist can use.
Imagine this, you have two friends - one of whom looks fit but always claims to be tired and unable to do things, the other appears out of shape, but claims to get through the day with a bounce in the step. How do you determine which one is at greater risk of having a problem? Answer: measure whatever you can.
That is what doctors do and it is especially useful when there is a disagreement about what a person reports. This actually happens quite a bit, especially when the spouse is in the room. "I can walk and run all day" followed by "You can’t even bring up the groceries without gasping for breath" from the spouse. "I never have any pain" becomes "then what happened last Tuesday night?" when the spouse is there.
Stress testing is often done with a treadmill, though in some places a bicycle is preferred (more Europeans bicycle for sport than Americans, and some people may be more comfortable on a bike than a treadmill). Doctors use different protocols (3 minute stages with increasing incline and speed) to obtain objective information on capacity to perform cardiac work.
Exercise tests have been around for many years and have been validated in all age groups, so that when a person is on the treadmill the comparison is to all others of the same age, not just professional athletes. Everyone’s heart works the same way. Exercise increases our heart rate, blood pressure and cardiac output. When we stop exercising, our heart rate and blood pressure return to normal.
For a properly performed test, after questioning the patient about recent history, application of special electrocardiographic leads ("wiring the patient up" to a monitor) and a brief cardiac examination, the doctor starts the treadmill slowly and the patient walks up a small incline. Blood pressure and heart rate are monitored and the doctor is able to derive information about physical conditioning, anxiety, and the condition of the heart from the monitoring.
Occasionally, the doctor will spot changes in the cardiogram or rhythm that are not felt by the patient. When this occurs, a deficient early warning system may be diagnosed and treatment may be instituted earlier as the patient is unable to determine when they are getting into trouble.
In some patients, the inability to exercise without shortness of breath, chest discomfort, arrhythmias, or electrocardiographic changes signals danger and requires further testing and treatment. In these patients, the finding of an abnormality on the stress test may be life-saving if appropriate treatment is instituted.
In many more cases, however, the doctor is able to determine that patients limit themselves from exercising due to fears about dangers that may be overblown.
As an example, this past month I did an exercise test on a woman who felt that she had always had less exercise endurance then others her own age. Pushing her harder on the treadmill (in the presence of a trained physician so that she could be pushed safely) than she would have pushed herself resulted in a perfectly normal stress test. Given this information, she joined a gym and participated in a program that she had previously felt would be "too much for her." After less than a month she assures me that the stress test "did her a world of good."
If your doctor feels that you should have a stress test, for any reason, do not be afraid of this test that is very safe in experienced hands. But do discuss your medications and whether they should be taken with the doctor beforehand, as some will want you to hold your medicines for 24 hours before the test.
Larry Weinrauch is a cardiologist in Watertown, Massachusetts and is affiliated with Mount Auburn Hospital. He wrote for HealthCentral as a health professional for Heart Health, High Blood Pressure, and High Cholesterol.