Stressing the heart (by exercise or by use of stimulant drugs to make the heart beat faster and more forcibly) can help identify coronary artery disease. In coronary artery disease, blood flow through the coronary arteries (which supply blood to the heart muscle) is partly or completely blocked. If the coronary arteries are only partly blocked, the heart may have an adequate blood supply when the person is resting but not when the heart is working hard. Thus, testing the heart during stress can help identify coronary artery disease.
Because exercise stress testing specifically monitors how the heart is functioning, the testing helps doctors distinguish between problems due to a heart disorder and those due to other problems that limit exercise, such as lung disorders, anemia, and poor general fitness.
During stress testing, exercise or a drug is used to stress the heart, typically making it beat faster, and the person is tested for signs of inadequate blood flow to the heart. The person is also monitored for symptoms that suggest inadequate blood flow to the heart, such as low blood pressure, shortness of breath, and chest pain.
No test is perfect. Sometimes these tests show abnormalities in people who do not have coronary artery disease (a false-positive result). Sometimes tests do not show any abnormalities in people who have the disease (a false-negative result). In people without symptoms, especially younger people, the likelihood of coronary artery disease is low, despite an abnormal test result. In such cases, a positive result is usually more likely to be false than true. These false-positive results may cause considerable worry and medical expense. For these reasons, most experts discourage routine exercise stress testing (such as for screening purposes before an exercise program is begun or during an evaluation for life insurance) in people who do not have symptoms.