Two Johns Hopkins studies have strongly affirmed the value of treadmill exercise tests in diagnosing heart disease in middle-aged women and men before symptoms occur.
“The current guidelines say that it’s not necessary to do routine treadmill exercise tests on people without symptoms, but our studies suggest that for those with high cholesterol or other diseases, it might be warranted,” says Samia Mora, lead author of both studies and a cardiology fellow at Hopkins. “Women with abnormal or inconclusive exercise tests could benefit from aggressive risk-factor modification, as can men who have no known heart disease but who are found during exercise testing to have signs of artery blockages, arrhythmias or low exercise capacity.”
Results of the studies, presented March 17 and 19 at the annual meeting of the American College of Cardiology in Atlanta, showed that women who had abnormal or inconclusive test results were up to 2.6 times more likely to die of cardiovascular disease than counterparts who had normal results. Similarly, men whose tests showed some form of heart complications were twice as likely to die from heart disease as those with normal tests. Many participants had high cholesterol but no standard symptoms of heart disease, such as chest pain, heart attack or exercise-related cramping.
The treadmill test, also known as an exercise stress test, tells physicians how well the heart handles physical exertion. The test measures heart rate, blood pressure and the electrical function of the heart as the patient walks on a treadmill. The speed at which the patient walks gradually increases, requiring the body to use more oxygen and the heart to pump harder. Treadmill test results can indicate a lack of blood supply through the arteries that go to the heart.
Mora and colleagues studied data from the national Lipid Research Clinics Prevalence Study at Hopkins and nine other medical centers from 1972 to 1976. They studied death rates and causes among 3,775 men ages 30 to 79 and 2,001 women ages 40 to 80 who underwent a treadmill exercise test at the start of the study and then were followed for an average of 20 years by annual mailed questionnaires and/or telephone or home visits. Deaths were ascertained by death certificates, hospital records or speaking with the participants’ family members.
Among women, 30 percent of those with abnormal test results died during the follow-up period versus 22 percent who had inconclusive tests and 13 percent who had normal tests. In addition, women with abnormal and inconclusive tests were 2.4 and 2.6 times more likely to die from cardiovascular disease as those with normal tests, and 1.4 and 1.7 times more likely to die from any cause, adjusting for age and other known cardiac risk factors.
In the men’s study, 10 percent of participants tested positive for cardiovascular disease. During the follow-up period, 45 percent with positive tests died versus 32 percent with inconclusive tests and 13 percent with normal tests. Men with positive results were twice as likely to die from heart disease and 1.6 times more likely to die from any cause.
Other study authors were Yadong Cui, Maura K. Whiteman, Jodi A. Flaws and Roger S. Blumenthal.