February 29, 1996
Media Contact: John Cramer
Phone: (410) 955-1534
Treadmill and thallium exercise tests, which measure blood flow to the heart during exertion, can predict the onset of heart disease several years in advance in people under age 60 with a close family history of premature heart disease, according to a Johns Hopkins study funded by the National Institutes of Health.
The study suggests that like elevated blood pressure, cholesterol and blood sugar levels, flunking the exercise thallium test is a major risk factor for men and women under 60 with siblings who also developed heart disease before age 60.
"If people with a family history of premature heart disease have an abnormal exercise test and/or thallium scan, they and their physician should consider starting drug therapy to lower their blood pressure and cholesterol," says Roger Blumenthal, M.D., the study's lead author and an assistant professor of medicine. "This aggressive approach is often not taken when patients appear otherwise healthy, even if they are in a high-risk group. But this test may be a good way to target people without symptoms who should be treated more pro-actively and to persuade them to be more vigilant in changing their lifestyle habits to prevent or slow the development of heart disease."
The study's results appear in the March 1 issue of Circulation.
Researchers conducted exercise and thallium imaging tests between 1983 and 1991 on 264 men and women under age 60 who had no symptoms of heart disease but did have brothers or sisters with heart problems before the same age.
Results showed that 19 patients developed heart disease -- a heart attack, severely narrowed arteries or sudden death -- between one and nine years later despite a healthy appearance. Of these 19, six had abnormal results on both tests. Six other people with abnormal results on both tests but without symptoms of heart disease appear to be likely candidates for trouble in coming years, the study suggests. All patients who developed heart disease and all those with abnormal results on both tests were men with an average age of 46, but the findings also likely apply to post-menopausal women with a family history of premature heart disease, Blumenthal says.
In the general population, exercise testing without thallium scanning has been shown to be inaccurate in predicting heart attacks, and studies elsewhere have found that in low-risk groups, particularly those under age 60, exercise thallium tests are not cost-effective.
Thallium scintigraphy is a highly sensitive, two-dimensional imaging test that measures the amount of blood flow through the heart's blood vessels during exercise and shows whether the vessels expand normally to allow more blood to reach the heart.
The study's other investigators were Diane Becker, Sc.D., Taryn Moy, M.S., Josef Coresh, Ph.D., Lora Wilder, Sc.D, and Lewis Becker, M.D. The study was supported by the National Center for Nursing Research and the National Heart, Lung and Blood Institute.