Electron beam computed tomography (EBCT) could help identify older adults with heart disease who otherwise appear healthy when evaluated using standard non-invasive ways, according to a report by University of Pittsburgh researcher Anne Newman, M.D., M.P.H., Division of Geriatric Medicine. Dr. Newman is presenting her results at the 39th annual Conference on Cardiovascular Disease Epidemiology and Prevention, March 25, in Orlando, Fla.
"Healthy older adults, even those with no cardiovascular disease as measured by carotid ultrasound or ankle-arm index (AAI), have a wide range of coronary calcifications as measured by EBCT," said Dr. Newman, who is an associate professor of medicine at the university's School of Medicine and an assistant professor of epidemiology at the university's Graduate School of Public Health (GSPH). "Twenty-five percent of all the people we saw had high coronary calcification scores; another 25 percent had low scores. Nevertheless, there were no dramatic differences between them in terms of their other peripheral measures-carotid ultrasound or AAI. The only way heart disease was detectable in this population was by EBCT."
EBCT is an imaging procedure that measures coronary and aortic calcification, known markers of increased risk for coronary events. Carotid ultrasound, which measures artery wall thickness and arterial blood flow, has been shown to help identify individuals who have plaque build-up in the arteries. An AAI is the systolic blood pressure in the ankle divided by the systolic blood pressure in the arm. When there is an obstruction of blood flow in the leg, the AAI will be less than 1.0. An AAI of less than 0.9 is correlated with disease in other major blood vessels.
The 132 participants from the Cardiovascular Health Study evaluated for this report are now 70-93 years of age, with a mean of 78.2 years. The Cardiovascular Health Study began in 1989 with 5,200 older adults nationwide. Dr. Newman recommends that older adults in this age range might have a low AAI measured if the information can help determine whether drug treatment for their disease is really needed. Dr. Newman said it is uncertain what cut-off to use for the other tests used in this study.
According to Dr. Newman, "EBCT would probably be most useful in people who have no evidence of disease or to confirm known risk factors. I have a woman patient in her early 70s who is very active. She swims every day. She has high cholesterol, about 300 mg/dL, and a sister who had a heart attack at age 60. You would think she'd be at increased risk for cardiovascular disease; but after testing by EBCT we saw almost zero calcifications. She must be 'immune' to arterial build-up. I would not give her drugs to reduce her cholesterol."
Dr. Newman concluded, "About 10 percent of the whole population in this study had minimal to no evidence of atherosclerosis. This is the clearest demonstration yet that you don't have to get cardiovascular disease."