PITTSBURGH, November 10, 1998 — With stunning accuracy, researchers now can definitively predict which women in their 40s and 50s who have no clinical signs of atherosclerosis, or blockage of a blood vessel, will inevitably develop life-threatening heart disease. Presented on Nov. 10 at the 71st American Heart Association meeting in Dallas, the study by University of Pittsburgh clinical researchers will help physicians determine which women should receive more aggressive therapy to avoid heart attack and stroke.
"The results from this prospective study are striking. Heart disease should be absolutely preventable in women whose profiles predict this complication," said Lewis Kuller, M.D., Dr.P.H., principal investigator on this research and university professor and chairman of the department of epidemiology at the University of Pittsburgh’s Graduate School of Public Health. "Ultimately, this work could reduce the physical and financial toll heart disease incurs."
This 15-year study is the first to evaluate the relationship of the heart disease risk factors measured before menopause (premenopause) and the extent of subclinical disease in the coronary arteries and aorta as measured after menopause (postmenopause) by a new and under-utilized technology, electron beam computed tomography (EBCT), otherwise known as ultrafast CT.
"Our findings showed that premenopausal women with traditional high risk factors—high levels of bad cholesterol (LDLc), low levels of good cholesterol (HDLc), high triglycerides, smoking and excess weight—developed disease as evidenced by EBCT," noted Dr. Kuller. "But, importantly, we also found that some premenopausal women without high risk factors had subclinical heart disease postmenopausally when monitored using EBCT," he added.
"EBCT provides an exceptionally accurate picture of subclinical atherosclerosis in the coronary arteries and aorta of postmenopausal women," said Daniel Edmundowicz, M.D., assistant professor of medicine, director of the Electron Beam CT Program and co-director of Preventive Cardiology at the University of Pittsburgh Medical Center’s Cardiovascular Institute. "It is a widely underutilized tool that can be effectively applied in a preventive setting to aid in the management of heart disease, which is the number one killer of women in the United States."
EBCT involves rapidly scanning the beating heart or aorta with x-rays to accurately detect the presence of calcification. Calcium in these arteries indicates the presence of atherosclerosis and can be present long before obstructions occur.
For many years, researchers have known that the incidence of heart disease in women rises sharply as they pass through menopause, a time of complex hormonal and physiological changes. Scientists have described many of the risk factors for heart disease in women. Until now, though, there have been no thorough research analyses combining these known risk factors with results from new tests that detect subtle signs of atherosclerosis before this disease process is discovered using conventional diagnostic measurements, such as stress tests or angiography.
The project involved women who enrolled in the University of Pittsburgh’s Healthy Women Study between 1983 and 1984. For the study, 541 premenopausal women with an average age of 48 were recruited to look at changes in biological and behavioral characteristics as they went from premenopause to postmenopause. Among the baseline measurements taken were: caloric intake and fat as a percentage of total calories, blood samples, blood pressure, levels of total cholesterol, LDLc, HDLc, triglycerides and physical activity.
Of these women, 168 later underwent an EBCT of the heart and aorta to measure calcification. Their mean age was 59, with an average of 11 years between baseline and EBCT. A total of 91 percent of the participants were white, 50 percent had a college education or higher and 28 percent were smokers at the baseline examination. At the time of the EBCT, about 50 percent of the women were on hormone replacement therapy (HRT), 79 percent being on estrogen and progesterone.
"The study findings have allowed us to identify more precisely those women who are at high risk and who may benefit from appropriate early interventions, including changes in lifestyle and the use of appropriate medications," Dr. Edmundowicz remarked. "Through these early interventions, we could potentially reduce the need for more invasive procedures, such as angioplasty and bypass surgery.
Among the findings in the study:
High LDLc levels were a powerful predictor of the extent of coronary and aortic calcification.
Conversely, high HDLc levels resulted in practical immunity to developing significant coronary or aortic coronary calcification.
In combination with high LDLc levels, cigarette smoking among women was a powerful predictor of aortic and coronary calcification.
Women at their 8th postmenopausal exam, many of whom had been on HRT since their first postmenopausal visit, had a lower prevalence of extensive coronary calcification.
Women with high LDLc levels and a low HDLc were at high risk of having high calcium scores, 38 percent, versus only 4 percent for those with low LDLc and high HDLc.
Among smokers with a high LDLc and a low HDLc, 86 percent had evidence of coronary calcification compared to only 17 percent of women who were nonsmokers with a low LDLc and a high HDLc.
This study was supported by grants from the National Institutes of Health.
Please visit the University of Pittsburgh Medical Center's Cardiovascular Institute website for more information on cardiology services and programs. Visit GSPH’s department of epidemiology for more information.