DALLAS, July 25, 2000 -- Teenagers and young adults who have risk factors for heart disease have fatty plaques in their arteries that indicate varying stages of atherosclerosis -- from the earliest signs of blockages to the more dangerous advanced stages -- according to a study in today's Circulation: Journal of the American Heart Association.
"The major strategy to prevent heart disease has been controlling risk factors such as smoking, high blood pressure, and high cholesterol," says the study's lead author Henry C. McGill, Jr., M.D., of the Southwest Foundation for Biomedical Research in San Antonio, Texas. "However, there is still much controversy over the age at which such efforts should begin.
"If our results hold true for larger populations, one in five men between the ages of 30 and 34 has some significant damage to his heart arteries that has probably developed over the past 20 years due to one or more risk factors for heart disease," he says. "This would indicate the need to tailor prevention messages to younger people."
McGill and his colleagues studied portions of left coronary arteries -- one of the pair of large blood vessels that supply blood to the heart -- taken from the autopsies of 760 men and women ages 15-34 who had died from an accident, homicide, or suicide. They measured the amount and type of fatty deposits in the arteries and determined the heart disease risk factors -- such as smoking, high blood pressure, obesity, and high cholesterol -- for each person. The researchers report that individuals who had high blood levels of low-density lipoproteins, or LDL cholesterol (the "bad" cholesterol) were about two-and-a-half times more likely to have "advanced" plaque blockages in their heart arteries than people who did not have high LDL levels.
Advanced grade plaques are deposits on blood vessel walls that have a fibrous cap and a soft, fatty core. These plaques are more likely to rupture, causing a blood clot that would block blood flow, thus leading to a heart attack or sudden death.
"It's not too surprising that high blood cholesterol is associated with the advanced plaques," McGill says. "But to show that it has an effect as early as age 15 gives strong support to the idea that nutritional guidelines for the prevention of heart disease should be recommended for children as well as adults."
McGill also says that obesity seems to have a very strong effect on the development of atherosclerosis regardless of an individual's cholesterol levels or other risk factors. The young people who were obese were over two-and-a-half times more likely to have advanced grade plaques than those who were not obese.
Researchers found that about 2 percent of the 15- to 19-year-old men and 20 percent of 30- to 34-year-old men in the study had advanced plaques. Researchers did not find advanced plaques in women aged 15 to 19, but they did find such plaques in 8 percent of 30- to 34-year-old women.
"Notice that the difference between percentages of men and women between age 30 and 34 with advanced plaques is similar to the difference in rates of heart disease between men and pre-menopausal women in middle age," McGill says. "This similarity indicates that early risk factors may be a significant predictor of a person's chance of developing heart disease later in life." In addition to certain risk factors contributing to advanced plaques, risk factors such as low blood levels of high-density lipoproteins, or HDL cholesterol (the "good" cholesterol) and smoking increased the likelihood of "intermediate" grade plaques, which indicate the earliest stages of atherosclerosis.
"In younger people smoking is just starting to have an effect on the coronary arteries, but this doesn't let smoking off the hook as a serious contributor to atherosclerosis," McGill says. He says other studies have shown that smoking has a greater effect on the aorta, the body's largest artery, than on the coronary arteries.
Co-authors of the study are C. Alex McMahan, Ph.D.; Arthur W. Zieske, M.D.; Richard E. Tracy, M.D.; Gray T. Malcom, Ph.D.; Edward E. Herderick, B.S.; and Jack P. Strong, M.D.
Media Advisory: Dr. McGill can be reached by phone at (210) 258-9408; or by email at hmcgill@icarus.sfbr.org (Please do not publish numbers or email addresses.)
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