by David Dorfman (American Council on Science and Health )

Despite its strong association with coronary heart disease (CHD), lowering cholesterol levels alone is not enough to protect arteries from fatty deposits which can lead to heart attacks. Non-lipid factors, namely smoking, high blood pressure, obesity, and diabetes, also put people at risk for developing atherosclerosis, according to a study in the March 20, 2001 issue of Circulation, a journal of the American Heart Association. Atherosclerosis occurs when fatty deposits accumulate in the walls of arteries, restricting blood flow. When these deposits develop in the arteries of the heart, they cause CHD and can result in a heart attack.

Atherosclerosis develops in two stages: the first stage is the accumulation of fat filled cells in the inner lining of the artery, called fatty streaks. The second is a thick plaque which covers a fatty core and gradually narrows the artery, restricting blood flow. Unfavorable cholesterol profiles are the most commonly known cause of atherosclerosis.

In a press release for the study, lead author Henry C. McGill Jr., MD, of the University of Texas Health Center at San Antonio says "the strong association between cholesterol levels and heart disease may have given some the false idea that other risk factors are unimportant. We've probably under-emphasized non-lipid risk factors."

McGill and colleagues examined the effects of risk factors unrelated to cholesterol on the development of atherosclerosis as part of the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) project. To do this they collected data from autopsies of 856 young men and women aged 15 to 34 who had normal cholesterol profiles. All the subjects had died in accidents, homicides, or suicides between 1987 and 1994.

Pathologists dissected the abdominal portion of the aorta, the main artery leaving the heart, as well as the right coronary artery (RCA), which delivers blood to the heart muscle. The pathologists looked for the presence and progression of fatty streaks and plaques within these vessels. The results of these dissections were then correlated with potential risk factors for atherosclerosis including sex, smoking status, high blood pressure, obesity, and diabetes.

The researchers found the most pronounced effects of smoking in the abdominal aorta. Those in the study who smoked had more extensive fatty streaks and three times the extent of plaques in the abdominal aorta as non-smokers. This finding is consistent with the established association of smoking with abdominal aortic aneurysms (bulging arterial walls).

Compared to non-obese males, obese men had more fatty streaks and twice the extent of plaques in the RCA. Obesity did not affect atherosclerosis in women. Overall, the results indicate a more rapid progression of atherosclerosis in young men than young women. High blood pressure did not affect fatty streaks, but was associated with more extensive RCA plaques, particularly among black men and women.

High blood sugar (an indicator of diabetes) was associated with more extensive fatty streaks in the RCA.

In summary, risk factors unrelated to cholesterol, namely smoking, high blood pressure, obesity, sex, and diabetes, accelerated the development of atherosclerosis in young men and women with normal cholesterol profiles. According to the authors, this means "an unfavorable lipoprotein [cholesterol] profile is not a necessary condition for the progression of atherosclerosis in young people."

They add "the high prevalence of non-lipid risk factors indicates considerable potential to affect early atherosclerosis and subsequent CHD by modifying these risk factors."

In a press release for the study, McGill advises that "parents shouldn't wait until more than one risk factor is present before modifying a child's lifestyle. Your children's health in middle age depends on how you raise them today."
(Date Published: 5/11/01)


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