TUESDAY, Sept. 25, 2001 (HealthDayNews) -- Challenging an idea that has gotten medical and commercial attention in recent years, Harvard researchers say a high level of small LDL cholesterol particles in the bloodstream does not affect the risk of heart disease.
LDL cholesterol is the "bad" cholesterol that forms deposits that narrow and harden arteries, eventually stopping blood flow and causing heart attacks. Some studies have found that small-size, low-density LDL cholesterol is associated with an increased risk of coronary disease.
But researchers, led by Hannia Campos of the Harvard School of Public Health, report in The Journal of the American Medical Association that their study of more than 800 people who have had heart attacks finds no relationship between blood measurements of small LDL particles and the risk of subsequent problems.
In fact, the study finds that large LDL cholesterol particles indicates an increased risk. But it also finds that treatment with a cholesterol-lowering statin drug eliminates that risk, suggesting that total LDL cholesterol levels, rather than the size of LDL particles, is the true risk factor.
Some physicians have used LDL particle size as "a potential index of how you should treat patients," says Dr. Ira J. Goldberg, professor of medicine at the Columbia College of Physicians and Surgeons in New York City and a spokesman for the American Heart Association. "Several different companies that do measurements of small-density LDL have peddled their assays to physicians as state of the art."
Goldberg says he is skeptical of using the small-sized LDL as an indictor of heart disease risk, partly because of a study by Dr. Meier J. Stampfer several years ago that counters that theory. Stampfer also is a member of the Harvard research team that did the latest research. Data on more than 10,000 people in the previous study showed that measuring LDL size added nothing in assessing coronary risk beyond readings of HDL cholesterol (the "good" kind) and triglycerides, another kind of lipid (blood fat), Goldberg says.
Nevertheless, he says, "There is a lot of marketing going on for these kinds of measurements. You can spend up to $500 for a measurement of questionable utility. I've had patients call me up and ask why I'm not measuring small-density LDL. I tell them it doesn't make a difference in treatment."
Dr. Ronald M. Kraus, a senior scientist at the Lawrence Berkeley Laboratory, in California, who has done extensive research on cholesterol and other blood lipids, says the new study is just one part of a very complex picture.
Kraus says one point to consider is that the study "focuses on people who have already had heart disease. It doesn't address the issue of primary prevention."
Kraus has been studying the full array of blood lipids, including LDL cholesterol, HDL cholesterol and triglycerides. He says measuring LDL cholesterol levels alone gives a good reading of coronary risk, but researchers are continually trying to find out whether other blood lipid levels can give a better assessment.
"There is a strong likelihood that we will find individual components that will prove useful as clinical endpoints, but they are not far along in the clinical pipeline," Kraus says.
What To Do
Kraus says LDL cholesterol size may make a difference for some people, but those people have not yet been defined. Treatment with a cholesterol-lowering statin drug should be based on total LDL cholesterol levels, not on LDL size measurements, he says.
A primer on cholesterol and its role in heart disease is available from the the National Heart, Lung, and Blood Institute.
Also, check this site to find out what your cholesterol numbers mean.
