The finding, presented at a recent medical meeting here, adds to a growing number of studies that bolster the idea of testing for lipoproteins, the tiny spheres that carry cholesterol in the blood and that penetrate artery walls, causing heart disease.
Lipoproteins have been compared with garbage trucks that carry the debris (cholesterol) into the dump (the space inside artery walls).
Small lipoprotein particles can more easily enter artery walls than large ones. They also are more likely to cause damage, primarily through an oxidative process that leads to plaque buildup, inflammation, heart disease and, eventually, a heart attack.
Some of the same things that improve cholesterol levels — diet, exercise and statin drugs — also improve lipoproteins.
Although lipoprotein testing is gaining acceptance, major health organizations such as the American Heart Association and the National Institutes of Health have yet to recommend it.
This time, researchers with Tufts University School of Medicine used blood samples from 3,227 middle-age men and women taking part in the ongoing Framingham Heart Offspring Study.
Over an eight-year period, measuring the number of lipoprotein particles proved to be a better predictor of heart disease risk than traditional LDL cholesterol, the bad kind.
``I think we are slowly building a case,'' said lead author Ernst Schaefer, a Tufts researcher and chief of the lipid metabolism laboratory and senior scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging. ``It (lipoprotein) is a very important predictor.''
However, Schaefer said that while the number of lipoprotein particles is a better measure of heart disease risk than LDL cholesterol, it is not hugely better.
And the matter may come down to cost. Lipoprotein testing costs between $60 and $100. Cholesterol testing is a fraction of that.
Some cardiologists, including those at the University of Wisconsin-Madison, already have added lipoprotein testing to the blood tests done on their patients.
James Stein, a UW cardiologist and associate professor of medicine, said the new research comes from a highly respected study and group of researchers.
``What's nice about this is it's big and they have follow-up,'' Stein said.
``It just continues to make the case stronger. Eventually, it comes to the point where the weight of the evidence is so strong that no one can ignore it.''
In some patients, lipoprotein testing, no doubt, is useful, said Sidney Smith, a professor of medicine and director of the Center for Cardiovascular Science in Medicine at the University of North Carolina, Chapel Hill. And the new study bolsters that, he said.
``I think this is important information,'' he said.
However, Smith said that ultimately it will have to be showed that improving lipoprotein levels results in fewer heart attacks and strokes.
That could take studies with thousands of patients over the course of years.
The study was funded by LipoScience, a Raleigh, N.C., company that does lipoprotein testing, including the testing used in the Tufts study.
It was presented last week at the American Heart Association's Scientific Sessions
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