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MONDAY, June 23, 2003 (HealthDayNews) -- Doctors have known that people with high levels of a blood protein tied to vessel inflammation face an increased risk of heart attacks, strokes and other cardiovascular problems. But whether the substance is an independent risk factor for these episodes or merely a reflection of narrowed and crumbling arteries hasn't been entirely clear.
New research now suggests that the molecule, called C-reactive protein (CRP), is indeed its own oddsmaker.
While levels of the protein typically rise with the thickness of the clogged arteries, people with elevated CRP are at increased risk of strokes regardless of the severity of the narrowing.
CRP "appeared much less important in the absence of atherosclerosis than in the presence of atherosclerosis," says Dr. Mary Cushman, a blood specialist at the University of Vermont in Burlington and leader of the research.
Still, "only a small portion of the association of CRP with stroke can be attributed to" how much narrowing there is in the arteries, Cushman adds.
The problem is what to do with the information. The American Heart Association advises doctors to test for CRP levels in people considered at moderate risk of heart attacks or strokes. A finding of elevated CRP might prompt more aggressive treatment to reduce that risk, the group says, but there's no evidence that targeting the protein itself will do so.
"If a patient has higher CRP, you get aggressive about lowering their global risk" of cardiovascular problems, says Dr. Richard Stein, director of medicine at Beth Israel Medical Center's Singer Division in New York City and a spokesman for the heart association.
The cholesterol-fighting drugs known as statins have been shown to lower CRP by about 25 percent or so, Stein says. However, it's not clear that that effect reduces cardiovascular trouble or increases survival.
The latest study appears in the June 23 issue of the journal Circulation. Cushman and her colleagues tracked more than 5,400 men and women aged 65 and up, none of whom had suffered a stroke or heart attack before entering the study.
Over the 10 years of the study, there were 469 ischemic strokes -- those involving the loss of blood to the brain caused by a clot in the vessels that feed the organ -- among those who were tracked.
Smoking habits, diabetes, cholesterol, blood pressure, and other factors influence the risk of stroke. But after considering these, people whose CRP was in the top fourth had a 60 percent higher risk of stroke than those in the bottom quarter.
The increase fell to about 50 percent when Cushman's group accounted for the thickness of the carotid artery wall -- a decline, but not a very substantial one, she says.
More information
Visit the American Heart Association or the National Library of Medicine for more on CRP.
