Protein Linked to Heart-Attack Risk

2 April 1997 8:00 pm

Elevated levels of a protein produced in response to infection and injury correspond to a higher risk of heart attacks and stroke in men. The finding, reported in tomorrow's New England Journal of Medicine, may help doctors spot high-risk candidates among apparently healthy patients and hints that anti-inflammatory drugs may be useful in treating cardiovascular disease.

A research team at Brigham and Women's Hospital in Boston and the University of Vermont, Burlington, measured levels of C-reactive protein in blood samples from 1086 participants in the Physicians' Health Study--an 8-year trial, which ended in 1995, that examined the effects of aspirin and beta carotene on cardiovascular disease in more than 22,000 men. Although C-reactive protein levels in all the men were within a range considered normal, the average concentrations were higher in subjects who eventually suffered a heart attack or a stroke. Men with C-reactive protein values in the top 25% had triple the risk of a heart attack, and double the risk of a stroke, compared with those with values in the lowest quartile. The researchers also found that aspirin, which was shown in the trial to help ward off cardiovascular disease, made the most difference in subjects with relatively high C-reactive protein levels and gave almost no benefit to those with lower protein levels.

The finding is very exciting, says cardiologist Attilio Maseri of the Catholic University of the Sacred Heart in Rome. Researchers have been studying the details of the familiar risk factors--cholesterol levels and blood-clotting factors--for decades. "This is the first time something different has been shown to have predictive value in the long term," he says. "It opens up a whole new line of research."

Still, the researchers do not know whether C-reactive protein--a molecule long used to diagnose acute infections--plays a role in heart attacks and strokes or whether it simply flags another biochemical breakdown. And more studies are needed to sort out whether aspirin helps prevent heart attacks and strokes by reducing inflammation or by some other mechanism. Says co-author Mary Cushman of the University of Vermont, Burlington, the study really "raises more questions than it answers."

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