WASHINGTON -- A long-term study indicates high levels of a certain protein in the blood are associated with an increased risk of heart attack and stroke, giving doctors another way to assess a person's cardiovascular health.
The government-sponsored study in Framingham, Mass., found that people with elevated amounts of fibrinogen, a protein involved in the blood clotting process, had more heart attacks and strokes than those with lower levels.
'In the Framingham study, fibrinogen level seems to rank high among the predisposing factors for cardiovascular disease,' Dr. William Kannel of the Boston University Medical Center said in a report Thursday in the Journal of the American Medical Association.
Dr. William Castelli, director of the Framingham study for the National Heart, Lung and Blood Institute, said the finding adds a 'whole new dimension to this heart attack issue.'
'I think it opens a whole new class of risk factors,' he said in a telephone interview.
The Framingham study has followed more than 5,000 people since 1948 and has shown that such things as high blood cholesterollevels, high blood pressure, smoking and excess weight are involved in cardiovascular disease.
Scientists added measurements of fibrinogen to the study in 1968 because of its suspected importance.
Heart attacks are America's No. 1 killer, claiming more than 500,000 lives annually. They occur when blood is cut off from reaching the heart, and it is generally agreed that a clot is needed to make the final blockage in arteries already clogged by fatty deposits, Castelli said.
The study found a significant association between elevated amounts of fibrinogen in the blood of men and heart disease and a 'marginally significant' link between the protein and heart disease in women.
A similar trend was seen in men for stroke, in which blood flow is cut off to part of the brain, but there was no clear trend for women, the report said.
Castelli noted many laboratories have the capability to determine a person's fibrinogen level and he recommended such tests for people already considered at high risk for a heart attack or stroke.
The report cited some evidence that quitting smoking reduces fibrinogen levels, and Castelli said people who eat high-fat and high-cholesterol diets tend to have higher amounts of fibrinogen in their blood. There is no proven way to reduce fibrinogen, however.
Nevertheless, if a doctor finds a patient has high levels of the protein, the doctor might be prompted to become more aggressive in trying to reduce the person's other known risk factors, Castelli said.
'I think we're starting down a whole new road,' he asserted. 'It's the road to 'How do I keep myself from clotting to death?' We're going to have to learn how to do that. I think we have some clues.'
