Testing Elders' Blood for Heart Disease

High Levels of a Protein Could Predict Death, Heart Trouble

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April 5, 2005 -- A blood test could help predict heart disease in older adults even after taking into account more traditional risk factors.

The key blood chemical may change with age, according to a new study in The Journal of the American Medical Association.

Could the findings lead to a new heart disease blood test for senior citizens? Perhaps, but more work is needed first, write the researchers, who included Caroline Kistorp, MD, of Denmark's Frederiksburg University Hospital.

Heart disease is a leading cause of death for U.S. men and women. It hits older adults especially hard.

About 84% of heart disease deaths occur in people aged 65 and older, according to the American Heart Association (AHA). Similarly, about 88% of stroke deaths strike people aged 65 or older, says the AHA.

Probing the Blood to Predict Heart Trouble

In middle-aged people, high blood levels of the inflammatory marker known as C-reactive protein have been linked to heart problems. But a few decades from now, another blood marker may be more important, say Kistorp and colleagues.

For adults aged 50-89, another protein was a better predictor of heart disease than C-reactive protein, says Kistorp's study.

The protein studied was called NT-proBNP. Besides beating C-reactive protein as a heart disease predictor, it also surpassed another marker of heart disease -- urine protein levels.

Results came from 626 people in Copenhagen. Virtually all were white, which is one reason why Kistorp's team says further, more diverse tests are needed.

At the study's start, none had heart or kidney failure, and 537 had no history of heart disease. The participants gave blood and urine samples for screening and were followed for five years.

During the study, 94 people died of any cause and 65 had a first major cardiovascular "event." Those included a nonfatal heart attack, stroke, heart failure, chest pain (unstable angina), coronary heart disease, and transient ischemic attacks (ministroke).

Participants with the highest blood levels of NT-proBNP were at higher risk of heart disease deaths and heart problems, including heart attack and stroke, than those with the lowest levels.

The increased risk of heart disease continued to exist even after the researchers took into account traditional risk factors for heart disease, such as smoking and being overweight.


Earlier Findings

In 2003, other researchers reported that another inflammatory marker, interleukin-6, was a better predictor of heart disease, stroke, and heart failure in a three-year study of 2,225 people in their 70s.

That study didn't cover the type of protein studied here, but the researchers said they thought C-reactive protein might not be as closely tied to cardiovascular events in older people. That study appeared in the November 2003 edition of the journal Circulation.

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SOURCES: Kistorp, C. The Journal of the American Medical Association, April 2, 2005; vol 293: pp 1609-1616. News release, JAMA/Archives. American Heart Association. WebMD Medical Reference from Healthwise: "Transient Ischemic Attack (TIA) -- Topic Overview." Cesari, M. Circulation, Nov. 2003; vol 108: pp 2317-2322. News release, American Heart Association (2003).
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