Study finds predictive value of a heart-produced molecule
By Ed Edelson
HealthDay Reporter
TUESDAY, April 5 (HealthDay News) -- A test that measures blood levels of a molecule produced by heart muscle appears to be a strong indicator of future cardiac problems among healthy older people, Danish researchers report.
The test for the molecule, whose jaw-breaking name is "N-amino terminal fragment of the prohormone brain natriuretic peptide" (NT-proBNP), revealed information about the possibility of major heart problems and death "beyond traditional risk factors," the scientists said.
The findings appear in the April 6 issue of the Journal of the American Medical Association.
BNP is a member of a family of molecules called natriuretic peptides that scientists are actively researching as potential measures of heart risk. BNP is produced by the ventricles, the blood-pumping chambers of the heart, under conditions of stress. The Dutch study tested for a fragment of BNP.
BNP tests now are widely used to assess the condition of people admitted to hospitals with life-threatening heart failure. The newly reported study is part of a major effort to determine whether such a test could be used for screening purposes in the general population, along with tests for risk factors such as blood cholesterol and C-reactive protein (CRP), a marker of inflammation.
"We are involved in many studies to expand the use of BNP testing," said Dr. Julie Doyle, medical director of Biosite, a San Diego biotechnology company that marketed the first such test. "We do have ongoing studies to look at its use for screening, but this is not a claim that any manufacturer has made as yet."
The Danish study involved 764 people aged 50 and older, most of whom had no history of cardiovascular problems. A five-year follow-up found that the incidence of death or severe cardiovascular problems was significantly higher for people whose NT-proBNP levels were in the top 20 percent of those tested, the researchers reported.
The results of the new study are "essentially the same" as those of a larger 2004 study of people in the Framingham Heart Study, said Dr. Ramchandran S. Vasan, associate professor of medicine at the Boston University School of Medicine, and a senior Framingham investigator. That study tested for the entire BNP molecule.
"As it stands, this new study adds to the strength of the evidence linking elevated BNP levels to cardiovascular risk," Vasan said. "But I think we need additional data before we suggest that this should be used for screening in the general population."
The two studies shared a general limitation, Vasan said -- they included only older, white people. "We need a much broader sample to answer all the questions," he said.
Some new studies about to be reported could provide answers, Doyle said. "We have a couple of papers that we are looking to submit that have a seven- or eight-year follow-up," she said. "They should be published in the next six or seven months."
Even when those study results become available, "the data are still preliminary at this time about what should be the screening criteria," Doyle said. "The test looks very promising, but at this time we don't have information on that application [screening]."
SOURCES: Julie Doyle, M.D., medical director, Biosite, San Diego, Calif,; Ramchandran S. Vasan, M.D., associate professor of medicine, Boston University School of Medicine; April 6, 2005, Journal of the American Medical Association
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