Blood Test May Predict Risks for Heart Patients

But some specialists say study findings won't have immediate impact on practice

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TUESDAY, Jan. 9, 2007 (HealthDay News) -- A blood test for patients with existing heart disease could help predict their future risk for heart attack, stroke or death, a new study suggests.

A biomarker called brain-type natriuretic peptide (BNP) in tandem with prohormone BNP (NT-proBNP) seems to predict future cardiac problems in people with heart disease and may be important warning signs of long-term well-being, the study authors said.

"Doctors are always interested in figuring which of their patients are at the highest risk for developing complications from heart disease," said lead author Dr. Kirsten Bibbins-Domingo, an assistant professor of medicine, epidemiology and biostatistics at the University of California, San Francisco. "It turns out that it's quite challenging to do this."

"We found that when levels of NT-proBNP are elevated, they provide useful information in helping determine who's at highest risk for developing a complication of heart disease -- complications like heart attack, stroke, heart failure or death," Bibbins-Domingo said.

However, several other heart specialists said they weren't ready to embrace the study findings, which are published in the Jan. 10 issue of the Journal of the American Medical Association.

For the study, Bibbins-Domingo and her colleagues assessed the association of plasma NT-proBNP levels with heart attack, stroke, heart failure and death in 987 patients with coronary heart disease. They followed the patients for an average of 3.7 years. During that time, 26.2 percent of the patients had a cardiovascular "event" or died.

The researchers found that increased levels of NT-proBNP at the start of the study were linked with a greater risk of cardiovascular events or death. Patients with the highest levels had a nearly eight-fold increased rate of cardiovascular events or death, compared with people with the lowest NT-proBNP levels. Each increased level of NT-proBNP was linked to a 2.3-fold increased rate of adverse cardiovascular outcomes.

Bibbins-Domingo said this blood test provided data above and beyond other cardiac tests, such as treadmill tests and echocardiograms.

"We anticipate that this blood test would become part of the many tests that physicians use to determine who's at highest risk for developing a complication," she said. "Knowing who is at highest risk will help us to target those who can benefit from the surgical and medical treatments that we know are lifesaving for people with heart disease."

Dr. Marvin A. Konstam is chief of cardiology at the Tufts-New England Medical Center and a professor of medicine at Tufts University School of Medicine, and author of an accompanying editorial in the journal. He doesn't think that knowing NT-proBNP levels will have any impact on the treatment of patients with heart disease.

"I cannot get from this paper a reason for the physician to order this test for a patient with coronary disease," he said. "There is no reason to do a test, if there is no basis for initiating or changing therapy based on that test."

But Konstam does think that, in the future, this or other biomarker tests might replace or add to other cardiac exams in evaluating patients who don't have diagnosed heart disease.

Another expert also agrees that, for patients with heart disease, the NT-proBNP blood test is unnecessary.

"This and other studies have not demonstrated that use of this information can alter management in a way that will improve clinical outcomes," said Dr. Gregg C. Fonarow, the Eliot Corday professor of cardiovascular medicine and science and director of the Ahmanson-UCLA Cardiomyopathy Center and co-director of the University of California, Los Angeles, Preventative Cardiology Program. "It won't alter the clinical approach to these patients."

Fonarow noted that the patients in the study weren't receiving all the recommended care. "The treatment of this group of patients with documented heart disease was well below what is recommended in the national guidelines," he said. "So irrespective of NT-proBNP levels, optimal medical therapy and lifestyle modifications and risk-factor control are necessary for patients with stable coronary disease."

Another study in the same issue of the journal found that taking drugs such as statins and beta-blockers as prescribed after a heart attack is associated with living longer.

In the study, Dr. Jeppe N. Rasmussen of the University of Toronto and colleagues collected data on 31,455 elderly heart-attack survivors. The researchers found that, compared with patients with high levels of adherence to statins, those with intermediate adherence had a 12 percent higher risk of death, and those with the poorest adherence had a 25 percent higher risk.

Rasmussen's group also found similar but less pronounced dose-response adherence to mortality for beta-blockers.

More information

The American Heart Association can tell you more about risks for heart disease.

SOURCES: Kirsten Bibbins-Domingo, Ph.D., M.D., assistant professor of medicine, epidemiology and biostatistics, University of California, San Francisco; Gregg C. Fonarow, M.D., Eliot Corday professor of cardiovascular medicine and science, director, Ahmanson-UCLA Cardiomyopathy Center, co-director, UCLA Preventative Cardiology Program, University of California, Los Angeles; Marvin A. Konstam, M.D., chief of cardiology, Tufts-New England Medical Center, professor of medicine, Tufts University School of Medicine, Boston; Jan. 10, 2007, Journal of the American Medical Association

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