Monitoring Protein Didn't Improve Heart Failure Outcomes
TUESDAY Jan. 27, 2009 -- Using the biomarker molecule known as brain natriuretic peptide (BNP) to guide treatment for older people with chronic heart failure did not improve the clinical outcome in most cases in a Swiss study.
There have been conflicting reports about the value of monitoring blood levels of BNP, a protein produced by stressed heart cells, for better management of heart failure. For example, a French study reported in 2007 found that BNP monitoring reduced deaths and hospitalizations in a 115-participant trial.
But the new study, published in the Jan. 28 issue of the Journal of the American Medical Association by physicians at University Hospital Basel, found that BNP-monitored therapy guidance generally did not improve 18-month survival or quality of life over conventional symptom-guided therapy.
All the people in the trial were 60 or older. All were hospitalized for heart failure, and all had BNP blood levels at least double the normal readings.
Some improvement over symptom-guided treatment was found with BNP-guided therapy for those 60 to 74, but not for those aged 75 and older.
Despite those results, BNP measurement does have a role in diagnosis and treatment of heart failure, said Dr. Gregg C. Fonarow, a professor of cardiovascular medicine at the University of California, Los Angeles.
"It is very useful in diagnosing heart failure," Fonarow said. "When someone shows up in an emergency room, BNP testing will help determine whether the cause is heart failure. Whether serial testing will improve clinical outcome remains unknown and is worthy of further study."
The Swiss trial is not definitive, because it was relatively small, with only 499 participants, Fonarow said. "All the studies to date have been rather small," he said. "It is certainly worthwhile to consider further clinical trials of serial BNP testing to guide treatment."
The finding of benefit for persons aged 60 to 74 "really needs to be confirmed by other studies," Fonarow said.
BNP testing to guide heart failure treatment can be used if its role is clearly understood, said Dr. Lavoisier J. Cardozo, a professor of medicine at Wayne State University, who said he uses it routinely.
"This study says that BNP tests can tell you stuff, and clinical examinations can tell you stuff, and you can evaluate one against the other," Cardozo said.
Using clinical evaluation of symptoms to guide treatment is better in older patients, because BNP levels go up with age, Cardozo said. "Normal changes in the heart with aging confound the issue," he said. "As you age normally, you can get heart tissue trauma and that can lead to high BNP levels. If you just read the number, you tend to overtreat. We do use BNP on every patient with heart failure, and we remember that the BNP numbers for them will be slightly higher."
While BNP testing is undoubtedly useful in helping diagnose heart failure, "I think the jury is still out on its use in guiding therapy in chronic cases," said Dr. Christopher O'Connor, a professor of medicine at Duke University and director of the Duke Heart Center who co-authored an accompanying editorial.
"The trials to date have been relatively modest in statistical power," O'Connor said. "The results of this study are encouraging and do warrant a definitive, large-scale trial that I hope will be done. I think there would be a lot of enthusiasm for such a trial."
But caution is needed in using BNP tests to guide therapy in the oldest people, O'Connor noted. "Physicians might be encouraged to be too aggressive in drug therapy to reduce BNP levels, which could result in side effects and complications with drugs," he said.
Heart failure and its treatment are explained by the U.S. National Library of Medicine.
Posted: January 2009