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Blood test can accurately diagnose
heart failure in emergency patients
Measuring protein level provides
accurate assessment for patients with shortness of breath
BOSTON - April 11, 2005 - A new blood test that measures
a particular marker of cardiac distress can markedly improve the
ability to diagnose or exclude congestive heart failure in patients
with shortness of breath who come to hospital emergency departments.
The report from researchers at Massachusetts General Hospital (MGH)
finds that measuring levels of a protein called NT-proBNP was significantly
better at identifying heart failure than was standard clinical evaluation.
The report will appear in the April 15 issue of the American
Journal of Cardiology and has been released online prior to
print publication.
"We found that testing with the NT-proBNP assay was an extremely
accurate way to identify or exclude heart failure in patients with
shortness of breath," says James Januzzi Jr., MD, of the MGH
Cardiology Division, the paper's lead author. "Importantly,
we also found that the very best results came from combining the
results of this very sensitive and specific blood test with the
logic and wisdom of a good emergency physician, which gave the optimal
balance between biologic data and clinical judgement."
Congestive heart failure, which occurs when an impaired heart muscle
cannot pump blood efficiently, is a growing health problem and major
cause of cardiac death. The diagnosis of heart failure may be difficult
to make because its typical symptoms can overlap with those of other
conditions. Missing a heart failure diagnosis can put patients at
high risk of serious problems, including death, but overdiagnosis
may lead patients to receive unnecessary treatment.
"To date, the way physicians have traditionally evaluated potential
heart failure patients has been rather random, with some receiving
a physical examination and medical history while others also get
expensive and time-consuming procedures," Januzzi says. "Having
a widely-available, accurate, and cost-effective diagnostic method
would be of extraordinary value."
Proteins called natriuretic peptides are produced when the cardiac
muscle is under stress. The role of testing for these proteins in
several forms of cardiovascular disease has been the subject of
intense recent study. In 2002, the newest generation of natriuretic
peptide assays became available, and soon thereafter the current
investigation - called the PRIDE study - was launched to determine
the usefulness of a test for NT-proBNP in evaluating emergency patients.
At the time of its launch, the PRIDE study was the first prospective
American trial of NT-proBNP and the largest such study to study
the test in patients with shortness of breath.
About 600 patients who came to the MGH Emergency Department with
shortness of breath were enrolled in the study. In addition to standard
evaluation of symptoms, a blood sample was drawn for NT-proBNP measurement.
After the emergency assessment was completed, the attending physicians
were asked to estimate the likelihood that the patients' symptoms
were caused by heart failure, based on all available information
except the NT-proBNP assay. For patients admitted to the hospital,
the entire record of their stay was included in the study data.
Sixty days after the original emergency visit, the researchers followed
up with each patient, contacting them personally and reviewing their
records to identify any subsequent clinical events. Participation
in the study in no way changed the care or treatment the patients
received.
To determine the diagnoses for this study, cardiologists not involved
in the patients' care reviewed all the participants' relevant hospital
records from the initial emergency visit through the 60-day follow
up. In assigning the final diagnosis - either acute heart failure
or some other cause for shortness of breath - these physicians also
did not have access to the NT-proBNP results.
When they reviewed NT-proBNP levels, the researchers found that
the protein's concentrations were significantly higher in patients
eventually diagnosed with heart failure and highest in those with
most severe symptoms. For identifying heart failure in these emergency
patients, the test alone was significantly more accurate than was
the physicians' original likelihood assessment, but a combination
of NT-proBNP levels and physician judgement produced the most accurate
method of diagnosis.
"We also identified specific NT-proBNP levels above which the
diagnosis of heart failure is clear and below which the symptoms
are definitely not cardiac-related," Januzzi says. "So
we've shown that this test not only can confidently exclude the
presence of congestive heart failure, which other studies have examined,
but can confirm that diagnosis as well. NT-proBNP performed exceptionally
well and confirms the value of the natriuretic peptide class of
cardiac biomarkers as a whole. We believe NT-proBNP testing should
now become a routine component of evaluation for patients with shortness
of breath in emergency department settings." Januzzi is an
assistant professor of Medicine at Harvard Medical School.
Co-authors of the study - all from the MGH - are Carlos Camargo,
MD, PhD; Saif Anwaruddin, MD; Aaron Baggish, MD; Annabel Chen, MD;
Daniel Krauser, MD; Roderick Tung, MD; Renee Cameron, MS; Tobias
Nagurney, MD; Claudia Chae, MD, MPH; Donald Lloyd-Jones, MD, ScM;
David Brown, MD; Stacy Foran-Melanson, MD, PhD; Patrick Sluss, MD,
PhD; Elizabeth Lee-Lewandrowski, PhD, MPH; and Kent Lewandrowski,
MD. The study was supported by a grant from Roche Diagnostics, which
manufacturers the NT-proBNP assay studied.
Massachusetts General Hospital, established in 1811, is the original
and largest teaching hospital of Harvard Medical School. The MGH
conducts the largest hospital-based research program in the United
States, with an annual research budget of more than $450 million
and major research centers in AIDS, cardiovascular research, cancer,
cutaneous biology, medical imaging, neurodegenerative disorders,
transplantation biology and photomedicine. In 1994, MGH and Brigham
and Women's Hospital joined to form Partners HealthCare System,
an integrated health care delivery system comprising the two academic
medical centers, specialty and community hospitals, a network of
physician groups, and nonacute and home health services.
Media Contact: Sue
McGreevey, MGH Public Affairs
Physician Referral Service: 1-800-388-4644
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