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Blood Transfusions Should be Used in Moderation for Acute Coronary Syndrome

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Duke Health News 919-660-1306

DURHAM, N.C. -- In a study of more than 44,000 patients
being treated for a possible heart attack, cardiologists at the
Duke Clinical Research
Institute
found that while transfusions were associated
with a benefit in some patients, they were associated with harm
in others.

This finding of harm with transfusions in general is not
new, but extends the suggestive evidence from patients in
clinical trials to "real-life" patients seen in the community,
the researchers said.

The findings further suggest that providers should
reconsider their decision-making process about which patients
with acute coronary syndrome, a condition in which patients
show signs of a heart attack, should get transfusions, said the
study's lead investigator, Karen Alexander, M.D. She presented
the study results on Wednesday, Nov. 15, 2006, at the annual
scientific sessions of the American Heart Association, in
Chicago.

The researchers looked at a key blood measure, known as
hematocrit, to see when physicians made the decision to
transfuse blood, and they then compared this transfusion
"decision point" to the health outcomes of the patients.
Hematocrit is a percentage representing the amount of blood
volume that is made up of oxygen-carrying red blood cells. For
males, the normal hematocrit range is 42 percent to 52 percent,
and for women the normal range is 36 percent to 48 percent.

Alexander and colleagues examined how hospitals nationwide
treated patients with acute coronary syndrome with transfusions
based on their lowest recorded hematocrit. These patients
either were anemic when they arrived at the hospital or lost a
significant amount of blood while being treated. In both cases,
physicians typically give the patients blood transfusions.

The researchers found that while transfusions were
beneficial in those whose "nadir" hematocrit, or lowest level,
was less than 24 percent, transfusions were associated with
greater harm in those whose nadir hematocrit was greater than
30 percent, Alexander said. For patients with a hematocrit
between 24 percent and 30 percent, the researchers found that
transfusions were associated with no benefit or no harm.

"Our data suggests that providers may want to reconsider how
they decide which patients should get transfusions," Alexander
said. "Our data confirms no harm or benefit in the medium range
of 24 percent to 30 percent, so in this group of patients, it
might be best to wait and see if the hematocrit drops farther
before making the decision to transfuse. Given the scarcity of
the blood supply, we certainly want to apply this therapy in
those who stand to benefit the most while at the same time
avoiding harm."

In the study, 1,293 patients with a hematocrit of less than
24 percent received a transfusion, while 319 received a
transfusion with a hematocrit greater than 30 percent. In the
middle group, 2,998 received transfusions.

For the analysis, Alexander and colleagues drew on a
national database called CRUSADE, which is coordinated by the
Duke Clinical Research Institute and contains patient
information from more than 400 hospitals. The study was
supported as part of CRUSADE, with additional funding from the
National Institute on Aging.

In total, the researchers identified 44,242 patients treated
for acute coronary syndrome from 2004 to 2005. Of this
population, 10.4 percent had received a blood transfusion, and
3.9 percent of the patients had died, Alexander said.

In transfused patients with a nadir hematocrit of less than
24 percent, the mortality rate was 12 percent, compared with 15
percent for those who did not receive a transfusion, Alexander
said. The mortality rates for patients with a hematocrit of 24
percent to 30 percent were similar whether they were transfused
or not.

The reasons why transfusions may cause harm are unclear,
Alexander said. The red blood cells may be depleted of nitric
oxide, which helps deliver oxygen from the cells to tissues but
which degrades quickly in stored blood. It also is possible
that transfused blood may stimulate an immune response that
exacerbates already existing heart disease. A randomized study
is needed to clarify the safety and benefit of transfusion,
just as other therapeutic interventions for acute coronary
syndromes are tested, Alexander said.

Other researchers who participated in the study were Anita
Chen, Kristin Newby, Nancy Allen-LaPointe, E. Magnus Ohman,
Matthew Roe, William Boden and Eric Peterson.

CRUSADE is coordinated by the Duke Clinical Research
Institute. It is funded by Schering-Plough Corp., with
additional funding from the Bristol-Meyers Squibb/Sanofi
Pharmaceuticals Partnership and Millennium Pharmaceuticals.
Alexander has no financial interest in the sponsors of
CRUSADE.

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