MONDAY, Jan. 9 (HealthDay News) -- The anticoagulant Pradaxa
(dabigatran) is associated with a small increase in the risk of
heart attack, a new review finds.
Researchers from the Cleveland Clinic in Ohio looked at seven
trials involving Pradaxa that included more than 30,000 patients.
This process, called a meta-analysis, uses data from published
clinical trials to tease out a pattern that might not show up in a
The researchers found Pradaxa was associated with an increased
risk of heart attack or acute coronary syndrome (heart attack or
angina), compared with two other commonly used blood thinners,
warfarin (Coumadin, Jantoven) and enoxaparin (Lovenox).
Among those taking Pradaxa, 1.19 percent had a heart attack or
suffered from acute coronary syndrome compared with 0.79 percent of
those taking either of the other drugs, they noted.
Although there was a 33 percent increase in relative risk for a
heart attack among those taking Pradaxa, the absolute increased
risk -- that is, the added risk for any one individual of having a
heart attack if on Pradaxa -- was 0.27 percent, researchers
Pradaxa was approved by the U.S. Food and Drug Administration in
October 2010 for people with a common heart rhythm problem called
atrial fibrillation. People with atrial fibrillation are at a
higher risk for stroke and are often prescribed medication to
Pradaxa is often prescribed as an alternative to warfarin, a
medication that has been used for a long time but which can raise
the risk of bleeding and is difficult to dose properly.
Pradaxa is also used to prevent blood clots in people who've had
joint replacement surgery.
"For persons with atrial fibrillation, dabigatran has a favorable benefit-risk profile, but for other uses the risk of heart attack has to be taken into account," said lead researcher Dr. Ken Uchino, director of the Vascular Neurology Fellowship Training Program at the Cleveland Clinic.
The report was published in the Jan. 9 online edition of the
Archives of Internal Medicine.
In the large study that led to the approval of Pradaxa, there
was a suggestion that Pradaxa might be associated with an increased
risk of heart attacks, Uchino explained.
However, the drug's benefit for patients with atrial
fibrillation outweighs the risk, he said.
"The increase of [heart attack] risk associated with dabigatran is small, and the benefit in prevention of stroke among persons with atrial fibrillation is greater," Uchino said.
Why Pradaxa is associated with an increased heart attack risk
isn't clear, they say. It's possible Pradaxa doesn't increase heart
attack risk directly, but it may not be as effective as warfarin
and aspirin in preventing heart attacks, he added.
Dr. John Smith, senior vice president for clinical development
and medical affairs at Boehringer Ingelheim, the makers of Pradaxa,
said that "we don't agree with the conclusion and the method used
for this meta-analysis. Based on all the data, we conclude that
heart attack is not an adverse consequence of Pradaxa
Another expert said that the risk of heart attack does not
outweigh the benefits of the drug, especially taking the risk of
serious bleeding with warfarin into account.
"I would be cautious about this meta-analysis. It doesn't convince me," Dr. William O'Neill, a professor of cardiology and executive dean for clinical affairs at the University of Miami School of Medicine, said. "I am unimpressed by the data."
Warfarin, O'Neill added, "is a pretty lousy drug."
Although he estimated about one in 10 patients can't tolerate
Pradaxa because of severe gastrointestinal side effects, "you don't
have to monitor it the way you have to with warfarin. It's a big
improvement over warfarin."
Dr. Jeremy Jacobs, a lecturer in geriatric medicine at Hebrew
University Medical Center in Jerusalem and author of an
accompanying editorial, said the study shows the importance of
continuing to track new drugs after they've been approved and
placed on the market.
"The dabigatran debate is a good example which raises issues concerning post-marketing surveillance, and pharmaco-vigilance," Jacobs said. "Who takes responsibility? Industry? Independent researchers? National bodies?"
"I personally tend to favor the latter, since the stakes are very high for new drugs, and it is difficult for industry-backed research to overcome conflicts of interest that inevitably arise," he added.
As far as dabigatran is concerned, Jacobs said that physicians
should be cautious, especially when prescribing it to patients with
known heart disease. The issue will only be clarified as more data
about the risk accumulates and how it measures up against the
dangers of bleeding posed by warfarin, he said.
For more on Pradaxa, visit the
U.S. National Library of Medicine.
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