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 treatment."
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 medic
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