Study flags risk of heart attack, ACS in Pradaxa patients

Another blow to Pradaxa's prospects: The Boehringer Ingelheim blood thinner has been associated with an increased risk of heart attack. In a new study, Cleveland Clinic researchers found that Pradaxa increased the risk of acute coronary syndrome and heart attack about one-third.

As The Wall Street Journal reports, the data could cause doctors to think twice about switching their warfarin patients to Pradaxa or another new, alternative blood thinner such as Bristol-Myers Squibb ($BMY) and Pfizer's ($PFE) Eliquis or Bayer's Xarelto. But the increased risk found in the new study was small on an absolute basis, and Pradaxa has proven effective at reducing strokes. "We don't want to push the panic button," Cleveland Clinic's cardiology chief Steven Nissen told the Journal. "The stroke benefit is well established."

The new analysis comprised more than 30,000 patients, comparing Pradaxa users with patients using another blood thinner or placebo. In the Archives of Internal Medicine study, researchers concluded that Pradaxa was "significantly associated with a higher risk" of ACS and heart attacks. Doctors should weigh "the potential of these serious harmful cardiovascular effects" when prescribing, the researchers said (as quoted by Bloomberg).

Not surprisingly, Boehringer takes issue with the study, pointing to another look at the 18,000-patient trial that compared Pradaxa with the previous standard of therapy for stroke prevention in atrial fibrillation patients, warfarin. The analysis, published in the journal Circulation, found an increase in heart attacks, but that increase wasn't statistically significant, WSJ says.

The heart attack and ACS questions come as the FDA and European regulators have been looking at Pradaxa's potential to cause serious bleeding. Late last year, Boehringer warned that patients should have their kidney function tested, because renal impairment might increase the risk of bleeding. The European Medicines Agency, meanwhile, asked for updated product labeling to reflect the kidney-function testing; even in light of reports of 256 deaths from bleeding in Pradaxa patients, the EMA concluded that the new labeling would "adequately manage" bleeding risk.

Already conducting a safety review of bleeding risks, the FDA says it's now planning to look at the heart-attack data. The agency says it will use a variety of data to compare heart attack numbers in Pradaxa patients and warfarin patients.

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