People taking dabigatran, a recently approved blood-thinning drug, may be at higher risk of having a heart attack compared with patients who stick to the old and proven warfarin, according to recent research.
When the US Food and Drug Administration (FDA) unanimously approved dabigatran for use in 2010, it was the first new anticoagulant drug in 50 years. The preparation sold under the name Pradaxa takes about 500. to help prevent blood clots that could lead to a stroke. The drug is intended mainly for patients with atrial fibrillation, who are particularly vulnerable to a stroke, but also for people waiting for surgery, e.g. joint replacement, because it prevents the formation of blood clots.
Unfortunately, dabigatran’s triumphant entry into the market is overshadowed by doubts about its impact on the heart. Several clinical trials have shown that the new drug slightly increases the risk of a heart attack compared with warfarin, but re-analyzes commissioned by the FDA show that the difference is statistically insignificant.
The latest report by Dr. Ken Uchino, a neurologist at the Cleveland Clinic in Ohio, published online in early January in the Archives of Internal Medicine tries to explain the situation. The report summarizes the results of seven studies involving a total of 30 patients, which focused on comparing dabigatran with warfarin, enoxaparin (a solution for injection to prevent blood clotting) or placebo. Most of the data comes from the same clinical trials that previously served as the basis for approving dabigatran, the so-called RE-LY (Randomized Evaluation of Long term anticoagulant therapy – randomized trial of long-term anticoagulant therapy).
Although the frequency of heart attacks or angina (chest pain caused by hypoxia of the heart) increased by 33%. among patients taking dabigatran, the risk remains low: among 20 of patients taking this drug, there were only 237 cases related to heart disease – this is 1,19%. For comparison, in the groups taking other drugs or placebo, the risk was 0,79%, emphasizes Uchino.
What makes dabigatran patients more at risk than those treated with warfarin is not known yet, said Dr. Stuart J. Connolly, director of cardiology at McMaster University in Canada, who participated in the analysis of the RE-LY study. Perhaps taking warfarin is somehow beneficial for the heart, the researcher says.
“When we warn that people taking dabigatran are at greater risk of having a heart attack than those taking warfarin, we are not suggesting that dabigatran causes a heart attack,” explains Connolly. This means – and the evidence supports this – that compared to dabigatran, warfarin reduces the frequency of heart attacks.
However, according to Dr Jeremy M. Jacobs of the Hadassah Hebrew University medical center in Jerusalem, doctors should moderate their enthusiasm for dabigatran a bit until additional research is done to clearly determine the potential risk of a heart attack. “Patients with known ischemic heart disease require special care,” says Jacobs.
Experience has taught physicians that it is impossible to establish the full range of effects of a new formulation until the drug is widely used – sometimes years after the FDA has approved it for use, notes Jacobs. For example, the painkiller Vioxx, which was withdrawn from the market in 2004, was on the market for five years before it became clear that its use increased the risk of heart attack and stroke.
The potential link between dabigatran use and heart attack has yet to be established. The authors of the RE-LY study, which only involved people with atrial fibrillation, found no significant increase in the risk of heart disease among patients taking dabigatran.
The study found that dabigatran was superior to warfarin in terms of the overall frequency of strokes, blood clots, heart attacks, hemorrhages and other problems in patients with atrial fibrillation.
Connolly and Uchino believe that, despite the risks, it seems more beneficial to take dabigatran. Many doctors are more likely to prescribe this drug because warfarin can cause serious bleeding, so patients taking it require constant monitoring. – We must remember that every drug has side effects, so you should always take into account both its benefits and its harmfulness – adds Uchino.
Text: Shari Roan