May 11, 2012
Dear Mayo Clinic:
What are the new anti-coagulating drugs the FDA is approving for atrial fibrillation? Which would you recommend?
Three new anticoagulant drugs can help prevent blood clots in people with atrial fibrillation. Two have been approved by the Food and Drug Administration (FDA), and one is still under review. These drugs appear to have a variety of benefits over warfarin, the standard anticoagulant therapy used for atrial fibrillation. But there are some drawbacks, too, including a significant cost increase.
Atrial fibrillation is an irregular heart rate that often results in poor blood flow to the body. During atrial fibrillation, the heart's two upper chambers, called atria, beat irregularly and out of sync with the two lower chambers, or ventricles. This abnormal heart rhythm may cause blood to pool in the atria and form clots. A blood clot that forms could be carried in the circulation from your heart to your brain. There, it may block blood flow, causing a stroke.
Anticoagulant medications, sometimes called blood thinners, can greatly lower the risk of stroke in people who have atrial fibrillation. For years, the standard anticoagulant used for atrial fibrillation has been warfarin. Although very effective at preventing blood clots, warfarin is a powerful medication that can have serious side effects, including bleeding within the brain and elsewhere in the body.
The new anticoagulant drugs include dabigatran, approved by the FDA in 2010, and rivaroxaban, approved in 2011. The FDA is currently reviewing a third, called apixaban. In studies, these drugs appear to be safer than warfarin in terms of bleeding within the brain. Research has also shown them to be either as effective or more effective than warfarin at preventing strokes, although the specific findings vary among those studies.
One advantage to these new drugs is that they are more convenient for patients because they do not require the close monitoring that warfarin does. Warfarin can interact with many other medications, as well as certain foods. As a result, regular blood tests are required to ensure that a person taking warfarin is receiving the correct dose. The warfarin dose may need to be adjusted, depending on blood test results. The new anticoagulant drugs have a fixed dose that does not require ongoing monitoring or individual dosing adjustments.
A disadvantage to the new drugs, particularly dabigatran, is that they may increase the risk of bleeding complications in people older than 75, as well as those with kidney problems. In addition, if bleeding starts in someone taking these drugs, currently there is no antidote available to quickly stop the bleeding, as there is with warfarin. In addition, these drugs are significantly more expensive than warfarin. And one of them, dabigatran, needs to be taken twice a day — rather than once a day with warfarin — so patients have to be willing to comply with a more frequent medication schedule.
Although one of these drugs cannot be recommended over the others for everyone, certain people are good candidates to try a new anticoagulant. They include those younger than 75 without other health concerns who have not previously taken warfarin, as well as people who have taken warfarin but have had required frequent dose adjustments.
If you already take warfarin for atrial fibrillation, your dose is stable and you have easy access to blood monitoring, then there may be no need to change. These new drugs generally are not appropriate for most people older than 75, those with additional health problems that increase the risk of bleeding, and people who have kidney disorders.
If you have atrial fibrillation and you think you may be a good candidate for a new anticoagulant medication, talk to your doctor to see if one might be right for you.
— Bernard Gersh, M.B., Ch.B., D.Phil., Cardiovascular Diseases, Mayo Clinic, Rochester, Minn.