Comparing the New Blood Thinners to Warfarin

May 31, 2013 -- More than 2 million Americans have an abnormal heart rhythm known as atrial fibrillation, raising their risk of blood clots leading to stroke. For many years, the blood thinner Coumadin (warfarin) was the only game in town to help lower that stroke risk.

In the past 3 years, though, three new blood thinners, also called anticoagulants, have been FDA-approved for atrial fibrillation.

WebMD asked two doctors to  compare them to warfarin and describe the risks and benefits of each. Neither doctor has ties to the drug companies making the blood thinners.

All three new drugs are approved for atrial fibrillation treatment in people who do not have heart valve problems or artificial valves.  One of the three also has FDA approval for additional conditions.

Atrial fibrillation disrupts the flow of blood through the heart. As blood pools, it's more likely to form clots that can travel to the brain, causing a stroke.

The new drugs are different in some respects but work in the same general way. ''All of them work on the clotting 'cascade,'" says John Doherty, MD. He is a professor of medicine at the Thomas Jefferson University School of Medicine, Philadelphia, and a member of the American College of Cardiology's Anticoagulation Initiative.

That cascade ''is a series of events by which different compounds are generated and ultimately result in blood coagulation [clotting]."

The three new drugs, which target various points along that cascade, include:

Pradaxa (dabigatran).It was approved by the FDA in October 2010 for prevention of stroke and blood clots in people with atrial fibrillation.

Xarelto (rivaroxaban). It was approved in November 2011, to treat atrial fibrillation. It had been approved earlier to lower the risk of blood clots after hip and knee replacements.

In November 2012, the FDA also approved it to treat deep vein thrombosis, (blood clots that occur usually in the lower leg and thigh) and pulmonary embolism (the condition that results when a blood clot from a vein breaks off and travels to an artery in the lungs and blocks blood flow.)

Eliquis (apixaban). It was approved in December 2012 to lower the risk of stroke and dangerous blood clots in patients with atrial fibrillation.

"We are excited there are these new options, but each patient will have to have a conversation with their physician and decide what is appropriate for them," says Clyde Yancy, MD. Yancy is chief of cardiology at Feinberg School of Medicine, Northwestern University, and past president of the American Heart Association.

While the new drugs offer some benefits over warfarin, some patients may do better to stay on the old drug if they are doing well, says Doherty.

Yancy agrees. "If you are doing well on warfarin, there is no reason to take a more expensive drug unless the other advantages are so uniquely important it's worth the transition," he says.

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