Study Pits New Blood Thinner Against Warfarin For Irregular Heartbeat

Both drugs appeared equally effective, but newer rivaroxaban may be be easier for some to use

HealthDay SHARE

By Denise Mann
HealthDay Reporter

WEDNESDAY, Aug. 10 (HealthDay News) -- A new drug that lowers stroke risk among people with an irregular heartbeat may give the old standby, warfarin, some competition, a new study shows.

Individuals with an erratic heartbeat known as atrial fibrillation are at increased risk for ischemic stroke, which is caused by a blockage such as a blood clot. For this reason, they have to take blood-thinning medications to lower this risk. Warfarin (also known as Coumadin) is considered the gold standard medication, but it often requires monitoring, adjustments and stringent dietary restrictions.

The new trial pitted the newer drug, rivaroxaban (Xarelto), against warfarin in more than 14,000 patients who were randomly assigned either warfarin or rivaroxaban. Neither the patients nor the doctors knew who was taking which drug.

The new agent proved to be as effective as warfarin at reducing the risk of ischemic stroke -- the most common kind of stroke -- but it did not need to be monitored as closely as warfarin since it is given as a one-size-fits-all dose.

Although potentially lifesaving, all blood-thinning drugs confer a risk of potentially life-threatening bleeding. The two medications had similar bleeding rates overall, but the new agent was less likely to cause fatal bleeds or bleeding in the brain, according to the study, which appears in the Aug. 11 issue of the New England Journal of Medicine .

In contrast, bleeding in the gastrointestinal region occurred more often in the rivaroxaban group, as did bleeds requiring transfusion.

The study was funded by Johnson & Johnson Pharmaceutical Research & Development and Bayer Healthcare, the makers of rivaroxaban.

The new drug is already approved to treat deep vein thrombosis, or blood clots that form deep in a vein somewhere in the body, usually the leg. Rivaroxaban is not the only new blood thinning drug in the pipeline, however: Pradaxa (dabigatran etexilate) recently got the FDA's nod for lowering stroke risk among people with atrial fibrillation, and Eliquis (apixaban) is also making its way down the drug development pike.

Study author Dr. Manesh R. Patel, an assistant professor of medicine at Duke University School of Medicine in Durham, NC, said that the new agent may be "a reasonable alternative to warfarin, with less intracranial or fatal bleeding." Many people on warfarin need to have their blood monitored to ensure that a blood clotting test known as the International Normalized Ratio (INR) is where it should be, and there are also many dietary restrictions, he noted.

"You can't eat broccoli and other vitamin-K rich foods" on warfarin, Patel said. In contrast, the new drug is taken once daily and has a more consistent effect. "It is a useful alternative with fewer drug-drug and drug-food interactions and may be significantly easier to take," Patel said. If and when the drug is approved to treat atrial fibrillation, doctors will have to develop an appropriate way to transition patients from warfarin to the new drug, he said.

Dr. Gregory J. del Zoppo, a professor of medicine at the University of WashingtonHarborview Medical Center in Seattle, wrote an accompanying journal editorial. He said that the multiple analyses in the new study had "muddied the waters" regarding rivaroxaban's efficacy. "Some people do well with warfarin and don't complain about one blood draw a month and watch what they eat," he said. "For those folks, warfarin is still the standard."

On the other hand, the new agent may be an option for people who are more difficult to manage on warfarin, he added. "There are a number of people who are difficult to control and for whom the monitoring is complicated and intrusive, and they have to go monthly or weekly to have blood drawn," he said.

Dr. Kousik Krishnan, associate professor of medicine at Rush University Medical Center in Chicago, said that the new drug and others like it "will be game-changing for all of us that treat atrial fibrillation."