Researchers at American Heart Association have found a new blood thinner that can be used instead of warfarin (Coumadin) to treat the complicated heart rhythm disorder, medically called arterial fibrillation. The drug was approved by the FDA last month.

Rivaroxaban (Xarelto) is proven to be as effective as warfarin, and perhaps more advanced, also reducing the risk of serious bleeding events which happen commonly when warfarin is used.

"In October of 2006, the FDA [U.S. Food and Drug Administration] issued a black-box warning for warfarin due to a growing appreciation of its hazards in routine clinical practice," said Dr. Elaine Hylek, associate professor, BUSM. "The requirement for monitoring has relegated millions of people to no therapy or ineffective therapy because of lack of access to monitoring and an intense search for an alternative with more predictable dose responses."

Researchers studied the effectiveness of the new drug, as warfarin has been used for ages. The trial involved researchers from over 45 countries, 1,215 medical centers and 14,269 patients with arterial fibrillation, who were likely to get a stroke very soon.

Participants, median age 73, were randomly assigned to receive rivaroxaban or warfarin.

Researchers analyzed only those who took the drug on a continuous basis, and found that the drug showed a 21 percent fall in this risk rate for stroke and non-CNS systemic embolism -- a type of blood clot.

"In a [real-world] environment where patients are going to come on and off drugs, rivaroxaban didn't meet statistical significance for superiority [against warfarin]," said Hylek. "I think it would be a more iron-clad situation [in terms of demonstrating superiority] if the intention-to-treat analysis demonstrated superiority."

Hylek added that she was not "embracing the superiority of rivaroxaban, but it's important that the new kid on the block is saying, 'I'm not inferior to you,' given that so many people can't take warfarin because of monitoring problems."

However, there were fewer incidences of death due to a heart attack after rivaroxaban.