A class of popular new clot-busting drugs is behind a dramatic rise in people being treated for heart-rhythm problems, a new study suggests.

The findings, published in the American Journal of Medicine, show the growing number of patients treated for atrial fibrillation is largely driven by the popularity of new direct oral anticoagulants (DOAC) — blood thinners that have been heavily advertised as simple to use.

Their use has tripled from 2013-2014, according to the new study by the University of Michigan Frankel Cardiovascular Center.

Across the United States doctors treated more than 2.83 million patients in the last quarter of 2014 — up from 2.05 million at the start of 2009 — for use of anticoagulants. By comparison, warfarin therapy visits declined between 2009 and 2014.

Last year, 57 percent of anticoagulant visits were related to warfarin use compared to 43 percent related to DOACs, according to the study.

"The data provides a promising outlook about atrial fibrillation which is known for being undertreated," says lead researcher Geoffrey Barnes, M.D., a cardiologist at the University of Michigan Health System and researcher at the Institute for Healthcare Policy and Innovation.

"When we don't treat atrial fibrillation, patients are at risk for stroke. By seeking treatment, patients set themselves up for better outcomes."

Dabigatran accounted for the majority of prescriptions for DOACs from 2010-2012, but as other drugs have come on the market, rivaroxaban (Xarelto) has become the most commonly prescribed oral anticoagulant during atrial fibrillation office visits, the study showed.