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(Reuters Health) - Despite new treatment options in recent years, almost four in 10 people with an irregular heartbeat that increases their risk of stroke still don’t get anti-clotting medications that make strokes less likely, a U.S. study suggests.
For the study, researchers examined medication data collected from 2008 to 2014 for 655,000 patients with atrial fibrillation, an irregular rapid heartbeat that can lead to blood clots, heart failure and chronic fatigue. Most strokes occur when a clot blocks an artery carrying blood to the brain.
At the start of the study, treatment options included older anticoagulants, also known as blood thinners, such as warfarin (Coumadin) that lengthen the time it takes for clots to form in the blood. These drugs also carry an increased risk of bleeding that requires careful monitoring with blood tests.
By the end of the study, new blood thinners known as direct oral anticoagulants came on the market that don’t require periodic blood tests, including dabigatran (Pradaxa), rivaroxaban (Xarelto) and apixaban (Eliquis).
With the debut of these new treatment options, the proportion of atrial fibrillation patients eligible to take blood thinners who got prescriptions for these drugs climbed from 52 percent to 61 percent during the study period.
"Our study demonstrated the rate of prescription of oral anticoagulation for atrial fibrillation increased with the availability of direct oral anticoagulants," said lead study author Dr. Lucas Marzec of the University of Colorado School of Medicine in Aurora and the Colorado Cardiovascular Outcomes Research Consortium.
"However, despite this increase, more than one third of the patients at risk for stroke are not on oral anticoagulation," Marzec said by email. "Further, patients at highest risk of stroke are least likely to be prescribed oral anticoagulation."
In atrial fibrillation, electrical impulses in the upper chambers of the heart are chaotic, causing that part of the heart muscle to quiver rather than contracting normally. As a result, blood doesn’t move as well to the heart’s lower chambers, which can lead to the formation of clots.
People with atrial fibrillation have a much higher risk of stroke risk than those without the disorder. Not every person with atrial fibrillation can take blood thinners, but people with risk factors like advanced age, diabetes, congestive heart failure or a history of stroke should consider taking these medicines, Marzec said.
For the study, Marzec and colleagues analyzed data from a national registry of cardiology patients. They excluded patients who had a documented reason in their medical records that would make them ineligible to take blood thinners.
Over the study period, use of warfarin declined from 52 percent to 35 percent of patients, researchers report in Journal of the American College of Cardiology.
The newer medicines weren't available at the start of the study, but by the end 26 percent of patients were getting these treatments.
Because the decrease in older medicines was more than offset by use of newer alternatives, the researchers conclude that the new generation of drugs is helping to get more patients to take needed blood thinners.
One limitation of the study is that not every cardiology practice participates in the registry, and it's possible certain characteristics of the practices in the registry might have influenced the prescription patterns found in the study, the authors note.
Using the registry records may have also overestimated how many patients get anticoagulants, Dr. Eric Peterson of Duke University Medical School in Durham, North Carolina, writes in an accompanying editorial. It also didn't offer insight into whether costs or insurance benefits might have driven prescription choices for some patients because the newer medicines may be more expensive, Peterson writes.
"The majority of patients with atrial fibrillation should be on blood thinners," Peterson said by email.
"Some may not require them because of low risk for strokes, while others may not be able to take them because of risk of bleeding," Peterson added. "While other treatments can be considered, all patients with atrial fibrillation should talk to their doctors about consideration for a blood thinner."