Most people at risk of stroke deprived of anti-clotting drugs

Most strokes occur when a clot blocks an artery carrying blood to the brain, known as an ischemic stroke.

More than four in five stroke patients with a history of heart rhythm problems didn’t get any blood thinners, or didn’t take enough to help prevent a stroke before they had one, a U.S. study suggests.

Most strokes occur when a clot blocks an artery carrying blood to the brain, known as an ischemic stroke. The study focused on more than 94,000 stroke patients with atrial fibrillation, an irregular rapid heartbeat that can lead to stroke, heart failure and chronic fatigue.

Before their stroke, just 16 percent of these atrial fibrillation patients were taking adequate doses of older anticoagulants, which are also known as blood thinners, such as heparin or warfarin (Coumadin) that lengthen the time it takes for clots to form in the blood or of newer anticoagulants like dabigatran (Pradaxa), rivaroxaban (Xarelto) or apixaban (Eliquis).

“Atrial fibrillation patients not taking anticoagulants or taking inadequate anticoagulants are at high risk for stroke,” said lead study author Dr. Ying Xian, a neurology researcher at Duke University Medical Center in Durham, North Carolina.

“Even in rare cases where therapeutic anticoagulation failed to prevent a stroke, patients who were taking (newer anticoagulants) or warfarin were 35 to 44 percent less likely to experience severe stroke, 21 to 25 percent less likely to die, and 40 to 50 percent more likely to function independently after a stroke,” Xian added by email.

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. This can lead to the formation of clots that can then travel through the arteries. Atrial fibrillation patients have up to seven times the stroke risk of people without the disorder.

Atrial fibrillation makes stroke up to five times more likely, and accounts for up to 15 percent of all ischemic strokes.

To see how often atrial fibrillation patients received blood thinners to avert clots, Xian and colleagues examined data on patients hospitalized for stroke from 2012 to 2015 in one of 1,622 hospitals participating in the American Heart Association and American Stroke Association’s “Get With the Guidelines–Stroke” program.

Patients were about 80 years old on average and more than half were women. Roughly 40 percent of patients got antiplatelet therapy like aspirin instead of anticoagulants before their strokes and 30 percent were taking no anticlotting therapy, researchers report in JAMA.

The possibility of side effects may partly explain the limited use of blood thinners. Long-term use of the older blood thinner warfarin, for example, can increase the risk of severe bleeding, and it’s inconvenient because it requires frequent lab tests and check-ups to ensure that patients have the right dose.

Newer anticoagulants are associated with fewer serious bleeding complications than warfarin but can have serious complications like severe heartburn, nausea or vomiting.

One limitation of the study is that it lacked a control group of atrial fibrillation patients who didn’t have a stroke, the authors note. It also wasn’t an experiment designed to prove that certain therapies can directly prevent stroke.

Still, the findings suggest that as many as 88,000 strokes might be prevented each year if people with atrial fibrillation took recommended doses of anticoagulants, Xian said.

“While some of the patients in this registry study may have had legitimate reasons to avoid antithrombotic therapy, this extremely low application rate of effective treatment to prevent stroke is disconcerting,” said Dr. Samuel Wann, a cardiologist at Ascension Health in Milwaukee, Wisconsin.

“A lot of work is still needed in order to get with the guidelines,” Wann, who wasn’t involved in the study, said by email.

Lack of awareness is part of the problem, said Dr. Jonathan Hsu, a heart specialist at the University of California, San Diego, who wasn’t involved in the study.

“Although an oral anticoagulant is a feared medication to be prescribed because of the risk of bleeding, many studies have shown that the improvement in stroke risk reduction far outweighs the bleeding risk in the grand majority of atrial fibrillation patients,” Hsu said by email.

( Source : reuters )
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