Blood thinning drugs may raise stroke risk for some a-fib patients

New research suggests, but cannot prove, that blood thinning drugs may raise stroke risk for seniors with atrial fibrillation who also have kidney disease
By HealthDay News  |  Feb. 16, 2018 at 10:21 AM
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FRIDAY, Feb. 16, 2018 -- Taking blood-thinning drugs is typically thought to ward off stroke in people with the heart rhythm disorder atrial fibrillation.

However, new research out of Britain hints -- but cannot prove -- that the drugs might actually raise the odds of stroke in seniors with a-fib who also have kidney disease.

"Chronic kidney disease is common among older people, and one in three people affected also have atrial fibrillation, commonly called an irregular heartbeat -- and for that, they typically get prescribed blood thinners to reduce their risk of stroke," noted lead researcher Shankar Kumar, of University College London.

However, "we found that in this particular group, their medication seems to do the opposite of its intended effect," Kumar, a researcher with UCL's Centre for Medical Imaging, said in a university news release.

Still, one U.S. cardiologist said that patients who fall into this category don't need to panic.

Dr. Michael Goyman directs clinical cardiology at Northwell Health's Long Island Jewish Forest Hills hospital, in Forest Hills, N.Y. He stressed that the new study couldn't prove cause-and-effect, and contained numerous limitations.

So, while the findings do need to be followed up in a more rigorous trial, "patients should not make decisions about the benefit of blood thinners without consulting their physicians," Goyman said.

The new study included more than 4,800 British people, aged 65 and older, who had chronic kidney disease plus a recent diagnosis of a-fib.

Half of the patients were taking some sort of blood thinner for the heart condition.

Over an average follow-up of nearly 17 months, those taking blood thinners were 2.6 times more likely to have a stroke and 2.4 times more likely to have bleeding than those who did not take the drugs.

However, the death rate in the blood thinner group was slightly lower, and might have been due to a reduced risk of fatal stroke or heart attack, according to the study.

The findings were published Feb. 14 in the BMJ journal.

According to Kumar's group, the new findings suggest doctors need to be more careful about prescribing blood thinners to seniors with chronic kidney disease, at least until more research provides a clearer idea of the risks.

"People with chronic kidney disease tend to have numerous severe complications, including cardiovascular illnesses," explained senior study author John Camm, a professor of clinical cardiology at St George's, University of London.

"As their blood clots more but they also bleed more easily, it is extremely difficult to strike a balance between different treatments," he said.

Kumar added: "This is clearly a very complex area. We strongly call for randomized, controlled studies to test the clinical value and safety of anticoagulant drug therapy for people with both atrial fibrillation and chronic kidney disease."

Dr. Satjit Bhusri is a cardiologist at Lenox Hill Hospital in New York City. He wasn't involved in the new research, but reviewed the findings and agreed that -- for now at least -- patients shouldn't be concerned.

"This observational study is just that, observational," and as such can't prove that the blood thinners are somehow causing more strokes, Bhusri said. He added that important details -- the types of blood thinners used, for example -- weren't included in the study.

In the end, Bhusri agreed with Kumar and Giyfman that more research is needed.

In the meantime, he said, "the choice of blood thinner should be a patient-specific preference and risk-versus-benefit should be an active discussion. I would not rely on this study as a source of reference in that discussion."

More information

The U.S. Agency for Healthcare Research and Quality has more on blood thinners.

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