More than a third of patients with a heart
rhythm problem that can cause a stroke are incorrectly given aspirin instead of
the blood-thinning medications they need to make this complication less likely,
a U.S. study suggests.
Most
strokes occur when an artery that carries blood to the brain gets blocked by a
clot. While aspirin can prevent clots, it doesn’t work well as blood thinners
to prevent stroke in these patients, guidelines say.
Researchers
analyzed data on more than 500,000 people with atrial fibrillation, an
irregular rapid heartbeat that can lead to stroke, heart failure and chronic
fatigue.
Roughly
40 percent of these patients got aspirin instead of prescriptions for blood
thinners – also called anticoagulants.
“By
prescribing aspirin, we may be fooling ourselves that the patient may be
protected from stroke when this is not the case – blood thinners have been
shown to be clearly more effective than aspirin in preventing stroke for atrial
fibrillation patients,” lead study author Dr. Jonathan Hsu, a heart specialist
at the University of California, San Diego, said by email.
In
atrial fibrillation, electrical impulses in the upper chambers of the heart are
chaotic, and the atrial walls 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 travel through the arteries. Atrial
fibrillation patients have up to seven times the stroke risk of people without
the disorder.
To see
how many atrial fibrillation patients receive blood thinners to avert clots,
Hsu and colleagues reviewed medical and prescription data collected from 2008
to 2012 in a national registry of people with cardiovascular disease.
One group of about 210,000 people in the study
were at least 75 years old and had other risk factors for stroke such as
congestive heart failure, diabetes, or high blood pressure. Roughly 38 percent
of these patients were treated with aspirin and nearly 62 percent were
prescribed anticoagulants.
A
second group of roughly 295,000 people were between 65 and 74 years old. Among
this subset of atrial fibrillation patients, 40 percent were treated with
aspirin and 60 percent got anticoagulants.
For
both groups, patients prescribed aspirin were younger, slightly less
overweight, and more likely to be female or have other medical problems such as
diabetes, hypertension, high cholesterol, coronary artery disease, a prior
heart attack or peripheral artery disease, researchers report in the Journal of
the American College of Cardiology.
The
possibility of side effects may partly explain the limited use of blood
thinners.
Long-term
use of the older blood thinner warfarin (Coumadin), 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
anticoaulants are associated with fewer serious bleeding complications than
warfarin, Dr. Samuel Wann, a cardiologist at Ascension Health in Milwaukee,
Wisconsin, notes in an accompanying editorial.
One
limitation of the study is that researchers lacked data on whether patients had
medical reasons that would prevent their use of blood thinners, the authors
note.
People
with conditions that can increase the risk of bleeding problems – like high
blood pressure, cancer, kidney problems or alcoholism – might not be able to
take warfarin.
Another
shortcoming is that they assessed blood thinner prescriptions at initial doctor
visits, and didn’t see whether people stopped or started medication based on
follow-up exams, the researchers also point out.
Wann
told Reuters Health there are a wide variety of reasons why doctors might
prescribe aspirin when blood thinners are the recommended treatment.
"Lack
of knowledge, patient compliance and cost may all explain failure to prescribe
effective treatment," Wann said by email.
In
some cases, Wann added, doctors may be "taking the easier way out because
the adverse consequences of not prescribing anticoagulation are not immediately
apparent."
SOURCE: bit.ly/28KpSMH Journal of the American College of
Cardiology, online June 20, 2016.
Representative
Image
Source:
Reuters
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