MONDAY, Nov. 5 (HealthDay News) -- About a quarter of people who
experience the dangerous blood clots in the legs or lungs known as
venous thromboembolisms (VTEs) develop them for no discernable
reason, and most will receive a powerful anti-clotting drug such as
warfarin in the months after the clot forms.
But what about longer-term care, to ward off a recurrent clot,
or events such as heart attack or stroke? A new study suggests that
patients who go on low-dose daily aspirin after they are weaned off
more powerful anticoagulants can derive real benefit.
While this study alone could not show a significant effect for
aspirin therapy in preventing a recurrent clot for these patients,
it did show a significant lowering of overall cardiovascular risk
for such complications as heart attack, stroke, major bleeding or
death from any cause.
The study was presented Sunday at the American Heart
Association's annual meeting in Los Angeles, and was published
simultaneously in the
New England Journal of Medicine.
The study authors said they saw a "non-significant" trend
hinting at aspirin's ability to prevent a second VTE, but the study
group was simply too small to push that to statistical
However, they added, when the findings from this study were
combined with those of a similar trial called WARFASA, the combined
didshow that daily aspirin could prevent recurrent blood
"The essential message of the study that we are presenting today, and combining that with the WARFASA study that was published earlier this year in the NEJM, is that aspirin does have a benefit: about a 30 percent risk reduction of recurrent vein thrombosis, and also about a similar effect in reducing other major vascular events stroke, myocardial infarction [heart attack] and cardiovascular death," said study author Timothy Brighton, a consultant hematologist in Sydney, Australia.
VTEs include sudden, potentially life-threatening clots in the
legs (known as deep vein thrombosis, or DVT) and clots that travel
to the lungs, called pulmonary embolisms.
As Brighton explained, in about 75 percent of cases, these clots
have a known cause injury, surgery or underlying illness, for
example. But for the other quarter of patients, the cause is
More than 800 people with a VTE of uncertain cause were included
in the new study. Approximately half were given low-dose (100
milligrams/day) daily aspirin, while the other half received a
placebo, after they had completed their initial regimen of a more
powerful anticoagulant. The patients were then followed for an
average of more than three years.
Brighton noted that patients often cannot continue on
anticoagulants such as warfarin indefinitely, because of bleeding
risks and inconveniences associated with these drugs.
"The question comes, though, after [discontinuation of initial anti-coagulation therapy], what do you do?" he said.
The answer, from the new study as well as WARFASA, seems to be
low-dose daily aspirin. Brighton's group also pointed out that
incidents of bleeding were similar for those on low-dose aspirin
and placebo, suggesting that aspirin does not raise bleeding
One cardiologist said the study is encouraging for patients. Dr.
Stephen Green, associate chairman of the department of cardiology
at North Shore University Hospital in Manhasset, N.Y., said that
while it's true the trial (on its own) did not find a significant
effect of aspirin in reducing VTE recurrence, "the study was
positive enough that physicians should consider adding aspirin when
stopping warfarin in patients who are reasonable candidates for
But he also noted that since the time of the trial, many
patients with VTE have now moved from initial warfarin therapy to
treatment with newer blood-thinning agents such as Xarelto and
More study might be needed to assess aspirin's effectiveness in
that clinical scenario, he said.
Find out more about deep vein thrombosis at the
U.S. National Library of Medicine.
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