* Study urges doctors to be aware of risks
* Researchers say more study needed to explain why
By Julie Steenhuysen
CHICAGO, Aug 30 Blacks treated with a
drug-coated stent to open clogged heart arteries are nearly
three times more likely to develop a life-threatening blood
clot than whites, U.S. researchers said on Monday.
They said being black was the strongest predictor of stent
thrombosis -- blood clots that can occur after a stent is
implanted -- even after considering other known risk factors
such as diabetes, high blood pressure or kidney problems.
"Physicians and patients need to know that
African-Americans are at a higher risk of developing stent
thrombosis, which is associated with heart attack or death,"
said Dr. Ron Waksman of Washington Hospital Center and
professor at Georgetown University, whose study appears in the
Stents, made by companies such as Boston Scientific
(BSX.N), Abbott Laboratories (ABT.N), Medtronic Inc (MDT.N) and
Johnson & Johnson (JNJ.N), are wire-mesh coils used to prop
open arteries narrowed by fatty deposits called plaque.
Many models release drugs over time that help prevent scar
tissue from building up and blocking the artery.
Sanofi-Aventis' (SASY.PA) anti-clotting drug clopidogrel or
Plavix is typically prescribed after a stent is implanted to
keep patients from developing blood clots, but some patients,
including some blacks, get them anyway.
Waksman and colleagues examined rates of stent thrombosis
in nearly 1,600 blacks and 5,600 nonblacks given a drug-eluting
stent. They checked for factors such as socioeconomic status or
other health conditions that could explain higher rates of
After adjusting for different rates of diabetes, high blood
pressure, kidney problems and how faithfully patients took
their anti-clotting medication, they found being black was the
biggest predictor of whether a patient would have a blood clot
after getting a stent.
Blacks were nearly three times as likely to experience
clotting as nonblack patients, with 1.71 percent of black
patients having a clot after 30 days, compared with 0.59
percent of nonblacks.
The rate jumped to 3.67 percent for blacks after three
years, compared with 1.25 percent of nonblacks.
And nearly a quarter of black patients who had been in the
study were dead three years later -- for any reason -- compared
with 13 percent of the nonblack patients.
Because blacks in the study were actually more likely than
whites to take Plavix, and socioeconomic status was not a major
predictor of blood clots, the researchers said being black is
likely an independent predictor of who will develop a blood
clot after getting a stent.
"Because our analysis adjusts for traditional variables
associated with racial disparities in health care, further
mechanisms such as genetic polymorphisms and responsiveness to
antiplatelet therapy must be pursued," Waksman and colleagues
Some people are not able to convert Plavix to its active
form, and the researchers said blacks may be more prone to this
(Editing by Jerry Norton)