New Study Raises Concerns That Drug-Coated Heart
Stents May Lead to Potentially Fatal Clots
09-03-2006 8:08 PM
By MARIA CHENG

BARCELONA, Spain --  Experts expressed concerns
Sunday that drug-coated heart stents _
metal-mesh tubes used to prop open coronary
arteries _ may in rare instances lead to
potentially fatal blood clots.
Studies released Sunday at the World Cardiology
Congress in Barcelona raised new concerns about
the risks that may accompany the drug-coated
stents, which were introduced in 2000 as an
improvement on bare-metal stents.
Nearly 6 million people worldwide now have the
drug-lined versions. The devices are intended to
keep arteries open after having been cleared of
fatty deposits and are often credited with
saving patients from future heart attacks or
bypass surgery.
A Swiss-Dutch study tracked 8,146 patients and
found that recipients of drug-coated stents were
at increased risk of thrombosis, or blood clots,
that can occasionally result in death.
Two other Swiss studies, analyses of presented
and published information discussed at the
cardiology conference, also found that
first-generation drug-coated stents had higher
links to thrombosis compared to bare metal
stents.
In bare metal stents, heart cells naturally grow
to cover the stent, providing a natural
biological lining. But in the drug-coated
versions, the drugs prevent tissue growth _
which is both their intent and their possible
downfall.
Drug-coated stents were previously viewed as a
great advance since the drugs they emitted
prevented cells that could block the arteries
from growing. A thick growth of cells is
undesirable, but a thin layer of cells lining
the artery is essential. In some instances,
drug-coated stents have prevented this minimal
protective cell layer from growing, leaving
exposed metal, which essentially can act as a
clot magnet.
"This is potentially explosive information,"
said Dr. Steven Nissen, president of the
American College of Cardiology and director of
cardiology at the Cleveland Clinic.
"It certainly makes me pause with substantial
concern," said Nissen. He said there is already
a shift in the U.S. away from using drug-coated
stents in favor of their uncoated predecessors.
Doubts about drug-coated stents were initially
raised in March by a small-scale Swiss study,
though there have long been naysayers about
their potential adverse effects. Results from
the Swiss-Dutch study found that the incidence
of thrombosis does not diminish as time passes.
Researchers found that the possibility of
thrombosis continued to pose a risk, though
minimal, during the first three years following
stent implantation. Other issues, however, such
as patient compliance with taking prescribed
medications, may play a role in blood clot
formation.
Some medical experts worry that the financial
implications of reducing usage of the profitable
drug-coated stents may be taking priority over
improving patients' health.
"It's time to stop and re-evaluate," said Dr.
Salim Yusef, professor of medicine and director
of cardiology at McMaster University, Hamilton,
Canada.
"Having done six million of these procedures,
isn't it a terrible indictment on us that we
don't have long-term safety data on these?" he
said.
The drug-coated stent market last year was
estimated as being worth more than $5 billion,
and is dominated by Boston Scientific and
Johnson & Johnson. Drug-coated stents are also
far more profitable, selling for about $2300
each compared to the cheaper $700 bare metal
versions.
While significant, these new findings are not
expected to radically alter the use of
drug-coated stents in the immediate future.
"This won't change clinical practice right now,
but it shows us that this a problem that needs
to be investigated with larger trials," said Dr.
Raymond Gibbons, president of the American Heart
Foundation.
Nissen, however, was more skeptical.
"There is a tendency for physicians to switch
practices even before data is solid," he
explained. "If there's a suspicion, why take the
risk?"

... I know it all. I just can't remember it simultaneously.