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“One
minute, we had patients calling us to complain they
were not getting drug-eluting stents. The next minute,
they were calling to complain because they were
getting them,” said Munich-based cardiologist
Sigmund Silber, one of the speakers at this year’s
Transcatheter Cardiovascular Therapeutics (TCT)
meeting.
Silber
had been assigned the “con” side in a genial but
important debate over whether doctors should hold back
on using drug-eluting stents—or DESs—while
questions about their safety are resolved. DESs are
thin, drug-coated, mesh tubes used to open up
dangerously blocked arteries. Doctors use them because
they are are less likely to cause restenosis—the
major complication of traditional “bare-metal”
stents.
The
story demonstrates the massive challenge of bringing
new treatments to today’s market.
The
problem with DESs came to wide public attention this
fall, when headlines streamed from the World Congress
of Cardiology in Barcelona, warning that compared to
bare metal stents, these devices seem to cause higher
rates of late stent thrombosis (blood clots), leading
to a slightly higher rate of myocardial infarction and
death.
Obviously,
these are effects to be avoided, and the FDA promptly
jumped on the matter, not banning the devices, but
saying it was monitoring the issue and would convene a
panel on it before the end of the year. Specialists
like Silber started getting those frantic patient
calls, and many were left scratching their heads.
“What to do?”
Should they react to the news by abandoning
DESs or, as Silber argued in the TCT debate, trust
that the stents are doing more good than harm?
Silber
pointed out that there is only a very small increase
in risk, and at least part of that could be due to
problems with the data. In addition, there is a
growing feeling that, at least in the US, some doctors
may not be prescribing DES patients long enough
courses of clopidogrel (Plavix)—an antiplatelet that
helps prevent stent thrombosis. “In the spirit of
debate,” Silber said that some studies cited to
prove that DESs are dangerous could be described as
“unethical” if you believe that longer term
antiplatelet therapy is the most appropriate standard
of care.
Silber’s
opponent in the debate was David P. Faxon of
Boston’s Brigham and Women’s Hospital. He agreed
there are problems with US antiplatelet prescribing
guidelines because they “were based on the protocol
used to get FDA approval.” Many doctors know that,
and FDA is re-examining the prescribing guidelines.
What
does it all mean? Silber and Faxon agreed the stent
thrombosis effect is probably real (new data presented
at TCT supports that), but the trend is relatively
small, and “It would take a 20,000-patient study,”
Silber said, to answer whether the benefits of these
devices outweigh the risks. Meanwhile, many doctors
feel comfortable prescribing DESs as long as the
patients are well selected and given appropriate
medication on top.
Technology
holds out hope: It should be possible to engineer new
stents without this alarming potential side effect.
Until then, doctors must grapple with the age-old
tension: Should they give patients something new,
bold, and seemingly better? Or are they turning their
patients into unwitting guinea pigs by doing so?
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