New
long-term research now suggests that fully biodegradable stents are safe to use
in heart arteries.
Reporting
in the April 16 issue of Circulation, Japanese researchers said
a 10-year study has shown the biodegradable Igaki-Tamai stent, made of a
cornstarch-based material, dissolves into the artery wall, leaving no
permanent foreign material in an artery and reducing the occurrence of an
in-stent blood clot.
According
to the study, survival
rates from all causes was 87 percent and rates of major heart-related
complications were similar to those seen with metal stents.
Stents,
the tiny mesh tubes inserted into heart arteries to keep open and allow blood
to flow to the heart, are far from fail-safe. New blockages can -- and
do -- occur.
So
scientists have been trying to develop new stents, including ones coated with
blood-thinning medications. Metal stents, sometimes coated with drugs, remain
in the body where they can reclog.
The
Igaki-Tamai stent, developed by Kyoto Medical Planning Co., is used in nine
European Union countries and Turkey to treat peripheral
artery disease, or blocked arteries in the legs. It is not used to treat
blocked heart
arteries in any country.
Study
author Dr. Kunihiko Kosuga, director of cardiology at Shiga Medical Center for
Adults in Moriyama City, predicted in a journal news release that "fully
biodegradable stents may hold an important position as the next generation of
coronary devices."
In the
study, 50 people received 84 Igaki-Tamai stents between September 1998 and
April 2000. Researchers report that the survival rate from heart-related death
was 98 percent. Half of the individuals experienced major heart-related
complications, which is in line with studies of metal stents. The stent was
totally absorbed in three years.
"There
is a risk of heart attack if a stent does not get incorporated into the blood
vessel wall," explained Dr. Barry Kaplan, vice chairman of cardiology at
North Shore University Hospital in Manhasset, N.Y., and Long Island Jewish
Medical Center in New Hyde Park, N.Y. Once the metal stent is absorbed, the
risk theoretically should decrease or go away. The problem is that metal stents
are not always absorbed. In theory, biodegradable stents should be.
"The
panacea would be a drug-eluding biodegradable stent where the drug is released
into the vessel wall before
the stent gets absorbed," he said. "This would lower the re-stenosis
or re-blockage rate, yet eliminate risk of heart attacks or blood clot,"
Kaplan said. "From a technical standpoint, this particular stent is
providing a similar risk to a bare-metal stent."
The new
study is "helping us feeling more comfortable that this is a good line of
research to pursue and that there is no special concern about hidden dark sides
with this biodegradable stent," added Dr. Kirk Garratt, clinical director
of interventional cardiovascular research at Lenox Hill Hospital in New York
City.
More information: What is a stent? Learn more from the U.S. National Heart,
Lung, and Blood Institute.
Denise
Mann
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