What Is The TCT?
Every fall since 1988, audiences of interventional cardiologists have gathered
in Washington, DC for the annual TCT (Transcatheter Cardiovascular Therapeutics)
Symposium. This year's meeting, attended by an estimated 12,000 physicians,
spanned 5 days and included scores of presentations, dozens of live case demonstrations
broadcast from around the world, the announcement of a dozen late breaking
clinical trials, exhibits from over 300 device and other manufacturers, and
special evening symposia -- all presented by an international faculty of hundreds
of interventional cardiologists and their radiological and surgical colleagues.
The event receives substantial support from the medical industry and serves
as a showcase for the latest developments in interventional vascular therapy. |
|
TCT
symposium is held annually at the Washington Convention
Center |
Quick Summary
While no revolutionary announcements were made during the meeting,
the information and presentations did clarify certain directions
in therapy, directions that will have significant benefit to
patients:
- Positive results for drug-eluting
stents (a.k.a coated stents or medicated stents)
continued to
be reported -- the benefits of these devices are proving
to be long-lasting, or what interventionalists call "durable",
and the devices are expanding in application
-- good
results
were
shown
for complex
coronary
cases, and
in patients with diabetes, patient populations previously
not considered optimal for stenting;
- Interventional catheter-based therapy
is expanding to treat vascular disease outside of the heart
-- very positive
reports on carotid stenting (opening up the arteries
in the neck
that feed the brain) with results comparable or better
than the most commonly-used "open" surgical procedure of
carotid endarterectomy;
- Several novel devices for specialized
situations, such as the SafeCross® infra-red/radio
frequency catheter that allows the
penetration of total occlusions in the coronary arteries;
- Results of several studies that put to rest certain therapies/devices,
such as brachytherapy, or intracoronary radiation, that
have not wound up being as effective as originally thought.
|
Taxus Stent
(courtesy Boston Scientific) |
|
DES
(Drug-Eluting Stents)
Clearly the most important recent advance in the field
of coronary angioplasty has been the drug-eluting stent. Currently
two such stents are approved for use in the U.S.: the Cypher™ from
Cordis/Johnson & Johnson and the Taxus™ from Boston
Scientific. A number of studies and clinical trial results reported
continued efficacy for these devices which reduce the restenosis
or reclosing of the coronary artery after stent placement from
20-30% down to single digits. While the differences in these
studies are closely watched by investors, marketing departments
and others who have vested interests in the specific manufacturing
companies, these differences pale when one compares the overall
performance of all drug-eluting stents to the older bare metal
stents. |
DES: Multivessel Disease
Patrick Serruys, MD, of the
ThoraxCenter in Rotterdam presented the results of ARTS II
(Arterial Revascularization
Therapies
II).
The original ARTS I study, done in 1997 before drug-eluting
stents were available, compared bypass surgery to bare metal
stents.
ARTS II added in a patient component that received the Cypher
stent. All patients were treated for multiple vessel coronary
disease,
a situation in which bypass surgery is often recommended over
angioplasty.
However, the MACE (Major Adverse Coronary Event) rate after
6-months showed that only 7% of the Cypher group suffered
an event, as
compared to 9% of the surgical group and 20% of those who had
bare metal
stents. A MACE is defined as heart attack, stroke, death, or
repeat surgery/angioplasty.
DES:
Diabetic Patients
Dr.
Keith D. Dawkins of Southampton General Hospital in England
began his evening presentation with a frightening
statistic, showing a five-fold increase in diabetes mellitus
from 1985 to 2000, increasing to a ten-fold increase predicted
over the next twenty years.
He called diabetes nothing less than a "pandemic".
And diabetic patients are at significantly
greater
risk of developing
coronary
artery disease. The conundrum has always been, however, that
interventional therapies, such as angioplasty, have been less
successful for diabetic patients
than for non-diabetics.
Restenosis
rates
(30-40%)
and
other complications
have caused many physicians to recommend open heart surgery instead. |
|
Diabetics Worldwide
in Millions
-- International Diabetes Federation |
However,
drug-eluting stents may be changing that scenario. Dr. Manel
Sabaté of Hospital Clinico San Carlos, Madrid,
Spain presented the DIABETES trial which compared the Cypher
to a bare metal stent
in diabetic
patients. Restenosis
rates were only 7.7% for the coated Cypher stent, while the
bare metal stent reclosed an expected 33% of the time. Data
from the e-Cypher registry also confirmed
good results in diabetic patients. Dr. Giulio Guagliumi, of the
Ospedali Riuniti de Bergamo in Italy, stated that the TLR (target
lesion revascularization)
for diabetics was only 1.67% higher than that for non-diabetic patients.
As for the Taxus coated stent, Gregg Stone, MD, of Columbia University
Medical Center in New York presented two-year followup for the
Taxus IV
study, showing diabetic patients with a TLR rate of 8%. The bottom
line here is that drug-eluting stents seem to have great benefits
for diabetic patients. Certainly more studies need to be done and
there are other measures which need to be considered, but it
seems that
the drugs on these stents interrupt the response that
causes restenosis in diabetics.
"Stents
have narrowed the gap...Drug-eluting stents, now with
more data coming, should erase the differences."
-- Martin Leon, MD |
|
DES vs. Surgery
Additionally,
the Taxus studies showed that better than delaying the onset
of
restenosis,
the
drug-eluting stents seemed to
be preventing it -- the benefits of the Taxus stents actually
increased over the two-year study period. All this new research
prompted Dr. Martin Leon, organizer of the TCT, to state, "Stents
have narrowed the gap in mortality benefit in CABG [bypass
surgery] vs. PCI [angioplasty]. Drug-eluting stents, now with
more data coming, should erase the differences.” And
in an evening symposium, co-organizer Dr. Gregg Stone speculated
whether, if results from these future studies were comparable
to the early indications, at some point in the not-too-distant
future, these minimally invasive procedures might end up replacing
most bypass surgery. |
Carotids and Beyond
On the heels of the FDA approval of Guidant's RX ACCULINK™ Carotid
Stent System and RX ACCUNET™ Embolic Protection System last
month, two
studies on carotid angioplasty/stenting were presented. In this
procedure, the artery
in the neck that
leads
to the brain,
is opened in much the same way that a coronary angioplasty is
performed. Today the carotid is usually opened surgically
in an procedure called carotid endartarectomy.
But in many centers, stenting is now being performed, especially
in compromised patients who may not do well in surgery. The clinical
trials presented were named CABERNET and the
MAVERIC II (suffice it to say that these acronyms
refer
to
the
devices
used). The
CABERNET trial was a combination of the NextStent™ by EndoTex
and the FilterWire™ EX/EZ made by Boston Scientific. The
MAVERIC trial utilized the Exponent stent and the GuardWire™ balloon
occlusion system, both made by Medtronic. In each system, a stent
is expanded in the carotid artery while a filter or balloon prevents
any debris loosened by the angioplasty from travelling to the
brain. The results exceeded expectations and showed the minimally
invasive carotid stenting to be equal or better than conventional
surgery. There are still many questions -- the sample size of
the studies was relatively small -- but the results are superior
to similar studies done over the past few years, implying that
doctors are getting better at performing the procedure, AND that
the devices themselves are being improved by the manufacturers.
Angioplasty/stenting in the kidneys and the legs
were also discussed -- as was an even newer application of endovascular
therapy, the treatment of AAA (Abdominal Aortic Aneurysm) with
stent grafts. The move in medicine today is clearly away from conventional
open surgery and more and more towards endovascular or interventional
solutions (angioplasty and stenting). For more on this evolution/revolution,
view our documentary (now on DVD) "Vascular Pioneers:
Evolution of A Specialty"
at VascularTherapy.Org.
Intracoronary Radiation Studies Show
No Benefit
As a check to over-enthusiasm about new technologies that
have not yet been studied long-term, a sobering study was
presented. The five-year follow-up from the Gamma-1
study of the Cordis CHECKMATE™ Gamma Radiation System (brachytherapy) showed
disappointing results for reducing in-stent restenosis (stents that have been
clogged). While the results at two-years looked somewhat positive, over five-years
the curves of the patients treated with radiation and placebo converged, so that
there was no perceived benefit. The results were not a great surprise to many
cardiologists and the use of intravascular radiation has been dwindling (Guidant
discontinued its GALILEO® Intravascular Radiotherapy System back in April
2004). |
|
radiation catheter
(courtesy Cordis) |
Dr. Leon did not think the same problem
will be found in drug-eluting stents. He stated to theHeart.org's
HeartWire, "We view vascular
brachytherapy
as if you're basically exploding a bomb in the coronary arteries...You
eternally alter the biology of the vessel wall, you affect endothelialization,
you affect platelet absorption...and you affect the
healing response...We view DES not as a bomb, but more as
a laser beam...We think that the effects are shorter,
more specific, and we're hopeful that the effects will be much
more durable." He concluded that in his hospital,
"We have essentially ceased using vascular brachytherapy."
For the latest
news about developments in the field, go to our Drug-Eluting
Stent NewsCenter. We welcome your
comments on this article.
Source: Angioplasty.org, October 11,
2004
CONTACT: Burt
Cohen, Producer of Angioplasty.org
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