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

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