A Medical Device Daily

Drug-eluting stents (DES) have become a treatment of choice for arthrosclerotic disease because they are effective in reducing the rate of restenosis. But a series of recent studies linking drug-eluting stents to late stent thrombosis has doctors and patients concerned about the use of these devices, according to a presenter at the recent VEITHsymposium in New York.

Renu Virmani, of Georgetown University (Washington) and medical director of CVPath, the International Registry of Pathology, reported findings regarding late stent thrombosis in the only two stent devices currently approved by the FDA, Cordis's (Miami Lakes, Florida) Cypher and Boston Scientific's (Natick, Massachusetts) Taxus.

Virmani examined the pathology reports from 83 patients with 117 lesions, finding several anatomical factors that predispose patients to stent thrombosis. When a stent is placed in a bifurcated lesion, which occurs when a single vessel branches into two, the increased wear and tear on the device creates a greater chance for complications to arise. In addition, if the stents required to treat a lesion were excessively long or required overlapping, the incidence of thrombosis also increased.

Virmani found different problems associated with both Cypher and Taxus stents. In Taxus stents, a protein in blood that aids in clotting, fibrin, was more frequently deposited around the stent site. Cypher stents were more likely to cause inflammation and hypersensitivity in patients and more prone to the severe fracturing associated with restenosis and late stent thrombosis.

The VEITHsymposium, sponsored by the Cleveland Clinic, was started by vascular surgeon Frank Veith, MD, also of the Cleveland Clinic, and was attended by about 2,000 people.

In other news from the symposium:

  • Carotid angioplasty with stent (CAS) placement is an effective alternative to carotid endarterectomy, but been hampered by concerns about intraoperative cerebral embolization and complications associated with the use of cerebral protection devices. Franco Perona, MD, professor of radiology at the University of Milan and chief of the department of radiology and interventional radiology at I.R.C.C.S. Istituto Ortopedico Galeazzi (also Milan), reported evidence demonstrating that high-risk patients can be successfully treated with CAS without the use of cerebral protection devices. Based on results from a retrospective study of 400 patients, use of CAS without protection devices produced a low complication rate comparable to those observed with protection devices and within the limits recommended by the American Heart Association (Dallas) for CEA.
  • New international guidelines on the management of peripheral arterial disease (PAD) recommend an expanded role for endovascular therapies in the treatment of more complex femoropopliteal lesions, reported Marc Bosiers, MD, of AZ St. Blasius Hospital (Dendermonde, Belgium). The first report of the TransAtlantic Inter-Society Consensus (TASC I) on the management of PAD, published in 2000, recommended endovascular therapies as procedures of choice in patients with morphologically focal type A lesions of the iliac or femoropopliteal arteries, and surgery for their opposite-type D lesions-which are diffuse, extensive and multilevel. These recommendations remain the same in TASC II, although the length of stenosis that qualifies lesions has been expanded. Bosiers credits the changes with recent stent design improvements that focus on decreasing stent fracture rates, thereby improving patency (blood flow). "Older-generation stents, also nitinol ones, seemed not to be able to cope with the complex and continuous motion of the femoropopliteal arteries, and this has serious impact on the outcome of the intervention. Considering first preliminary clinical results using newly designed stents indicate decreased stent fracture rates," he said. "It is too early to predict the impact of the use of bioabsorbable and drug eluting stents on the outcome of peripheral endovascular interventions. Ongoing clinical trials investigating these technologies, will give us first indications on their value," Bosiers said.
  • Endologix (Irvine, California) reported that favorable Powerlink System clinical data were featured in two presentations by Dieter Raithel, MD, of Southern Clinic (Nuremberg, Germany), and Jeffrey Carpenter, MD, of the University of Pennsylvania School of Medicine (Philadelphia). Raithel reported that Powerlink's design characteristics make it superior in treating patients with aneurysm anatomy deemed unsuitable for other stent grafts. His conclusion was based on his experience with 1,492 stent graft procedures, including 492 Powerlink System cases over an 8.5-year period. He said the Powerlink System is a critical component of his armamentarium that allows him to treat more than 90% of all eligible AAA patients with a stent graft. Carpenter reported on his experience using the bifurcated Powerlink System as the primary treatment device in conjunction with larger commercially available accessories to treat AAA patients with wide aortic necks. He concluded that the Powerlink bifurcated stent graft's long main body and the small french size of its delivery catheter facilitated this composite approach. "We believe the positive experience of these leading clinicians provides growing clinical support that the Powerlink System is capable of treating the continuously increasing number of patients seeking minimally invasive AAA repair options," said Paul McCormick, president and CEO of Endologix. "While we are seeing strong growth in the use of stent grafts through better devices and favorable demographics, open repair remains a significant clinical alternative for many clinicians due to the limitations and results of the early-generation devices."