Interventional technologies in stroke, heart disease treatment.

ORLANDO, Florida -- Interventional therapies, and drug-eluting coronary stents in particular, have had a major impact on the management of cardiovascular disease over the past decade. In 2003, the number of patients treated with coronary stents worldwide is projected to be three-fold higher than the number of patients who have coronary artery bypass graft surgery. In addition, the scope of interventional therapy is continuing to expand to include methods to treat or prevent stroke, techniques to repair vascular aneurysms, and stenting to treat an increasingly broad spectrum of peripheral vascular disease.

At the 2003 meeting of the American Heart Association (AHA, Dallas, Texas), held here in early November, researchers described a number of new developments in interventional therapy that are expected to drive continued expansion of the cardiovascular device market. Drug-eluting stents continue to attract the most attention, as users refine their approach for patient selection to limit the cost impact, and new devices enter the market, increasing the level of competition. However, other applications of stents, such as stenting of the carotid arteries to prevent stroke, peripheral vascular stenting in challenging vessels such as the superficial femoral artery, and new stent designs for the treatment of bifurcated and other complex lesions, also represent important advances in interventional technology.

Other important advances were described at AHA in the areas of interventional treatment of heart defects including heart valve disorders, treatment of cardiac rhythm defects and new approaches for noninvasive diagnosis of vascular disease. One emerging area of technology development is the use of nanotechnology, including nanoparticles and new surface structures for drug-eluting stents, that may play an important role in a number of clinical applications including imaging of vulnerable plaque, delivery of anti-restenosis drugs and advanced techniques for revascularization. A number of new ventures have emerged that are pursuing the use of nanotechnology in the cardiovascular device field, indicating that opportunities still exist for new technology-based companies in the market.

Advances in vascular stent technology

Stents for peripheral vascular and visceral applications have been available for more than a decade, mainly for applications in the larger-diameter vessels. However, the range of applications, and the size of the market opportunity, is now poised to expand as a result of advances in stent and related technologies. Carotid stents have generated significant interest as a means to treat stenosis and prevent stroke. A number of newer products and products under development have features that are expected to allow physicians to perform more peripheral vascular stent procedures, including improved mechanical flexibility, companion embolic protection devices to avoid procedure-related strokes and lower-profile devices that allow direct stenting to be performed, further reducing the risk of embolization during stent procedures.

In addition, new techniques for carotid plaque characterization promise to improve risk stratification of patients. More than 16,000 patients have now been treated with carotid stents worldwide in clinical studies, including about 11,000 in the Global Carotid Artery Stent Registry. As shown in Table 1, the number of patients treated annually is expected to increase substantially over the next three to five years, as carotid stents and embolic protection devices for use in carotid stenting begin to enter the market in the U.S. sometime in 2004.

At present, the standard treatment for carotid artery stenosis is carotid endarterectomy, a surgical procedure that typically has a high success rate and a relatively low adverse event rate when performed by experienced surgeons. However, as described by Gary Roubin, MD, of Lenox Hill Hospital (New York) at the AHA sessions, the most recent studies using the latest generation of carotid stents and embolic protection devices have demonstrated that carotid stenting can provide outcomes that are at least equivalent to those achieved with surgery, but with less-invasive techniques. In the lead-in phase of the Carotid Revascularization Endarterectomy vs. Stenting Trial (CREST), for example, which is employing the Accunet embolic protection filter and Acculink Carotid Stent System from Guidant (Indianapolis, Indiana), adverse events in the stent group were lower than expected, at 3.4% …