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Spirit First - Another hurdle is cleared.

© Europa Edition 2005. All rights reserved. Drug eluting stents (DES) are now the default therapy for patients undergoing percutaneous coronary intervention (PCI) for native vessel coronary artery disease. Three DES are currently available, having shown clinical and angiographic superiority over bare metal stents in large randomized clinical trials1-3. These studies have suggested that each of the DES components – the stent platform, the elution polymer, and the specific antiproliferative agent – may provided particular advantages in different clinical scenarios. The CYPHERTM (Cordis Corporation, Miami Lakes, FLA) stent is comprised of a stainless steel stent platform, a durable co-polymer mixuture of polyethylene-co-vinyl acetate (PEVA) and poly n-butyl methacrylate (PBMA), and the G1 cell cycle inhibitor sirolimus, which elutes completely from the polymer within 30 days1. The TAXUSTM (Boston Scientific, Natick, MA) stent employs a stainless steel stent platform, a polyolefin polymer derivative, and microtubular stabilizing agent paclitaxel, whose two-phase 30-day polymeric release kinetics that provides its antiproliferative effect2. The ENDEAVORTM stent (Medtronic, Minneapolis, MN) utilizes a cobalt chromium stent platform, a durable, antithrombotic, phoshorylcholine (PC) encapsulated coating, and another G1 cell cycle inhibitor, zotarolimus, which elutes from the PC coating over several days4. Results from large (> 1,000 patients) randomized trials show that these DES reduced clinical events by 50-70% compared with bare metal stents1-3. The benefit appears similar in a variety of patient and lesion subsets5-7, including those with diabetes8, long lesions, and small vessels7. Deliverability becomes an important performance measure in patients as the lesion complexity increases, and newer DES may provide a particular advantage over prior stent designs, and may address the small (<5-10%) but lingering failure rate associated with conventional DES use. Novel drug eluting stents A number of important lessons have been learned as alternative DES systems have been evaluated. Some DES programs have had limited clinical efficacy9, likely do to very rapid drug release or ineffective antiproliferative agents, and others have shown potential toxicity, such as paclitaxel eluting stent using a durable polymeric sleeve that was associated with high acute stent thrombosis rates10 and delayed restenosis11. The elution of actinomycin-D in the ACTION trial found higher than expected restenosis rates and aneurysm formation in some patients treated with this DES12. The current study reports very favorable one year angiographic and ultrasound results associated with the use of the XIENCETM stent. The components of the XIENCETM stent provide potential improvements over prior generations of DES. The cobalt chromium rapidexchange VISIONTM stent (Guidant Corporation, Santa Clara, CA) may provide enhanced deliverability and radiopacity with thinner strut filaments. The durable polymer appears to provide sustained drug elution and vascular compatibility in these early studies. The antiproliferative agent, everolimus, has proven safety a much higher systemic doses in patients following renal transplantation. Compared to bare metal stents, the XIENCETM DES system is associated with significantly less intimal hyperplasia at one year using a variety of angiographic and ultrasound parameters. This is an important hurdle to clear, and this system has the “green light” to proceed with larger, more definitive clinical trials. Other novel systems that alter one of the three components of the DES are also undergoing evaluation. Bioabsorbable polymeric coatings may obviate the potential problems associated with durable polymer implantation. The Biosensors STEALTH stent, the FUTURE DES program using everolimus13, and the Conor PISCES stent using