Abbott announced the start of SPIRIT Small Vessel, a clinical trial evaluating a 2.25 mm size of the Xience V Everolimus Eluting Coronary Stent System. The 2.25 mm stent system would offer physicians an option for treating coronary artery disease in narrower vessels that is based on the proven efficacy, safety and deliverability of Xience V.

In July 2008, Xience V was launched in the United States, where it quickly became the market-leading drug eluting stent. The addition of a 2.25 mm size would complement the broad range of Xience V lengths and diameters. Upon US Food and Drug Administration (FDA) approval of the 2.25 mm stent system, the device will be called Xience Nano in the United States. The Xience V 2.25 mm stent system received CE Mark (Conformité Européene) approval and was launched in various countries in Europe, Asia and Latin America in March 2008.

"Treatment of lesions in small coronary vessels is often complex and associated with higher rates of complications. Being able to deliver a stent accurately to the diseased area of the vessel is crucial for successful treatment," said Marco Costa, M.D., Ph.D., director of Invasive Services, and director of the Centre for Research and Innovation, Harrington-McLaughlin Heart and Vascular Institute, University Hospitals, Case Western Reserve University, and principal investigator of the SPIRIT Small Vessel trial. "Given the strong clinical performance and ease of use of Xience V, a smaller stent system would significantly enhance the treatment options for patients with coronary artery disease in small vessels."

The SPIRIT Small Vessel trial is designed to study 250 patients at approximately 50 centres in the United States. The primary endpoint is a composite measure of cardiac death, heart attack (target vessel myocardial infarction) and target lesion revascularization (repeat procedures on the treated vessel) at one year.

Observational data supporting the safety and efficacy of Xience V in the treatment of coronary artery disease in small vessels was presented at the 2008 Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium in October. James B. Hermiller, M.D., director, Cardiac Catheterization Labs, The Care Group at St. VincentHospital in Indianapolis, and an investigator of the SPIRIT III trial, presented subgroup data from the SPIRIT III trial comparing Xience V to the Taxus Express2 Paclitaxel-Eluting Coronary Stent System (Taxus) in patients with small vessels. In this subgroup analysis, patients were treated with a 2.5 mm stent system and had an average reference vessel diameter of 2.36 mm.

"In the SPIRIT III subgroup analysis, Xience V performed extremely well in small vessels. Compared to Taxus, Xience V reduced in-stent late loss, or vessel re-narrowing, by 80 percent eight months after the procedure, and reduced major adverse cardiac events by 74 percent at nine months," said Dr. Hermiller. "When you consider these trends, the availability of a smaller Xience V stent system specifically designed to treat lesions in small vessels has the potential to significantly improve patient care."

The Xience V drug coated stent is used to treat coronary artery disease by propping open a narrowed or blocked artery and releasing the drug, everolimus, in a controlled manner to prevent the artery from becoming blocked again following a stent procedure. Xience V is built upon Abbott's market-leading bare metal stent, the Multi-Link Vision Coronary Stent System. The Vision platform is designed to facilitate ease of delivery, making it easier for physicians to manoeuvre the stent and treat the diseased portion of the artery.

The Xience V stent is available on both over-the-wire (OTW) and rapid exchange (RX) delivery systems. Rapid exchange is the most widely used type of delivery system because it provides physicians additional flexibility to work as single operators during stent procedures.

Xience V was approved by the FDA in July 2008 and launched in Europe and other international markets in October 2006. XIENCE V is an investigational device in Japan and is currently under review by the Ministry of Health, Labour and Welfare and the Pharmaceuticals and Medical Devices Agency.

Abbott supplies a private-labelled Xience V to Boston Scientific called the Promus Everolimus-Eluting Coronary Stent System. Promus is manufactured by Abbott and supplied to Boston Scientific as part of a distribution agreement between the two companies.

Everolimus, developed by Novartis Pharma AG, is a proliferation signal inhibitor, or mTOR inhibitor, licensed to Abbott by Novartis for use on its drug eluting stents. Everolimus has been shown to inhibit in-stent neointimal growth in the coronary vessels following stent implantation, due to its antiproliferative properties.