Current PCI Limitations

Although significant advances have been made with drug eluting stents, we believe that current stent designs and methods of delivery limit both their effectiveness for patients and the efficiency of physicians treating CAD, and can result in increased costs for healthcare providers. Current commercially available stent systems include stents with fixed-lengths of up to 33mm, and require a separate device for each stent used. These characteristics of existing technology lead to the following limitations:

• Inability to Customize Treatment Options In Situ
  The effectiveness of drug eluting stents has caused physicians to expand their use beyond the treatment of single or discrete lesions to the treatment of long lesions and multiple lesions. Using currently available technologies, these lesions can require multiple stents, increasing procedure complexity, time and cost. According to a Millennium Research Group survey conducted in May 2006, an average of approximately 1.7 stents were used per stent procedure in the United States, and over 50% of patients undergoing PCI procedures have disease in more than one vessel. Because the procedure is reimbursed at a fixed amount, the cost of the additional stents may be incurred by the hospital.
  
  
• Multiple Catheter Exchanges
  Currently available delivery systems require a catheter exchange for every additional balloon or stent used. In addition to the catheter exchanges required by the use of multiple stents, a procedure may require insertion and inflation of a balloon both before and after placement of each stent. Each catheter exchange increases procedure time, cost and exposure to radiation from additional x-ray imaging.
  
  
• Overlapping of Stents to Cover Long Lesions
  Treatment of longer lesions with current fixed-length stents requires placement of multiple overlapping stents. This can result in reduced therapeutic benefits, and two independent clinical trials have shown this practice is associated with an increased incidence of adverse cardiac events. We believe that the increase in treatment of longer lesions, combined with the length limitations of available stents, has increased the use of this technique, with approximately one in four procedures involving overlapping stents.
  
  
• Inaccurate Placement of Stents
  Geographic miss, or inaccurate placement of stents, results in portions of a lesion remaining exposed, increasing the likelihood of blood clot formation, or thrombosis, and the need for reintervention. We believe that geographic miss can occur due to the difficulty of accurately pre-selecting the necessary stent length and diameter. We believe this is caused by the limitations of two dimensional x-ray images, as well as changes in the shape of the artery that can occur due to device delivery. In addition, we believe that physicians may select shorter stents to ensure deliverability and avoid covering healthy artery side-branches. In Johnson & Johnson's STLLR clinical trial, geographic miss was observed in 44.5% of procedures, resulting in higher rates of thrombosis and reinterventions.
  
  
• Changes in Artery Shape
  The shape of an artery can include a number of bends, and its movement can include a twisting motion with each contraction of the heart. Many current stents can be rigid and stiff along their entire length, in order to hold open diseased arteries, can cause a change in the artery's anatomical shape and may inhibit its natural twisting movement. We believe altering the artery's natural anatomy and limiting its movement may adversely impact the long-term safety of the therapy. An independent clinical trial conducted by the Austrian Wiktor Stent Study Group and European Paragon Stent Investigators, showed that changes in artery shape which occurred following stent procedures were associated with major adverse cardiac events, or MACE.
  
  
• Required Physician Planning and Inventories
  Current drug eluting stent offerings are fixed-length and cannot be adjusted, although the size and shape of lesions can vary significantly. In order to choose the correct stent, physicians can spend considerable time attempting to estimate the size and characteristics of the lesion. Additionally, due to the variability of lesions, hospitals must keep a wide variety of stent sizes in inventory resulting in higher inventory management efforts and costs.