International Circulation: What are the major characteristics of any future ideal stent platforms? Should we focus on the polymer， stent structure design， other factors such as antihyperplasia agents?
Prof. Windecker: In a session earlier this morning， I pointed out the major shortcomings of the technology that we have today. The first area that can be improved is efficacy because we have seen in trials comparing CABG versus percutaneous coronary intervention in patients with multivessel disease that PCI still remains inferior， indicating that efficacy remains an issue. There are also concerns that the earlier generation of DES may predispose to some type of late catch-up， which means that they are very efficacious up to one year but that advantage may be lost or diminished during longer term follow-up. Thirdly， is the area of patients with stent overlap where we clearly need improvement. These factors all relate to efficacy， but perhaps more importantly is the safety outcome. We have identified the problem of very late stent thrombosis with the early generation of DES， which is a multifactorial process， but probably related to some type of inflammatory reaction and pathologic vessel remodeling. Advances such as biodegradable polymers， polymer free drug release， or completely biodegradable stents are certainly advances that have the potential to improve long-term outcome.
International Circulation: The purpose of designing biodegradable stents is to resolve problems including both early intimal hyperplasia of BMS and late in-stent thrombosis of DES. How far are we from solving these problems? What is the present reality with biodegradable stents?
Prof. Windecker: At present， we can say that the biodegradable polymer-based DES are at least as safe and effective as durable polymer DES. However， to date there has been no study indicating that they are safer but there are some studies indicating that there may be a trend towards a lesser degree of stent thrombosis. Having said this， we must realize that even if we were to use BMS as a comparator， there are rare cases of very late stent thrombosis as it has been realized that within the stents there can be new atherosclerosis. Therefore， we need to realize that as long as we use metallic drug-eluting stents there will be very low level of stent thrombosis.
For the future， to definitively answer the question whether biodegradable polymer-based DES are superior there must be large scale trials. The reality is that most of the future DES are biodegradable polymer-based.
International Circulation: What do you think of the potential of the endothelial progenitor cells (EPC) stent， which is not a true DES? Is this a novel strategy for the development of a future intravascular stent?
Prof. Windecker: It is not a novel technology anymore and there have been several studies indicating the safety and efficacy of this device. What we can say at this time is that in terms of efficacy it is quite similar to a BMS and for this very reason the next evolution of this technology is to combine the anti-CD34 antibodies， which capture the endothelial cells， with sirolimus drug release. So it has been realized that the EPC capturing capability alone does not suffice and it must be combined with drug release and that is currently under investigation.
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