DES Summit Part I
Current DES Platforms
In an afternoon session update on current worldwide DES technology, Dr Eberhard Grube, Germany, presented an overview of DES usage past, present and future as an introduction to a series of lectures in support of the “Big Four” (CYPHER, TAXUS/TAXUS Element, ENDEAVOUR/RESOLUTE and XIENCE V).
In an afternoon session update on current worldwide DES technology, Dr Eberhard Grube, Germany, presented an overview of DES usage past, present and future as an introduction to a series of lectures in support of the “Big Four” (CYPHER, TAXUS/TAXUS Element, ENDEAVOUR/RESOLUTE and XIENCE V). Following this, session moderator Roxana Mehran was particularly excited to witness a round of presentations from representatives of the Chinese DES platforms. These included FIREBIRD 2, EXCEL, PARTNER, YINYI, TIVOLI and BuMA. Wrapping up the session, an overview of the status of drug eluting balloons, the anti-DES, and panel discussion made for a comprehensive roundup of the current and potential technologies.
Dr Grube mentioned that the value of PCI was well established in the setting of acute myocardial infarction and the procedures superiority over medical treatment. The overwhelming demand for DES dates back to 2003/4 with the SIRIUS and TAXUS 9 month results which very clearly demonstrated the drop in TVR using DES compared to BMS. Over the years, both efficacy and safety have been proven for the use of DES over BMS and with expanding experience and knowledge the technology has evolved into the more complex left main realm. We have seen the progression from first to second generation DES technology and now the newer entities of bioabsorbable coatings (SYNERGY, NEVO) and bioabsorbable stents (metal and polymer).
The reality is though that we have reached quite a high level of efficacy and safety in the PCI field and it may be that things are as good as they can get, but we have been lured on with advancements in technology in terms of stent material, strut design, delivery improvements, abluminal coatings, bioabsorbable coatings, bioabsorbable stents, optimizing of the drug dose and of course stent alternatives. All companies are moving towards making stent struts thinner without losing strength. This is partly attributed to new stent materials such as platinum chromium in which the platinum is two times denser than iron or cobalt alone and increases strength when alloyed with 316L stainless steel. The platinum is fully incorporated in the alloy rather than just a coating which allows for flexibility, radio-opacity superiority compared to other stents and even though it is thinner, no radial strength is lost.
The role of polymer coatings is to deliver drugs in the short term and is not needed long term. The goal is to maintain efficacy and acute performance of these devices and to reduce late events and dual antiplatelet therapy requirements while minimizing drug load and total coating weight. Reservoir technology as used by the NEVO stent, the Biolimus biodegradable drug/carrier of the BioMatrix stent and the abluminal bioabsorbable polymer and drug of the SYNERGY stent are examples of the latest in drug delivery. The thickness and weights of these coatings have been getting thinner and lighter.
Moving on, the bioabsorbable stent means that the vessel scaffolding is required only transiently during the time of the implant such that there is no permanent implant remaining meaning there is no stimulus for chronic inflammation and future re-intervention (PCI and CABG) should be facilitated. Examples of these platforms are BVS, REVA, BIT and Igali-Tamal. Proving the safety advantage for bioabsorbable scaffolds/stents is very difficult, requiring large scale trials with long duration follow-up and at best are likely to show non-inferiority. For the time being, “proof of advantage may require patience”.
In conclusion, Dr Grube said that DES technology advances can have a significant clinical benefit from previous generations, particularly in more challenging patient subsets (small vessels and long lesions) and the future is very promising.