DO DES ( DRUG-ELUTING STENT ) LAST FOREVER?

Whenever I brief patients and relatives before obtaining consent for angioplasty and stenting, they often ask me how long do the DES last? Do DES last forever?. I will always reply that our experience and the worldwide experience with DES is 6 years and 8 years respectively. That is because there was no clinical trial longer then 5 years in a clinical practice type patient. The first clinical trial on DES, the RAVEL trial ( now 7 years ) is on the ideal patient. The everyday type patient trial which I was alluding to was the SIRIUS trial, which has just published their 5 year follow-up data. And everything continues to be good. SIRIUS of course compared CYPHER ( DES by Cordis ) with their bare metal stent. There was a slight increase rate of TLR in the Cypher arm annually, but this was much lower than the bare metal arm.
Well, the April 2009 issue of the Journal of the American College of Cardiology: Cardiovascular Interventions, carried a very interesting article by the German workers of the ISAR ( Individualized Drug-Eluting Stent System to Abrogate Restenosis ) group. Dr Robert Byrne et al, followed up 2030 patients who had three types of DES implanted. Gp1 received the Cypher stent, Gp2 the Taxus stent and Gp3 the ISAR stent. The ISAR stent is a proof of concept, experimental DES. This is a premounted, sand-blasted, stainless-steel, microporous stent that is coated on-site with rapamycin (sirolimus). Basically, you have the prepared stainless steel stent base and you coat on the rapamycin at the cath lab. ( interesting ). Therefore, the ISAR stent has no polymer. All patients had angiogram at 6 and 24 months. Slightly over 10% of patients had TLR before 2 years. This group was equally divided among the 3 groups ( shows that the on-site prepared ISAR was just as good as the branded DES ). The LL was 0.25 for Cypher and about 0,46 range for Taxus and ISAR. This was not statistically significant. What was interesting was that at 2 years, the additional LL was 0.17 for Cypher, 0.13 for Taxus and ),01 for the ISAR stent.
Now this is a very important finding. The cypher and Taxus stent both had polymers, while the ISAR stent is polymerless. It means that with time, some of the effectiveness of DES with polymers may be loss. The polymer seem to excite some reaction and may promote restenosis. If this study is correct then DES with polymer coating, does not last forever. Those without polymers, may. But at this moment, we do not have data on polymerless DES with two year followup on a clinical trial, comparable basis. The two polymer absorbable DES that I know of is the Excel stent and the Biomatrix stent. We have just seen the 2 year follow-up of the Excel stent published, and it looks very good. But the followup was 18 months and it is also essentailly an observational study. I have yet to see the Biomatrix data at two years.
When I read this paper, I was also very impress that you could make the DES in the cath. lab. Can you imagine, I could have abase prepared stent ? stainless steel ? cobalt chromium, or any other material, and in the cath. lab. coat which whichever drug that is good for that patient subset, then I can individualise the DES to my patient. Making a polymerless DES is not so difficult after all. It this true?
I am also aware that this is essentially an observational study. We will need a large multicenter trial to confirm this finding. But it is important to note that the two second generation DES, namely the Endeavor and XienceV, both show in their three years followup, that the MACCE rates from 2-3 years are both flat, meaning that there is no late catch-up.
So do DES last forever? Very like, the DES with polymers, does not, and maybe the polymerless ones do?? We need more data.