Monday, December 10, 2007

The state of DES at end 2007

We started to use the first DES, the Cypher stent (JnJ cordis) on 28th May 2002. The Cypher was FDA approved in 2003, and the Taxus (Boston Scientific) was approved in 2004. These two must form the 1st generation DES. From these two, we have learned much, including an excellent short term (1 year) result. The SAST (subacute stent thrombosis) rate of 1-4% and a restenosis rate of <5%. This was very good compared to the bare metal stent which had figures of 1-4% and 15-20% respectively. ( * Thrombosis is blood clotting, and stent thrombosis is blood clots forming in stents ).

There was a time from 2003 to 2006 when we felt that we could DES everything. DES was then proclaimed as a revolution in CAD treatment. The cliche then was that everyone (meaning everyone who could afford) should get a DES. DES usage then climbed to almost 95% in some institution, both at home and abroad. Then came the fall of 2005, and the summer of 2006, when we began to hear murmurings of problems with DES. The Europeans began to produce reports of late and very late stent thrombosis with DES. The shares of JnJ and Boston duly fell. DES usage declined, both at home and abroad. DES usage in some centers fall to almost 50-60%.
Now, the summer and fall of 2007 brought some silver-lining. Many reports began to appear, which showed that DES stent thrombosis was not unique to DES but was also seen, in similar proportions, with bare-metal stents. In fact, the FDA had at a December meeting, come to the same conclusion. They identified that when DES was used as labelled by FDA, there are no problems. It is the off-label use that is of some concern. Looks like the clouds are lifting on the DES-stent thrombosis issue. In short, there are no problems with DES use if it is used as labelled. When the cardiologist wishes to use it off label, they must be more circumspect and think twice. The use of plavix had gain prominence, as many of the DES-thrombosis problem maybe due to premature discontinuation of plavix.

The other good news in Novenber, December 2007, is the FDA advisory panel approval of two new DES, namely the Endeavor stent (Metronic International), and the XienceV stent (Abbott Vascular). These two stents can be called a second generation DES. Their stent platform is cobalt chromium base (as opposed to stainless steel base for the cypher and taxus). The advantage of cobalt chromium is that is a very strong alloy, allowing the company to make the stent struts very thin and low-profile, while retaining it's radial strength. This translated clinically into a stent with low stent restenosis rate (even on bare-metal), a more deliverable stent and probably a stent with lower stent thrombosis. The plain (non-drug coated) bare-metal cobalt chromium stents had half the restenosis rate of the old stainless steel bare-metal stents. In fact the plain (non-drug coated) cobalt chromium stents had a restenosis rate of only twice that of DES. The results so far of the cobalt chromium DES shows that there seemed to be less stent thrombosis and a lower restenosis rate. Looks like the second generation DES is definitely better than the first generation. What more, there is no increase in price. In fact, the first generation, were a bit more expensive. This is thus good news for the patients.

I am sure that with more innovations, the third generation DES will even be better. But first, I think that we will be seeing more second generation DES coming to our shores soon. So much better for our patients. I hope that the price will come down further.

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