Tuesday, January 11, 2011


This morning, I have just received news from Abbott Vascular and I also read the initial reports that ABSORB, has been given CE mark approval in Europe.
ABSORB is a drug eluting, bioabsorbable stent maufactured by Abbott Vascular, for the treatment of CAD. Just to re-cap. DES ( drug eluting stents ), are drug coated stents used in angioplasty to lessen re-stenosis as the drugs coated on the stents are anti-proliferative. The first generation were thick surgical grade, stainless steel, of slotted tube design. They were either coated with sirolimus ( JnJ Cordis ) or with paclitexal ( Boston Scientific ). These were thick and bulky and also has a higher MACE numbers. The second generation were thin struts cobalt chromium stents coated with -limus, and they were more deliverable and had lower MACE numbers. However, interventionist were still worried about the 0.4% late stent thrombosis rates that these DES were producing, maybe because some of the second generation DES still had a polymer coating. The later versions of the second generation DES had biodegradable polymers. This seem to give better MACE numbers.
Over the last 4 years, Abbott Vascular had been working on a DES, made of polylactide, which is fully bio-absorbable. Polylactide, is the polymer fibre that bioabsorbable sutures are are made of. These stents were coated with their proprietary "everolimus" drug. It is implanted just like any other DES, and over the next few weeks the drug gets eluded, and over the next 6 months or so, the polylactide scaffolding gets absorbed, so that by 2 years, there will be no more metal scaffolding and the vessel is said to recover its physiological function. The clinical trial on the first 30 patients ( cohort A ) is now 4 years on, and the results were good. The cohort B has reached 3 years, and the results also were good. There were no late stent thrombosis out to 3 years, and the MACE at 3 years is still 5%, like all the other 2nd generation DES.
I am sure that based on the ABSORB results over 3 years, and also with a bigwig like Patrick Surreys leading the study, the ABSORB stent has now received its CE mark, meaning that it is safe for clinical use. I have been told by Abbott this morning that they will be launching it in Europe by end 2011, and maybe by then or by early 2012, we should get ours. Of course more studies are needed. It is safe, but is it as good as the second generation, bio-degradable polymer DES?
Although the idea is very novel ( some patients have "metal phobia" ), I am a little concern that there maybe a slightly higher rate of re-stenosis, when compared with 2nd generation DES, although it did not show in the ABSORB study. We need to see more numbers. I am severely biased because of the early poor results with the old bioabsorbable Tamai stent and also the first generation magnesium bioabsorbable stent by Biotronik. Of course the obvious advantage of the ABSORB stent is that we do not need long term dual anti-platelet therapy, as after 2 years, there is no more metal.
As always, what is the cost? Is the cost benefit ratio adequate for widespread use, or must it be for niche use. Well, I am awaiting end 2011, to see what Abbott declares. I don't think it will be cheap.

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