A study published online in The Lancet presented two year data for the bioabsorbable everolimus coronary stent. Commenting on the results, interventional cardiology specialist, Professor Franz Eberli from the University Hospital Zurich (Switzerland) and official spokesperson for the European Society of Cardiology, said:
"In addition to the ABSORB study presenting the longest ever follow up data for a bioabsorbable stent, the investigators used multiple imaging systems, including Optical Coherence Tomography. This technical advance has allowed them to get really detailed images of the intra coronary structures for the first time. What really impressed me was the smoothness of the vessel wall at two years, and images showing the stents had disappeared to a great extent, which was a very promising finding.
The study showed an overall 19 % loss in luminal diameter at 18 months and an angiographic in- stent late loss of 0.48mm at two years. These results fall intermediate between those commonly seen for bare metal stents (which typically have an in stent late loss of 1.0 mm), and drug eluting stents (which typically have an in-stent late loss of 0.15 to 0.3 mm). But the upside of this bioabsorbable stent data is that patients don't appear to be getting any in-stent thrombosis here.
Since in-stent late loss increased by only 0.05 mm between 6 months and two years, the most probable explanation for the in-stent late loss is early recoil after stent implantation. This indicates that this bioabsorbable stent initially is not exerting enough radial force to keep the vessels perfectly open. The challenge facing stent designers is to achieve a balance between sufficient radial strength, and a structure that can be reabsorbed in a reasonable time period. Industry is already acting on this data and looking to produce stronger second generation bioabsorbable stents by developing novel stent designs that retain integrity and radial strength for a longer time period.