thesis
Long Term Follow-up after Drug-eluting Stent Implantation and Early Experience with Endothelial Progenitor Cell Capture Stent
- Publication date
- 14 June 2006
- Publisher
- Intracoronary stent replacement is being used increasingly for the treatment of atherosclerotic
coronary artery disease and has gained widespread acceptance. Although stent
implantation itself has been shown to reduce restenosis compared to balloon angioplasty,
in-stent restenosis still occurs in 10-40% of patients. In-stent restenosis has long
been considered the main limitation hampering the long-term efficacy of coronary stenting.
Restenosis after stent occurs secondary to the accumulation of smooth muscle cells
and extracellular matrix which consists of proteoglycans, hyaluronan and collagen.
To overcome this major limitation, drug-eluting stents were developed. Drug-eluting
stents consist of a drug (immunosuppressive, antiproliferative, or anti-inflammatory
drug), a polymer, and a stent platform. Several drugs with durable or erodable polymers
were tested in clinical trials and showed that drug-eluting stents significantly inhibit neointimal
growth compared with bare metal stents. Currently, drug-eluting stents have
been widely distributed all over the world and become main-stream of percutaneous
coronary intervention. However, (1) long-term efficacy and chronic vascular response after
drug-eluting stents implantation in humans (Part 1 of this thesis) (2) effect of drugeluting
stents for patients with high in-stent resteonsis risk factors, such as diffuse lesion,
diabetes mellitus, left main coronary artery lesion, chronic total occlusion or bifurcation
lesion (Part 2 of this thesis), have not been fully investigated. Furthermore, problem of
stent thrombosis is still observed in drug-eluting stent era. Drug-eluting stents interferes
with the natural healing response by preventing or significantly delaying the formation
of a functional endothelial lining over stent. The early establishment of a functional endothelial
layer after stent implantation may resolve this issue. Recently, the existence of
circulating endothelial progenitor cells has been identified as a key factor for re-endothelialization.
8,9 New concept stent using immobilized antibodies targeted at endothelial
progenitor cell surface antigens has been developed. (Part 3 of this thesis).