Prevention of restenosis in coronary arteries: ionic radiation, non-ionic radiation and drug eluting stents

Over the last decade, coronary stents have revolutionized the field of interventional cardiology. Stent implantation has become the new standard angioplasty procedure1-3. This popularity has grown because of 2 main reasons: first, the unique capability to master a major complication of balloon angioplasty - (sub) acute vessel closure - and second, a superior long-term outcome in comparison to balloon angioplasty4-8. The high reliability of the acute angioplasty result allowed for a continuos expansion of the indication for catheter-based intervention (including ostial lesions9, bifurcation lesions10, 11, left main lesions12, 13, multiple lesions14). In-stent restenosis However, in-stent restenosis remains the major limitation of coronary stenting. The absolute number of in-stent restenotic lesions is increasing in parallel with the steadily increasing number of stenting procedures and with the complexity of culprit lesions. The treatment of instent restenosis is technically challenging and costly. In subsets of lesions (such as small vessel size and diffuse disease) an anticipated high risk for restenosis may even prevent the use of stents. Restenosis represents a local vascular manifestation of the general biologic response to injury15. Injury consists of denuding the intima and stretching the media. Current concepts describe three mechanisms of the restenotic process: early elastic recoil, late vessel remodeling and neointimal growth16, 17. We could demonstrate (chapter 2) that coronary stents provide mechanical scaffolding that virtually eliminates recoil and remodeling18. However, neointimal growth continues to be a major problem. New strategies for the prevention of in-stent restenosis Over the last 2 decades, efforts for the prevention of restenosis were focused on optimizing stent characteristics and implantation technique19, 20. The growing understanding of vascular biology and the observation that exaggerated neointimal formation shows similarities to tumor growth triggered the development of new treatment strategies