Contemporary Reviews in Interventional Cardiology Bioabsorbable Coronary Stents

Percutaneous coronary intervention (PCI) with bioabsorbable stents has created interest because the need for mechanical support for the healing artery is temporary, and beyond the first few months there are potential disadvantages of a permanent metallic prosthesis. Stents improve immediate outcomes, including profoundly reducing acute vessel occlusion after PCI by scaffolding intimal tissue flaps that have separated from deeper layers and by optimizing vessel caliber. They limit restenosis by preventing negative remodeling.1 The intimal hyperplastic healing response to PCI that contributes to restenosis, especially after bare metal stenting, can be limited by coating stents with antiproliferative medications.2,3 Potential advantages of having the stent disappear from the treated site include reduced or abolished late stent thrombosis, improved lesion imaging with computed tomography or magnetic resonance, facilitation of repeat treatments (surgical or percutaneous) to the same site, restoration of vasomotion, and freedom from side-branch obstruction by struts and from strut fracture-induced restenosis. Bioabsorbable stents have a potential pediatric role because they allow vessel growth and do not need eventual surgical removal.2 The progression of stenosis seen within stents 7 to 10 years after stenting has been attributed, at least in part, to inflammation around metallic struts, which might argue for an absorbable stent.3 Progression is also observed late after balloon angioplasty.4 Some patients say they prefer an effective temporary implant rather than a permanent prosthesis. Although the concept of bioabsorbable stents has created interest for 20 years, there are challenges in making a stent that has sufficient radial strength for an appropriate duration, that does not have unduly thick struts, that can be a drug delivery vehicle, and where degradation does not generate an unacceptable inflammatory response.5,6 We will review the different bioabsorbable stents that have been studied clinically and discuss the duration of the need for mechanical support and the potential amelioration of late stent thrombosis risk.