Bioresorbable Scaffold Technologies

Abstract

Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp he application of bioresorbable devices has previously been tested in multiple medical fields, such as stenting of pediatric pulmonary artery stenosis, 1 management of recurrent benign strictures of the esophagus, 2 treatment of coronary artery stenosis 3-6 and peripheral artery disease (Igaki-Tamai stent, see later). Within the field of interventional cardiology, percutaneous coronary intervention (PCI) with fully bioresorbable scaffold (BRS) devices have recently attracted great interest. Since BRS devices aim to provide temporary mechanical support to the vessel wall and subsequently disappear, the technology has the potential to overcome many of the safety concerns associated with metallic drug-eluting stents (DES), and possibly even convey further clinical benefit. Although the technology is still in its infancy, several devices have been tested in clinical trials and the initial results have been very promising.This review will discuss the emerging need for BRS, the theoretical advantages of this new technology over current generation metallic DES and review the status of the currently available BRS. In addition, we will discuss the ideal duration of bioresorption, the proven and potential clinical benefits, and future perspective of this rapidly progressing technology. The Emerging Need for Fully Bioresorbable Scaffold:Historical PerspectiveInvention of balloon angioplasty in 1977 by Andreas Gruntzig was a huge leap forward in the treatment of obstructive coronary artery disease, and was undoubtedly the 1st revolution in interventional cardiology. However, the mode of treatment was limited by risks of acute occlusion in the treated vessel as well as frequent restenosis, which occurred in approximately 30% to 40% of lesions after angioplasty. 20 However, this early enthusiasm with metallic DES has been tempered in recent years by widespread concerns regarding the safety of DES with respect to acute, late and very late stent thrombosis. Registries of all-comers treated with DES demonstrated rates of late stent thrombosis of 0.53% per year, with a continued increase to 3% over 4 years. 21, 22 In patients with complex multivessel disease, the rate of combined definite, probable and possible stent thrombosis was as high as 9.4% at 5 years Fully bioabsorbable scaffolds (BRS) are a novel approach that provides transient vessel support with drug delivery capability without the long-term limitations of the metallic drug-eluting stents (DES), such as permanent caging with or without malapposition. The technology has the potential to overcome many of the safety concerns associated with metallic DES, and possibly even convey further clinical benefit. Although the technology is still in its infancy, several devices have been tested in clinical trials and the initial results have been very promising. This review will discuss the emerging need for BRS, the theoretical advantages of this new technology over current generati...

Metallic zinc exhibits optimal biocompatibility for bioabsorbable endovascular stents

“…The reduced radial strength and ductility of polymeric stents have necessitated substantially larger struts and, in some models, the introduction of a “locking” mechanism to maintain luminal cross sectional area following deployment. This larger profile of the polymer stents necessitate a larger introducer sheath and catheter for delivery relative to metal stents, which can result in an increased risk of vascular injury and blood flow disruptions [27]. This may preclude their use in younger infant and pediatric populations [13].…”

Reduction in the Corrosion Rate of Magnesium and Magnesium Alloy Specimens and Implications for Plain Fully Bioresorbable Coronary Artery Stents: A Review

“…The former type of stent 1) may be monitored with a non-invasive technique, such as advanced multi-slice computed tomography or magnetic resonance imaging, without causing any metallic artifacts; 2) might restore late expansive remodeling, favorable vascular dynamics, adaptive shear stress, and late lumen enlargement, each of which may contribute to decreased rates of neo-atherosclerosis, in-segment restenosis (ISR), and in-stent thrombosis (ST); 3) has low possibility for strut fracture; and 4) obviates the need for prolonged DAPT, thus minimizing the risk for bleeding in high-risk patients such as elderly ones and those on oralanti-coagulants [39] [40] [41] [42] [43]. Furthermore, after resorption of a bioresorbable stent, 1) there will be full restoration of vascular architecture, endothelium function within the stented area of the artery segment, vasomotion, distensibility, pulsatility, and mechano-transduction; 2) a thick circumferential fibrous layer similar to a thick fibrous cap will be left behind, which may facilitate reduction of the plaque burden; and 3) there will be the option for repeat revascularization (via CABG or PTCI) in or outside the area of original stenting, an option that is particularly important in certain cases, such as those involving bifurcating lesion(s) [47] [48].…”

Progress in interventional cardiology: challenges for the future

“…A magnesium-based degradable stent was absorbed too quickly in clinical trials (52). Today, the most promising material for biodegradable stents still is chemically modified poly-lactic acid (57); although the first clinical trial with the so-called bioresorbable vascular scaffold (BVS) stent had to be aborted because of an elevated late lumen loss that has been attributed to some inflammatory reactions and the mechanical properties of the stent (58), after an adaptation of the stent geometry, the second BVS generation yielded improved clinical results in a recent pilot trial (54,59) and, having been CE (Conformité Européene) approved in Europe in 2011, has nowadays gained considerable clinical relevance. However, the experience for the use of BVS in bifurcation lesions as well as across major side branches or calcified vessels is still limited (60,61).…”