Abstract:Coronary artery disease is the leading cause of death worldwide. Conventional balloon angioplasty is associated with high rates of complications such as coronary dissection and vessel recoil. The deployment of bare-metal stents (BMSs) can overcome these problems and achieve a better patency rate than simple balloon angioplasty. It has been shown that the stent design including structure platform, size, length, and strut thickness has a major influence on the clinical results. Even though angioplasty with BMS implantation is widely used in coronary interventions, the restenosis rate due to neointimal hyperplasia remains high. Therefore, drug-eluting stents (DESs) coated with anti-proliferative agents and polymers have been developed to reduce the restenosis rate and improve the clinical outcomes. Although the repeat revascularization rate of DESs is lower than that of BMSs, the long-term stent thrombosis rate is higher than for BMSs. Therefore, new and emerging generations of stents, in which, for example, thinner struts and bioresorbable polymers are used, are available for clinical use. However, there are only a limited number of clinical trials, in which these newer stents have been compared with BMSs and first-and second-generation DESs. The purpose of this review was to provide up-to-date information on the evolution of coronary artery stents from BMSs to DESs to bioresorbable stents (BRSs).Keywords: coronary artery disease; stent; bioresorbable; drug; polymer; strut
The Evolution of Coronary Stent DevelopmentCoronary artery disease (CAD) is a major cause of mortality and morbidity. One of the treatment options for CAD is a percutaneous coronary intervention. Balloon angioplasty alone, which involves pushing the plaque to the walls of the artery, can achieve a larger luminal diameter in the acute phase. However, arterial recoil, dissection, and late neointimal hyperplasia can result in vessel restenosis. Therefore, bare metal stents (BMSs) made from metallic materials were developed to overcome the dissection and the restenosis complications caused by recoil. Although the restenosis rate can be reduced by stenting, the in-stent restenosis (ISR) rate is still high at around 20%-30% [1,2]. ISR is mostly caused by neointimal hyperplasia.A reduction in restenosis was first achieved with the evolution of the stent platform, including thinner stent struts and new metal compounds. Furthermore, new drug delivery systems and polymer coatings have been developed to achieve better clinical outcomes. The first generation of drug-eluting stents (DESs) with a sirolimus or paclitaxel coating showed better clinical outcomes with lower rates of cardiac death, myocardial infarction, and target vessel revascularization than BMSs [3,4]. However, increased rates of stent thrombosis were reported with first-generation