A review of current devices and a look at new technology: drug-eluting stents

Drug-eluting stents (DES) have become the standard of care for the treatment of coronary artery disease. However, late stent thrombosis has emerged as a major concern, especially in 'off-label' use. Pathologic studies of patients dying from late DES thrombosis demonstrate delayed arterial healing, characterized by persistent fibrin deposition and poor endothelialization as the primary substrate. Therefore, next-generation DES are being developed to increase the safety and biocompatibility by optimizing the three major components of DES: the stent platform, the polymer and the drug. Stents with thinner struts are endothelialized rapidly and cause less vessel-wall injury. Non-erodable polymers applied thinly and without defect or cracking cause less inflammation and will result in better long-term safety. Furthermore, use of biodegradable polymers, which fully degrade and leave a bare metal stent, will result in less inflammation. The choice of drug, dose and release kinetics should also be optimized. In addition to the improvement of DES components, new approaches, such as polymer-free drug delivery, prohealing approach and fully biodegradable stents, are emerging. Importantly, these technologies focus not only on efficacy but also on safety. The next-generation DES will probably be safer, with goals of improving endothelialization and more rapid arterial healing compared with first- and second-generation DES.