Contemporary drug-eluting stents and companion polymers: durable is not synonymous with harm

On September 3, 2006 during the annual European Society of Cardiology meeting in Barcelona, two independent meta-analyses revealed for the first time that the superior efficacy of early-generation drug-eluting stents (DESs) as compared with bare metal stents (BMSs) came at the expense of increased mortality due to very late stent thrombosis (ST) (1). Subsequently, the main DESs components (supportive backbones, polymer coatings or carriers and antiproliferative drugs) underwent a systematic investigation to rule-out the underlying reasons of early-generation DESs failure. Preclinical and necropsy studies showed that, among other factors, the methacrylate-based polymers, responsible for drug-release modulation in a large part of early-generation DESs, persisted in the implanted vessel wall long after their function was duly served (2). This kind of durable carriers caused chronic inflammatory response and delayed arterial healing at the stented site, which have been associated with neoatherosclerosis, restenosis and ST over the long term (3).