Second- and third-generation drug-eluting coronary stents: progress and safety

Drug-eluting stents (DES) have revolutionized the treatment of coronary artery disease by reducing the rate of in-stent restenosis from 20-40% with bare-metal stent (BMS) to 6-8% with DES. However, with widespread use of DES, safety concerns have risen due to the observation of late stent thrombosis. With this in mind and better understanding of mechanism and pathophysiology of stent thrombosis, the technological platform, especially innovative anti-restenotic agents, polymeric coatings, and stent platforms, improved with newer DES. Two second-generation DES, the Endeavor zotarolimus-eluting stent (ZES) and the Xience-V everolimus-eluting stent (EES), have provided promising results in both randomized controlled trials (SPIRIT and ENDEAVOR) and registries (E-Five, COMPARE) compared with bare-metal stents (BMS) and first-generation DES. Newer third-generation stent technology, especially biodegradable polymers, polymer-free stents, and biodegradable stents on the basis of poly-L-lactide (PLLA) or magnesium, has been evaluated in preclinical and initial clinical trials. However, despite encouraging initial results, long-term data of large-scale randomized trials as well as registries comparing them to currently approved first- and second-generation DES are still lacking.