Self-expanding intracoronary stents in the treatment of coronary artery disease: new developments and future directions

The first stent implanted in the human coronary circulation was a self-expandable (SE) stent and was introduced almost simultaneously with the first balloon-expandable (BE) stents in the late 1980s. Nowadays, the majority of the available stents are delivered by balloon expansion. While BE stents reach their final size at the time of implantation, the SE stent continues to enlarge days to weeks after implantation. Potential advantages of the self-expandable and self-apposing properties of nitinol stents, a super-elastic metallic alloy of nickel and titanium, could be reduction of acute and late acquired stent malapposition with a subsequently decreased risk of target vessel restenosis. Several nitinol stents have been developed and clinically evaluated and are now in use in daily clinical practice. However, it is important to further improve and optimize the SE stent design and apply newer strategies to the development of next generation SE stents. The present review will provide an overview of the development of these devices and the currently available clinical evidence of the contemporary SE stents.