A novel platinum chromium everolimus-eluting stent for the treatment of coronary artery disease

Abstract

The development of coronary stents represents a major step forward in the treatment of obstructive coronary artery disease since the introduction of percutaneous coronary intervention. The initial enthusiasm for bare metal stents was, however, tempered by a significant incidence of in-stent restenosis, the manifestation of excessive neointima hyperplasia within the stented vessel segment, ultimately leading to target vessel revascularization. Later, drug-eluting stents, with controlled local release of antiproliferative agents, consistently reduced this need for repeat revascularization. In turn, the long-term safety of first-generation drug-eluting stents was brought into question with the observation of an increased incidence of late stent thrombosis, often presenting as myocardial infarction or sudden death. Since then, new drugs, polymers, and platforms for drug elution have been developed to improve stent safety and preserve efficacy. Development of a novel platinum chromium alloy with high radial strength and high radiopacity has enabled the design of a new, thin-strut, flexible, and highly trackable stent platform, while simultaneously improving stent visibility. Significant advances in polymer coating, serving as a drug carrier on the stent surface, and in antiproliferative agent technology have further improved the safety and clinical performance of newer-generation drug-eluting stents. This review will provide an overview of the novel platinum chromium everolimus-eluting stents that are currently available. The clinical data from major clinical trials with these devices will be summarized and put into perspective.

Clinical utility of platinum chromium bare-metal stents in coronary heart disease

“…Strut thickness of 81 µm, and a unique design of interconnected serpentine segments contribute to an excellent flexibility, deliverability, and conformability. 25 Improved stent behavior is further enhanced by a limited number of connectors (n=2) between segments, while connectors arranged in a kind of double helix configuration facilitate independent stent segment motion, while balancing forces in the stent ( Figure 2 ). A particular design feature of the Element platform is the nested orientation of stent segment peaks, hereby avoiding strut-to-strut contact during stent tracking in tortuous anatomies, or during deployment in a bend.…”

“…Finally, wider segment peaks and shorter segment lengths redistribute expansion strain in the longitudinal direction, hereby increasing radial strength, while simultaneously improving conformability. 23 , 25 …”

“…In contrast with most other latest generation stents, often available in two models mounted on a wider range of balloon sizes, the Element stent platform was developed in four sizes to accommodate for an optimal surface-to-artery ratio ( Figure 3 ). 23 , 25 Such tailored design reduces the risk of plaque prolapse, by allowing more uniform scaffolding and contact with the vessel wall, hereby insuring a uniform drug release. The smaller 2.25 mm model stent has even a more individualized design with shorter (and thus more) segments per stent as compared with the larger diameter models as well as a lower system profile, optimizing the conformability and deliverability in small and often more tortuous vessels.…”

“…Finally, stent performance in Element was optimized by implementation of a tailored stent delivery system, similar to the Apex balloon catheter (Boston Scientific), using a bisegment inner lumen technology to offer maximal distal shaft and balloon flexibility as well as proximal shaft pushability. 23 , 25 …”

Advances in stent technologies and their effect on clinical efficacy and safety

“…Everolimus binds to FKBP12 and interferes with a regulatory protein that controls cell metabolism and proliferation through inhibition of protein translation 52. It has a direct effect on vascular endothelium and has been shown to significantly reduce neointimal proliferation 41.…”