[Coronary stents: 30 years of medical progress]

Determination of the Entire Stent Surface Area by a New Analytical Method

Stenting is a widely used treatment procedure for coronary artery disease around the world. Stents have a complex geometry, which makes the characterization of their corrosion difficult due to the absence of a mathematical model to calculate the entire stent surface area (ESSA). Therefore, corrosion experiments with stents are mostly based on qualitative analysis. Additionally, the quantitative analysis of corrosion is conducted with simpler samples made of stent material instead of stents, in most cases. At present, several methods are available to calculate the stent outer surface area (SOSA), whereas no model exists for the calculation of the ESSA. This paper presents a novel mathematical model for the calculation of the ESSA using the SOSA as one of the main parameters. The ESSA of seven magnesium alloy stents (MeKo Laser Material Processing GmbH, Sarstedt, Germany) were calculated using the developed model. The calculated SOSA and ESSA for all stents are 33.34%(±0.26%) and 111.86 mm (±0.85 mm), respectively. The model is validated by micro-computed tomography (micro-CT), with a difference of 12.34% (±0.46%). The value of corrosion rates calculated using the ESSA computed with the developed model will be 12.34% (±0.46%) less than that of using ESSA obtained by micro-CT.

Percutaneous coronary intervention with second-generation drug-eluting stent versus bare-metal stent: Systematic review and cost-benefit analysis

Background

Drug-eluting stents (DESs) were considered as ground-breaking technology promising to eradicate restenosis and the necessity to perform multiple revascularization procedures subsequent to percutaneous coronary intervention. Soon after DESs were released on the market, however, there were reports of a potential increase in mortality and of early or late thrombosis. In addition, DESs are far more expensive than bare-metal stents (BMSs), which has led to their limited use in many countries. The technology has improved over the last few years with the second generation of DESs (DES-2). Moreover, costs have come down and an improved safety profile with decreased thrombosis has been reported.

Objective

Perform a cost–benefit analysis of DES-2s versus BMSs in the context of a publicly funded university hospital in Quebec, Canada.

Methods

A systematic review of meta-analyses was conducted between 2012 and 2016 to extract data on clinical effectiveness. The clinical outcome of interest for the cost–benefit analysis was target-vessel revascularization (TVR). Cost units are those used in the Quebec health-care system. The cost–benefit analysis was based on a 2-year perspective. Deterministic and stochastic models (discrete-event simulation) were used, and various risk factors of reintervention were considered.

Results

DES-2s are much more effective than BMSs with respect to TVR rate ratio (i.e., 0.29 to 0.62 in more recent meta-analyses). DES-2s seem to cause fewer deaths and in-stent thrombosis than BMSs, but results are rarely significant, with the exception of the cobalt–chromium everolimus DES. The rate ratio of myocardial infraction is systematically in favor of DES-2s and very often significant. Despite the higher cost of DES-2s, fewer reinterventions can lead to huge savings (i.e., -$479 to -$769 per patient). Moreover, the higher a patient’s risk of reintervention, the higher the savings associated with the use of DES-2s.

Conclusion

Despite the higher purchase cost of DES-2s compared to BMSs, generalizing their use, in particular for patients at high risk of reintervention, should enable significant savings.