Importance of knowing stent design threshold diameters and post-dilatation capacities to optimise stent selection and prevent stent overexpansion/incomplete apposition during PCI

Autor: Ricardo Petraco, Darrel P. Francis, S Nijjer, Sayan Sen, Justin E. Davies, C. Di Mario, Eduardo Alegría, N. Foin
Rok vydání: 2013
Předmět:
Zdroj: International Journal of Cardiology. 166:755-758
ISSN: 0167-5273
DOI: 10.1016/j.ijcard.2012.09.170
Popis: Coronary stents are generally produced in only 2 or 3 different model designs that fit all the different diameters available. As a result, one stent model covers a range of diameters with only the delivery balloon diameter changing between the different sizes. Information about the cut-off diameter between the different workhorse designs is not commonly provided by manufacturers. This can however be critical as it determines the relative stent-toartery ratio, stent expansion behaviour and maximal achievable diameter. In this letter, we present the difference in stentworkhorse design for 6 widely used drug eluting stents (DES). We tested previously the overexpansion capacity of each stent design with post-dilatation using a balloon diameter of up to 6 mm [1]. We show here examples of how, in the absence of this critically important information, stents implanted in segments with major changes in vessel diameter have the potential to become grossly overstretched and to remain incompletely apposed. We examined the differences in designs of 6 commercially available drug eluting stents (DES): the Paclitaxel eluting stainless steel Taxus Liberte (Boston Scientific, Natick, MA), Everolimus coated PtCr Promus Element (Boston Scientific, Natick, MA) and CoCr Xience Prime (Abbott Vascular, Santa Clara, CA), the Zotarolimus eluting CoCr Resolute Integrity (Medtronic, Santa Rosa, CA), the Biolimus eluting stainless steel BioMatrix Flex (Biosensors International, Morges, Switzerland) and the Sirolimus eluting stainless steel Cypher Select stent (Cordis, Warren, NJ). The Table 1 indicates the different model designs at different sizes for the 6 DES studied. We deployed samples of all the different stent workhorse designs in-vitro at nominal pressure and tested overexpansion capabilities of each design with successive post-dilatations using a 4.0×12 and 5.0×12 non-compliant balloons (NC Quantum Apex, Boston Scientific, Natick, MA) inflated at 14 ATM; and for the largest designs (4 mm size), we used a 6.0×15 mm semi-compliant balloon (Maverick XL, Boston Scientific, Natick, MA) with a pressure of 14 ATM. Post-dilatation was performed on the proximal segment of the stent, corresponding to an approximate stent length of 15 mm. Final dilatationwas repeated twice to ensure anoptimal expansionof the stent struts. Minimal inner lumen diameter (excluding struts) on the overexpanded stents was evaluated using high resolution micro-CT (HMX 225, X-TEX, Tring, UK). The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology. Results are displayed in Table 1. The achieved inner stent MLD, after overexpansion of the stents using post-dilatation balloon sizes up to 6 mm, is tabulated. [For complete protocol and analysis, see [1]]. Four stent platforms investigated: Xience Prime, Resolute Integrity, BioMatrix Flex and Cypher Select stent have only 2 designs to cover the entire range of diameters. Cut-off diameter for stents with 2 designs is generally between 3.0 mm and 3.5 mm, except for the Resolute Integrity for which the designs change at 2.75 mm. The Taxus Liberte stent platform is provided with 3 model designs with cut-offs at 2.5 mm and 3.5 mm. The Promus Element platform has the largest number of designs with 4 different models: a very small vessel model for the 2.25 mm diameter, a small vessel workhorse for 2.5 and 2.75 mm stent size, a mid-size workhorse for 3.0 mm and 3.5 mm diameters and a large vessel design at 4.0 mm. Despite important structural deformation observed with all platforms, all designs tested could be overexpanded largely above their labelled maximal diameter, achieving an MLD of at least 5.4 mm with the largest designs. Stents made with only 2 designs showed a comparable expansion range to stent platforms made with 3 or 4 different designs. Interestingly, a “closed cell” design did not seem a major limiting factor: in this in-vitro study, the Cypher stent showed a large expansion capacity, comparable to “open-cell” stent designs. This paper shows that
Databáze: OpenAIRE
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