biodegradable polymer, coronary artery disease, Everolimus, ultra-thin strut
Significant development has been made in the field of percutaneous coronary intervention (PCI) from bare metal stents (BMS) to drugeluting stents (DES). The implantation of BMS was utilized as a minimally persistent treatment for disruptive CAD patients. After the implantation of BMS, few challenges occurred during 6-12 months follow-up, among which stent restenosis or re-narrowing of the treated artery was common in one-third of the patients . It can be resolved using first generation DES with antiproliferative drug. Henceforth, development in stent platform, polymer coating, and drug have revolutionized the approach to treat CAD . Limitation of the first-generation DES is the growing concern for very late stent thrombosis. As a result, second-generation DES with biodegradable polymer coated stent platform was developed from stainless steel to cobalt-chromium (Co-Cr) or platinum-chromium (Pt-Cr) . Thus, the second- generation DES which release everolimus or zotarolimus were associated with lower ST rates. At present, everolimus-eluting stents (EES) are the most frequently used DES.
In the advancement of technology of the DES, the Evermine 50™ (Meril Life Sciences, India) EES with biocompatible and biodegradable polymer poly-L-lactic acid (PLLA) and poly-lactic-co-glycolic acids (PLGA) base has been developed. Evermine 50 is a novel Co-Cr L605 platform with a “hybrid” cell design coronary DES system. It incorporates an advanced ultrathin stent platform with ultralow strut thickness 50 μm coated with a biodegradable polymer and which releases everolimus (1.25 μg/mm2) as an antiproliferative drug. Evermine 50 EES also approved by DCGI and CE.
EES reported a lower rate of cardiac death, myocardial infarction (MI), target lesion revascularization (TLR), and reported a lower risk of stent thrombosis (ST), in recent studies after the implantation of EES with cobalt-chromium platform compared with BMS [4,5]. The Evermine 50 EES is a rapid-exchange delivery percutaneous transluminal coronary angioplasty balloon catheter. The stent is premounted on a balloon catheter and placed between two platinumiridium radio-opaque markers bands.
Why is second-generation DES Evermine 50 more effective than their older counterparts? They differ from the first-generation stent with respect to the ultra-low strut thickness of stent, the polymer layer, and the stent frame. The strut thickness of Evermine 50 is 50 μm. It is the first ultra-lowest as compare to others Cypher (140 μm), TAXUS Express (132 μm), TAXUS Liberte (96 μm), Resolute Onyx (81 μm), Xience (81 μm), Xience Xpedition (81 μm) and SYNERGY (74 μm) [6-8]. The Evermine 50 EES-KLES ongoing study with 171 patients of Evermine 50 result shows 2.08% rate of MACE, and no any stent thrombosis reported at 12 months follow-up period. It is registered at Clinical Trials Registry-India (CTRI) with Number: CTRI/2017/09/009939.
The problems arising due to the durable polymer with thicker metallic stents was resolved using thin strut biodegradable polymer coated stents with PLLA and/or PLGA . Therefore, many researchers have recently focused their attention on the development of ultrathin biodegradable polymer coated DES. Lower strut thickness might have potential advantages in terms of flow disturbance.
EES are the most frequently used DESs. The EES was established as non-inferior to sirolimus-eluting stents (SES) in the DESSOLVE III and EXCELLENT trials and superior to paclitaxel-eluting stents in metaanalysis SPIRIT clinical trials [10-12]. Although, DES has significantly reduced the angiographic restenosis rate and has improved clinical outcomes, late lumen loss remains an important subject of ongoing research. At present, in the search for improving the performance of available DES, various developments and clinical studies are ongoing.
The success of the present DES has shifted the focus to further development toward enhancing long-term safety and efficacy of these devices. The new generation DES will probably further improve endothelization and rapid arterial healing and will also provide better safety and performance in CAD patients.
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