Occlusive coronary artery disease is predominantly caused by coronary atherosclerosis, a pathologic vascular condition characterized by abnormal lipid and fibrous tissue accumulation in the vessel wall. This condition may be accompanied by degenerative changes and/or calcification leading to stenosis (narrowing) of the luminal channel. Percutaneous Transluminal Coronary Angioplasty (PTCA) is a well-accepted method of non-surgical myocardial revascularization for selected patients with symptomatic occlusive coronary artery disease.
Restenosis is the most important challenge limiting the long-term success of coronary angioplasty. Symptomatic restenosis usually occurs 6 months after an angioplasty procedure. The rates of restenosis reported in numerous clinical trials vary from 13% to 57%. This variability may be attributed in part to differences in the methods used to assess the occurrence of restenosis and in the criteria used to define restenosis. Regardless of the exact percentage, restenosis remains the Achilles heel of angioplasty. Numerous pharmaceutical approaches to limit restenosis have been tested, but none have been successful to date.
It was chosen to coat the stent with Titanium Nitrate (TiN), which is an inert, biocompatible material, that creates a thin physical barrier to diffusion of toxic metal atoms, TiN creates a very smooth surface that is impossible to obtain with a metal alloy. This coating was applied to the cobalt chromium platform, "Numen", made of the L605 Cobalt-20 Chromium-15 Tungsten-10 Nickel alloy. This alloy contains the lowest Nickel percentage of Cobalt Chromium alloys used for surgical implants. The strut thickness of the platform is reduced to the minimum of 65 microns for optimal hemodynamic performance and to permit an ultra low profile delivery system. The "Numen" design complies with the requirements of the "LMS -Less Mismatch Stent" theory applied where multiple 1 mm high zigzags form the stent pattern to align the segments at 45° with respect to blood flow when the stent is expanded to its nominal diameter. TiN coating is being used commercially for their hard-wearing and chemical inactive properties, particularly for surgical tools. TiN features chemical stability, great hardness, excellent wear properties, low electric impedance, biocompatibility, hemocompatibility and the possibility, through the application process, to exchange the orientation of the grains, the hardness, the wear characteristics and also the biocompatibility (a nanocrystalline structure produces a chemical surface more suitable for the endothelial cells). The produced coatings were very fine grained and dense with a porosity within the film structure of less than 10 nm in diameter. Furthermore, in an iliac artery stent model in normal rabbits, safety and efficacy in reduced restenosis of the TiN coated Numen™ stent was assessed.
The special TiN coating of the Mar-Tyn stents is very promising in reducing the lesions and the causes of intima neoplasia.
This study is a multicenter (up to 8 European centers), prospective, randomized single blind study. This study has a 2-arm design assessing the safety and effectiveness of the Tin-coated MAR-Tyn stent to an uncoated control cobalt-chromium balloon-expandable stent (Vision, Abbott Vascular), both mounted on a Rapid Exchange Stent Delivery System. A total of 160 patients will be entered in the study and will be randomized on a 1:1 basis. Patients who meet the eligibility criteria will be either randomized to Treatment A or Treatment B. The patient will not know which stent will be implanted while the physician will be unblinded . Patients will be followed at 30 days, 6, and 12 months post-procedure, with all patients undergoing repeat angiography at 6 months. All adverse events up to the 1 year follow-up period will be collected and analyzed.
