Abstract 2553: Novel Cobalt-Chromium Ultra-Thin Strut Stent: Feasibility, Vascular Compatibility, and Safety Evaluation in Porcine Coronary Arteries

Abstract

Stent-strut thickness is related to in-stent restenosis. Therefore, modern bare-metal stents (BMS) with lower strut thickness are in development. We sought to evaluate a new ‘third-generation’ BMS comprising an ultra-thin-strut, cobalt-chromium platform with fixed geometry and uniform cell sizes, in a clinically relevant animal model. 36 BMS of two types were implanted in pig coronaries using quantitative coronary angiography (QCA) to optimize stent apposition: a commercially available cobalt alloy thin-strut stent (91μm) as control (n=18), and an ultra-thin-strut (65μm) cobalt-chromium stent (Protea CoCr; n=18). Animals underwent angiographic restudy and termination 1-wk and 1-mo post-implant for coronary artery histology. In addition, 12 overlapping Protea CoCr stents were analyzed at 1-mo. All stents deployed without difficulties. Thin neointima and mild inflammation was seen in both groups at 1-wk. For 1-mo, QCA % diameter stenosis was significantly less for Protea CoCr (2±5% vs. 17±16%, p=0.032). By histomorphometry, intima thickness (0.11±0.05mm vs. 0.23±0.11mm, p=0.003) and % area stenosis (19±1% vs. 32±11%, respectively, p=0.004) were also significantly lower for Protea CoCr. The strut injury score was low and similar between the two groups. QCA % stenosis; intima thickness; and % area stenosis of overlapping Protea CoCr were 3±3%, 0.13±0.02mm, and 22±4%, respectively. Stable fibrocellular neointimal incorporation of all stents including overlapped Protea CoCr, with complete endothelialization and minimal inflammation, was seen at one month. Protea CoCr showed favorable arterial response with significant reduction of neointima formation compared to a commercial cobalt alloy BMS, one month post implant in pig coronary arteries. This ultra-thin-strut stent platform therefore appears to be a suitable and attractive alternative to current BMS. Combining the lower levels of neointima formation, fixed geometry, and uniform cell size, the Protea CoCr may be a preferred platform for next-generation drug-eluting stents.