Metallic surface treatment using electrochemical polishing decreases thrombogenicity and neointimal hyperplasia of coronary stents

An abundant healing response resulting in a more pronounced neointimal hyperplasia compared to conventional balloon angioplasty remains the most important clinical problem after coronary stent implantation. In the present study the potential beneficial effect of metal surface treatment using electrochemical polishing on stent thrombogenicity and neointimal hyperplasia was evaluated in a rat A-V model and a porcine coronary model. An electrochemical polishing system was developed to improve surface characteristics of stainless steel stents. Topographic scanning of the stent surface using a profilometer type Taylor Holson Form Taylsurf 120L showed a significant effect on Ra (arithmetic mean of the roughness height) (0.14 vs 0.04 μm: P < 0.001) and Rt (maximum rouhgness height between a peak and a valley for the sampling length) (1.44 vs 0.43 μm: P < 0.001). Thrombogenicity of polished stents (n = 6) was compared to nonpolished stents (n = 5) in a rat A-V shunt model using ¹²⁵I fibrinogen and ⁵¹Cr-labeled platelets. Total clot weight after 30 minutes was significantly lower in the polished stents (32.1 + 2.8 vs 18.1 + 4.4: P < 0.001). Also ¹²⁵I fibrinogen deposition was significantly lower in the polished stents (1.30 + 0.07 vs 0.66 + 0.04: P < 0.001). Platelet deposition, however, was not significantly reduced (12.7 + 3.4 vs 9.87 + 1.9, NS). Subsequently, the effect of electrochemical polishing on neointimal hyperplasia was evaluated in a porcine coronary model. Polished (n = 10) and nonpolished stents (n = 10) were randomly implanted in the right coronary artery of healthy pigs. Neointimal hyperplasia was significantly decreased in the polished stents (0.6 + 0.28 vs 0.9 + 0.34 mm²: P