A New Polymer Concept for Coating of Vascular Stents Using PTFEP (poly(bis(trifluoroethoxy)phosphazene) to Reduce Thrombogenicity and Late In-Stent Stenosis

OBJECTIVES:We sought to evaluate the new polymer PTFEP (poly(bis(trifluoroethoxy)phosphazene) for (1) its ability to reduce thrombogenicity and late in-stent stenosis and (2) its effect on endothelialization in a rabbit iliac artery model. MATERIALS AND METHODS:Nanocoated (∼50 nm) and bare stainless-steel stents were implanted bilaterally in the iliac arteries of 30 New Zealand White rabbits (1, 4, 8, 12, and 16 weeks follow-up) and evaluated by angiography, light, and scanning electron microscopy. RESULTS:Bilateral stent placement was successful in 27 of 30 rabbits. Thrombus depositions occurred in none of the 27 coated but in 4 of the 27 bare stents (P = 0.037). A normal angiogram was obtained in 18 of 22 coated stents at risk for restenosis (follow-up ≥4 weeks) but only in 13 of 22 bare stents (P = 0.023). Marked restenosis (luminal loss >30%) was found in 6 bare stents (P = 0.011) but not in any coated stents. The neointima was 47.7–73.9 μm on coated and 66.9–115.2 μm on bare stents (statistically significant at 4, 8, and 16 weeks). Scanning electron microscopy detected full endothelialization in all stents from 4 weeks on (22 stents in both groups). CONCLUSION:PTFEP nanocoating successfully showed thromboresistance and reduced late in-stent stenosis. Endothelialization was equal in both stent types. Studies in more human-like models and human feasibility studies in human arteries are encouraged.