Background: Short-term outcomes regarding the safety and efficacy of a polymer-free everolimus-eluting stent (EES) with a nitrogen-doped titanium dioxide (N-TiO) film in a swine coronary model have been reported. However, the long-term results of the use of this type of stent have not yet been evaluated or compared to those of other polymer-free coronary stents. Therefore, this study aimed to determine the mid- to long-term safety and efficacy of a polymer-free EES with an N-TiO film in a swine coronary model.Methods: Polymer-free EES with N-TiO films (n = 30) and polymer-free sirolimus-eluting stents (SES; n = 30) were implanted in 30 pigs. Quantitative coronary analysis and optical coherence tomography were conducted immediately and at 1 (quantitative coronary analysis only), 3, and 6 months after stenting. Histopathologic examinations were performed at 1, 3, and 6 months after stenting.Results: The polymer-free EES group had a lower percentage of neointimal growth than the polymer-free SES group at 3 months (22.5% +/- 11.4% vs. 32.1% +/- 12.3%; p < 0.001). The polymer-free EES group had a lower fibrin score than the polymer-free SES group at 1 month (1.9 +/- 0.45 vs. 2.5 +/- 0.54; p = 0.001). The re-endothelialization rates were similar between groups. The polymer-free EES group had a lower percentage of the area of stenosis than the polymer-free SES group throughout the follow-up period.Conclusions: The novel polymer-free EES with an N-TiO film has superior safety and efficacy than the polymer-free SES at the 6-month follow-up in a swine model.
