Evaluation of a tapered polymer-free sirolimus-eluting stent in porcine coronary arteries

Background: No stent is yet available for tapering coronary arteries. The purpose of the present study is to evaluate the applicability, efficacy and safety of a novel tapered, polymer-free sirolimus eluting stent (t-PFSES) specifically designed for tapering coronary arteries. Methods: 28 pigs underwent the placement of 56 oversized stents (control, n = 28, t-PFSES, n = 28), and quantitative coronary angiography (QCA) and histopathologic analysis were performed at 1, 3 and 6 months follow-up. Results: In proximal segments, both the t-PFSES and control stents lead to similar results, while, in distal segments, the t-PFSES stent was associated with significantly improved angiographic outcomes. Compared with the control stents, t-PFSES exhibited a greater inhibition of neointimal hyperplasia in all stented segments, but the magnitude of the neointimal area was lower in the proximal segments than in the distal segments, (1.15 vs. 1.48 mm2, 0.33 vs. 0.8 mm2, 0.3 vs. 1.14 mm2 at 1, 3 and 6 months, respectively, P > 0.05). Complete re-endothelialization was observed with both stents at 1 month post-procedure, but the t-PFSES stented distal segments had numerically lower inflammation scores (P = NS). Conclusion: The t-PFSES stent is applicable to coronary artery segments with marked tapering (10% tapering or 0.45 mm). Compared with the conventional bare metal stent, t-PFSES appeared to be safer and lead to superior angiographic outcomes, especially in the distal segments of tapering coronary arteries.