Objectives: The aim of this study was to evaluate the effect of variable dose and release kinetics of paclitaxel on neointimal hyperplasia.
Background: Conventional paclitaxel-eluting stents use a durable polymer coating as a vehicle for drug delivery. The Conor stent (Conor Medsystems, Menlo Park, California) with intra-strut wells and erodable polymer is specifically designed for drug delivery with programmable pharmacokinetics.
Methods: Two hundred and forty-four patients with single vessel disease received either a bare metal Conor stent (n = 53) or one of six different release formulations that varied in dose (10 or 30 microg) and elution release kinetics (first order, zero order), direction (abluminal, luminal), and duration (5, 10, and 30 days). End points at six months (bare stent group) and at four months (eluting stent groups) were angiographic late loss and neointimal tissue volume by intravascular ultrasound and the rate of major adverse cardiac events (MACE).
Results: The lowest in-stent late loss (0.38 mm, p <0.01, and 0.30 mm, p <0.01) and volume obstruction (8%, p <0.01, and 5%, p <0.01) were observed with the 10-microg and 30-microg doses in the 30-day release groups respectively, whereas the highest in-stent late loss (0.88 mm), volume obstruction (26%), and restenosis rate (11.6%) were observed in the bare stent group. The overall MACE rate of the eluting stent group was 8.6%: death 0.5%, myocardial infarction 2.7%, and target lesion revascularization (TLR) 5.3%. Sub-acute thrombosis was 0.5%. The TLR rates in the two 30-day release groups were 0% and 3.4%.
Conclusions: This novel eluting stent platform, using an erodable polymer with complete elution of low doses of paclitaxel, is safe. The inhibition of the in-stent neointimal hyperplasia was best in the long release groups.