Sirolimus-eluting vs Zotarolimus-eluting Stents for Chronic Total Coronary Occlusions

Overview

Primary intracoronary stent placement after successfully crossing chronic total coronary occlusions (CTO) decreases the high restenosis rate at long-term follow-up compared with conventional balloon angioplasty. Several studies have shown the efficacy of sirolimus-eluting stents in selected groups of patients. In the PRISON II study we demonstrated that sirolimus-eluting stents were superior to bare metal stents in CTO. In this prospective randomized trial, sirolimus-stent implantation will be compared with zotarolimus-eluting stent implantation for the treatment of chronic total coronary occlusions. A total of 300 patients will be clinically followed up for 1, 6, 12 months, 2, 3, 4, 5 year with angiographic follow-up at 8 months. Quantitative coronary analysis will be performed by an independent core laboratory. The primary end point is in-segment late luminal loss at 8 month angiographic follow-up.

Percutaneous coronary intervention (PCI) of chronic total occlusions (CTO) was traditionally limited by high restenosis rates. Coronary stenting using bare metal stents significantly decreases restenosis in CTO compared to balloon angioplasty alone, but restenosis rates still reach 32-55%. In 200 patients with CTO, randomized in the PRISON I study we demonstrated a restenosis rate of 22% after bare metal stent (BMS) implantation as compared with 33% after conventional balloon angioplasty. During the past few years, sirolimus (rapamycin), a cytostatic macrocyclic lactone with anti-inflammatory and antiproliferative properties, delivered from a polymer-encapsulated stent was shown to almost eliminate the risk of restenosis in selected groups of patients. The drug zotarolimus (ABT-578), a sirolimus analogue, is designed to inhibit the cellular process that leads to restenosis. In the PRISON II study we have randomized 200 patients with CTO to either BMS implantation or sirolimus-eluting stent implantation and we demonstrated a reduction of in-stent binary restenosis from 36% to 7% and in-segment binary restenosis rates from 41% to 11% in favour of the sirolimus eluting stent. However, no data are available on direct comparison of the clinical efficacy, safety, and angiographic outcome of particular drug-eluting stents in patients with CTO and there may be differences between various drug-eluting stents. The PRISON III study is designed to address this issue and provide information about two different drug-eluting stents. It is a prospective randomized, single blinded trial comparing the relative safety, clinical efficacy and angiographic outcomes of sirolimus and zotarolimus-eluting stents in patients undergoing successful recanalization of CTO.