Sirolimus- or paclitaxel-eluting stents to prevent coronary artery restenosis

The restenosis rate is lower with stent implantation than with balloon angioplasty. Nevertheless, even with the use of stenting, restenosis still occurs in approximately one-third of patients with diabetes, small coronary vessels, and long lesions. The two drugs commonly used in eluting stents are sirolimus and paclitaxel. Systemically administered sirolimus decreased vascular proliferation in animal models. After preliminary trials showing benefit with sirolimus-eluting stents in de novo coronary lesions, the large-scale SIRIUS (Sirolomus-coated Bx Velocity balloon-expandable stent in the treatment of patients with de novo coronary artery lesions) trial was undertaken. SIRIUS showed that sirolimus reduced restenosis and target vessel revascularisation, compared to bare stents. These benefits were also apparent in the diabetic, and small- and long vessel subgroups. The RESEARCH (Rapamycin-eluting Stent Evaluated At Rotterdam Cardiology Hospital) registry have established that sirolimus-eluting stents are superior to bare stents in practice. Thus, the benefits of sirolimus-eluting stents over bare stents have been clearly established, and sirolimus can be considered the benchmark eluting agent for the prevention of coronary artery restenosis. Animal studies with paclitaxel-eluting stents, mainly in endothelium denuded normal vessels, have shown that paclitaxel reduces restenosis in the short-term, and that this may be a delay, rather than a prevention of restenosis. In clinical trials, stents eluting the paclitaxel derivative 7-hexanolytaxol, or paclitaxel without a polymer, delay rather than prevent restenosis. Slowing the release of paclitaxel with a polymer base in the TAXUS (Taxol(trade mark) [paclitaxel]-eluting stent) series of clinical trials reduced the revascularisation rate at 12 and 18 months, indicating that polymer-based paclitaxel is effective for longer. The results of the REALITY trial comparing the sirolimus- and paclitaxel-eluting stents in diabetics and other high-risk patients are eagerly awaited.