Sirolimus-Eluting Stents versus the Superficial Femoral Artery: Second Round

Abstract

RESTENOSIS remains a major limitation of femoropopliteal interventions, despite technologic advances in numerous endovascular strategies. Percutaneous transluminal angioplasty has been only modestly successful in the treatment of atherosclerotic disease of the superficial femoral artery (SFA), with 1-year patency rates of 41%–85% depending on lesion length, presence of diabetes, and distal runoff (1–6). Vascular stents are effective in rescuing suboptimal angioplasty results. However, the impact of femoropopliteal stent placement is still compromised by neointimal hyperplasia, and multiple studies have shown no improvement in lasting patency after primary stent placement compared with angioplasty alone (1,7–9). Newer generations of nitinol self-expanding stents appear to have a positive impact on femoropopliteal patency, but this has not been confirmed in a randomized setting (10–12). Drug-eluting stents have revolutionized the treatment of coronary artery disease. In the first human application of this breakthrough technology, minimal in-stent angiographic restenosis was observed in 28 patients 2 years after implantation of sirolimus-eluting stents in coronary arteries (13). These results were confirmed in a randomized study that included 238 patients (14). At 6-month angiographic follow-up, none of the patients had in-stent restenosis in the sirolimus-eluting stent group, compared with 26.6% in the bare stent group. With use of the same technology, inhibition of in-stent restenosis was also reproduced in a study that included 850 patients with complex coronary lesions consisting of a high percentage of diabetic patients and patients with longer lesions (15). At 8-month angiographic follow-up, the in-stent restenosis rates were 3.2% versus 35.4% in the sirolimus and bare stent groups, respectively. It was hypothesized that these impressive results could be obtained in the femoropopliteal segment by applying the same technology. The first human evaluation of drugeluting stents for the treatment of obstructive SFA disease (average length of 85 mm 57) included 36 patients randomized to receive treatment with bare versus sirolimus-eluting S.M.A.R.T. stents (Cordis, Warren, NJ) (16). The 6-month angiographic follow-up revealed a larger in-stent mean lumen diameter of 4.95 mm in the sirolimus group, versus 4.31 mm in the bare stent group (P .05). The lower 6-month binary restenosis rate (0 vs 23.5%) and the lower mean in-stent percent diameter stenosis (22.6% vs 30.9%) observed in the sirolimus-eluting stent group were not significant as a result of the small sample size. It was later learned that a subgroup of five patients who had received a slow-release drug coating within the sirolimus-eluting stent group had less restenosis than patients in the fast-eluting sirolimus and bare stent groups at 9 and 18-month duplex follow-ups. The SIROCCO I study showed the feasibility and safety of the use of a drugeluting self-expandable stent platform, but it also suggested that slow-eluting stents could reduce SFA restenosis. Based on these results, the SIROCCO II extension trial, presented in this issue of JVIR, was conducted in 57 additional patients randomized to receive treatment with the slow-release form of sirolimus-eluting and bare S.M.A.R.T. stents (17). Because stent fractures were detected in six patients who had received at least three overlapping stents in the SIROCCO I study (16), a maximum of two stents per patient was allowed in the SIROCCO II study (17) to treat lesions with an average length of 81.5 mm 41.2. Although there was a trend toward better performance of sirolimus-eluting stents, the 6-month angiographic follow-up revealed no significant difference between treatment groups in any of the variables: the in-stent mean lumen diameter values were 4.94 mm 0.69 versus 4.76 mm 0.54, the binary restenosis rates were zero versus 7.7%, and the late loss values were 0.038 0.64 versus 0.68 0.97 in the sirolimus and bare stent groups, respectively. In addition, 18-month duplex follow-up data presented at the 2004 Annual Meeting of the Cardiovascular and Interventional Radiology Society of Europe revealed a 20.7% binary restenosis rate in the sirolimus group (six stenoses and no occlusions in 29 paFrom the Department of Radiology, Centre Hospitalier de l’Universite de Montreal, Notre-Dame Hospital, 1560 Sherbrooke East, Montreal, Quebec, Canada H2L 4M1. Address correspondence to V.L.O.; E-mail: voliva@sympatico.ca