Stephan H. Duda

PURPOSE: To review clinical outcomes of patients with chronic limb ischemia and TASC type C lesions treated with sirolimus-eluting versus bare SMART nitinol self-expanding stents. METHODS: Data were obtained from a randomized, multicenter, double-blinded study conducted in 2 phases. All 93 patients had chronic limb ischemia and superficial femoral artery (SFA) occlusions or stenoses (average lesion length 8.3 cm). In total, 47 patients (31 men; mean age 66.3+/-9.1 years, range 50-84) received the sirolimus-eluting SMART stent and 46 patients (36 men; mean age 65.9 +/-10.8 years, range 38-83) received a bare SMART nitinol stent. Both groups were followed for a mean 24 months. RESULTS: Both the sirolimus-eluting and the bare SMART stents were effective in revascularizing the diseased SFA and in sustaining freedom from restenosis. For both types of stents, improvements in ankle-brachial indices (ABI) and symptoms of claudication were maintained over 24 months (median 24-month ABI 0.96 for the sirolimus group versus 0.87 for the bare stent group, p>0.05). At 24 months, the restenosis rate in the sirolimus group was 22.9% versus 21.1% in the bare stent group (p>0.05). The cumulative in-stent restenosis rates according to duplex ultrasound were 4.7%, 9.0%, 15.6%, and 21.9%, respectively, at 6, 9, 18, and 24 months; the rates did not differ significantly between the treatment groups. The TLR rate for the sirolimus group was 6% and for the bare stent group 13%; the TVR rates were somewhat higher: 13% and 22%, respectively. Mortality rates did not differ significantly between the groups. CONCLUSION: These data demonstrate that the sirolimus-eluting and the bare SMART stent are effective, safe, and free from restenosis in a majority of patients for up to 24 months. Because the restenosis rate in the bare stent group is unexpectedly low, no significant difference could be found between the sirolimus-eluting and the bare SMART stents.

BACKGROUND: Stent implantation for obstructive femoropopliteal artery disease has been associated with poor long-term outcomes. This study evaluated the effectiveness of shape memory alloy recoverable technology (SMART) nitinol self-expanding stents coated with a polymer impregnated with sirolimus (rapamycin) versus uncoated SMART stents in superficial femoral artery obstructions. METHODS AND RESULTS: Thirty-six patients were recruited for this double-blind, randomized, prospective trial. All patients had chronic limb ischemia and femoral artery occlusions (57%) or stenoses (average lesion length, 85+/-57 mm). Patients were eligible for randomization after successful guidewire passage across the lesion. Eighteen patients received sirolimus-eluting SMART stents and 18 patients received uncoated SMART stents. The primary end point of the study was the in-stent mean percent diameter stenosis, as measured by quantitative angiography at 6 months. The in-stent mean percent diameter stenosis was 22.6% in the sirolimus-eluting stent group versus 30.9% in the uncoated stent group (P=0.294). The in-stent mean lumen diameter was significantly larger in the sirolimus-eluting stent group (4.95 mm versus 4.31 mm in the uncoated stent group; P=0.047). No serious adverse events (death or prolonged hospitalization) were reported. CONCLUSIONS: The use of sirolimus-eluting SMART stents for superficial femoral artery occlusion is feasible, with a trend toward reducing late loss compared with uncoated stents. The coated stent also proved to be safe and was not associated with any serious adverse events.

Cellular proliferation, migration, and expression of extracellular matrix proteins and MMPs contribute to neointimal formation upon vascular injury. Wild-type mice undergoing arterial endothelial denudation displayed striking upregulation of receptor for advanced glycation end products (RAGE) in the injured vessel, particularly in activated smooth muscle cells of the expanding neointima. In parallel, two of RAGE's signal transducing ligands, advanced glycation end products (AGEs) and S100/calgranulins, demonstrated increased deposition/expression in the injured vessel wall. Blockade of RAGE, employing soluble truncated receptor or antibodies, or in homozygous RAGE null mice, resulted in significantly decreased neointimal expansion after arterial injury and decreased smooth muscle cell proliferation, migration, and expression of extracellular matrix proteins. A critical role for smooth muscle cell RAGE signaling was demonstrated in mice bearing a transgene encoding a RAGE cytosolic tail-deletion mutant, specifically in smooth muscle cells, driven by the SM22alpha promoter. Upon arterial injury, neointimal expansion was strikingly suppressed compared with that observed in wild-type littermates. Taken together, these data highlight key roles for RAGE in modulating smooth muscle cell properties after injury and suggest that RAGE is a logical target for suppression of untoward neointimal expansion consequent to arterial injury.