Drug-eluting stents show promise for periphery

Drug-eluting stents offer a potentially effective means of preventing restenosis in peripheral superficial femoral artery disease, although more clinical studies are needed, according to a group of German radiologists.

The infra-inguinal arteries are usually affected in patients with peripheral vascular disease. A relatively small vessel lumen with high plaque burden and a high frequency of primary occlusions makes the superficial femoral artery (SFA) difficult to treat effectively, said Dr. Thomas Jahnke, a radiologist at University Hospital Schleswig-Holstein in Kiel.

While stents might offer a solution, long-term patency is compromised by neointimal hyperplasia, Janke said in a presentation at the annual meeting of the Cardiovascular and Interventional Radiology Society of Europe, held in Antalya, Turkey, in late September.

Among the most promising strategies for preventing the problem of neointimal hyperplasia is the use of drug-eluting stents, said Dr. Stephan Duda, vice chair of diagnostic radiology at University Hospital in Tubingen. Duda presented initial results from the SIROCCO feasibility study, in which drug-eluting stents and bare devices were used to treat SFA obstruction.

In the first phase of the multicenter double-blind prospective trial, half of the 36 patients with symptomatic peripheral atherosclerotic disease were treated with bare self-expanding nitinol stents (Smart stent, Cordis). The other 18 patients received a sirolimus-eluting stent, which delivered a slightly lower dose than the 1200 g delivered by the coronary stent (Cypher, Cordis). The stent was 8 cm long and 1 to 2 mm larger than the vessel diameter (6 to 7 mm). A maximum of three stents per patient were implanted.

All the patients in the SIROCCO study had obstructive, native, de novo, or restenotic lesions 7 to 20 cm in length or occlusions in the SFA ranging from 4 to 20 cm. The mean lesion length was 85 mm, and 57% of patients had total occlusions.

In-stent angiography results at six-month follow-up showed a minimal luminal diameter of 3.98 mm in the slow-release group compared with 3.49 mm in the control patients. The mean stent diameter was 5.02 mm in the drug-treated patients versus 4.58 mm in the controls. Late lumen loss was 0.38 mm for the slow-release group and 0.82 mm for the controls.

Restenosis (estimated to occur at rates of 22% to 65% 12 months after PTA procedures and/or stent placement) was zero in the patients who were treated with drug-eluting stents. Even in the control group, the restenosis rate was low at 11.6%.

No occlusions were observed in the sirolimus group, compared with one occlusion in the bare stent group at six months. None of the patients in either group required revascularization. Serious adverse events included inflammation of the treated leg in two members of the sirolimus group and two unrelated deaths.

The next phase of the SIROCCO study will include 57 patients to corroborate the findings of the early results. The study has been amended to include a longer follow-up. According to Duda, the slow-eluting platform appears to be better than fast-eluting stents, and the 2.5 to three-week elution rates may need to be longer than four weeks.

Patients with peripheral SFA disease who are most likely to benefit from sirolimus-eluting stents include high-risk patients with diabetes, heavily calcified lesions, or long occlusions, he said.

A number of new-generation drug-eluting stents are undergoing studies, including sirolimus analogs, everolimus (Biosensors, Guidant), ABT 578 (Abbott, Medtronic), and tacrolimus (Jomed, Abbott). Additionally, an ongoing study of the Palmaz Genesis stent in renal arteries is under way.

For more information from the Diagnostic Imaging archives:

FDA sounds alarm over drug-eluting stent

Renal artery stenting scores good grades in trials

Trials reveal need for changes in drug-eluting stent designs

Imaging and stenting provide effective therapy