This study aims to evaluate the effectiveness and safety of the Smart flex stent system in treating long femoropopliteal native lesions.

One hundred twenty patients with lesion lengths longer than 15 cm will be included. Patients will be invited for a follow-up visit at 1, 6, 12, and 24-month post-procedure. The primary effectiveness endpoint of the study is the primary patency at 12 months. The primary safety endpoint is freedom of major adverse events (MAEs) at 12 months. Secondary endpoints include acute procedure success rate; primary patency rate at 1, 6, and 24 months; freedom from TLR at 1-, 6-, 12, and 24-month follow-up; primary and secondary sustained clinical improvements at 1-, 6-, 12- and 24-month follow-up; Freedom of MAEs at 1-, 6-,12- and 24- month follow-up; change of quality of life at 1-, 6-,12- and 24- month follow-up.

Inclusion Criteria:

1. The patient presented a score from 2 to 5 following Rutherford classification
2. The patient is willing to comply with specified follow-up evaluations at the specified times
3. The patient is >18 years old
4. Patient understands the nature of the procedure and provides written informed consent before enrolment in the study
5. The patient has a projected life expectancy of at least 24 months
6. Before enrolment, the guidewire has crossed the target lesion
7. Target lesion length ≧150mm by angiographic estimation
8. Stenosis > 50% or occlusion in the femoropopliteal artery
9. There is angiographic evidence of patent distal popliteal artery and at least one distal runoff to the foot

Exclusion Criteria:

1. Previous bypass surgery or stenting in the target vessel
2. Patients who exhibit acute intraluminal thrombus at the target lesion vessel
3. Patients with known hypersensitivity or contraindication to any of the following medications: Nitinol-titanium, antiplatelet therapy, anticoagulants, or thrombolytics therapy
4. Pregnant women or Female patients with potential childbearing
5. Use of thrombectomy, atherectomy, or laser devices during the procedure
6. Untreated inflow disease of the ipsilateral pelvic arteries (more than 50% stenosis or occlusion
7. The patient is currently participating in another investigational drug or device study that has not reached the primary endpoint.
8. Significant renal dysfunction (Serum creatinine >2.0mg/dl)
9. Patient with Known allergy to contrast media