The goal of this prospective, multicentre, single arm clinical trial is to assess the safety and effectiveness of Sirolimus-eluting Iron Bioresorbable Peripheral Scaffold System (IBS Titan™) in treating patients with infrapopliteal arterial stenosis or occlusive disease. 100 participants will be implanted with IBS Titan™, and be followed up for 1-month, 6-month and 12-month after discharge.

Inclusion Criteria:

• General criteria

1. Subject between 18 and 85 years old.

2. Subject who can understand the purpose of the trial, voluntarily participate in, and sign the informed consent form, and who are willing to participate until the 12 months follow-up.

3. Subject has symptomatic Critical Limb Ischemia, Rutherford category 3-5.

4. Subject requires primary treatment of de novo infrapopliteal lesions.

   • Angiographic criteria

5. Target lesion stenosis ≥ 70% or occlusion in no more than two infrapopliteal arteries.

6. The distal margin of the target lesion must be located ≥ 10 cm proximal to the proximal margin of the ankle mortise.

7. The target lesion must be located in the proximal 2/3 of native infrapopliteal vessels, length is ≤ 200mm, with vessel diameter of 2.5-4 mm.

8. Only two infrapopliteal vessels are allowed to be treated at the same time.

9. A maximum of two stents can be deployed at one target vessel.

10. There must be at least one unimpaired artery (< 30% stenosis) to the ankle.

Exclusion Criteria:

• General criteria：

1. Severe renal insufficiency, hepatic dysfunction (Cr > 2 times normal limit or renal dialysis, ALT or AST > 5 times normal limit).

2. Major amputation before index procedure or plan for major amputation.

3. Any coagulation disorder.

4. Lower extremity arteries surgery or thrombolytic therapy in the ipsilateral extremity in the past 6 weeks.

5. Stroke within 3 months, or stroke with severe hemiplegia and aphasia sequelae more than 3 months before inclusion in the study.

6. Acute myocardial infarction or acute ischemia within 30 days before inclusion in the study.

7. Thromboangiitis obliterans (Buerger's disease).

8. Any previous treatment with drug eluting balloon or drug eluting stent within 90 days before inclusion.

9. Any surgery in target vessel before index procedure.

10. Volume reduction operation in target vessel before inclusion.

11. Subject known to be allergic to aspirin, heparin, clopidogrel, Polylactic acid, iron, zinc and its degradation products, contrast agents, sirolimus, etc., and those who cannot tolerate postoperative dual anti-platelet therapy.

12. Subject with a history of iron overload or iron disorders related diseases, such as hereditary hemochromatosis, etc.

13. Subject is currently participating in another clinical trial that has not yet completed its primary endpoint.

14. Women of child-bearing potential not using an effective contraception; pregnant or lactating women.

15. Subject is not suitable to participate in the trial as per investigators discretion.

16. Life expectancy ≤ 12 months as per investigators judgement.

    • Angiographic criteria

17. The inflow tract (including ipsilateral iliac artery, femoral artery, popliteal artery) has lumen stenosis >30% with or without intervention.

18. The inflow tract (including ipsilateral iliac artery, femoral artery, popliteal artery) has > 150 mm stenosis or occlusion before treatment.

19. Significant stenosis (≥50% stenosis) of the arterial outflow tract perfused by the target vessel.

20. In-stent restenosis in any lower extremity artery.

21. Thrombosis in target vessel, or acute thrombosis requiring thrombolysis and thrombectomy.

22. Guide wire cannot pass target lesion.

23. Angiography suggests intraoperative thromboendarterectomy, percutaneous transluminal rotational atherectomy or laser therapy are needed.

24. Aneurysm of lower extremity artery in the ipsilateral leg.