Vessel Recoil in Specific CLTI Populations

Early Vessel Recoil Following Below-the-knee (BTK) Artery Treatment With the Spur Peripheral Retrievable Scaffold System in Specific Patient Populations With Chronic Limb-threatening Ischemia (CLTI) - The DEEPER CHALLENGE Single Center Prospective Study

Chronic limb threatening ischemia (CLTI) represents the most advanced stage of peripheral arterial disease (PAD) and is characterized by ischemic rest pain, non-healing wounds, or ischemic gangrene. High-risk PAD populations including patients with end-stage renal disease and or diabetes also experience worse outcomes with significantly increased rates of amputation and mortality.

Although some patients with PAD are best treated with a combination of medical management, exercise and lifestyle modification, revascularization is indicated in those with advanced stages of disease and particularly in the presence of CLTI. Revascularization of below-the-knee (BTK) arteries is required for most patients suffering from CLTI, but treatment faces numerous challenges comprising calcification, small vessel size, long-lesion length and early elastic recoil. With regard to these challenges, numerous innovative techniques and devices have been developed within the past decades to optimize endovascular treatment of BTK vessels.

The Spur Peripheral Retrievable Scaffold System (Spur) was developed to directly address many of these pitfalls of infrapopliteal arterial disease. The premise of the design of the Spur is to provide temporary mechanical scaffolding and to prepare the vessel for treatment with a drug-coated balloon (DCB) to enhance drug absorption by creating channels in the endothelium by the deployed Spur.

The objective of this study is to perform a prospective, single-center, single-arm, non-randomized study to evaluate acute vessel recoil following BTK treatment with the Spur Retrievable Scaffold System in combination with a commercially available DCB in specific patients populations. Specific patient populations that are selected to participate in this study are either at high risk to discover unfavorable outcomes with standard techniques due to a high complexity of lesions and/or patients that are not adequately mirrored in available studies. The patient cohorts that will be studied are diabetics and patients on hemodialysis (for at least 6 months). As women are commonly under-represented in comparable trials, this study requires at least 50% of women for each cohort.

The primary endpoint is vessel recoil within 15 minutes post treatment assessed with angiography. Secondary endpoints will be followed out to 12 months.

Study Overview

• Status: Not yet recruiting
• Conditions: Chronic Limb Threatening Ischemia
• Intervention / Treatment: Other: Vessel recoil measurement 15 minutes post final treatment (angiographically)

• Study Type: Observational
• Enrollment (Estimated): 40

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients with below-the knee (BTK) peripheral arterial disease (PAD) who are either with chronic kidney disease (CKD) requiring hemodialysis for at least 6 months (cohort 1) and/or diabetics (cohort 2) in Rutherford classes (RC) 4 or 5, with ≥ 50% females in each cohort

Description

General Inclusion Criteria:

1. Subject is willing and able to provide informed consent
2. Subject is able to comply with the study protocol and with follow-up
3. Life expectancy >1 year in the investigator's opinion
4. Subject is > 18 years of age
5. Subject must have symptoms of limb ischemia, determined by clinical symptoms of RC 4 or 5, including rest pain (RC 4) and/or minor tissue loss (RC 5), that in the opinion of the investigator are not amenable to conservative medical therapy and require endovascular intervention for alleviation of symptoms and tissue preservation
6. Subject has stenotic, restenotic or occlusive lesions located in BTK vessels in pre-screening with CTA, MRA or angiography prior to the index procedure.

7. Subject suffers from diabetes and/or receives chronic hemodialysis for KD (for at least 6 months)

   • Diabetes cohort: Subject requires for estimated glomerular filtration rate (eGFR) ≥ 25ml/min (within 30 days of procedure)
   • Hemodialysis cohort: Subject has been receiving hemodialysis treatment for ≥ 6 months. (Note: subjects with diabetes who also receive chronic hemodialysis will be excluded from the diabetes cohort and will be included only in the hemodialysis cohort).

Angiographic Inclusion Criteria:

1. Target lesion can be successfully crossed with a guidewire.
2. Target lesion must be located in BTK arteries. Treatment of the distal popliteal segment (P3) is permitted provided that sizing remains appropriate (no more than 4.5 mm in diameter).

3. Target vessel reconstitutes at or above the medial ankle, with the target treated segment extending no more than 10 mm beyond the ankle.

   1. If the anterior tibial or posterior tibial arteries are treated, there must be inline flow to the foot.
   2. If the peroneal artery is treated, there must be at least one collateral supplying the foot.
4. Target vessel reference diameter is measured to be between 2.5 mm to 4.5 mm in diameter.

5. Only one artery may be treated with the Spur device.

   a. Non-target infrapopliteal lesions requiring treatment must be treated prior to treatment of the target lesion. Treatment of the target vessel/lesion with the Spur device may be performed only if treatment of the non-target vessel(s)/lesion(s) does not result in a complication which may compromise the outflow of the target lesion or result in a major adverse limb event.

6. The treated segment is defined as the total length of artery treated with the Spur device. Total target treatment length must be < 250mm with a maximum segment of 220 mm separated by 30 mm of healthy tissue between treated lesions.
7. Successful pre-dilatation of the target lesion as outlined in the procedure instructions, defined as resulting in stenosis ≤ 50%, without resulting flow limiting (Type D or greater) dissection, thrombus, or aneurysm by angiography prior to the insertion of the Spur device.
8. Iliac, SFA and popliteal inflow lesions can be treated during the index procedure. Inflow lesions treated intraprocedure must be treated first, prior to consideration of treatment of infrapopliteal lesions. Inflow lesions must have a healthy vessel segment of >30 mm between the study lesion and the treated segment, defined as ≤ 50% stenosis.
9. The Spur must be deployed from antegrade access.

General Exclusion Criteria:

1. Subject is unwilling or unlikely to comply with the duration of the study (up to 12 months +/-30 days post intervention) in the opinion of the investigator
2. Subject is pregnant or planning to become pregnant during the course of the trial
3. Subject is breastfeeding or planning to breastfeed during the course of the trial
4. Subject has an active and uncontrolled systemic infection, including septicemia or bacteremia
5. Subject has documented active osteomyelitis proximal to the phalanges of the target limb. Osteomyelitis in the digit(s) of the target foot is permitted.
6. Subject has a wound above the ankle and/or a heel wound
7. Subject has planned or had previous major (above the ankle) amputation of the target limb. A planned or previous minor (transmetatarsal amputation or digit amputation) is permitted.
8. Subject with poor and insufficient general condition and/or comorbidities not allowing for endovascular treatment as per the investigator's discretion
9. Diabetes cohort: subject has impaired renal function as defined by an eGFR < 25 mL/min within 30 days of procedure
10. Hemodialysis cohort: subject has been receiving hemodialysis treatment for less than 6 months
11. Subject with inability to comply with antiplatelet and/or anticoagulation therapy as per the facility's standard of care
12. Subject with known allergies or sensitivities to heparin, antiplatelet drugs, other anticoagulant therapies which do not allow for an adequate peri- and post-procedural treatment
13. Subject with known allergies or sensitivities to Paclitaxel or Sirolimus balloon coatings
14. Subject with known allergies or sensitivities to contrast media that cannot be adequately pre-treated prior to the index procedure
15. Subject with known allergies or sensitivities to nitinol or nickel
16. Subject is currently enrolled in another investigational device or drug trial that interferes with the study endpoints.
17. Subject with prior stent(s) within the target vessel, or bypass surgery of or within the target vessel
18. Subject had previous treatment of the target vessel <30 days prior to index procedure

Angiographic exclusion criteria:

1. Angiographic evidence of thrombus within target limb
2. Inability to obtain antegrade access in the limb from which the Spur can be deployed
3. Any lesion characteristics, that in the investigator's opinion, would not be amenable to endovascular standard techniques
4. Significant > 50% stenosis of inflow arteries or unsuccessful treatment of inflow lesions
5. > 50% stenosis, flow-limiting dissection (Type D or greater), aneurysm or thrombus of the target lesion following pre-dilation
6. Inability to obtain additional imaging 15 minutes after target lesion treatment for recoil evaluation.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
CLTI patients on chronic hemodialysis	Other: Vessel recoil measurement 15 minutes post final treatment (angiographically); This study will evaluate early recoil following optimized endovascular treatment (Spur Peripheral Retrievable Scaffold System in combination with a DCB) of BTK vessels in specific high-risk patient populations with CLTI.
CLTI patients with diabetes	Other: Vessel recoil measurement 15 minutes post final treatment (angiographically); This study will evaluate early recoil following optimized endovascular treatment (Spur Peripheral Retrievable Scaffold System in combination with a DCB) of BTK vessels in specific high-risk patient populations with CLTI.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Vessel recoil assessed with angiography	15 minutes post treatment

Secondary Outcome Measures

Outcome Measure	Time Frame
Freedom from unplanned major (above the ankle) amputation	Up to 12 months
Freedom from major adverse limb events (MALE)	Up to 12 months
Freedom from all-cause mortality	Up to 12 months
Freedom from clinically driven target lesion revascularisation (CD-TLR)	Up to 12 months
Target vessel patency determined by duplex ultrasound (DUS)	30 days
Change in ankle brachial index (ABI, or toe brachial index (TBI) alternatively) from baseline	30 days
Change in Rutherford Class from baseline	30 days
Change in Wound, Ischemic, and foot Infection score (WIfI) from baseline	30 days

Collaborators and Investigators

• Sponsor: Medical University of Graz
• Collaborators: ReFlow Medical, Inc.

Study record dates

Study Major Dates

• Study Start (Estimated): March 1, 2026
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): September 1, 2028

Study Registration Dates

• First Submitted: March 6, 2026
• First Submitted That Met QC Criteria: March 6, 2026
• First Posted (Actual): March 12, 2026

Study Record Updates

• Last Update Posted (Actual): March 12, 2026
• Last Update Submitted That Met QC Criteria: March 6, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: peripheral arterial disease; endovascular revascularization; below-the-knee; chronic limb-threatening ischemia; vessel recoil
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Pathologic Processes; Chronic Disease; Disease Attributes; Atherosclerosis; Arteriosclerosis; Arterial Occlusive Diseases; Peripheral Vascular Diseases; Ischemia; Pathological Conditions, Signs and Symptoms; Chronic Limb-Threatening Ischemia; Peripheral Arterial Disease
• Other Study ID Numbers: 1469/2025

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No