Tibial Scaffolds: Which Ones and Why?

John Rundback, MD

Faculty Disclosures

John Rundback: Consultant – Daiichi Sanko, Philips, Toray, Vesper, SAB: Abbott, Boston Scientific, Medtronic, National PI: EXIMO; Grant/Research Support – NO INDIVIDUAL COMPENSATION SITE PI: Medtronic, NIH, Biologic, Cordis, PQ Bypass, Limbo, Surmodics, Intact Vascular, SAVAL, PLX-CLI03, Boston Scientific, Site Co-PI: Ekos, National PI: Eximo; Speakers’ Bureau – Abbott, Bard, Cook, CSI, Gore, Medtronic; Other Financial or Material Support – EXIMO (Options)Brand names are included in this presentation for participant clarification purposes only. No product promotion should be inferred.

Challenges with BTK AngioplastyMechanisms of early PTA failure below the knee:1,2

• Diffuse, long disease in smaller, lower flow vessels• Multivessel, bifurcation disease• Medial calcium, vessel recoil

Post-PTA dissection remains prevalent3

• ≥30.7% dissection rate3,4

– Under-reported (medial calcium, bone interference and small RVD)5

• Can appear as residual stenosis or recoil3,6

• Predictor for infrapopliteal restenosis6

1Geary, Epidemiology and Pathogenesis of Restenosis 20072Bakker, LINC 20193Zeller, J Am Coll Cardiol 2014

4Fanelli, J Cardiovasc Surg 20145Razavi, J Vasc Interv Radiol 20146Schillinger, Radiology 2002

Bakker, LINC 2019

Shammas, Vasc Dis Mgmt 2019

• 5 RCT / 611 pts (DES=294; control=307)

• Short lesions (median 26.8 mm)• DES superior to control (POBA/BMS)

Ø TLR (OR 0.31; CI: 0.18 to 0.54; p < 0.001)Ø Restenosis (OR: 0.25; CI: 0.15 to 0.43; p < 0.001)Ø Amputation (OR: 0.50; CI: 0.26 to 0.97); p = 0.04)

Fusaro M, et al. JACC Cardiovasc Interv. 2013;6(12):1284-1293.

Siablis D, et al. JACC Cardiovasc Interv. 2014;7(9):1048-1056.

The IDEAS Randomized Controlled Trial

Siablis D, et al. JACC Cardiovasc Interv. 2014;7(9):1048-1056.

DES: 1.35 ± 0.2DEB: 1.15 ± 0.3P = 0.6

DES: 3.6 ± 1.5DEB: 4.3 ± 1.6P = 0.16

• 50 patients, 25 (25 lesions) DCB, 25 (30 lesions) DES

• Mean lesion length: 148±56 DCB vs 127±46 DES p=0.1

• CTO: 3/25(12%) DCB vs 7/30(23%) DES

Recoil may be important

ONE-YEAR FOLLOW-UP

Spreen MI, et al. J Am Heart Assoc. 2017;6(4). pii: e004877.

Varcoe RL, et al. JACC Cardiovasc Interv. 2016;9(16):1721-1728.

Drug-Eluting BVS Results (Absorb BTK)

technology with larger numbers and longer follow-up(9). This study has demonstrated rates of freedomfrom binary restenosis and target lesion revasculari-zation of 96.0% at 12 months of follow-up, promisingearly results in the interventional practice of below-the-knee arteries, which began 25 years ago.

The endovascular treatment of crural blood ves-sels began with simple percutaneous transluminalangioplasty (PTA), documented in the first case re-ports from the early 1990s (11). Those initial expe-riences were collected in a 2008 meta-analysis thatanalyzed 30 studies using infrapopliteal angioplastypublished between 1990 and 2006. That analysisfound patency rates that were disappointing by to-day’s standards: cumulative primary patency of just65.0%, 58.1%, and 48.6% at 6, 12, and 36 months,respectively (12). Although this was a historicalsnapshot, those PTA results remain consistent withresults observed in more recent randomized studies(58% to 66%, 12-month primary patency), in whichangioplasty has been included as a treatment armfor Inter-Society Consensus for the Management ofPeripheral Arterial Disease types A and B disease(3,10). Bare-metal stents have been used as bothprimary therapy and for bailout after PTA, andalthough they are effective for the treatment ofelastic recoil and flow-limiting dissection, severalstudies have demonstrated that they offer nopatency advantage over simple PTA (10,13–15). Incontrast, a number of randomized controlled trialsand meta-analyses have demonstrated the superi-ority of metal DES over both PTA and bare-metalstenting (1–3,16,17). These antiproliferative drug-coated devices have achieved excellent primarypatency rates of 78% to 85% at 12 months in lesionsrange from 17 to 31 mm in length (1–3). Suchconsistently encouraging results from high-qualitytrials have made DES the gold standard for thetreatment of short, atherosclerotic disease againstwhich all other therapies must be judged. The 12-month primary patency of 96% in the presentstudy compares favorably with those DES results,using a device which has advantages over thesepermanent metallic implants.

BVS devices are a concept with inherent advan-tages over metal DES. In theory, they provide thesame mechanical properties during the blood vesselremodeling phase that follows angioplasty, whiledelivering antiproliferative drug directly to the siteof vascular injury to minimize neointimal hyper-plasia. However, once those functions are complete,the device begins a gentle resorption process thatsees it disappear entirely, leaving the native arteryfree of the metal assembly that would restrict itsability to pulsate, vasoregulate, and adapt. Prior toAbsorb, a number of other bioresorbable scaffoldshave been used in human clinical trials. The firstwas the Igaki-Tamai stent (Kyoto Medical Planning,Kyoto, Japan), which has a helical zig-zag designalso made of PLLA, but with no antiproliferative

FIGURE 3 Primary Patency and Target Lesion Revascularization

Kaplan-Meier curve demonstrating clinically driven target lesion revascularization(CD-TLR) and primary patency. SE ¼ standard error.

FIGURE 4 Rutherford Category

Change in Rutherford category for all 38 limbs from presentationto mean of 12-month follow-up.

Varcoe et al. J A C C : C A R D I O V A S C U L A R I N T E R V E N T I O N S V O L . 9 , N O . 1 6 , 2 0 1 6

Absorb Bioresorbable Vascular Scaffold, Below the Knee A U G U S T 2 2 , 2 0 1 6 : 1 7 2 1 – 8

1726

• 37 limbs in 32 pts• CLI 73% of limbs• Absorb BVS• Mean lesion 18.7 mm

95% 1-yr patency85% 2-yr patency

Varcoe RL, et al. JACC Cardiovasc Interv. 2016;9(16):1721-1728.

Everolimus 100 mcg/mm2

Tibial Scaffolds

WHICH ONES?

Currently, coronary DESSoon, TacksEventually, purpose-built scaffolds

WHY?

RecoilDissectionBest hemodynamic result?

Dr. Lookstein – long tibial stentsDr. Saab – SAVAL trial

Dr. Beasley – STAND trial

Dr. Adams

Boston Scientific SAVAL™

DES System

Temporary Spur Stent

Spur System by Reflow Medical Inc.

Micro Medical Solutions MicroStent®

Dissection – Treatment Options• Very limited dsxn

– Observe or PTA – 2-5 min low pressure inflation

• Low calcium, isolated, persistent– Tack

• Calcified, resistant, confluent– DES

• Long, diffuse – PTA, new stent designs (SAVAL)

Resolute Coronary DES

Resolute Coronary DES

TOBA II BTK 6-Month

Pivotal DataBTK Tack® Implants

4 pre-loaded nitinol implants6 mm deployed length

Each implant self-sizes to tapering BTK anatomy1.5 – 4.5 mm RVD

OTW Delivery System4F / .014”

150cm working lengthAccurate (≤1 mm) deployment

6 MTH FU

6M K-M Tacked Segment and Lesion Patency

87.7%87.3%

Pate

ncy

(%)

0

10

20

30

40

50

60

70

80

90

100

Time in Days0 30 60 90 120 150 180 210

Days Tacked Segment Patency (95% CI) At Risk

30 99.7% (99.0%,100%) 300

180 87.7% (84.0%,91.4%) 264

210 82.1% (77.7%,86.4%) 0

Days Target LesionPatency (95% CI) At Risk

30 99.5% (98.5%,100.0%) 196

180 87.3% (82.7%,92.0%) 172

210 81.2% (75.8%,86.7%) 0

*DUS flow or no flow at 6 m; Tacked segment is defined as a Tack implant + 5 mm of arteryproximal and distal; Tacks within 1 cm are considered same segment†DUS flow or no flow at 6 m in PTA treated length

Tacked Segment Patency: 87.7%

Target Lesion Patency: 87.3%Tacked Segment Patency*

Target Lesion Patency†

Secondary Endpoint % (n/N)[95% CI]1

PerfGoal

Endpointp-value1

6m Tacked segment(s) patency*

ITT 82.1% (247/301)[77.2%, - ]

64%MET

<0.0001PP 81.6% (230/282)[76.7%, - ]

(ITT population)

1Continuity corrected z-test for one proportion.One sided lower 97.5% confidence bound.

Tibial scaffolds are currently predominantly bailout technologies

BUT…

1. Tacks have the potential to allow more aggressive (“optimized”) balloon angioplasty

2. New platforms may allow primary treatment of longer and more complex lesions to improve clinical outcomes

Conclusion