No Metal Left Behind: Improving POBA and Potential conflicts of - - PowerPoint PPT Presentation

4/18/2013 1

No Metal Left Behind: Improving POBA and Bioresorbable Stents

Peter A. Schneider, MD Hawaii Permanente Medical Group and Kaiser Foundation Hospital Honolulu, Hawaii

UCSF Vascular Symposium April, 2013

Disclosure

Peter A. Schneider Potential conflicts of interest to report: Consultant to start-ups: Silk Road, Altura, Revascular, Intact Vascular, Pro-med Enter patients in studies: Abbott, Gore, Medtronic, Cordis Modest royalty from Cook

Innovasc

Rutherford class Angiosomal anatomy Runoff

Location and Severity

• f Disease Determines

Type of Reconstruction

TASC

Currently “implant based” Currently “balloon based”

• PTA control arm from 3 randomized, industry-

sponsored device trials – Lesion length = 8.7 cm – 12-month duplex patency = 28%

• Results combined with a survey of medical

literature from 1990 – 2006 – Lesion length = 8.9 cm – 12-month duplex patency = 38%

Catheter Cardiovasc Interv 2007

4/18/2013 2 How Does Balloon Angioplasty Work?

• Equal pressure in all directions around the

circumference of the irregular lumen.

• Pressure increases until it overwhelms the

lesion through compression and plaque fracture.

• When the lesion gives way, the pressure

propagates along the artery and there is usually uncontrolled damage.

Anterior tibial artery dissection after long segment recanalization Above knee popliteal artery dissection at re-entry site SFA dissections

Problems with balloon angioplasty

Achilles heal of balloon angioplasty=dissection Recanalizing Atherosclerotic Vessels

• Balloon Angioplasty –

– Minimally invasive – Technique “dissects” plaque from wall allowing adventitia to expand to maximum diameter – New larger lumen accommodates pre-existing plaque and increased cross-section for blood flow – Problems:

• Plaque is not “molded” but dissected and fractured

in uncontrolled (random) manner

• Plaque often “falls into” lumen obstruction
• Irregularity of “injury” and plaque conformation can

initiate restenosis reaction to injury 8

>40% immediate failure of PTA requiring bailout stents

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SFA Treatment Stent Results

Trial Patency

12 months

Lesion Length

Fast 68% 4.4 cm Resilient 80% 6.2 cm Durability 72% 9.3 cm Astron 65% 9.9 cm Vienna 68% 10.9 cm

TASC A/B

35-50% stent bailout rate in current SFA trials

Femoral-popliteal Disease TASC C and D

C lesions: Surgery preferred unless high risk D lesions: Surgery treatment of choice

SFA Treatment Our Challenge

Surowiec et al. JVS, 2005

Poor results in more complex lesions.

Patency at 12 months Patency at 24 months TASC C stent 83% 80% TASC D stent 54% 28% Above knee PTFE fem-pop 81% 75%

Dosluoglu et al. J Vasc Surg 2008;48:1166

139 limbs

SFA Treatment

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DeRubertis et al. J Vasc Surg 2007 Baril et al. J Vasc Surg 2010

TASC D: Diminished patency at 12 and 24 months. Is it possible: The poor results of long lesions are due as much to stent length as they are to lesion length?

• No. of

patients 12 months 24 months 36 months TASC A/B 46/82 79% 67% 57% TASC C/D 38/35 53% 36% 19%

Primary Patency

Dearing et al J Vasc Surg 2009;50:542.

210 patients

After primary stent, TASC C and D lesions are more likely to fail with

• cclusion rather than

stenosis, lose run-off vessels, and extend the length of contiguous diseased arterial segments than their TASC A and B counterparts.

J Vasc Surg 2011; 53: 658-67

Failed SFA Intervention

Klein et al.Catheter Cardiovasc Interv 2009;74:799

SFA Treatment

Conformational Forces Dramatic changes in configuration with movement.

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Long segment SFA recanalization

Recanalizing Atherosclerotic Vessels

• Stents

– Effective apposition of dissected plaque to expanded lumen wall – Problems

• Large amount of foreign body
• Rigidity of stent / fracture / micro-

trauma

• Restenosis
• Poor options for reintervention

Lower Extremity Stents Too Much Scaffolding Factors Associated with Stent Failure

• Stent overlap
• Chronic outward force
• Stent material
• Strut thickness
• Stent length
• Design/Fracture

Cha et al. Invest Radiol 2003;38:95. Joner et al. J Am Coll Cardiol 2006;48:193. Finn et al. Circulation 2007;115:2435. Lau et al. J Invasive Cardiol 2004;16:411. Sigwart et al. N Engl J Med 1087;316:701. Bertrand et al. J Am Coll Cardiol 1998;32: 562. Verheye et al. Arterioscler Thromb Vasc Biol 2000;20:1168. Nelken et al. Surg Clin N Am 2004;84:1203.

No one volunteers for a full metal jacket! Our Challenge

• Too much metal to artery interaction
• Too much outward force
• Tissue apposition rather than scaffolding

Balloon angioplasty Stents

We need a new paradigm

Bioabsorbables Focal support-Spot stenting, Tack PTA technique

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No Metal Left Behind: Improving POBA and Bioresorbable Stents

Improve Balloon Angioplasty Technique

• Use a balloon that covers the entire length
• f the lesion.
• Increase pressure gradually so that it is
• nly as high as it needs to be to dilate the

lesion.

• Leave balloon inflated for 2-3 minutes.
• Repeat if necessary.

Bioresorbable Vascular Scaffold

CAUTION: Investigational use only. Not available for sale in or outside the U.S.

• Provide acceptable lumen after treatment, then resorb naturally

into the body, leaving the vessel in its native state.

• No implant left behind

– No permanent implant – restore natural vascular response to physiological stimuli and potentially late expansive remodeling – No stimulus for chronic inflammation – Future re-intervention is facilitated – Compatible with non-invasive diagnostic imaging

Rationale: Mechanical support at the treatment site is needed transiently.

Bioresorbable Stent Bioresorbable Stent

Bioabsorable Stent Technology Overview

• Product(s) / Technology overview:
• Polymer (PLLA) vs metal alloy

(magnesium)

• Challenges: degradation rate, control of

radial force, diameter sizing, brittleness, cost

4/18/2013 7 1st Gen Porcine Coronary Safety Study: Representative Photomicrographs (2x)

BVS CYPHER

2 years 1 month 3 months 6 months 1 year 3 years 1 month 3 months 6 months 1 year 2 years 3 years

Representative photomicrographs 2X.

Porcine Coronary Artery Model

A B C D E A B C D E Post-procedure Pre-procedure

Bioresorbable Scaffolds in the Peripheral Vasculature Bioresorbable Scaffolds in the Peripheral Vasculature

Tamai H, Igaki K, Kyo E, Kosuga K, Kawashima A, Matsui S, et al. Circ. 2000; 102(4):399-404. Waksman R. Cardiovascular Revascularization Therapeutics. Washington, D.C., 2007. Erbel R, Di Mario C, Bartunek J, Bonnier J, de Bruyne B, Eberli FR, et al. Lancet 2007; 369:1869-1875. Peeters P, Bosiers M, Verbist J, Deloose K, Heublein B. J. Endovasc. Ther. 2005; 12:1-5. Bosiers M, Peeters P, D’Archambeau O, et al. AMS INSIGHT - Absorbable metals stent implantation for treatment of below-the-knee critical limb ischemia: 6-month analysis. Cardiovasc. Intervent. Radiol. 2009.

Study Device Lesions n Outcome PERSEUS BE Poly-l-lactic acid SFA 45 50% restenosis @ 6-mos. BEST BTK BE Magnesium alloy infrapopliteal 20 90% clinical patency @ 3-mos. AMS INSIGHT infrapopliteal 37 68% restenosis @ 6-mos.

IGAKI Kurz

6 12 18 24 30 20 40 60 80 100

• prim. Patency
• ass. prim. Patency
• sec. Patency

Month Percent

Igaki-Tamai bioabsorbable stent in the SFA Igaki-Tamai bioabsorbable stent in the SFA

Schmidt A. Bioabsorbable stents: The Igaki-Tamai Stent. 2010. www.CRTonline.com.

4/18/2013 8

Bosiers M, Peeters P, D’Archambeau O, Hendriks J, Pilger E, Duber C, Zeller T, Gussmann A, Lohle PNM, Minar E, Scheinert D, Hausegger K, Schulte K-L, Verbist J, Deloose K, Lammer J. AMS INSIGHT - Absorbable metals stent implantation for treatment of below-the-knee critical limb ischemia: 6-month analysis. Cardiovasc. Intervent. Radiol. 2009.

AMS INSIGHT – 6-mos. patency results AMS INSIGHT – 6-mos. patency results

New Studies of Lower Extremity Bioabsorbable Stent

• ESPIRIT I

– SFA and iliac, 30 patients, December 2011 – Bioabsorbable Drug Eluting Vascular Scaffolds – Everolimus, same polymer as ABSORB – New scaffold design, larger diameter, longer length

• ABSORB BTK in CLI

– CLI, infrapopliteal, September 2011 – ABSORB device, CE mark for coronary artery disease

Tack: Key Components

Anchor Fixation: Therapeutic component: 6 pair of anchors tack down focal irregularities Pressure delivered at Focal Points Radiopaque Markers: 6 RO markers aid in visualization Supporting Frame Self expanding Nitinol, supports Inner Circle of 6 Anchor Fixation components Short length (6.0mm), effective implant: less metal, less friction Hinged design prevents watermelon seeding during delivery

Outward Force

Commercially available stent

High outward force Always changing with artery diameter

Tack

Diameter (mm) Substantially lower outward force than commercially available stents Same low outward force over a broad range of diameters

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33

Above-the-knee SFA stenosis

1 yr angio follow-up After Tack

Tack: Above the Knee

Post-PTA dissection Completion Arteriogram After Tack

Tack: IVUS

Dissection Flap Seen Using Intravascular Ultrasound Post Treatment Tack Permits Tissue Apposition

Goal is tissue apposition with positive remodeling

Pre-treatment angio Post-PTA dissection Post-Tack angio One-year angio

Popliteal artery occlusion

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After wire loop subintimal recalization and balloon angioplasty Entry site Re-entry site Tack placement at dissection sites

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After PTA After Tack After PTA After Tack Completion arteriogram

• Minimal Injury

– Acute stent-like result without a stent. – Address major disadvantages of stents, without burning bridges. – Provide a new option, between PTA and stents.

• Incredibly versatile

– Treat multiple lesions, a broad range of vessels, with a single catheter. – ‘Touch-up’ strategy that complements other therapies.

Tack: Minimally Invasive to Minimal Injury

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No Metal Left Behind: Improving POBA and Bioresorbable Stents

Conclusion

• Current treatment paradigms with

angioplasty and stents have limited success.

• No metal or less metal through

bioresorbale stents or focal treatment with less metal implant may provide a more successful option.