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Bioabsorbable Stents                  Design Considerations                   Robert S. Schwartz, MD                  Minn...
Disclosures:Abbott Vascular: SAB, Research SupportBoston Scientific: SAB, Research SupportREVA: Minor Equity  The Minneapo...
Bioresorbable Stents – Generation 1Leave only natural vessel long termMay reduce long term risk of thrombosisMay reduce...
Rationale and Goals (from BVS)Revascularize the vessel like a metallic DES, then resorb naturally into the body.Leave no...
Desire for a        ‘Vascular Restoration Therapy’?       Revascularization                               Restoration     ...
Goals from the RationaleNo stimulus for chronic inflammation – potentially reduces the need for long-term dual antiplatel...
Abbott Vascular Everolimus-Eluting                 Bioresorbable Vascular Scaffold ML VISION Delivery                     ...
Bioresorbable Polymer                                  Everolimus/PDLLA Matrix                                    Coating ...
Porcine Coronary Arteries                     4                                                                          B...
BVS Stent Objectives                   uniform strut distribution                   even support of arterial wall       ...
Radial Strength                     (mmHg)                               Radial Strength MSI Testing                      ...
What is the Minimum Duration of Radial Scaffolding?                     Quantitative angiographic study in 342 consecutive...
Radial Strength Over Time                                                            In-Vitro Degradation Testing (soaked ...
Potential for Mechanical                     ConditioningDesign Goals: Gradual disappearance of                           ...
Mechanical Conditioning in Pre-                 Clinical Model (Porcine)               Transmission Electron Microscopy (T...
Bioresorbable Stent Tradeoffs             Degradation profile             Vascular compatibility                       v...
REVA Medical – Stent Features                                 7Fr compatible                 Coating:   Slide and lock ...
REVA Medical – Polymer Tyrosine derived polycarbonate polymer specifically formulated for   bioresorbable stent Benign bre...
Metal Alloys – Biotronik       Absorbable Metal Stent (AMS)                                      5Fr compatible          ...
Biotronik – Degradation Rate AMS 2 – Modified Mg Alloy and Design                                                        ...
Bioresorbable Stent Technologies                           TAXUS® Liberté*    REVA DERS3+               BVS+              ...
Bioabsorbable Stents                  Design Considerations                   Robert S. Schwartz, MD                  Minn...
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Des bioabsorbable stents tct 2010

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Des bioabsorbable stents tct 2010

  1. 1. Bioabsorbable Stents Design Considerations Robert S. Schwartz, MD Minneapolis Heart InstituteThe Minneapolis The Minneapolis HeartHeart Institute Institute Foundation
  2. 2. Disclosures:Abbott Vascular: SAB, Research SupportBoston Scientific: SAB, Research SupportREVA: Minor Equity The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  3. 3. Bioresorbable Stents – Generation 1Leave only natural vessel long termMay reduce long term risk of thrombosisMay reduce need for long term anti-platelettherapyIncreased options for retreatment (ISR, distallesion, CABG)Increased CT / MR imaging capabilityAppeals to concern over permanent implantNeed Improved Deliverability The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  4. 4. Rationale and Goals (from BVS)Revascularize the vessel like a metallic DES, then resorb naturally into the body.Leave no permanent metallic implant.No permanent scaffold – restores natural vascular response to physiological stimuli and potentially permits late lumen expansion. *Serruys PW, et al., Circulation 1988; 77: 361. Serial study suggesting vessels stabilize 3-4 months following PTCA. The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  5. 5. Desire for a ‘Vascular Restoration Therapy’? Revascularization Restoration Resorption Support Full Mass Loss & Bioresorption Everolimus Elution Mass Loss 1 3 6 Mos 2 Yrs Platelet Deposition Matrix Deposition Leukocyte Recruitment Re-endothelialization SMC Proliferation and Migration Vascular FunctionForrester JS, et al., J. Am. Coll. Cardiol. 1991; 17: 758.Oberhauser JP, et al., EuroIntervention Suppl. 2009; 5: F15-F22. The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  6. 6. Goals from the RationaleNo stimulus for chronic inflammation – potentially reduces the need for long-term dual antiplatelet therapy.Future re-intervention (PCI and CABG) is facilitated.Provide compatibility with non-invasive diagnostic imaging (MR/CT), allowing non-invasive follow-up. *Serruys PW, et al., Circulation 1988; 77: 361. Serial study suggesting vessels stabilize 3-4 months following PTCA. The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  7. 7. Abbott Vascular Everolimus-Eluting Bioresorbable Vascular Scaffold ML VISION Delivery Bioresorbable Bioresorbable Everolimus System Device Platform Coating• Seven • Polylactide (PLLA) • Polylactide (PDLLA) • Similar dose and generations of • Naturally coating release rate to MULTI-LINK resorbed, fully XIENCE V • Fully biodegradable success metabolized• World-class deliverabilityAll illustrations are artists’ renditions The Minneapolis The Minneapolis Heart Heart Institute 7 Institute Foundation
  8. 8. Bioresorbable Polymer Everolimus/PDLLA Matrix Coating Thin coating layer Amorphous (non-crystalline) 1:1 ratio of Everolimus/PLA matrix Drug/polymer matrix Conformal Coating, 2-4 µm thick Polymer backbone Controlled drug release PLLA Backbone Highly crystalline Provides device integrityThe Minneapolis Processed forThe Minneapolis Heart increased radialHeart Institute Institute Foundation
  9. 9. Porcine Coronary Arteries 4 BVS Cypher 3 Less Inflammation thanInflammation Score 2 Cypher 1 Minimal Inflammation 0 1 3 6 9 12 18 24 36 48 Time (months) Inflammation score ≤ 1 = background The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  10. 10. BVS Stent Objectives uniform strut distribution even support of arterial wall Cohort A Lower late scaffold area loss Maintain radial strength for at least 3-4 months Storage at room temperature Improved device retention Cohort BThe Minneapolis The Minneapolis HeartHeart Institute Institute Foundation
  11. 11. Radial Strength (mmHg) Radial Strength MSI Testing 1800 1600 1400 1200 1000 991 883 800 600 400 200 0 BVS Cohort B XIENCE V Radial strength comparable to metal stent at T=0Tests performed by and data on file at Abbott Vascular. The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  12. 12. What is the Minimum Duration of Radial Scaffolding? Quantitative angiographic study in 342 consecutive patients at 1, 2, 3, and 4 months n = 342 patients (n = 93 at 30-day F/U; n = 79 at 60-day F/U; n = 82 at 90-day F/U; n = 88 at 120-day F/U) p < 0.00001 p < 0.00001 .The lumen appears to stabilize approximately three months after PTCASerruys PW, et al., Circulation 1988; 77: 361. The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  13. 13. Radial Strength Over Time In-Vitro Degradation Testing (soaked at 37° C PBS) 1400 1251 1213 1209 1183 1224 1200 1132 1125 1134 1124 1158 Radial Strength (mmHg) 1000 1127 955 3 – 4 Month Goal 800 600 400 200 0 0 50 100 150 200 250 300 t (days)Tests performed by and data on file at Abbott Vascular. The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  14. 14. Potential for Mechanical ConditioningDesign Goals: Gradual disappearance of Vessel recovers the ability to supportive scaffold respond to physiologic stimuli Vascular Function Shear stress & pulsatility Support Tissue adaptation Structure and functionalityMechanical conditioning may lead to improved cellular organization and vascular function ‘Vascular Restoration Therapy’ The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  15. 15. Mechanical Conditioning in Pre- Clinical Model (Porcine) Transmission Electron Microscopy (TEM) Smooth Muscle α-Actin Dense bodies At 36 months, SMCs are well organized and have undergone transformation to a functional, contractile phenotypeTests were performed by and data are on file at Abbott Vascular. The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  16. 16. Bioresorbable Stent Tradeoffs Degradation profile Vascular compatibility vs Profile Radial strength Recoil Vessel conformability Standard implant/storageThe Minneapolis The Minneapolis HeartHeart Institute Institute Foundation
  17. 17. REVA Medical – Stent Features 7Fr compatible Coating: Slide and lock profile Tyrosine-derived design Polycarbonate + Ptx Stent Material: Tyrosine-derived Polycarbonate Iodine impregnated for RO Loss of radial strength Degradation Implant 1-year 2-year The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  18. 18. REVA Medical – Polymer Tyrosine derived polycarbonate polymer specifically formulated for bioresorbable stent Benign breakdown products (amino acids, ethanol, and CO2) Ability to vary degradation rate Radiopaque (iodine impregnated into polymer) Same polymer used for drug coatingREVA Clinical Polymer:86.75% I2DTE-co-10%I2DT-co-3.25%PEG2000carbonate) REVA Tyrosine Derived Polycarbonate Stent The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  19. 19. Metal Alloys – Biotronik Absorbable Metal Stent (AMS) 5Fr compatible profile Conventional  No Drug/Drug Coating stent designNo radiopaque Stent Material: markers 93% Mg+7% Other Loss of radial strength DegradationImplant 6-Wks 3-Months The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  20. 20. Biotronik – Degradation Rate AMS 2 – Modified Mg Alloy and Design Slower degradation rate Improved stent strength Drug component/delivery? 4-Wk HistologyImages from “Is it a dream? Drug Eluting Absorbable Metal Stent (DREAMS)” presentation at Euro PCR 2007 given by Dr. Ron Waksman The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  21. 21. Bioresorbable Stent Technologies TAXUS® Liberté* REVA DERS3+ BVS+ Biotronik AMS+Design Conventional Slide and Lock Conventional ConventionalCrimped Profile 0.047” (5F) 0.055” (6F) 0.053” (6F) 0.048” (5F)Recoil 2.6% 1% 8% 7%Storage None None Freezer (-15˚ C) NoneStent Material Stainless steel Tyrosine-derived PLLA 93% Mg + 7% rare polycarbonate earth metals Strength Until Permanent ~ 3-6 months ~ 3-6 months ~ 1 week Resorption N/A, permanent ~ 2 years ~ 2-3 Years ~ 3 months Deg. Products N/A, permanent CO2, Amino Acids, Lactic acid Magnesium, other Ethanol metalsVisibility Whole Stent Whole stent Stent markers Balloon markersDrug/ Paclitaxel/ Sirolimus/ Everolimus/ Pimecrolimus/Coating Translute polymer Tyrosine derived PDLLA PLGA polycarbonate The Minneapolis The Minneapolis Heart Heart Institute Institute Foundation
  22. 22. Bioabsorbable Stents Design Considerations Robert S. Schwartz, MD Minneapolis Heart InstituteThe Minneapolis The Minneapolis HeartHeart Institute Institute Foundation

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