bioabsorbable stents: early clinical results dr angela hoye mb chb, phd senior lecturer in...
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Bioabsorbable stents: early clinical results
Dr Angela Hoye MB ChB, PhD
Senior Lecturer in Cardiology
Hull & East Yorkshire Hospitals
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MY CONFLICTS OF INTEREST ARE:
Clinical Events Committee member for SPIRIT II, V and SPIRIT Woman, fees paid by Abbott Vascular Inc
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• Review the clinical evidence available
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Igaki-Tamai stent (Kyoto Medical Planning, Japan)• Poly-L-lactic acid (PLLA) self-expanding stent
• Strut thickness of 170µm
• FIM study of 50 patients (63 lesions)– 1 in-hospital stent thrombosis and Q-wave MI
– 1 non-cardiac death
– TLR (all with PCI): at 6 months 12%
at 12 months 17%
at 4 years 18%
– Late loss index (in the first 15 patients) was 0.48mm at 6 months
• Further studies in the SFA with this stent demonstrated feasibility and safety in deployment of these stents over a length of 70 mm – the stent has CE mark for use in PVD.
Tamai et al Circulation 2000;102(4):399-404; Tamai CCT 2004
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Magnesium stent (AMS, Biotronik)• Balloon-expandable magnesium alloy
absorbable stent• The first clinical trial was performed in
20 patients with severe PVD with disease in the proximal two-thirds of one or more infrapopliteal arteries
• All were candidates for amputation and underwent PCI with the magnesium stent on a compassionate basis
• Following pre-dilatation, the 3.0×15 and 3.5×15 mm AMS were successfully deployed with good angiography and ultrasound results
• At 3 and 6 months post-implantation, the stent patency rates were 89% and 78%, respectively
• At 3 months, USS & MRI demonstrated complete AMS absorption • At 6 months follow-up, only 1 patient required amputation
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Magnesium stent (AMS, Biotronik)• Coronary FIM multicentre study of 63 patients – PROGRESS-AMS
• The primary endpoint was MACE at 4 months and ischemia-driven TLR
• Safe: no death, no MI, no stent thrombosis
• The stent was well-expanded on deployment with no immediate recoil
• High restenosis rate with an in-stent late loss of 1.08 ± 0.49mm
Erbel et al Lancet 2007;369:1869-75Waksman et al JACC Cardiovasc Interv. 2009 Apr;2(4):312-20
Cumulative frequency curves of in-segment luminal narrowing before, immediately after and at 4 months follow-up after AMS
Ischaemia-driven TLR was 24% at 4 months, and 45% at 1 year
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Erbel et al Lancet 2007;369:1869-75
Magnesium stent (AMS, Biotronik)• PROGRESS-AMS: results of IVUS
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Magnesium stent (AMS, Biotronik)
Waksman et al JACC Cardiovasc Interv. 2009 Apr;2(4):312-20
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Magnesium stent (AMS, Biotronik)• Return of coronary vaso-reactivity following absorption
• 5 patients treated with AMS compared with 10 treated with metal stents
• QCA was measured on two orthogonal views at 0.2mm intervals throughout the stented segments and a 1cm proximal reference segment before and after administration of 2mg intra-coronary ISDN
Ghimire et al Eurointervention 2008;4:481-4
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REVA stent (Reva Medical)• Polycarbonate tyrosine-derived stent which
breaks down to amino acids, alcohol, and carbon dioxide. It is impregnated with iodine to improve radio-opacity
• Balloon-expandable and has a ratchet-like system so that as it expands the stent ratchets open and can't reclose down
• Radial support for 6 months• Stent absorption over 2 years• Interim analysis of 27 FIM patients demonstrated “unfavourable
results between 4 and 6 months with higher than expected TLR driven by reduced stent diameter”
Grube TCT 2008
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REVA stent (Reva Medical)
OCT performed at 12 months demonstrated the presence of neointimal tissue covering the entire treated segment, and signs of stent absorption
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REVA stent (Reva Medical)• Second generation stent with sirolimus on the
abluminal surface• Absorption time: 4 years• Duration strength 4-6 months• FIM due to start shortly
Pollman Eurointervention Suppl 2009,F54
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BVS stent (Abbott Vascular)• PLA backbone, releases everolimus (80% by 30 days)• Struts are 150µm, radiopaque markers at either end• ABSORB cohort A FIM trial• 3x12 then 3x18mm BVS• Simple lesions
Ormiston et al Lancet 2008Serruys et al Lancet 2009
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BVS stent (Abbott Vascular)• MACE rate was 3.4% (1 patient)• No “stent” thrombosis• In-”stent” late loss at 6 months was 0.43mm (0.47mm at 2 yrs)• Vessel and scaffold area changes:
Ormiston et al Lancet 2008Serruys et al Lancet 2009
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• Vasomotion study (n=7)• Methergine (non-endothelial
dependent vasoconstrictor)• Shows the vessel is no
longer “splinted”
• Comparison of a Cypher stent and BVS on MSCT
• Allows non-invasive FU with quantification
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• Results of ABSORB Cohort A were encouraging with only 1 MACE and resorption largely complete by 2 yrs
• The Cohort A scaffold had shrinkage at 6 months that was the major contributor to the late loss
device
– Same strut material, thickness, drug (everolimus) and resorption time
– More uniform strut distribution, vessel support and drug application
0.871.25
BVS 1.0 BVS 1.1
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BVS stent (Abbott Vascular)• ABSORB Cohort B FIM trial• 3.0x18mm BVS to treat lesions ≤14mm in length
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No thrombosis by ARC or ProtocolMACE: cardiac death, MI, ischaemia-driven TLRTLF: cardiac death, MI, ischaemia-driven TLR, ischemia-driven TVR
BVS stent (Abbott Vascular): Cohort B FIM trial
30 daysN=101
6 monthsN=101
Cardiac death (%) 0 0
MI (all non-Q-wave) (%) 2 3
Ischaemia-driven TLR (%) 0 2
PCI 0 2
CABG 0 0
MACE (%) 2 5
TLF (%) 2 5
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In-”stent” late loss of BMS / Xience V / BVS 1.0 / BVS 1.1
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Δ Vessel Area = +0.3%
Δ Stent Area = -11.8%
Δ Lumen Area = -16.8%
NIH Area (mm2) = 0.29% VO = 5.3%
ABSORB: BVS 1.0
Δ Vessel Area = +2.4%
Δ Stent Area = -2.0%
Δ Lumen Area = -3.1%
NIH Area (mm2) = 0.08 % VO = 1.2%
ABSORB: BVS 1.1
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• Appears safe and effective • Limitations: Markers difficult to see in large patients
– Not tested in more complex anatomy– Should not re-introduce an undeployed stent as less
securely mounted– Aggressive post-dilatation will cause strut fracture
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Summary & conclusions• Potential advantages of biodegradable stents:
– Shorter duration of dual anti-platelet therapy– Recovery of endothelial function– No remaining prosthesis therefore enabling future revascularization without
the increased MACE associated with treating an “in-stent restenosis”; no “full metal jacket”
– Potential for applications such as angiogenesis and gene transfer– Compatibility with non-invasive imaging modalities (CTA and MRI)
• The potential (long-term) advantages of biodegradable stents have to be weighed up against the limitations:– Lower strength compared to metallic stents → recoil– Relatively poor crossing profile– Radiolucent
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Summary & conclusions• However, we have learnt much from the early clinical studies
– The importance of recoil and speed of stent absorption– The advantage of combining with anti-proliferative drug-elution
• Future work will focus on optimising the trade-off between stent deliverability, strut thickness, and optimal drug-elution – BVS testing in more complex disease– 2nd generation REVA which is sirolimus-eluting– 2nd generation AMS with drug-elution (DREAMS)– Elixir medical device (PLA sirolimus-eluting stent)– Biocorrodible iron stents etc etc etc.......................
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