The Emerging Paradigm of Stent Biocompatibility: Current Status and Future Directions
Dr Miles DalbyConsultant CardiologistHonorary Senior LecturerRoyal Brompton & Harefield NHS TrustImperial College
Biotonik Speaker BureauConor Speaker BureauMSD Speaker BureauTranslumina Research GrantBoston Scientific Research FundingVolcano Research support
Conflicts of Interest
0.81.3
0.0
1.3 1.3
2.6
1.2
4.14.9
1.4
0
2
4
6
8
Late stentthrombosis
Thrombosis-related events
Cardiac death Non-fatal MI Death or MIEve
nts
bet
wee
n 6
-18
mo
nth
s (%
) BMS DES
0.81.3
0.0
1.3 1.3
2.6
1.2
4.14.9
1.4
0
2
4
6
8
Late stentthrombosis
Thrombosis-related events
Cardiac death Non-fatal MI Death or MIEve
nts
bet
wee
n 6
-18
mo
nth
s (%
) BMS DES
What makes a good stent…….
Acute performance: OK Anti-Restenotic Efficacy: OKSafety………………..n=????? t=?????
Evolution in Stent Biocompatibility
Coated Bare Metal Stent: Prokinetic
Drug Eluting Erodable Polymer Stent: Costar
Bioabsorbable stent: Magic
316L steel stent tube in fibrinogen solution with applied current via electrode (time wrapping 1:10)
Silicon Carbide and Thromboresistance
316LA-SiC:H
Silicon Carbide
Stainless Steel
0.5 µm
0.25 µm
0 µm
0.5 µm
0.25 µm
0 µm
Silicon Carbide and ThromboresistanceB
ioco
mpati
bili
ty
Silicon Carbide and Thromboresistance
Chandler loop
Silicon Carbide Stainless Steel
Silicon Carbide and Endothelialisation
Exposure of 316L and SiC to endothelial cells for 24h:
Light microscopy Atomic Force Microscopy
SiC
3
16L
Co-Star Paclitaxel eluting stent
Bridge Elements
Poly (lactide co-glycolide)
Bioresorbable polymer
Nanodroplet injection method Explant at 180 days
Costar architecture and apposition: OCT
Costar Stent Overlap: OCT
<100um
Costar:• Good acute performance (clinical experience and OCT)• Fully absorbable Polymer resulting in BMS• Platform for future drug release strategies
2 x 3mm 12 atm overlap no post dilatation
0
2
4
6
8
d3
0 M
AC
E (
%)
No Overlap Overlap
Costar IIBlind aggregate d30 MACE
Magnesium Alloy Bioabsorbable Stent
• Biocompatibility• Imaging• Re-Intervention• Surgery• ?Reduction in late thrombosis risk • Return of vascular function
PROGRESS AMS-1: FIM
% n % n % n
MACE 0 0 0 0 23.8 15
Death 0 0 0 0 0 0
Q-wave MI 0 0 0 0 0 0
Non Q wave MI 0 0 0 0 0 0
Ischemic Driven TLR
0 0 0 0 23.8 15
Primary Endpoint: Feasibility and safety at 4 months with MACE<30%. N=63
30-DayIn Hospital 4-Month
NegativeRemodeling /Recoil
15 Months after AMS implantation in human
IVUS OCT
Courtesy of Pr. Carlo di Mario
• Very thin neointima
• perfect ingrow of AMS
• completed healing of the stented vessel
A B
C D
Bare Metal Stent
AbsorbableMetal Stent
AMS: AMS: 16-row MSCT 16-row MSCT CompatibleCompatible
Lind et al Heart 91:1604, 2005
Stent Resorption and Vasoreactivity?
2.7
2.75
2.8
2.85
2.9
2.95
3
3.05
3.1
3.15
Pre ISDN Post ISDN
Dia
met
er (
mm
)
Pre-ISDN
Post-ISDN
Stent segment
passivatingmatrix
Mid / long term
Addition of suitable drug
Passivating coating
Short term: AMS2
The future of the AMS platformThe future of the AMS platform
Reduction ofDegradation Rate
Increase ofRadial Force
Optimization of mechanical stability
Improved Geometrical Design
ImprovedAlloy / Metallography
Inhibition ofside effects
DREAMS
Use AMS2as basic platform
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