Biovascular scaffolds - current status 2015

BIOVASCULAR SCAFFOLDS –
CURRENT STATUS
Dr. ANSHUL KUMAR GUPTA
Seminar
11.06.2015

OVERVIEW
 History & evolution of BVS
 Physiology of BVS
 Advantages
 Types of BVS
 Clinical trials
 Future perspectives

• First revolution- balloon
angioplasty
• Invention of balloon
angioplasty as a
percutaneous treatment
for obstructive coronary
disease by Andreas
Gruntzig in 1977.

Plain Old Balloon Angioplasty
(POBA)
 Dissections – Focal to threatened dissection
 Acute recoil
 Chronic constrictive remodeling

• Second revolution – BMS
• The advent of BMS and the landmark Belgian-Netherlands Stent
Study (BENESTENT) and Stent Restenosis Study (STRESS) trials
have established BMS as the second revolution in interventional
cardiology.
• A solution to acute vessel occlusion by
– sealing the dissection flaps
– preventing recoil
– making emergency bypass surgery a rare occurrence.
– Serruys et al.A comparison of balloon-expandable-stent implantation with
balloon angioplasty in patients with coronary artery disease: Benestent Study
Group. N Engl J Med. 1994;331:489–495.

Plain Old Balloon
Angioplasty(POB
A)
Bare Metal
Stent(BMS)

• Third revolution - DES
• The first 45 patients implanted with the sirolimus
eluting Bx velocity stent (Cordis, Johnson &
Johnson) were found to have negligible neointimal
hyperplasia at follow-up.
• This was confirmed in the randomized comparison of
sirolimus-eluting stent with a standard stent for
coronary revascularization (RAVEL) study.
– Morice MC, et al. A randomized comparison of a sirolimus-eluting
stent with a standard stent for coronary revascularization. N Engl J
Med. 2002.

• Disadvantages
• Increased risk of late and very late ST.
• late ST rates of 0.53%/y, with a continued increase to 3% over 4
years.
– Late thrombosis in DES after discontinuation of antiplatelet therapy.
Lancet. 2004
• In the (ARTS II) trial, the rate of combined definite, probable, and
possible ST was as high as 9.4% at 5 years, accounting for 32% of
MACE.
– J Am Coll Cardiol. 2009
–
• Postmortem specimens of DES revealed significant numbers of
uncovered struts with persistent inflammation around the stent
struts.
• Vasomotion testing demonstrated vasoconstriction to Ach.
– Vascular responses to drug eluting stents: importance of delayed

• Fully Bioresorbable Scaffold: The Fourth
Revolution in Interventional Cardiology?

Why Bioabsorbable stents??
Potentially: no late stent thrombosis and no need for prolonged antiplatelet
therapy
MRI / CT compatibility (allows non-invasive follow ups)
No “Full metal jacket” makes later treatments of the same segment easier (e.g.,
surgical bypass)
Leaves no stent behind long-term (no chronic inflammation, no long-term impact
on local vasomotion)
Provides stent scaffolding and radial strength properties as long as needed to
ensure an open lumen – same as permanent stent

• On Premise that scaffolding & drug are only required on a
temporary basis following coronary interventions.
• Several studies support this concept and indicate that there is no
incremental clinical benefit of a permanent implant over time.
• Use of Absorbable scaffold eliminates the presence of a mechanical
restraint and offers potential of restoring natural vessel reactivity.
– Incidence of restenosis after successful coronary angioplasty: a time-related
phenomenon. A quantitative angiographic study in 342 consecutive patients at 1,
2, 3, and 4 months. Circulation, 1988.
Vascular Reparative therapy

 While stent performance is characterized by a single
phase (Revascularization), the performance of Absorb is
governed by three distinct phases:
 Revascularization
 Restoration
 Resorption.
 Together, these phases of Absorb performance deliver
VRT

What is Required of a Fully Bioresorbable
Scaffold to Fulfill the Desire for ‘Vascular
Restoration Therapy’?
Revascularization Restoration Resorption
0 to 3 months 3 to ~6-9 months + ~9 months +
Performance should mimic
that of a standard DES
Transition from scaffolding
to discontinuous structure
Implant is discontinuous
and inert
• Good deliverability
• Minimum of acute recoil
• High acute radial strength
• Controlled delivery of drug
to abluminal tissue
• Excellent conformability
• Gradually lose radial strength
• Struts must be incorporated
into the vessel wall (strut
coverage)
• Become structurally
discontinuous
• Allow the vessel to respond
naturally to physiological
stimuli
• Resorb in a benign fashion

What is Required of a Fully Bioresorbable Scaffold to Fulfill the
Desire for ‘Vascular Restoration Therapy’?
1 3 6 2 Yrs
Full Mass Loss &
Bioresorption
Mos
Platelet Deposition
Leukocyte Recruitment
SMC Proliferation and Migration
Matrix Deposition
Re-endothelialization
Vascular Function
Forrester JS, et al., J. Am. Coll. Cardiol. 1991; 17: 758.
Revascularization Restoration Resorption
Everolimus Elution
Mass Loss
Support
Oberhauser JP, et al., EuroIntervention Suppl. 2009; 5: F15-F22.

• Vessel Remodeling
• Through the use of the imaging modality
intravascular ultrasound (IVUS), data from the
ABSORB Cohort B trial, reveals an increase in
lumen area between 6 months and 2 years.
• As Absorb resorbs, the vessel segment becomes
unconstrained and there is the potential for lumen
gain.

• Vasomotion
• As Absorb resorbs, the treated vessel segment is able to react
to changes in blood flow and physiological stimuli that may
occur with exercise or certain drugs.
• By no longer supporting or caging the vessel, there is the
potential for allowing the vessel to respond naturally to
physiological stimuli, which could provide unique benefits.

MECHANICAL CONDITIONING IN PRE-CLINICAL
MODEL (PORCINE)
Tests were performed by and data are on file at Abbott Vascular.
Transmission Electron Microscopy (TEM) Smooth Muscle -Actin
Dense
bodies
At 36 months, SMCs are well organized and have undergone
transformation to a functional, contractile phenotype
Mechanical
conditioning

 First absorbable stent implanted in
humans
 Constructed from PLLA.
 Hydrolysis of bonds between
repeating lactide units produces
lactic acid that enters the Krebs
cycle
 first-in-man prospective,
nonrandomized trial that enrolled
50 pts
 4yr follow-up of all pts revealed a
low complication rate.
 loss index (late loss/acute gain)
was 0.48 mm, which was
comparable to BMS
Tamai H, Igaki K, et al. Circulation
2000
IGAKI – TAMAI Bioabsorbable STENT

• Despite impressive initial results, failure of the stent to
progress was related primarily to the use of heat to
induce self-expansion.
• Concerns - could cause necrosis of the arterial wall,
leading to excessive intimal hyperplasia or increased
platelet adhesion, leading to ST.
• Biodegradable peripheral Igaki-Tamai stents PERSEUS
study, the stent became available in Europe for
peripheral use.
– Biamino G, Schmidt A, Scheinert D. Treatment of SFA lesions with
PLLA biodegradable stents: results of the PERSEUS Study. J Endovasc
Ther. 2005;12:5.

Igaki Tamai – 10 yr follow up (n=50)
Kaplan-Meier curves showing:-
(A)survival rates free of cardiac death
(B) Death
(C) major cardiac adverse events.
Cumulative rates of :-
target lesion revascularization (TLR)
target vessel revascularization (TVR)
Circulation 2012.

Biotronik Absorbable Metal STENT
(AMS)

• Prolonged mechanical stability, different Mg alloy
with a higher collapse pressure and slower
degradation time.
• Modified stent surface - strut thickness reduced
• Shape of the strut changed from rectangular to
square (improving radial strength).
• Prolonged scaffolding and stent integrity, improved
radial strength, and reduced neointimal proliferation
in animal models.
AMS – 2 STENT

• The AMS-3 stent (drug-eluting AMS) is
designed to reduce neointimal hyperplasia
by incorporating a bioresorbable matrix for
controlled release of an antiproliferative drug
onto the AMS-2 stent.
• Research is currently focused on
establishing the ideal drug kinetics; initial
animal trials have demonstrated a sustained
antiproliferative effect at 1 month.
AMS - 3 STENT

 The degradation of Mg produces an
electronegative charge that results in
the stent being hypothrombogenic.
PROGRESS AMS trial: Lancet. 2007;369:1869 –1875.
 PROGRESS AMS was a non randomized, prospective study in 63 pts.
 Stent was completely absorbed within 2 mths, radial support was lost much
earlier  there was an insufficient radial strength to counter the early negative
remodeling forces after PCI.
 In addition, it did not release an antiproliferative drug to counter the intimal
hyperplastic response to stenting.
 High restenosis rate at 4 months of almost 50% and target vessel
revascularization at 1 year was 45%. MACE rate 26.7% at one yr.
Magnesium
Bioabsorbable STENTs

Stent:
Bioabsorbable
Magnesium Alloy
Discrete Drug
Delivery Reservoirs
Drug:
Pimecrolimus
Carrier:
Bioresorbable
Matrix
Modifications
Biotronik DREAMS
(Pimecrolimus – Eluting stent system)
BIOSOLVE II TRIAL is ongoing with DREAMS 2nd gen drug eluting AMS.

REVA Medical – Stent features

RESORB Study
 (REVA Endovascular Study of a Bioresorbable Coronary
Stent) trial enrolled 30 pts at multiple sites in Germany and
Brazil
 Non-randomized study
 Endpoints
• Primary – 30 days MACE
• Secondary – 6 mths QCA & IVUS derived parameters for
restenosis.
 Clinical follow up
• At discharge, 2 wks, 1, 6, 12, 24, 36, 48, 60 months.
• Subset of pts will be returning for long term angiographic
follow up.

 6 mths follow up showed absence of any significant vessel
recoil.
 Unfortunately higher-than-anticipated rate of TLR (66.7%)
were seen between 4 and 6 months.
 The degree of neointimal hyperplasia was similar to that of
a BMS
 Redesigning of the stent ensued, resulting in the
second-generation ReZolve stent.

• More robust polymer, a spiral slide-and-lock mechanism to improve
clinical performance, and a coating of sirolimus (80% is eluted by 30
days and 95% by 90 days.)
• The RESTORE Trial evaluating the safety and performance of the
1st-generation ReZolve scaffold in 26 pts.
• One yr follow up showed late lumen loss comparable to that of DES.
• The ReZolve2 scaffold, a lower profile and sheathless version of
the original ReZolve scaffold evaluated clinically in the RESTORE II
TriaL (started in 2013)
ReZolve stent

Poly (Anhydride ester) Salicylic acid : the
IDEAL stent

• IDEAL stent is radio-opaque and salicylate acts as anti-
inflammatory agent.
• Whisper trial, a stent with strut thickness of 200 µm and
a crossing profile of 2.0 mm with a stent-to-artery
coverage of 65% was implanted in 8 patients.
• Because of higher-than-expected intimal hyperplasia, a
subsequent design iteration will have thinner struts, a
higher dose of sirolimus, and a lower percent wall
coverage.

 Crossing profile of 1.4 mm with circumferential hoops of PLLA.
 The struts are 150 µm thick and are either directly joined or linked by
straight bridges.
 Both ends of the stent have 2 adjacent radiopaque platinum markers.
radial strength = BMS.
 The backbone of the BVS device is made of semicrystalline polymer
called PLLA.
 Coating of poly D,L-lactide acid (PDLLA).
 Coating contains and controls the release of everolimus.
Everolimus-Eluting PLLA Stent: BVS Scaffold

BIORESORBABLE POLYMER
Everolimus/PDLLA Matrix
Coating
• Thin coating layer
• Amorphous (non-crystalline)
• 1:1 ratio of Everolimus/PLA
matrix
• Conformal Coating, 2-4 m
thick
• Controlled drug release
PLLA Scaffold
• Highly crystalline
• Provides device integrity
• Processed for increased radial
strength
Polymer backbone
Drug/polymer matrix

Lancet 2008; 371: 899–907
ABSORB cohort A study

 Prospective, open-labeled, non-randomized, multi-center trial.
 First in Man ABSORB stent
 First clinical evaluation of the safety and performance of the BVS
Cohort A device. (n=30)
 Among 29 patients, the 5-year MACE rate was low at 3.4%, due to
only one ischemic MACE event (non-Q wave MI.) that was reported
within the first 6 months of the trial.
 There were no incidences of (ID-TLR)
 No incidences of scaffold thrombosis or cardiac death out to 5 years

• N = 30; 6 sites (Europe, New Zealand)
• Clinical follow-up schedule:
– 30 days, 6 months, 12 months, annually to 5 years
• Imaging schedule:
QCA, IVUS, OCT, IVUS VH Baseline
6 18 24
MonthsMonthsMonths
MSCT
(optional)

 Procedural success was 100% (30/30 pts)
 Device success 94% (29/31 attempts)
 At 1 year, MACE rate 3·3% (one pt having a non-Q wave MI and
no TLR.
 No late stent thromboses.
 At 6mths, angiographic in-stent late loss was 0·44 (0·35) mm and
was mainly due to a mild reduction of the stent area (–11·8%) as
measured by IVUS.
ABSORB cohort A study – 1yr Results

Lancet 2009; 373: 897–910
ABSORB cohort A study – 2 years follow up

At 2 years:-
 Stent was bioabsorbed
 Vasomotion restored
 Restenosis prevented
 Clinically safe, freedom from late thrombosis
 Late luminal enlargement due to plaque reduction without vessel
remodelling.
ABSORB cohort A study – 2 years results

HPE in a preclinical porcine study

J Am Coll Cardiol Intv 2013;6:999–1009
ABSORB cohort A study – 5 years results

ABSORB cohort A – 5 year clinical results
J Am Coll Cardiol Intv 2013;6:999–1009

Cohort A
Cohort B
• More uniform strut distribution
• More even support of arterial wall
• Lower late scaffold area loss
― Maintain radial strength for at least 3 months
• Storage at room temperature
• Improved device retention
• Unchanged:
– Material, coating and backbone
– Strut thickness
– Drug release profile
– Total degradation Time
• More uniform strut distribution
• More even support of arterial wall
• Lower late scaffold area loss
―Maintain radial strength for at
least 3 months
• Storage at room temperature
• Unchanged:
– Material, coating and backbone
– Strut thickness
– Drug release profile
– Total degradation Time
BVS Device optimization

J Am Coll Cardiol 2011;58:1578–88)
ABSORB Cohort B study

• ABSORB Cohort B trial had two subgroups (B1 and B2) for follow-up
purposes as determined by protocol.
• 3-year follow-up data for Group B1 (n=45) was reported at the TCT
2012 meeting in Miami, Florida, USA
• Among 100 patients, there has been no reported scaffold
thrombosis or cardiac death.
• 2-year ischemic driven MACE rate was 9.0%, due to 3 non-Q wave
MIs and 6 ischemia driven TLR.

ABSORB B1&2 study results
No scaffold thrombosis

ABSORB Cohort B1 study results
No new MACE between 6 mths to 3 yrs.

 Clinical Procedure Success 98%
 ABSORB B Group 1 –MACE rate of 6.8% at 2 and 3 years (1 peri-
procedural MI & 2 TLR)
 No additional MACE between 1 yr and 3 yrs
 No scaffold thrombosis event.
 Clinical data very comparable to Xience-V data from SPIRIT I+II+III.
Conclusion Absorb B study

MACE rates in ABSORB cohort B vs
XIENCE V (SPIRIT I+II+III Study)

 The ABSORB EXTEND trial is a continuation in the assessment of
the safety and performance of Absorb in a larger study.
 The lesions are longer than in the ABSORB Cohort A and Cohort B
trials.
 Planned overlap of Absorb scaffolds during the procedure
 ABSORB EXTEND is a prospective, single-arm, open-label clinical
study in 1,000 subjects at 100 global sites.
 Clinical follow-up for up to 3 years.
ABSORB EXTEND Study

Conclusions from 6 mths data
6 months follow up data showed:-
 Low event rates including MACE (3.0%) and Stent thrombosis
(0.6%)
 MACE rate shown at 6 months were sustained with the first 250
pts enrolled through 12 mths follow up
 Data from ABSORB EXTEND demonstrated the consistency in
clinical outcomes between ABSORB EXTEND, ABSORB Cohort
B and the SPIRIT pooled population.

ABSORB EXTEND/Cohort B MACE
(Through 12 mths)

ABSORB EXTEND/SPIRIT MACE
(Through 12 mths)

ABSORB EXTEND/SPIRIT ID-TLR
(Through 12 mths)

ABSORB EXTEND/SPIRIT Stent thrombosis
(Through 12 mths)

ABSORB EXTEND – Diabetic subgroup
6 mths clinical outcomes (n = 500)

Follow up of 250 pts at 12 months showed:-
Results comparing ABSORB EXTEND and Cohort B patient
demographics and lesion characteristics:
 Over twice the percent of UA (35.2% in EXTEND vs 14.9% in
Cohort B)
 Higher percentage of diabetics (24.8% in EXTEND vs 16.8% in
Cohort B)
 Longer mean lesion length than in ABSORB Cohort B
 Planned overlapping treatment permitted (6.4% of pts)
Findings on the 12 mths outcomes in 250 pts:-
 Comparable MACE rates to ABSORD Cohort B and SPIRIT Pooled
population
 Lower rate of ID-TLR (2.0%) in EXTEND compared to Cohort B
and SPIRIT Pooled population.
ABSORB EXTEND – conclusion from 12mths
data

 ABSORB II is a randomized, active-controlled, single-blinded,
multicenter clinical trial and will enroll approximately 501 subjects in
40 sites in Europe.
 Aim: primary endpoints of vasomotion and change in lumen
diameter.
 Subjects were clinically followed at 30 days, 180 days, 1, 2, and 3
years post-procedure
 Imaging studies included angiography, IVUS/IVUS-virtual histology,
MSCT, all at 2 yrs and 3 yrs.
ABSORB II: European RCT

ABSORB II one year analysis was presented in TCT 2014
and published in Lancet September 2014 issue.
ABSORB II

Summary
 Device success rates were comparable (100% vs 99%)
 Acute gain by angiography and IVUS was significantly
lower in Absorb arm than Xience arm.
 Difference in acute gain was not related to acute recoil
measured immediately after device implantation (0.19
mm for both) but could be attributed to the difference in
pressure and nominal size of the balloon used during
post-dilation performed in similar proportions (~60%) in
each arm.

 Two definite scaffold thromboses were documented – one
acutely within 24 hrs and second subacutely on day 2.
 The rate of definite stent thrombosis was 0.6% in the
Absorb arm and 0% in Xience arm (p=1.0)
 At one year Device related composite end points DoCE
(cardiac death, TV-MI, and TLR, Absorb: 4.8% vs Xience:
3.0%, p = 0.35) and patient related composite end points
PoCE (all deaths, all MI and all revascularization, Absorb:
7.3% vs Xience: 9.1% p= 0.47) and their components were
similar between the two arms.

 The ABSORB (RCT) is designed to evaluate the clinical safety and
efficacy of Absorb for US approval in comparison with the
XIENCE family.
 The ABSORB III is a prospective, randomized, active-control, single-
blind, multi-center clinical trial that will register approximately 2,250
subjects in up to 220 sites in the US and outside the US.
 Cohort of approx 2,000 pts will be used for approval of Absorb by
the US - FDA.
ABSORB III: US RCT for US approval

 The ABSORB IV trial is similar in design to ABSORB III, and
designed to enroll approximately 2,500 to 3,000 patients with clinical
follow-up out to 5 years.
 Clinical data from both ABSORB III and IV will be pooled to enable a
landmark analysis for 4,500 to 5,000 subjects to show superior
safety and benefits of Absorb compared to XIENCE.
ABSORB IV: RCT for Landmark analysis

 ABSORB Japan is a prospective, single-blind, multi-center
randomized 2:1 trial of Absorb: XIENCE V involving up to 400
subjects in up to 35 Japanese sites to seek Japanese approval.
 The patient eligibility criteria are similar to the ABSORB III study.
 The primary endpoint is 1 year target lesion failure (TLF) showing
non-inferiority to XIENCE, with each subject returning for at least
one imaging follow-up involving one of the following modalities:
angiography, IVUS, and/or OCT.
ABSORB Japan: RCT

 ABSORB China is a prospective, single-blind, multi-center
randomized 1:1 trial of Absorb: XIENCE V involving approximately
400 subjects in up to 25 Chinese sites.
 The patient eligibility criteria are similar to ABSORB III.
 The primary endpoint is 9 months angiographic endpoint of in-
segment late loss, showing non-inferiority to XIENCE, for Chinese
approval.
 Patients will subsequently return only for clinical follow-up out to 5
years.
ABSORB China: RCT

• The ABSORB FIRST Registry is designed to evaluate the safety
and clinical outcomes of Absorb in daily use in patients with de
novo lesions in previously untreated vessels.
• Single arm, prospective, international post-market registry of
patients with de novo lesions in previously untreated vessels treated
with Absorb per IFU (on-label use).
• Enrolling min of 10,000 pts in approx 300 sites throughout multiple
countries worldwide where Absorb has regulatory approval and is
commercially available.
• One yr follow-up will be conducted on all pts. Annual follow-up visits
will be conducted in subgroups of 1,000 patients each from 2 to 4
years.
ABSORB FIRST: International Post-
Market Registry

N=100
Cohort 1 – 46 pts with UA
Cohort 2 – 38 pts with NSTEMI
Cohort 3 – 16 pts with STEMI

• First, the optimal duration of scaffolding with drug-
elution should be further elucidated.
• In both AMS-1 magnesium stent and BVS 1.0 scaffolds, late scaffold
shrinkage was one of major contributors to luminal loss.
• In a previous study with serial IVUS imaging after angioplasty or
directional coronary atherectomy, some positive remodeling
occurred early after the procedure up to 1 month, whereas the
negative remodeling occurred at 1 to 6 months
Future Perspectives

 This suggests that the need to prevent negative remodeling is
necessary at least until 6 months.
 This could be achieved by tuning the biodegradation speed in
changing the molecular weight of the polymer and increasing its
crystallinity, thereby prolonging the mechanical integrity of the
scaffold.

2. BRS technologies without drug elution such as REVA
and AMS-1 were associated with high TLR rates.
 In AMS-1 trial, 45% of late luminal reduction was attributed to
neointimal hyperplasia at 6 mths.
 These results suggest that the elution of antiproliferative agents might
be indispensable to make the BRS clinically applicable and efficient at
medium term.

3. The clinical advantage of BRS technology over the
currently available DES needs to be further
investigated.
 BVS and Mg stents showed the recovery of responsiveness of the
treated vessel to vasoactive agents such as nitroglycerin.
 Restoration of vasomotion can indirectly stand for the completeness
of vessel healing; however, it is still unclear what the real clinical
advantage of this phenomenon is.

4. A potential drawback of this new technology is strut
fracture.
 Unlike metallic stents, the polymeric devices have inherent limit of
expansion and can break as a result of overdilatation.
 In an anecdotal case from the ABSORB cohort A, a 3.0-mm scaffold
was overexpanded with 3.5-mm balloon, which resulted in strut
fracture as documented with OCT.
 The clinical significance of such a case, evidenced only by OCT,
needs to be further elucidated, but undoubtedly fracture should be
avoided by respecting the nominal size of the scaffold.

5. Data transferability might be another issue from the regulatory
perspective.
 In conventional metallic stents, the essential component was
platform, coating, and drug.
 In BRS polymeric stents, even with the same PLLA and design, the
speed of bioresorption can be different according to the
manufacturing process of PLLA.
 Molecular weight of the polymer can influence the degree of
inflammation.

 Absence of large RCTs
 Experience in complex cases (bifurcation, ostial, CTO) is limited
and in such cases IVUS should support BVS implantation.
 High strut thickness may lead to vessel injury, nonlaminar flow,
platelet deposition, and poor deliverability.
 Calcification or tortuosity are technically challenging.
 Regardless of lesion anatomy, pre-dilation is mandatory, direct
stenting is not possible.
 Predilatation makes the system prone for dissection and
ischemia
Current limitations and challenges

 Only limited scaffold sizes are currently available, and special
facilities are needed for storage of some.
 Due to these technical particularities, the total cost and duration of
PCI with a BRS may be higher than with a conventional DES.
 Duration of DAPT with BRS is unclear.
Current limitations of BVS contd…

 Current BRS limitations will likely be resolved in the
future.
 Although their advantages already outnumber their
disadvantages, large, randomized, controlled trials are
still needed.
 Although promising in certain conditions but more
randomised trials and technology advance is required to
implement them in a wider perspective.
Future perspectives

Conclusions
 Bioabsorbable scaffold technology is still in infancy but
developing at fast pace.
 Preliminary trials have shown quite hopeful results
 Larger randomized trials are ongoing and their results
will dictate the future of this novel technology.
 Although promising in certain conditions at present but
more randomised trials and technology advance is
required to implement them in a wider perspective.

117
THANK YOU …
“In 10 years, we may look back and laugh
at the time when we used to leave behind
little pieces of metal in
patients’ vessels,”
Dr. Ron Waksman MD, FACC
Associate director at Washington Hospital
Center, Washington, D.C.

Characteristics of an ideal Bioabsorbable stent
 Predictable degradation rate over a finite period of time
 Should leave no residue
 Degradation products should be biocompatible, non-toxic and non-
inflammatory
 Stent material should have high tensile strength to allow creation of
low profile, balloon expandable stent
 Material should have adequate radial strength and mechanical
properties for vessel support
 Non-thrombogenic  should not shed emboli
 Material should be easily processed and sterilizable
 Acceptable shelf life

Ideal characteristics of bioabsorbable polymer
 Linear degradation profile
 Fast degradation rate (< 6months)
 Compatibility with hydrophilic and hydrophobic drugs
 Stable under different pH
 Good film forming properties
 Solubility in common solvents
 No toxic metabolic end products

Biovascular scaffolds - current status 2015

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