Stent vs Scaffold
• Previously called Endovascular prosthesis
• Those which resorb completely= scaffolds
• Contemporary drug-eluting coronary
stents have better clinical outcomes
than have either bare-metal stents or first-
generation drug-eluting stents.
• But ongoing risks of stent thrombosis
and restenosis limit their long-term
safety and efficacy.
• First revolution- balloon
• Invention of balloon
angioplasty as a
for obstructive coronary
disease by Andreas
Gruntzig in 1977.
Plain Old Balloon Angioplasty
Dissections – Focal to threatened dissection
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
• 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
• 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
– Morice MC, et al. A randomized comparison of a sirolimus-
eluting stent with a standard stent for coronary revascularization.
N Engl J Med. 2002.
• The development of late adverse events
with permanent metallic stents may be
loss of normal vessel curvature,
ongoing tissue growth within the stent
• Increased risk of late and very late ST.
• late ST rates of 0.53%/y, with a continued increase to 3% over 4
– 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
– J Am Coll Cardiol. 2009
• Postmortem specimens of DES revealed significant numbers of
uncovered struts with persistent inflammation around the stent
• 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
MRI / CT compatibility (allows non-invasive follow ups)
No “Full metal jacket” makes later treatments of the same segment easier (e.g.,
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
What is the Minimum Duration of Radial Support?
Serruys PW, et al., Circulation 1988; 77: 361.
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)
The lumen appears to stabilize approximately
three months after PTCA.
p < 0.00001
p < 0.00001
Quantitative angiographic study in 342 consecutive patients at 1, 2, 3, and 4 months
While stent performance is characterized by a single
phase (Revascularization), the performance of Absorb
is governed by three distinct phases:
Together, these phases of Absorb performance deliver
What is Required of a Fully Bioresorbable
Scaffold to Fulfill the Desire for ‘Vascular
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
• 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
• Become structurally
• Allow the vessel to respond
naturally to physiological
• Resorb in a benign fashion
• The Absorb bioresorbable vascular scaffold
(Abbott Vascular) consists of a 150-μm-thick
bioresorbable poly(l-lactide) scaffold with a 7-
μmthick bioresorbable poly(d,l-lactide) coating,
which elutes everolimus.
• 100 ugm/cm2 rate of release, 80% by 28 days.
• This bioresorbable vascular scaffold has been
studied in registries and in three modest-sized
• In these trials, there was no significant
difference in the rate of adverse events
between the Absorb bioresorbable scaffold and
the Xience cobalt–chromium stent (Abbott
Vascular) within 1 year.
• However, these studies were not
adequately powered for clinical end points,
and therefore the safety and effectiveness
of the bioresorbable scaffold, as compared
with drug-eluting stents, have not yet been
A large-scale, multicenter,
randomized trial to determine the
relative safety and effectiveness of
the Absorb scaffold as compared
with the Xience stent in patients with
coronary artery disease.
• ABSORB III was a multicenter, single-
blind, active-treatment, controlled clinical
• Funded by Abbott Vascular
• Patients 18 years of age or older with myocardial
ischemia who were undergoing percutaneous
coronary intervention (PCI) for one or two new
native coronary artery lesions in separate
epicardial coronary vessels were eligible for
• Each lesion was required to be no more than 24
mm in length with a reference-vessel diameter of
2.5 to 3.75 mm on visual assessment.
• Patients with acute myocardial infarction and
specific complex lesion features were excluded.
Angiographic Exclusion Criteria
• 1. Lesion prevents complete balloon predilatation viz. Heavily calcified lesion
• 2. Anatomy proximal to or within the lesion that prevents proper passage or placement
of delivery system
Extreme angulation (≥ 90°) proximal to or within the target lesion
Excessive tortuosity (≥ two 45° angles) proximal to or within the target lesion
• 3. Lesion located within or distal to a diseased (vessel irregularity per angiogram and
> 20% stenosed lesion) arterial or saphenous vein graft.
• 4. Aorto-ostial lesion (within 3 mm of the aorta junction).
• 5. Lesion located in the left main.
• 6. Lesion located within 2 mm of the origin of the LAD or LCX.
• 7. Lesion involving a bifurcation with a:
– side branch ≥ 2 mm in diameter and/or ostial lesion ≥ 50% stenosed
– side branch requiring protection guide wire
– side branch requiring predilatation.
Angiographic Exclusion Criteria
• 8. Target vessel contains thrombus as indicated in the angiographic
• 9. Lesion involves myocardial bridge.
• 10. Target vessel was previously treated with any type of PCI (e.g.,
balloon angioplasty, sent, cutting balloon, atherectomy) < 9 months
prior to index procedure.
• 11. Non-target vessel or non-treated vessel was previously treated
with any type of PCI < 90 days prior to the index procedure.
• 12. Additional clinically significant lesion(s) (e.g., %DS > 50%) in a
target/non-target vessel or side branch for which PCI may be required
< 90 days after the index procedure.
Treatments and Randomization
• All the study patients received a loading dose of at
least 300 mg of aspirin within 24 hours before the
• A loading dose of a P2Y12 receptor antagonist was
administered before the procedure or within 1 hour
after the procedure.
• Other medications were administered according to
• Predilatation of the target lesion was required.
• After successful predilatation, patients were
randomly assigned in a 2:1 ratio to receive one of
the two study devices (the Absorb everolimus eluting
bioresorbable scaffold or the Xience everolimus-
eluting cobalt–chromium stent).
• After implantation, high-pressure
postdilatation was recommended to achieve
10% residual stenosis or less for both devices.
• Expansion of the bioresorbable scaffold to more
than 0.5 mm larger than the nominal scaffold
diameter was not permitted in order to avoid strut
• Dual antiplatelet therapy was continued for at least
1 year, and aspirin (at a dose of at least 81 mg
daily) was continued indefinitely.
• Clinical follow-up is to be performed
through 5 years and is still ongoing.
• At each follow-up visit, patients are asked
about interim clinical events, the presence
and severity of anginal symptoms, and the
use of cardiovascular medications.
• The Seattle Angina Questionnaire and
other quality-of-life instruments were used
to perform assessments at baseline, at 1
month, and at 12 months.
Study End Points
Target Lesion Failure at 1 year, powered
for non-inferiority (NI) against the
TLF is defined as the composite of cardiac
death, myocardial infarction attributable to
the target vessel (TV-MI), or ischemia-
driven target lesion revascularization (ID-
Major secondary end points were
• The 1-year rates of angina (excluding
symptoms through the time of hospital
• All revascularization,
• and ischemia-driven target-vessel
• From March 19, 2013, to April 3, 2014.
• ABSORB III and ABSORB IV cohorts
• 13,789 patients were assessed for
eligibility at 202 clinical sites in the United
States and Australia.
• Only stable patients
• Non-complex lesions
• Underpowered to assess low frequency
• Underpowered subgroup analysis
• Only 1 year follow up
TAKE HOME MESSAGES
Bioabsorbable scaffold technology is still in infancy but
developing at fast pace.
Preliminary trials have shown quite hopeful results,
especially in stable patients with non complex lesions.
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.
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
Dr. Ron Waksman MD, FACC
Associate director at Washington Hospital
Center, Washington, D.C.
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