INTERVIEW
A Polymer-free
Drug-Filled Stent
The RevElution Trial
A number of new stents have become available
to cardiologists over the last few years. At ACC.16,
CardioSource WorldNews: Interventions caught up
with Stephen Worthley, MD, professor, chair of
cardiovascular medicine, and director of the cardiac catheterization laboratory at the University of
Adelaide in Australia, about the next generation of
stent evaluated in the RevElution Study.
CSWN Interventions: Describe for us the
RevElution study and the stent.
Stephen Worthley, MD: The RevElution study
looks to be a revolution in interventional cardiology. The reason behind the name is the “elution”
part of it, which is unique. So we know that
drug-eluting stents (DES), which have become the
mainstay of a treatment of patients with coronary
artery disease, have a mechanism for delivering antiproliferative drug to the vessel to stop a
re-narrowing—restenosis—by embedding these
antiproliferative drugs in polymers.
Polymers are effectively a plastic coat that
is around the stent. When the drug has eluted
and gone away, generally speaking, the polymer
stays behind. These plastics actually induce an
inflammation, they’re an irritant, if you like, to
the vessel wall; this actually impedes the natural
healing, a growing of skin—endothelium—over
the stent. These polymers that have led to the issue
around stents not healing as quickly and, therefore,
getting clots on them or stent thrombosis.
This new stent, which we evaluated in the trial,
delivers the drug and elutes the drug with the same sort
of kinetics over the same time period as a current DES,
but does not have a polymer at all. In this unique way,
we’ve been able to core out, if you like, the internal part
of the stent so that the stent itself is not any thicker.
In fact, if anything, it’s thinner than a number of the
current stents we use. We core
out the inner part of it and put
the drug inside the stent to act as
a reservoir. We then drill tiny 20
micron diameter micro holes on
the outer surface, the abluminal
surface of the stent so that the
drug just slowly elutes onto the
vessel wall. And, therefore, allow
for the efficacy so that you don’t
see any re-narrowing—there’s
now no polymer to induce an
inflammatory response.
What else can you tell us about the study
design and patients?
So at the moment, the RevElution Study has enrolled
75 patients. It’s a single arm observational first-inhuman trial and multi-center. It includes centers
mainly in Australia, but also in Singapore and Brazil.
It is slightly complicated design in that we’ve
embedded a number of imaging time points in some
of the patients so that we can gain some insights
from optical coherence tomography (OCT)—a very
high-resolution intravascular imaging technique—
at early time points to see if that premise of early
healing is in fact seen in the imaging.
And, indeed, through the complete dataset of all of
the patients that have had 1 month OCT imaging, we
saw what we thought we would see—early healing.
We had 15 patients in that study. We saw
healing in effectively 90% of the struts. At 1 month,
we already saw an endothelial coat or covering over
the stent struts. And yet, we saw, apart from that
healing, very minimal intrusion into the vessel by
that healing process, so it was over proliferative. In
fact, the actual healing on average was a 60-micron
neointima inside the vessel.
“This new stent, which we evaluated in the trial,
delivers the drug and elutes the drug with the
same sort of kinetics over the same time period as
a current DES, but does not have a polymer at all.”
32
CardioSource WorldNews: Interventions
CardioSource WorldNews Executive Editor Rick McGuire interviews
Stephen Worthley, MD, at ACC.16 in Chicago.
OCT has sometimes delivered surprising images of
the bioabsorbable stents—
it was a very big surprise
and researchers weren’t
really predicting it. In this
case, you’re seeing exactly
what you wanted to see.
To watch the fill
interview with
Stephen Worthley,
MD, visit the CSWN
YouTube channel or
scan the QR code
below. Interview
conducted by Rick
McGuire.
It’s what we hoped to
see, exactly right. You
never know until you do
the trial, but it basically
what we’d seen in that
early preclinical work that
indeed, we’d seen an early
healing at 1 month. We’ve
seen very low neointimal
proliferation. We’ve seen
very little malapposition,
meaning where the stent
itself is now is not adherent to the vessel wall. So
it’s a malapposed strut—1.5%, which is actually
very low because, in normal clinical practice,
we’d expect somewhere between a 3% to 7%
malapposed struts.
It’s 1-month data, but it’s the complete 1-month
dataset on the OCT sub-study and it’s very exciting. ■
Editor’s note: This interview was edited from transcript.
September/October 2016