Oct 24, 2016
Carolyn:
Welcome to Circulation on the Run, your weekly podcast summary and
backstage pass to the journal and its editors. I'm Dr. Carolyn Lam,
associate editor from the National Heart Center and Duke National
University of Singapore. We have such a special podcast for you
today. The entire podcast is going to be a conversation with two
very special guests, Dr. Marc Ruel from The University of Ottawa
Heart Institute, the guest editor of the surgery themed issue this
week. Hi Marc.
Marc:
Hello Carolyn. How are you?
Carolyn:
Very good. Especially because we also have Dr. Timothy Gardner,
Surgeon, Associate Editor from Christiana Care Health System.
Welcome back again, Tim.
Timothy:
Thank you, Carolyn. Glad to be here.
Carolyn:
Marc, could you first give us an overview of the surgery themed
issue from your perspective.
Marc:
This year as we have had on previous years, we are having a surgery
themed issue which comprises what I would argue which is some of
the very best cardiac surgical science can offer to the wide
readership in the cardiovascular community that served by
circulation. This year, we will have a total of ten articles that
would be published in circulation, as a section of one of our
regular issues and out of those ten, there are five original
papers. There's one research letter which is an original research
article but in a shorter format and we'll also have one invited
perspective paper namely about coronary artery bypass grafting and
its future with respect to multi-arterial grafts and the themed
issue will be completed by three state of the art papers that deal
in a very in depth comprehensive way with some important problems
that the cardiovascular community faces from a clinical point of
view.
Carolyn:
Thanks Marc. That was a beautiful summary of the issue. I couldn't
help but notice that there was a theme of coronary artery bypass
surgery covering at least four of the papers and I really like your
thoughts on that. You covered everything from medical therapy, CABG
versus PCI, on versus off-pump, emergency surgery in the setting of
shock. Could you go through each of these four papers a little and
tell us what was your take home message from each?
Marc:
As you said, there are three original research articles and one
invited perspective that relate to coronary artery bypass grafting
surgery and these encompass the number of clinical problems that
are still controversial and certainly I believe they contribute a
very, very significant [inaudible 00:02:31] with the wealth of
knowledge that the cardiovascular community is looking for at this
point. If I may go one by one, just with a very high level
overview, if you will. The first one is a paper from the Leipzig
Heart Center with first author, [Pieroz Adewalla 00:02:45], which
looked at surgery for acute myocardial infarction but accompanied
with cardiogenic shock. As you know, many patients undergo surgery
in an acute MI context, but surgery for cardiogenic shock is often
a very gruesome difficult decision.
Leipzig Heart Center looked at over 3,000 patients who had an acute
MI prior to cardiac surgery for bypass surgery and of these, there
were 508 patients who actually had cardiogenic shock due to [valve
00:03:15] failure with myocardial dysfunction and to give you an
idea, these patients were quite sick. There's about 40% of the
patients who were ventilated prior to surgery or very close to 40%.
The timing was quite urgent, those patients were on inotrophes and
on vasopressors to support their blood pressure prior to operation.
Essentially, what they found is that first the outcomes got better
over the last number of years, this is a series that dates back to
about the 2000's, so the early 2000's.
They also favor an approach where they tried to avoid a
cardioplegic arrest of the heart. Their favored overall approach is
to do what we call on-pump beating heart type of surgery which
would be a surgery where the cardioplegia would not be administered
to stop the heart but the hemodynamics would be supported for the
cardio coronary bypass. They also have over the years since the
beginning of this year, is in 2000 ranging up to 2014 of increasing
the use of the off-pump bypass surgery and certainly the outcomes
have been better and the mortality although high has decreased
significantly. It was as high as 40% in the early parts of the
cohort if you will and in the latest third of the experience,
therefore from 2010 to 2014, the mortality has been down to about
25%.
Again, these are patients who present with cardiogenic shock.
What's also interesting to note is that patients who survive out of
hospital still have a significant mortality burden and about 50% of
them survive long term. What was interesting is the Leipzig
group is looking at some predictors of bad outcomes in those
patients and they found that the serum lactate over four minimal
per liter was actually a very robust and multi-variative predictor
of a poor outcome after surgery.
Carolyn:
That was a great summary of that first paper. You mentioned beating
heart surgery and so on. Would you like to comment on next paper
that I think was the largest single institution European study
comparing on versus off-pump bypass surgery?
Marc:
You're absolutely right. This is a paper from England, [inaudible
00:05:25] from Liverpool, where the patients were gathered from and
with some contribution from Oxford as well from a statistical and
methodological point of view and it's a retrospective cohort study
of all isolated CABG patients in Liverpool between 2001 and 2015.
These are bypass surgery patients and in total, there were over
13,000 patients who had CABG. About 6,000 patients had off CAB
which is off-pump bypass surgery and more than 7,000 had bypass
with cardiopulmonary bypass. The median follow up was 6.2 years.
What's interesting in this paper is that they essentially found
equivalent long term outcomes. As you know, there has been some
debate regarding the completions of myocardial revascularization
and the long term graft patency with off-pump surgery versus
on-pump surgery. Also named conventional CABG.
What's interesting here is that the benefits of off-pump CABG
appear to be seen early on with regards to antiemetic release as
stroke rates, etc. Which does correspond to some of what has seen
in the randomized controlled studies. However, the long term data
is interesting. There's a a nice editorial about this paper written
from a group from the Cleveland Clinic with Dr. Joe Sabik as the
senior author and essentially it raised a number of good points,
although this is an important series, it also shows that the
surgeons who are very good at off-pump bypass surgery may overall
be slightly technically more skilled at doing bypass surgery in
itself and for instance, use more often arterial grafts and have
more advanced techniques in their completion of bypass surgeries
for their patients.
Carolyn:
Right. I'm so glad you mentioned the editorial. I was about to
bring that up as well. Switching gears to you very kindly included
a paper that talked about medications and the impact of here is the
medical therapy on the comparative outcomes between CABG and PCI.
Would you like to discuss that paper?
Marc:
This is a paper from the Care Registry which has generated some
interesting publications in the past. The lead author is Dr. Paul
Polinski and there's co-authors, Dr. Herbert Prince and Michael
Mack from Dallas as well. This was presented at the science
sessions in Orlando last November and it's an interesting paper.
Essentially they have looked at large databases, again the Care
Registry which comprises eight community hospitals and they look at
six month period of performance of CABG and those eight community
hospitals. They ended up with over 2,700 patients who were then
systematically followed on a regular basis up to 2009 at which time
the database was locked.
They look at various outcomes but also medication use in great
detail over that period of time and the interesting perspective
that this paper brings is that first, most patients at least in
that period were not on optimal medical therapy. The authors used
their own predefined definitions of what constitutes optimal
medical therapy and this is with regards to adherence to aspirin
use, lipid lowering agents, beta blockers and indicates of PCI,
dual anti-platelet therapy. As expected but nicely documented in
this paper, the outcomes of patients who were not on optimal
medical therapy were much worse than those who were and CABG proved
to be more robust in patients who were not on optimal medical
therapy compared to PCI.
The differences between CABG and PCI in patients who were on
optimal medical therapy tended to vanish. However, a number of
caveats here is that only 25% of patients in fact in this cohort
were on optimal medical therapy. The vast majority of patients were
not considered to be on optimal medical therapy. Therefore, there
are considerations of definitions that one has to be aware of and
also considerations of statistical power because the group that was
on optimal medical therapy was much smaller than the other group.
Therefore, the effects, the superiority of CABG over PCI could only
be firmly demonstrated in the group was not on optimal therapy,
again comprising 75% of patients in this cohort.
Carolyn:
I love your summaries and they really show that these are true
significant original contributions to that knowledge gaps in
coronary artery bypass surgery. To round it all up, you also
invited a perspective on novel concepts. Would you like to comment
on that paper?
Marc:
This is an invited perspective in the view classifications that
circulation has which is entitled, "The evolution of coronary
bypass surgery will determine relevance as a standard of care for
the treatment of multi-vessel CABG." It is authored by three
leaders in the field, Dr. Gener, Dr. Gudino, and Dr. Grouw. Dr.
Gener has been leading several of what I would call the advanced
multi-vessel coronary re-vascularization trials looking for
instance at multi-arterial grafts doing numerous anastomosis with
two ventral mammary arteries in a wide fashion. He's been a leader
of this movement certainly. Dr. Gudino recently published
[inaudible 00:10:43] the 20 years of outcome of the radial artery
graft and certainly has been one of the pioneers which use of this
arterial graft for coronary artery bypass surgery. What the authors
provide here is a very nice summary of what the trials have shown
so far and they also report as many know that their rate of
multi-arterial grafts use in SYNTAX, FREEDOM and I think we will
soon see in EXCEL and NOBLE that will be presented this fall, has
not been as high as it should have been.
In the US, it is estimated right now that the rate of use of more
than one mammary artery is less than 10% across the nation, and
other countries have not performed better than this either. This
perspective is a call to improving the quality of multi-vessel
coronary artery bypass mainly through the use of multiple arterial
re-vascularization. There is also considerations around the hybrid
coronary re-vascularization and as well as the use of off-pump
versus on-pump surgery.
Carolyn:
I am really proud and privileged to have helped to manage one of
the papers as associate editors in this issue as well and that is
the paper from the group with corresponding author, Dr. Veselik,
from Boston Children's Hospital and it centers around patients with
congenitally corrected transposition of the great arteries but a
management problem that is really increasingly encountered and
really needs to be reviewed properly and that is the management of
systemic right ventricular failure in these patients. Tim, you were
so helpful in looking at this paper as well. Could you share some
of your thoughts?
Timothy:
Well, this is a somewhat unique situation where a patient with this
condition, congenitally corrected transposition of the great
arteries may go through early life, in fact may end up as a young
adult before this particular condition is identified because if
there is no shunting or no cause for cyanosis and heart murmurs and
so on early on, the circulations seem to work pretty well until the
poorly prepared right ventricle which is the systemic ventricle,
starts to fail after years of work carrying the systemic
circulation and that is really the focus of the paper. There's been
a lot of work and publications and attention to transposition
syndromes but this particular one is a condition that may be first
encountered by adult heart failure cardiologist who have not had
this kind of exposure to congenital heart disease. It's a
particularly apt paper to bring this condition to our attention and
to demonstrate that really it's the adult heart failure
cardiologist who may be managing these patients in their late 20's
or 30's, when that systemic right ventricle fails because of a lack
of formation to manage the systemic circulation.
Carolyn:
Exactly. Written by a group that has one of the most robust
experiences in this field, so that also brings to mind another
state of the art article in the issue that refers to the
hypoplastic left heart syndrome and though it's entitled that and
people may think it's rare, I think it's increasingly being seen in
the adult cardiology world as well. You want to comment on that
one?
Timothy:
That actually is one of the main points of this paper that this
very, very difficult condition of hypoplastic left heart syndrome
that requires staged operations beginning in the neonatal period
has now reached the state of surgical accomplishment in medical
management where many of these young children are surviving into
young adulthood. Albeit, with having had two, or three, or four
operations. In a community like ours here in Delaware, where
pediatric patients transition to adult services and adult
cardiologist sometime around their 20's, it's really important for
the entire cardiology community to be aware of what has happened in
terms of the successful staged treatment of children with
hypoplastic left heart syndrome and that is brought out very nicely
by the three authors who look at various accomplishments and
different techniques for managing these staged repairs. It is very
amazing to someone who has been observing this field for sometime
as I have, that many of these children are in fact surviving into
young adulthood and will require comprehensive cardiovascular
treatment, not just by neonatal specialist but by specialist in
adult congenital heart disease.
Carolyn:
Exactly, which is why such a timely state of the art articles both
of them for this issue. There is another state of the art article
that you were handling, Tim, "The Surgical Management of Infective
Endocarditis Complicated by Embolic Stroke", now that's an
important topic.
Timothy:
Absolutely, as we know up to a half or more of patients with
infective endocarditis primarily on their left sided heart valves
will have cerebral embolic problems and it has really been a
dilemma for many of us in terms of optimal timing for the cardiac
surgery with respect to the existence of cerebral injury from the
embolism, from hemorrhage that may occur, from hemorrhage that may
be exacerbated by placing the patient on the heart-lung machine,
etc, and this paper really takes an extremely comprehensive,
careful and judicious look at all of the evidence that has emerged
and it has been a confusing field of evidence as to how to best
optimally manage these patients with cerebral involvement from
infective endocarditis.
I think this paper is going to have a big impact. It appears that
there are a couple of messages that I took away from this paper.
Number one, we really need to use the full panoply of diagnostic
opportunities or diagnostic test for characterizing the nature and
the extent of the cerebral involvement in these patients and then
perhaps even more important, we need to convene what the authors
called the infective endocarditis team and that has to include not
just the surgeon, the cardiologist and the infectious disease
specialist but also the neurologist, the neuro-interventional
specialist, the neurosurgeon and so on because all of these
specialist need to contribute to the assessment and choosing the
optimal timing for these patients.
That is the central message of the paper. The authors also suggest
that we may be getting to the point where we need to update and
make sure that the guidelines that we're using are in fact current.
Current in the sense that the experience now with advance imaging
and with more aggressive management of the neurological or cerebral
issues really need to be factored into how best to handle these
patients, but I think this paper is going to have a big impact,
it's very well written and very thorough.
Carolyn:
I agree. In fact all the content we just discussed is just so rich.
Congratulations on such a beautiful issue. Marc, do you have any
last highlights you'd like our audience to hear about?
Marc:
I'd like to also mention two other original research papers that
will be featured in the surgery themed issue. One, in keeping with
the congenital theme that we had talked about is about the modified
[Straun's 00:19:08] procedure for palliation of severe Ebstein's
anomaly and this is a series actually from Professor [Straun
00:19:16] himself mostly originating from Children's Hospital Los
Angeles and essentially, the series here is that of 27 patients
about equal in gender distribution who were operated at seven days
of life, between 1989 and 2015.
It's very interesting that patients did well, the survival at ten
years is 76% and most of them have undergone successful Fontan
completion. I think this is a very important paper not only because
it is an extremely vexing and difficult problem to deal with
Esbtein's anomaly but it comes from the innovator of the operation
himself with his team and it provides much needed data regarding
the long term outcomes of these children with this very difficult
solution. I think this will be of great interest and also as we
commented before veering into the world of adult cardiology as
well, because fortunately most of these patients survive into
adulthood.
The other paper I wanted to touch upon which is also an original
research paper that will be in this themed issue, is a paper from
the CTSN Group looking at the impact of left ventricular to mitral
valve are being mismatched on recurrent ischemic MR after ring
annuloplasty and this paper used the free innovative and
interesting methods. As some of you may know, there were two large
files recently that were conducted by the CTSN looking at either
moderate MR at the time of coronary artery bypass grafting or at
severe ischemic mitral regurgitation. The randomizations were
different when the moderate MR was CABG lone versus CABG post
mitral valve repair and the severe MR was mitral valve repair
versus mitral valve replacement.
These studies have led to interesting conclusions that several will
know about but what's been interesting in the current study is that
they have gathered all patients who underwent mitral valve repair
from both studies, original randomized trials and they ended up
with about 214 patients who underwent mitral valve repair. The
others had moderate or severe MR and basically the point of this
study is to look at predictors of failure of mitral valve repair
and this is an extremely relevant problem, not only for the cardiac
surgical community I would venture, but also for heart failure
community and for JV General cardiology community. What the others
found is that the most important predictor of recurrent mitral
regurgitation after mitral valve repair was something called the
left ventricular and systolic diameter to ring size ratio and they
provide an algorithm which will have to be tested clinically with
regards to whether it is applicable and indeed changes outcome, but
this is a very important discovery in the field of ischemic MR and
enabling us to hopefully better understand and improve outcomes for
patients with this very difficult problem.
Carolyn:
I agree. Thank you so much, Marc and Tim for this most insightful
discussion. Thank you very much and to the listeners out there,
don't forget you've been listening to Circulation on the Run. Join
us next next week for more highlights and features.