Circulation October 31, 2017

Dr. Carolyn
Lam:              
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.


                                               
This week's journal is really special. It is the 2017
cardiovascular surgery-themed issue of "Circulation." To
summarize this issue, I am so privileged to have the editors, Dr.
Marc Ruel from University of Ottawa Heart Institute, as well as
Dr. Timothy Gardner from Christiana Care Health System. Welcome
gentleman.


Dr. Timothy Gardner:     Hello.


Dr. Marc
Ruel:                  
Hi, Carolyn. Glad to be here.


Dr. Carolyn
Lam:              
Thank you for another beautiful themed issue, Marc. I see that
there are four general themes within this theme, if I may. The
first of which are a collection of papers on coronary disease and
coronary surgery. Could you maybe start by giving us an overview
of that?


Dr. Marc
Ruel:                  
One of the main topics that have been looked at in the
surgical-themed issue this year is coronary surgery. We all know
well that 2016, 2017, the academic year was quite fertile in
providing new information around coronary surgery, especially
with the release of the ART trial had actually scientific
sessions of the American Heart Association the last November with
simultaneous publication.


                                               
Interestingly, the cardiovascular surgical-themed issue has
several coronary papers and one that deals with essentially with
graft failure, if you will. There's an in-depth review written by
Mario Gaudino, who is well known and does fantastic work at
Cornell, who essentially put a team together looking at several
aspects of coronary graft failure. I guess we can say that these
are looked in quite great depth, and they deal with several
aspects of what would lead to a coronary bypass graft to fail.


                                               
First and foremost, Mario and the team look at the blood
components. Then the artery and the native bed itself. Then they
focus a lot on the conduit, not only the nature of the conduit
being a venous versus arterial conduit, but also the way of
storing the conduit prior to performing the bypass. Also, the
technique that's used around the use of that conduit.


                                               
Finally, I'd say that the review culminates with the patient
bioreactor, for lack of a better term, aspect. Endothelial
dysfunction in the patient with diabetes, age, gender,
hypertension, dyslipidemia, etc., all these things that do act as
a significant substrate for the fate of the conduit vessel.


                                               
A very unique, I think, first-time, in-depth review that,
certainly, the "Circulation" editorial team and reviewers were
very excited about. I think this will be quite impactful and
provide very, very detailed information for future research and
future improvement and fate of the coronary graft conduits.


Dr. Carolyn
Lam:              
And, Dude, I agree. It's the new look at perhaps a classic, old,
central surgery, the cardiovascular surgery. Very nice, indeed.


Dr. Marc
Ruel:                  
Precisely, thank you. We also have a couple of important, seminal
original papers within the realm of coronary surgery. In fact,
these also deal, to some extent, with the fate of conduits and
certainly how they work in the patient population in long ago
bypass surgery.


                                               
One is a randomized control trial, a single center randomized
control trial that was performed in South Manchester. It's called
the VICO trial, a study comparing vein integrity and clinical
outcomes. Essentially, the study looked at open vein harvesting
versus two types of endoscopic vein harvesting for coronary
artery bypass grafting.


                                               
The study was performed at a single center in England with three
sound methods, having three groups of 100 patients who were
compared with regards to the vein harvest technique. The primary
outcome was with regards to actual vein integrity, looking at
muscular damage and endothelial function and integrity on
microscopy.


                                               
Surprisingly and actually quite reassuredly that there were very
few differences between endoscopic vein harvest and open vein
harvest. Certainly the investigators also looked, as one of their
secondary outcomes, at quality of life. It was quality of life
that was gained in patients who had endoscopic vein harvest
versus those who had open vein harvest.


                                               
Overall, there was no difference in major adverse cardiac events.
Therefore, showing at least in an internally valid fashion that
these investigators at their center could do endoscopic vein
harvesting as well as open vein harvesting.


Dr. Carolyn
Lam:              
I know that there are other original research papers, perhaps.
Would you like to highlight any of them?


Dr. Marc
Ruel:                  
Yes, for sure. Carolyn, there's also one more coronary surgery
paper, which I wanted to highlight and that is the paper
entitled, "Does Use of Bilateral Internal Mammary Artery Grafting
Reduce Long-Term Risk of Repeat Coronary Revascularization?"


                                               
This is a multi-center analysis with first author is Iribarne
from Northern New England. Essentially, seven medical centers got
together and took about 20 years of consecutive CABGs with a
total number of 50,000 operations, or just shy of 50,000
operations.


                                               
The median duration of follow-up was 13 years, and these patients
were well matched together using a propensity matching scheme. I
think this paper and this research is unique and of high impact.
Even though it does have shortcomings of not being a randomized
control trial, it is very welcome information, especially in
light of the recent ART trial, which, as you know, did not show
any difference at five years analysis between single and
bilateral internal thoracic artery use.


                                               
The particularity of the Iribarne paper is that it is a very
large data set up with close to 50,000 patients. It is
multi-centered, therefore, it is real life. It is a consecutive
series. The patients are extremely well matched, and it is
remarkable to hear that the patients, in fact, had no difference
in mortality until about five years after the operation.


                                               
As opposed to many previous series where single versus bilateral
internal mammary grafting shows a mortality difference very early
on, which always raises the suspicion of poor matching or
confounding by indication, if you will, this paper did not have
that.


                                               
Finally, the follow-up was quite long and at about six years,
there was really a mechanistic signal with regards to repeat
revascularization events, which seemed to match the difference in
late mortality. There was no difference in early and five-year
mortality, but afterwards as repeat revascularization events
started to occur more frequently in the single mammary group,
this was matched by a difference in mortality, as well.


                                               
I think a very useful, large, long follow-up
mechanistically-based information that I think adds very
significantly to the current information we have about bilateral
versus single mammary use.


Dr. Carolyn
Lam:              
Thank you, Marc. Two original papers, highlighted, dealing with
really very important modern controversies in this area. Open
vein versus endoscopic vein harvesting, single versus bilateral
mammary artery bypass. Excellent.


                                               
Let's move on now to the next sub-theme, if you will. And that is
the collection of papers on "Adult Congenital Heart Conditions,"
really, really an increasingly important and growing population
that we're seeing. Tim, would you like to summarize maybe some of
the highlights of the papers there?


Dr. Timothy Gardner:     The first paper, as
you point out, is focused on adult patients with repaired
tetralogy of Fallot. This series came from the UK and it examines
the course of almost 60 patients, at a mean age of 35 years
following a repair of tetralogy as infants or young children,
developed right heart failure and required pulmonary valve
replacement.


                                               
This is a common scenario that we're seeing, successfully
repaired children who appear to do well but as they get into
their late 20s and 30s, their pulmonary valve function, which is
often inadequate or not even present valve, require an
intervention.


                                               
The important learning here is that pulmonary valve replacement,
either surgically or by catheter technique, was shown to be
highly effective in salvaging right ventricular function. That is
based on imaging studies as well as hemodynamic studies of right
ventricular function. There was an almost, in this group of
patients, almost an immediate reverse remodeling of the right
ventricle after placement of the valve, that continued to improve
over time.


                                               
This was, I think, quite reassuring. There, historically, was a
bit of a reluctance to operate on these patients as their right
heart was failing, despite the fact that without some
intervention to take the volume load off of the RV, the patients
didn't do well. This is good news for an important group of
patients who we are all seeing, who oftentimes present to the
adult cardiologist because of this right ventricular failure
problem. A nice, reassuring study.


                                               
Actually, the other two congenital papers are, again, focused on
the infant. They both deal with the infant with hypoplastic left
heart syndrome or single ventricle pathology. The first paper
seems sort of specialized in terms of its focus, "The Optimal
Timing of Stage-2-Palliation for Hypoplastic Left Heart
Syndrome." This was a report from the NIH Pediatric Heart
Network. They had a single ventricle reconstruction trial.


                                               
This network is comprised of about 10 North American centers,
both in the U.S. and Canada and has provided excellent data about
the management of pediatric heart disease but, in particular, the
single ventricle trial has been excellent.


                                               
In this particular paper, they look at the optimal timing for
stage-2 repair. Just to remind ourselves, the first part of the
three-stage treatment for hypoplastic left heart syndrome is the
Norwood procedure, which has to be done shortly after birth, as
the patent ductus arteriosus closes and converts, essentially,
the single right ventricle into the systemic ventricle.


                                               
The stage-2 comes along, usually done with a Glenn-type of shunt,
increases pulmonary blood flow and stabilizes these infants until
they can reach the age for, and the heart function for definitive
repair. This has been a particularly difficult problem for the
congenital heart surgeons. What is the optimal timing?


                                               
This study, which involved over 400 patients, identified optimal
timing for the second stage between three and six months after
the Norwood. I think this was very reassuring, is reassuring or
supportive for the congenital heart community in terms of both
patients and also good evidence base that a delay of three to six
months does, in fact, produce the best transplant-free survival.


                                               
In fact, the other aspect of this observation was that infants
who developed the need for another second stage operation sooner
than that did not do well, and the reasons for the required
earlier surgery could be failure of the initial operation or
additional anatomic risk factors. But this, I think, was an
important, large series, multi-center study that will prove to be
very helpful in sorting out this complex timing of a three-stage
repair.


                                               
Just to comment, again, for readers who don't deal with infant
congenital heart treatments very often, there's been a remarkable
amount of success over the last two decades in salvaging and
saving these very difficult infants with the hypoplastic left
heart syndrome. In fact, an additional paper in this
surgery-themed issue, comes from the UK and is, in fact, a report
on the findings from the UK-wide audit of the treatment of
infants with hypoplastic left heart syndrome.


                                               
In fact, their findings, in this sort of real world, not in the
Pediatric Heart Network trial group, is very similar. They found
that infants who got to the second stage without additional
refinement of the initial Norwood procedure and were able to be
successfully treated with a Glenn shunt somewhere in the
four-to-six-month age range, did well. They actually made the
point that the anatomy was more of a determinant than anything
else.


                                               
I think that this particular review will reinforce what the
congenital heart surgeons have learned about optimal timing for
this three-stage treatment of what previously were
unreconstructable children.


Dr. Carolyn
Lam:              
Thank you so much, Tim. Isn't it wonderful the way papers come in
and they're actually complementary and consistent with one
another. We're just so lucky to be publishing all of these great,
high-quality, impactful papers in "Circulation."


                                               
Moving on, the next paper actually reminds us why this is a
cardiovascular surgery-themed issue and not just a cardiac
surgery-themed issue. Didn't we just say that earlier, Marc? This
one is on abdominal aortic aneurysm treatment. A population-based
landscape of this. Could you tell us a little bit more about that
one?


Dr. Marc
Ruel:                  
Absolutely. Carolyn, you're entirely right. We must remember that
"Circulation" is also about peripheral vascular disease, saying
this earlier, or cardiovascular surgery and anesthesia consult
also when it encompasses vascular surgery. Precisely to that
effect, one of the papers in our cardiovascular surgical-themed
issue is a landscape population based analysis from Finland that
looks at the incidence of abdominal aortic aneurysm between the
years of 2000 and 2014.


                                               
Finland has a population of about 5.5 million and remarkably has
a very circumscribed healthcare system. They do not have an
organized system of AAA care as some other countries have shown
to have and potentially benefit from, but rather they have a
treatment of this condition at several institutions, many of
which may not be high volume.


                                               
I think the paper is remarkable is that it is very well nested in
terms of a population. It provides a comprehensive landscape of
where this condition has evolved to over the last few years.
Obviously, we see in the results from the authors that the
mortality has decreased quite a bit, but also the incidence,
probably as a result of better control of risk factors. And also
the incidence of rupture outside the hospital.


                                               
One thing that came out of this paper, as well, is a potential
cohort of the benefits gained from developing an organized system
of AAA care, from the reason that the mortality of AAA rupture in
Finland was still quite high, despite this being a modern series.
In fact, when you include ruptures, before arrival to hospital
and at arrival to hospital, the overall mortality was almost 80%
for ruptured AAA.


                                               
Perhaps one message that comes out of this is that there may be a
benefit in having specialized centers dealing with these
conditions, especially as they are in the process of rupturing.
One last observation was, obviously, the increasingly prevailing
role of endoscopic vascular repair in the treatment of this
condition, which, in fact, has now surpassed open repair as the
dominant method of elective repair.


                                               
I think, overall, a very comprehensive, well-nested, country-wide
with good follow-up landscape of the AAA condition in a country
that has essentially a similar socioeconomic status to much of
the western world. Therefore, with external generalized ability
to some extent.


Dr. Carolyn
Lam:              
Exactly, and contemporary data. I really enjoyed that you paired
those with an excellent editorial, as well. Finally, before we
wrap this up, I have to ask Tim to comment on this next paper,
and it's on ventricular assist device malfunctions, I love the
title, "It's More Than Just The Pump." Of course, as a heart
failure physician, this one's very close to my heart. Forgive the
pun. But, Tim, could you tell us about that?


Dr. Timothy Gardner:     This paper comes
from the University of Pittsburgh and their artificial heart
program. Robert Kormos is the first author and he's been one of
the stalwart leaders in the use of LVADs and other pump devices.
He reports on their experience with over 200 both HeartMate and
HeartWare ventricular assist devices.


                                               
It was interesting when we reviewed this paper by the editors,
there was some thought that maybe this was a little too
engineering focused and so on, but I think the point of the paper
is that, as they say in the very first line in their report,
reports of LVAD malfunction had focused on pump thrombosis.


                                               
But they point out very appropriately that, in fact, controller
failure, battery failure, cable failure and other causes of
device failure, which can be critical and life threatening and so
on, are engineering issues. It reminds us that when we're
managing this difficult group of patients, and we're seeing many
more patients today with getting LVADs than 10 or 20 years ago,
we need to have the bioengineering abilities and resources
available.


                                               
Even the surgeon and the critical care physician who is dealing
with these patients either has to acquire this kind of knowledge
or capacity himself or herself, or needs to have a good
bioengineer nearby.


                                               
What's interesting, I think, that all of us define that these
mechanical failures were more common in this pretty big
experience than what we've more clinically worried about, which
was thrombosis of the pump.


Dr. Carolyn
Lam:              
Exactly. That's so wonderful. And you know it just leads me to
really thank you both, Marc and Tim, for this extraordinarily
excellent selection of original research, state-of-the-art and
perspective articles and editorials on congenital, coronary,
vascular and heart failure surgery. This really appeals not just
to the cardiovascular surgeons but really to the vast readership
of "Circulation."


                                               
Thank you for a wonderful themed issue and thank you for this
great podcast.


Dr. Timothy Gardner:     Well, thank you.


Dr. Marc
Ruel:                  
Thank you very much, Carolyn.


Dr. Carolyn
Lam:              
Listeners, don't forget to tune in again next week.