Circulation January 12, 2021 Issue

This week's episode features authors David Kasss and Kavita
Sharma as they join Greg to discuss their article "Myocardial
Gene Expression Signatures in Human Heart Failure with Preserved
Ejection Fraction."


TRANSCRIPT BELOW:


Dr. Carolyn Lam:


Welcome to Circulation on the Run. Your weekly podcast, summary,
and backstage pass to the journal and its editors. We're your
co-hosts, I'm Dr. Carolyn Lam, associate editor from the National
Heart Center and Duke National University of Singapore.


Dr. Greg Hundley:


And I'm Dr. Greg Hundley, director of the Pauley Heart Center at
VCU Health in Richmond, Virginia.


Dr. Carolyn Lam:


I am so excited about today's feature paper. It talks about my
favorite topic, heart failure with preserved ejection fraction,
or HFpEF, this time giving us really novel myocardial gene
expression signatures in human HFpEF. Can't wait to go to that,
but I also can't wait to share about some of the really cool
papers in today's issue.


Dr. Carolyn Lam:


Now, we know that mitral valve-in-valve and valve-in-ring are
alternatives to surgical reoperation in patients with recurrent
mitral valve failure after a previous surgical valve repair or
replacement. But, what are the outcomes after transcatheter
mitral valve-in-valve or valve-in-ring procedures? And what is
the clinical significance of post-procedure residual mitral
stenosis or regurgitation? Well, we're going to find out in
today's paper. Dr. Dvir from Hebrew University in Israel and
authors examine the midterm outcomes in the Valve-in-Valve
International Data registry, which is a multicenter collaboration
and rolling cases performed between March, 2006 and 2020, in 90
centers worldwide.


Dr. Greg Hundley:


Wow, Carolyn. So what did they find?


Dr. Carolyn Lam:


Well, a total of 1079 patients were included with a median
follow-up of 492 days. 4-year Kaplan-Meier survival rate was
62.5% in the valve-in-valve, versus 49.5% in valve-in-ring
procedures. Significant residual mitral stenosis occurred in 8.2%
of the valve-in-valve, and 12% of the valve-in-ring patients.
Significant residual mitral regurgitation was more common in
valve-in-ring patients. The correlates for residue mitral
stenosis were smaller true internal diameter, younger age, and
larger body mass index. The only correlate for residual mitral
regurgitation was a valve-in-ring procedure. Significant residual
mitral stenosis and residual mitral regurgitation were both
independently associated with repeat mitral valve replacement.


Dr. Carolyn Lam:


So, significant residual mitral stenosis and/or mitral
regurgitation were not infrequent after mitral valve-in-valve and
valve-in-ring procedures, and we're both associated a need for
repeat valve replacement, so strategies to improve
post-procedural hemodynamics in mitral valve-in-valve and
valve-in-ring should certainly be further explored.


Dr. Greg Hundley:


Very nice, Carolyn. Well, my first paper, it really involves
results from the American Heart Association COVID-19
Cardiovascular Disease registry, and it comes from our own
associate editor, Dr. Justin Grodin from UT Southwestern Medical
Center. So Carolyn, obesity may contribute to adverse outcomes in
coronavirus disease, or COVID-19. However, studies of large,
broadly-generalizable patient populations are still lacking in
the effect of body mass index, or BMI, on COVID-19 outcomes,
particularly in younger, adults remains uncertain.


Dr. Carolyn Lam:


Yeah. It is an important question. And so, what did they find?


Dr. Greg Hundley:


Well, Carolyn, obese patients are more likely to be hospitalized
with COVID-19, and are at higher risk of in-hospital death or
mechanical ventilation, in particular, if they're young. So
individuals less than age 50 years. Obese patients are also at
higher risk for venous thromboembolism and dialysis. These
observations support clear public health messaging and rigorous
adherence to COVID-19 prevention strategies in all obese
individuals, regardless of age.


Dr. Carolyn Lam:


Wow. An important public health message. Well, my next paper is a
basic science one from doctors, Rayner and Karunakaran from
University of Ottawa Heart Institute in Canada. For the first
time, they investigated the role of RIP kinase 1, a coordinator
of NF-kappa B inflammation and cell death, in atherosclerosis.


Dr. Carolyn Lam:


They found that RIP kinase 1 expression was highly expressed in
early atherosclerotic lesions in humans and mice. In vitro, both
basal and TNF alpha stimulated NF-kappa B activity, and resultant
inflammatory gene expression was reduced in macrophages and
endothelial cells when RIP kinase 1 was silenced. In vivo
therapeutic administration of RIP kinase 1 antisense
oligonucleotide markedly reduced atherosclerotic lesion size and
macrophage content.


Dr. Carolyn Lam:


Together, these findings suggest that RIP kinase 1 drives
inflammation in early atherosclerosis, and targeting RIP kinase 1
therefore provides a novel preventive strategy to treat
atherosclerosis.


Dr. Greg Hundley:


Very nice, Carolyn. Well, my next paper comes from Dr. Kristin
Stanford from The Ohio State University. So, Carolyn, brown
adipose tissue is an important tissue for thermogenesis, making
it a potential target to decrease the risk of obesity, type 2
diabetes, and cardiovascular disease, and recent studies have
also identified brown adipose tissue as an endocrine organ.


Dr. Greg Hundley:


While brown adipose tissue has been implicated to be protective
in cardiovascular disease to this point, there are no studies
that identify a direct role for brown adipose tissue to mediate
cardiac function. This study was performed to address this issue.


Dr. Carolyn Lam:


So what did they find?


Dr. Greg Hundley:


Okay, Carolyn. The authors found that transplantation of brown
adipose tissue improves cardiac function via the release of the
lipokine 12,13di-HOME. Sustained overexpression of 12,13di-HOME
using tissue nanotransfection negated the delirious effects of a
high-fat diet on cardiac function and remodeling, and acute
injection of 12,13di-HOME increased cardiac hemodynamics via
direct effects on the cardiomyocyte. Furthermore, incubation of
cardiomyocytes with 12,13di-HOME increase mitochondrial
respiration. So, Carolyn, these results identify an endocrine
effect of brown fat to enhance cardiac function.


Dr. Carolyn Lam:


So interesting. Well, there are other very interesting types of
papers in today's issue. There's an exchange of letters between
Drs. Gui and Nahrendorf regarding the article Bone Marrow
Endothelial Cells Regulate Myelopoiesis in Diabetes.


Dr. Carolyn Lam:


In cardiology news, Tracy Hampton highlights articles from Nature
Biomedical Engineering on AI-based eye movements for
cardiovascular risk prediction, from Science on the metabolic
profiling of the failing and non-failing heart, and from Science
Translational Medicine on the heart healing effects of
extracellular vesicles.


Dr. Carolyn Lam:


There's an On My Mind paper by Dr. Pelliccia on gaps in evidence
for risk stratification for sudden cardiac death in hypertrophic
cardiomyopathy, as well as a Research Letter by Dr. Brown on the
association of inducible myocardial ischemia with long-term
mortality and benefit from coronary artery bypass graft surgery
in ischemic cardiomyopathy, which is a 10-year follow-up of the
STICH trial.


Dr. Greg Hundley:


Nice, Carolyn. Well, my articles: Professor Himbert has an
In-Depth article on the current indications for transcatheter
mitral valve replacement using transcatheter aortic valves,
valve-in-valve, valve-in-ring, and valve in mitral annulus
calcification. There's a Research Letter from Dr. Martin (Than)
regarding the single troponin rule-out of myocardial infarction.
And finally, Professor Isser has an ECG challenge involving chest
pain with ST-segment elevation in a young woman with a broken
heart.


Dr. Greg Hundley:


Well, now how about we proceed to that feature discussion?


Dr. Carolyn Lam:


Yay. Let's go, Greg.


Dr. Greg Hundley:


Well, listeners, we want to bring you to our feature discussion
today, and we have with us Dr. David Kass and Dr. Kavita Sharma
both from Johns Hopkins University in Baltimore, Maryland. David,
could you tell us a little bit about the background related to
this study and what hypothesis did you want to test?


Dr. David Kass:


Sure, Greg. My pleasure to be here. We have long had an interest
in the syndrome we know as heart failure with preserved ejection
fraction, going back, really, decades, and the difficulty in
assessing what's really wrong with the heart in this syndrome has
been that we get so little information from the tissue itself,
that most of the studies that have been done have been done at
the macro level and physiology level and epidemiology level.


Dr. David Kass:


But at Johns Hopkins, Kavita Sharma, who now heads up our heart
failure transplant group, had established a clinic, a HFpEF
clinic, one of the very few in the United States, and the
availability of both the patients through the clinic, and then as
part of this, right heart catheterizations associated with
endomyocardial biopsies being obtained, was really a very
extraordinary opportunity to examine tissue at a molecular level,
essentially for the first time. There's been no other data set
quite like this one.


Dr. David Kass:


So, we had already established both a patient population, very,
very well-phenotyped, very much symptomatic, and we had a tissue
bank. And as part of a consortium, a network consortium grant
that was sponsored by the American Heart Association, called the
Go Red for Women Network, we had a project that basically was
focused on trying to better understand HFpEF.


Dr. David Kass:


The impetus was really, no one knew anything about what's going
on in the heart at the molecular level. Really. There had not
been transcriptomic analysis ever done before, and there were
plenty of questions that we thought this might be able to answer.
Among them, how really different are these hearts from patients
who have, what we'll call, garden-variety heart failure, heart
failure with a low ejection fraction? That's seemingly not so
controversial now, but actually there's still controversy as to
exactly what's wrong with these hearts, and so we thought we
would be able to tease that out.


Dr. David Kass:


Then it's also been, I think, widely discussed that this is a
very heterogeneous disease or syndrome, really, that has a lot of
different factors, comorbidities, that are associated with it. So
question two was really, how cohesive is the molecular signature
that you might see in the myocardium? Is it going to be
hopelessly heterogeneous as well, in which case, what does that
say about our possibility to develop drug therapies when the
underlying biology may be very, very heterogeneous? And if not so
heterogeneous, question followup would be, what signatures might
be there in subgroups that we could identify, and with subgroup
analysis then, help us target in a more personal medicine
fashion, ultimately, a therapeutic for the syndrome?


Dr. Greg Hundley:


Very nice. So, David, how did you assemble a study population,
and what was your study design?


Dr. David Kass:


In this sense, this was very much an ongoing effort by Dr. Sharma
and what was the HFpEF clinic team. Back, probably about 4 years
ago, maybe even more, she had started to become interested in
this and had amassed a clinic population while she was a
resident, and then as a senior resident became more and more
interested in this and this became her fellowship project when
she was a cardiology fellow at Hopkins.


Dr. David Kass:


And by the time I became more involved with this, basically she
had it in operation with study nurses and seeing patients. It was
very clinically-oriented. There was some sort of more, I would
say, population-level data being collected and studies being
done, but nothing like quite what we did here. But that was
there.


Dr. David Kass:


So, in terms of a study design, this was almost more a biobank.
At this point, there was a cadre of patients she had been
following. She had been following this group for some time.
Basically, in a freezer we had endomyocardial biopsies under an
IRB-approved protocol that had been obtained, and in part we were
sort of waiting to get enough tissue together so we had a large
enough data population and enough sample, and then really
thinking through what might we be able to look at in these
pieces, knowing full well that very little had been done. So
almost anything we came up with, and we've been doing quite a few
other things now as well, was going to be new, so I suppose the
simplest study design of all.


Dr. Greg Hundley:


So, what did you find?


Dr. David Kass:


Well, going through those initial questions. Question number one,
is there a unique molecular signature? We're looking at using
what's called RNA-Seq, which is the newest generation of RNA gene
expression analysis, in these myocardial biopsies. The answer
was, yes, actually. There was a very unique signature. And this
was all done using what we call agnostic bioinformatics
approaches, where you just give the data, you give all the genes
that are different between HFpEF and a control group, we had a
control group, donor hearts. You look at basically the HFrEF
group, the people with low ejection fraction, versus control.
What are those differentially expressed genes? And of course you
have your control.


Dr. David Kass:


So there are three groups and you get a series of little dots in
what's called principal component analysis, and it was very
clear, right from the beginning, that these groups separated, and
this was just purely a statistical approach to say, are they
different?


Dr. David Kass:


And then we asked further, are they still different even if we
adjust for what are the common comorbidities and the things that
differentiated, often, HFpEF from other forms of heart failure,
specifically age, sex, having a large body mass index, having
diabetes, these were all things that were more prevalent and more
severe in the HFpEF group. So we adjusted for these things,
again, sort of statistically, and redid this, and it's still
absolutely separated. So question one, are they different at the
transcript level? Yep. They're different.


Dr. David Kass:


And then, question two is basically, despite the heterogeneity,
if you start digging into the genes, what kinds of genes are
being differentially regulated? Is there a signature that becomes
cohesive and consistent among the patients within the HFpEF
group? The answer to that was, yes. And this too was very
interesting because we also did an adjustment for the
comorbidities, and what we found were the genes that were
upregulated in HFpEF, that actually turned out mostly to be
down-regulated in the other form of heart failure. Genes
specifically associated with the manufacturing of ATP by
mitochondria, the ATP synthase genes, those genes were
significantly upregulated in HFpEF, but once you adjusted for
body mass index, a lot of those pathways disappeared. So, the
class of genes that were up regulated was in fact related to
comorbidities.


Dr. David Kass:


Then we did the opposite. We looked at those genes that are
down-regulated, and found that a large group of genes that were
quite different, that are not on the tip of most people's tongues
for what goes on in heart failure, mostly associated with protein
processing, trafficking, autophagy, the process of protein
recycling, endoplasmic reticular stress, which was something that
the journal senior editor, Joe Hill, had talked about and
published about earlier in the year in a mouse paper where he
first came up with this idea that ER stress might be important.
Well, looks like it's important in these humans. So, we found
some unique signatures.


Dr. David Kass:


And then the last thing I suggested we would look at is whether
we could get subsets from the molecular signatures, and the
answer to that was, yes. Here we kind of threw the genes at a
program and said, "You come up with clusters, purely based on the
genes." That's it. No clinical information whatsoever. What it
came out with were three groups, and very interestingly, there
was a mortality difference between these groups just based on
their transcript. One of the groups looked at pretty close, or
closer, to HFpEF to reduced EF heart failure, and indeed, the
genes that it came up with were typical of hypertrophy and
remodeling and matrix remodeling, and that was the one with a
group with the highest mortality. And then there was sort of a
very different group with small hearts, relatively low levels of
natriuretic peptide, an inflammatory pathway signature. Not the
kind of thing we're to looking at and say, "Oh yeah, this is
obviously heart failure," and yet they were equally symptomatic,
tended to be a few more on the female side than male side.


Dr. David Kass:


So, I think, in the end, that study was very successful for all
the things we were trying to do, really. That it's distinctive,
that there are subgroups that we can identify at the
transcriptome level, despite the heterogeneity, and we've got a
list of genes now, pathways, really, that look to to be uniquely
relevant.


Dr. Greg Hundley:


Very nice summary. Well, let's turn to your colleague, Dr. Kavita
Sharma, who is also with us today and helped assemble this
wonderful cohort. Kavita, how would you put these findings in the
context with some of the other literature that's been published
in heart failure preserved ejection fraction?


Dr. Kavita Sharma:


Hi, good morning. Thanks for the opportunity. That's a great
question. The idea of trying to phenotype HFpEF has really been
around, for now, a couple years, and that's driven by the fact
that we have no therapeutic agents to date that have really
affected outcomes in this population, in spite of the fact that
half of all heart failure is classified as HFpEF and we have many
therapies for HFrEF, or low ejection fraction patients.


Dr. Kavita Sharma:


And the thought is that, perhaps, it's a heterogeneous population
and we're lumping to many different types of patients together.
And so there have been a number of efforts to date to try to
phenotype this population, but most of these have been centered
around clinical comorbidities, and distinct groups have been
identified, but without a clear sense of what is driving
mechanistic differences between the groups, and then how to take
it to the next step to target therapeutic agents to specific
populations within HFpEF.


Dr. Kavita Sharma:


I think this is a big step closer to trying to really understand
how we can target therapies. So, we've seen efforts at
phenotyping and there are some overlap between the three groups
that we identified from our RNA sequencing work, but this is now
giving us a clue as to how to target mechanisms of disease.


Dr. Greg Hundley:


Very nice. Well, Kavita what do you see is the next study to
perform, really, in this space, to follow your work?


Dr. Kavita Sharma:


Our goal is to really perform a comprehensive, as we call it,
omics approach to phenotyping and HFpEF. We are actively looking
at metabolomics, both from the blood and the tissue in
collaboration with investigators at U Penn, we hope to also look
at proteomics, and eventually single cell sequencing, as well as
really trying to understand some of the actual myocyte-level
contractility issues. And this is work that actually has just
come out as well from our group, looking at sarcomere function in
HFpEF from the right ventricle. Our hope is that each of these
areas is going to further our understanding of myocardial
deficits, so to speak, and areas that we could target for
therapies.


Dr. Greg Hundley:


Very nice. David, do you have anything to add to that?


Dr. David Kass:


No. I think Kavita said it very, very well, and clearly the goal
is to ultimately develop a more mechanistically-driven,
personalized approach to the subsets of HFpEF so that hopefully
we get a therapy that actually is going to work. These are not
tiny subsets of this group. Remember this is half of all heart
failure and that's a big number, and even a subgroup that might
represent one-quarter of half of all heart failure is still a big
number, and so none of this is ever going to be like an orphan
disease suddenly where we're dealing with a very small group of
people.


Dr. David Kass:


But even if it was, it would still be a major step forward, but
it's not going to be that. I think what you're going to hopefully
come up with, with a signature that can be targeted and with the
therapy that's effective on the basis of that, is going to, I
think, help a large population.


Dr. Greg Hundley:


Well, listeners, we want to thank Dr. David Kass and Dr. Kavita
Sharma, both from Johns Hopkins University in Baltimore, Maryland
for bringing us this new information related to RNA sequencing to
really help better phenotype patients with heart failure and
preserved ejection fraction, so that in the future, we may have
therapies that can help this patient population.


Dr. Greg Hundley:


This program is copyright of the American Heart Association,
2021.