Circulation September 13, 2022 Issue

This week, please join authors Svati Shah and Senthil
Selvaraj as well as Guest Editor and Editorialist Manuel Mayr as
they discuss the article "Metabolomic Profiling of the Effects of
Dapagliflozin in Heart Failure With Reduced Ejection Fraction:
DEFINE-HF" and the editorial "SGLT2 Inhibitors in Heart Failure:
Targeted Metabolomics and Energetic Metabolism."


Dr. Carolyn Lam:


Welcome to Circulation On 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, Associate Editor, Director of the
Pauley Heart Center at VCU Health Richmond, Virginia.


Dr. Carolyn Lam:


In today's feature paper, we will be talking about the
metabolomic profiling of the effects of dapagliflozin in heart
failure, and this is from the DEFINE-HF trial. It's just such a
cool paper with a lot of insights you have to hear from the
authors. But, before we get there, let's talk about some of the
other papers in today's issue. Shall we, Greg?


Dr. Greg Hundley:


You bet, Carolyn. Well, how about if I go first?


Dr. Carolyn Lam:


Please.


Dr. Greg Hundley:


Thank you, Carolyn. My first paper comes to us from Professor
Paulus Kirchhof from the Universitäres Herzzentrum in Hamburg.
Carolyn, in the randomized EAST-AFNET 4 study, so the early
treatment of atrial fibrillation for stroke prevention, these
trial investigators demonstrated that systematic initiation of
early rhythm control reduced adverse cardiovascular outcomes in
patients with recently diagnosed atrial fibrillation and stroke
risk factors. However, the effectiveness and safety of early
rhythm control in patients with multiple cardiovascular
comorbidities is not known. Carolyn, in this study, it was a
prespecified sub-analysis of the EAST-AFNET 4 trial and it
compared the effectiveness and safety of early rhythm control
with usual care stratified into patients with high CHA2DS2-VASc
scores of greater than or equal to 4.


Dr. Carolyn Lam:


Nice. Okay. Important question, what did they find?


Dr. Greg Hundley:


Right, Carolyn. Quite a bit of data in this study, so let's walk
through it carefully. First, in regards to the study population,
the EAST-AFNET 4 randomized 1093 patients with CHA2DS2-VASc
scores of greater than or equal to 4, these were predominantly
women, 61% female, and then also 1,696 patients with CHA2DS2-VASc
of less than four, and these were predominantly men, so only 37%
women.


Now let's get to the date. Early rhythm control reduced the
composite primary efficacy outcome of cardiovascular death,
stroke, or hospitalization for worsening heart failure or for
acute coronary syndrome in patients with high CHA2DS2-VASc scores
of greater than 4, but not in patients with CHA2DS2-VASc scores
of less than 4. Second, now Carolyn, the primary safety outcome,
so death, stroke, or serious adverse events of rhythm control
therapy, was not different between study groups in patients with
high CHA2DS2-VASc scores of greater than 4, but occurred more
often in patients with low CHA2DS2-VASc scores randomized to
early rhythm control. Now Carolyn, life threatening events or
death were not different between the groups. When female sex was
ignored for the creation of high and lower groups, the
interaction P was not significant for the primary efficacy
outcome, but remained significant for the primary safety outcome.


Dr. Carolyn Lam:


Oh, you are right. A lot of interesting data here. What's a take
home message?


Dr. Greg Hundley:


Right, Carolyn. So the take home message is the following.
Patients with recently diagnosed atrial fibrillation and multiple
cardiovascular comorbidities should be considered to have
priority access to early rhythm control to reduce cardiovascular
outcomes, and a specific trial of early rhythm control in these
patients is really needed as a next step.


Dr. Carolyn Lam:


Oh, thank you, Greg. The next paper focuses on arrhythmogenic
right ventricular cardiomyopathy, which we know is characterized
by a high propensity to life threatening arrhythmias and
progressive loss of heart muscle. More than 40% of reported
genetic variants linked to arrhythmogenic right ventricular
cardiomyopathy, or ARVC, reside in a gene called plakophilin-2,
or PKP2. In today's paper, Dr. Delmar and Lundby from NYU
Grossman School of Medicine and University of Copenhagen,
respectively, and their colleagues, described a comprehensive
characterization of the ARVC molecular landscape using a
multidisciplinary approach including human samples from ARVC
patients with PKP2 mutations and left ventricular ejection
fraction above 45%, as well as PKP2-deficient murine and human
induced pluripotent stem cell-derived cardiomyocytes. They
studied all of these with comprehensive proteomics and functional
analysis.


Dr. Greg Hundley:


Wow, Carolyn, another great study in circulation combining both
preclinical murine models as well as data from human subjects.
So, what did they find?


Dr. Carolyn Lam:


Precisely, Greg. Here's what they found. Loss of nuclear envelope
integrity and subsequent DNA damage is a key substrate in the
molecular pathology of AR VC. The authors further showed
transcriptional down regulation of proteins of the electron
transcript chain as an early event in the molecular
pathophysiology of the disease prior to an ejection fraction
falling below 45%. This associates with increased oxidant
production, with the clinical message being, therefore, that the
authors propose therapies that limit oxidant formation may be a
possible intervention to restrict DNA damage in ARVC.


Dr. Greg Hundley:


Very nice, Carolyn. Okay, our next paper comes from Dr. Donald
Lloyd-Jones from Northwestern University, the Feinberg School of
Medicine. Carolyn, you can tell the change in inflection of my
voice because it's time for another Carolyn's quiz. Carolyn,
open-ended question. Can you remind us of life's essential eight?


Dr. Carolyn Lam:


Oh boy, Greg. It's like asking me to name the dwarfs. I know I'm
going to forget one, but here you go. Diet, exercise,
cholesterol, weight, smoking, sugar must be there, diabetes,
blood pressure. You see, I got seven. What's the eighth?


Dr. Greg Hundley:


Yeah. Remember seven dwarfs, Sleepy.


Dr. Carolyn Lam:


Sleep.


Dr. Greg Hundley:


Very good. Great job, Carolyn.


Dr. Carolyn Lam:


Thank you.


Dr. Greg Hundley:


Recently, the American Heart Association recently published an
updated algorithm for quantifying cardiovascular health, the
Life's Essential 8 score. In this study, the investigative team
quantified US levels of cardiovascular health using the new
score. They included non-pregnant, non-institutionalized
individuals aged 2 through 79 years who were free of
cardiovascular disease from the National Health and Nutrition
Examination Surveys that were conducted between 2013 and 2018.


Now, for all participants, they calculated the overall
cardiovascular health score, and it ranged from 0, which is
really low, to 100, which is the highest, as well as the score
for each component. And Carolyn, yes, you are very close.
Remember the eight? Diet, physical activity, nicotine exposure,
sleep duration, body mass index, blood lipids, blood glucose, and
blood pressure, and they used published American Heart
Association definitions of these. The cardiovascular health
scores were assessed across strata of age, sex, race, ethnicity,
family income, and depression.


Dr. Carolyn Lam:


Okay, Greg. What did they find?


Dr. Greg Hundley:


Right, Carolyn. There were 23,400 plus participants, representing
201,728,000 adults and 74 million children. The overall mean
cardiovascular health score was 64.7 among adults using all eight
metrics, and it was 65.5 for the three metrics available of diet,
physical activity, and BMI among the children and adolescents
that were aged 2 through 19 years.


Now, for the adults there were significant differences in mean
cardiovascular health scores by sex, age, and racial ethnic
group. Mean scores were lowest for diet, physical activity, and
the BMI metrics. There were large differences in mean scores
across demographic groups for diet, nicotine exposure, blood
glucose, and blood pressure. In children, diet scores were low,
40.6, and were progressively lower in higher age groups. Large
differences were also noted in mean physical activity and BMI by
sociodemographic group.


Carolyn, this study basically identifies wide ranges of scores
across multiple domains of the essential eight, and thus, this
new Life's Essential 8 score helps identify large group and
individual differences in cardiovascular health. Additionally,
overall, cardiovascular health in the US population remains well
below optimal levels, and there are both broad and targeted
opportunities to monitor, preserve, and improve cardiovascular
health across the life course in both individuals, as well as the
population at large.


Dr. Carolyn Lam:


Wow. Thanks, Greg. Truly really interesting. Everyone's going to
have to pick up that paper and all the other papers in this
issue, because there's also an In Depth paper by Dr. Whelton on
“Harmonization of the ACC/AHA and ESC/ESH Blood Pressure
Hypertension Guidelines, Comparisons, Reflections, and
Recommendations. There's a Research Letter by Dr. Munshi on the
accurate classification of cardiomyopathy etiology by chromatin
accessibility.


Dr. Greg Hundley:


Carolyn, I have got to report an exchange of letters from
Professor Sun and Weng regarding the article, “Legumain Is an
Endogenous Modulator of Integrin αvβ3 Triggering Vascular
Degeneration, Dissection, and Rupture.” And then Carolyn, lastly,
there's a Perspective piece from Professor Vidal-Petiot entitled,
“Thresholds for Hypertension Definition, Treatment Initiation,
and Treatment Targets: Recent Guidelines at a Glance.” Well,
Carolyn, how about we get on to that feature discussion?


Dr. Carolyn Lam:


Yes, let's go Greg.


Wow, we have a star stud cast for today's feature discussion, and
on a star studied topic, if I may. It's on the SGLT2 inhibitors,
this time in the DEFINE-HF study and really going into the
mechanism of action of SGLT2 inhibitors. Now, that's one question
I personally get all the time. How do these things work? Today's
paper brings us one step closer, for sure, in the understanding.
I'm so grateful to have the first author, Dr. Senthil Selvaraj
from University of Pennsylvania, as well as the corresponding
author of the paper, Dr. Svati Shah, associate editor, as well as
the corresponding author from Duke Molecular Physiology
Institute. We also have Dr. Manuel Mayr who was both the guest
editor and editorialist for this paper, and Dr. Mayr is from
Kings College London, British Heart Foundation Center. Welcome,
everyone. Senthil, get us started here. The DEFINE-HF study, just
a quick summary, what that was about and then what you did, what
you found.


Dr. Senthil Selvaraj:


Absolutely. Good morning, everyone, or maybe good evening for
your time, Carolyn, but we were very excited about this study and
the ability to do targeted metabolomic profiling in DEFINE. This
audience is well familiar with the fact that SGLT2 inhibitors are
foundational therapy in heart failure reduced ejection fraction,
and the interesting thing is, despite a lot of literature, we
still don't know why. Whether it relates to change in
inflammation or endothelial function, but given the mechanism of
action, metabolism is sort of at its core. So in this study we
sought to identify metabolic pathways that were associated with
dapagliflozin treatment using this targeted metabolomics platform
in which we assayed 63 metabolites, acylcarnitine, which are
markers of fatty acid oxidation, several amino acids, and
ketone-related metabolites.


To do this, we studied 234 participants from DEFINE, which is a
12-week placebo-controlled trial of dapagliflozin in this
population, and we perform principal components analysis for
dimensionality reduction techniques. In this study, briefly we
found that, first, our principal components analysis yielded 13
different factors that accounted for the substantial proportion
in the variation of the data, and that two in particular,
ketone-related metabolites and short acylcarnitines in factor 6,
as well as medium-chain acylcarnitines in factor 7 were
differentially associated with dapagliflozin treatment.
Specifically, there were increases in several ketone-related
metabolites and short acylcarnitines, as well as several
medium-chain acylcarnitines, really speaking to, potentially,
changes in fatty acid as well as ketone biology with
dapagliflozin treatment.


The second aim of our study was to look at changes in metabolites
and changes in endpoint studying DEFINE, which included NT-proBNP
as well as KCCQ scores. We found that dicarboxylate long-chain
acylcarnitines and aromatic amino acids really related to
worsening heart failure endpoints there. So, a lot to impact, a
lot that we found, and appreciative about the opportunity.


Dr. Carolyn Lam:


Oh, wow. Thank you so much for that amazing summary. Svati, I've
heard you speak so many times on metabolomics on our calls, but
this is really so important. First, I think the question is,
congratulations for thinking ahead of time to collect the samples
and to do all of this. Congratulations on that. Could I ask if
you went in with any specific hypothesis or were you surprised by
these findings, Svati?


Dr. Svati Shah:


Yeah, Carolyn, thank you so much. It was such a pleasure to work
with Senthil on this and I really want to highlight what an
incredible early career investigator he is. He's really going to
set the metabolism world on fire. I also wanted to say thank you
to the PI of the clinical trial, the parent clinical trial
DEFINE-HF Mikhail Kosiborod, who did the really hard work of
collecting the samples along with the clinical trial itself.


To me, what's really cool is to be able to take a clinical trial
like this with really important clinical outcomes well
adjudicated and to be able to dig into the mechanism at a
metabolic level of what might be going on with SGLT2 inhibitors.
Going into this, Carolyn, we suspected that ketone-related
biology was at play. There have been studies in other
populations, non-HFrEF populations, that have shown that SGLT2
inhibitors have what appears to be beneficial impacts on ketone
biology and induced ketosis. So, going into this, we suspected
that this ketone pathway was going to come up. I think what's
exciting is, not only did we find that the ketone pathway was
differential modified by dapagliflozin, but that it wasn't at the
level of severe ketosis that we would be concerned about. And
then secondly, we found pathways of fatty acid oxidation. Some
related to the effects of the medication and some related to
changes in functional outcome. So it really enhanced beyond what
we already knew about ketone biology, expanded our understanding
of potential mechanisms of SGLT2 inhibitors, and expanded this
into the HFrEF space, Carolyn.


Dr. Carolyn Lam:


Oh, that's so nice. I'm bursting with questions, but I really,
really have to ask Dr. Manuel Mayr, first, could you put these
findings into context for us and tell us what they mean
clinically?


Dr. Manuel Mayr:


Yeah, Carolyn. First of all, I want to join you in congratulating
the authors to this important study. As Svati mentioned, previous
studies have reported effects of SGLT2 inhibitors on ketone
bodies, but the present study really adds to the literature
because it uses the state of the art metabolomic techniques. It
uses a technique called mass spectrometry, but they also have a
rating of, I think, in total, 63 metabolites in over 200
patients. Mass spectrometry is becoming increasingly important
for cardiovascular precision medicine because we can use it in
clinical trials to provide an unbiased assessment of metabolites
and proteins. So it's a very versatile technology. I think this
study really adds to the rapidly growing literature that SGLT2
inhibition is a principle of unloading the failing heart from
metabolic stress.


Dr. Carolyn Lam:


Wow, I really like that and your editorial is just beautiful. I
love that you say, "After the serendipitous findings of improved
heart failure outcomes with SGLT2 inhibitors, mechanisms were
postulated, but studies, such as the one we're discussing, are
needed to really uncover what's the real thing." Now, I know this
may sound really oversimplified and so on, but I'd really love
for Senthil or Svati to just bear with me as I ask, what are you
going to say to people who go, "Okay, then we should just be
downing ketones," Or, "We should be Working on the fatty acid
parts of it," Or taking conclusions like that. What would you say
to something like that?


Dr. Senthil Selvaraj:


I'm happy to go first. It's a really wonderful question and I do
think that this study raises the question of whether we should be
exogenously increasing ketone levels to provide some sort of
benefit. I would say the jury's still out there. I think it's a
hot topic right now. But there are also differences between how
we raise key tone levels, whether you do that endogenously in the
body, or whether you give something like a ketone supplement, so
exogenous ketone supplementation. And I think that there are
completely different physiologies there. So more to come. I think
there are a lot of studies in this space.


The ketogenic diet is something that I'm often asked as well,
whether that might provide benefit to heart failure. There are a
lot of ways that I can, but one thing that we need to be mindful
of is the fact that it will reduce glycogen stores as well, which
may impact exercise capacity. So, we need more data. I would say
the other thing that we found in our studies, while they were
increased in ketone levels and markers of fatty acid oxidation
with dapagliflozin treatment, we aren't necessarily sure that
those mediate the benefits of SGLT2 inhibitors. DEFINE has
important clinically relevant endpoints, but it is not an
event-based trial. And so we don't know and we can't link the
changes in metabolites with changes in outcomes quite yet.


Dr. Svati Shah:


Carolyn, just to add to the wonderful response that Senthil just
gave, I think we do have to be careful. We don't know whether
these are direct effects of SGLT2 inhibitors or whether these are
related to the caloric loss that we know happens with these
medications. I think it's important to point out that we're
looking in the blood, we don't actually know what's happening at
the tissue level, so we do have to be a little bit careful. We
have made inferences that this is reporting on substrate fuel
selection in the heart, but we also suspect that skeletal muscle
and other organs are heavily involved in some of the pathways
we're seeing. So I just wanted to make those important caveat to
the epidemiologic work that we do.


Dr. Carolyn Lam:


And those are so important, so thank you Senthil and Svati.
Manuel, I'd love to invite your thoughts because you did sort of
point out some of these points in your editorial. Could you maybe
discuss a bit of those and raise any questions, perhaps?


Dr. Manuel Mayr:


Yes. I think Svati and Senthil have nicely mentioned already that
these measurements are performed in plasma. So the changes in
plasma could be due to, for example, increased production in the
liver due to decreased consumption in other tissues. So I guess
the next step would be, and I would be really interested on what
the authors want to pursue, is to provide direct evidence for the
energetic hypothesis, that really the heart is consuming these
keto bodies and what type of measurements could be performed to
provide direct evidence in humans for these metabolic hypothesis.


Dr. Senthil Selvaraj:


That's a really great question, Manuel. There was a really nice
study that was published about a year or two ago in Science in
which the authors did coronary sinus sampling. So really to get
arterial venous gradients, measure substances in the arterial
system as well as the coronary sinus venous system and get
extraction. I think that that study would be very interesting to
understand. You take patients on SGLT2 inhibitors, those who are
not, and to understand what is the heart chewing on. Obviously
more invasive than some other approaches, but other studies that
I think would be really interesting in those space would be flux
studies and stable isotope studies. Again, as Svati really nicely
mentioned, these are systemic physiology snapshots whenever we do
less localized techniques like that, but they're still very
important because heart failure is a systemic process.


Dr. Carolyn Lam:


Anything to add, Svati?


Dr. Svati Shah:


No, I think you said it beautifully. I'll just say on the sort of
epidemiologic side, to be able to link this to harder outcomes,
DEFINE-HF wasn't really designed to be able to do that. So as we
expand our understanding of SGLT2 inhibitors, understand
different populations, and to link these pathways to more
objective outcomes, I think, will be really useful, also.


Dr. Carolyn Lam:


Indeed. Manual, in your editorial, you actually discuss some of
your own work, which may be the ones that Senthil is actually
talking about. What is your view?


Dr. Manuel Mayr:


Well, I think I'm very excited that beyond fatty acid metabolism
and glucose metabolism, ketones have extracted increasing
attention. Ketone body metabolism, I think, has long been
underappreciated. We still need to understand to what extent it
really acts as a fuel and that it can help to overcome the energy
deficit that creates heart failure. I think, as mentioned by
Svati and Senthil, we need more studies in this area, and of
course other trials are ongoing where they're going to measure,
for example, the phosphocreatine to ATP ratio by using
phosphor-NMR spectroscopy. So we get direct evidence whether
there really is an energetic improvement upon SGLT2 inhibition. I
think this will be studies to look forward to and to add to the
growing literature that metabolism is important as a therapeutic
target for heart failure.


Dr. Carolyn Lam:


Oh, such exciting times. You mentioned the EMPA-VISION trial in
your editorial. I think I'm trying to tell everybody, you have to
pick up the paper and the editorial. You're going to learn so
much. This is so cool. Thank you so, so much all of you for being
on this podcast, for sharing your thoughts. I'm sure everyone has
learned a lot and enjoyed it just as I have. On behalf of Greg
and I, thank you for being here, thank you for joining us today,
and don't forget to tune in again next week. Thank you.


Dr. Greg Hundley:


This program is copyright of the American Heart Association 2022.
The opinions expressed by speakers in this podcast are their own
and not necessarily those of the editors or of the American Heart
Association. For more, please visit ahajournals.org.