Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. And Dr. Carolyn Lam, Associate Editor from the National Heart Center, and Duke National University at Singapore.
What is the effect of obesity and underweight status on perioperative outcomes of congenital heart operations?
Our feature paper this week sheds light from the Society of Thoracic Surgeons Database. More soon, right after these summaries.
The first original paper highlights the role of micro RNAs in metabolic remodeling and heart failure. As a reminder, micro RNAs are small, noncoding RNAs important in post transcriptional modification and influencing many cellular processes simultaneously.
First author, Dr. Heggermont, corresponding author, Dr. Heymans, and colleagues from Maastricht University in the Netherlands use mice subjected to pressure overload by means of endotension to infusion or transverse aortic constriction. They show that micro RNA 146A was up regulated in whole-heart tissues in these murine pressure overload models, as well in left ventricular biopsies of aortic stenosis patients. Over expression of micro RNA 146A in cardio cardiomyocytes provoked cardiac hypertrophy and left ventricular dysfunction in vivo, whereas genetic knockdown or pharmacological blockade of micro RNA 146A blunted the hypertrophic response and attenuated cardiac dysfunction in Vivo.
Mechanistically, micro RNA 146A reduced its target dihydrolipoyl succinyltransferase or DLST, a mitochondrial protein that functions as a TCA cycle transferase. DLST protein levels were reduced in pressure overload mice, while they were partially maintained in micro RNA 146A knockout mice. Furthermore, overexpression of DLST in wild type mice, protected against cardiac hypertrophy and dysfunction in Vivo. Thus, micro RNA 146A and its target DLST are important metabolic players in LV dysfunction. These results also opened the door to novel therapies to treat metabolic disturbances and improve energy efficiency of a failing heart.
Program cell death is critically involved in ischemic cardiac injury, pathologic cardiac remodeling, and heart failure progression. Our next paper sheds light on the regulatory mechanisms of necroptosis and its significance in the pathogenesis of heart failure. Using genetic mouse models, first authors Dr. Guo and Yin, corresponding author Dr. Liu, and colleagues from University of Washington in Seattle, identified a critical role for a tumor necrosis factor receptor associated factor 2 or TRAF2 in myocardial survival and homeostasis by suppressing necroptosis.
The authors delineated an important TRAF2 mediated NF-KB independent pro-survival pathway in the heart by suppressing necroptotic signaling. They identified novel molecular mechanisms whereby TRAF2 suppressed TNF receptor 1 mediated, receptor interacting protein 3 dependent necroptosis, which is critical for myocardial survival and homeostasis. Thus, this finding suggests that the necroptosis suppressing TRAF2 signaling pathway and its effectors may serve as novel therapeutic targets for pathologic cardiac remodeling and heart failure.
Our next paper tells us that cerebral hyperperfusion may be associated with accelerated cognitive decline and an increased risk of dementia in the general population. First author Dr. Walters, corresponding authors Dr. Ikram, and colleagues from Erasmus University Medical Center in Rotterdam, The Netherlands, measured cerebral blood flow by 2D phase contrast MRI in non-demented participants of the population based Rotterdam study. A 4,759 participants with a median age of 61 years, and a median follow up of 6.9 years, 123 participants developed dementia.
Lower cerebral perfusion was associated with higher risk of dementia and this risk was even higher with increasing severity of white matter hyperintensities on MRI. At cognitive reexamination after an average of 5.7 years, lower baseline perfusion was associated with accelerated decline in cognition, which was similar after excluding those with incident dementia, and again, most pronounced in individuals with higher volumes of white matter hyperintensities.
Thus, lower cerebral perfusion was associated with accelerated cognitive decline and increased risk of dementia in the general population. This association was modified by hypertension and cerebral small vessel disease, possibly reflecting impaired arteriola and capillary function. This paper calls for further long term study and evaluation of optimizing cerebral perfusion as a means to prevent cognitive deterioration, for example, in patients with heart failure or carotid artery stenosis.
Well, that wraps it up for our summaries. Now for our feature discussion. For today's feature discussion, we will be looking at data from the Society of Thoracic Surgeons Database. This time looking at the effect of body mass index on perioperative outcomes of congenital heart operations in children, adolescents, and young adults. To discuss this, we have none other than the first and corresponding author, Dr. Michael O’Byrne from Children's National Medical Center in Washington D.C., as well as Dr. Naveed Sattar, Associate Editor from University of Oxford. Welcome gentlemen.
Dr Michael O’Byrne: Good morning.
Dr Naveed Sattar: Good morning.
Dr Carolyn Lam: Michael, we know that extreme body mass indices, very high or very low, has been associated with increased risk of at first, perioperative outcomes in mainly older adults undergoing cardiac surgery. We also know about the obesity paradox in conditions like heart failure, so why was it important to look at this specific group of patients? Congenital heart patients and children, adolescents, and young adults?
Dr Michael O’Byrne: Yeah, I think that as a pediatric cardiologist, a lot of the data that we use to guide our management is extrapolated from adult studies. However, in this particular case, it wasn't clear necessarily that adult data would necessarily be applicable to children and adolescents and young adults. We are aware that there are epidemiologic trends that congenital heart disease population ages and there are also in increasing problems of obesity among children in the United States.
The convention wisdom among surgeons in the United States is that obesity would increase perioperative risk and the thought is that some combination of exposure to hypertension and diabetes and peripheral vascular disease might impede wound healing and that body habit as itself might be a risk for the technical approach in wound healing. Acknowledging that there's a lot of evidence both for extreme BMI being a risk in surgical patients and adults, but also the idea that obesity paradox might be important in children because the biological mechanisms might be different.
Children themselves are exposed, their sort of dose response or dose exposure is less, they're younger, and so haven't been obese for a prolonged period of time, so that the integrated effect of having diabetes, hypertension, and obesity might be less. At the same time, we also acknowledge that in children with heart disease, we have congenital cardiac disease, the same issues with cachexia and frailty are present. i.e. that children with very low body mass index might be assigned to their own medical frailty, or a part of a heart failure cachexia syndrome.
One of the challenges in dealing with children with congenital heart disease, however, as you know is that its rarer than cardiac disease of the aging and additionally, that the population is very heterogenous in terms of the actual defects that are present and the surgeries that are performed. It was relevant to look and see over a wide range of sort of technical complexity surgeries with a wide range of sort of intrinsic preoperative risk of perioperative outcome, whether or not BMI would be associated with an adverse outcome. Either operative mortality in this case, or a composite outcome of mortality, major adverse events, and wound infection.
Dr Carolyn Lam: Wow, that makes a lot of sense and congratulations. This is not just the first, it's huge and really comprehensive. Could you just tell us a little bit more about what you did and what you found?
Dr Michael O’Byrne: I think as this point, I'd have to acknowledge that the challenges that we described in terms of both a sample size and in terms of getting a representative sample, is a constant challenge in our field and we have to give credit to my co-authors Marshall and Jeff Jacobs for their work in developing the collaboration that allowed for the STS Congenital Heart Surgery Database to exist. Also, on top of shepherding the database, their research, along with the people at Duke Clinical Research Institute, they've developed a robust risk stratification model for mortality that we utilize as part of this study. Without that, this would be really be very challenging.
What we did is performed an observational cohort study using the STS Congenital Heart Surgery Database to look at the risk of perioperative mortality and composite outcome in patients undergoing surgery in the United States between 2010 and 2015. We looked at both the actual events, the sort of observed events, in terms of mortality and adverse events, and then created multivariate models to adjust for the known covariance.
We hypothesized that extreme BMI, either very high or very low, would be associated with increased risk of mortality and increased risk of that composite outcome. What we found that operative mortality and that perioperative adverse events occurred more frequently in obese and severely underweight subjects. However, because they have an unequal distribution of potentially important covariance, we used multivariate modeling to adjust for those covariance.
Our multivariate models for death, however, the severely underweight subjects had an odds ratio of 1.4 and obese subjects had an odds ratio of 1.3, but neither was specifically significant in that context. We sort of anticipated that with a possibility given the very low event rate. That's the reason we've used a composite outcome, a higher event rate.
For that composite outcome, in both different versions of the multivariate model that we used, the severely underweight subjects had an odds ratio of 1.5, underweight subjects had an odds ratio of 1.3, and obese subjects had an odds ratio of 1.2. An increased risk in all three of those populations of interest relative to normal weight or just overweight subjects.
Dr Carolyn Lam: We're always saying that at circulation we do want to publish papers that have direct and important clinical implications, so Naveed, could you share some thoughts on what this means clinically?
Dr Naveed Sattar: Yeah, I think they went through the review process and I think the paper was very well written. I think Michael and his colleagues clearly understood the strength and the limitations of the data so that you can only ever itself prove associations here and therefore, clinically when we push them on trying to make clinical inferences, I think clearly they recognize that once they find associations between obesity and adverse outcomes and underweight.
What they need to do next, now this is a paper that then leads you to think, "Well actually, I need to do some clinical trials to prove that module ..." You're preventing these outcomes or in very under knowledge where they're actually increasing the BMI but improving their nutrition, cannot also improve outcomes following surgery. Now those are tough things to do. Michael, what do you think from some of the clinical inference? My inferences were the associations were there, particularly for the normal [inaudible 00:12:35] outcomes, but actually to prove that, to make a difference, you probably might need to do some intervention trials or is that how you take it as well?
Dr Michael O’Byrne: I agree with you 100%. I think that as an epidemiologist, I think that what we see in an observational study like this is an association. The two next levels of research that are necessary at this point are to see whether or not in this population BMI is a modifiable factor in the short run before surgery, or even in the long run. And the second question to answer is whether those adjustments in BMI, if they are achievable, affect outcome with surgery. Absolutely.
It's a tremendous challenge, both logistically in organizing a study, and honestly, in terms of capturing a cohort that would be large enough, given that this is almost 100% of the surgeries that occurred over a six year period in the United States.
Dr Naveed Sattar: I looked at it and thought, "Well, the mortality association once you adjusted were not quite significant but are there any individuals you would not do surgery on based on their BMI based on these results?
Dr Michael O’Byrne: The motivation for the study is exactly to try to begin to shed light on that kind of question. I think that it might be what I would call a tiebreaker potentially, if you have a situation where a patient is near meeting criteria but isn't quite at a place where you need to do surgery at that point. It might dissuade you from proceeding immediately potentially pursuing a course that might adjust their BMI in the correct direction.
At the same time also, in a patient who's underweight particularly to evaluate whether their medical regimen has been optimized and if there are other residual lesions that can be addressed in a non-surgical or medical fashion.
Dr Naveed Sattar: I suppose the other trick with this type of research research is always trying to make sure that people understand these are the associations and not trying to attribute causality because it's always physical, isn't it? But I think you and your team did that very well and I'm sure we had a back and forth with review but I think your discussion section, your limitation section, is beautifully written and covers those kinds of caveats, which I think is important as well.
Dr Michael O’Byrne: I thank you for that. That's very complimentary and we certainly strived for that, but I think that you as an editor, and also in terms of the reviewers also, were very helpful in that sort of collaborative process to try to make sure that we're communicating it. It's not always clear in a project that takes months and years to finish when you're writing it necessarily, you may be constantly aware of trying to be clear in your communication but it's also helpful to have a reviewer from the outside carefully read the study.
Dr Carolyn Lam: That's wonderful and Michael, may I just join Naveed in congratulating you on beautiful paper? And maybe just one other little question, did you have any insights into the mechanisms of increased risk for composite events in the extremes of BMI?
Dr Michael O’Byrne: I think it's an important question. There's been a tremendous amount of research in adult cardiac disease about whether it is the BMI as a steady state or BMI changes immediately before and after surgery that are relevant in this case. From this kind of observational study, it's very hard and very challenging to try to make any sort of inferences about the causes. It would be an important part of any study moving forward to include ways to investigate that, and honestly, as an interventional cardiologist and epidemiologist, I probably would defer to Naveed, he might have more cogent and logical ideas about that than I do.
Dr Naveed Sattar: We've had lots of research from a whole variety of researchers. We all understand it's finally serious but recognize it's difficult, so one of the ways moving forward and I think Michael and his colleagues have this is if you have serial BMI data prior to surgery, that could try and inform on reverse causality because of the low BMI, but in terms of the mechanisms, remember these are associations, but I think mechanisms are well covered if you are obese and clearly you have risk factors for death, across the vasculature, across the cardiac functions, across the whole variety of things.
We know those mechanisms, question is, to what extent are they actually operating and causing increased risk in the surgical arena and that's a really tough ask. I think people can come up with a multitude of mechanisms. I think the key things, like this particular paper, is that there are potential mechanisms but these are associations ... Look, this is what we found, and clinically now we need to try and address this within the following types of interventions or at least provide some guidance to colleagues and clinicians.
Exactly as Michael says, if there is somebody who is approaching surgery whose quite obese, perhaps they should try and intervene to try and lessen their weight for a short period of time prior to [inaudible 00:17:07], you know what happens. It would be nice to do some big trials but I think doing trials in this area is going to be really tough, but with imagination, with good collaboration across centers, trials are not impossible. I think they can be done.
Dr Michael O’Byrne: Naveed, I think, actually articulated what I think is both the difficulty of doing that trial but also the importance of it. I think that looking at ... In these databases, we don't have a serial BMI and I think that's an important missing piece of information that we tried to address in our discussion and I think it's something that would be really valuable moving forward. And certainly testing interventions, whether they're medical, interventional, or surgical, to help these patients who are obese either lose or maintain an appropriate weight is the next step.
On the converse side, this research highlighted to me the prevalence of chachectic or underweight patients in our population and it's something that outside of the infant period, we don't necessarily think about tremendously and we don't think about it as a modifiable factor. I think that's another group of patients who also deserve some attention.
Dr Carolyn Lam: Listeners, you've been listening to Circulation on the Run. I'm sure you learned a lot as I did. Don't forget to tune in again next week.
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. Our podcast today highlights an important perspective piece on charting a future together and turning discovery science into cardiovascular health. You don't want to miss this, coming up right after these summaries. The first original paper tells us about the importance of changes in exercise capacity following transcatheter aortic valve replacement or TAVR.
First author, Dr. Altisent, corresponding author, Dr. Rodés-Cabau, and colleagues from Quebec Heart and Lung Institute in Canada studied a total of 305 patients undergoing TAVR with baseline and six month followup exercise capacity assessments by six minute walk tests. They found that close to one-third of patients undergoing TAVR failed to improve their exercise capacity despite an optimal hemodynamic result post-procedure.
Factors associated with a lesser exercise capacity improvement included patient characteristics such as older age, female sex, non-cardiac comorbidities, such as chronic obstructive lung disease, peripheral artery disease and bleeding episodes resulting in reduced hemoglobin levels. Importantly, the absence of an improvement in physical performance at six months post-TAVR was an independent predictor of mortality and adverse cardiovascular outcomes during the ensuing four years and particularly among patients with a greater impairment of exercise capacity pre-TAVR.
Thus, implementing exercise capacity assessment pre and post-TAVR may help to improve patient risk stratification and augment the accuracy of the prognostic information given to patients, helping to identify those requiring more intensive followup assessment. The next study provides mechanistic insights into the adverse health outcomes associated with particulate matter exposure in the air. First author, Dr. Lee, corresponding author, Dr. Kahn, from Fudan University in Shanghai, China and colleagues conducted a randomized double-blind crossover trial in 55 healthy college students in Shanghai. Real and sham air purifiers were placed in participant's dormitories in random orders for nine days with a 12 day washout period.
Serum metabolites were quantified using gas chromatography mass spec and ultra-high performance liquid chromatography mass spec. They found that higher particulate matter exposure led to a significant increase in cortisol, cortisone, epinephrine and norepinephrine. Between treatment, differences were also observed for glucose, amino acids, fatty acids and lipids. They also found that higher blood pressure, hormones, insulin resistance and biomarkers of oxidative stress and inflammation were present among individuals with higher exposure to particulate matter.
Thus, this study showed that activation of the hypothalamus-pituitary-adrenal and sympathetic-adrenal medullary axis may contribute to the adverse cardiovascular and metabolic effects of particulate matter exposure in the air. In China, indoor air purification may be a practical way to reduce personal exposure to particulate matter. The next study shows that N-acetylcysteine may be new effective thrombolytic treatment. First author, Dr. Lizarrondo, corresponding author, Dr. Gauberti and colleagues from Inserm, France hypothesized that N-acetylcysteine might cleave the von Willebrand factor multimers inside occlusive thrombi, thereby leading to their disillusion and arterial recanalization.
To test this hypothesis, the authors used experimental models of thrombotic stroke induced by either intra-arterial thrombin injection or ferric chloride application followed by measurement of cerebral blood flow using a combination of Laser Doppler Flowmetry and magnetic resonance imaging. They showed that intravenous and acetylcysteine administration promoted lysis of arterial thrombi that were resistant to conventional approaches such as recombinant TPA, direct thrombin inhibitors and anti-platelet treatments. Furthermore, through in vitro and in vivo experiments, they provided evidence that the molecular target underlying the thrombolytic effects of N-acetylcysteine were principally the von Willebrand factor that crosslinked platelets in arterial thrombi.
Co-administration of N-acetylcysteine and a non-peptidic GP2B3A inhibitor further improved its thrombolytic efficacy essentially by accelerating thrombus disillusion and preventing rethrombosis. In a new large vessel thromboembolic stroke model in mice, this co-treatment significantly improved ischemic lesion size and neurological outcomes. Importantly, N-acetylcysteine did not worsen hemorrhagic stroke outcome suggesting that exerted thrombolytic effects without significantly impairing normal hemostasis. Thus, in summary, N-acetylcysteine was shown to be an effective and safe alternative to currently available anti-thrombotic agents to restore vessel patency after arterial occlusion.
The clinical implications of the study are wide reaching considering the very wide availability, low cost and apparent safety of N-acetylcysteine. This is discussed in an accompanying editorial by Dr. Lillicrap from Queens University, Kingston, Canada. The final study identifies a novel mechanism for regulation of cardiac fibrosis that revolves around plasminogen activator inhibitor type 1 or PAI-1. First, author, Dr. Flevaris, corresponding author, Dr. Vaughan and colleagues of Northwestern University, Feinberg School of Medicine in Chicago, Illinois showed that cardiac fibrosis was detected by late gadolinium enhancement cardiac MRI in two otherwise healthy humans with complete PAI-1 deficiency due to a homozygous frameshift mutation in serpene 1.
They further performed a series of mouse experiments to show that treatment of young PAI-1 deficient mice with angiotensin 2 induced extensive hypertrophy and fibrotic cardiomyopathy. Ventricular myocytes were found to be the important source of cardiac transforming growth factor beta or TGF beta and PAI-1 regulated TGF beta synthesis by cardiomyocytes in vitro as well as in vivo during cardiac injury. PAI-1 deficiency significantly enhanced multiple TGF beta signaling elements and transcriptional targets. Thus, in summary, this study show that PAI-1 is an essential repressor or cardiac fibrosis and access a molecular switch that controls the cardiac TGF beta access and its early transcriptional effects that lead to myocardial fibrosis.
Modulation of the cardiomyocytes TGF beta access represents a unique therapeutic strategy that may abrogate fibrotic signaling and cardiac fibrosis. Well, that wraps it up for your summaries. Now for our featured discussion. We are incredibly privileged today to have the director of the National Heart, Lung and Blood Institute, Dr. Gary Gibbonss with us on the podcast, as he talks about his perspective piece entitled "Charting Our Future Together: Turning Discovery Science into Cardiovascular Health." Also, joining me today is our editor in chief, Dr. Joseph Hill from UT Southwestern. Joe, I know you share my incredible excitement and enthusiasm at having Dr. Gibbonss on this podcast with us.
Maybe could I invite you to say a few words to frame just how important this perspective piece is for Circulation?
Dr. Joseph Hill: We all know that cardiovascular medicine and science are evolving at an unprecedented pace. The challenges we face are evolving and yet the opportunities and the tools and the resources at our disposal are unprecedented in their scope and vision. We're very pleased that Gary has provided strong leadership at NHLBI now for several years and has laid out in this perspective piece here where he thinks the next steps are specifically around this strategic vision that focuses on precision medicine and data science. I would love to hear Gary provide additional perspective on that vision.
Dr. Gary Gibbons: Well, thank you, Joe. As the director of NHLBI, clearly we're public servants and we're accountable stewards of the nation's investment in heart, lung and blood and sleep disorders. This piece gave us an opportunity to outline some of the opportunities that lay ahead in a strategic visioning process. First, I should note that a key part of the legacy of the NHLBI is to make strategic investment with enduring principles in mind to really support investigator initiated discovery science as really the core foundational element of our research portfolio, as well as to maintain a balance portfolio to really expands to spectrum of basic translation clinical population and implementation science.
In this piece, we particularly want to highlight our strategic visioning process in which we encourage the broad input of the NHLBI community that actually included over 4,000 participants in this process from every state in the country. Indeed, 42 countries around the world to provide the most compelling questions and critical challenges that the field faces around strategic goals of understanding normal human biology, reducing disease, accelerating translation and preparing a biomedical workforce and resources for the discovery science of the 21st century.
Out of that strategic vision, we focus in on two elements that emerged that relate it to precision medicine and data science for this piece and really that was the central core of what we wanted to share with the Circulation readership about how these two areas we think are going to be transformative in the years ahead.
Dr. Carolyn Lam: Dr. Gibbons, you know, when the term precision medicine is used, sometimes it's a bit fuzzy I think in the minds of a lot of people. Could you maybe give a few examples or perhaps a specific idea that comes to mind?
Dr. Gary Gibbons: You're right. There's often a lot said about it than probably a bit of hype about it. In some ways you could see this as a legacy of cardiovascular medicine and science. It could be argued that the definition of cardiovascular risk factors that came out of the Framingham Heart Study many years ago was the first sort of forerunner of precision medicine. It helped us indeed define those individuals who are at the greatest risk of having a heart attack and that to this day has played a role in directing targeted preventive treatments of the highest risk individuals in order to prevent heart attacks. That has continued to evolve.
I think what's new now is that we have, as Dr. Hill mentioned, new modalities of both imaging and analytics of computational science, as well as novel biomarkers and genetic markers that can help us be even more precise in that risk assessment. That's really I think the greater opportunity to further subcategorize patient populations to get the right drug to the right patient at the right time with a more strategic treatment approach.
Dr. Joseph Hill: Gary, that's very exciting. I think your vision is absolutely compelling. I like how you categorize the NHLBI as a catalyst for the future. I'd like to think that the Biomedical Journals, the AHA Portfolio of Journals and Circulation are also catalysts that will partner with NHLBI and other entities to chart the course for the future. That again the challenges that we face now are different than they were back in the era when Framingham first got started after World War II. The tools that we have are also evolving rapidly and certainly our perspective from Circulation is that we are stewards of helping chart that course, helping identify and bring forth the best science around the world. In many ways we look to you as a partner.
Dr. Gary Gibbons: Oh, absolutely. The NHLBI really can't fulfill our mission of turning discovery science into the health of the nation and indeed around the world without a circle of partners and that certainly includes the platforms of disseminating new knowledge like Circulation, as well as partner organizations such as American Heart Association. We definitely appreciate the value that your organ brings to really enhancing our efforts to not only take discovery science, but make that knowledge available to practitioners and researchers and patients.
I think a key part of the 21st century is how we not only can discover and generate new knowledge, but how we can facilitate that movement of data to knowledge and from knowledge to action that actually enhances the lives of patients in the real world context. Again I believe your journal plays an important role in helping to do that.
Dr. Carolyn Lam: You both mentioned critical challenges that we're facing and will face. The Chinese for these challenges or crisis, the word is actually wéijī. Okay? Wéi is actually meaning danger, whereas jī is for jīhuey which is opportunity. In every challenge, there's always this new opportunity and I just really would like to ask what are the greatest challenge and perhaps the greatest opportunity?
Dr. Gary Gibbons: I think the challenge that we probably face is the emerging epidemic of non-communicable diseases typically cardiovascular disease throughout the world. Not only in the most industrialized nations, but indeed mainly the developing nations. This will quickly surpass communicable infectious diseases as the major burden and causes of mortality worldwide. We're dealing with a global challenge. Increasingly, we recognize that scientific discovery and analysis is often siloed in various packets. Our vision for the future is really to promote the creation of a global reach of what we're calling a Data Commons. That is that a disease has no borders. Science should not be limited to national states.
It is part of the commonwealth if you will of information and knowledge that really should transcend national borders. We say this is a global community of data and information and knowledge exchange and collaboration. As part of this global community, it's that we think this diverse and inclusive approach will be critical to the best minds and best practitioners of the world learning from each other and contributing to this commonwealth of knowledge. We're excited because the opportunity on the other side of that challenge is that it's an unprecedented capability of power to communicate now. We I think are communicating with you from Singapore and we're in a digital age in which this notion of communication and knowledge exchange should be more fast than it's ever been before.
Indeed, we can create computer platforms that are similar to what exist for a Facebook or a Google that are global in scope. The vision is really to say what would happen if we could turn that toward biomedicine and make biomedicine part of this data science such that we have global contributions to our understanding, knowledge exchange and really create that sort of global sandbox if you will of knowledge exchange and discovery. That's part of this notion of creating a Data Commons and really advancing data science as an element of a strategic vision.
As we move forward with precision medicine and data science, our most sacrosanct stewardship is for the next generations. A critical element is to ensure that we're providing them with the tools and training to really lead the charge of advancing these exciting areas of science and that indeed will be a global enterprise.
Dr. Joseph Hill: That's very exciting, Gary. I take my hat off to you for the leadership that you have maintained at the NHLBI during these times that are once very challenging and at the same time exhilarating. I look forward to working with you through our journal and partnering with you to bring to fruition much of what you had laid out in your vision.
Dr. Gary Gibbons: Thank you, Joe. We look forward to our ongoing partnership.
Dr. Carolyn Lam: Thank you, listeners, for joining us today. Do join us again next week.
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.
Later on in this podcast, we will be meeting Dr. Nancy Schweitzer, Editor-in-Chief of the new Circulation Heart Failure. We will be discussing today's feature paper on acute myocarditis as well as hearing about her visions for the journal. All that coming right up after these summaries.
The first original paper this week suggests that day-to-day blood pressure variability may be a significant risk factor for dementia. First author Dr. Oishi, corresponding author Dr. Ohara, and colleagues of Kyushu University from Fukuoka, Japan, studied a total of 1,674 community-dwelling Japanese elderly without dementia, who were followed up for five years, and had home blood pressure measured three times every morning for a median of 28 days.
They found that the age and sex adjusted incidences of all-cause dementia, vascular dementia, and Alzheimer's disease increased significantly with increasing day-to-day variability of home systolic blood pressure. These associations remained unchanged after adjusting for potential confounding factors, including average home systolic blood pressure. The study, therefore, suggests that the measurement of day-to-day blood pressure variability, using home blood pressure monitoring, may be a useful way to assess future risk of dementia, irrespective of dementia subtype.
The next paper is one of the first studies to directly target a gene within the fibroblast of a mammalian heart and show a direct role in regulating cardiac fibrosis. Co-corresponding authors Dr. Molkentin from Howard Hughes Medical Center and Cincinnati Children's Hospital Medical Center and Dr. Davis from University of Washington and colleagues performed an elegant series of mouse experiments to show that the gene-encoding p38 alpha mitogen-activated protein kinase was required to mediate fibroblast activation in the mouse heart following injury.
They also showed that forced activation of p38 within fibroblasts, using a transgenic approach, was sufficient to drive fibrosis in multiple tissues of the mouse, including the heart.
In totality, their findings indicated that p38 mitogen-activated protein kinase was a nodal signaling effector within the cardiac fibroblast that drove both wound healing and long term fibrosis in heart failure. In other words, it appears to play a crucial role in the control of both physiological and pathological processes. The clinical implications are that pharmacologic inhibition of p38 mitogen-activated protein kinase in heart failure could reduce progressive fibrosis. However, the same inhibition during acute myocardial infarction injury may inhibit wound healing and be detrimental. These issues are discussed in an accompanying editorial by doctors, Stratton, Koch and McKinsey.
Receptors, well known for their roles in angiogenesis and cancer, may play a role in atherosclerosis, as shown in the next paper, which looked at the Eph-family of receptor tyrosine kinases. These are the largest family in the mammalian genome, which interact with ephrin ligands on adjacent cells to mediate cell adhesion repulsion signaling.
First author, Dr. Finney, corresponding author, Dr. Orr, from LSU Health Sciences Center, Shreveport, and colleagues assessed the role of EPHA2 in atherosclerosis by deleting the EPHA2 in a mouse model of atherosclerosis and by assessing EPHA2 function in multiple vascular cell culture models.
The authors identified a novel role for EPHA2 in atherosclerosis by regulating both plaque inflammation and progression to advance atherosclerotic lesions. Cell culture studies suggested that endothelial EPHA2 contributed to atherosclerotic inflammation by promoting monocyte firm adhesion, whereas, smooth muscle EPHA2 expression regulated the progression to advanced atherosclerosis by regulating smooth muscle proliferation and extracellular matrix deposition.
The clinical implications are that blunting EPHA2 ligation may selectively reduce plaque-associated inflammation. Since the effect of EPHA2 on smooth muscle proliferation appears to be largely ligand independent, unlike its effect on inflammation, the blunting of EPHA2 ligation may limit inflammation while leaving smooth muscle fibroproliferative remodeling intact.
Well, that wraps it up for our summaries. Now, let's go to our feature discussion.
Our feature paper today may cause us to think a little bit differently about fulminant versus non-fulminant acute myocarditis because the findings are actually in contrast with previous studies and are extremely insightful.
And, to discuss this, I am so pleased to have the corresponding author, Dr. Enrico Ammirati from Niguarda Hospital in Milan, Italy, as well as Dr. Nancy Sweitzer, Associate Editor of Circulation from University of Arizona, who managed this paper. But importantly, also, the Editor In Chief of Circulation Heart Failure. Welcome, Enrico and Nancy.
Nancy: Thank you, Carolyn.
Carolyn: Enrico, could I ask you to start by clarifying the conditions that we're talking about here? When we say acute myocarditis or fulminant myocarditis, and non-fulminant myocarditis, what exactly are we referring to?
Enrico: We refer to an acute condition and fulminant myocarditis is a myocarditis inflammation of the myocardium that's a media anatomic or mechanical support due to an anatomic instability, while non-fulminant myocarditis it's a condition where the patient remains hemodynamically stable. Previous records have suggested that despite their dramatic presentation of patient with a fulminant myocarditis might have better outcome than those with acute fulminant myocarditis.
Now in this study we have over 55 patients with fulminant myocarditis and in particular, 34 patients with fulminant myocarditis with viral genomes within two weeks from the onset of symptoms, whereas in the previous record, in particular from [inaudible 00:07:38] we have shown in 15 occasions of fulminant myocarditis, that fulminant myocarditis as quite a good prognosis.
But what we believe it is that gives disparity between our results that connected all acute patients admitted to the emergency department with [inaudible 00:08:01] and symptoms onset within one month to two weeks before. Is the main difference comparing [inaudible 00:08:11] this study [inaudible 00:08:13] patient with onset of symptoms since one year before the onset of symptoms. And we believe that we enroll acute patients.
Whereas in the other study, there was sort of selection by us. It was true that in those previous studies, they have all just patients who we were endomyocardia biopsied performed whereas in our study we did not perform endomyocardia biopsies in that case. But we feel that we have a snapshot of the acute stage of a fulminant myocarditis, so we connected all the patients, whereas in previous study, maybe some of the patients they had acute symptoms died before evaluation from the other researchers.
Carolyn: Indeed, it makes a lot of sense that there may be some survival bias involved. For example, if the sickest patient didn't get a biopsy, for example.
Nancy, when you were managing this paper, what were the kind of the discussions that occurred at the editorial discussions?
Nancy: I think that Dr. Ammirati pointed it out really well. The editors felt that this was a very important paper because it really looked inclusively at myocarditis in the modern era, and showed us where perhaps bias in prior studies had led us astray in terms of our beliefs about, particularly the outcomes in this syndrome. Not only the outcomes in the fulminant patients, who have a very profound and important early mortality risk, but also the outcomes in the non-fulminant patients, who in this study, really do extremely well and do not progress to LV dysfunction, which has been a long-held belief, I think. So understanding much better the full spectrum of myocarditis was made much easier because of the comprehensive look Dr. Ammirati and his colleagues took.
Carolyn: Enrico, I do congratulate you on a beautiful paper. As I said, as a heart failure cardiologist myself, it has changed my thinking. Could you maybe share just a bit more details of what your study found and how this is important clinically?
Enrico: What we have found it is that hospital deaths or heart transplantation was about 25 percent in fulminant myocarditis compared to ten percent in non-fulminant myocarditis and despite greater improvement in the left ventricle injection fraction [inaudible 00:10:56] in fulminant myocarditis compared to non-fulminant forms. The proportion of patients with the left ventricle injection fraction below 55% [inaudible 00:11:09] was higher in fulminant myocarditis comparing it to non-fulminant myocarditis. So we have to pay great attention to do this form of myocarditis not thinking that this is a condition that can simply recover with time but we have to aggressively manage this condition, and we have to see about trials designed [inaudible 00:11:39] in this specific setting to improve the [inaudible 00:11:50] outcome and to reduce myocardial injury during the acute phase.
Carolyn: True. And Nancy, I mean you see tons of these patients too. How has this impacted you?
Nancy: It's interesting, it definitely has impacted me. I like everyone, taught and taught on my teaching rounds for many years that the fulminant patients we were seeing, despite how ill they were, would have better outcomes than those who were non-fulminant. And also, many patients who present with dilated cardiomyopathy who are non-ischemic are told after searching for some viral illness in the year prior to their presentation that probably they had a virus attack the heart or an inflammation of the heart. I've stopped saying those things, and I continue to see review of papers that I'm handling about myocarditis refer to these misconceptions. So I think this is going to be a really important paper, and clarifying our understanding of how this disease evolves over time.
Enrico: I fully agree, I fully agree with this message, and [inaudible 00:12:54] but I believe that the traditions that are involved in [inaudible 00:13:00] maybe can be misleading for other cardiologists.
Carolyn: Nancy, I'm gonna switch tracks a little bit, I mean your explanation of that already gets me so excited about the kinds of papers that are gonna get to be seen at the new Circulation Heart Failure under your leadership. So could you just tell us a little bit more about your vision as editor-in-chief.
Nancy: Well Carolyn, Circulation Heart Failure is an excellent journal Dr. [inaudible 00:13:33] has stewarded it beautifully in its first decade of life. In many ways I don't want to change the journal, I want the very best science that's helping us have a deeper understanding of the disease processes and therapies that affect our patients. That said, I would say we have a couple new initiatives, or sort of slight differences in how we're going to manage the journal going forward. I must say, the content we get is spectacular, and we're so fortunate to be able to look through the papers we get, and try to choose the very best science. It's an amazing privilege for me and the new team.
We're really interested in young investigators and those people who are starting out in their career. The emerging scientists who are producing the best heart failure science. Early in your career you might not have the weight of data behind you to merit publication and circulation proper, but we hope that with good science well thought out excellent hypotheses, Circulation Heart Failure will be an appropriate target for those emerging investigators.
We found some great pleasure in approaching young scientists at meetings, and discussing their work, and asking them to send it to our journal. And that's been great fun and we've seen wonderful yield from that. We've been getting submissions from people we've spoken to whose work we admire, and we really hope to build that part of the journal up. Hand in hand with that is an effort at building our social media presence. We're an entirely online journal. We're very interested in visually appealing content. We do have an images in case report section. And we're going to work to try to build an online community for our young investigators who may not have the money to travel internationally, but who really needed global community of heart failure research colleagues, and we hope to be a place to build that.
And finally, we're interested in some areas that maybe, are emerging or underrepresented in other journals. Areas like ... the way technology is transforming heart failure mechanical circulatory support devices, wearable devices, the other technologies we're using increasingly in our patients. And the world of pulmonary hypertension, and right ventricular dysfunction, which is sort of searching for a journal home, and we hope that we can be that journal home. And of course representing the full spectrum of therapies for heart failures including transplantation. I already mentioned mechanical circulatory support, you know, all the richness that is the evolving field of heart failure, and how we ... I think as professionals in that field think about and treat our patients a little differently than other people caring for heart failure.
Carolyn: Listeners, you just heard it right here, on Circulation on the Run.
Thank you so much for joining us this week. Tune in again next week for even more exciting news.
Dr. Carolyn Lam: Welcome to Circulation on the Run your weekly podcast summary and backstage pass to the Journal and it's editors. I'm Dr. Carolyn Lam associate editor from the National Heart Center and Duke National University of Singapore.
Our feature paper this week provides important mechanistic insights into oxidative stress and inflammation with aging. More of that soon right after the summary of this week's journal.
The first paper contributes to our understanding of the genetic and functional relevance of soluble guanylyl cyclase activity for coronary artery disease. As background, a chromosomal locus at 4q32.1 has been associated with coronary artery disease risk with genome wide significance. The locus encompasses GUCY1A3, which encodes the alpha one subunit of the soluble guanylyl cyclase, a key enzyme of the nitric oxide cyclic GMP signaling pathway.
In today's study from co-corresponding authors Dr. Kessler, and Dr. Schunkert from Munich, Germany and colleagues the authors showed that the GUCY1A3 locus has regulatory properties with the risk allele leading to reduced expression of GUCY1A3. The lead snip modulated finding of the transcription factor ZEB1 resulting in reduced expression of GUCY1A3 in carriers of the risk allele. As a consequence risk allele carriers demonstrated impaired inhibition of vascular smooth muscle cell migration and platelet aggregation after stimulation of the soluble guanylyl cyclase.
In summary, this study suggest that modulating soluble guanylyl cyclase activity or inhibiting the effects of reduced expression of GUCY1A3 may be promising therapeutic strategies for individuals with the high risk alleles of GUCY1A3.
The next paper reports the outcome associations between adding a radial arterial graft to single and bilateral internal thoracic artery grafts in the arterial revascularization trial or ART. As a reminder, ART was designed to compare survival after bilateral internal thoracic artery over single left internal thoracic artery bypass with about 20% also receiving a radial artery graft instead of a saphenous vein graft.
In the current paper, first author Dr. Taggert from University of Oxford and corresponding author Dr. Benedetto from University of Bristol in the United Kingdom and colleagues showed that the primary endpoint of ART which was a composite of myocardial infarction, cardiovascular death and repeat revascularization at five years was significantly lower in the radial artery group when compared to the saphenous vein graft group. This association was present when the radial artery graft was used to supplement both the single internal thoracic artery as well as the bilateral internal thoracic artery grafts.
In summary this post-hoc ART analysis showed that an additional radial artery was associated with lower risk for mid-term major adverse cardiac events when used to supplement single or bilateral internal thoracic artery grafts.
The next study addresses the questions of whether intensive blood pressure lowering beyond usual targets recommended by guidelines would lead to more lowering of left ventricular hypertrophy in patients with hypertension and whether reducing the risk of left ventricular hypertrophy explains the reported cardiovascular benefits of intensive blood pressure lowering.
To answer this question Dr. Soliman from Wake Forest School of Medicine in North Carolina and colleagues studied the 8,164 participants with hypertension but no diabetes from the Systolic Blood Pressure Intervention or SPRINT Trial. They showed that among SPRINT participants without baseline left ventricular hypertrophy, intensive blood pressure lowering was associated with a 46% lower risk of developing left ventricular hypertrophy compared to standard therapy. Similarly, among SPRINT participants with baseline left ventricular hypertrophy blood pressure lowering intensively was associated with a 66% greater likelihood for regression or improvement of their left ventricular hypertrophy. Furthermore, adjusting for left ventricular hypertrophy as a time-varying covariate did not substantially attenuate the effect of intensive blood pressure therapy on cardiovascular disease events.
In summary these findings add further evidence of the benefits of the intensive blood pressure lowering in patients with hypertension and suggest that these benefits go beyond reducing the hemodynamic stress on the cardiac structure. Further research is needed to understand the mediating factors and mechanisms by which intensive blood pressure lowering impacts the cardiovascular system.
Well that wraps it up for our summaries, now for our feature discussion.
We are going to talking about aging, oxidative stress and inflammation today and really taking a deep dive into potential mechanisms. I am so pleased to be here with the corresponding author of our feature paper in this week's issue. And that is Dr. Mustapha Rouis from INSERM University Paris six in France as well associate editor from University of Rochester Dr. Charlie Lowenstein.
Dr. Charlie Lowenstein: Thank you for having us.
Dr. Mustapha Rouis: Thank you very much.
Dr. Carolyn Lam: Mustapha, what inspired you to actually look at the Thioredoxin system in looking at this aging question? What were your hypotheses?
Dr. Mustapha Rouis: Actually our laboratories working on cardiovascular diseases for several years. We have been trying to understand why oxidative stress and inflammation increase with age despite the presence of a variety of antioxidant proteins in the body. So among the antioxidant proteins the Thioredoxin-1, isoform one which is a small ubiquitous incytocylic protein called our attention because it's a multi functional protein. It can exert an antioxidant role, anti-inflammatory and anti-apositic role. So therefore we wanted to know whether the increase in the oxidative stress and inflammation with age is it due or at least in part to a deficiency of Thioredoxin-1. If so is there increases due to a decrease in protein synthesis or to increase in its degradation.
For this purpose we have constituted a cohort of young and old subject, male and female. They want to focus on this particular point because this is very important point it has not been easy to achieve and we took a lot of time to sort and to keep only subject meeting our criteria. Those who we wanted to enroll consisting of people free from any history of diseases such as cardiovascular diseases, diabetes, obesity, inflammation, any kind of inflammation, cancer et cetera. In addition we wanted subject without any risk factor for cardiovascular disease except of course the age. No smoking, no hyperlipidemia and no taking any medication.
This really very hard to achieve. Then once we have enough subject we evaluate the Thioredoxin-1 using commercially available very specific kit, ELISA kit and showed that the plasma level of Thioredoxin-1 decreased significantly with age. Since it has been described for several years that Thioredoxin-1 can be cleaved at the C terminal level, the cleavage has been described to be occur after lysine at position eight. This will generate a truncated called Thioredoxin-80. We measured the plasma concentration of Thioredoxin-80 in this sample, in this same sample of the selected subject using an ELISA method developed in our laboratory because there is no commercially kit for Thioredoxin-80.
The result showed that Thioredoxin-80 increased with age therefore the decrease in the plasma concentration of the full length Thioredoxin-1 observed in the old, in the elderly is probably due to an increase in its cleavage and not to a decrease in its synthesis. Of note we observed an increase of the expression and activity of two alpha secretases ADAM-10 and ADAM-17 two enzyme responsible for the cleavage process in the peripheral blood mononuclear cells of the old subject. Our results consolidate our interpretation.
Dr. Carolyn Lam: Wow, what a beautiful set of studies that included human samples and then also included some very elegant mouse experiments. I remember the excitement among the editors when we discussed this paper. Charlie could you just share a little bit of what went on when we looked at this?
Dr. Charlie Lowenstein: First I'd like to put this study into context which is that oxidants increase during aging and it's been known for a long time that animals that have high metabolic rates have short life spans and one of the things that goes along with high metabolic rate is a lot of radical production. And since the 1950's there's been this theory, the free radical theory of aging that radicals damage cells. And so the question is, are radicals bad? What do they do in aging? And what defenses do we have against them? So that's one of the contexts of this article.
Secondly we also know that oxidants are associated with diseases. Increased oxidants during cancer, during inflammatory diseases and during atherosclerosis so that's why this study is important. It's important for two reasons. First of all there's a theory that as you age there's more radicals and radicals might actually cause part of the problem in aging. Secondly radicals are also associated with inflammatory diseases like atherosclerosis.
When the editors got this article, it was very exciting for several reasons. First of all, the short form of Thioredoxin, TRX-80 might explain why older people have more oxidative stress. Secondly this short form TRX, TRX-80 might be a new bio-marker for aging. And thirdly, the short form of Thioredoxin might help us monitor different antioxidant therapies when people have too many radicals. So for a number of important clinical reasons our editors were very excited when we received this important manuscript.
Dr. Carolyn Lam: Mustapha, what are your next steps when it comes to this?
Dr. Mustapha Rouis: Well several studies have shown that Thioredoxin-1 can reduce inflammation and can protect the body against several pathologies which has an increased interest in its use for therapeutic purpose. However its cleavage in the generation of the Thioredoxin-80, limited research work in this direction so I just remember you that the Thioredoxin-80, the truncated form in contrast to the full length Thioredoxin-1 exerts a pro-oxidant, pro-inflammatory angiogenic and carcinogenic effect. So nevertheless in order to counter these difficulties we plan to synthesize some Thioredoxin limited peptides such as catalytic site containing peptides and these peptide used it in therapy could show significant biologic activity. This peptide could lose constitute maybe an alternative to the full length Thioredoxin.
Dr. Carolyn Lam: Wow, that is exciting. Charlie, what do think is the take home message for clinicians listening to this?
Dr. Charlie Lowenstein: Scientists and clinicians all agree that an excess of radicals is bad. But there's an antioxidant paradox which is when patients take antioxidants like vitamin E, those antioxidants don't help. In a large clinical trial suggesting that vitamin E and other antioxidants don't help. So the question is, maybe antioxidant therapy helps some patients but doesn't help others. One of the interesting aspects of this study that maybe the presence or absence of TRX-80 might determine whether antioxidant therapies will help. Furthermore, maybe TRX-80 levels might be able to guide patients as to whether or not they should take antioxidant therapy. There are many important aspects of this study that point toward future studies.
Dr. Mustapha Rouis: We thought about inhibiting the ADAM-10, ADAM-17 alpha secretase enzyme to prevent the cleavage process and I know that many drug companies are trying to find the specific inhibitors but the problem is these two enzyme are benefit in brain for enzymatic disease. So waiting to have a specific inhibitor for this enzyme that do not cross the hematoencephalic barrier to use it in humans but until that we may be the use or conceive the peptides it's better approach.
Dr. Carolyn Lam: I'm just loving this discussion because it's really bringing out a lot more to this paper than I realized as a clinician. Charlie could you end by just saying a few words about how we look at basic science papers in Circulation and the importance of the clinical translation element that we keep saying is our primary focus.
Dr. Charlie Lowenstein: Circulation is a great journal that covers important clinical topics. There's a lot of basic science that underlies some of these clinical topics so whenever we get a paper that gives us insight into a disease or reveals a new therapy and it's at the basic level we look very carefully at it. We want to know, will it help our readers understand something about the clinical process, clinical disease, diagnostics [inaudible 00:16:00] So when we get a paper we look at it very carefully and emphasize it has to be a basic paper that reveals a mechanism that's important to clinicians. That clinicians can understand and appreciate and gain insight about what's going on with their patients. I'm both a clinician and a scientist, I am charged with trying to figure out what basic concepts are relevant to our clinical audience.
Dr. Carolyn Lam: Thank you Mustapha, thank you Charlie and thank you listeners for tuning in this week. Don't forget to tune in again next week.
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. Our journal this week features an in-depth review on transcatheter therapy for mitral regurgitation, a very, very hot and interesting topic. You have to listen on, coming up right after these summaries.
Our first original paper this week sheds light on the influence of aging on aldosterone secretion and physiology. First author Dr. Nanba, corresponding author Dr. Rainey and colleagues from the University of Michigan in United States, examine the relationship between age and adrenal aldosterone synthase in 127 normal adrenals from deceased kidney donors. The donors' ages ranged from nine months to 68 years. The authors found that adrenals from older individuals displayed less normal aldosterone synthase expression and zona glomerulosa, and greater content of abnormal foci of aldosterone synthase expressing cells.
Furthermore, older age was independently associated with dysregulated and autonomous aldosterone physiology, in an ancillary clinical study of subjects without primary aldosteronism. This study therefore suggests that aging may be associated with a sub-clinical form of aldosterone excess and provides at least one potential explanation for age related cardiovascular risk.
The next study shows, for the first time, that the chemokine receptor, CXCR4, in vascular cells, limits atherosclerosis. The CXCL12 and CXCR4 chemokine ligand receptor axis is known to control cell homeostasis and trafficking. However, its specific in atheroprotection has thus far been unclear. This is addressed in today's study by first author Dr. During, corresponding author Dr. Weber, and colleagues of The Institute for Cardiovascular Prevention in Munich, Germany. In hyperlipidemic mice, the authors showed that cell-specific deletion of CXCR4 in arterial endothelial cells, or smooth muscle cells, marked the increase atherosclerotic lesion formation. Mechanistically, CXCR4 axis promoted endothelial barrier function through VE-cadherin expression and a stabilization of junctional VE-cadherin complexes. In arterial smooth muscle cells, CXCR4 sustained vascular reactivity responses, and a contractile smooth muscle cell phenotype. Whereas, CXCR4 deficiency favored the occurrence of macrophage-like smooth muscle cells in atherosclerotic plaques and impaired cholesterol efflux.
Finally, in humans, the authors identified a common allele variant within the CXCR4 locus that was associated with reduced CXCR4 expression in carotid RG plaques, and increased risk for coronary heart disease. Thus, the study suggests that enhancing the atheroprotective effect of arterial CXCR4 by selective modulators may open normal therapeutic options in atherosclerosis.
The next paper is the first to study the effects of rosuvastatin on carotid intima-media thickness in children, with heterozygous familial hypercholesterolemia. First author Dr. Braamskamp, corresponding author Dr. Hutten, and colleagues from Academic Medical Center Amsterdam in the Netherlands, study children with heterozygous familial hypercholesterolemia aged 6 to less than 18 years, with LDL cholesterol more than 4.9, or more than 4.1 millimoles per liter in combination with other risk factors, who received rosuvastatin for 2 years, starting at 5 milligrams once daily, with uptitration to 10 milligrams for children aged 6 to 10 years old, or 20 milligrams daily for those aged 10 to 18 years old.
Carotid intima-media thickness was assessed by ultrasonography at baseline, 12 months and 24 months in all patients and in age-matched, unaffected siblings. Carotid intima-media thickness was measured at 3 locations, the common carotid artery, the carotid ball, and the internal carotid artery in both the left and right carotid arteries. At baseline, the mean carotid intima-media thickness was significantly greater for the 197 children with heterozygous familial hypercholesterolemia compared with the 65 unaffected siblings. Rosuvastatin treatment for 2 years resulted in significantly less progression of increased carotid intima-media thickness in children with heterozygous familial hypercholesterolemia than in the untreated, or unaffected siblings. As a result, there was no difference in carotid intima-media thickness between the two groups after two years of rosuvastatin. These findings, therefore, support the value of early initiation of statin treatment for LDL cholesterol reduction in children with heterozygous familial hypercholesterolemia.
The final study highlights the therapeutic potential of a novel alpha calcitonin gene-related peptide for the treatment of heart failure. First author Dr. Aubdool, corresponding author Dr. Brain, and colleagues from King's College London in United Kingdom, tested the stable alpha analog of calcitonin gene-related peptide in 2 models ... First, an angiotensin 2 infused mouse, and secondly, pressure overload cardiac hypertrophy mouse model using suprarenal aortic ligation. They showed that systemic colon injection of the alpha analog blunted the angiotensin 2 induced rise in blood pressure, as well as the vascular and cardiac remodeling, changes in water consumption, and renal injury, that are normally associated with angiotensin 2 infusion. Furthermore, protective effects were also seen when starting the alpha analog treatment, only during the last week of the 2-week angiotensin 2 infusion, in other words, when hypertension was already established. Finally, the alpha analog preserved heart function, and diminished the degree of hypertrophy and fibrosis in the aortic ligation model.
Thus, these results demonstrate the therapeutic potential of the alpha calcitonin gene-related peptide pathway, and the possibility that this injectable alpha analog may be effective in cardiac disease.
Well, that wraps it up for this week's summaries! Now, for our featured discussion.
For our feature discussion this week, we're talking about trans-catheter therapy for mitral regurgitation, a very hot field and a field in which there have been a lot of advances. To help us break it down, and get right into the insights, the challenges, and potential solutions, I am so pleased to have the first author of this in-depth review paper, Dr. Paul Sorajja from Minneapolis Heart Institute Foundation and Abbott Northwestern Hospital, as well as Dr. Manos Brilakis, associate editor from UT Southwestern, here with us today!
Paul, could I start with you, and just ask you first to give us an idea of what we're talking about here when we talk about mitral regurgitation ... There are different kinds, which are we referring to, and what are the challenges involved in a trans-catheter therapy for mitral regurgitation?
Dr. Paul Sorajja: I think there are a number of challenges, I think the first thing is that MR is often thought of as one disease, but it's really an incredibly heterogeneous disease ... Broadly, we talk about primary versus secondary MR, but the mitral valve is so complex, with multiple different components, any one of which can disrupt and cause MR. When we're talking about trans-catheter therapy, it's often very easy, again, to think we could have one therapy that could treat a simply insufficient valve, but it's way more complex than that, and as a result, there have been many different approaches that have been developed, adding to the complexity of how we manage these patients.
Dr. Carolyn Lam: Right, and in your paper, I loved the way you grouped them, very logically, under those from mitral valve repair, and that for mitral valve replacement ... And then, under repair, you grouped it into leaflet versus targeting the LV ... Could you maybe give us some top-line insights on these techniques?
Dr. Paul Sorajja: Yeah, there are a number of different approaches that have mechanistically gone after the different components through the pathophysiology of MR, where there is leaflets, where there's analysts, cords, or ventricular approach ... I think it's somewhat simplistic to think of it that way, but as catheter-based technology, we are technically limited by what we can do from a catheter standpoint. I think it's inevitable to think about these catheter technologies as eventually being combined, rather than singular, in order to approach what surgeons do in the OR.
Dr. Carolyn Lam: Right, but then even going further, you spent quite a bit of the paper talking about trans-catheter mitral valve implantation ... So, replacing the mitral valve, that's really cool, could you tell us a bit about that, and about that important issue brought up about patient selection.
Dr. Paul Sorajja: Yes, it's a very good point, I think in terms of trans-catheter mitral replacement, I think that that's really where the future is going to go ... The simple analogy is that people think that it will follow the route of TAVR, but I think it will follow the route of TAVR more quickly so, because when you look at how the mitral valve is currently treated in the OR, sometimes, a lot of the times, patients can end up worse. Whereas, a trans-catheter solution actually, I think in terms of the safety margin, actually will equate a degree of safety relative to surgery, if it's done and developed correctly, as opposed to how TAVR's done. I think for TAVR, it's been a number of years for our field to be equivalent or superior to surgery, whereas I think with mitral, I think there's a lot of potential for mitral to have equated a degree of safety. As an example, in the Tendine Feasibility Study, it was published this past January ... A high-risk population, there was not a single procedure death, out of 30 patients ... And for these patients who would go to the OR with an eject fraction of 30 to 40 percent, I think that's quite remarkable.
Dr. Carolyn Lam: Wow, that's really exciting indeed! Manos, you handled this paper, and it's just so beautifully laid out ... That flow chart, I just want to refer all our listeners to the flow chart in Figure 7, that talks about maybe an approach that can be considered. Manos, could you share some thoughts on how this developed?
Dr. Manos Brilakis: Yeah, absolutely, and obviously Paul is the expert on this, but I think it's very important about this paper, and through discussions with Paul and through the development of the paper, is that there's more of a collaboration between the surgeons and the interventionists. So instead, if it's additional style of ... Or the interventionists are doing one thing and the surgeon is doing another, I think the key to success in the mitral field is working very closely together ... Many of those valves right now, the percutaneous valves, are done through a cut down and a typical approach, so working very closely to addressing the anatomic components of the mitral valve problem is a big plus.
The other thing I think that is very important is the new emergence of imaging, trying to understand whether the new mitral valve is going to create issues with LVOT obstruction or not. I think that's leading to a whole new understanding of when and how patients are even candidates for this approach, and I think Paul can elaborate more on this, but as things evolve, fewer and fewer patients are going to be excluded from these new technologies.
Dr. Carolyn Lam: Paul, would you like to take that? What do you think is happening and will happen with patient selection?
Dr. Paul Sorajja: There has been a challenge in current feasibility studies, in terms of getting patients in, the anatomical restraints are exactly what Dr. Brilakis has outlined. There's a certain bulkiness and size to the valve, which essentially poses risk for LVOT obstruction if the valve is too big ... As a feasibility study that's still early, or a field that's still early in its development, there's been a really conservative approach in terms of patient selection to ensure that LVOT obstruction doesn't happen. I think we're pushing the boundaries for that, and I think we've learned a lot from CT imaging, in terms of predicting LVOT obstruction, and I think the valves are also getting to be shorter in profile, which makes it less likely ... But that is definitely one of the limitations, and it's a limitation that exists, not just for trans-cat therapy but also for surgical therapy.
Dr. Carolyn Lam: Right, and then maybe a question for both of you ... What do you think the future is going to hold? What do we need to make this more mainstream, and where do you think this will leave surgical approaches? I know you said a combined approach, but maybe you could elaborate a little bit more?
Dr. Paul Sorajja: I do think, and I agree, I think Manos' point is spot on about that ... This will have to be multidisciplinary, the surgeons and cardiologists absolutely need to continue to work together, that's what's led to the successful development of TAVR, and I think that will be even more so for mitral, because the mitral valve is just infinitely more complex, and we have a lot to learn from the surgeons. But I think going forward, the collaboration is going to be a requirement, and then the training is also going to be a significant portion ... Putting in a mitral valve is much more complex than putting in an aortic valve ... I think if there's a safety margin that's demonstrated, I still think that it will be more appealing and more rapidly adopted than aortic disease.
Dr. Carolyn Lam: Well, Manos?
Dr. Manos Brilakis: No, I completely agree with Paul on that respect. I think, in my mind, at least, an again, this is from an early standpoint, the next big step would be to make it completely percutaneous, right now, you still have to do the cut down, and it's a little more invasive, although still safer than the completely open surgery, but maybe having a complete percutaneous system would be the next big step ... There's no question in my mind, as well ... And watching very closely how Paul and the surgical team are handling this, I think this is definitely the way for the future. Sometimes, in TAVR, it's not as technically demanding, and you don't really need to have too many people in the room, but for this procedure, it's definitely more important to have everyone in the room, and benefit from everyone's expertise.
Dr. Carolyn Lam: Manos, could I switch tracks for a moment now, and ask you to comment on the question that I get a lot ... You're an Interventionist, you handle a lot of the interventional papers for Circulation, and a lot of people are wondering, what makes papers like Paul's ... What makes interventional papers something that we would want to publish in Circulation? Could you share some thoughts?
Dr. Manos Brilakis: Absolutely, thanks Carolyn ... That's a big part, I think, of the appeal of Circulation right now. We're really trying to communicate to people that cutting-edge, clinical science is actually at the heart and the core of Circulation, and clinical content is what drives a lot of editorial ... Especially in intervention, where particularly interesting and new, cutting-edge technologies, new trials, observational studies ... But essentially, things that are cutting-edge, and are going to have a specific implication and impact in the way the field is going ... And this is part of Dr. Sorajja's paper, showing where the future lies in terms of trans-catheter mitral technologies, but along the same lines, we love to have cutting-edge papers on various aspects ... Coronary, peripheral, all aspects of interventional cardiologies, as well as interventional imaging ... The goal, again is to make the submission easy, there are not many honors requirements for submitting the papers, it's very simple to submit, and there's an answer going out very quick, so we're looking forward to receiving more and more interventional papers on cutting-edge science.
Dr. Carolyn Lam: Thank you so much for joining us today, and don't forget to tune in again next week.
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.
Now, the SGLT2 inhibitor, empagliflozin, has been shown to improve outcomes in the EMPA-REG OUTCOMES trial. But do these benefits also apply in the real world, and to other SGLT2 inhibitors as a class? Well, we may just have some answers this week in the CVD-REAL study. More soon right after these summaries.
The first original paper this week uncovers the mechanism of beneficial action of T-cells for proper healing after myocardial infarction. Now, the pro-inflammatory danger signal, adenosine triphosphate or ATP, is released from damaged cells, and degraded by the ectonucleotidase CD73 to the anti-inflammatory mediator, adenosine.
Using newly-generated CD4-CD73 null mice, first author, Dr. Borg, corresponding author, Dr. Schrader, and colleagues from Heinrich Heine University of Düsseldorf in Germany, showed that a lack of CD73 on T-cells enhanced tissue fibrosis and worsened myocardial function in the remodeling phase after myocardial infarction.
T-cells migrated into the injured heart and upregulated their enzymatic machinery to enhance the extracellular degradation of ATP to adenosine. T-cells lacking CD73 showed accelerated production of pro-inflammatory and profibrotic cytokines. Finally, the adenosine 2B receptor was upregulated on cardiac immune cells in the remodeling phase.
In summary, therefore, local adenosine formation by CD73 on T-cells appears to be the body's own defense mechanism to control inflammation induced by myocardial infarction. This is a mechanism that might be exploited to promote healing or remodeling by specifically targeting the adenosine 2B receptor in the infarcted heart.
The next paper provides insights on genetic determinants of susceptibility to peripheral artery disease, and specifically puts the spotlight on Bcl-2-associated athanogene-3, or Bag3, which is a cell chaperone protein previously identified in a genetic screen for determinants of tissue loss with hindlimb ischemia.
In the current study, Dr. McClung from East Carolina University, Brody School of Medicine in Greenville, North Carolina, and colleagues, used adeno-associated viruses to show that an isoleucine to methionine variant at position 81 in Bag3 was sufficient to confer susceptibility to ischemic tissue necrosis in BALB/c mice.
In a series of elegant experiments, they demonstrated that Bag3 was a modulator of ischemic muscle necrosis and blood flow. In summary, this study provides evidence that genetic variation in Bag3 plays an important role in the prevention of ischemic tissue necrosis, and highlights a pathway that preserves tissue survival and muscle function in the setting of ischemia.
The next study provides insights into inflammatory atherogenesis by studying psoriasis, a chronic inflammatory disease associated with an accelerated risk of myocardial infarction. First author, Dr. Lerman, corresponding author, Dr. Mehta from the NHLBI, National Institutes of Health in Bethesda, United States, and colleagues, hypothesized that the increased cardiovascular risk observed in psoriasis would be partially attributable to an elevated subclinical coronary artery disease burden composed of non-calcified plaques with high-risk features.
To test this hypothesis, they compared total coronary plaque burden, non-calcified coronary plaque burden, and high-risk plaque prevalence between 105 psoriasis patients, 100 older hypolipidemic patients eligible for statin therapy, and 25 non-psoriasis healthy volunteers. All patients underwent CT coronary angiography, and a sample of the first 50 psoriasis patients were scanned again at one year following therapy.
The authors found that patients with psoriasis had greater non-coronary burden and increased high-risk plaque prevalence compared to healthy volunteers. Furthermore, compared to older hypolipidemic patients, patients with psoriasis had elevated non-calcified burden, and equivalent high-risk plaque prevalence. Finally, improvement in skin disease severity was associated with an improvement in non-calcified coronary burden at one year.
The clinical implications are that patients with psoriasis have similar coronary artery disease risk as hyperlipidemic patients one decade older, and these patients with psoriasis should be screened earlier for cardiovascular disease and educated about their elevated risks. Further investigations focus on the longitudinal impact of psoriasis treatment on high-risk plaque morphology, as well as on the extent of cardiovascular risk mitigation in randomized trials.
Well, those were your summaries. Now for our feature discussion. Now, we've heard of the EMPA-REG OUTCOME trial, that prospective randomized, controlled trial, showing a substantial reduction in cardiovascular death and hospitalization for heart failure with the sodium-glucose cotransporter 2, or SGLT2 inhibitor, empagliflozin, and that's, remember, that was in patients with type 2 diabetes and established atherosclerotic cardiovascular disease.
Well, our paper today really extends our knowledge and tells us a bit more about the role of SGLT2 inhibitors in real-world clinical care. And I'm so please to have with us the first and corresponding author, Dr. Mikhail Kosiborod from Saint Luke's, Mid America Heart Institute, as well as Dr. Gabriel Steg, associate editor from Paris, France, joining us today. Hello, gentlemen.
Dr. Gabriel Steg: Hello.
Dr. Mikhail Kosiborod: Hi. Good morning, Carolyn.
Dr. Carolyn Lam: Mikhail, I am going to say what I said to you at the ACC and at the ESC Heart Failure: Congratulations on CVD-REAL. Please tell us about CVD-REAL.
Dr. Mikhail Kosiborod: Right, well, we know, as you just mentioned, that the EMPA-REG OUTCOME trial showed substantial reduction in cardiovascular death, and hospitalizations for heart failure in patients with type 2 diabetes and established cardiovascular disease. We were all very excited once that data got presented in September of 2015 in Stockholm, but there were several very important questions that weren't really addressed, and truly, could not be addressed, in EMPA-REG's trial.
The first, actually, and probably the most important is, we all know that clinical trials, while we regard them as the gold standard of evidence, as we should, they do have their own set of limitations, the most important of which is that they examine a relatively small sliver of patients; and many patients we see in the clinic, in the hospital, don't look like patients in clinical trials. I think the most important questions we tried to address was, "Will this translate to real-world clinical practice?"
The second was, as you recall, again, all patients on EMPA-REG had established cardiovascular disease, so we wanted to know whether the benefits associated with the use of SGLT2 inhibitors could potentially extend to lower-risk patients with type 2 diabetes without established cardiovascular disease, a much broader spectrum of patients.
And finally, and also very importantly, I think, the third question was, "Is it an empagliflozin-specific effect or is it a class effect?" These are all the critical questions we tried to address in the CVD-REAL study.
Dr. Carolyn Lam: Great. Could you give us the topline results, please?
Dr. Mikhail Kosiborod: Right. So, just as a reminder, we collected data from well-established registries in six countries, so the United States and some five countries in Europe, Sweden, Norway, and Denmark, and also, the United Kingdom and Germany. And really, the inclusion/exclusion criteria for the study were quite broad, you just had to have type 2 diabetes and be newly started on either an SGLT2 inhibitor or any other glucose-lowering medications, which was the comparative group.
And after we did the one-to-one propensity match to make sure, comparable samples, we ended up with about 154,000 patients, and each treatment group, over 300,000 patients overall. What we actually observed was a marked and highly significant reduction in the risk of hospitalization for heart failure that was associated with use of SGLT2 inhibitors versus other glucose-lowering drugs.
In fact, the magnitude of reduction in risk that was associated with SGLT2 inhibitors, so that outcome was quite similar, about 39% relative risk reduction, quite similar to what we see in the EMPA-REG OUTCOME trial. But this, of course, was for the entire class of SGLT2 inhibitors, so patients in the study were treated primarily with canagliflozin and dapagliflozin, with a small proportion being treated with empagliflozin.
We also saw dramatic and highly significant associated reduction in the risk of all-cause death with SGLT2 inhibitors versus other glucose-lowering drugs, about a 51% relative risk reduction, and the composite of those two outcomes, obviously, there was significant associated reduction in risk as well.
So, again, the hazard ratio estimate that we saw for these outcomes were quite similar, and in some cases, almost identical to what we've seen in EMPA-REG, but for a patient population that was much broader, in fact, about 90% of patients, close to 90% of patients in our study did not have established, documented cardiovascular disease. And, of course, as I mentioned before, important implications to these findings, in my opinion.
Dr. Carolyn Lam: Yeah, that is just remarkable. Gabriel, could you share some of the discussions that happened among the editors about this paper?
Dr. Gabriel Steg: We were really excited by this paper. I think this is truly a landmark paper for a number of reasons. It's a very large, multinational study, but even more than the size, I think what's interesting here are a couple of key aspects. First of all is data on all-cause mortality, which is a highly reliable outcome when you look at many of the observational studies.
Non-fatal outcomes can easily be skewed or biased in ascertainment or assessment, but this is relatively reliable. And here, we have a very large multinational cohort that finds benefits on death, heart failure, and their composite, which are remarkably consistent internally, consistent across countries, and consistent with the randomized trial data evidence from the EMPA-REG OUTCOME trial.
So that is striking, and this is consistent across six countries using a very large sample size. But again, the size of the sample is not the most important thing, because in observational studies, you often have very large sample sizes, but if you have bias in your observational study, the bias is just replicated times the size of the study.
The consistency here between the treatment effects across the various countries, the consistency with the efficacy assessed in randomized clinical trials is really a crux in the quality of the data and how believable the results are. Another key aspect that got us really excited is the fact that only a minute fraction of the data is related to use of empagliflozin.
Most of the data was acquired using other SGLT2, and we still only have results now with empagliflozin, we don't have outcome trial data with the other agents. They are pending, but pending the availability of these trials, the fact that this large study sees a consistent benefit, in terms of heart failure and mortality, of the other agents in the class suggests that this is a class effect.
And likewise, the fact that we're seeing these benefits in a population that is much, much broader than the population of EMPA-REG OUTCOMES is also very, very intriguing, and exciting, and makes us really want to see more data not only from the randomized trials that are upcoming, but also from this study.
Because now, what we would like to see is, see the detailed cardiovascular outcomes in these cohorts, and I know that Mikhail and his colleagues are working very, very actively on preparing these analyses. I think this is going to be exciting. This is the first of a series of landmark papers from a model observational study.
There are many issues with observational studies. This is almost as good as it can ever get, and I want to compliment Mikhail and the consortium that's with him, because this is a tremendous effort, across several countries, on achieving this. I think it's very exciting for our readership and for clinicians around the world.
Dr. Carolyn Lam: I couldn't agree more, and I share your compliments for Mikhail. Perhaps, Mikhail, could you give us a sneak peek at the future and the ongoing work?
Dr. Mikhail Kosiborod: We frequently think of, and I think perhaps mistakenly at times, think of clinical trials and observational real-world data as competing with one another. In many cases, they're really complementary, and I think if you really, kind of, think of interventions that we consider as those gold standards enshrined in clinical guidelines, or something we absolutely should be doing for our patients.
Just to pick one example, statins for secondary prevention after a cardiovascular event, for example, there is data from both sources suggesting that these drugs are highly beneficial, right? So it is very important to have data from both sides, and I think, as Gabriel mentioned, I look at CVD-REAL as a model, in many ways, of how compelling the data from non-randomized, large, real-world observational studies can be when done well.
In terms of a sneak peek for the future, there are many, many things going on. We are carefully examining the outcomes that we are reporting in circulation, including heart failure and all-cause mortality in various subgroups. We are, of course, as Gabriel mentioned, intently looking at other outcomes, including myocardial infarction, stroke, cardiovascular death, and a composite of major adverse cardiac events.
We're also examining some of the diabetes, one could argue, maybe, diabetes-specific outcomes, such as hypoglycemia rates. We, of course, as cardiologists tend to concentrate on cardiovascular outcomes, but it's also important to remember that there are other important outcomes that could be associated benefits.
So these medications may be associated with marked reduction of cardiovascular events, such as death and heart failure, but they may also reduce hypoglycemia rates and, of course, that's important from a quality-of-life standpoint for patients with diabetes, so some of that work is ongoing.
And I would say, importantly, one of the other things that we're hoping to be able to do in the future is to go beyond cardiovascular outcomes, and perhaps blood glucose-specific outcomes, such as hypoglycemia, and start looking at events such as renal disease events, which I think are very important, of course. Interact quite a bit with, I suspect, in many ways, with some of the cardiovascular benefits that we're observing with those agents, both in the clinical trials and, now, in large observational studies.
And that's just the beginning. I mean, I think it's fair to say that, as Gabriel mentioned, a huge amount of work went into putting this together, right? And we're actually not only expanding things from a standpoint of outcomes. We're also expanding things from a standpoint of countries that will be participating in CVD-REAL consortium.
So we're actually planning to add at least two or three more countries from Europe, Middle East, and Asia in the coming months, and more so in the future. And of course, once you have a resource like this, there are additional questions that can be addressed, actually, both with SGLT2 inhibitors as a class, but also with other classes of type 2 diabetes medication. So that's, I think, as much of a sneak peek as I can give you right now. Just definitely promise you that there is a lot more coming.
In addition to ADA, we're going to have abstracts being presented at ESC in August, and also the European Association for the Study of Diabetes meeting in Lisbon, in September, and there's going to be a lot more afterwards as well. So just stay tuned, I would say. This is definitely just the beginning. There's going to be a lot more coming.
Dr. Carolyn Lam: You took the words right out of my mouth. Listeners, stay tuned, and don't forget to tune in next week as well.
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 Youth National University of Singapore. Coming right up, we will be discussing fascinating new data on the prevalence of subclinical coronary artery disease in masters endurance athletes but first, here's your summary of this week's journal. The first paper provides insight into ischemic cellular post conditioning. Now, we know that cardiosphere derived cell therapy has been utilized as a strategy to treat ischemic heart disease and reduce chronic scar burden when administered months after myocardial infarction. In the current study, by first author Dr. de Couto, corresponding authors Dr. Marban and Berman from Cedars-Sinai Heart Institute in Los Angeles, California, the authors used rat and pig models of myocardial infarction to show that exosomes, which are nanosize lipid bi-layer vesicles, actually mediate the cardio protective effects of cardiosphere derived cells when administered after reperfusion of myocardial infarction.
They further show that treatment with either cardiosphere-derived cells or their secreted exosomes reduce infarct size and improved functional recovery. Using RNA sequencing to determine exosome content and alterations in gene expression profiles on macrophages from cardiac tissue or bone marrow, they found that a specific micro RNA species miR 181-B within the exosomes, acted on macrophages and was implicated as a key mediator of the cardio-protective benefits. Thus, this study gives new reason to test the idea that allogeneic cardiosphere-derived cells may be efficacious in preventing scar formation and improving cardiac function, when given in the earlier reperfusion period. The data further support that exosomal transfer of miR 181-B from these cardiospheric-derived cells into macrophages underlie the cardio-protective effects after reperfusion.
The next study describes a potential new therapeutic strategy for vasoproliferative retinopathy which can underlie age-related macular degeneration, the leading cause of blindness in industrialized nations. First author, Dr. Bucher, corresponding authors Dr. Yea and Friedlander, from the Scripps Research Institute in La Jolla, California used rodent models of retinal neo-vascular disease to show that Tspan-12, beta-catenin signaling plays an important role in the development of vasoproliferative retinopathy. As background, Tspan-12 belongs to the Tetraspanin family, which mainly includes cell surface proteins characterized by four transmembrane domains and two extra cellular domains.
Members of the Tspan family participate in a diverse cellular processes and act as signaling platforms by forming Tspan-enriched micro domains in plasma membranes. The authors went further to use a novel phage display combinatorial antibody library to specifically design a Tspan-12 blocking antibody which is capable of interacting with human and mouse Tspan-12 antigen. They then provided strong evidence that the Tspan-12 blocking antibody prevents developmental pathological neovascularization in murine models of vasoproliferative retinopathy. Combination therapy with a known anti-VEGF agent demonstrated significant synergy supporting the potential clinical use of the anti-Tspan-12 antibody as a novel angiomodulatory agent.
The next study addresses the paradox that blacks have higher coronary heart disease mortality compared with whites, but non-fatal coronary heart disease risks may be lower for black versus white men. To address this paradox, first author Dr. Colantonio, corresponding author, Dr. Safford and colleagues from Weill Cornell Medical College in New York, compared fatal and non-fatal coronary heart disease incidents and case fatality among blacks and whites in three studies. The Atherosclerosis Risk in Communities or ARIC study, cardiovascular health study, and reasons for geographic and racial differences in stroke or regards study, all stratified by gender.
They found that the incidents of non-fatal coronary heart disease was consistently lower among black versus white men, although black men have a higher burden of unfavorable social determinants of health and cardiovascular risk factors and a higher fatal coronary heart disease incidents. Following adjustment for social determinants of health and cardiovascular risk factors, black men and women had a similar risk of fatal coronary heart disease, but a lower risk of non-fatal coronary heart disease compared with white men and women respectively. Finally, blacks with incident coronary heart disease had a higher case fatality compared with whites and the difference remained similar after adjustment for social determinants of health and risk factors. Thus, there is an apparent lower risk for non-fatal coronary heart disease among black versus white men and women, which needs to be further studied. Blacks have a higher risk of their initial coronary heart disease event being fatal compared with whites, highlighting the need for reinforcing primary prevention in this population.
The next study provides important information on the burden of re-admissions after hospitalization for critical limb ischemia. First author, Dr. Kolte, corresponding Dr. Aronow and colleagues from Brown University in Providence, Rhode Island, used the 2013/2014 nationwide re-admissions databases to identify almost 61,0000 hospitalizations for primary diagnosis of critical limb ischemia during which patients underwent endovascular or surgical therapy. They found a 30-day re-admission rate of 20.4%. Independent predictors of 30-day re-admission included presentation with an ulcer or gangrene, age above 65 years, females, large hospital size teaching hospital status, known coronary artery disease, heart failure, chronic kidney disease, anemia, coagulopathy, obesity, major bleeding, acute myocardial infarction, vascular complications, and sepsis. Interestingly, mode of revascularization was not independently associated with re-admissions.
The most common reasons for re-admissions included infections, persistent or recurrent manifestations of peripheral artery disease, cardiac conditions, procedural complications, and endocrine issues. Finally, the costs of 30-day re-admissions for critical limb ischemia during the study period were 624 million U.S. dollars. Thus, this study provide knowledge of independent predictors and reasons for re-admissions that will help clinicians and hospitals to identify, develop, and implement strategies to reduce re-hospitalizations and healthcare costs associated with critical limb ischemia.
The final study tells us that there may be a direct relationship between life-long exercise volume, and coronary atherosclerosis in athletes. Dr. Aengevaeren and colleagues from Radboud University Medical Center in the Netherlands, studied 284 middle-aged men engaged in competitive or recreational leisure supports, using contrast enhanced CT to assess coronary artery calcification and plaque characteristics.
Participants also reported life-long exercise history patterns and exercise volumes were quantified as metabolic equivalent of task or met minutes per week. They found that participants in the more than 2,000 met minutes per week group had a higher prevalence of coronary artery calcification and atherosclerotic plaques. The most active group did, however, have a more benign composition of plaques with fewer mixed plaques and more often, only calcified plaques. These observations may explain the increased longevity typical of endurance athletes, despite the presence of more coronary atherosclerotic plaques in the most active participants. Well, that wraps it up for your summaries. Now for our featured discussion.
Our current physical activity guidelines recommend 150 minutes of moderate exercise and that's supposed to protect against cardiovascular disease and increase longevity. However, what do we really know about the dose response relationships and the effects of exercises doses that exceed current recommendations. Well, recent data, including a paper in this week's issue, suggests that long-term, high volume endurance exercise may actually accelerate, rather than reduce coronary atherosclerosis. To discuss this exciting paper, we have the corresponding author, Dr. Sanjay Sharma, from Saint George's University of London, as well as editor of digital strategies and associate editor at UT Southwestern who handled this paper, Dr. Amit Khera. Welcome, gentleman.
Dr. Amit Khera: Good morning.
Dr. Sanjay Sharma: Thanks for having us.
Dr. Carolyn Lam: First, Sanjay, oh yikes! As a runner and as a person who strongly advocates regular exercise, please, please, put us out of our misery. Tell us what you've found and what you think are the possible explanations.
Dr. Sanjay Sharma: I'm a runner too, and I don't think anyone would argue that the benefits of exercise on the cardiovascular system are unrivaled. People who exercise regularly do reduce their risk of an adverse event from a heart attack by 50% when they're in their 5th and 6th decade and they live around three years longer than people who don't exercise at all. Now as you rightly point out, the current recommendation suggests 2 1/2 hours of moderate physical activity per week and by that I would mean, at maximum, a 15-minute mile pace. Clearly, our endurance athletes exercise much, much more than that. They exercise 10 to 20 times greater than that volume and in parallel with this has been the emergence of a large number of people participating in marathon runs. For example, in Europe, there were two million marathon runs per annum and that figure's going up by about 5%.
Coinciding with this burgeoning increase in endurance exercise, is the development of several reports that show that exercise may cause release of biomarkers of cardiac damage. Animal experiments have shown that exercise may cause scaring in the heart and human studies have shown that some marathon runners have more calcium in their coronary arteries compared to relatively sedentary individuals. One of the problems with these studies is firstly, the biomarker release is very transient, it goes away after about two days. Animal experiments cannot really reflect what goes on in human beings because they're artificial and animals are forced to exercise with electrical shocks, et cetera. The studies in human beings have been conducted in runners who have been former smokers.
In fact, the most commonly reported study or cited study, contained individuals of whom 50% had risk factors for coronary artery disease. What we decided to do was to do a clean study, where we took 150 individuals who had none of the risk factors for coronary artery disease and 92 relatively sedentary controls who exercise within the normal limits. We have to exclude a lot of people because we have to exclude anyone that had ever smoked, anyone that had high blood pressure, high cholesterol, or a family history of permanent cardiac disease. We actually subjected them to all sorts of investigations and we found that a small number of male runners had more calcium in their arteries compared to sedentary individuals.
Dr. Carolyn Lam: Wow! Please tell us that there's something good that you can say about that. First of all, I really want to congratulate you on this most elegant study and Amit, I'm sure you put in what the editor's thought but we're just so proud to be publishing such a high quality study here. Amit, is there anything you might want to add of what the editors thought?
Dr. Amit Khera: Sure, I first want to congratulate Dr. Sharma and his colleagues. This was a carefully done study and we've talked a bit about the coronary calcium but there was extensive investigation and I really think this advanced the field. Sounds like all three of us are runners, so this hit home to all of us and as he mentioned, this has been a very hot area and one that's been very controversial. I think here what we have is a manuscript that really helped move the field forward, helped us better understand the biology. The one thing I'll comment on that we found very interesting was the observation that those that were the masters athletes actually had more of a calcific phenotype, where as those that were not looked like a soft plaque phenotype, if you will. Actually, if you look, we have a companion article in circulation looking at sort of dose dependent finding a similar finding. My question, now turned back to Dr. Sharma is, what do you counsel your patients now with these findings? Has it changed now how you recommend exercise or your thoughts on how you counsel them?
Dr. Sanjay Sharma: Well, we examined 152 different athletes, or masters athletes in 92 controls. These athletes were aged 56 years old, who'd been training for 36 years and had immediate marathon number of 13. Now, what we've found in these individuals is that a small number of males, that's 11%, had a coronary artery calcium score of more than 300. Some men had more plaques than sedentary individuals and these plaques were distributed throughout all three coronary arteries. When we looked at the pathology of the plaques very carefully, we found that the plaques in the athletes were calcified. Indeed, 72% of athletes had very calcified plaques. We know that such calcified plaques are stable, they're less likely to fissure and are less likely to cause coronary thrombosis and therefore, acute myocardial infarction.
This led us to propose that although exercise may be causing some atherosclerosis through the sheering and stressful source during exercise of the bending and kicking of vessels, we believe that the repair mechanism here is different to that seen in people who smoke or who have high cholesterol or high blood pressure. The repair mechanism results in very calcified and stable plaques in athletes and this may actually mitigate the risk of acute myocardial infarction and may explain why the number of people who actually suffer an acute myocardial infarction during a marathon run is very small, around 1 in 50,000, and no different to the number of people who suffer a sudden cardiac arrest playing football or basketball, due to congenital or inherited abnormalities of the heart.
Dr. Carolyn Lam: Sanjay, those are just such important points to keep in mind as we read your paper. It did strike me as a significant minority, actually, of these long term endurance athletes who develop significant coronary artery calcification and it could potentially be a clinically benign phenotype. At the end of the day, this is a cross-sectional study, isn't it? We can't, I suppose, extrapolate into the clinical events. What are your postulations there and what could be future work that you're planning?
Dr. Sanjay Sharma: Well, you make a good point. This is a cross-sectional study and the demonstration of an increased cardiopathy calcium does not necessarily reflect future cardiac events. We have followed these individuals up for the last 18 months. These masters athletes and have not demonstrated a single one to develop an acute event that would last 18 months. We really don't know what the meaning of these plaques is. I think the only thing to do now, being we've got the liberty of having so many people that do marathon runs and so many people who've been exercising for three or four decades, we can actually do a prolonged follow up study, so the answers will be a while coming. To follow these people up with high calcium, just to see whether they do go on to develop adverse events in the future. All our study has shown is that some male athletes who've exercised lifelong get an increasing number of plaques. These plaques appear to be calcified and stable and the long term effects of such plaques is unknown.
Dr. Carolyn Lam: Sanjay, just circling back to Amit's question earlier and maybe Amit, you could take it to after this. What do we recommend to our athletes who come in and have a high coronary artery calcium score? Do we tell them to stop?
Dr. Sanjay Sharma: I certainly wouldn't and I'm much less worried about an increase coronary calcium score in a lifelong runner or cyclist than I was 10 years ago. It appears that these plaques are there in some individuals, they are calcified, they appear stable. Given the fact that we know that coronary events during marathon running in experienced runners are very, very low indeed. I don't think I would be keen to do anything about it, not even consider stacking therapy based on our findings at present. As I said before, we do need longitudinal follow up to really identify all ascertain the precise implications of these plaques in masters athletes.
Dr. Carolyn Lam: Right, and this is again recognizing that your particular population was free of traditional cardiovascular disease. Of course, if we were to find these risk factors in our athletes, we would most certainly treat the traditional risk factors. Amit, anything to add there?
Dr. Amit Khera: I think that was an excellent point about his approach to counseling patients. I will mention on the editorial staff, we felt like this was such an interesting area with emerging data and fast moving, that it was warranting of an editorial. I recommend people to look at the one by Aaron Baggish and Ben Levine. I think they had a very similar conclusion and that was that they don't necessarily proscribe exercise in patients with high coronary calcium but rather, focus on risk mitigation strategy, focusing on risk factors as we normally would do. I think the conclusions are similar and the thoughts in that editorial were insightful, pairing both of these papers and helping us make sense out of this really evolving field.
Dr. Carolyn Lam: Well, thank you Sanjay and Amit for this wonderful discussion. I learned so much as I'm sure our listeners did. You've been listening to Circulation On The Run. Tune in next week.
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. What is the association between fetal congenital heart defects and maternal risk of hypertensive disorders of pregnancy? We will be discussing new data in this area in just a moment, following these summaries.
The first paper describes the effect of long-term metformin and lifestyle measures on coronary artery calcium. This is a paper from Dr. Goldberg of George Washington University Biostatistics Center and colleagues of the Diabetes Prevention Program Research Group. The Diabetes Prevention Program and its outcome study is a long-term intervention study in subjects with prediabetes, which showed reduced diabetes risk with lifestyle and metformin compared to placebo.
In the current study, the authors looked at subclinical atherosclerosis, which was assessed in 2,029 participants using coronary artery calcium measurements after 14 years of average follow-up. They found that men but not women with prediabetes treated with metformin for an average duration of 14 years had lower coronary calcium scores than their placebo counterparts. No difference in coronary calcium scores was observed in the group receiving a lifestyle intervention as compared to the placebo group.
These findings provide the first evidence that metformin may protect against coronary atherosclerosis in men with prediabetes, although demonstration that metformin reduces cardiovascular disease events in these subjects is still needed before firm therapeutic implications of these findings can be made. The reason for an absence of an effect in women is unclear and deserves further study.
The next study provides insights on the physiology of angina from invasive catheter laboratory measurements during exercise. Dr. Asrress of Royal North Shore Hospital in Sydney, Australia, and colleagues, studied 40 patients with exertional angina and coronary artery disease who underwent cardiac catheterization via radial axis and performed incremental exercise using a supine cycle ergometer. As they developed limiting angina, sublingual GTN was administered to half the patients and all patients continued to exercise for two minutes at the same workload. Throughout exercise, distal coronary pressure and flow velocity, and central aortic pressure were recorded using sensor wires.
Using this novel invasive approach, the authors showed that administration of GTN ameliorated angina by reducing myocardial oxygen demand as well as increasing supply with a key component being the reversal of exercise-induced coronary lesion vasoconstriction. This was evidenced by the fact that there was a relationship between the diastolic velocity pressure gradient with significant increase in relative stenosis severity. In keeping with exercise-induced vasoconstriction of stenosed epicardial segments and dilation of normal segments, with trends towards reversal with GTN.
Thus, this study describes the development of a paradigm where patients with coronary artery disease can exercise while simultaneously having coronary and central aortic hemodynamics measured invasively, and has shown that this provides a unique opportunity to study mechanisms underlying the physiology of angina. In treating patients with exercise-induced angina, the results highlight the importance of after-load reduction and the use of agents that reduce arterial wave reflection and promote coronary artery vasodilation.
The next study provides mechanistic insights into reverse cholesterol transport, where excess cholesterol is removed from macrophage-derived foam cells in atherosclerotic plaques. It suggests that melanocortin receptor-1, or MC1-R, may play a role. As background, the melanocortin system, consisting of melanocyte-stimulating hormones and their receptors, regulate a variety of physiological functions, ranging from skin pigmentation to centrally-mediated energy balance control. At the cellular level, the biological actions are mediated by G protein-coupled melanocortin receptors, such as MC1-R. MC1-R not only affects melanogenesis in the skin but also has immunomodulatory effects through its wide expression in the cells of the immune system.
In the current study from Dr. Rinne of University of Turku in Finland, and colleagues, human and mouse atherosclerotic samples and primary mouse macrophages were used to study the regulatory functions of MC1-R. The impact of pharmacological MC1-R activation on atherosclerosis was further assessed in apolipoprotein E deficient mice. Their findings identified a novel role for MC1-R in macrophage cholesterol transport. Activation of MC1-R conferred protection against macrophage foam cell formation through a dual mechanism. It prevented cholesterol uptake while it concomitantly promoted reverse cholesterol transport by increasing the expression of ATP-binding cassette transporters, ABCA1 and ABCG1.
Thus, the identification of MC1-R in lesional macrophages, demonstration of its role in regulating reverse cholesterol transport, combined with its established anti-inflammatory effects, suggests that MC1-R could be a novel new therapeutic target for preventing atherosclerosis.
The next study suggests that obesity-related heart failure with preserved ejection fraction, or HFpEF, is a genuine form of cardiac failure and a clinically relevant phenotype that may require specific treatments. First author, Dr. Obokata, corresponding author, Dr. Borlaug, and colleagues from Mayo Clinic Rochester and Minnesota studied 99 patients with obese HFpEF with a BMI above 35, with 96 non-obese HFpEF with a BMI less than 30, and 71 non-obese controls without heart failure. All subjects underwent detailed clinical assessment, echocardiography, and invasive hemodynamic exercise testing.
The authors found that, compared to non-obese HFpEF, obese HFpEF patients displayed greater volume overload, more biventricular remodeling, greater right ventricular dysfunction, worse exercise capacity, more impaired pulmonary vasodilation, and more profound hemodynamic arrangements, despite a lower NT-proBNP level. Obese HFpEF patients displayed other important contributors to high left ventricular filling pressures, including greater dependence on plasma volume expansion, increased pericardial restraint, and enhanced ventricular interaction, which was exaggerated as pulmonary pressure load increased.
These data provide compelling evidence that patients with the obese HFpEF phenotype have real heart failure and display several pathophysiological mechanisms that differ from non-obese patients with HFpEF. These and other issues are discussed in an accompanying editorial by Dr. Dalane Kitzman and myself. We hope you enjoy it.
The final study identifies a novel long noncoding RNA that regulates angiogenesis. As background, although we know that the mammalian genome is pervasively transcribed, a large proportion of the transcripts do not encode a protein, and are thus regarded as noncoding RNAs. Based on their length, they can be divided into small or long noncoding RNAs, long being described as more than 200 nucleotides. Although their function is not fully understood, long noncoding RNAs have been increasingly reported to mediate the expression of other genes, affect the organization of the nucleus, and modify other RNAs.
In the current study by first author, Dr. Leisegang, corresponding author, Dr. Brandes, and colleagues of Goethe University in Frankfurt, Germany, epigenetically controlled long noncoding RNAs in human umbilical vein endothelial cells were searched by axon array analysis following knockdown of the histone demethylase JARID1B. The authors discovered a novel noncoding RNA named MANTIS to be strongly upregulated. MANTIS is located in the antisense strand of an intronic region of the gene for annexin A4, calcium- and phospholipid-binding protein. MANTIS is a nuclear long noncoding RNA that is enriched in endothelial cells but also expressed in other cell types. Reducing MANTIS levels led to impaired endothelial sprouting, tube formation, attenuated endothelial migration, and inhibition of the alignment of endothelial cells in response to shear stress.
Brahma-like gene 1, or BRG-1, was identified as a direct interaction partner of MANTIS, implying a role of MANTIS in the formation of the switch/sucrose non-fermentable chromatin remodeling complex. MANTIS binding to BRG-1 was shown to stabilize the BRG-1 interaction, hence by inducing an open chromatin conformation, MANTIS was proposed to maintain the endothelial angiogenic potential. The implications of these findings are discussed in an accompanying editorial by Dr. Zampetaki and Mayr from Kings College London.
That brings us to the end of our summaries. Now for our feature discussion.
Today, we are going to be discussing the association between fetal congenital heart defects and maternal risk of hypertensive disorders of pregnancy. To discuss this, I have the first and corresponding author of our feature paper, Dr. Heather Boyd, from Statens Serum Institut in Copenhagen, and our familiar Dr. Sharon Reimold, content editor for special populations from UT Southwestern. Welcome, Heather and Sharon.
Dr. Heather Boyd: Thank you.
Dr. Sharon Reimold: Thank you.
Dr. Carolyn Lam: Heather, it's a topic that I can't say I'm very familiar with, association between fetal congenital heart defects and maternal risk of hypertensive disorders of pregnancy. Could you start by sharing why would we think there would be a link? What was the hypothesis you were testing?
Dr. Heather Boyd: A couple years ago, there was a paper published in the European Heart Journal that reported evidence of angiogenic imbalance in women with fetuses with major congenital heart defects, so women who were pregnant with babies that had heart defects, and then in fetuses that were terminated because of this kind of defect. My research group focuses a lot of attention on preeclampsia. In the last decade or so, angiogenic imbalance in preeclampsia has been a really hot topic. Women with preeclampsia, particularly women with early-onset preeclampsia, have big angiogenic imbalances. When we saw the European Heart Journal paper, we immediately thought, "What's the connection between preeclampsia and heart defects in the offspring?"
Dr. Carolyn Lam: Oh!
Dr. Heather Boyd: Exactly. That was our entry point to it, was the term "angiogenic imbalance" in that paper sort of was a flag for us. It wasn't a completely new idea, but we in Denmark have one big advantage when considering research questions that involve either rare exposures and/or rare outcomes, and that's our National Health Registry. We have the ability to assemble these huge cohorts and study conditions like heart defects with good power, so we decided just to go for it.
Dr. Carolyn Lam: That makes a lot of sense now. Please, tell us what you did and what you found.
Dr. Heather Boyd: The first thing we did was look at the association between carrying a baby with a heart defect and then whether the mom had preeclampsia later in the same pregnancy. We had information on almost 2 million pregnancies for this part of the study. We found that women carrying a baby with a heart defect were seven times as likely as women with structurally normal babies to develop early preterm preeclampsia. We defined that as preeclampsia where the baby has to be delivered before 34 weeks, so the really severe form of preeclampsia. Then, women carrying a baby with a heart defect were almost three times as likely to develop late preterm preeclampsia as well. That's where they managed to carry it until 34 weeks but it has to be delivered some time before 37 weeks.
These findings were similar to those of other studies, but we were able to go a step further and look at individual heart defect subtypes. What we found there waws that these strong associations were similar across defect categories. Then we decided to see if we could shed any light on the origin of the problem, whether it was coming from the mom's side or the baby's side. To do this, we looked at women with at least two pregnancies in our study period to see whether preeclampsia in one pregnancy had any bearing on the chance of having a baby with a heart defect in another pregnancy or vice versa.
This part of the study included 700,000 women. We found very similar findings. We found that women with early preterm preeclampsia in one pregnancy had eight times the risk of having a baby with a heart defect in a subsequent pregnancy. Late-term preeclampsia in one pregnancy was associated with almost three times the risk of offspring heart defects in later pregnancies. Then, we found that it worked the other way around too. Women who had a baby with a heart defect were twice as likely to have preterm preeclampsia in subsequent pregnancies.
Those results were really, really exciting, because whatever mechanisms underlie the associations between preterm preeclampsia in moms and heart defects in the babies, they operate across pregnancies. Therefore, that pointed towards something maternal in origin.
Dr. Carolyn Lam: That is so fascinating. Sharon, please, share some of the thoughts, your own as well as those of the editors when we saw this paper.
Dr. Sharon Reimold: I think that there's a growing data about the links between hypertensive disorders of pregnancy and preeclampsia with subsequent abnormal maternal outcome. But this paper, I think, has implications for how we look at moms who are going to have offspring with congenital heart defects as well as those with preeclampsia. For instance, I would look at a patient now that has preeclampsia, especially in more than one pregnancy, to identify that they may be at risk to have offspring with congenital defects in the future if they have additional children. But the mom is also at risk based on other data for developing other cardiovascular risk factors and disease as she gets older. It was really the link going back and forth with the hypertensive disorders and the congenital defects that we found the most interesting.
Dr. Carolyn Lam: That struck me too, especially when you can look at multiple pregnancies and outcomes. That's amazing. You know what, Heather, could you share a little bit about what it's like working with these huge Danish databases? I think there must be a lot more than meets the eye.
Dr. Heather Boyd: It's an interesting question, because I'm a Canadian and I was trained in the US. I did my PhD in epidemiology at Emery, and then I moved to Copenhagen. When I first got here, I was absolutely floored at the possibility of doing studies with millions of women in them. It opens some amazing possibilities, like I said earlier, for certain outcomes and certain exposures. You just need to have a question where the information you want is registered.
Dr. Carolyn Lam: Yeah. But I think what I also want to put across is, having worked with big databases, and certainly not as big as that one, it's actually a lot of work. People might think, "Oh, it's just all sitting there." But, for example, how long did it take you to come to these observations and conclusions?
Dr. Heather Boyd: I have a fabulous statistician. I think she's the second author there, Saima Basit. She spends a lot of her time pulling together data from different registers. But yes, you're right. The data don't always just mesh nicely. The statisticians we have working with us are real pros at this sort of data slinging.
Dr. Carolyn Lam: Could I just pose one last question to both of you. What do you think are the remaining gaps?
Dr. Sharon Reimold: I think that this is a clinical link. Then, going back to figure more about what's going on biologically to set up this difference? Because right now there's really no intervention that's going to make a difference, it's just a risk going forward. This is sort of like medicine done backwards, that there's this association and now we need to figure out exactly why.
Dr. Heather Boyd: I can piggyback on what Sharon said a little bit, because I think one of the things we need to remember is that not all women with preeclampsia have babies with heart defects. Not by a long shot. What we need to do now is to figure out what distinguishes the women who do get this double whammy from the vast majority who don't.
One of the things that Denmark does really nicely is that there are large bio banks. One of the things we want to do is go back to bank first trimester maternal blood samples and see if we can identify biomarkers that are unique to the women with both preterm preeclampsia and babies with heart defects. That's one of the things we're thinking about to address this gap. Because, as Sharon says, we've got to figure out what the mechanism is.
The other thing we want to do is to see whether the association between preeclampsia and heart defects extends, for example, to other things, to cardiac functional deficits, for example, because it's probably not just severe structural defects. If there's an association, it's probably on a continuum. Are babies born to preeclamptic moms, do their cardiac outputs differ? Do their electrical parameters differ? Do they just have different hearts?
We're really lucky because right now the Copenhagen Baby Heart Study is offering to scan the hearts of all infants born at one of the three major university hospitals in the Copenhagen area. We're about to have echocardiography data on 30,000 newborn hearts to help us look at this. I'm really excited about that possibility.
Dr. Carolyn Lam: I've learnt so much from this conversation. I'm sure the listeners will agree with me. Thank you both very, very much.
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, and I'm just so thrilled to be joined by a co-host today and that's Dr. Amit Khera. He's the Editor of Digital Strategies for Circulation from UT Southwestern. Welcome, Amit.
Dr. Amit Khera: Hi, Carolyn. Thank you for letting me participate today and we're excited about this Fit featured podcast.
Dr. Carolyn Lam: We have a very special episode today. First of all, because we don't have a print issue that follows this week and so, there's no usual summaries, but we do have special guests and these are the Fellows-in-Training.
Now, we sent out a call online to all the fellows to tell us a bit about themselves as well as which articles in Circulation stood out to them, and we had an overwhelming response from all over the world, of which these two fellows really stood out.
So, join me in welcoming Dr. Punag Divanji from United States and Dr. Mayooran Namasivayam from Australia. Welcome.
Dr. Punag Divanji: Hi, thank you so much for having us.
Dr. Mayooran Namasivayam: Thank you very much.
Dr. Carolyn Lam: So, Punag, could you start us off by telling us a little bit about yourself, your training, your dreams, and why you chose that particular paper from this month's Circulation that spoke to you?
Dr. Punag Divanji: I'm currently a second year Cardiology Fellow, completing my General Fellowship and beginning a research year at the University of California in San Francisco. I will be pursuing research in women's health and subsequently pursuing an Interventional Cardiology Fellowship. Subsequently, this, hopefully, will lead to a career in academic Interventional Cardiology.
Dr. Carolyn Lam: Now, we asked you to pick an article from Circulation. I really wonder which was your pick?
Dr. Punag Divanji: I think one of the most important ones that spoke to me recently was the CVD-REAL Study, the comparative effectiveness of cardiovascular outcomes in new users of SGLT2 inhibitors. The CVD-REAL Study from Dr. Kosiborod of the Saint Luke's Mid America Heart Institute and an international group of colleagues was the first multinational retrospective observational study to compare CVD outcomes in patients with type 2 diabetes, who were prescribed sodium-glucose co-transporter 2 inhibitors or SGLT2 inhibitors. The primary objective of this study was to compare the risk of hospitalization for heart failure in patients with established type 2 diabetes that were newly initiated on SGLT2 inhibitors.
Patients who were newly initiated on an SGLT2 inhibitor had a 39% lower risk of hospitalization for heart failure compared with those newly initiated on other glucose lowering drugs. There was significant geographic variation in the use of SGLT2 inhibitors, with the predominance of canagliflozin in the United States, dapagliflozin in European countries, and no more than 7% penetration of empagliflozin in any of these six countries.
Despite this, there was no signs of significant heterogeneity across the countries, suggesting the cardiovascular benefits observed may be class related. In addition, the reduced risk of hospitalization for heart failure was stable across sensitivity analyses, including sequential occlusion of other glucose-lowering drugs like insulin, metformin, or even the GLP-1 receptor agonists, the only other class of drug with benefits in CVOTs.
Dr. Carolyn Lam: Punag, give us an idea why this paper stand out to you. I mean, we had the EMPA-REG Outcome Trial, and I'd love to know how much you use this medication in your practice, and did it change after this?
Dr. Punag Divanji: This is, I think, a profoundly important study for a number of reasons. Type 2 diabetes carries a significant burden of cardiovascular risk. It's associated with complications like heart failure, myocardial infarction, and all caused death, of course. We have for many years been treating cardiovascular disease in diabetes with an aim towards reduction in hemoglobin A1c. However, we know that reduction in hemoglobin A1c has not necessarily resulted in improvement in cardiovascular outcomes. The EMPA-REG Outcome Study and the recent CANVAS Study seem to suggest that these medications may have a benefit, these SGLT2 inhibitors may have a benefit in cardiovascular outcomes.
In practicing clinical cardiology, we often refer our patients with diabetes to endocrinologists or to their Primary Care physicians to initiate diabetes medications, and aren't directly involved in that decision making. The result of trials like these though, seems to indicate that medications that can have a cardiovascular outcome in this high-risk patient population, may indeed benefit from the input of cardiologists.
With the high penetrance of medications like insulin and metformin in this population, there may indeed be room for initiation of SGLT2 inhibitors, and if it is indeed a class effect, as this seems to indicate, there is considerable room for addition of this medication into our [inaudible 00:05:13]. And potentially a pretty significant benefit, in terms of cardiovascular outcomes.
Dr. Carolyn Lam: I agree. I took that with me as well, especially because, you know, it's as the name says, CVD-REAL was supposed to be a real world setting, and it included diabetic patients, like you nicely emphasized that didn't have established cardiovascular disease, so maybe addressing a wider population than that was seen in EMPA-REG Outcomes. Thank you so much, Punag.
Could I turn to you now, Mayooran? So, all the way from Australia, could you tell us a little bit about yourself and your training?
Dr. Mayooran Namasivayam: I'm in my third year of Cardiology Fellowship at St. Vincent's Hospital in Sydney, Australia. I'm also involved with post-graduate research doing my PhD through the University of New South Wales and the Victor Chang Cardiac Research Institute doing clinical work here at St. Vincent's. And my particular areas of interest are cardiac imaging and heart failure, and I'll be looking to do an advance Fellowship in imaging and/or heart failure in the near future.
Dr. Carolyn Lam: Brilliant! So, which paper did you pick over the last month? Which spoke to you?
Dr. Mayooran Namasivayam: I picked two papers. But the first one I was going to discuss was the paper by Nickenig and colleagues, which looked at trans-catheter treatment of severe tricuspid regurgitation using edge-to-edge MitraClip technique, which I found very interesting. So this was an observational feasibility study, which primarily looked at safety outcomes at 30 days, but also the technical feasibility of performing this procedure for tricuspid regurgitation therapy. Essentially the authors demonstrated that there was a reduction in tricuspid regurgitation severity or TR grade in 91% of their cohort. There are also improvement in soft surrogate endpoints such as New York Heart Association class and six-minute walk test distance, and importantly there were no intraprocedural major adverse events; however, there were three in-hospital deaths.
I found the study particularly interesting because it's a very emerging technology using the MitraClip in the tricuspid position and to date, this is the largest study on this subject. It recruited patients from 10 centers. I think, interestingly, the 22 patients in that cohort, had both mitral and tricuspid valve disease treated with the MitraClip technique. I think it really bodes well for the future of transcatheter valve interventions and I think shows that this is A, technically possible, but in the early stages at least safe and possibly efficacious, but certainly we would need longer term data to confirm that this is making a difference for people and that it is safer in the long term. I think it raised a lot of important issues going forward using transcatheter interventions in the tricuspid position.
Dr. Carolyn Lam: You said that you're interested in heart failure and training in heart failure. Do you see that a lot, because I certainly do?
Dr. Mayooran Namasivayam: Yes, we see it quite a lot at our center. Our center is a [inaudible 00:08:10] transplant center and so a lot of our patients with cardiomyopathy have quite bad tricuspid regurgitation. Many of them in the setting of left heart failure, some in the setting of pulmonary hypertension, and then some in our post transplant population we see some tricuspid regurgitation as well.
I think we're following on from the surgical literature, which shows that if you have some degree of mitral regurgitation that requires surgical intervention and there's at least moderate tricuspid regurgitation, then correction of that may be of some benefit. If we follow that on using transcatheter methodology, then certainly this may be an option going forward for patients that have transcatheter mitral valve repairs or replacements. One of the benefits of using a transcatheter method is you're not limited to the one opportunity you have with cardiopulmonary bypass where a decision's made to seek either both mitral and tricuspid together or potentially do it as staged procedure if we were to use the transcatheter approach.
So, yeah, we certainly see severe tricuspid regurgitation a lot and I think options such as this really do give us therapeutic opportunities for our patients who may not have the surgical robustness to have a general anesthetic and a big tricuspid valve replacement or repair surgically. I think the other key population where this may be relevant is tricuspid valve intervention in the post transplant setting where re-operation in the setting of immunosuppression may be problematic and fraught with adverse events. I think it's quite promising going forward and I'd love to see more data on this in the near future.
Dr. Carolyn Lam: Indeed, and it's just so nice to hear about how the articles in our journal have, well, if I may say, inspired both of you.
Amit, I know that we want to get our fellows talking a little bit more about Circulation On The Run. Can I hand it over to you now?
Dr. Amit Khera: Sure, absolutely, and thank you Carolyn for handing the baton.
I first want to give my full disclosure. I'm a Fellowship Program Director and of all the hats I wear, I find that to be one of the most important ones. You know, at Circulation, we certainly appreciate that Fellows-in-Training are the future of cardiovascular medicine and cardiovascular science. We are actively looking for ways to better engage the Fellows-in-Training and to make sure we're meeting their needs and enhancing their career trajectory. So, I appreciate both of you being on the call today and for this inaugural Fit podcast series, and this will not be the last of this series. So, we look forward to doing more.
Maybe I will ask each of you individually, and I'll start with you Mayooran, can you tell me a little bit about how you consume the medical literature. I appreciate that it's generational and back in the day, everybody would get their print copy in the mail and now there's many different ways to consume it. Tell me a little bit about how you go through the medical literature and your way around that.
Dr. Mayooran Namasivayam: I tend to do a regular periodic browsing of the online journals. I tend to have a few journals, one of which is Circulation that I read sort of on a weekly or at most, fortnightly basis. Just to dig out the key articles of interest and the major updates. At our hospital the fellows have a weekly journal club meeting, which I actually chair. It's quite refreshing to get everyone's different opinions in their own areas of interest from the fellows to discuss topics of interest from various journals.
So, for me personally, it's a combination of browsing online journals with combining a more formal setting as our journal club. But from a research perspective, I use things like the RSS feeds and Journal Alerts, so journal articles that come up in key topics of research interest for myself. With regards to clinical practice, I tend to browse. Speaking to colleagues of mine, they use various things like social media or apps which will highlight major developments or summarize key articles. I think increasingly, that will be the way forward. But that's the way I go about it.
Dr. Amit Khera: What I really like what you said were a few things. Obviously there's an overwhelming amount of literature and by using tools like RSS feeds and table of contents, you can sort of keep up. I like that you're complementing that at your institution with this deep dive of journal club; this thing that many institutions including ours do, where you're really vetting articles in detail and hearing different perspectives. So, a nice blend of ways to consume it.
Punag, I'm going to ask you a little bit about social media. When I looked, turns out CVD REAL, the one that you chose, had an altmetric score of 487, so we think of impact factor, but altmetric's a whole other way to look at impact of our articles.
I'm curious about your thoughts on social media and the place of social media with disseminating scientific literature. I know many fellows are actively involved on Facebook and Twitter and other pathways. Tell us a little bit about your thoughts on that.
Dr. Punag Divanji: You know, very similar to the practice described in Australia, it's very similar to what we do here. We have weekly journal clubs, we discuss these articles with the faculty and really try to integrate it into our practice. A big part of that at, I think, many institutions across the country is the use of social media.
It is particularly robust, I think, in the cardiovascular field, especially at national or international meetings wherein late breaking clinical data is rapidly disseminated. The outcomes and a few important trials that will impact clinical practice are rapidly disseminated, such that we are able to, I think, quite quickly access information, but beyond that, learn for example, the description is such that medical literature is doubling every two to three years. It's difficult to keep pace with that, but when thought leaders in the field present data that they find most interesting, most useful, or most relevant to patient care on a platform like social media, it's, I think, a wonderful way for Fellows-in-Training to quickly aggregate high quality data. It's something that I rely on heavily.
Dr. Amit Khera: I think that's a great point, and where things have changed now is not only can you get information quickly through social media, but as you pointed out, the ability to interact with luminaries in the field to get their opinion on it and even engage in a conversation. That certainly wasn't available several years back and I think it's a great advance for Fellows-in-Training.
I'm going to stick with you for a second and hear your thoughts a little bit on how Circulation may better engage Fellows-in-Training or meet their needs.
How can Circulation or other journals for that matter help in the pathway for Fellows-in-Training?
Dr. Punag Divanji: I think the concerns of Fellows-in-Training are unique in comparison to those already in practice. We are at a point in our careers where we're trying to learn the basic important groundwork of cardiology, but at the same time, given the rapid evolution of data, it's imperative that we have the ability to learn new things on top of that foundation.
Engaging fellows in that way, I think, involves a strategy that looks at a couple of different things. One is obviously social media, which is, let's be honest one of the core ways that trainees interact, and let's be honest, one of the most common things you see a trainee doing is looking at their phone.
Dr. Amit Khera: And faculty.
Dr. Punag Divanji: And faculty for that matter, fair enough. But if you're able to provide information via Twitter or via this Circulation app and be able to alert someone of a new update in the field or a new guideline document or a way to better risk stratify patients that come in with myocardial infarction, this type of rapidly accessible data I think plays well to the [ethos 00:15:32] of the fellow wherein we like to be able to do things quickly and effectively, but also expand our knowledge in the most efficient way possible.
Dr. Amit Khera: That's very insightful. So, if I hear you correctly, it's sort of continuing to make sure that we disseminate information quickly and rapidly to Fellows-in-Training in a way that is easy for them to consume.
This brings to the point about when we look at our metrics, the podcast and other digital media strategies we have really hit broadly in an international audience, which we're very excited about.
Certainly, Mayooran, I'm going to ask you as well your views on how can Circulation or other journals for that matter help engage Fellows-in-Training or enhance their training and career trajectories?
Dr. Mayooran Namasivayam: I guess today is a wonderful opportunity for fellows to participate in Circulation's online activities and engage with fellows from around the world, so this is one such example. I think echoing some of the thoughts of Dr. Divanji, as a fellow, you're doing many things and you're wearing many hats. You're learning new procedures, you're learning core cardiology, you're involved in research, you're doing on-call activities and clinical duties, and sort of amassing the latest evidence and putting that together and working out how that's going to change your practice now and in the future is important, but is not always easy to do.
I think features such as Circulation's podcast, which summarize key developments sort of state-of-the-art review articles, guideline summaries, which come out in Circulation, and even the simple things like the summaries that come out on the print journals which say what is new and what are the clinical implications, which allow us to read that in a minute or two, and then read on if we're so interested, but at least get a summary or a snapshot of a major article. I think those features are really key in sort of summarizing key developments in a short and accessible way. I think as been discussed already, engaging with the newer media, social media, online media in the way that other publishing modalities such as newspapers are sort of engaging with their audience I think, is certainly important in the future to an increasingly time-poor audience.
Dr. Amit Khera: Well, glad to hear that these features are resonating well with you both and it's certainly helping you in terms of accessing and understanding the relevance of these articles in your daily practice.
The final question, I'll finish with you and then come back to Punag, is, as Carolyn says every week, this is your backstage pass to the editorial process, so a way to look behind the curtain or Oz if you will on how journals work and we certainly strive for transparency at Circulation.
So, I'm going to maybe ask you if you have any questions for us on how the journal works or any questions regarding the editorial process?
Dr. Mayooran Namasivayam: I guess one of the things that I was wondering was you must, particularly at Circulation, just be inundated with a huge array of papers, which I'm sure all are of excellent quality.
When you're looking at a paper quickly to make a decision about whether it's something you'd pursue further or look into, what gives you that instinct that you know this is probably a good paper? Is it the abstract? Is it the cover letter? Is it the title? What gives you that first impression that we should really look into this a bit further?
Dr. Amit Khera: Well that's a fantastic question. I'll answer and I'll see if Carolyn wants to add anything as an associate editor as well.
First you have to realize that yes, there's enormous volume of papers, but the most important thing is to assemble an expert team. I think Dr. Hill, our editor-in-chief, Joe Hill has certainly done that. He's established an international group of associate editors that are well-accomplished across the breadth of cardiovascular spectrum, so your interest is in heart failure, you have a couple of imaging type articles, Punag has talked about women's cardiovascular health and also diabetes and cardiovascular disease. We have editors that really have expertise on each of these areas.
The first level is our editorial, editor-in-chief, and deputy editors, et cetera who'll take the first pass at which articles seem to be well done and would meet priority for Circulation. Then distribute them to editors that are content experts, that really understand those areas well. I take that responsibility very seriously when I get a paper. I know I've been on the other end of that. It's a tremendous amount of work. All the authors have contributed, patients have contributed their data. So, we take that responsibility incredibly seriously.
We try to be thoughtful, that if it's a paper that really will not meet priority, we should turn it around quickly and let the authors know that so that they can then move onto another journal and not waste time. The flip is, if something seems that in our field, in our expertise would meet priority to our readers and could advance the field, we send it out for expert review, then have a very thoughtful discussion, even in advance online, through a web portal and then as a group with all of our editors across the world, to really think critically about each paper, it's merits and ways to strengthen it. We always try to do that, which is to not only say yes or no on a paper, but what can we tell an author to make a paper better, because we want the very best products coming out on Circulation.
I hope that gives you an idea of how we think about it. It's sort of a tiered approach, starting with our editor-in-chief and deputy editors and then down to associate editors. Again, we try to turn it around, how would we want our papers treated if we were submitting to a journal?
Carolyn, do you have anything to add to that.
Dr. Carolyn Lam: Yeah.
So, Mayooran, that's great question. I think I can guess where it's coming from, sort of if one were to submit a paper to Circulation, is there any particular part that you would want to focus on, because that's the part that immediately catches our attention, right? I think that's what you're asking.
Well, I would say without a doubt it's the science. So, you talked about the cover letter, you talked about abstract and things, the most important bar that the paper has to cross is validity. Then, right next to that would be novelty. So, for us, you know, once we can see that the science is well done and the results look robust, that has to be there before anything even happens beyond. Then, that's when the process kicks in like Amit said. Then we look at it from our specialty points of view and make sure that it's something novel and something that would be of interest to our Circulation audience.
Does that answer your question?
Dr. Mayooran Namasivayam: It does. It does, thank you both very much. Thank you.
Dr. Amit Khera: All right, I'm going to now pitch the same question to you, Punag.
What are your thoughts? What sort of questions you have for us behind the curtain of Oz and the editorial process?
Dr. Punag Divanji: You know it's quite interesting, one of the most compelling components of the Circulation on the Run podcast is at the end when Dr. Lam has a wonderful discussion with the associate editor that was responsible for the article and the authors and gives us an idea not only of what drove their process of scientific discovery, but also what drove the editors to really believe in that article to warrant publication; to say that this is something that our readers need to see. I think that really quite remarkable to gain that point of view.
My question is, you seemed to strike this balance between basic translation and clinical research when publishing each week. There are often a variety of topics that come from all three fields. Each week in the publication, there seems to be this balance between basic translational and clinical research wherein the readers really are able to gain perspective into the entire field of cardiology from articles that range from clinical outcomes from blood sugar management to the [pathophysiology 00:22:57] of takotsubo syndrome.
How do you, as editors, strike that balance in each issue? How do you decide which articles are going to be published in concert with others?
Dr. Amit Khera: That's a great question. Sort of looking at the spectrum of types of articles and types of science and how do you decide sort of what goes together. Kind of like a meal, you know, what components go together.
Dr. Carolyn Lam: I'd like to call it wine paring.
Dr. Amit Khera: Wine pairing. I like that. So, if it's a roast, what sort of red wine and so forth. I think that's an excellent question.
I think first, we do strive for balance and that, as you know, Dr. Hill has a ... his lab is a basic science lab, and Circulation has always been a journal which does the hightest quality science including both basic science and clinical and translational research. I also say we have other offerings as you know, which are thought pieces on my mind, and perspective pieces. So we really try to have the full spectrum. As we talk about, there are many people that enjoy their vegetables, the hard core original research articles, but a lot of people also like the deserts and the appetizers, these other types of articles that I mentioned.
I think it's trying to find that right balance. We always like to have a balance of all of those together, because we appreciate there's a spectrum of readers and at the same time, we also appreciate that I'm more of a clinical researcher, I can gain insight and value from reading basic science research and similarly the basic scientist could gain value from the types of clinical articles we try to place in Circulation.
So I think maybe as was mentioned, a little bit of a menu and a wine pairing we include this whole spectrum of different types of offerings, but I think the one bar is they all have to be articles that have some clinical implications, be it clinical, translational, or basic science, even the epidemiologic studies research that I do, they all have to, in the end, have some sort of clinical importance or relevance. I think that's the benchmark for all of the articles.
Carolyn, do you want to add anything?
Dr. Carolyn Lam: No, I think you got it all. In fact, Amit, I'm going to turn it back to you for the last question.
As Editor of Digital Strategies for Circulation, tell us, what's in store?
Dr. Amit Khera: Well, you know, it's been a great first year and I think many would say one of the highlights has been the podcast for sure. I think we've developed a platform of social media engagement, of learning how to work though our digital strategies platforms and setting a high bar for our podcast.
Now it's time to go to level two, or next level. How do we enhance what we're offering? How do we get creative about new types of podcasts, like this one we're doing today? How do we think about more interactive social media engagement? How do we further enhance the way we distribute science across the world? So, we have a big appetite and big ambition, but I think that is what we should be doing when we have such good science and making sure we disseminate it broadly.
So, I think you'll see building on the platform we've already established, and apropos to today, I hope we really bring the Fits along with us on this ride to further expand our offering of our science.
Dr. Carolyn Lam: Thank you so much for joining us on this special episode. Don't forget to tune in next week.
Dr. Carolyn Lam: Welcome to Circulation on the Run your weekly podcast summary and backstage pass to the journal and it's editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
Is it time to end our debates on short versus long duration of dual anti-platelet therapy? Well I will be discussing this with two very special guests in just a moment. But first here is your summary of this week's journal.
The first paper tells us that HDL particle number may serve as a biomarker of residual risk when assessed on statin therapy. First author Dr. Khera, corresponding author Dr. Mora from Brigham and Women's Hospital and colleagues of the JUPITER trial assessed HDL cholesterol levels, apolipoprotein A-1, cholesterol efflux capacity and HDL particle number at baseline and 12 month in a nested case control study of the JUPITER trial. That was a randomized primary prevention trial that compared rosuvastatin to placebo in individuals with normal LDL but increased CRP levels.
In the current study the authors found that cholesterol efflux capacity was moderately correlated with HDL cholesterol, apoA-I, and HDL particle number. Baseline HDL particle number was inversely associated with incident cardiovascular disease, while there was no significant association for baseline cholesterol efflux capacity, HDL or apoA-I levels. On-statin cholesterol efflux capacity was inversely associated with incident cardiovascular disease but HDL particle number again emerged as the strongest predictor.
Thus for both baseline and on-statin analyses, HDL particle number was the strongest of four HDL-related biomarkers as an inverse predictor of incident events and biomarker of residual risk. Whether therapies designed to enhance cholesterol efflux capacity or an increased HDL particle number can also reduce cardiovascular risk however remains uncertain.
The next study sheds light on mechanisms underlying the de-differentiation and lineage conversion of adult human fibroblast into functional endothelial cells. First author Dr. Zhang, corresponding authors Dr. Rehman and Malik from University of Illinois College of Medicine first generated CD34+ progenitors by de-differentiating adult human skin fibroblasts and showed that these intermediate progenitors could give rise to endothelial cells as well as erythrocytes. They then showed that lineage conversion of fibroblasts via partial de-differentiation recapitulated in part the embryonic development of the vasculature as evidenced by up regulation of anti-aging enzyme telomerase and the bi-lineage potential of the generated progenitors.
Importantly they showed that transcription factor SOX17 functioned as a switch which regulated the cell fate of CD34+ progenitors towards an endothelial versus erythroid lineage. Finally implanted fibroblast derived CD34+ progenitors stably engrafted to form functional human blood cells in mice that improved cardiac function after myocardial infarction. Thus the molecular switch SOX17 provides a means to optimize the generation of endothelial cells for vascular tissue regeneration or disease modeling.
What do drones have to do with out of hospital cardiac arrest? Well in this next study by first author Dr. Boutilier corresponding author Dr. Chan and colleagues from University of Toronto, the authors hypothesized that a drone network designed with the aid of a mathematical model combining both optimization and queuing could reduce the time to AED arrival.
Using data from over 50,000 historical out of hospital cardiac arrests covering over 26,000 square kilometers in Ontario, Canada, they found that a drone network designed to reduce the median AED arrival time by three minutes relative to the historical 911 response could also reduce the 90th percentile of the AED arrival time by between 6 minutes and 43 seconds in most urban regions and 10 minutes and 34 seconds in most rural regions.
Thus this study tells us that drone delivered AEDs have the potential to be a transformative innovation in the provision of emergency care to cardiac arrest patients especially those who arrest in a private or rural setting.
The next study provides thresholds for ambulatory blood pressure among African Americans. Dr. Ravenall and colleagues from New York University School of Medicine analyzed data from the Jackson Heart Study, a population-based cohort comprised exclusively of African-American adults and of whom more than 1000 participants completed ambulatory blood pressure monitoring at baseline.
Based on the outcome derived approach for systolic blood pressure and a regression derived approach for diastolic blood pressure, the following definitions corresponded to clinic blood pressure of 140/90 and were proposed as ambulatory blood pressure definitions for African Americans. Daytime blood pressure above 140/85, 24 hour blood pressure above 135/80 and nighttime blood pressure above 130/75 mmHg. Note that these ambulatory blood pressure thresholds identified for African Americans were higher than those from published recommendations mainly derived in European, Asian and South American populations. The use of these ambulatory blood pressure thresholds for African Americans will lead to a lower prevalence of daytime, 24 hour and nighttime hypertension compared with the current published recommendations.
The next paper provides pre-clinical evidence of a novel target in plaque information in atherosclerosis. Dr. Stachon and colleagues from Heart Center Friburg University in Germany hypothesized a functional role of the signal axis ATP binding to purinogenic receptor P2X7 in inflammasone activation and chronic inflammation driving atherosclerosis.
In an elegant series of experiments they showed that P2X7 receptor activation was crucial for inflammasone assembly and interleukin-1-beta secretion. The lack of P2X7 in mice abolished inflammasone activation in atherosclerotic lesions. P2X7 was expressed in murine and human atherosclerotic lesions. LDL receptor deficient mice lacking P2X7 receptor had reduced plaque inflammation and were less prone to develop atherosclerosis.
Thus this study shows that P2X7 inhibition could be a treatment strategy against plaque inflammation in atherosclerosis.
The next paper describes the first prospective clinical study of adenosine use in pediatric and young adult patients after heart transplantation. Now prior to this study adenosine was relatively contraindicated post-transplant due to a presumed risk of prolonged atrioventricular block in denervated hearts.
In the current study first author Dr. Flyer corresponding author Dr. Silver and colleagues from Columbia University performed a single center prospective clinical study testing whether adenosine caused prolonged asystole after transplant and if it was effective in blocking AV nodal conduction in healthy heart transplant recipients aged 6 months to 25 years presenting for routine cardiac catheterization. Following catheterization, a transvenous pacing catheter was placed and adenosine was given following a dose escalation protocol until AV block was achieved.
Eighty patients completed adenosine testing. And no patient required rescue ventricular pacing. AV block was observed in 77 patients with the median longest AV block of 1.9 seconds and the mean duration of adenosine effect of 4.3 seconds.
Thus, this study suggests that adenosine may be safe and effective in patients post transplantation and establishes both a safe and effective starting dose of 25mcg/kg or 1.5mg for patients weighing 60kg and more. It also establishes a stepwise therapy escalation plan to avoid prolonged bradycardia. Although patients after heart transplantation may require less adenosine to achieve AV block it appears to be safe and effective as therapy for evaluation and or treatment of tachycardia in this population.
Well those were your summaries, now for our feature discussion.
Today for our feature discussion we are talking about a very familiar situation, dual anti-platelet therapy following coronary intervention and the decision of long versus short duration of therapy. A debate we've heard many times but according to the perspective piece in today's journal, maybe a debate we should end. And I am so pleased to have the author, Dr. Glenn Levine from Baylor College of Medicine as well Dr. Laura Mauri associate editor from Brigham and Women's Hospital.
Dr. Laura Mauri: Thank you Carolyn.
Dr. Glenn Levine: Thank you.
Dr. Carolyn Lam: Glenn would you like to start by presenting your case. It's time to end a dualistic short versus long duration of DAPT debate. I really like that title, tell us more.
Dr. Glenn Levine: Thank you Carolyn.
The point we make in our editorial is that over the last five or six years there have been studies comparing what I term standard, which is usually about 12 months DAPT versus shorter duration DAPT and there are other studies comparing standard DAPT versus longer duration DAPT. Those generated important information in different people interpret them in different ways. What though has happened over the last several years is certainly for both educational and entertainment value at meetings as well in editorials, the idea of how long people should be treated with DAPT has been oversimplified to whether all patients should be treated with short duration or long duration. And Laura herself knows that as she has been in many of these debates.
While I think that initially that was educational and entertaining, I think these days people understand those points and a greater issue is in that we should treat some people with short duration, some with what I call standard and some with long duration. And rather than debating whether everyone should treated with short or everyone should be treated with long, I think what we need to focus on now is which patients should be treated with short duration, which are probably best treated with a standard duration and which are best treated with prolonged or extended duration DAPT.
And that in a nutshell is the main point that we make in this perspective editorial.
Dr. Carolyn Lam: Laura, so do you agree?
Dr. Laura Mauri: I couldn't agree more. I think clinicians really are looking for guidance and what happens at these debates is you see these polarizing opinions that debaters are asked to defend when in actuality there's such a wide spectrum of what individual patients need. And the real question I think going forward is how to end these debates and how to provide really more tailored information so clinicians and patients can make better decisions together. And I think that's really where the piece that Glenn has written really helps direct us.
Dr. Carolyn Lam: Yeah, Glenn, I mean are we talking about the usual risk versus benefits and precision metsan or individualized risk assessment here?
Dr. Glenn Levine: Yeah, what we're talking about is looking at the ischemic risks which are primarily leg stent thrombosis or spontaneous MI versus the bleeding risks which is obviously bleeding and balancing them. And there clearly are decision tools available to clinicians. Laura has pioneered the DAPT score which is an incredibly user friendly and easy tool to use to assess which patients should be continued with prolonged DAPT or not. And there are also some other tools out there including the Paris registry score perhaps a little more complex and then there's also now the precise DAPT score which one can at least assess bleeding risk and indirectly assess the ischemic and bleeding risk.
But really I think that is the focus now on balancing bleeding and ischemic risks and having pools to allow clinicians to easily do that.
Dr. Carolyn Lam: That's true. Now do you think guidelines have to catch up or have they caught up?
Dr. Glenn Levine: Our DAPT duration guideline was coming out just as Laura's DAPT score was about to be published, several months after it had been presented. And we did mention the DAPT score in our paper, it was too early to formally incorporate it into the guidelines. Nevertheless, the way our guidelines are written, they clearly give practitioners the option for individualizing therapy based on ischemic and bleeding risk and Laura's DAPT score fits perfectly into what we aim to do, namely to encourage practitioners to assess patients on an individual level and assess what duration of DAPT is best.
Dr. Carolyn Lam: I do have a question for Laura here though. I see Asian patients, I'm talking to you here from Singapore. And sometimes you wonder the trial situations and what you derive there. How does it differ from real world and how is it impacting your practice for example Laura?
Dr. Laura Mauri: That's a great question. I think you have a number of points there. One is the generalized ability or results from one trial across the world where you might have many different patient populations. And while the DAPT score was an international trial it would be interesting to see more data coming out from other different countries. And as you know there are trials in Asia that have looked at randomized DAPT duration as well.
I think now that we have better access to information especially in cardiology globally, we can get that information and better tailor therapy. When we look at any one randomized trial the results might seem kind of black and white and to certain extent so do guideline recommendations but we are getting better at using the results from randomized trials to really identify risk factors. I think that with time we'll be able to either validate the DAPT score in other patient populations or develop tailored scores from unique data sets. I think the challenge really is making sure that we still get good randomized evidence for our treatment decisions but then when we have treatments that have both benefit and risk that we identify which sub-populations of patients really do achieve most of the benefit. And then the other populations that might be harmed. And that's really what we try to do with this score.
And I think what you'll see, you asked about precision medicine which usually we think about using genetics but I think there's so much just really basic information that we have about patient lesion characteristics and other specific factors that we record routinely in their medical records that we can use and you'll see this, I think more and more frequently across different areas of investigation and in cardiovascular medicine.
One really interesting example recently was this French trial. Data was used to be able to predict, very similar to what we did, but to predict which patients would benefit from lower blood pressure without the risk of more aggressive treatment.
Dr. Carolyn Lam: Yeah, I love the way you put that. Those are really words of wisdom, I do think that that is the way cardiovascular medicine is gonna move. Glenn, how do you put all this into practice for yourself?
Dr. Glenn Levine: I think whether or not I formally calculate a DAPT score or Paris registry score, I think clearly we integrate the factors in those scores into our everyday practice. And clearly there are patients who are at high bleeding and low ischemic risk and vice versa. I would also encourage listeners to in addition to all the scores, one has to think about the consequences of a recurrent MI or stent thrombosis. Obviously someone who has stent thrombosis of a proximal LED lesion, if they already have a depressed EF or occluded RCA, those consequences are likely much more dire then someone who occludes say at a distal OM3 stent who has the normal ejection fraction. It also encourages them to think about the consequences of stent thrombosis as well as the consequences of a recurring MI.
Dr. Laura Mauri: Just to make it clear, we know that clinicians have always tried to balance these different risks of ischemia and bleeding when faced with this decisions. I think the challenge really has been the limited amount of information that we've had to be able to do that. And so we've really just used kind of our gut until recently when we've had several large randomized data sets to be able to look to. And what that's done is it's given us the ability to construct these new tools to be able to make practice more data driven. Now still individualized but based on data that's tailored to our patients.
And so I think we can use that to be able to improve outcomes. That being said, we don't want to rely on a statistic or a score alone and things like the DAPT score are based on patients like the ones that were enrolled into the randomized trial. Those were patients who could take longer anti-platelet therapy. It helps to identify who can take it for longer. But there are patients who get anti-coagulation or have other serious bleeding risks who really are going to benefit from new technologies to be able to shorten anti-platelet therapy.
Dr. Carolyn Lam: Well thank you Glenn once again for a wonderful perspective piece that has really got us thinking about situations even beyond dual anti-platelet therapy. Thank you Laura for your insights and thank you listeners for joining us today. Join us again next week.
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.
In our feature discussion today, we will be talking about insights from the PROMISE Trial regarding the prognostic value of non-invasive cardiovascular testing in patients with stable chest pain. First, here's your summary of this week's journal.
The first paper reports novel findings on gene smoking interactions in coronary heart disease. Co-corresponding authors Dr. Salahin from the University of Pennsylvania and Dr. Riley from Columbia University and colleagues used data on almost 61,000 coronary heart disease cases and more than 80,000 controls to investigate effect modification by smoking behavior at established coronary heart disease and smoking-related genetic loci.
They found that the cardio-protective effects associated with allelic variation at the A-D-A-M-T-S seven, or ADAMTS7 locus, were attenuated by 60% in patients who smoked tobacco, compared to those who did not smoke. Allelic variation in ADAMTS7 associated with reduced coronary heart disease risk, was associated with reduced ADAMTS7 expression in human aortic endothelial cells and lymphoblastoid cell lines.
Furthermore, exposure of human coronary artery smooth muscle cells to cigarette smoke extract led to induction of ADAMTS7. These human genomic data therefore provide new insights into potential mechanisms of coronary heart disease in cigarette smokers and suggests that inhibition of ADAMTS7 may be a novel potential therapeutic strategy for coronary heart disease that may have particular benefits in individuals who smoke cigarettes. This is discussed in an editorial entitled Holy Smokes, an Interaction, by Dr. Braxton Mitchell.
The next paper provides first evidence that genetic over-expression of CD39 may offer ischemic cerebral protection. CD39 is an ectoenzyme with a PYRase activity, which cleaves ATP and ADP. CD39 is expressed on the surface of myeloid and vascular endothelial cells where it dissipates the high local concentrations of ATP and ADP, which would otherwise serve as potent pro-inflammatory and pro-thrombotic signals.
In the current study from first author Dr. Bick, corresponding author Dr. Pinsky from University of Michigan Medical Center and colleagues, authors used a model of permanent middle cerebral artery occlusion to show that CD39 expression reduced edema, infarct volume, and inflammation with corresponding improvements in neurological outcomes, compared to control mice. Over-expression of CD39 in only the myeloid cells also reduced cerebral infarct volume. Thus, amplification of endogenous CD39 expression, or even administration of exogenous circulating CD39, may be of future interest as a therapeutic target to minimize ischemic injury caused by cerebral ischemia.
The next paper provides pre-clinical data to show that MicroRNA93 may have a therapeutic role in peripheral artery disease. First author Dr. Ganta, corresponding author Dr. Annicks and colleagues from University of Virginia, used MicroRNA-106b-93-25 cluster knockout mice and showed that MicroRNA93 over-expression alone was sufficient to enhance angiogenesis, arteriogenesis, and perfusion in ischemic muscle via increased M2-like macrophages.
MicroRNA93 targeted interferon regulatory factor 9 to inhibit immune response gene 1, and itaconic acid generation in macrophages to induce M2-like macrophage polarization. Furthermore, MicroRNA93 over-expression produced a paracrine effect on macrophages that induced angiogenesis and skeletal muscle recovery under hypoxic conditions in vitro.
Thus, these data demonstrate that MicroRNA93 induces beneficial effects in multiple cells that can enhance perfusion in ischemic limb and thus identifies MicroRNA93 as a putative therapeutic target in clinical peripheral artery disease.
The next study is a large scale genetic analysis that represents the most comprehensive causal assessment of adiposity with cardiometabolic diseases to date. Co-corresponding authors Dr. Cassis and Dale from University College London used 97 snips for BMI, and 49 snips for waist-hip ratio adjusted for BMI, to conduct mendelian randomization analysis in 14 prospective studies supplemented with coronary heart disease data from CADRIoGRAM+C4D, stroke data from METASTROKE, Type II Diabetes data from DIAGRAM and lipids data from GLGC Consortium.
They found that both waist-hip ratio adjusted for BMI, and BMI had causal effects on coronary heart disease and Type II Diabetes, and were associated with higher left ventricular hypertrophy, glycemic traits, interleukin 6 and circulating lipids. However, only waist-hip ratio adjusted for BMI increased the risk of ischemic stroke. Thus, both the amount of adiposity and its distribution play important roles in influencing multiple cardiometabolic traits and the development of cardiometabolic disease.
Furthermore, the findings indicate that body fat distribution has multiple roles in disease that are independent of general adiposity. This suggests that physicians should pay attention to measures of adiposity beyond BMI.
The next study addresses the conundrum that clinical trials show benefit of lowering systolic blood pressure in people aged 80 years and above, but yet, non-randomized epidemiologic studies suggest lower systolic blood pressure is associated with higher mortality. In the current study by Dr. Ravindrarajah and colleagues of King's College London, a population based cohort study was conducted using electronic health records of 144,403 participants aged 80 years and older, registered with family practices in the United Kingdom, and followed for five years.
Mortality rates increased with frailty level, and were highest at a systolic blood pressure of less than 110 millimeters mercury. Furthermore, systolic blood pressure trajectories showed an accelerated decline in the last two years of life, without evidence of intensification of anti-hypertensive therapy.
Thus, a terminal decline of systolic blood pressure in the final two years of life suggests that non-randomized epidemiological associations of systolic blood pressure with higher mortality may be accounted for by reverse causation. That is, participants with lower blood pressure values were closer on average to the end of life. This is discussed in an accompanying editorial by Dr. Naveed Sattar.
Well, that wraps it up for our summaries. Now for our feature discussion.
The evaluation of stable patients presenting with suspected coronary artery disease is by far one of the most common diagnostic evaluation strategies that we need to undertake in cardiovascular medicine. There's a whole host of evidence supporting prognostication based on various non-invasive tests, such as anatomic imaging with coronary computed tomography angiography, but also with stress testing, or functional testing, such as stress nuclear or echocardiography, or exercise electrocardiography.
However, our paper today really sheds light on the comparison of these two strategies. And I'm just delighted to have starts with me. First, the primary author of the paper, from the PROMISE Trial, Dr. Udo Hoffmann, from Massachusetts General Hospital, Harvard Medical School, and the editorialist of a beautiful accompanying editorial, Dr. Leslee Shaw from Emory University School of Medicine, Atlanta, Georgia.
Dr. Udo Hoffmann: Hi, Carolyn. Hi, Leslee.
Dr. Leslee Shaw: Hi, Udo, how are you?
Dr. Carolyn Lam: So, Udo, could you start by just sharing what you did in this PROMISE Trial?
Dr. Udo Hoffmann: The Promise Trial is a large comparative effectiveness trial that was done between 2009 and 2012, with follow-up ending 2013, at [inaudible 00:10:13] sites across the U.S. and Canada. And what it did was compare two strategies for testing patients with suspicion of coronary disease, symptomatic patients. These patients were randomized to either receive a functional test first, or an atomic test first, and the idea was to see whether providing the functional information or the anatomic information leads to differences in outcomes of these patients.
As you know, the primary paper showed that the health outcomes of these two strategies were similar and not different. Now in this paper here, we took the slightly different approach and we really wanted to see how the results of the tests as they were seen by the [inside 00:11:02] so it was all based on the sight interpretations of these tests. How the results of these tests actually were associated, or were associated with the health outcomes. And so we directly compared categories of CT results, and categories of functional testing results, and how they are related to outcomes. The good news I think is that sight interpretations in real life do actually have prognostic value for both the anatomic or the CT, and also the functional testing, and so findings as significant disease [inaudible 00:11:36] ischemia have in fact similar prognostic value. And we also saw that on the lower end of the findings, so mildly abnormal findings for example, that the ability to see nonobstructive CAD, perhaps if you're a difference maker and identify from additional patients or group of patients that is at risk for [inaudible 00:12:01].
Dr. Leslee Shaw: I think that often times we struggle with negative trial results, if I can put PROMISE in that negative trial results. And here we have a paper that I think really applies clinically. I think it's going to have far-reaching clinical implications. I think if you look at the CTA findings, this is a real world practice. I think there's a simplicity to CTA interpretations that really is amplified in the nice ability to risk stratify. Whereas the functional interpretation, as you both know, is complex. It integrates a lot of factors, wall motion, perfusion imaging, ST segment changes, exertional symptoms, all of that, and I think we see a lot of sight variability in that image interpretation on the ischemia-side of the functional testing arm.
But there's and important finding from this paper, which I think we have seen in bits and pieces prior to this report, and that is that on the CTA side, you had about a third of the patients having pure normal coronaries. So you see that very low risk in that population. But what you see on the functional testing arm is that the event rate in patients with normal studies and in patients with a mildly abnormal study, the event rates were identical, which is fascinating.
And importantly, two thirds of the population on the functional testing arm were in those normal and mildly abnormal subgroups, something like that. And that has important implications for what is in that one third on a CTA side with normal findings versus three quarters? Well I think from this randomized trial, I think we can infer that you're going to have some non-obstructive disease in that population, but you're also going to have non-ischemic obstructive disease.
We know from FFR and all of the angiographic literature that not every obstructive lesion is ischemic. And so on the stress testing side, we have a lot of obstructive disease that potentially is missed. And I think this study really clearly illustrates that limitation of stress testing and it reflects sight variability in imaging and the interpretation. It reflects the patient populations and the struggles with doing stress testing, but also just flat out reflects the ischemic cascade, and what we can expect from an obstructive lesion, or a non-obstructive lesion, that may not elicit ischemia.
So to that extent, I think Udo's paper is just, just far-reaching and really clearly one of the most advanced papers that we have seen in such a long time. From really providing an important message for those imagers and for folks doing stress testing in this country.
Dr. Carolyn Lam: should we then always do anatomic testing first before selective stress testing?
Dr. Udo Hoffmann: The choice of testing is very much I think tied to the population of the patient you're talking about. I think when you follow the literature, 30 years ago when all the classic studies out of [experienced centers 00:18:53] such as Cedar Sinai, were published, the ischemia burden was much higher in the tested population. Back then you had probably a third or 40% of patients who in fact had some abnormality or ischemia on stress testing. One of the findings here in this study, and that is true for both tests, is that the prevalence of severe findings, severe abnormalities, whether ischemia or obstructive disease, is what I found testing is pretty similar, so it's both around 12%, but it is relatively infrequent. And I think that has changed.
And you cannot expect, as Leslee pointed out nicely, it is not expected from a stress test to detect non-obstructive disease that has prognostic value, but doesn't necessarily explain these symptoms that the patient is presenting. So we should not forget that these patients do not come for primarily for prognostic assessment, they come because they're symptomatic. And the primary question is do we find an equivalent that could explain the symptoms of the patient? And only once we are convinced that there's no such equivalent that would for example lead us to further assess the patient for potential reverse [inaudible 00:20:19] therapy, then the second question that can be answered is for the prognostic implication of the test. And I think in this relatively low risk population, this prognostic aspect gains more importance irrelative to the diagnostic aspect.
Dr. Carolyn Lam: I think Leslee made it very clear in her editorial as well, not to forget in essence at the extremes of disease, that both tests, both strategies conveyed similar prognostic information, and it was more for the fine grain teasing apart that perhaps we need to consider very, very carefully what your paper is saying. But at the end of the day, it's about treating the patients for their cardiovascular risk management, isn't it? Recognizing that even if you don't have ischemia, if you've got the risk factors, like you nicely showed, that we should be treating them for the risk factors.
Leslee, want to share some of your thoughts there? You covered that so nicely in your editorial.
Dr. Leslee Shaw: Well I think that's one thing we've seen from PROMISE, SCOT-HEART, and many, many other recent trials as of late, over the last three or four years, is that the stress test is an opportunity not only to assess ischemic burden, or that CTA's not only a test to assess the extent and severity of coronary disease as well as plaque, but it's an opportunity to identify clear, preventive strategies for the patients.
And this is really something that I don't think at least historically within the stress testing community, that we have taken upon ourselves in order to say, "Okay, here we have a symptomatic patient. We not only are going to assess ischemia, but we're going to look at what else they need to do in order for us to guide prevention." I think this is a clear reminder that this is a great opportunity for us to have a bit of a paradigm shift on the diagnostic testing, to take that whole picture if you will of the patient, and really to focus in on prevention because that is a great opportunity, as Udo talked about just a few minutes ago, it's a great opportunity for us to set the patient on the correct course.
The guidelines, as both of you know, focus in on having that diagnostic evaluation and to implement guideline directed medical therapy as a front line examination. This is a great opportunity for us to just use that diagnostic evaluation ad the initiation of appropriate care for the patient, and then to look at symptom burden, recurrent symptoms, the need for additional interventions. But that first step is guideline directed medical therapy for the patient.
Dr. Udo Hoffmann: Continuing on Leslee's excellent point, I think the paper I think is hopefully a starting point to think about randomized trial, because we assume some maybe come to the conclusion, okay, if you have non-obstructive disease, you should be treated with [inaudible 00:23:13] and aspirin. But we don't know that. I think this is really a call for randomized trial. PROMISE was the one, and it was a good trial. It looked at the association of strategy with an outcome. I think one trial that is needed is to look what specific therapeutic decisions based on imaging or based on test diagnostic test findings, would be justified and would potentially lead to improved outcomes. And that is true for both the stress testing and the CT side. So I think this paper shows the opportunities, but I don't think we have the randomized data to exactly define what are the management options for each of these details of the information that these test results deliver us.
Dr. Carolyn Lam:
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. Our featured paper today provides important trial evidence that will guide interventional management of symptomatic femoral artery disease, but first, here's your summary of this week's journal.
The first paper sheds light on the interaction between left ventricular dysfunction and mesenchymal stromal cell activation. First author, Dr. Naftali-Shani. Corresponding author, Dr. Leor and colleagues from Neufeld Cardiac Research Institute in Israel isolated mesenchymal stromal cells from cardiac and subcutaneous fat tissues of mice with left ventricular dysfunction, 28 days after myocardial infarction or sham operation. They further injected mesenchymal stromal cells or saline into the infracted myocardium of mice and evaluated left ventricular remodeling 28 days after myocardial infarction. They found that left ventricular dysfunction switched cardiac mesenchymal stromal cells towards an inflammatory phenotype and that these pro-inflammatory mesenchymal stromal cells contributed to adverse left ventricular remodeling and dysfunction. The inflammatory polarization of cardiac mesenchymal stromal cells by left ventricular dysfunction was mediated by toll-like receptor four. Finally, toll-like receptor four deficiency in mesenchymal stromal cells attenuated their pro-inflammatory activation, improved their reparative properties, graft survival, infarct repair and left ventricular remodeling.
In summary, the environment of the failing and infarcted myocardium drove resident and transplanted mesenchymal stromal cells towards a pro-inflammatory phenotype that restricted their survival and reparative effects in a mechanism mediated by toll-like receptor four. Targeting toll-like receptor four in mesenchymal stromal cells could improve the safety and efficacy of cell therapy in heart failure.
The next study provides evidence that fractional flow reserve or FFR is a useful index for decision-making in real life daily cath lab practice. First author, Dr. Ahn, corresponding author, Dr. Park and colleagues from Heart Institute Asan Medical Center in South Korea, evaluated the prognosis of deferred and revascularized coronary stenosis after FFR measurement in the IRIS-FFR registry of 5,848 prospectively enrolled patients. This large prospective registry showed that the FFR was linearly associated with the risk of cardiac events in deferred lesions. In addition, revascularization for coronary artery stenosis with a low FFR of less than 0.75 was associated with better outcomes than deferral, while for a stenosis with a high FFR of greater than 0.76, medical treatment would be a reasonable and safe strategy. Thus, the authors concluded that FFR may be considered a clinical prognostic index in addition to a physiological quantification for flow-limiting stenosis. These and other issues are discussed in an accompanying editorial by Doctors De Bruyne, Fournier and Barbato.
The next study sheds important insights into a potential disease modifier in pulmonary arterial hypertenstion, and that is vascular endothelial growth factor receptor three, or VEGF receptor three. First author, Dr. Hwangbo, Co-corresponding authors Dr. Chun and Dr. Jin from Yale Cardiovascular Research Center in Connecticut, used a combination of experimental animal models, human patient cells and detailed signaling studies to demonstrate the importance of a novel interaction between bone morphogenetic protein type two receptors, or BMPR2 and VEGF receptor three in regulating the robustness of endothelial bone morphogenic protein signaling response. They demonstrated that the interaction was critical for promoting BMPR2 internalization in response to bone morphogenic protein stimulation. They further showed that genetic deletion of endothelial VEGF receptor three in mice resulted in exacerbation of chronic hypoxia-induced pulmonary hypertension and impaired bone morphogenic protein signaling. Thus, these findings identify VEGF receptor three as a key regulator of endothelial BMPR2 signaling and a potential determinant of pulmonary arterial hypertension penetrance in humans.
The next study tells us that a low-dose drug-coated balloon may be a promising treatment option in symptomatic superficial femoral or popliteal artery disease. Dr. Schroeder and colleagues of the Jewish Hospital in Berlin, Germany, reported results of the ILLUMENATE European Randomized Clinical Trial, which was a prospective randomized multi-center, single-blinded trial, where patients were randomized 3:1 to treatment with a low-dose drug-coated balloon or an uncoated percutaneous transluminal angioplasty balloon. The primary safety endpoint was a composite of freedom from device and procedure-related death through 30 days, and freedom from target limb major amputation and clinically-driven target lesion revascularization through 12 months. The primary effectiveness endpoint was primary patency at 12 months. The main results were that in symptomatic patients, with superficial femoral and/or proximal popliteal artery disease, low-dose, drug-coated balloon was safer and more effective than uncoated percutaneous transluminal angioplasty balloons through follow-up of 12 months. This is discussed as a novel strategy to reduce femoral popliteal restenosis in an accompanying editorial by Doctors Goldsweig and Aronow.
The final study provides important genotype-phenotype correlations of SCN5A mutations in probands with Brugada syndrome. First author, Dr. Yamagata, corresponding author, Dr. Shimizu and colleagues of Nippon Medical School in Tokyo, Japan, studied 415 Japanese Brugada syndrome probands to assess the association between SCN5A mutations and clinical outcomes. During a mean follow-up period of 72 months, the overall cardiac event rate was 2.5% per year. Compared to probands without mutations, probands with SCN5A mutations experienced their first cardiac event at a younger age, had a higher positive rate of late potentials and exhibited longer P-wave, PQ and QRS durations, and had a higher rate of cardiac events, especially when the mutations were located in the pore region of the encoded protein. The conclusion was therefore, that genetic screening for SCN5A mutations among Brugada syndrome probands may be useful for stratifying such patients according to their risk of subsequent cardiac events. Well, that wraps it up for your summaries. Now for our feature discussion.
Our feature paper today is the stuff that really could change guidelines. Now, we're talking about superficial femoral artery disease and its treatment. Unlike most other vascular beds, where stenting is the preferred modality of endovascular revascularization, the optimal therapy for superficial femoral artery disease remain controversial. However, today's paper really adds to our insight and I am so pleased to have the first and corresponding author Dr. Ilka Ott, from German Heart Center in Munich, as well as Dr. Manos Brilakis, Associate Editor, from UT Southwestern. Welcome both.
Dr. Ilka Ott: Welcome.
Dr. Manos Brilakis: Morning.
Dr. Carolyn Lam: Wonderful. So Ilka could you please share what you found?
Dr. Ilka Ott: We already know from previous studies there has been a lot of studies showing the drug-eluting balloon is superior to plain angioplasty in superficial artery disease. So then, in our study, we found that the treatment with the drug-eluting balloon plus stenting was very superior to the balloon angioplasty plus stenting and the directional atherectomy. The primary endpoint we used in the study was an angiographic endpoint. It was diameter of stenosis and this was significantly lower in the patients treated by drug-eluting balloon angioplasty, as compared to the balloon angioplasty and atherectomy group. Moreover, we had a clinical follow-up of 24 months and we found that also the target lesion revascularization was 70% in the group of drug-eluting balloon plus stent as compared to 37% in the balloon angioplasty and stent group, and 53% in the atherectomy group. We found a significant reduction also in the clinical endpoint of TLR at three years.
Dr. Carolyn Lam: Wow Ilka, congratulations, but may I just ask, was there any reason to think that a drug-eluting balloon would not be similarly beneficial as in other vascular beds?
Dr. Ilka Ott: Well, I think is not a novelty of the study. We already know from previous studies that drug-eluting balloon is superior to plain balloon angioplasty so that's not a surprising result. However, in disease of the femoral superficial artery we often have the problems, in particular when we treat complex lesions like along occlusions or along calcified stenosis, that drug-eluting balloon is not sufficient, so you need to also stabilize the lesion to stabilize dissections. You also need to do a stent implantation. Our study now shows that the combination of drug-eluting balloon plus stent is superior than plain balloon angioplasty plus stent. The nice approach is most of the time if you need a stent, if you use drug-eluting balloon and the lesion is stable and you don't need a stent you are glad. This has shown previous studies, however, if you need further treatment and you need to place a stent, we now show that the pretreatment with a drug-eluting balloon is a superior option than just the plain balloon angioplasty.
Dr. Carolyn Lam: Manos, what is your take on these results? Do you think it will impact guidelines?
Dr. Manos Brilakis: First of all, I would like to congratulate Dr. Ott for an excellent study. I think what is particularly important here, is the comparative effectiveness component. We have several studies circulating already about drug-coated balloons, have studies on stents, but we don't have studies addressing the other modalities like atherectomy. Why I was particularly impressed, is I think the study will have a finally an assessment of atherectomy as a primary strategy for calcified lesions and it's interesting that that was not as good efficacy. It was actually tents for worse TLR as compared to plain old balloon angioplasty and stent. Would like to ask Dr. Ott what is your kind thoughts about the alone atherectomy give the results of the study? Are they still doing it or is it falling out of favor?
Dr. Ilka Ott: Yes, I think this is a very important point. I think atherectomy alone is not an appropriate treatment but there are some data that atherectomy in combination with drug-eluting balloon gives much better results, or you may even think about a combination of atherectomy and drug-eluting stent, so it often is the case. This study also raises a lot of questions and gives some thought into further studies. I think in the combination atherectomy might still have its place.
Dr. Carolyn Lam: Could you tell us some of those plans for future studies?
Dr. Ilka Ott: Well, we are just in the initiation phase but I think one also very interesting concept is to compare drug-eluting balloon plus stent to the drug-eluting stents that have been on the market. However, as I said before, there's again the concept if you combine the drug-eluting balloon plus a stent it might be also, from the commercial aspect, better because sometimes you don't need the stent. And then moreover, the drug-eluting stents are much more expensive. It would be interested to see a study like that.
Dr. Carolyn Lam: What about the concern that the superficial femoral artery is subject to a lot of stretching and external compression and it's long and ... Maybe I'm out of date here about the concern of stent fractures and so on. It looks like your study has disproven this, or do you think the follow-up's long enough?
Dr. Ilka Ott: I think the follow-up of two years is quite good, but you're right, it seems like in the superficial femoral artery the restenosis process is much longer and more prolonged. Of course, you would like not to place a stent in the SSA but from the interventional aspect, it's often not possible because if you have a dissection with a limiting the flow, you have to fix that by putting in a stent. Nitinol stents are pretty good these days. Moreover, we have another generation of the woven stents the Supera stents that might also be an interesting point to investigate in comparison to the strategy we now have shown to be superior.
Dr. Manos Brilakis: I think what we need is more studies like this, that they take the other modalities like atherectomy, laser and combine them with what is currently the standard of care, which is drug-coated balloons or drug-coated balloons plus stent, as shared in the study. I just want to congratulate Dr. Ott on her study and encourage future studies from the group. I know the ISAR group is been a phenomenally productive group in coronary intervention and I'm delighted to see they're expanding on the peripheral world.
Dr. Carolyn Lam: I couldn't agree more. Congratulations, once again, for a study that really will impact practice and that we're so proud to be publishing in Circulation.
Listeners, I'm sure you learned as much as me, so please don't forget to tune in next week as well. Thanks.
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. Our featured paper this week confirms the clinical utility of a polygenic risk score of common variants of cardiovascular disease. More soon after this week’s summary of articles.
The first original article describes distinct cell-specific roles for NADPH oxidase, or Nox2, in blood pressure regulation. This paper from first author, Dr. Sag, corresponding author, Dr. Shah, colleagues from King's College London British Heart Foundation Center of Excellence in the United Kingdom. The authors used novel gene modified mouse models to show that Nox2 in myeloid cells modulates basal blood pressure whereas endothelial cell Nox2 is involved in angiotensin II-dependent hypertension. The finding that Nox2 in different cell types has distinct effects on blood pressure, suggest that different diseases conditions may alter blood pressure through effects on Nox2 in different cell types. For example, it is conceivable that the effects on myeloid cells on basal blood pressure may be enhanced in inflammatory settings, whereas endothelial cell Nox2 activation may be more relevant to renin-angiotensin system-dependent hypertension. The current results are therefore relevant to the design of novel therapeutic approaches for hypertension by targeting NADPH oxidases.
The next paper provides a new, more accurate atherosclerotic cardiovascular disease risk prediction tool in familial hypercholesterolemia that may increase the efficiency of care and use of newer lipid lowering therapies. Co-corresponding authors, Dr. Mata and Pérez de Isla, from Hospital Clinicals San Carlos in Madrid, Spain, use data from SAFEHEART, a multicenter, nationwide, long-term prospective cohort study of 2,404 adult patients with molecularly-defined familial hypercholesterolemia and who have followed up for a mean of 5.5 years. They developed a robust risk prediction equation for incident atherosclerotic cardiovascular disease based on the following independent predictors; age, male gender, history of previous atherosclerotic cardiovascular disease, high blood pressure, increased body mass index, active smoking, LDL cholesterol and LPA levels. The new SAFEHEART risk equation performed better with a Harrell C index of 0.81 compared to 0.78 for the modified Framingham's risk equation and 0.8 for the ACC/AHA Pooled Cohort risk Equations. The authors therefore concluded that the risk of incident atherosclerotic cardiovascular disease may be estimated in familiar hypercholesterolemia patients, using simple clinical predictors, and that these findings may improve re-stratification and could be utilized to guide therapy in patients with familiar hypercholesterolemia.
The next study tells us that late gadolinium enhancement cardiovascular magnetic residents identifies patients with dilated cardiomyopathy but without severe left ventricular systolic dysfunction, who are still at high risk of sudden cardiac death. In this study, by first author Dr. Halliday, corresponding author Dr. Pennell, from Royal Brompton Hospital in London, United Kingdom, the authors prospectively investigated the association between mid-wall late gadolinium enhancement and the primary composite outcome of sudden cardiac death or aborted sudden cardiac death, among 399 consecutive referrals with dilated cardiomyopathy and a left ventricular ejection fraction above 40% seen at their center between 2000 and 2011. These patients were followed for a median of 4.6 years. 17.8% of patients with late gadolinium enhancement reached the pre-specified end point, compared to only 2.3% without late gadolinium enhancement.
Furthermore, following adjustment, late gadolinium enhancement predicted the composite end point, with a hazards ratio of 9.3. Thus, patients with dilated cardiomyopathy and mid-wall late gadolinium enhancement, and mild or moderate reductions of left ventricular ejection fraction should still be recognized as having a high risk of sudden cardiac death. This is important because these patients are not currently offered ICDs for the primary prevention of sudden cardiac death, based on current guidelines. Due to the low competing risk of death from non-sudden causes, it is possible that these patients will benefit from ICD implantation, but randomized trials are now required. These issues are discussed in an accompanying editorial from Dr. Markman of Johns Hopkins University, and Dr. Nazarian, Hospital of University of Pennsylvania.
The next study enhances our understanding of the role of immunity in hypertension. Now, the innate antigen-presenting cells and adaptive immune T-cells have long been implicated in the development of hypertension, however, the T-lymphocytes subsets involved in the pathophysiology of hypertension remain unclear. A small subset of innate-like T-cells expressing the gamma-delta T-cell receptor, rather than the more commonly expressed alpha-beta T-cell receptor, could play a role, and these were the focus in today's paper by first author Dr. Caillon, corresponding author Dr. Schiffrin, and colleagues from Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montreal, Canada. In experimental models, the authors showed than angiotensin-2 infusion increased gamma-delta T-cell numbers and activation in the spleen of wall tite mice, as well as in increased the systolic blood pressure, and decreased mesentric artery endothelial function in wild type mice, but not in mice devoid of gamma-delta T-cells, or in mice depleted of gamma-delta T-cells by depleting antibody injections.
Furthermore, angiotensin-2 induced T-cell activation in the spleen and peri-vascular adipose tissue was blunted in null mice. In humans, there was an association between systolic blood pressure and gamma-delta T-cells. In summary, this is the first in-vivo demonstration that gamma-delta T-cells, a subpopulation of T-cells, play a fundamental role in the development of hypertension and vascular damage. These results will help design novel treatments to limit the progression of hypertension and vascular damage.
The final paper describes a novel multi-modality strategy for cardiovascular risk assessment. Dr. de Lemos and colleagues from UT Southwestern Medical Center in Dallas, Texas, hypothesized that a strategy combining promising biomarkers across multiple different testing modalities would improve global and atherosclerotic cardiovascular disease risk assessments among individuals without known cardiovascular disease. These modalities included: left ventricular hypertrophy by electrocardiogram, coronary artery calcium, N-terminal pro B-type natriuretic peptide, high sensitivity cardiac troponin-T, and high sensitivity C-reactive protein.
Using data from 6,621 individuals of the multi-ethnic study of atherosclerosis, or MESA, as well as 2,202 individuals from the Dallas heart study, the authors evaluated the association of test results with the global composite cardiovascular disease outcome, and that would include cardiovascular death, myocardial infarction, stroke, coronary or periphery revascularization, incident heart failure or atrial fibrillation, as well as atherosclerotic cardiovascular disease outcomes, which included fatal or non-fatal myocardial infarction or stroke. Over more than 10 years of follow-up, the authors found that each test result was independently associated with the global composite cardiovascular disease events in MESA. When the 5 tests were added to a base model, the C statistic improved, that was significant integrated discrimination improvement, and net reclassification improvement, and the model was well-calibrated. Using a simple integer score counting the number of abnormal tests, they showed that global cardiovascular disease risk increased with increasing score in a graded fashion. These findings were replicated in the Dallas heart study, and were similar for the atherosclerotic cardiovascular disease outcome.
This study therefore supports the potential value of a multi-modality testing strategy in selected individuals, in whom additional risk stratification is desired, beyond measurement of traditional atherosclerosis risk factors. The authors do highlight that additional studies are needed to validate the present findings, determine the optimal approach to implementation, and address direct and indirect cost implications of the additional testing.
Well, that wraps it up for your summaries. Now for our feature discussion.
Our feature paper today tells us that a polygenic risk score identifies a group of individuals with a higher burden of atherosclerosis, and greater relative benefit from statin therapy in the primary prevention setting. But perhaps even more significant, is that it addresses the fact that even relatively small effect sizes of common snips gathered together in a genetic risk score may have clinical utility in the prediction of cardiovascular disease, and to discuss this I'm so pleased to have the first author, Dr. Pradeep Natarajan from Massachusetts General Hospital, and Dr. Anand Rohatgi, associate editor from UT Southwestern. Welcome, gentlemen.
Dr. Pradeep Natarajan: Thank you very much, Carolyn.
Dr. Anand Rohatgi: Thank you, Carolyn.
Dr. Carolyn Lam: Pradeep, could you start by telling us what you did? This was a tour de force, please.
Dr. Pradeep Natarajan: Yeah, thanks so much for the invitation and the enthusiasm. So, briefly, large-scale, genome-wide association studies have discovered genetic risk variants in the population that individually associate with coronary disease risk. Many others have shown that an aggregate of these genetic risk variants predisposes to an increased risk for coronary disease by about 60%. But we sought to, with this study, understand how primary preventive statins could influence that risk, and whether these insights could be helpful in refining statin eligibility. So, among the individual variants that had been associated with coronary disease, we developed a risk score. This encapsulated 57 individual genetic variants. This risk score is independent of traditional cardiovascular risk factors, and identified individuals with a greater burden of sub-clinical atherosclerosis, defined as coronary artery calcium and carotid plaque, and two observational cohorts in individuals with a greater absolute and relative benefit from statin therapy from a subgroup analysis within the WOSCOPS clinical trial.
What we were surprised by is that the conventional wisdom, that all previously described subgroups within statin trials had the same relative benefit, and statins per unit of alveol cholesterol lowering. So, about 20 to 25% lowering of risk per 40mg per deciliter of alveol cholesterol. So we clinically identify individuals who just start out at high absolute risk, assume that the relative benefit will be the same across everyone, and optimize the number needed to treat simply by just finding individuals at high risk. But, here we didn't see the expected 20 to 25% lowering in the high genetic risk group, we saw actually a 44% relative risk reduction for the same lowering of alveol cholesterol. And we have now observed that across three different clinical trials, and these individuals are at high baseline risk, so this translates into an even more optimized number needed to treat, and really the opportunity to identify individuals earlier with an age independent biomarker.
Dr. Carolyn Lam: That's really cool, in fact, the number needed to treat in the high-risk score group was impressively low at 13.
Dr. Pradeep Natarajan: That's correct. Now, overall in the WOSCOPS trial, if you look at all individuals, it's about 38, so it is a high risk primary preventive group of men with, you know, substantial hyperlipidemia, but if you look at at least a relative difference between the two, going from 38 to 13, that's about a three-fold improvement of the number needed to treat.
Dr. Carolyn Lam: You know, what you said about it not correlating with exactly what you expected with the drop in LDL and so on, does that mean that this genetic risk score, that a lot of the snips are probably associated with LDL levels, but that a lot of them may be giving more information beyond LDL? Is that what it means?
Dr. Pradeep Natarajan: Yeah, you know, it's interesting. Most of the genetic variants that are associated with coronary disease actually do not seem to clearly influence traditional cardiovascular risk factors. The latest best estimate of that is about 39% of them associate with traditional cardiovascular risk factors, and then a subset with LDL cholesterol. So the aggregate score actually does not associate with traditional risk factors, and including with LDL cholesterol.
Dr. Carolyn Lam: Wow, and Anand, I'm sure we had so many discussions with the editors about the paper. Could you share some thoughts?
Dr. Anand Rohatgi: Yes, Carolyn. Circulation as a journal represents the best in cardiovascular science, and we're always interested in the highest-level articles related to atherosclerotic cardiovascular disease. So, when we received this manuscript from Pradeep and Sekar’s group, really leaders in the field, we were really excited, and as we went through the review process we got even more excited because it, as you said, Carolyn, it really was a tour de force, it was a high-quality article and it combined multiple things, and that's what we're really interested in seeing at Circulation, is combining several aspects, in this case genetics, sub-clinical atherosclerotic imaging, and also treatment effect.
And, you know, it's interesting because several recent manuscripts looking at genetic risk scores, they were associated with coronary disease but it wasn't clear that they were improving what we call risk prediction performance indices, at least enough to meet the bar of incorporating them into guideline-type recommendations. So I think the field wasn't sure how to move forwards with this type of information, but now I think this study really demonstrates that this type of risk score, this genetic risk score, really can inform treatment decisions in a big way. And so we were really excited to talk about that and then see it move forward.
Dr. Carolyn Lam: So a question for both of you now. Can these data be extrapolated to other cohorts of patients? I mean, WOSCOPS was predominantly white, and all were males, right? So, Pradeep, would you like to take that first?
Dr. Pradeep Natarajan: That's an excellent observation, and I think ... A clear limitation in the field, but an outstanding question that I think can be addressed going forwards. So, the main challenge is that the epidemiological cohorts that were used for genetic analysis largely have been of European ancestry, and we know that genetic background and a variety of non-genetic factors influence cardiovascular disease risk, so in genetic analysis of European individuals the influencers of coronary disease risk may not influence cardiovascular disease the same in non-European ethnicities. And, you know, we've done some work of this specifically in African-Americans, and there are some differences. You know, African-Americans are largely mixed of both African and European ancestry, some of that seems to also influence how you interpret the cardiovascular genetic risk score.
Ideally you would have a risk score that is not influenced by the genetic background, and so the next step going forward are one to look to see how well this risk score predicts in non-European ancestry, because, obviously, not as much statin clinical trial information in non-European cohorts, but I think looking at the treatment effect in non-Europeans will be important. And then, you know, the third step is we and others are participating in several now large ongoing efforts to really define what the genetic influences are in non-European ancestries, and I think that will be a very important next step that's really critical before the clinical implementation.
Dr. Carolyn Lam: Yeah, talking to you from Asia, that's music to my ears, obviously. Anand, did you have any questions for Pradeep or anything else to add about the paper?
Dr. Anand Rohatgi: Yeah, I wanted to add one or two comments. One thing that this study demonstrates is that the genetic risk scores, whether they relate to traditional risk factors or lipids, that doesn't necessarily translate to what it might mean in terms of treatment benefit, and so I think that concept is generalizable and now it needs to be tested in other ethnicities, other types of subgroups, but I think you can disentangle a relationship with risk factors and lipids to its treatment effect and this study really nicely shows that.
And I think just to take a step back, we know statins work in intermediate-risk patients, maybe even low-risk patients with the most recent studies, but at a public policy level, and just as a cognition, we really want to narrow the focus, it's something called precision medicine that the American Heart Association is promoting as a concept, and I think that this study really demonstrates that here we have now another tool that can reduce this number needed to treat, make this choice for statins more precise, maximizing the benefits and limiting cost. So, I think that concept is very generalizable, it needs to be tested now in multiple populations, like Pradeep said, and I guess one of the questions I had had for the authors is: how do we incorporate this finding that they saw with sub-clinical atherosclerosis, which we thought was very fascinating among the editors at Circulation, that now they're also linking with sub-clinical atherosclerosis, is that something that the investigators think needs to be pursued further? Would that be something that would be used clinically as well?
Dr. Pradeep Natarajan: I think there are lots of opportunities for this going forward, you know, in prior work we've done the genetic architecture for clinical coronary disease is actually very similar to sub-clinical coronary disease, and there are many influences for sub-clinical coronary disease, and clinical coronary-disease, that are both genetic and environmental, and the aggregate effect from the polygenic risk on sub-clinical atherosclerosis suggests that it's obviously not absolute and there are other factors that influence sub-clinical atherosclerosis.
Dr. Carolyn Lam: Well, listeners, you heard it right here. Thank you for joining us this week, tell all your friends about it, and don't forget to tune in again next week.
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. In just a moment we'll take a deep dive into hemo-compatibility-related outcomes in the MOMENTUM 3 trial of a fully magnetically levitated pump in advanced heart failure. But first, here's your summary of this week's journal.
The first paper sheds light on the biological mechanisms underlying cardioprotective effects of the Mediterranean diet. First author, Dr. Wang, corresponding author Dr. Hu and colleagues of Harvard, TH Chan, School of Public Health in Boston, Massachusetts studied 980 participants from the PREDIMED Trial including 230 incident cases of cardiovascular disease and 787 randomly selected participants at baseline followed up for 7.4 years.
Participants were randomized to a Mediterranean diet supplemented with extra virgin olive oil, a Mediterranean diet supplemented with nuts, or a controlled diet. Plasma ceramide concentrations were measured and the primary outcome was a composition of non-fatal acute myocardial infarction, non-fatal stroke or cardiovascular death.
The authors found a novel positive association between baseline plasma ceramide levels and incident cardiovascular disease. In addition, the association between baseline ceramides and incident cardiovascular disease varied significantly by treatment groups where a Mediterranean dietary intervention appeared to mitigate the potential deleterious effects of elevated plasma ceramide concentrations on cardiovascular disease.
These findings, therefore, strengthen the evidence base for recommending the Mediterranean diet for cardiovascular disease prevention and suggest that plasma ceramides have the potential to serve as markers of future cardiovascular disease risk.
The next paper describes a novel therapeutic approach against hypertensive cardiac remodeling and provides the first evidence of the cardio protective effect of cardiofibroblast-specific activating transcription factor 3 or ATF3. In this study from first author Dr. Li, co-corresponding authors, Dr. Du from Beijing Anzhen Hospital in China, and Dr. Ma from Thomas Jefferson University in Philadelphia and colleagues, the authors used a discovery-driven unbiased approach to identify increased ATF3 expression in mirroring hypertensive hearts and the human hypertrophic heart, expressed primarily by cardiac fibroblast cells. ATF3 knockout markedly exaggerated the hypertensive ventricular remodeling, a state rescued by lentivirus mediated microRNA aided cardiac fibroblast selective ATF3 over-expression.
Conversely, cardiac fibroblast specific ATF3 over-expression significantly ameliorated ventricular remodeling and heart failure. The authors further identified MAP2K3 as a novel ATF3 target, and that p38 was the downstream molecule of MAP2K3, mediating the profibrotic hypertrophic effects in ATF3 knockout animals.
In summary, this study provides the first evidence that ATF3 up-regulation in cardiac fibroblasts in response to hypertensive stimuli, protects the heart by suppressing MAP2K3 expression, and subsequently p38 TGF-beta signaling. Thus, identifying molecules mimicking endogenous ligands or inhibiting microRNA that down-regulate ATF3 expression, may represent novel therapeutic approaches against hypertensive cardiac remodeling. These, and other issues, are discussed in an accompanying editorial by Dr. Jennifer Davis of University of Washington.
The next paper tells us that clinical frailty score may need to be part of the pre-operative assessment of patients undergoing transcatheter aortic valve replacement, or TAVR. First author, Dr. Shimura, corresponding author, Dr. Yamamoto and colleagues of Toyohashi Heart Center in Japan, utilized the optimized catheter valvular intervention or OCEAN Japanese Multicenter Registry of 1215 patients undergoing TAVR and found that clinical frailty score correlated with other markers of frailty, such as body mass index, albumin, gait speed and grip strength. Furthermore, the clinical frailty score was an independent predictive factor of increased late-cumulative mortality risk. Thus, in addition to reflecting the degree of frailty, the clinical implications of these findings are discussed in an accompanying editorial by Dr. Jonathan Afilalo from McGill University in Montreal.
In the final study, we learned that long-term anabolic androgenic steroid use may be associated with myocardial dysfunction and accelerated coronary atherosclerosis. Dr. Baggish and colleagues from Massachusetts General Hospital in Boston, used a cross-sectional cohort design of 140 experienced male weight lifters, age 34-54 years, comprising 86 men reporting at least two years of cumulative lifetime anabolic androgenic steroid use, and 54 non-using men. Compared to non-users, steroid users demonstrated relatively reduced left ventricular systolic function and diastolic function on transthoracic echocardiography. Furthermore, steroid users demonstrated higher coronary artery plaque volume on coronary CT angiography compared to non-users. In summary, this is the first large controlled study of its type to demonstrate that long-term anabolic androgenic steroid use is associated with both systolic and diastolic myocardial dysfunction, as well as coronary atherosclerosis. Thus, when clinicians encounter young or middle-aged men who exhibit evidence of unexplained left ventricular dysfunction or premature coronary artery disease, the possibility of cardiotoxicity due to long-term anabolic androgenic steroid use should be considered in the differential diagnosis.
Well, those were your summaries. Now, let's move on to our featured discussion.
For our featured discussion today, we are actually reviewing a secondary analysis of the MOMENTUM 3 Trial, which is a multicenter study of the mag lev technology in patients undergoing mechanical circulatory support, with the HeartMate 3. And to discuss today's findings I'm so pleased to have the corresponding author, Dr. Mandeep Mehra from Brigham and Women's Hospital in Boston, Massachusetts, as well as Dr. Biykem Bozkurt, Associate Editor from Houston, Texas.
Welcome Mandeep and Biykem.
Dr. Mandeep Mehra: Thank you. It's a pleasure to be with you all.
Dr. Biykem Bozkurt: Thank you.
Dr. Carolyn Lam: Let's start by getting a few definitions right, shall we, just for our audience. This specific article, and congratulations Mandeep, it's just so great, it speaks of hemo-compatibility-related outcomes. Could you start by telling us what that is, and maybe reminding us what the original MOMENTUM 3 short-term results showed.
Dr. Mandeep Mehra: Sure. As our listeners are aware, left ventricular assist devices have really transformed the management of refractory advanced heart failure, by the introduction of a form of flow, called continuous flow, in the devices, which tend to render patients, relatively low pulsatiles to non-pulsatile. Now what we've seen is that the interface between this very unnatural physiology from continuous flow in concert with the patient's biology tends to create a constellation of problems that we sort of refer to as hemo-compatibility-related adverse events.
For example, we have seen a very curious development of recurrent gastrointestinal bleeds that tend to occur in a manner similar to what was observed with critical aortic stenosis, the so-called Heyde's Syndrome. Similarly we see stroke-related problems and we also see evidence of thrombosis that can sometimes develop within the pump. So we refer to the conglomeration of these unique complications that arise from the abnormal interface between the device and the patient as hemo-compatibility-related adverse events.
Dr. Carolyn Lam: And this is a secondary analysis, a six-month secondary analysis, right? So could you give a little bit of background of why you would hypothesize that these events might be different with the HeartMate 3 versus 2? I mean, it's quite unique that we're going back to creating a pulse.
Dr. Mandeep Mehra: Yes. Let me fist define for our audience what the MOMENTUM 3 Trial was designed to initially do, and is still doing. MOMENTUM 3 is a randomized controlled trial of two devices: one, a conventionally available continuous flow device called the HeartMate 2, and the second device, the novel pump called the HeartMate 3. The HeartMate 3 is a pump that took two decades to engineer. And it took that long because it is very unique, based on the following principles.
First, it's a small profile, so the entire pump can be placed intrathoracically. Second is that the way in which it moves blood, its rotor, is fully magnetically levitated, which means that it has no friction when it rotates. The third is that despite its small profile, this device has wide blood flow gaps, meaning that as blood is moving in this centrifugal flow pump, it does not expose the blood elements to as much of sheer stress as one sees with other conventionally available devices. And then finally, what this device has uniquely is a intrinsic pulse, and what that means is that we program this device in a fixed program to actually ramp its speed up and ramp it down so that it creates an intrinsic pulse of about 30 beats per minute, which is engineering-wise designed to improve pump wash out; that's the intention.
So the MOMENTUM 3 Trial was constructed to really compare these two devices and we recently reported, on the primary end point of the six-month outcomes of this trial. And the trial primary end point was set at survival free of a disabling stroke, or the need for re-operation because of pump malfunction. And what we found was that this pump, the HeartMate 3, clearly met its non-inferiority end point, versus the HeartMate 2, but also demonstrated superiority on the primary end point at six months. We were certainly not expecting to see superiority at this early time point, but we were very fortunate to see that.
Now what is unique about this is that for the first time ever, we saw no cases of suspected or manifest established pump thrombosis, as a result of de novo pump thrombosis requiring re-operations with the HeartMate 3 device. And this is a frequency of about 10% that we normally observe with pumps. That is one in 10 pumps will clot off within about six months, and require re-operation. So we were very gratified to see this observation in the short-term data of the primary MOMENTUM 3 database.
Now as a result of that observation, Carolyn, we thought that the hard end points, as are typically adjudicated for the primary basis of these clinical trials, missed the entire constellation of hemo-compatibility-related outcomes because these are patients who develop both bleeding and clotting complications. And the net burden of hemo-compatibility is not entirely available for review, which is the basis of this important secondary analysis that was published in Circulation.
Dr. Carolyn Lam: What striking findings. So tell us the bottom line.
Dr. Mandeep Mehra: What we found in the secondary analysis was evidence that the burden of hemo-compatibility-related adverse events is lower in patients with the HeartMate 3, compared to the HeartMate 2 device. And that was the basis of the bottom line that we found.
In particular, we knew that there were no episodes of de novo pump thrombosis with the HeartMate 3, but we also found that there was evidence of a reduction in non-disabling strokes with the HeartMate 3 device. So we now have evidence that thrombotic complications, minor strokes, as well as pump thrombosis, seem to be abrogated by this new pump.
What we should keep in mind, however, is that this is still early data from the ongoing MOMENTUM 3 Trial, and the trial is actually designed to enroll and observe over a thousand patients, over two years. And we are basically showing in this a very early look at six months of about 300 of these patients. And so that needs to be kept in mind. But we are extremely encouraged by these early trends suggesting that we may have started to break the issues related to the barriers of implementation of such therapy in the hemo-compatibility domain.
Dr. Carolyn Lam: Yeah, and as a heart failure doc, I can tell you that I share that excitement and I know that Biykem does too, as did the editors.
Biykem, tell us a little bit about what we talked about as editors about this paper.
Dr. Biykem Bozkurt: Indeed. Mandeep, the hemo-compatibility concept which is being addressed in this new publication is quite novel and is exciting, and addresses the continual spectrum of the pathology, ranging from the GI bleed, to the stroke spectrum. The question I have, in this study, the overall scores were not different in the absolute number that we saw as a score from the hemo-compatibility ranking.
Do you think we would continue to use this approach as a quantitative score, given the fact that there may be bidirectional impact from different devices on the different spectrum, especially with the recognition that HeartMate 3 seemed to be protective against the thrombotic, perhaps events, or should we use it more of a qualitative score card looking at which perhaps spectrum the device tends to be a little bit more risky or beneficial. So shall we color code this score and try to perhaps focus on the spectrum of thrombosis versus bleeding and then try to strategize?
Dr. Mandeep Mehra: Thank you for that very erudite question, Biykem. You hit right at the heart of the matter. So let me make a few comments about that. The first issue is that so far, the field has not had a clear definition of hemo-compatibility. Hemo-compatibility has been more of a engineering term. When someone said hemo-compatibility, they thought of biomaterials, rather than a clinical definition of hemo-compatibility. So for the first time, we have actually introduced the term hemo-compatibility into the lexicon of definition, managing patients with LVAD, so that's one important point.
The second important point is that we, until this day, until this analysis, have not had the ability to really provide people with a full picture of the entire burden of experience of hemo-compatibility-related complications that an individual patient experiences as they are on this device, because you know that patient's going to have a GI bleed, and then they may have a stroke, because we may change, dynamically we may change anticoagulation for instance if someone has one event then the other, and the traditional way in which studies are done, hey do not give you a clear picture into the burden of hemo-compatibility. So the most innovative thing about this clinical hemo-compatibility definition, is that we've not introduced a score that reflects the burden of disease, and we have also created tiers of severity of the burden of disease experience into three quantitative tiers that include various subsets which are hierarchal.
So for example, is one gastrointestinal bleeding the same as non-disabling stroke? Well, no. One gastrointestinal bleeding may be a milder form a hemo-compatibility-related problem. So our early look at this clearly shows that survival free of a hemo-compatibility-related event is clearly lower in the patients with a HeartMate 3. However, as you astutely pointed out, when you examine purely the burden of hemo-compatibility-related complications experienced by the survivors, one actually sees a trend in favor of the HeartMate 3, but not a statistically significant difference, largely because we have not yet abrogated problems related to bleeding complications on the side of the hemo-compatibility.
Why is that? Well, it's because we still treat all patients in both groups with the HeartMate 2 or the HeartMate 3 with the same intensity of anticoagulation. What this sort of data points out to us in the future, first of all, is that it allows us to compare apples to apples, as we are looking at different device platforms, that's number one. Second is it gives a much more robust look into the total patient experience. And third, it actually gives us insight into whether altering one component of the equation, so let's say there's a bleeder, if you actually react to that clinically, will you start to see problems on the clotting side.
Dr. Biykem Bozkurt: This is a very, very important study that addresses the whole spectrum of hemo-compatibility in a more comprehensive fashion, and also points out perhaps the differences that we see in overall others, centrifugal flow, left ventricular assists, support systems such as the Heartware HVAD study that showed increase in hemorrhagic stroke, especially hemorrhagic stroke in the first six months in the ENDURANCE Trial, whereas the HeartMate 3 has shown in the MOMENTUM 3 publication, as well as the Circulation secondary end point study demonstrates a reduction in disabling strokes and absence of any pump thrombosis.
So there are differences, despite both of the pumps are centrifugal, there are differences in the profile, and the spectrum of the risk and hemo-compatibility. And one other interesting finding from this study is that the predictors for hemo-compatibility outcomes are complementary to what has been known in the sense that lower antiplatelet and anticoagulation management strategies are associated with increased risk of hemo-compatibility adverse events.
And surprisingly, the control of blood pressure did not appear to correlate with the hemo-compatibility outcomes. So from that perspective, it differs from the ENDURANCE Trial where the uncontrolled blood pressure or hypertension was associated with hemorrhagic strokes, in the ENDURANCE Trial, whereas in the MOMENTUM 3, the blood pressure did not appear to correlate with the hemo-compatibility outcomes or pump thrombosis.
So these are very interesting findings and I think are complementary to the evolving field of the risk benefit ratios in patients with LVAD support. And from that perspective, we in Circulation felt that this will be a very valuable publication for our readership as well as for the whole heart failure and transplant community.
Dr. Carolyn Lam: Thank you, so much for joining us today, don't forget to tune in next week.
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. Carlolyn Lam, associate editor from the National Heart Center, and Duke National University of Singapore. What's the link between DPP4 and aortic valve calcification? Well, to find out, keep listening because we'll be discussing this and an important new paper right after these summaries.
The first original paper in this issue tells us that high sensitivity Troponin I, may have a role in personalizing preventive strategies in patients with Type II Diabetes. Dr. Cavender and colleagues from University of North Carolina, Chapel Hill, sought to describe the relationship between changes in high sensitivity Troponin I and cardiovascular outcomes in the EXAMINE phase 3B trial, which was designed to evaluate the cardiovascular safety of alogliptin. The current analysis was restricted to patients, randomized 30 days or more after the qualifying acute coronary syndrome event, and high sensitivity Troponin I was measured using the Abbot Architect Assay at baseline and six months.
The authors found that high sensitivity Troponin I was detectable in the vast majority - 93% of patients with Type II Diabetes, stabilized within 30 days after acute coronary syndrome. One in six of these patients had high sensitivity Troponin I levels above the 99th percentile upper reference limit. High sensitivity Troponin I had a strong graded relationship with the incidence of subsequent major cardiovascular events.
Changes in high sensitivity Troponin I as small as two to six nanograms per liter over six months, were associated with a heightened risk of adverse outcomes. Particularly cardiovascular death and heart failure. Alogliptin neither increased nor decreased the risk of cardiovascular events in a high risk cohort of patients with elevated high sensitivity Troponin I levels. These findings therefore imply that serial measurements of high sensitivity Troponin may have a role in preventive strategies, either by intensifying or prolonging therapies in patients at high risk or reducing or shortening therapies in patients at low risk of cardiovascular events.
The next paper describes the effects of Pioglitazone on cardiac outcomes after ischemic stroke or transient ischemic attack in patients with insulin resistance without diabetes in the IRIS trial, which stands for Insulin Resistance Intervention after Stroke. As a reminder, the IRIS trial compared the effects of Pioglitazone with placebo on major cardiovascular events after stroke or transient ischemic attack, in patients without diabetes but who had evidence of insulin resistance. And it showed that Pioglitazone improved insulin resistance, prevented diabetes, improved CRP and reduced fatal and non-fatal stroke or myocardial infarction.
In the current paper, by Dr. Young and colleagues from Yale Cardiovascular Research Center in New Haven, Connecticut, the authors performed a secondary analysis of IRIS and examined the effect of Pioglitazone on acute coronary syndromes, mainly myocardial infarction or unstable angina. They found that Pioglitazone reduced the risk of these events by 29%, with benefit emerging after two years of treatment. Furthermore, Pioglitazone reduced the incidence of Type I myocardial infarction with a neutral effect on Type II myocardial infarction. In summary, among patients with insulin resistance without diabetes, Pioglitazone reduced the risk of acute coronary syndromes after a recent cerebrovascular event, and may serve as a useful secondary prevention therapy in addition to statins, aspirin, and other established treatments.
The next study tells us that immune complexes may be an important biomarker in the risk stratification of Antiphospholipid Syndrome. Now recall that Antiphospholipid Syndrome is characterized by recurrent thrombosis in patients with Antiphospholipid predictive antibodies. However, the predictive value of the presence of Antiphospholipid auto antibodies is low. And new markers are needed to identify carriers at higher risk.
In the current study by Dr. Serrano and colleagues from Madrid, Spain, the authors performed a historical cohort follow up study based on the Magnum 12 plus 12 cohort, that included all patients who had received a kidney transplant in their hospital in a 12 year period from 2000 to 2011. Sera used for the analysis were collected in the 24 hours before the kidney transplant surgery, and used to measure circulating immune complexes of immunoglobulin A bound to beta II glycoprotein I.
The authors then investigated the possible association of these immune complexes with thrombosis, graft thrombosis and graft loss in the six months following kidney transplant. They found that in patients with the immunoglobulin A isotope antiphospholipid antibodies, the presence of circulating immune complexes of immunoglobulin A bound to beta II glycoprotein I, pre transplant, was associated with acute thrombotic events. Patients positive for the immune complexes had a much higher risk of developing post transplant thrombotic events, and higher risk of graft thrombosis mediated graft loss. On the other hand, complex negative patients had the same thrombosis risk as the control population. These findings imply that treatment to prevent thrombosis should focus mainly on the immune complex positive patients in this setting.
The final paper addresses the issue that public reporting of PCI Outcomes may create disincentives for physicians to provide care for critically ill patients, particularly at institutions with worse clinical outcomes. In this study from first author, Dr. Waldo from the VA Eastern Colorado Health Care System in Denver, Colorado, corresponding author, Dr. Yeh from Beth Israel Deaconess Medical Center in Boston, Massachusetts, and colleagues. The authors used state reports to identify 31 out of 86 hospitals that were recognized as negative PCI outliers in two states: Massachusetts and New York, from 2002 to 2012.
They sought to evaluate the procedural management and in hospital outcomes of patients treated for acute myocardial infarction before and after a hospital had been publicly identified as the negative outlier. They found that outlier facilities were larger, treating more acute myocardial infarction patients, and performed more PCI's than non outlier hospital. The rates of percutaneous revascularization increased similarly at outlier and non outlier institutions after report of the outlier status. After outlier designation, the in hospital mortality declined at the outlier institutions to a greater extent than was observed at the non outlier facilities. Thus, public reporting of outlier status may prompt outlier facilities to improve case selection, and employ systems improvements that optimize patient care, and improve in hospital mortality among patients with myocardial infarctions.
We are going to have such a fun discussion in today's feature paper. Have you ever wondered what does dipeptidyl peptidase-4, or DPP4 have to do with aortic valve calcification? Well, you're about to learn, because in today's paper we actually learn that DPP4 inhibitors, which you might recognize from diabetes, you know drugs such as sitagliptin, could serve a potential therapeutic target in aortic valve disease. To tell us about it and discuss it, we have corresponding author, Dr. Jae-Kwan Song] from Asan Medical Center in Seoul, South Korea, as well as Dr. Thomas Eschenhagen, Associate Editor from University Hospital Hamburg Eppendorf in Germany. Welcome, gentlemen.
Dr. Jae-Kwan Song: Hi.
Dr. Thomas Eschenhagen: Hi.
Dr. Carolyn Lam: Fascinating paper. I have to congratulate you first and foremost, but please tell us, what inspired you to look at DPP4 in aortic valve disease.
Dr. Jae-Kwan Song: Yeah, actually as a clinician, I think there is two issues. One is the prevalence of calcific aortic valve disease is increasing rapidly in the developed and also developing countries. The second important issue is that we do not have effective medical treatment option. So I will say that the medical treatment of calcific aortic valve disease is a typical example of unmet clinical needs to serve this kind of troubled scientific issues, our team have focused on the reciprocal interaction between endothelial cells and interstitial cells. Because this potential mechanism was well reported by other investigators that the interaction between two cells are very critical for maintaining aortic valve tissues. So first we started with Enos knockout mouse, to go over what's going on in the aortic valve in the models. In the human tissues in patient with calcific aortic valve disease, we have found that DPP4 is specifically activated. That's the beginning of our study.
Dr. Carolyn Lam: Could you please explain to those of us who don't do basic science research everyday, I mean, your study involves tissues both from humans and mirroring models. Could you explain it very simply what you did and what you found?
Dr. Jae-Kwan Song: Yes, in the Enos Knockout mouse, we have found that those mouse showed very strong calcification process compared to the live animals. What is the mechanism of this enhanced calcification in this mouse? And we found that the loss of endothelial function is critical, and then we found that DPP4 is actively involved in the calcification process. The first test we have done is the isolation of developed interstitial cells. And then we focused on osteogenic transformation over this valvular interstitial cell both in the Enos Knockout mouse, and the human developing interstitial cells. So we have found that the endothelial dysfunction activates the DPP4 activity in these tissues, which resulted in the increase osteogenic transformation of developed interstitial cell. So that's the beginning of our observation.
Dr. Carolyn Lam: And could you describe what you did subsequently to prove the whole mechanism?
Dr. Jae-Kwan Song: As you know the DPP4 has many substrates including many peptides involved in glucose metabolism, so the hardest part of our study is what is the molecule target, or associated with DPP4 in the pathologic process of calcification in developing interstitial cells. We tested many different substrates known to the potential targets of DPP4, and we have found specifically insulin-like growth factor-1 (IGF-1) is the key proponent of all this process. With further study, we found that the DPP4 cleaves or inactivates or decrease IGF1 activity in the valvular interstitial cell, and in the normal status IGF1 is a very critical to protect osteoblastic transformation of valvular interstitial cell. We have found that the DP4 and IGF1 exercises key therapeutic target, and the key molecules involved in valvular calcification. As you know we do have a DP4 inhibitors, which were successfully clinically to reduce the diabetes control. So it's very easy to test the DP4 inhibitors in animal models. Both in the Enos Knockout mouse, and we also developed in the calcific aortic valve disease using some treatment, including Vitamin D and hypercholesterol and diet the in vivo experiment showed that [inaudible 00:13:58] inhibitors effectively prevented the development of calcification and prevented the development of calcification and prevented the developement of calcific aortic disease. This the main finding of our study.
Dr. Carolyn Lam: That is so fascinating, and really especially what you just said, that sitagliptin in this rabbit model prevented calcific aortic valve disease with the concurrent increase in plasma IGF1 levels in line with the DPP4 inhibition. That is just such a beautiful piece of work, congratulations. And congratulations Thomas on managing such a nice paper. Take us under the hood about the discussions that happened with the editors. Surely you recognized the translational impact. What do you think? Is it time to reposition DPP4 inhibitors?
Dr. Thomas Eschenhagen: We and the reviewers like the paper because first of all it describes a new, interesting biological mechanism. If we are done, and we like that it uses human samples, but also this treatment in two different animal models. This together, really makes it a strong paper, we've found perfectly suitable for Circulation. As you said Carolyn, the translation perspective is fascinating. Obviously it's very early days. There is no specific evidence yet from patients. But that could, in patients, take actually very very long. Even the big studies already been done with sitagliptin and other DPP4 inhibitors, that don't show a signal in this direction yet, but I would say that could still happen, and maybe in the long term, all of the cardiologists putting all this stuff in German it's call TAVS, in America it's called TAVR does not work anymore, obviously. That's just the speculation.
But it gives a very interesting signal, and this study certainly should stimulate research in humans and do some prospective studies in patients.
Dr. Carolyn Lam: Yes indeed. If I may ask, Jae-Kwan, do you have plans for further steps?
Dr. Jae-Kwan Song: Yeah, we are expecting some [inaudible 00:16:06]. The first process with proof of concept study as you know is DP4 inhibitors have been actually been used for the diabetic controls, so we may have a patient cohort who also underwent [inaudible 00:16:22] echocardiogram [inaudible 00:16:23] while without medication. The analysis of those later can be used for proof of concept study. But we are challenging issues that although many drugs are classified as a DP4 inhibitors, we should really focus on the tissue distribution on these drugs, specifically on the cardiac issues. It may be possible that the different drugs have a different tissue distribution even after all our medication. The second critical issue is what is the actual dose of these drugs to prevent calcific aortic valve disease. Usually these drugs are used for diabetes control. We may need different lab results of these drugs for different critical indications. So that's the two important issues to be solved.
Dr. Carolyn Lam: That's wonderfully put, and I couldn't agree more. Thomas, could we switch tracks a little bit. Because now that I have you online, and you're the first time joining us on the show too, tell us a little bit more about what it's like as an associate editor really looking at these pre clinical data, being able to parse out what you think has translational value, and especially for circulation. We have a very strong emphasis now on clinical translation. Share some of your thoughts there on how it's been for us.
Dr. Thomas Eschenhagen: It's been a great experience. I do have some experience with other journals as an associate editor, or being on an editorial board. But I have to say circulation is really quite unique. I think it's a very strong group of people. I'm amazed by the level of knowledge and also the level of engagement of the other editors and associate editors, in every single paper. What's also really rewarding is the overall quality of papers being submitted to circulation, it's really great. A lot of papers are not only presenting some beautiful, basic science, but also this translational perspective, that's actually what we are looking for. So very solid, exciting scientific work in cells, animals, but always some link, either some materials from humans or a good link to a translation perspective. That's the perfect paper for circulation and I have to say we get quite a bit of them, and it's sometimes even difficult to pick the ones we really like. But it's great, it's really been a lot of fun.
Dr. Carolyn Lam: This is actually one of the purposes of this podcast. It's hoping to share with our readers, with our listeners, what happens at these editor discussions because it's so interesting, I just wish everyone could listen to all the science and the clinical translation that we discuss. Thank you very much for sharing your thoughts today, both Thomas, and Jake Won, beautiful work. We're very proud to be publishing this work in circulation.
Thank you listeners for joining us this week. Don't forget, tell all your friends about this podcast, and tune in again next week.
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. In just a moment, we will be discussing the sources of sodium in the US diet, results that may surprise you, and that carry profound public health importance. But first, here's your summary of this week's issue.
The first original paper advances the field of cardiac tissue engineering by establishing a defined serum-free protocol to generate functional human myocardium from pluripotent stem cells. In this paper by first author, Dr. Tiburcy, corresponding author Dr. Zimmermann and colleagues from the University Medical Center Goettingen in Germany, the authors systematically investigated cell composition, matrix and media conditions to generate engineered human myocardium from embryonic and induced pluripotent stem cells and fiberglass, under serum-free conditions. The engineered human myocardium demonstrated important structural and functional properties of post-natal myocardium, including rod-shaped cardiomyocytes with M-bands, systolic twitch forces, a positive force-frequency response, inotropic responses to beta adrenergic stimulation, evidence of advanced molecular maturation by transcriptome profiling and the engineered human myocardium even responded to chronic cholinomimetic toxicity with contractile dysfunction, cardiomyocyte hypertrophy, cardiomyocyte death, and anti-pro BNP release, which are all classical hallmarks of heart failure.
Finally, the authors demonstrated scalability of engineered human myocardium according to anticipated clinical demands for cardiac repair. In summary, this paper provides proof of concept for a universally applicable technology for maturation and scalable production of engineered human myocardium, something that is termed a stride forward in an accompanying editorial by Doctors Yang and Murray, from University of Washington in Seattle.
The next paper describes a new frontier for interventional cardiology, the percutaneous therapy for tricuspid regurgitation. Here, Dr. Nickenig and colleagues, from University Hospital Bonn in Germany, recruited 64 consecutive patients deemed unsuitable for surgery who underwent mitroclip treatment for chronic, severe tricuspid regurgitation for compassionate use. Twenty-two patients were also concurrently treated with a mitroclip system for mitral regurgitation as a combined procedure. The degree of tricuspid regurgitation was severe or massive in 88% of patients before the procedure. The mitroclip device was successfully implanted in the tricuspid valve in 97% of cases.
After the procedure, tricuspid regurgitation was reduced by at least one grade in 91% of patients. 13% of patients with tricuspid regurgitation remained severe after the procedure. There were significant reductions in effective regurgitant orifice area, vena contracta width, and regurgitant volume. There were no intra-procedural deaths, cardiac tamponade, emergency surgeries, stroke, myocardial infarction or major vascular complications.
There were three in-hospital deaths. New York Heart Association class was significantly improved and six minute walk distance increased significantly. In summary, this study demonstrates that trans-catheter treatment of tricuspid regurgitation with the mitroclip system seems to be safe and feasible in this cohort of pre-selected patients.
The next paper describes the pooled safety analysis of evolocumab, a fully human monoclonal antibody to PSK-9. Dr. Toth of Johns Hopkins University School of Medicine and the PROFICIO investigators perform this pooled analysis from the PROFICIO program, which included over 6,000 patients from 12 Phase 2 and 3 trials, and the corresponding open-label extension trials, and they showed that treatment with evolocumab, up to one year, was not associated with discernible differences in adverse events, serious adverse events, or key laboratory assessments, compared to control or standard of care.
In addition, adverse events rates did not increase among patients attaining very low levels of LDL cholesterol, of less than 25 milligrams per deciliter, compared to patients attaining LDL cholesterol levels above 40 milligrams per deciliter. In summary, the present analysis confirms a favorable benefit risk profile for evolocumab treatment for up to one year.
Does aggressive blood pressure lowering prevent recurrent atrial fibrillation after catheter ablation? Well, this question is addressed in a randomized, open-label clinical trial known as the Substrate Modification With Aggressive Blood Pressure Control or SMAC-AF Trial. In this trial, Dr. Parkash of Halifax, Canada and colleagues, randomly assigned 184 patients with atrial fibrillation and a blood pressure of greater than 130 over 80 to aggressive blood pressure lowering, with a target of less than 120 over 80, or to standard blood pressure treatment, to a target of less 140 over 90, prior to their scheduled atrial fibrillation catheter ablation.
The primary outcome was symptomatic recurrence of atrial fibrillation, atrial tachycardia, or atrial flutter lasting greater than 30 seconds, determined 3 months beyond catheter ablation. The authors found no additional benefit to the addition of aggressive blood pressure lowering over a median of 3.5 months, over standard blood pressure therapy, in patients undergoing catheter ablation for atrial fibrillation to prevent recurring atrial arrhythmia.
In subgroup analysis, a signal of benefit was observed in groups whose blood pressure were lower at the point of entry into the study, and in those patients who were older. The duration of blood pressure lowering in the study did not result in reduction of recurrent atrial fibrillation after catheter ablation, however there was a higher rate of hypotension requiring medication adjustment in the aggressive blood pressure group.
Thus, this trial showed that neither aggressive blood pressure lowering compared to standard blood pressure lowering, nor the duration of aggressive blood pressure treatment reduced atrial arrhythmia occurrence after catheter ablation for atrial fibrillation, but resulted in more hypotension.
Well, that wraps it up for our summaries! Now, for our feature discussion ...
Our topic today is so universal and so important. It's about sodium intake and the sources of sodium, at least in the US, and I have with me two lovely ladies, the corresponding author of our paper, Dr. Lisa Harnack, from School of Public Health, University of Minnesota, and a regular on the show, shall I say, Dr. Wendy Post, Associate Editor from Johns Hopkins. Welcome, ladies!
Dr. Wendy Post: Thanks you, Carolyn! It's a pleasure to be here.
Dr. Lisa Harnack: Thanks, thanks.
Dr. Carolyn Lam: Lisa, let's dig right into your paper. Let's start by discussing that there was a prior paper that looked at sources of sodium in the US population. So please tell us, what inspired you to do your paper, and were you surprised by your findings?
Dr. Lisa Harnack: Right, well the previous study was over 25 years old, and it involved just 69 people from one geographic area, and, you know, it was informative, but it didn't tell us about America today, and how much sodium we're getting from different sources, and it didn't tell us much about a variety of ethnic groups ... we're a diverse country. So the CDC actually funded this study, and really they saw the need for it and laid out that this study needed to be done, as it was done, in three geographic areas, representing different ethnic groups.
Dr. Carolyn Lam: Tell us what you did.
Dr. Lisa Harnack: So, we recruited 450 people from 3 different areas, from Minneapolis/St. Paul metropolitan area ... Stanford was a partner in this study and they recruited people from that area of California, and then, finally, Birmingham, Alabama was a partner was a partner, and we got participants from there.
So the racial groups we had represented were white Americans, African Americans, Asian Americans and Hispanics.
Dr. Carolyn Lam: Yeah, I was really struck ... you had almost equal representation of women as well, didn't you?
Dr. Lisa Harnack: Right, so we made sure we had half of the participants were women, so we could really see how things stood with a variety of groups.
Dr. Carolyn Lam: That's excellent. What I was really impressed, as I'm sure, Wendy, you were, too, was the detail of the methodology. Could you tell us a little bit about that?
Dr. Wendy Post: Right, so we wanted to know all the sources of sodium. Part studies have tended to not ask about salt added to food at the table, and in home food preparation, because it's really hard to actually know ... you know, if you ask somebody, "Oh, did you add salt at the table? How much did you add?" They don't know. They just say, "Oh, well, I shook some salt on." So, we had people collect duplicate samples of the salt they added to food at the table and home food preparation. We gave them little baggies ... collection bags ... you know, after they added salt at the table, shake some into the baggy. So, we knew exactly how much because people do add salt in the home, so they have some control over how much sodium is in their diet. But the question is in how much under people's control in their home versus what's coming from the food supply.
Dr. Carolyn Lam: Right. And what I loved about the results is ... I think that it would challenge a lot of what people expect. Because when we talk about sodium restriction, everyone thinks, "Oh, it's the additional salt we add." And your study actually had surprising results. So, could you tell us?
Dr. Wendy Post: Yes, so it really was clear that the salt that people add at the table is just 5% of their total sodium intake, on average, across people in our study, and the salt added in home food preparation, like maybe the salt you add to your pasta when you're boiling it or to your eggs ... that was just 6%. So, 11% of the sodium in our study participants' diets was sort of that under-your-control in-the-home, and the rest was from other sources. So, the other things we looked at was, "Will water contribute some sodium?" So, we wanted to see how much comes from your home tap water. There's sodium that's just naturally occurring in food, like milk just naturally contains some sodium. So we wanted to look and see how much came from just naturally occurring in the food, and then the other question was how much is added by food manufacturers as part of making the food product, and that included the salt that might be added in making potato chips, as well as in restaurants ... the salt that might be added in making French fries or a pasta dish at a restaurant.
Dr. Carolyn Lam: And the biggest culprit?
Dr. Lisa Harnack: Yes, the biggest culprit was that latter source ... food added in processing.
Dr. Carolyn Lam: I thought that was amazing. Wendy, what do you think the public health message is? I mean, 70% almost of the salt's coming from processed foods from outside. What do we do? Stop eating it? What do we do?
Dr. Wendy Post: Right, so, on the editorial board for Circulation, we really liked this paper because of its very high impact for a public health message. So, as was stated, the sodium that we're getting in our diet is largely coming from processed foods and from foods we eat in a restaurant. So there are a number of ways that that can be modified and one is for our patients to read food labels and to make smart choices when they are shopping for processed foods in the supermarket.
But the other is for food manufacturers to decrease the amount of sodium in the products that they are making and there are voluntary suggestions by the FDA that food manufacturers reduce the sodium content of the food, and especially bread is incredibly high in sodium, and I suspect that most of our patients don't know that. So, if we were able to reduce the amount of sodium in the food supply by just a small fraction, it could have a large public health impact because we all eat.
So, it would affect everybody, and then I think the other really important public health message is about eating in restaurants and, of course, some people eat out more than others, and some people eat out in fast food restaurants, which, of course, are very high in sodium, but even in some of the nice restaurants that we go to, even expensive restaurants, the food is very heavily salted and I, for one, when I go out to eat, and sometimes don't like the taste of the food because it has so much salt in it, when I'm used to eating a low sodium diet.
So, there are a number of changes that occur on that level. One is for our patients to understand what foods tend to have a lot of sodium at a restaurant, but also for restaurants to notify their clientele of what foods are potentially lower in sodium and calories and generally provide the nutrient value so that we can make smart choices when we eat out.
Dr. Carolyn Lam: Yeah, indeed, congratulations, Lisa - what an important paper. Quick question, so that was the overall main message, but did you find any differences by different racial groups, by sex, by different socioeconomic status?
Dr. Lisa Harnack: We did find some differences. We found one difference was it looked like African Americans tend to add more salt at the table than some of the other groups, and, actually, Asians add less in our study. But still for all groups, that sodium added to food in processing was still the main source by a long shot, so, although there were some small differences by groups, it was clear that for all groups, the issue was the sodium added in processing.
Dr. Carolyn Lam: And for both Lisa and for Wendy, do you think these results are generalizable even beyond the US?
Dr. Wendy Post: I'd imagine that there would be quite a lot of variability, based on the habits of the various populations. So, here we're talking about eating outside the home, or food that's processed outside of the home, so there may be countries where most people are producing their own food and not necessarily buying processed foods or eating in restaurants, and then this would definitely be less applicable. And, of course, there are differences in foods that we eat based on our different ethnic groups.
Dr. Lisa Harnack: No, I would agree with what's just said. It really could be variable, but it does seem that a lot of countries are concerned about processed foods. Some countries implemented mandatory limits on the sodium in the foods in their food supply, so that would indicate to me that they know there's ... for some countries, there's serious concern about this source of sodium.
Dr. Carolyn Lam: Yeah, and I think this is really a wake-up message for us to examine where these sources of sodium ... I mean, even that simple message that it could be coming from bread, from drinking water, I think that would be surprising to a lot of us, even those of us practicing in medicine. Wendy, finally, you thought this was important enough to invite an editorial. I'd really like your thoughts there.
Dr. Wendy Post: You'll be able to read the editorial when it comes out in print, but the editorial also congratulates the authors on a really important paper, and the important public health messages, and, especially, compliments the authors on having a diverse group of participants, including ethnic minorities and men and women, and different geographic locations, so overall, it's a very important paper that I'm sure will have an important impact on the public health of our country and others.
Dr. Carolyn Lam: Listeners, you heard it right here. Remember, you're listening to Circulation on the Run. Please share this episode, and tune again next week!
Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Doctor Carolyn Lam, associate editor for the National Heart Center and Duke National University of Singapore. Our feature paper today presents the first information on the impact of cardiovascular health in middle age and the burden of mobility in older age. This exciting data is from the Chicago Heart Association study. First, let me give you your summary of this week's journal.
The first study tells us that patients with long QT syndrome type II are at increased risk of hypoglycemia. First author, Doctor Hilton Cavallius, co-corresponding authors Doctor Tarakov and Hanson from University of Copenhagen, Denmark, noticed that loss of function mutations in HERG, which encodes the voltage gate at potassium channel 11.1, causes long QT syndrome II, but that the specific voltage gate at potassium channels are also present in pancreatic alpha and beta cells and intestinal L and K cells, which secrete glucagon, insulin, and the incretins, glucagon-like peptide one or GLP1, and glucose-dependent insulinotropic polypeptide, or GIP.
All these hormones are crucial for glucose regulation. The authors therefore hypothesize that patients with long QT syndrome II may have increased incretin and beta cell, but decreased alpha cell function and thus, lower glucose levels. To test this hypothesis, they measured secretion of these hormones and cardiac repolarization in response to a six-hour, 75 gram oral glucose tolerance test in 11 patients with long QT syndrome II with functional mutations in HERG with 22 matched healthy participants.
They found that following glucose ingestion, patients with long QT syndrome II displayed exaggerated incretin and endocrine pancreatic function with more than 50% increased levelsq of circulating insulin, GLP1 , and GIP and defective glucagon secretion, causing low plasma glucose levels and thus, increased risk of symptomatic reactive hypoglycemia following the glucose load.
Furthermore, in rats, pharmacological blockade of these voltage gate at potassium channel 11.1 with [inaudible 00:02:43] had similar effects and inhibition of HERG in beta and L cells increased insulin and GLP1 secretion up to 50%. Finally, glucose ingestion aggravated cardiac repolarization disturbances in patients with long QT syndrome II with a 122% greater increase in QT interval in these patients compared to controls. The take home message is that clinicians should be more aware of the risk of hypoglycemia with glucose ingestion in patients with long QT II syndrome and also recognize that this reactive hypoglycemia can further increase the risk of malignant arrhythmia in these patients.
The next paper is the first study to describe the risk of myocardial infarction after discontinuation of thienopyridine therapy in the DAPT study, or dual antiplatelet therapy study. As a reminder, in this trial, after PCI and 12 months of clopidogrel or prasugrel plus aspirin, eligible patients remained on aspirin and were randomized to continue thienopyridine versus placebo for 18 months. At 30 months, patients stopped the study drug and were observed for three months. In the current study by first author Doctor Schmidt, corresponding author Doctor Mauri, and colleagues from Brigham and Women's Hospital in Boston, Massachusetts. The authors looked at cumulative incidents of myocardial infarction assessed over three months after randomization and three months after study drug discontinuation. They found that discontinuing thienopyridine after either 12 or 30 months was associated with an early increase in myocardial infarction risk, mainly unrelated though to stent thrombosis. The magnitude of risk was highest in the early time frame and lower in patients not treated with the [inaudible 00:04:47] eluting stents.
The authors further compared pateints with DAPT scores above or below 2, and showed that both groups had lower rates of myocardial infarction with continued thienopyridine . Thus, while higher DAPT scores identify patients with a greater absolute ischemic benefit relative to bleeding with continued thienopyridine therapy, discontinuation at 12 months increases the myocardial infarction hazard regardless of DAPT score group.
The next paper describes the impact of depression treatment on one year mortality following acute myocardial infarction. Doctor [inaudible 00:05:28] and colleagues from the University of Missouri School of Medicine in Kansas City looked at the TRIUMPH study, which is an observational multicenter cohort study that enrolled more than 4000 patients with acute myocardial infarction between 2005 and 2008 from 24 US hospitals.
Patients were administered the patient health questionnaire 9 during the index myocardial infarction admission and depression was defined by a score of 10 or above. This was categorized as treated if there was a documentation of a discharged diagnosis, medication prescribed for depression, or referral for counseling, and is untreated if none of these three criteria were documented. Overall, 18.7% of patients met criteria for depression and 30.4% were treated. Compared without depression, patients with treated depression had one year mortality rates that were not different. However, patients with untreated depression had a higher one year mortality when compared to patients without depression. In summary, this study really shows that the association between depression following myocardial infarction and increased mortality differs by depression treatment status at the time of the index myocardial infarction. Patients with untreated depression have a 70 to 90% higher risk of dying at one year after the myocardial infarction than patients without depression or patients with treated depression. These findings should therefore encourage further research to examine the impact of depression recognition and treatment at the time of an acute myocardial infarction.
The final study provides insight into the paradox that folate deficiency is an independent risk factor for congenital heart disease, yet the maternal plasma folate level is paradoxically not a good diagnostic marker of this risk. In the current study by first author Doctor Wang, co corresponding authors Doctors Chow and Wang, from Fudan University, Shanghai, China. The authors examined six folate related polymorphisms in three independent case control groups comprising 1489 patients with congenital heart disease and 1745 healthy individuals from the Han Chinese population. They found that a specific fidgetin intronic 4 variant was associated with decreased circulating folate levels and increased protection against congenital heart disease. They further showed that increased fidgetin expression inhibited proteasomal degradation of reduced folate carrier 1 and dihydrofolate reductase, thus facilitating [inaudible 00:08:29] uptake and metabolism of folate. Their results therefore demonstrated that folate utilization, rather than the circulating folate levels, determined the preventive effects of folate against congenital heart disease. These findings provide new insights into the relationship of circulating folate levels with congenital heart disease and potentially other folate associated diseases.
Well, that wraps it up for your summaries. Now, for our feature discussion.
Today's feature paper really represents the first data we have that tells us what our cardiovascular health in middle age is doing to us in older age, in terms of both morbidity and longevity. To discuss this paper today, I'm so happy to have the first and corresponding author, Doctor Norrina Allen from Northwestern University in Chicago and Doctor Jarett Berry, associate editor from UT Southwestern. Welcome, both.
Dr Norrina Allen: Thank you very much.
Dr Jarett Berry: Thanks, Carolyn.
Dr Carolyn Lam: Norrina, could I start with you? This represents the 40 year follow up of the Chicago Heart Association detection project and industry. Could you maybe start by telling us a little bit about the Chicago Heart Association study?
Dr Norrina Allen: The Chicago Heart Association study was a large study that recruited almost 40,000 individuals who were employed in Chicago. They did a baseline exam between 1967 and 1973. After that baseline exam, we followed those individuals for over 40 years using their Medicare records, so we've been able to monitor their healthcare utilization and the incidence of disease across their lifetime up through 2010.
Dr Carolyn Lam: Then you measured their cardiovascular health by specific measurements, right? Could you tell us how that was defined and then also how was morbidity burden defined?
Dr Norrina Allen: Of course. We really think the overall burden of cardiovascular health tells us something more than looking at individual risk factors, so we classified each of the CHA participants into one of four groups, and each of those groups was defined by the level of main cardiovascular risk factors, including blood pressure, BMI, diabetes, smoking, and cholesterol level. We identified people who had favorable levels of all of those risk factors, individuals who had one elevated but not clinically of those high risk factors, individuals who had one high level, or individuals who had two or more high levels. That was based on their baseline exam. Overall we found that about 6% of the CHA participants had favorable levels of all of the risk factors at baseline, 19% had one or more that was elevated, 40% had one high, and 35% had two or more high risk factors, and again this was at the baseline exam when they were young to middle aged.
We then followed them, as I mentioned, using Medicare data and we identified the burden of whole morbidity based on the ICD9 codes in their Medicare record, and we identified the level of morbidity for each year of age, from entry into Medicare, [inaudible 00:11:54] all the way to their death.
Dr Carolyn Lam: And now, drum roll, your findings, they were pretty stunning.
Dr Norrina Allen: Yeah. As you mentioned when you introduced the study, this study is really the first to look at the whole of an individual's later life, meaning not just looking at the incidence of disease or longevity but taking those both into account. What we were particularly interested in was looking at the cumulative burden of morbidity in older age and the relative proportion of life that people live with cardiovascular or all cause morbidity. What we found was that individuals, who at baseline in young and middle age and favorable levels of all major cardiovascular risk factors, lived longer by almost four years but they also delayed the onset of all cause and cardiovascular morbidity by 4 and a half and almost 7 years respectively. What that means is that the proportion of their life that they live with morbidity was much shorter, they lived longer and healthier as compared to individuals who had one or two more high risk factors.
Dr Carolyn Lam: What an important public health message. Jarett, this concept of morbidity compression, tell us your thoughts.
Dr Jarett Berry: This is a really important paper. We've known for a long time, of course, that low risk individuals live longer, but the question of whether or not low risk individuals lived better throughout their life has been incompletely understood. The problem is that because low risk individuals live longer, the question that many have asked is that when we live longer is there a so-called expansion of misery, which some have talked about? That we live longer, but we have the same burden of disease or is that extended time horizon with the extended life span ... is the burden of morbidity compressed into a shorter period of time? In order to do that you need a couple things. You need a very large study that's followed for a very long time. Importantly, not just follow them for a long period of time, but follow enough individuals all the way until death so you know not just the first part of the story but we know the end of the story.
It really wasn't until [inaudible 00:15:18] paper, with not only the very large sample side but the very long term follow up until death, that we've been able to understand that actually low risk status in middle age does actually compress morbidity. This question of morbidity compression is not just an academic question but it actually has potential implications for cost savings and how we think about health care costs in our health care system. It'd be nice to hear [inaudible 00:15:18] thoughts about that as well, what else she found in regard to the Medicare costs.
Dr Norrina Allen: Right. As Jarett mentioned, not only from an individual perspective but at a societal level, what we're interested in is whether being in favorable cardiovascular health actually lowers healthcare costs at the same time as increasing an individual's health and longevity. What we found was that not only do the individuals in favorable health live longer and healthier, but they also have lower cumulative and annual healthcare costs, meaning that from a societal standpoint the compression of morbidity results in healthcare savings. We really think this is a strong method that provides support for earlier prevention efforts not only to improve an individual's quality of life but to reduce the healthcare costs associated with later life morbidity.
Dr Carolyn Lam: Indeed, what an important message to live longer and better and to save societal cost we need to get healthier cardiovascularly in middle age. Now, what really scares me though, is the statistic you told us a bit earlier. Only 6% of the individuals that you studied had a favorable level of all factors. What do you think this implies? What do you think needs to be done?
Dr Norrina Allen: Unfortunately, at this point, it's relatively rare in our population to reach middle age, 40 to 50 years of age, with favorable levels of all major cardiovascular risk factors. I think ... my research is really focused on trying to identify ways and times to intervene, to really help promote cardiovascular health early in life. I really think that we need to work hard to prevent the occurrence of these risk factors and the elevation of these risk factors much earlier in life. That means, even before the age of 40 and much earlier than that, we really need to be focusing on preserving cardiovascular health so that by the time individuals reach later life they can have a good quality of life and a longer, healthier life.
Dr Jarett Berry: I think the issue of the fact that low risk status is rare is that's a challenge that we continue to wrestle with as a society and as investagators interested in this are and how to improve that. When you look at your data, Norrina, I guess one silver lining here is we do see that ... when you look across the strata of risk groups ... it wasn't just the low risk individuals that seemed to benefit. It seemed that there was a little bit of a dose response. The goal obviously is to promote low risk status, but if we could limit the prevalence of those at the highest risk and shift them down a little bit, that could also have potential implications. I'd be interested to hear your thoughts about that.
Dr Norrina Allen: I think that's very accurate. There really is kind of a dose response level, so that every risk factor that's favorable adds a benefit and the more we can do to reduce the high risk factors over time, the better the long term outcomes are likely to be. I do really think prevention doesn't only have to exist before the development of the risk factors, but also there's a benefit to reducing risk factors that may have already developed or are elevated, and to try and reduce their level. I would say that I think that's an interesting next step that we really want to look at and try and think about how best to intervene even at middle age and help improve outcomes much later in life.
Dr Carolyn Lam: Thank you, listeners, for joining us today. I'm sure you agree, it's such an important message. Share it with your friends and tune in next week.
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. Our feature paper this week really adds to our understanding of the cause/effect relationship between obesity and heart failure, this time by comparing the effects of gastric bypass surgery versus intensive lifetime treatment on heart failure risk. Before we talk about that, though, let me give you your summary of this week's journal.
The first paper brings us one step closer to understanding cardiac recovery in response to mechanical unloading by left ventricular assist devices and it does this by showing that this process may involve the transverse tubular system, which is a micro structural feature of ventricular cardiomyocytes important for contractility and consisting of tubular invaginations of the sarcolemma predominantly located at the Z-lines of sarcomeres. This transverse tubular system is crucial for efficient excitation contraction coupling by bringing L-type calcium channels in the sarcolemma in proximity to clusters of ryanodine receptors in the sarcoplasmic reticulum.
In the current study by co-corresponding authors, Dr. Seidel and Drakos and Sachse from University of Utah, the authors studied left ventricular biopsies obtained from five donors and 26 patients with chronic heart failure undergoing implantation of left ventricular assist devices or LVAD's. They used three dimensional confocal microscopy and computational image analysis to assess the transverse tubular system's structure, density, and distance of ryanodine receptor clusters to the sarcolemma.
They found that the majority of heart failure myocytes showed remarkable transverse tubular system remodeling, particular sheet-like invaginations of the sarcolemma, which is previously unknown phenotype. This sheet-like transverse tubular system remodeling led to increased distances of ryanodine receptors to the sarcolemma causing heterogeneous intracellular calcium release and consequently inefficient excitation contraction coupling. High degrees of transverse tubular remodeling at the time of LVAD implantation was associated with absence of functional cardiac recovery during mechanical unloading, whereas preserved transverse tubular systems structure was associated with recovery.
In summary, cardiac recovery during unloading may require an intact transverse tubular system at the time of LVAD implantation. And characterizing this system may help to identify patients with a high probability of functional cardiac recovery in response to mechanical unloading.
There have been a proliferation of algorithms based in high sensitivity assays for cardiac troponins for the diagnosis or exclusion of myocardial infarction. All these algorithms have the potential to overwhelm clinicians with options. Well, there is help in this week's issue with two observational studies directly comparing the diagnostic performances of multiple high-sensitivity troponin testing strategies.
Now, before I describe these two studies in detail, here are some important reminders. Remember that as of early 2017, although high-sensitivity troponin assays are routinely used in many regions of the world, they are not available in the United States. Thus, the specific algorithms discussed here are not applicable with the contemporary sensitive assays that are presently used in the United States. Next, let's remind ourselves that both the United States and European professional guidelines recommend serial measurement of cardiac troponins at presentation or zero hours and three to six hours later with additional testing beyond six hours in patients who have electrocardiographic changes, or intermediate or high clinical risk features.
The 2015 European Society of Cardiology Guidelines also included an alternative strategy reducing the sampling interval to one hour when using a high sensitivity troponin assay with a validated zero and one hour algorithm based on the 99 percentile cutoff of these high sensitivity troponin assays. Now to the two studies in the current issue, which tie together the expanding evidence with direct comparisons of several of the strategies using the same high sensitivity cardiac troponin assay by Abbott.
Dr. Chapman and colleagues from the royal infirmary of Edinburgh, United Kingdom, compared the standard ECS zero and three hour strategy based on the 99th percentile upper reference limit at both time points with the high sensitivity troponin in the evaluation of patients with acute coronary syndrome, or high stakes algorithm, and that would be a zero, three, and six hour algorithm that incorporates a zero hour criteria and at a very low cutoff of five nanogram per liter and a three hour criterion that directs patients with either a rising concentration or with an absolute concentration above the upper reference limit to additional testing.
Among 1,218 patients with suspected myocardial infarction, the high stakes algorithm delivered both a higher proportion ruled out for myocardial infarction at zero hours and a higher negative predictive value of 99.5% versus 97.9%. The ESC pathway missed 18 index and two recurrent myocardial infarction events, whereas the high stakes pathway missed two index and two recurrent myocardial infarction events. These findings demonstrate the value of adding a very low zero hour cutoff to facilitate earlier rule out as well as the value of a delta criterion to exclude increasing values among patients that progress to three hour sampling.
In the next study, first author, Dr. Boeddinghaus, corresponding author Dr. Mueller and colleagues from University Hospital of Basel, Switzerland compared the ESC alternative zero and one hour strategy with three other approaches using either a single cutoff at zero hours, or the one hour strategy. Among 2,828 patients with symptoms suspicious for myocardial infarction and no ST elevation, each of these four approaches delivered a negative predicted value above 99% comparing favorably to the ESC zero and three hour algorithm that had a negative predictive value of 98.4%.
Now, although each of the strategies performed similarly among patients presenting more than two hours after symptom onset, among the early presenters, the negative predictive value and sensitivity were diminished using the single zero hour cutoff of five nanograms per liter. The authors concluded that the single cutoff strategy, the one hour algorithm, and the zero and one hour algorithm, allow the triage towards rule out of myocardial infarction in more than half of consecutive patients presenting with suspected MI to the emergency department. However, the single cutoff strategy should not be used in patients presenting early after chest pain onset.
These papers are discussed in an excellent editorial, which also puts everything in perspective by Dr. David Morrow from Brigham and Women’s Hospital in Boston, Massachusetts. I particularity want to refer all of you to the figure that's found in its editorial which really helps you to understand the different strategies involved.
The final study tells us about potential death averted and serious adverse events occurred from the adoption of the SPRINT intensive blood pressure regimen in the United States. As a reminder, the systolic blood pressure intervention trial, or SPRINT demonstrated a 27% reduction in all caused mortality with a systolic blood pressure goal of less than 120 versus less than 140 mm Hg among American adults at high cardiovascular risk, but without diabetes, stroke, or heart failure.
In the current study, Dr. Bress and colleagues from the University of Utah School of Medicine applied the SPRINT eligibility criteria to the 1999 to 2006 National Health and Nutrition Examination Survey or NHANES and linked this with the national death index through December, 2011. They found that if fully implemented in eligible US adults, intensive blood pressure treatment was projected to prevent about 107,500 deaths and 46,100 of heart failure per year. But, you also give rise to about 56,100 episodes of hypertension. 34,400 episodes of syncope, 43,400 serious electrolyte disorders, and 88,700 of acute kidney injury per year compared to standard blood pressure treatment. Thus, they take home message is careful patients selection and implementation are important because intensive treatment while preventing deaths is associated with increased risks of hypertension, syncope, electrolyte abnormalities and acute kidney injury.
Well, that brings us to a close for the summaries, now for our feature discussion.
We are discussing obesity and heart failure. Now, we've heard of the obesity paradox, but we also know that obesity may be a risk factor for heart failure and the study today really puts perspective on this and is really one of the largest most convincing studies I've read on this topic. I am so pleased to have the person corresponding author, Dr. Johan Sundstrom from Uppsala University Hospital in Sweden. Welcome, Johan.
Dr Johan Sundstrom: Thank you, lovely to talk to you.
Dr Carolyn Lam: And especially pleased to have back on the show again, Dr. Torbjorn Omland from University of Oslo, Norway. Hi, welcome back, Torbjorn.
Dr Torbjorn Omland: Thank you very much. It's a great pleasure being here.
Dr Carolyn Lam: Johan, you know what? Could you just start by telling us about your study?
Dr Johan Sundstrom: So, we were fortunate enough to have two great databases here in Sweden. One was the obesity surgery registry called SOREG in which all people have a gastric bypass surgery, for people who are registered. And we also have a company called Itrim who provide intensive lifestyle program, which takes people down on average about 11 kilos, and they have a very structured database as well. So, we were able to pull this data in order to try and understand the effects of intentional weight loss to two different levels of weight loss, what that does to the heart failure incidence.
This is a bit of a comparative effectiveness study, so it's of course necessary to make the examples as similar as possible to apply exclusion criteria. We took away everyone who had a body mass index of less than 30 and above 50 and then we applied propensity scores to those two data sets and we had to trim the data sets a little bit further in order to get so called region of common support, which means that we were left with two samples who could have either had surgery or a lifestyle intervention. And then we applied an inverse probability weighting scheme to that. It's statistically complicated but what that does, is it's a matching, but it's not as complicated as matching. With matching, you just give people a weight of 1 or 0, but this gives people other weights as well.
So, we end up with characteristics that were very similar at baseline. So, we tried to mimic as close as possible what a randomized clinical trial looks like, but of course we did it posthoc and it’s observational. So, we get our table one, sort of, in this paper that shows very similar characteristics of the two groups. So, what we did then is we noted what happened to the people in these two groups in terms of heart failure incidence and we followed them in our national inpatient registry. So, all the Swedish citizens get a personal identification number so we can use that to follow people in our patient registry. So, we know exactly what drugs people will collect from pharmacies, and we know what they died from, and we know all of their hospitalizations. And we previously validated their heart failure diagnosis in the Swedish Inpatient Registry and we noted that you were in a pretty good position if you were hospitalized with heart failure as the main cause of hospitalization and we noted that people who had agreed to do surgery, had about half the incidence of heart failure than people who were in the intensive lifestyle program.
We also noted, if you looked at the achieved weight loss one year after baseline, we noted that a ten kilo weight loss after one year was related to about a 23% lower risk of heart failure. So we noted a litany of association between the achieved weight loss and heart failure incidence. It should said, though, that heart failure in this age group, they are only 41 on average, 41 years old. Heart failure's still very unusual at this age, even in many of these people. We only had 73 cases of heart failure. So, the exact numbers need to be taken with a pinch of salt and have wide confidence intervals around them.
Dr Carolyn Lam: Johan, this is exactly why I'm so impressed with your data. First you showed a dose response relationship between the weight loss and risk of heart failure. You also show that it's not an event that occurs very often and so, it would be very difficult to imagine doing a randomized controlled trial for example in this setting and having to wait very long for these events. So, it really goes to show your observational data are extremely important. And I really like the way you took the pains to describe how you tried to overcome the differences that exist between the groups and try to make it as much resembling a randomized trial setting as you could. So, maybe I could turn it over to you, Torbjorn. Could you tell us what you think the implications of this paper are?
Dr Torbjorn Omland: First, I will say that that this paper has all the characteristics of a very high quality study. It's a very timely topic that interests a lot of people. The paper's very well written. It's a large sample size as you said and it was very clinically meaningful difference between the groups and that translated into very clear and robust answers. So, I think that this has every mark of high quality paper.
But, of course, the very important question is how will this translate into actions? How can we use this information to prevent problems? We know heart failure is a very prevalent disease, especially in the elderly and although the incidence was lower here, I think my question for Johan at least is what would be the next step? What changes can we implement to reduce heart failure among the obese?
Dr Johan Sundstrom: That's a great question. I think in this study puts a little piece of the puzzle on the table and that's trying to add a little more evidence towards a causal association between obesity and heart failure. I'm not sure about what we can offer these patients and what will be the translation to lower heart failure incidence in the long run. Of course, we need to follow this sample for longer to have more heart failure cases, because I don't think we've seen the full impact of weight loss in these two samples. We might need to follow them into older age where they would have a higher heart failure incidence.
But, how to tackle obesity, I think we'll need accommodate population strategies and high risk strategies. I think if the general consensus in the scientific community after reading this and other important papers, is that there's causal link between obesity and heart failure, then we might need to understand that people who are obese and who have shortness of breath and perhaps swelling or what not, may not just be having low fitness, they might actually behaving signs of heart failure.
So, I think as a sort of increased diligence on heart failure, these people might be one thing. But, we didn't really study that. So, I wouldn't draw conclusion. But, otherwise I think it's more of a causal inference piece of the puzzle that we've laid rather than a clinical care piece of the puzzle.
Dr Torbjorn Omland: No, I agree, and here you won't to make any recommendations in regards to what interventions you should recommend particularly based on this particular study.
Dr Johan Sundstrom: No, because I think there are so many other things that need to be taken into account when it comes to treatment of obesity. Heart failure is actually one of the uncommon outcomes in this age group. We're looking at other outcomes after they present. Myocardial infarction, ventral fibrillation and mortality are actually much more common. So, I think a lot of other data should go into decisions on how to treat patients, not just for heart failure, which is still fairly uncommon at this age.
Dr Carolyn Lam: Going back to the other question that Torbjorn asked, do you think that this question still needs to be answered in any way? You've got the Mendelian randomization data. Now, you've got your data. Do you think it's still a question of whether obesity is a risk factor for heart failure? And just in case there's any confusion out there, would you put that together with the so called obesity paradox in heart failure?
Dr Johan Sundstrom: To answer the first one, I think we're not going to have any randomized evidence. Treatment of heart failure with intensive programs and prevention of heart failure ... It needs for huge samples that I don't think we're going to have any much better observational evidence anytime soon either. So, we can probably set that question aside a little bit. But, when it comes to the obesity paradox, first of all that's not what we studied here. We didn't have anyone with heart failure in this sample. We included all those people. We can only speculate. I'm a clinical epidemiologist myself, but I'm envious of people who have animal and other models because I think there's a lot more work to do in terms of ppars and and lipid metabolism in obesity and in heart failure. So, I think there'll be more interesting experimental research to come that can help us answer the obesity paradox.
Dr Carolyn Lam: Please don't forget to tell your friends about this podcast, and tune in again next week.
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. Our feature paper this week discusses the very important patient group with myocardial infarction and non-obstructive coronary artery disease, a paper that we will be digging deep into right after these summaries.
The first paper identifies a novel therapeutic target in pulmonary arterial hypertension, and that is nicotinamide phosphoribosyltransferase, a cytozyme which regulates intracellular NAD levels and cellular redox state, regulates histone deacetylases, promotes cell proliferation, and inhibits apoptosis.
This is a paper from first author Dr. Chen and co-corresponding authors Dr. Machado from University of Illinois Chicago and Dr. Garcia from the University of Arizona. The authors found that plasma and mRNA and protein levels of nicotinamide phosphoribosyltransferase were all increased in the lungs and the isolated pulmonary arterial endothelial cells from patients with pulmonary arterial hypertension.
They were also increased in the lungs of rodent models of pulmonary hypertension. Nicotinamide phosphoribosyltransferase deficient mice were protected from hypoxia mediated pulmonary hypertension; whereas, enhanced activity promoted human arterial smooth muscle cell proliferation via paracrine effect and inhibition of activity attenuated pulmonary hypertension in rats.
This paper, therefore, provides evidence that nicotinamide phosphoribosyltransferase plays a role in pulmonary vascular remodeling and its inhibition could be a potential therapeutic target for pulmonary arterial hypertension.
The next study suggests that high sensitivity cardiac troponin T may be an early biochemical signature for clinical and subclinical heart failure. In this study from first author Dr. Seliger, corresponding author Dr. deFilippi, and colleagues from Inova Heart and Vascular Institute, the authors measured high sensitivity cardiac troponin T at baseline among almost five thousand participants in the multi-ethnic study of atherosclerosis MESA cohort, who were initially free of overt cardiovascular disease.
Cardiac magnetic resonance imaging was performed at baseline and repeated 10 years later among 2,831 participants who remain free of interim cardiovascular disease events, among whom 1,723 also received gadolinium enhanced cardiac magnetic resonance for characterization of replacement fibrosis by late gadolinium enhancement. Results showed that a mild elevation of high sensitivity cardiac troponin T identified subjects at highest risk for an increase in left ventricular mass and end diastolic volume over the next 10 years.
Higher levels also associated with an increased incidence of replacement fibrosis, but with no differentiation between ischemic or non-ischemic fibrosis patterns. For the more high levels remained an independent predictor for incident heart failure, coronary heart disease events and cardiovascular events, independent of underlying left ventricular hypertrophy or ejection faction.
The implications are that myocyte injury, measured with a highly sensitive cardiac specific troponin assay may ultimately be an important early signal used to target therapy to prevent or delay left ventricular remodeling and progression to heart failure.
Does maintenance of cardiovascular risk factors at target eliminate the excess risk of mortality in cardiovascular diseases associated with type 1 diabetes? Well, this question was addressed in the next paper by Dr. Rawshani and colleagues of the Swedish National Diabetes Register in Gothenburg Sweden. The authors compared more than 33,300 patients with type 1 diabetes to more than 166,500 match controls without diabetes from the Swedish National Diabetes Register. They found that patients with type 1 diabetes, with five selected cardiovascular risk factors at target, demonstrated a non-significant access risk of death compared to controls.
These five risk factors included glycated hemoglobin, blood pressure, albuminuria, smoking, and LDL cholesterol. Nonetheless, despite having all risk factors at target, persons with type 1 diabetes still had 82% to 97% elevated risk of myocardial infarction and heart failure respectively. For every incremental risk factor not at target, the excess risk of death in cardiovascular outcomes increased in a graded fashion.
In conclusion, there was a steep graded association between decreasing number of cardiovascular risk factors at target and major adverse cardiovascular outcomes with patients with type 1 diabetes. While achievement of current evidence based target levels of five cardiovascular risk factors markedly reduced or even potentially eliminated the excess mortality risk, these patients remained at higher risk of myocardial infarction and heart failure compared with controls.
The final paper suggests that hemodynamic guided heart failure management may be beneficial in general clinical practice and not just in the context of controlled trials. In this study by Dr. Heywood and colleagues from Scripps Clinic Torrey Pines in La Jolla, California, the authors examined the first 2,000 patients implanted with the novel Pulmonary Artery Pressure Sensor, CardioMEMS, in the general cardiology practice setting.
They found that patients uploaded information an average of every 1.2 days, and that pressures were significantly reduced by remote monitoring using the Pulmonary Artery Sensor where patients with the highest mean pulmonary artery pressures had the highest reduction in pressures. Furthermore, they found that these general use patients experienced a greater reduction in pulmonary artery pressure over time compared to those in the pivotal CHAMPION clinical trial.
The results from this large observational study, therefore, demonstrates hemodynamic heart failure management may be effective in U.S. clinical practice with high rates of patient adherence and effective pressure management.
This paper is accompanied by an excellent editorial by Drs. Gorter, Rienstra, and van Veldhuisen from University Medical Center, Groningen, Netherlands, which really places this paper in the clinical context of heart failure and particularly patients with heart failure and preserved ejection faction
Well that wraps it up for your summaries. Now for our feature discussion.
We're discussing a hugely important emerging issue today. And it's MINOCA, a myocardial infarction with non-obstructive coronary arteries, and a very important paper in today's issue, which really provides the first insight into potential long-term medical therapy in the management of MINOCA.
However, now this issue of MINOCA is quite new and I'm sure new to many of those listening on the line. So, I am with the first and corresponding author of the paper, Dr. Bertil Lindahl from Uppsala Clinical Research Center in Sweden. Welcome.
Dr Bertil Lindahl: Thank You.
Dr Carolyn Lam: And also the associate editor who managed this paper, Dr. Gabriel Steg from Hospital Bichat in Paris, France. Welcome back.
Dr Gabriel Steg: Hello.
Dr Carolyn Lam: Now, we need to start by first understanding what we're talking about. MINOCA ... give us a good definition of what you mean by MINOCA. And does it include the non-coronary causes of AMI, or non-obstructive disease? Does it include myocarditis? Does it include the non-cardiac causes, like pulmonary embolism?
Dr Bertil Lindahl: Our definition of MINOCA used in this paper is that you received the ICD code for acute myocardial infarction. If you have a clinically clear case of myocarditis or Takotsubo and were not included in this analysis. But we know if we look into patients that have got the diagnosis of myocardial infarction ... if you performed, for instance, MRI afterward, you can see that a portion of the patients experience ... between 10 and 30 percent of the MINOCA patients, have evidence of myocarditis, although it was not clinically expected.
So this is a heterogeneous population ... initial diagnosis was myocardial infarction.
Dr Carolyn Lam: Thank you for clarifying what you used in your study. Gabriel, could I just, you know, bring you in on this because you invited an excellent editorial that accompanies this paper. And, basically, it helps to get us past all this terminology you know, MINOCA now. Could you maybe just clarify the overall perspective of what it means?
Dr Gabriel Steg: Yeah. This area is fairly new and we still have a major nomenclature problem. Clearly it's been recognized for many years that patients who have a clinical syndrome of myocardial infarction do not necessarily have obstructive coronary artery disease. At least severe obstructive coronary artery disease. Many patients have mild lesions and some patients apparently have no lesion at all.
Now, over the last few years we've understood that this is really a syndrome. And that under that big umbrella, there are patients who have non-cardiac causes of troponin elevation and chest pain. These should be excluded from MINOCA. If you have pulmonary embolism, this is not MINOCA. This is pulmonary embolism.
The second aspect is there are more subtle distinctions to be made with fairly new entities such as Takotsubo. When this study was started, Takotsubo was an emerging disease concept. And so the authors were not able to properly rule out the Takotsubos and probably a few myocarditis from their data set. We now have learned over the past few years that MRI is an excellent tool to screen MINOCA patients and flush out patients who have myocarditis or Takotsubo, which are not rare. Actually it's a substantial portion of that entity.
And then we're left with what I call the true MINOCA. Now what's fascinating in the study here is really that ... first of all I want to say this is another great study from our Swedish colleagues leveraging their data collection tools, which are remarkable. Really an example to the world.
The second thing is they have collected ten years of data on MINOCA. And they're able to tease out which are the agents that should be using secondary prevention in that population. Elegantly demonstrating with sensitivity analysis and positive and negative controls what are the agents associated with improved outcomes and what are the agents that apparently do not impact outcomes.
So even though at the time they were not able to rule out myocarditis and Takotsubo properly, still the sheer size of their study, long term follow up, and the careful statistical analysis that they've done are remarkable.
Dr Carolyn Lam: I couldn't agree more. And more so in an area that is really emerging in importance. And for which we don't have any prospective clinical trials. I'm correct in saying that, right ? So Bertil, this would be a great point for you to let us know what are the main findings from your study please.
Dr Bertil Lindahl: The main findings are that statins are associated with a beneficial effect on the cardiac event. And also, ACE inhibitors or ARBs , while we were not able to show statistically things you can affect with beta blockers and similarly not with dual anti-platelet treatment. So that's basically the main findings of the study.
Dr Carolyn Lam: May I ask how have these findings personally impacted your clinical practice or do you think the next steps are gaps that need to be addressed first?
Dr Bertil Lindahl: I think that's an ongoing discussion in Sweden now and in our hospital on how this should be applied to clinical practice. Nothing. It will have an effect that statins and ACE Inhibitors or ARBs will be used. I'm not sure whether we still can say that we should not use beta blockers or dual antiplatelet treatment. But I think also that we are now discussing we should do a randomized clinical trial to really tease out whether we should use beta blockers or not or also verifying the findings regarding ACE Inhibitors and ARBs.
So, I think there's always a discussion whether we can really use observation studies for treatment decision. But I think since we don't have any better trials so far I think that this is the best that we can get. So I think it will be used and applied in clinical practice.
Dr Carolyn Lam: Indeed. I really agree with what Gabriel said this is the best available evidence we have now. And my personal take home message was to pay more attention to the statins and the ACE Inhibitors. So congratulations on this great study.
Gabriel, what do you think? What are next steps? I mean, MINOCA's not even in the guidelines now. Our guidelines talk about type 1, type 2, AMI ...how does it all fit in?
Dr Gabriel Steg: Well, we've seen a sea change in the concepts regarding myocardial infarction over the last fifteen years with the advent of troponin and the ability to diagnose new patients that previously we wouldn't even label as an MI.
The second aspect is we've recognized over the years that there are some genuine MI's that don't have severe obstructive coronary artery disease. Now what's interesting is that some of them may have apparently mild obstructive disease. Which presumably is related to coronary dissections, embolism, plaque rupture with thrombosis that disappeared in the interim. And some of them may have actually "clean" coronary arteries and have myocardial infarction related to other mechanisms such as micro vascular mechanisms. What's interesting, and I'd like to ask the opinion of Dr. Lindahl is, these three types of diseases; mildly obstructive disease, coronary dissection, and microvascular angina are all more frequent among women. And I wonder whether you have any insights regarding gender differences in your registry.
Dr Bertil Lindahl: In this study, in the sub-group analysis we saw no significant interaction between gender and the effects. But unfortunately we don't have the registry information between , let's say completely "normal coronary arteries" versus "mildly obstructed coronary arteries". And that's a clear limitation of this study. It will be very interesting to see whether these effects are similar in these two sub-groups.
It seems from other studies that approximately fifty percent of the MINOCA patients that have normal coronary arteries and fifty percent that have mild aortic disease. So this is a limitation of this study and I think that's just something we have to look for in the future. And I hope that we will have in the registry onwards, data on whether this normal or mild coronary artery disease.
Dr Carolyn Lam: Really appreciate that and really appreciate the insights you gentlemen have shared. Any final words or concluding remarks, Gabriel?
Dr Gabriel Steg: Well, again congratulations on the great study. I would refer our readers to the excellent editorial of John Beltrame that accompanies this paper, which reviews the concepts of MINOCA, the nomenclature, and some of the remaining and lingering questions that plague the field. And delineates way forward for studies.
I think it's a fascinating area. I'm sure we're going to hear a lot more, both from the Swedish Heart Registry as well as other data sources. I think we all need to stay tuned to this important area. The prognosis of these patients is not so good, so we need to pay attention to that entity.
Dr Carolyn Lam: Wonderfully put. Well, thank you listeners for joining us this week. Please share this episode with all of your friends. So thank you and join us next week.
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.
Today's issue features two exciting papers regarding heart failure in patients with breast cancer. We will be discussing this right after these summaries.
Are we any closer to improving survival in Eisenmenger syndrome? Well, today's first original paper looks at contemporary trends and presents a multivariable mortality risk stratification model based on five simple noninvasive predictors of death in this population. Dr. Kempny and colleagues from Royal Brompton Hospital in London in the United Kingdom preform a large multicenter study in 1098 patients with Eisenmenger syndrome followed up between years 2000 and 2015.
At the end of the study almost two-thirds of patients were on advance therapy for pulmonary arterial hypertension, while only six patients underwent lung or heart and lung transplantation. The study showed that despite advances in management, there was significant mortality amongst contemporary adults with Eisenmenger syndrome and 25.3% of patients died over a median follow up period of 3.1 years. Mortality was higher in older patients, those with a pre-tricuspid shunt, lower oxygen saturation, absence of sinus rhythm, or with a pericardial effusion.
This important study is accompanied by an editorial by Drs. Lange, from Texas Tech University Health Sciences Center El Paso and Dr. Brickner from UT Southwest Medical Center in Dallas, Texas. The editorialists call for a prospective randomized control trials of the effect of current, or future pulmonary vasoactive disease targeting therapies on mortality in Eisenmenger syndrome patients, and say it's time to direct our efforts from improving risk-stratification towards improving survival.
The next study provides experimental evidence of tolerogenic dendritic cell therapy as a novel anti-remodeling therapy in myocardial infarction. Tolerogenic dendritic cells are promising, potent, beneficial regulators of the post-infarct healing process via their control of T-regulatory cells and M1 M2 macrophages. Plus they have the advantage of the ease of administration and feasibility of a heart specific tolero-dendritic cell production.
In the current paper by co-first authors, Drs. Choo and Lee, and co-corresponding authors, Drs. Chang and Lim, from Catholic University Korea and Chai University in Korea, authors generated tolerogenic dendritic cells by treating bone marrow-derived dendritic cells with TNF-alpha and cardiac lysate from mice with myocardial infarction. They then injected myocardial infarction mice twice with tolerogenic dendritic cells within 24 hours and at 7 days after LAD ligation. In treated animals, in vivo cardiac magnetic resonance imaging and ex vivo histology confirm the beneficial effects on post-infarct LV remodeling. Furthermore, subcutaneously administered tolerogenic dendritic cells near the inguinal lymph node migrated to the regional lymph nodes and induced infarct tissue specific T-regulatory T-cell populations in the inguinal and mediastinal lymph nodes, spleen, and infarcted myocardium, all of which elicited an inflammatory to reparative macrophage shift. The altered immune environment in the infarcted heart resulted in better wound remodeling, preserved left ventricular systolic function, and an improved survival following myocardial infarction. Thus, this study shows that tolerogenic dendritic cell therapy in a preclinical model of myocardial infarction may be potentially translatable into an anti-remodeling therapy for ischemic repair.
The final paper reports results of cell therapy on exercise performance and limb perfusion in peripheral artery disease from the PACE trial, which is an NHLBI-sponsored randomized double-blind placebo-controlled phase two clinical trial, designed to assess the safety and efficacy of autologous bone marrow-derived aldehyde dehydrogenase bright cells in peripheral artery disease, and to explore associated claudication physiological mechanisms. In this paper from corresponding author Dr. Moye from UT School of Public Health in Houston, Texas and colleagues of the Cardiovascular Cell Therapy Research Network, a total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at nine sites to receive alcohol dehydrogenase bright cells or placebo. All patients underwent bone marrow aspiration and isolation of aldehyde dehydrogenase bright cells followed by 10 injections into the thigh and calf of the index leg. Results showed that there were no significant differences in the change over six months between study groups for the co-primary endpoint of peak walking time, collateral count, peak hyperemic popliteal flow, and capillary profusion measured by magnetic resonance imaging.
Additionally, there were no significant differences for the secondary endpoints including quality of life measures. There were no adverse safety outcomes. Interestingly, a post-hoc exploratory analysis suggested that aldehyde dehydrogenase bright cell administration might be associated with an increase in the number of collateral arteries in participants with completely occluded femoral arteries.
In summary, cell therapy did not improve peak walk time or magnetic resonance outcomes, and the changes in peak walk time were not associated with the anatomic or physiologic MRI endpoints. However, future peripheral artery disease cell therapy trial design may be informed by new anatomic and perfusion insights. These and other issues are discussed in an accompanying editorial by Drs. Breton-Romero and Hamburg from Boston University School of Medicine. Well, that wraps it up for our summaries, now for our feature discussion.
We are really in the grove here in Washington, D.C. and I am borrowing the words of my very special, star associate editor, guest, Dr. Gregory Hundley, and he's from Wakefield University School of Medicine. We're discussing two very important papers and they deal with the risk of heart failure following breast cancer. Why they're so important? Well, first of all, it's about time we looked at this problem in detail, and secondly, they actually represent papers in a new section of the journal called "Bridging Disciplines," and in this case cardio-oncology. Very, very important topics.
We're here with the corresponding authors of both papers, Bonnie Ky from University of Pennsylvania School of Medicine and Dr. Margaret Redfield from Mayo Clinic.
Dr Gregory Hundley: Thank you, Carolyn. I really appreciate that wonderful introduction and also the chance to talk with Bonnie about this exciting topic.
So, Bonnie, you've got a paper here, now, where you did a study in patients with breast cancer, and it sounds like you acquired echocardiograms over a period of time. Can you tell us a little bit about that?
Dr Bonnie Ky: Correct. So this is longitudinal prospective cohort study, it's an NIH-funded R01, whereby we are enrolling patients from the breast cancer clinic who are receiving doxorubicin or trastuzumab or a combination of the two therapies. And we're performing very careful cardiovascular phenotyping, from the time at which they initiate chemotherapy through their chemotherapy and then annually once a year we have them come back, for a total follow up time of 10 years.
We took a subcohort, 277 patients, and from their echocardiograms, we analyze them very carefully for various measures of left ventricular size, function, not only systolic function but also diastolic function. We also looked at measures of contractility such as strain in multiple dimensions, and then also measures of ventricular arterial coupling, as well as arterial loads, so how the ventricle interacts with the arterial system. And what we found was that over a 3.2 period time period, on population average, these modest declines in left ventricular ejection fraction, and even across all three treatment groups, and even at three years there were persistent LVF declines.
Dr Gregory Hundley: So, I understand, Bonnie, that you also collected some information as to whether or not these patients were experiencing symptoms associated with heart failure. How did the imaging markers relate to the symptomatology associated with heart failure?
Dr Bonnie Ky: What we found was that early changes in arterial stiffness or total arterial load, as well as early changes in EF were associated with worse heart failure symptoms at one year. A lot of our other analysis was focused on defining what echo parameters of remodeling, size, function are driving or associated most strongly with LVF decline, as well as LVF recovery.
Dr Gregory Hundley: And then at two years, what happened? Did the echo parameters, were they still associated with heart failure or was there a little discrepancy there?
Dr Bonnie Ky: Interestingly, at two years ... no, there was no significant association with changes in arterial load and heart failure symptoms at two years.
Dr Gregory Hundley: So there might be something transient that's occurring that is associated with heart failure early, and then the patients still had heart failure late, so maybe something else is operative. What do you think we need to do next? What's the next step in your research and then other investigators around the world; what do we need to do to design studies to look at these issues further?
Dr Bonnie Ky: Yeah. What does the field need, the field of cardio-oncology that's really growing and developing at rapid paces. Some of the major findings from the study was that changes in total arterial load were very strongly associated with both LVF decline and LVF recovery. So total arterial load is the measure of blood pressure or total arterial stiffness, it's derived from blood pressure. And to me, that begs the question, or begs the next step is that changes in blood pressure are associated with decline as well as recovery. I think, oh, as cardiologists we've also always recognized the importance of afterload reduction. And to me, this study suggests that we need a study, a randomized clinical trial, looking at blood pressure lowering in this population to help mitigate LVF declines.
Dr Carolyn Lam: I'd actually like to turn it back to you. You are world-renowned for your work in cardio-oncology. Where do you think this fits in, and where do you think we need to address most urgently?
Dr Gregory Hundley: I think where this fits in wonderfully is a lot of individuals around the world are collecting echocardiographic measures, and all different types. And what Bonnie has helped do is clarify what we would expect to see in this particular patient population. How those measures change over time and that feeds into another block of data, when the measurements head south, do we change therapy, do we add protective agents, and things of that nature. So I think Bonnie's work really contributes on that front. What she has also pointed out is that more research needs to be performed, not necessarily because the patients had heart failure symptomatology at two years, but not necessarily associated with the decline in EF; are there other systems in the cardiovascular realm that are being affected? The vascular system-
Dr Carolyn Lam: Yeah.
Dr Gregory Hundley: Skeletal muscle, many other areas. So as cardiologists start to work more with oncologists in this space, and we're all working together to make sure that not only patients survive their cancer, but they have an excellent quality of life, I think we'll see, as we have in other heart failure syndromes, a look toward other aspects of the cardiovascular system, body in general, to reduce the overall morbidity associated with the disease.
I think what we need to recognize as cardiovascular medicine specialists is that now for many forms of cancer, cardiovascular events, and certainly morbidity are becoming the primary issue that folks have to deal with with survivors. It's not necessarily the cancer recurrence, it's not necessarily a new cancer, it's cardiovascular. So we've got to integrate cardiology earlier in working with oncologists to improve overall survival and create an excellent quality of life from our different perspectives.
Dr Carolyn Lam: So, Maggie, let's move on to your paper now. You looked at radiotherapy's effect, whereas Bonnie looked at chemotherapy's effect. Could you tell us what you did and what you found?
Dr Margaret Redfield: The rationale for doing this study was, of course, seeing a lot of patients with HFpEF who had had radiation therapy for breast cancer, and I always just sort of assumed that that was because 12% of women over the age of 40 get breast cancer and 20% of women over the age of 40 get heart failure, but it seemed to be somehow more common than that. The other rationale was that radiation therapy does not actually affect the cardiomyocytes; they are very radiation resistant. And what radiation does is cause microvascular endothelial cells damage and inflammation, and that is felt to be fundamental in the pathophysiology for HFpEF.
So we thought we should look at this. I collaborated with a radiation oncologist and oncologists, and they were interested in looking at this because there's a lot of techniques now to reduce cardiac radiation exposure during radiation therapy, including proton beam therapy, and they're trying to prioritize who they use this new technology on. So what we did was start with a population-based study, all women who lived in Olmsted county who received radiation therapy for breast cancer in the contemporary era, where they're already using these dose reducing techniques. So we wanted to make it relevant to what's going on today. And so we started with a base cohort of all women. We matched patients' cases, it was a case-control study, so we matched cases and controls according to their age at the time of breast cancer, whether they had heart failure risk factors, like hypertension or diabetes, whether they got adjuvant chemotherapy, and tumor size, because we felt it was important that radiation could affect different parts of the heart, depending on whether it was right- or left-sided tumor.
And what we found is that the risk of heart failure increased with the mean cardiac radiation dose. We measured the mean cardiac radiation dose in every case and every control from their CT scans and their radiation plants. And as the radiation dose went up, the risk of heart failure went up, even matching or controlling for chemotherapy, which wasn't used that often in this group, or heart failure risk factors. And the vast majority of these cases were indeed HFpEF.
So we then looked at factors that happened in-between the radiotherapy and the onset of heart failure, making sure that this all wasn't just coronary artery disease, 'cause we know radiation can increase the risk of coronary artery disease. And indeed there were, only in about 18% of cases was there a new episode of coronary disease in the interim between the radiotherapy and the breast cancer. So, basically found that the mean cardiac radiation dose, even in today's era, does increase the risk of heart failure with preserved ejection fractions.
Dr Carolyn Lam: The things that stuck out to me ... it's population based. You did such a comprehensive study to really answer very key questions: dose of radiation, is it really just mediated by age and age-related risk factors, is it just about MI or could it be more microvascular disease? Congratulations, I really appreciated this paper. Some of the take-home messages are directly related to the treatment of breast cancer, isn't it? And about the importance of minimizing radiation dose if possible. I suppose one of the take-homes is, as well, for screening and watching out for heart failure. One thing though: how were these woman diagnosed with HEpEF? I mean, this is always the questions I get. How do you get diagnosed with HEpEF?
Dr Margaret Redfield: Right, well, first we started with looking to see if they had a ICD code for heart failure, and then we looked at each case of heart failure and determined if they either met Framingham criteria at the time of the diagnosis and the majority of them did. If they didn't actually meet the Framingham criteria, we looked to be sure there was a physician diagnosis of heart failure in the record and that they had supportive evidence of heart failure: echocardiographic findings, natriuretic peptide findings, and other clinical characteristics of heart failure.
And importantly, in the large control group from where we, you know, got our controls, people, a very large group of patients who did not get heart failure, we'd use natural language processing to look at all those records to make sure we weren't missing anybody who didn't have an ICD diagnosis or code for heart failure to make sure we weren't missing any cases of heart failure. So, we really tried to use very stringent methods to make sure we had true cases and control groups.
Dr Carolyn Lam: Indeed, and it actually goes back to Bonnie's paper as well, where we have to remind everyone that the diagnosis of HEpEF really starts with the symptomatology of heart failure in particular, that you so rigorously determined. I think just one last thing, Maggie: what do you think this implies now, for HEpEF? What do we do in general so the non-radiation-associated, do we believe more the Walter Paulus-Carsten Tschope hypothesis, and if so, what do we do?
Dr Margaret Redfield: Yes, well I think it really does support that hypothesis. We know that radiation therapy, again, we know what it does to the coronary microvascular endothelial cells and that's been elegantly worked out both in patients and in animal models. I think this really supports the Paulus hypothesis because this microvascular damage was able to produce heart failure, so I think that really supports that hypothesis. And there's been some studies showing decreased coronary flow reserve in HEpEF patients; it's very common. So I think indeed it does support that hypothesis and that the coronary microvasculature is key in the pathophysiology of HEpEF.
However it's a little scary to me because that sort of damage, once it's established, may be very hard to treat. You know, proangiogenic strategies in peripheral vascular disease have not yet yielded the benefits that we hoped for, so I think it's a tough therapeutic challenge that'll be very important to try to address in pre-clinical studies to try and figure out once the microvasculature is so damaged how do we treat that? How do we reverse that process?
Dr Carolyn Lam: Yeah. Words of wisdom. Maggie, thanks so much for inspiring, just all of us in this field. I just had to say that. You know, you are the reason that I am totally in love with HEpEF. (laughter)
Dr Margaret Redfield: (laughter)
Dr Carolyn Lam: So thank you so much for joining me today on the show. In fact, thank you to all my three guests.
You've been listening to Circulation on the Run. You must tell everyone about this episode, it is full of gems.
Thank you, and tune in next week.
Carolyn: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to The Journal and its editor's. I'm Dr. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. Our Journal this week features important new data telling us that a common genetic variant risk score is associated with risk of drug induced QT prolongation and torsades de pointes.
First, let's give you your summary of this week's journal. The first paper provides both clinical and experimental data to show that the adipokine, retinal binding protein four promotes atherosclerosis. First author, Dr. Liu, corresponding author, Dr. Xia and colleagues from Sun Yat Sen University in Guangzhou, China first evaluated the association between serum retinal binding four levels and the incidents of adverse cardiovascular events in a community based prospective cohort and then examined the effects of retinal protein four gain or loss of function on macrophage foam cell formation and atherogenesis in an apple lipase protein E deficient mouse model. They found, in the clinical cohort study, that base line serum retinal binding protein four level was an independent predictor of incidents of adverse cardiovascular events after adjustment for traditional risk factors.
In the experimental study's, they showed that retinal binding protein four promoted macrophage derived foam cell formation through the activation of scavenger receptor CD36 mediated cholesterol uptake. In turn dependent on June and terminal kinase and signal transducer and activator of transcription one, as well as upstream regulation by the tracing kinase CSRC. These findings, therefore, support the use of retinal binding protein four as a novel biomarker for the prediction of cardiovascular risk. The data also provide insight into the mechanism of action of retinal binding protein four in the path of physiology of atherosclerosis.
The next paper is the first clinical trial, looking at remote ischemic pre conditioning prior to carotid artery stinting in patients with severe carotid artery stenosis. Remote ischemic pre conditioning is a protective, systemic strategy by which cycles of bilateral limb ischemia are applied briefly to confer protection from subsequent severe ischemia and distant organs. First author, Dr. Zhao, corresponding authors, Dr. Ji, and colleagues from Xuanwu Hospital, Capital Medical University in Beijing, China performed a proof of concept, single center, prospective, randomized control trial to assess whether remote ischemic preconditioning was safe and effective in attenuating ischemic injury related to carotid artery stinting in 189 patients with severe carotid artery stenosis. Results show that daily remote ischemic pre conditioning for two weeks, prior to carotid artery stenting, was feasible, safe, well tolerated, and may effectively attenuate secondary brain injury as evidence by a decreased incidence and reduced volumes of new ischemic legions on magnetic residence imaging performed within 48 hours post operation. The clinical implications are that if results are confirmed by future, larger studies, remote ischemic preconditioning may evolve into a nonpharmacological, neuro protective method for inhibiting carotid artery stenosis related cerebral ischemic events.
This potential for clinical translation in discussed in an accompanying editorial by Doctors Bell and Yellen, from University College, London.
The final paper discusses firefighting and the heart. What's the link? Well, cardiovascular events are the leading cause of death amongst firefighters and the risk is known to be substantially increased during fire suppression duties. In the current study, first author Dr. Hunter, corresponding author, Dr. Mills, and colleagues from University of Edinburgh in United Kingdom sought to understand this link better by assessing the effects of simulated fire suppression on measures of cardiovascular health in an open label, randomized cross over study of 19 healthy firefighters. These firefighters performed a standardized training exercise in a fire simulation facility or like duties for 20 minutes. Following each exposure, ex vivo thrombus formation, fibrinolysis, platelet activation and for armed blood flow in response to intra-arterial infusions of endothelium dependent and independent vasodilators were all measured. The authors found that exposure to extreme heat and physical exertion during fire suppression activated platelets, increased thrombus formation, impaired vascular function, and promoted myocardial ischemia and injury in healthy fire fighters. These finding provided pathogenic mechanisms to explain the association between fire suppression activity and acute myocardial infarction in fire fighters.
The implications of these findings for prevention are discussed in an accompanying editorial from Dr. Kales, of Harvard school of Public Health and Dr. Smith from Skidmore College and University of Illinois fire service institute.
Well, those were your summaries. Let's welcome our guests for our feature discussion.
Today's feature paper describes a pilot study that shows that a common genetic variant risk score, is associated with drug induced QT prolongation and torsades de pointes. This paper is so interesting to me because I found that the learning points, at least for me, really extended well beyond the trial itself. I'm so delighted to have with me the co corresponding authors, Dr. David Strauss from the US FDA, as well as Dr. Christopher Newton-Cheh from Massachusetts General Hospital. Welcome, gentlemen.
David: Thanks very much, glad to be here.
Christopher: Thank you, Carolyn.
Carolyn: So, I've always thought that common genetic variants identified via GWAS, for example, are individually very weak effects on medical traits. For example, systolic blood pressure or in this case, QT interval. But what I'm so impressed with this study is that you show, I think for the first time, that even these small effects can add up to clinically meaningful results that are testable or demonstrable in a trial. David, could you begin by telling us a little bit about this trial and what the primary results were.
David: In the study, we tested the hypothesis that a weighted combination of common genetic variants, contributing to the QT interval at base line, identified through prior GWAS studies, can predict individual response to multiple QT prolonging drugs. We performed a genetic analysis of 22 subjects and a secondary analysis of a randomized, double blind, placebo controlled cross over trial, that included three QT prolonging drugs, with 15 tie matched QT and plasma drug concentration measurements. This allowed us to carefully control for the inter individual differences in pharmacokinetics and just focus on the pharmacodynamics so the direct effect of the drug on the heart.
What we found was, there was a significant correlation between the weighted combination of common genetic variants, which we call the genetic QT score, and drug induced QT prolongation. More specifically, we found that the genetic QT score explained 30 percent of the variability in response to dofetilide, 23 percent in response to quinidine, and 27 in response to ranolazine.
We also investigated how response to one QT prolonging drug predicted the response to other QT prolonging drugs. There were significant correlations between all the drug/drug relationships with response to each drug explaining 24 to 29 percent of the variability in response to each of the other drugs. It's important to note that QT prolongation, by itself, is not harmful. The real concern is torsades de pointes, which can degenerate into ventricular fibrillation and cause sudden death. So, the test, irrelevant to the common genetic variants in predicting drug induced torsades, we then went on to examine a previously published, genome wide association study that included 215 patients with drug induced torsades, compared to 771 ancestry match controls and that prior study that was previously published had found that each individual common genetic variant did not reach genome wide significance, as you suggested, Carolyn. However, when we applied the weighted combination of common genetic variants, we found that the genetic QT risk score was associated with significantly increased risk of drug induced torsade, explaining 12 percent of the variation in risk.
Carolyn: So, my simplistic understanding was more or less there. That these genetic risks of these common variants kind of add up. I'm just curious ... Chris, do you think that this has implications for even other diseases? That's one question. And then secondly, I really appreciated your comment about using an intermediate trait, if you may, of QT interval versus looking at the disease itself of torsade de pointes. Could you give me comments on both these things?
Christopher: The study of intermediate traits, such as, quantitative traits like QT variability on the EKG are, I think very tractable for the study of genetic bases of underlying physiologic processes because we can study so many people. So the original genome wide association study that detected these individually weak genetic effects could only find them because we studied about 75,000 people who had had genome wide genome typing and QT intervals measured. It requires such large sample sizes to reach p values that are able to distinguish true positive associations from false positive associations, due to the multiple testing burden.
I think a challenge of what to do with these genetic effects once they've been reliably detected is that they do have weak effects and they influence intermediate traits. Nobody really cares whether their QT interval is three milliseconds longer, or three milliseconds shorter. What they care about is hard outcomes, or the likelihood that they'll have a toxic drug response. So, it was a natural follow on to that work to try to test these variants, and we knew that based on their weak effects individually on QT interval in the general population, that it was unlikely that they would individually explain a significant portion of either drug response or torsade. Which is why we aggregated the facts into the weighted score.
I think we tried to examine what we thought were the most proximal, clinically relevant outcomes. Specifically, drug response. QT drug response to drugs that are established to cause QT prolongation and arrhythmias. Whether the QT score will have meaningful or detectable impact on drugs that have much weaker effects on re polarization and risk of torsade, I think, would remain to be seen.
Carolyn: That's really remarkable.
David, how about your perspective of the implications of this? It's so unique that you're actually from the FDA so, why is this important to the FDA?
David: As Chris mentioned, the specific application we studied here, a drug induced QT prolongation and torsade have resulted in the withdrawal of several drugs from the market both in the US and worldwide. Many critical drugs remain on the market that are associated with QT prolongation and torsade…over 100 drugs, likely. What some people may not be familiar with is that at FDA we perform research to move new science into the drug review process and close the gap between scientific innovation and drug review. Like practicing clinicians, we seek to understand inter patient variabilities and we conduct research to better evaluate, benefit, and risk of medications. This is in line with the broader initiative ... the precision medicine initiative, which seeks to move away from the traditional “one size fits all” approach for medical therapy and instead, take into account specific characteristics of individual patients.
People are most familiar with this being applied in oncology and advances in pharmacogenomics have been more limited in other areas with the exception of the genetic bases of metabolism and pharmacokinetics where the traits are often controlled by one or a few genetic mechanisms, rather than the many mechanisms responsible for complex traits and diseases, as Chris discussed. As I mentioned earlier, what was relatively unique about this study is that we were able to control for the difference in pharmacokinetics and investigate the inter individual differences in the direct effect of drugs on the heart, the pharmacodynamics. We think it's very exciting that a combination of common genetic variants and aggregate can explain a significant portion of the inter individual variability and, as Chris mentioned, this is also important because the incidence of torsade is quite low. Only a small number of patients will develop drug induced torsade. It's possible that in the future analysis of a large number of common genetic variants that can be identified through genome wide association studies as in this case, may help to better define the personalized benefit risk profiles for individual patients.
Carolyn: You've really articulated that remarkably. That's exactly the excitement I think the entire editorial team shared when we read your paper. Thank you so much for it. Maybe just one last question thrown out to both of you, what's the next step? What's in the future.
Christopher: I think one next step, based on this proof of principle study, will be to try to test the impact of these genetic risk scores in real world clinical settings where individual patients with the diversity of different comorbidities and different drug exposures are also receiving QT prolonging drugs. Because that will have the biggest relevance for our patients who faced increased risk of drug toxicity.
David: The issue of cardiac safety of drugs is something that is very important to us at the FDA and we have some parallel initiatives that, in collaboration with other global drugs ... regulatory agencies and industry and academic collaborators ... we are working to develop new cardiac safety evaluation paradigms for new drugs, or existing drugs, that could even be applied in the preclinical setting and really focus on the mechanistic base, pro arrhythmic risk. So, we should have more exciting work coming forward in the near future for better prediction and individualized prediction of benefit and risk of medication.
Carolyn: Thank you, listeners, for joining us. You've been listening to Circulation on the Run. Join us next week.
Caroline: 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. Up next, we are discussing the featured paper in this week's journal regarding the increased risk of cerebrovascular events in young cancer survivors, the downside perhaps of surviving cancer, so to speak. But first, here's your summary of this week's journal.
The first paper describes the US national trends in atrial fibrillation hospitalization, readmission, and mortality. This paper from Dr. Freeman and colleagues of Yale University School of Medicine in New Haven, Connecticut used data from all Medicare fee-for-service beneficiaries between 1999 and 2013, and found that the adjusted rates of hospitalization for atrial fibrillation increased by almost 1% per year. Median hospital length of stay remained unchanged at three days, but median Medicare inpatient expenditure per beneficiary increased from $2,932 to $4,719 per stay.
During the same period, the rate of inpatient mortality during hospitalization for atrial fibrillation decreased by 4% per year, and the rate of 30-day readmission also decreased by 1% per year, while the rates of 30-day and one-year mortality decreased more modestly by 0.5% and 0.26% per year, respectively. Thus, between 1999 and 2013, among Medicare fee-for-service beneficiaries, rates of hospitalization for atrial fibrillation and the cost of those inpatient stays increased substantially, but this was associated with improved outcomes, including lower rates of readmission and mortality. These findings suggest that increased hospitalization and more costly contemporary treatments, such as atrial fibrillation catheter ablation, may be associated with improved outcomes.
The next study provides insights into the mechanisms underlying augmentation of muscle blood flow by ultrasound cavitation of microbubbles. Now, this is a promising approach for rapidly correcting tissue profusion in acute ischemic syndromes or for treating chronic ischemic symptoms. In this paper by first author Dr. Belsik, corresponding author Dr. Linder, and colleagues from Night Cardiovascular Institute Oregon Health and Science University in Portland, Oregon, the authors hypothesized that pure endergic signaling may be responsible for sheer dependent increases in muscle profusion during therapeutic ultrasound cavitation.
To test this hypothesis, the authors studied unilateral exposure of the proximal hind limb of mice with and without ischemia produced by iliac ligation, to therapeutic ultrasound after intravenous injection of lipid microbubbles. They further performed a proof of concept study with twelve patients with stable sickle cell disease. They found that therapeutic ultrasound cavitation increased muscle profusion by seven-fold in normal mice, reversed tissue ischemia for up to 24 hours in the murine model of peripheral artery disease, and doubled muscle profusion in patients with sickle cell disease.
Augmentation inflow extended well beyond the region of ultrasound exposure. Ultrasound cavitation produced a nearly forty-fold focal and sustained increase in ATP, the source of which included both endothelial cells and erythrocytes. Inhibitory studies indicated that ATP was a critical mediator of flow augmentation. Furthermore, combined indomethacin and inhibition of eNOS abolish the effects of therapeutic ultrasound, indicating downstream signaling through both nitric oxide and prostaglandins. Thus, the authors concluded that therapeutic ultrasounds using microbubble cavitation to increase muscle profusion relies on sheer dependent increases in ATP, which can act through a diverse portfolio of purinergic signaling pathways. Cavitation-related release of ATP may further serve to explain ultrasound's role in other therapeutic applications, such as wound and bone healing, and ultrasound facilitated drug or gene uptake.
The final original paper describes the age-specific trends of heart failure in Denmark over the last two decades. Dr. Christiansen and colleagues of University of Copenhagen in Denmark studied more that 210,000 Danish individuals over the age of 18 years, with a first time in-hospital diagnosis of heart failure from three nation-wide Danish registries.
They found that the incidents of ischemic and non-ischemic heart failure in Denmark declined by approximately 50% among older adults more than 50 years old, but increased by about 50% among younger individuals, or individuals less than 50 years old, between 1995 and 2012. Furthermore, they observed a concomitant increasing trend of various treated co-morbid conditions, including hypertension, diabetes, and ischemic heart disease in the population. These findings from Denmark imply a change in the profile of the heart failure community and portend a higher burden of heart failure in the future. The increasing trend of incident heart failure among young individuals especially warrants further investigation.
Well, those were the original papers this week. Now, for our feature discussion.
Our feature paper today discusses a hugely important modern issue that may seem like good news at first sight. We know that survival in cancers has rapidly improved with advances in early detection and treatment, however the improved survival also extends the window for the occurrence of long-term complications such as psycho-social effects, fertility problems, secondary malignancies, and, as highlighted in today's paper, the risk for cerebrovascular events. I'm so pleased to have with us first, author Chloe Bright from University of Birmingham, United Kingdom, as well as associate editor Dr. Graeme Hankey from University of Western Australia. Welcome, Chloe and Grim!
Chloe Bright: Thank you for having me.
Graeme Hankey: Thank you Caroline.
Caroline: Chloe, what an interesting and important focus on cerebrovascular events following survival from cancer. Please, can you share your inspiration for looking at this and what you found?
Chloe Bright: As you've just said, the five year survival rate from teenage and young adult cancer has been increasing and increasing, and it's over 80% now, which means there's such a large population of survivors who are at increased risk, or potentially increased risk, of developing adverse health outcomes. So, as you know, cerebrovascular disease can be potentially fatal so it's really important that we estimate how much teenage and young cancer survivors are at risk of this. So to start of with our group in Birmingham actually set up the teenage and young adult cancer survivor cohort study. And this is a cohort of over 200,000 five year survivors of cancer who were diagnosed between 15 and 39 years of age. And this was set up because there's hardly any literature regarding the adverse health outcomes of teenagers and young adults who have had cancer.
So, as I said, cerebrovascular disease is a really important outcome to look at. So we decided we've got this resource in the UK, which is the Hospital Episode Statistics, and this carries information on all the inpatient hospitalizations in England. So from this we were able to determine how many people with teenage and young adult cancer had been hospitalized for cerebrovascular events and compare this to what we would expect to see in the general population to see if they had an increased risk or not. So from limited previous literature that was out there we did know that TYA cancer survivors had an increased risk of developing a cerebrovascular event. However, we were unsure how this risk varied with certain explanatory factors, such as age of cancer diagnosis or the decade of cancer diagnosis, gender, and attained age, so that's the age at which a stroke event might occur. So the main aim of our study was to quantify this.
Caroline: Yes and to put some numbers to that increased risk. It was a 40% increased risk, wasn't it? That is striking.
Chloe Bright: We observed almost 2,800 cerebrovascular events. That related to a 40% increased risk of being hospitalized compared to what we would expect to see in the general population, which is really quite substantial.
Caroline: Now, were there particular risk factors that were associated with more cerebrovascular complications like certain types of tumors or certain types of therapies and so on?
Chloe Bright: Survivors of central nervous system tumors, head and neck tumors, and leukemia were all at the greatest risk compared to the general population. And this is probably related to radiotherapy that they had for their initial treatment. So radiotherapy to the neck, which could involve damage to the carotid artery, or radiation to the head which again could cause damage to the cerebral arteries in the brain. And then also we found that the risk increased dramatically as people aged for neck tumor survivors and CNS tumor survivors. So specifically cerebral infarctions, the additional number that we saw was a lot greater in, say, survivors over age 60. And this is probably because this is when strokes in the general population are becoming more incident.
And actually an interesting finding, we observed that males actually had a higher number of excess infarctions than females, and this was especially among head and neck tumor survivors. So we can't confirm this, but this could potentially be due to difference in smoking habits because there could be a said etiology between smoking and the risk of head neck cancer and also smoking and the risk of stroke. Unfortunately, we didn't have the information on smoking status to confirm this.
Caroline: This is a huge study. It shows a substantial increased risk of stroke in these young cancer survivors, and also sheds light on the possible underlying mechanisms. What you mention about vasculopathy following radiotherapy really reminds me about what we learn about breast cancer radiotherapy and the risk of myocardial infarction.
Graeme, what are your perspectives on this paper please?
Graeme Hankey: Well as an editor, as everyone knows, what we're really looking for are four main points. Firstly that the study was ethical, which it was. Secondly that the results are valid, internally and also externally. And we're very confident in the validity of the results. This was a very large study of 180,000 people, and more importantly had 2,800 cerebrovascular events so that's a lot of [inaudible 00:12:25] and the followup was pretty rigorous over 11 years, and the outcome events were [inaudible 00:12:32] by a data linkage through the hospitalization for the cerebrovascular events.
The other two key features of course is are the results novel and are they important? And these are novel results. There's only been one previous similar study of a Danish cohort that was only 43,000 but one quarter the size of this study, and one year survivors of teenage and young adult cancer from 1943 to 2009 and followed up. And the results were actually very similar, showing a 1.3 or 30% increased risk of hospitalization for cerebrovascular events. Again supporting the validity of this recent study to obtain similar results, but in a four times greater population and in a more contemporary population whose patients were recruited between 1971 and 2006 and followed up from 1997 to 2012.
And the other thing is it's not just ethical, valid, and novel, but it's important because it really has big implications for stroke prevention in young adult survivors of cancer. And it has implications for once they get the diagnosis and they're through their treatment to really focus on what were their pre-morbid vascular risk factors? Are they actually causal risk factors and not just cancer but also for future stroke like smoking and alcohol, and hypertension and diabetes? Secondly to try and recognize what is their absolute risk? Are they men who are at higher risk? Have they had previous irradiation that probably puts them at higher risk, as well as their current respective profile?
Thirdly for them to then realize what's the impact of their cancer diagnosis on their future behaviors if they become depressed or change their diet or taking other treatments, or abusing drugs, and could that increase their vascular risk? And fourthly, what should be done? Should they just control their vascular risk factors through lifestyle? Or should we actually have a randomized trial of risk factor control, and/or antiplatelet therapy and/or statins and/or blood pressure lowering in these high risk survivors of cancer who are sill in their forties or fifties. Should they actually be taking antiplatelet therapy or statins? We probably need a randomized trial because they're high risk, we would think, or certainly a sub-population.
Caroline: Thanks Graeme for framing that so excellently. You're absolutely right that these are the things we look for in a paper as editors. And for our listeners to hear that is just so important.
Well, I'd like to hand it over to you now Chloe. What are the next steps in your mind? What are the remaining gaps in knowledge you'd like to address?
Chloe Bright: I really think it relates to what Graeme just said. We need to get the information on the specific radiotherapy, the doses that have been used, the potential lifestyle factors of these individuals to see how much of an effect that has on the risk of stroke. So potentially conduct a case control study while we're able to get this information and then use that. And then, as Graeme said, once there is more information potentially a randomized control trial might be useful. But again, I think we need some more information before we can get the go ahead to doing that.
Caroline: Great. Just one more quick question please. You know, Chloe, you found that those who were more recently treated had a higher risk of cerebral hemorrhage than among survivors diagnosed earlier. Now, did you have any postulations on why this was the case?
Chloe Bright: This increase in the hemorrhage with more recent diagnosis was actually restricted to glial tumor survivors. So one explanation that we thought might explain this was that in recent years due to advances in treatments those glial tumor survivors, glial tumors who had more advanced stage at diagnosis, potentially surviving a little bit longer, so reaching five year survival which would enter them into our study. However they potentially might be having another occurrence, which would be causing them to have a hemorrhage, which in the previous decades perhaps they wouldn't have survived that long in the first place. That's just one of many ideas.
Graeme Hankey: I think the recurrence of not just glioma but perhaps also melanoma that the survival is much greater now with new immunomodulating therapies for melanoma, we'll probably see longer survival in melanoma which typically when it metastasizes is hemorrhagic and perhaps also leukemia with thrombocytopenia, with more hemorrhage and other metathesis. The other thing it could be though is a diagnostic ascertainment bias in that I'm 60 now, and when I started neurology 35 years ago we didn't really have much brain imaging and couldn't diagnose intracerebral hemorrhage very well. And clinical diagnosis wasn't very reliable. Now the imaging which can actually distinguish hemorrhagic from ischemic stroke is much more widely available. And I suspect there's a greater increase in the diagnosis of cerebral hemorrhage now because of better imaging. We've seen that in other epidemiologic studies with that diagnostic trend.
Caroline: What excellent points. Thank you so much Chloe and Graeme.
Well you've been listening to Circulation on the Run. Thanks for joining us today and don't forget to tune in next week.
Dr. 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. In this week's issue, we are discussing if public placement of defibrillators in the community can be improved. First, here's your summary of this week's Journal.
Stroke incidents, prevalence, and risk factors have been changing over the past 50 years so do we need a more contemporaneous revised Framingham Stroke Risk profile to reflect these trends? Well the first paper in our issue looks at this and this is from first author Dr. Dufouil, corresponding author Dr. Seshadri and colleagues from the Boston University School of Medicine.
Let's first recall that the Framingham Stroke Risk profile was originally described in 1991 and integrates the effect of age, sex, and baseline measurements of various vascular risk factors such as systolic blood pressure, use of anti-hypertensive medications, left ventricular hypertrophy on ECG, prevalent cardiovascular disease, current smoking status, atrial fibrillation and diabetes all to describe the 10-year probability of incident stroke.
In the current paper, the authors updated the Framingham Stroke Risk profile using the means of risk factors that reflect current prevalence, the estimate of incident stroke to reflect current rates, and the hazards ratio that reflect current associations. They used the same risk factors identified in the original stroke risk profile with the exception of left ventricular hypertrophy. The authors compared the accuracy of the standard old risk profile with the revised new risk profile in predicting the risk of [alt 00:01:58] and ischemic stroke and validated the new risk profile in two external cohorts, the three cities and regards or reasons for geographic and ethnic differences in stroke studies.
They found that the new stroke risk profile was a better predictor of current stroke risks in all three samples than the original old Framingham Stroke Risk profile. The new stroke risk profile was also a better predictor among whites compared to blacks in the regard study. The authors therefore concluded that a more contemporaneous revised Framingham Stroke Risk profile could serve as the basis for examining geographic and racial differences in stroke risk and the incremental diagnostic utility of novel stroke risk factors.
The next study provides preclinical proof of principle that an apelin receptor agonist may be of therapeutic use in pulmonary arterial hypertension. And the agonist in this case is Elabela/Toddler or ELA, first identified as an essential peptide in the development of the heart in Zebrafish, and subsequently proposed as a second endogenous ligand at the G-protien coupled apelin receptor, which works at this receptor despite a lack of sequence similarity to the established ligand, apelin.
In this study from first author Dr. Yang, corresponding author Dr. Davenport and colleagues from University of Cambridge in the United Kingdom, ELA competed for binding of apelin in human hearts with overlap of the two peptides indicated by encyclical modeling. ELA activated G-protein and β-arrestin dependent pathways and as expression was detectable in human vascular endothelium and plasma. Comparable to apelin, ELA increased cardiac contractility, ejection fraction, cardiac output, and elicited vasodilatation in rats in vivo.
ELA expression was reduced in cardiopulmonary tissues from patients with pulmonary arterial hypertension and in rat models. Finally, ELA treatment significantly attenuated the elevation of right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling in monocrotaline exposed rats. Thus, these results suggest that a selective agonist that mimics the action of indulgence ligand apelin or Elabela/Toddler, ELA, may be a promising therapeutic strategy in the treatment of pulmonary arterial hypertension.
The final paper looks at sudden cardiac death after coronary artery bypass grafting, its incidents, timing, and clinical predictors. First author Dr. Rao, corresponding author Dr. Velazquez and colleagues from Duke Clinical Research Institute in Durham, North Carolina, looked at the patients enrolled in the STICH, or Surgical Treatment of Ischemic Heart Failure Trial who underwent coronary artery bypass grafting with or without surgical ventricular reconstruction. They excluded patients with a prior ICD and those randomized only to medical therapy. Over a median followup of 46 months, 113 out of 1,411 patients who received coronary artery bypass surgery, had sudden cardiac death while 311 died of other causes.
The five-year cumulative incidence of sudden cardiac death was 8.5%. In the first 30 days after bypass surgery, sudden cardiac death accounted for 7% of all the deaths. The numerically greatest monthly rate of sudden cardiac death was in the 31 to 90 day time period. In multivariable analysis end-systolic volume index and BNP were the most strongly associated with sudden cardiac death. Thus, this study shows that the monthly risk of sudden cardiac death shortly after bypass surgery among patients with a low ejection fraction is highest between the first and third months, suggesting that risk stratification for sudden cardiac death should occur early in the post-operative period, particularly in patients with an increased preoperative end-systolic volume index and/or an increased BNP.
Well, that wraps it up for you summaries, let's turn to our feature paper.
I love our feature paper this week. You know why? It actually tells us what Tim Hortons, Starbucks, Second Cup and ATMs may have in common and may have to do with sudden cardiac death. Indeed, our feature paper actually tells us that coffee shops and ATMs may be the best spots to place AEDs at, well at least in Toronto. And to discuss this really interesting paper, I have the corresponding author, Dr. Timothy Chan from University of Toronto as well as Dr. Sana Al-Khatib, welcome again Sana, Associate Editor from Duke University, welcome to you both.
Dr. Al-Khatib: Thank you, my pleasure.
Dr. Chan: Thank you, very nice to be here.
Dr. Lam: So Tim, was that an interesting enough lead up? I mean you have to tell us about your study, it is so fascinating.
Dr. Chan: I'm very pleased that you find it interesting and not just us. So we undertook this study, we started this actually a couple of years ago, and we've been working on this issue of defibrillator location optimization for several years, and we've been talking and we have meetings in coffee shops and we were just wondering one day, what would be the risk or the coverage provided by all these different well-recognized location types around the city, and that was really the motivation that got us started looking at this study.
Dr. Lam: Tell us what you did and also how it differs from the study you did that was published in 2016 where you also reported on the spatial temporal analysis of registered AEDs in Toronto. The current study clearly extends it, but could you clarify to us all how it does?
Dr. Chan: Maybe just give a little bit of a background and context with regards to other literature that's similar. There have been studies in the past that looked at what we would call spatial coverage of cardiac arrest, so they looked at different broad location types and they tried to calculate, they basically calculated how many cardiac arrests happened, let's say within 100 meters of those location types. And what we've done here is we've extended that in a couple of directions. The first direction is looking at spatial temporal coverage and so this is not just in the nearby vicinity, IE, 100 meters, but also that cardiac arrests happen when that nearby location that had the AED was open. So if a cardiac arrest happens, but for example, let's say there's a coffee shop that actually has an AED and that coffee shop is closed, it's almost as if that AED is not even there. So one of the major things we made sure to include was this idea of temporal coverage as well, on top of the spatial.
The second major difference I would say would be the fact that we're really looking at more granular location types, so you mentioned a few businesses in your opening such as Tim Hortons and Starbucks and so on, which are coffee shops, and so one of the things that we find is when we look at very broad location types, we tend to aggregate together lots of different types of businesses. For example, if you think about a restaurant, there are many different types of restaurants that get lumped in to this category, and they do have different cardiac arrest coverage associated with them. So by breaking it up into smaller location types, we wanted to get a better idea of the risk at different locations and if you also think about one of the long term goals of this work would be to try and help policy makers identify promising partners to partner with for, let's say public access defibrillation programs, by identifying specific businesses or municipal locations, it might actually give them better targets to try and pursue rather than let's say a group of different businesses.
Dr. Lam: That makes so much sense and it really just seems like such an important public health message as well. The sensible part being of course, if you have an out of hospital cardiac arrest, you need an AED that's both nearby and available, so that was really clever. Sana, could you give us your take on the public health implications of Tim's findings?
Dr. Al-Khatib: I think the public health implications of this work can be vast and if you look at what he's done in terms of ascending to out of hospital cardiac arrests a lot of initiatives have been launched to try to improve the outcomes of patients who have the out of hospital cardiac arrests. Unfortunately despite all the work that has been done and all the wonderful initiatives that have been launched, we still have a lot of work to do to improve the survival of those victims. So certainly a crucial step is how we deploy AEDs in a strategic way based on data and evidence such as these data that are provided to us by Tim and his colleagues.
I think this is very clever, I do agree that we have to be more strategic in how we deploy AEDs and having the data such as these will only help us improve and get better of course. Everybody has limited resources, and so if we can be more selective in terms of how we deploy AEDs I think that would help everybody. I realize this was done within Toronto and some of these findings may not be generalizable to other cities, but I think this is definitely a great way to make us reshape our thinking in terms of how we do this, and so a question I have for Tim if I may, are you aware of any similar studies that have been done looking at this in other cities and then if not, how do we encourage other groups to do similar work?
Dr. Chan: There have been similar studies done that have focused really on the spatial side of things, so doing this 100 meter radius and counting cardiac arrests that have been nearby, there's actually been fairly little work that's been done on the spatial temporal side. And a couple of exceptions that I will note that I think are important to point out is there was a very nice study that was done out of a group in Copenhagen, and they were looking at actually spatial temporal coverage, particularly the loss in coverage that you experience when you go from looking at spatial to spatial temporal. For example if you count all of the cardiac arrests that happen nearby a registered AED based only on 100 meters, and then you count the same number, but you have to now layer on top of that when the building that the AED is in is open, then you tend to get a big loss. They found quite striking numbers, I think they found a 50% loss, when you look at evenings and weekends I believe, in Copenhagen. So basically all the cardiac arrests that happened where you thought there was an AED nearby, there's actually only one in two is actually nearby and accessible when you looked into hours of operation.
And this actually comes back to the earlier question from Carolyn about how our study relates to our previous study in 2016, so we actually replicated that Copenhagen study in Toronto where we measured spatial coverage and we measured spatial temporal coverage and we measured that loss, and we found a similar loss overall, about 20%, so 1 in 5 cardiac arrests happened where there was an AED nearby, but that AED was not available because that location was closed. So that was one of the impetuses for leading us to do this study where we start to examine specifically the different location types and the specific businesses that were involved.
Dr. Lam: Wow, that's just really inspiring Tim, I mean I'm kind of thinking about the Singapore situation too and I think it's actually applicable and I would love if we had local data similar to yours, so congratulations, I really share what Sana said. Thinking though about the public health and the larger implications of what you're talking about, what do both of you think of the implications for a public commercial partnership in these things if it is coffee stores or banks that seem to be the best locations, perhaps these have implications to how the public and private should collaborate to make these things happen, what do you think?
Dr. Chan: I completely agree. These types of public private partnerships, specifically for AED deployment are not necessarily new, they already happen in some parts of the world. One of the examples I always like to bring out is if you go to Japan and they have vending machines everywhere in Japan and then you'll often run into vending machines that have an AED right in them, so one of the benefits is that first the vending machines are everywhere and second, if you're a citizen there, you probably know where the vending machines are where you travel in your day to day life and so I would say that would be a very similar thing here in North America, whether it be coffee shops or ATMs, if someone were to put me in a random part of the city and ask me, "Hey Tim, do you know where the nearest AED is?" I'd probably have a lot of trouble, but if they said could you figure out where the nearest ATM is for your bank or where the nearest Starbucks is you know, there's pretty much one on every corner. It would be much easier to identify and find, so I think there are significant benefits to partnering with these companies or these businesses that have very broad name recognition and brand recognition, are geographically well spread and located in populated areas.
I should also mention, I feel like there's a few other benefits for these types of locations, so for example for ATMs, I think there's a lot of secondary benefits, so for example, there's a built in security component, there's a video camera there, that might be able to help make sure that no one's vandalizing or stealing an AED. There's perhaps built in weather protection because there's electricity there already, so in a cold climate like Toronto where you might worry about putting an AED outside, you could have potentially a heating cabinet that would be fed by the electricity for the ATM and so on. So I think there's actually a lot of benefits if we could actually operationalize a system like this.
Dr. Lam: Sana, do you think there are some more unanswered questions?
Dr. Al-Khatib: I did want to agree with Tim on what he said, that these public private partnerships have been in place. Unfortunately we haven't been able to make much progress. As I said, I do see the results of this study as being potentially a catalyst to improve the work that we are doing and ensuring stronger partnerships and collaborations to help us achieve what we want to achieve which is basically improve the survival rate of out of hospital cardiac arrests, so I completely agree with that and I loved your idea, Tim, when you talked about now people may not recall where AEDs might be, but if you link them with teller machines or coffee shops, I think that would be much easier to remember.
You know of course there are a lot of questions that remain unanswered unfortunately. Again as was stated by Tim and his colleagues in the paper and on the call, how we can translate these findings to other locations I think is really key and then of course doing the work, meaning let's use these data to deploy more AEDs and then really looking at the impact of that. Ultimately we want to make sure that if we hypothesize that by doing this we can improve outcomes for these victims, we would want to prove that. So I think the next steps would be to see if this can be replicated in other places, but also even within Toronto, if we can accomplish some of this and then examining the impact, I think would be extremely beneficial.
Dr. Lam: Fabulous, thank you so much Sana, thank you so much Tim for sharing your thoughts today.
Listeners, you heard it right here on Circulation on the Run. Don't forget to tell all your friends about this podcast and tune in next week.
Caroline: Welcome to Circulation On The Run! Your weekly podcast, summary, and backstage pass to The Journal and it's editors. I'm Doctor Carolyn Lam, Associate Editor from the National Heart Center in Duke National University of Singapore. What does the gut microbiome have to do with Cardiovascular Disease? Well to find out you'll just have to stay tuned for our featured discussion debate. First, here's our summary of this week's journal.
The first paper seeks to answer the question "does first trimester screening modify the natural history of Congenital Heart Disease?" To answer this question Doctor Jasinskyl and colleagues from the University Hospital in Masaryk University in the Czech Republic, analyze the spectrum of congenital heart defects and outcomes of 127 fetuses diagnosed with congenital heart defects in the first trimester compared to 344 fetuses diagnosed in the second trimester screening. All of these analyzed between 2007 and 2013.
They found that the spectrum of congenital heart defects diagnosed in the first versus second trimesters differed significantly with a greater number of comorbidities, defects with univentricular outcomes, intrauterine deaths, and terminations of pregnancy in those diagnosed in the first compared to second trimester.
They further analyze 532 fetuses diagnosed with congenital heart defects in the second trimester but in an earlier period of 1996 to 2001, which is the period before first trimester screening was introduced. In this group they found significantly more cases of defects with univentricular outcomes, intrauterine deaths, and early terminations of pregnancy. In comparison to fetuses also diagnosed with congenital defects in the second trimester but in the later period of 2007 to 2013.
Thus, the authors concluded that first trimester screening had a significant impact on the spectrum of congenital heart defects and on the outcomes of pregnancies with defects diagnosed in the second trimester. Early prenatal cardiac ultrasound screening may therefore, in some countries, reduce the number of children born with severe cardiac abnormalities and associated comorbidities.
The next study sheds light on the use of intravenous recombinant tissue plasminogen activator, or "RTPA," in patients with acute ischemic stroke also receiving no wax or the newer oral anticoagulants. Doctor Sienne and colleagues from the Duke Clinical Research Institute in Durham, North Carolina use data from the American Heart Association "Get With The Guidelines" stroke registry in 42,887 ischemic stroke patients treated with RTPA at 1,289 hospitals in the United States between 2012 and 2015. They basically found no statistically significant differences in the risk of symptomatic intracranial hemorrhage between patients who were taking Noac, Warfarin, or not taking any anticoagulant before the stroke.
This largest clinical experience of stroke thrombolysis in patients receiving Noac before the strokes thus suggest that RTPA is reasonably well tolerated without prohibitive risks for adverse events amongst selected Noac treated patients. However, the authors are quick to say that their observations must be considered as preliminary due to the absence of coagulation parameters, timing of the last Noac intake, and whether or not non-specific reversal strategies may have been applied.
The next paper provides experimental evidence of the unique effects of plasminogen activation and Alpha 2 antiplasmin inactivation on the fibrinolytic system in pulmonary embolism. In this paper from Dr Sing, Hong, and Reed from the University of Tennessee Health Sciences Center in Memphis, Tennessee the authors use mouse models of experimental pulmonary emboli to show that monoclonal antibody inactivation of Alpha 2 antiplasmin, which is an endogenous inhibitor of plasmin, effectively dissolved pulmonary emboli with similar potency to high dose RTPA.
Alpha 2 antiplasmin inactivation synergize with low dose RTPA to enhance thrombus dissolution. And like RTPA, Alpha 2 antiplasmin inactivation alone or in combination with low dose RTPA, did not cause fibrinogen degradation or increased bleeding. The authors therefore concluded that Alpha 2 anti plasmin is a dominant regulator that prohibits thrombus dissolution in vivo.
Therapeutic modulation of Alpha 2 antiplasmin activity may therefore prove an effective strategy to enhance fibrinolysis without significantly increasing the bleeding risk. These results are discussed in an accompanied editorial by Doctor Yurano from Hamamatsu University School of Medicine in Japan.
More exciting experimental data in the next paper showing that novel beta arrestin signaling pathways may be viable targets in dilated cardiomyopathy. First author Doctor Reba, corresponding author Dr Solaro, and colleagues from University of Illinois at Chicago treated a dilated cardiomyopathy mouse model expressing a mutant tropomyosin for three months with either a beta-arrestins two biased ligand of the entertance and receptor or losartan and angiotensin receptor blocker as control. Treated mice showed improved cardiac structure and function associated with myofilamins that had significantly improved myofilament calcium responsiveness. Which was depressed in the untreated mice.
These functional changes were mediated through beta arrestin which may have a novel role in increasing MLC2V phosphorylation through a previously unrecognized interaction of beta arrestin localized to the sarcamore. Thus, long term beta arrestin 2 biased agnonism of the angiotensin receptor may be a viable approach to the treatment of dilated cardiomyopathy. Not only by preventing maladaptive signaling but also by improving cardiac function by altering the myofilament calcium response via beta-arrestin signaling pathways. The concept of a two in one angiotensin receptor blocker and calcium sensitizer is discussed in accompanying editorial by Doctors Wu, Ju, and Siao from Peking university in China.
The final paper asks the question "are three arterial graphs better than two coronary artery bypass grafting?" Doctor Galdino and colleagues from Weill Cornell Medicine in New York performed a meta analysis of eight propensity score matched observational studies on more than 10,000 matched patients comparing the long term outcomes coronary artery bypass grafting with the use of two verses three arterial graphs.
They found that the use of a third arterial condo et in bypass grafting is a associated with superia long term survival irrespective of sex and diabetes status and without a higher operative risk. These results therefore support a strategy of the use of a third arterial graph and really deserve confirmation in prospective randomized trials. Well, that's it for the summaries. Let's welcome our guests.
Our topic for discussion today is so exciting. In fact, I am going to read from the paper describing it as an exciting, new, and important field of investigation where we start to understand how nutrition, our gut micro-community composition, and our genetics actually all play a part in Cardiovascular Disease. And to discuss this paper I have the first and corresponding author Doctor Wilson Tang from Cleveland Clinic Foundation as well as Doctor Nikhil Munshi, Associate Editor from UT Southwestern. Welcome Wilson and Nik!
Nik: Thank you.
Wilson: Thank you.
Caroline: Wilson, please set the stage for us! What does our gut microbiome have to do with cardiovascular disease? I agree it's a hot area but, you know, could you just describe what it actually means.
Wilson: This has been somewhat of an accidental discovery from our group when we start encountering different types of metabolites that we measure to kind of associate them with Cardiovascular Disease. And unbeknownst to us, some of them are produced by the bacteria that live inside us to which we convert and try to eliminate. So one such metabolite that we identify is, which in many of the foods that we tell our patients, advise our patients that have high risk of Cardiovascular Disease. So all these connections come together to form a scientific basis to which how one of the biggest environmental exposures that we have which is what we eat every day is filtered by trillions of bacteria that live inside us and many of these metabolites become hormones that effect our every day function and activity.
And, in many ways, can actually lead to diseases that are so remote from the gut but such as Cardiovascular Disease, Atherosclerosis, and we further identify these process and they impact downstream organ function like heart function and kidney function. So these are all very excited areas and this is just one of several metabolites. There are other metabolites that also impact blood pressure and even brain function and so all these areas become kind of a new avenue for us to look at potential therapeutic targets.
Caroline: Yeah I think it's so completely fascinating that we can actually each experience a given meal differently based on the different types of gut microbial communities in our bodies isn't it? And that that actually can effect things all the way from atheroscleroses, to obesity, insulin resistance, and so on. Could you give us a specific example from your research?
Wilson: We actually identified a metabolite, a very small molecule called Trimethylamine N-oxide, we abbreviate it as TMAO. And TMAO is actually formed from the bacteria from a precursor called Trigosamine which is, you know, gas. In other words, the bacteria taken substances of nutrients such as choline and connetine which is actually common in many foods but particularly in red meats, in egg yolks, and many other foods that we know are potential contributors to Cardiovascular Disease.
And actually converted into this gaseous compound that our liver converted into a neutral compound, that we think is neutral for a long time and nitrogenous waste, except that when we have both animal studies and human studies patients with high levels of this TMAO metabolite has been associated with a high risk of Cardiovascular Disease. And in fact in animal studies we have direct evidence that show its contributing to the mechanistic compartment.
Caroline: Now extrapolating from what you just said so vegetarians, for example, or vegans even more so, would have less TMAO levels then?
Wilson: Yeah, obviously there are wide variation in these levels actually change almost by the minute because obviously we eat different times of the day and it comes in and out of our bodies. But in general, yes, in other studies that we actually identified a higher level of in carnivores which are meat eaters verses vegans and vegetarians who do not eat meat.
Wilson: Yeah and we actually use... I sort of labeled choline and connetine to actually directly show that the synthesis of TMA and TMAO by a labeled connetine is higher in meat eaters, carnivores, verses vegetarian or vegans.
Caroline: Oh, I really have to ask both you Wilson and Nik the following question then. What do you think is the, you know, take home message? How do you apply this clinically and even more cheeky, perhaps, how are you applying this in your own life? I mean with this knowledge have you become vegetarian? I'm putting you on the spot here.
Wilson: I think this is basically a very scientific demonstration of how what we eat does impact our every day bodily function. And I think many cultures have this identification. Obviously many Asian cultures have seen the impact of food. In fact, it actually opens entire insight into how different medicinal food may actively be impacting the gut microbiome that actually creates different effects in the body. But in terms of diet and nutrients, yeah I have totally have eaten less meat in my every day dietary habits.
I definitely think it's something that is certainly quite insightful and probably very impactful. That being said, I think different cultures also have different populations of microbiome and I think it's not a one size fits all. In fact I think every individual has his own dynamic ranges and we are still in the very very first early stage of understanding how this impact helps in disease. So there's a lot of excitement and there's a lot of technology that hopefully can help us to unravel this mystery.
Caroline: Exactly, a new and important field just like you said. Nik, what do you think?
Nik: From my standpoint, I'm actually not a big meat-eater so this was very welcomed news when this all came out. But, you know, from another standpoint it really opens up a lot of new questions. You know, it kind of blurs the line between sort of genetics and environmental factors. You know, so the questions of maybe a family who shares certain genetic traits may also share certain environmental traits. In other words, they share certain gut microbial components and maybe this sort of complicates how we're going to disentangle some of these risk factors going forward. I'm interested to get Wilson's take on this.
Wilson: Yeah it gives us a lot of insight to the I guess what happens is the microbiome is isolated in the family lineage because the lifestyle exposure are very similar in each household. So, what we thought is inherent is being inherited from both the genomic but also a microbiome perspective.
Caroline: Nik, you manage this paper. I really love, for example, that figure which I think everyone should get ahold of the journal and have a look at. Could you tell us a little bit more about this category of papers?
Wilson: I'm sort of charged with this task of bringing sort of basic Science across the aisle to clinicians so that we can all sort of talk the same language and perhaps interact on a higher level. And so I was really excited reading some of Wilson's work and you know I really wanted to bring that to some of our broad readership just so that we could sort of appreciate what sort of science was going and I really think that this is a really great example of something that's on the verge of being translated.
You know you can imagine that by either effecting certain metabolite compositions or maybe by treating certain subsets of bacteria we may be able to influence long term cardiovascular risks not to mention obesity, diabetes, and some of these other diseases that Wilson is actively working on. So I really read this with a lot of excitement and I wanted to bring this to a broader audience and you know we have a number of other articles that are in the pipeline that I think will serve to bridge this gap and put us on the same field so that we can kind of speak the same language.
Caroline: Wilson, did you have a good time sort of writing something like this its not long.
Wilson: It's actually very difficult. In fact, its just like writing poetry. You know it's hard to write in simple and short sentences. So it actually was a big challenge for me and I really thank the opportunity to be able to do that but I also want to emphasize I think it was a very insightful experience for me too. Because as a practicing physician and a commissioned scientist don't always merge these too few, these two areas in a way to actually see the importance we like to learn the science and try to explore I think clinicians really need to take charge and learn exciting science that's occurring. I think this is a wonderful avenue and I applaud [inaudible 00:18:10] for setting this radio [inaudible 00:18:11]
Caroline: Well listeners you heard it first here on Circulation On The Run it is poetry by Wilson Tang. So please, please pick up a copy of today's journal and don't forget to tune in again next week!
Dr. Carolyn Lam: Welcome to Circulation on the Run. Your weekly podcast summary and [inaudible 00:00:06] of the journal and its editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. In just a moment we will be discussing really fascinating preclinical data to suggest that high fiber diet and acetate supplementation may change the gut microbiota and thereby prevent the development of hypertension and heart failure. But first here's your summary of this week's issue.
The first paper describes the impact of heart transplantation on the functional status of children with end stage heart failure in the United States. First author, Dr. Peng, corresponding author Dr. Almond and colleagues from Stanford University, use the organ procurement and transplantation network to identify 1,633 US children age less than 21 years, and surviving one year or more post-heart transplant, from 2005 to 2014, with a functional status score available at three time points. Namely at listing, at transplant, and one year or more post-heart transplant. They found that at the one year assessment 64% were fully active with no limitations, or a functional status score of 10. 21% had minor limitations with strenuous activity, or a functional status score of 9. And 15% scored a functional status score lower than 9. Compared to the listing functional status, functional status at one year post-transplant increased in 91%, and declined or remain unchanged in 9%. Early rejection, older age, African-American race, chronic steroid use, hemodynamic support at heart transplantation, and being hospitalized at transplantation, were all associated with abnormal functional status post-transplant.
These findings may be helpful to patients, families, and referring providers by providing a contemporary picture of the post-heart transplant life in children as they weigh the risks and benefits of transplantation.
The next paper brings cardiac reprogramming one step closer to clinical translation. In this paper by first author Dr. Mohamed, corresponding author Dr. Srivastava, and colleagues from Gladstone Institute of Cardiovascular Disease in San Francisco, the authors used a high throughput chemical screen in post-natal mouse cardiac fibroblasts, and found that transforming growth factor beta, or TGF beta, and WNT, or wint inhibition, enhanced transcription factor based direct reprogramming of cardiac fibroblasts to induce cardiomyocyte like cells in vitro and in vivo. A combination of TGF beta and wint chemical inhibitors increased the quality, quantity, and speed of direct reprogramming, resulting in improved cardiac function after injury as early as one week after treatment. These chemical inhibitors enhanced human cardiac reprogramming and reduced the number of transcription factors needed for human cardiac reprogramming to just four factors. These findings if validated in large animals could facilitate a combined gene therapy and small molecule approach to heart failure.
The next study is the first report of the risks of cardiac mortality among five year survivors of childhood cancer beyond 50 years of age. First author Dr. Fidler, corresponding author Dr. Hawkins, and colleagues from University of Birmingham in United Kingdom, looked at the British childhood cancer survivors study, a population based cohort of 34,489 five year survivors of childhood cancer that was diagnosed from 1940 to 2006 and followed up until February 28th in 2014. The authors quantify the cardiac mortality access risk. Overall 181 cardiac deaths were observed, which was 3.4 times that expected. Survivors were two and half times more at risk of ischemic heart disease, and almost six times more at risk of cardiomyopathy or heart failure at death than expected. Among those aged over 60 years, subsequent primary neoplasms, cardiac disease, and other circulatory conditions accounted for 31%, 22%, 15% of all deaths. Specifically for cardiomyopathy or heart failure deaths, survivors diagnosed between 1980 and 1989 had 29 times the excess number of deaths observed per survivors diagnosed either before 1970 or from 1990 onwards. Thus the authors concluded that excess cardio mortality among five year survivors of childhood cancer remains increased beyond 50 years of age, and has clear messages in terms of preventative strategies. However, the fact that the risk was greatest in those diagnosed in 1980 to 1989, suggests that initiatives to reduce cardio toxicity among those treated more recently may be have a measurable impact.
The last study describes the 30 day results of the Source 3 Registry, that is the European Post Approval Registry of the latest generation of the Sapien 3 trans-catheter heart valve. Dr. Wendler and colleagues from King's Health Partners in London, describe that these 30 day results of the Source 3 Registry demonstrate that trans-catheter uratic valve implantation, or TAVI, using the Sapien 3 resulted in high procedural success with low procedural complications, and excellent post-implant hemodynamics. Moderate to severe paravalvular leakage appeared to be lower with the Sapien 3 than reported with prior versions of this trans-catheter heart valve. Rates of pacemaker implantation were higher with the Sapien 3 than in earlier generations of the valve. This, in combination with the growing experience of patient selection, procedure planning, execution, and post-operative care has led to one of the best short-term outcomes ever reported after TAVI. These results are discussed in an accompanying editorial by Dr. [Altassi 00:06:58], and Dr. [Urani 00:06:58], from the Emery Midtown Hospital in Atlanta, Georgia, where they say that these early results from Source 3 Registry are a source of encouragement with some caveats.
Well, those were your summaries. Now for our feature discussion.
I am so honored to have two lovely ladies join me today on the show. And they are the first author of a feature paper, Dr. Francine Marques from Baker Heart and Diabetes Institute in Melbourne, Australia, as well as Dr. Peipei Ping, associate editor from the David Geffen UCLA School of Medicine. Welcome ladies.
Dr. Peipei Ping: Hi, hello.
Dr. Francine Marques: Hi, thank you for having us.
Dr. Carolyn Lam: As a clinician, I have very very often advised my hypertensive patients to go on the dash diet. And you know, I have no had any trouble explaining the low salt bit, right? I understand it. But then I realize that I've always advocated as well the high fiber bit, not actually really understanding how high fiber directly impacts blood pressure. And I'm so excited because your paper, Francine, shed some light on this and it actually has something to do with the gut. So could you please explain what you did and what you found?
Dr. Francine Marques: So we fed a mouse model called [adoca 00:08:25] model of habitation, that also developed heart failure, we fed them a high fiber diet for three weeks, and then after that we did a surgery to make them become [habitant 00:08:36] safe and we followed them up for six weeks. And what we observed through that trajectory is that mice that were fed a high fiber diet had significantly lower systolic and diastolic blood pressure, and also an improvement in the heart function, and also a decrease in both heart and brainal fibrosis. And the reason why the fiber is so important is because although we usually don't digest the fiber, the bacteria in our gut absolutely love it. And that allows the bacteria, good bacteria to grow. And with that growth we have release of the fermentation of the fiber, releases in short chain fatty acid. So these specific molecules can then be put back into our body and can help us in our health. So we also fed these mice acetate, which is one of the short chain fatty acids, directly and we also observed very good improvements in blood pressure and cardiovascular health.
Dr. Carolyn Lam: It's just fascinating. So these are studies in mice. What do you think of clinical translational aspects of this?
Dr. Francine Marques: Large epidemialogical studies have shown that there is an inverse correlation between fiber consumption and blood pressure. And they have seen this through very small clinical trials looking into the intake of fiber lowering blood pressure. But our study opens the possibility of new interventions using maybe short chain fatty acids specifically, but are also looking into a different type of fiber. So most studies would look into either soluble or insoluble fiber directly. Our study, the diet that we used, is mostly resistant starches. So these are their preferred type of fiber for bacteria growth in our gut. And maybe they use a [inaudible 00:10:32] type of fibers as well could be a new [inaudible 00:10:36] opportunity.
Dr. Carolyn Lam: Peipei, I remember you discussing this paper at our editorial meetings and you so beautifully highlighted the novelty of this paper. Could you share this with our listeners?
Dr. Peipei Ping: Often within many complex studies trying to understand cellular pathways and mechanisms of cardio protection, it's a very important topic as we have had our research focus on in the pas t 25 years. What's very unique and provocative of this particular study is that it simply identified critical metabolic pathways that actually is underlying the protective effects. Many of us have wondered about with eating, for example vegetables or high fiber diet, it is examined specific molecules that have both a direct as well as an endocryne path that would circulate things back to the cardiac muscles, and having the muscles becoming more protective because of regulation of certain transcriptomic pathways to support cardiac muscle contraction. So we were very impressed by both the new concept as well as the state of the art technologies employed in this investigation.
Dr. Francine Marques: Thank you, that's very nice.
Dr. Carolyn Lam: I couldn't agree more, you put it so beautifully Peipei. I thought that it was really nice also linking pathways as well as linking several organ systems. Is there anything you might want to highlight about the renal effects, not just cardiac?
Dr. Francine Marques: Yes. Many times investigations been focusing on if something went wrong how do we cure it? More precious is when we find novel results telling us the healthy individuals, what are the things we should be doing so our blood pressure would stay at the normal level, or our cardiac function is being protected if there's an insult or injury. And so in this situation, the examination of the entire renal transcriptomic do give us very valuable information on how the blood pressure regulation system that maybe actually protected by the short chain fatty acid acetate.
Dr. Carolyn Lam: So true Francine. Anything else to add?
Dr. Francine Marques: Just to say circulation, for giving the opportunity to submit this paper, and share it with the world. We're very very excited about the data.
Dr. Carolyn Lam: Yeah we should be the ones to thank you. It's a beautiful paper. We're very privileged to publish it in circulation. May I ask what are next steps for you? What do you think needs to be done from here?
Dr. Francine Marques: We're validating this in other models now. And we're also looking into the [inaudible 00:13:57] microbiome and how that's related to habitation. So trying to really pinpoint mechanisms and how we can move this forward into the clinic.
Dr. Carolyn Lam: That's so great. And Peipei, do you think that there's certain gaps that urgently need to be addressed now?
Dr. Peipei Ping: Yes, I think one of the most beautiful thing that ... Concept, illustrated this investigation is we really couldn't be just focusing on one organ, our primary interest organ, heart, alone. What's demonstrated here is a beautiful link of both mechanism as well as governed by transforming parbolytes with endocryne effects. How the gut, the kidney, and the heart are all connected together in this process, achieving a better protective condition in the environment for the cardiac muscle.
Dr. Carolyn Lam: Thank you listeners. You've been listening to Circulation on the Run. Tune in next week for even more news.