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.
Do we finally now have a simple, evidence-based way to make a diagnosis of heart failure with preserved ejection fraction? Well, today's feature paper certainly brings us closer to that goal and you must listen to the discussion coming right up after these summaries.
Bleeding is commonly cited as a reason for stopping oral anti-coagulants. However, what is the prognostic significance of minor bleeding events, or so called nuisance bleeding, in patients with atrial fibrillation on oral anti-coagulants?
First and corresponding author, Dr O'Brien from Duke Clinical Research Institute and her colleagues, identified 6771 patients with atrial fibrillation in the Orbit AF Prospective Outpatient Registry. They ascertained nuisance bleeding from medical records defined as minor bleeding that did not require medical attention. Overall, 20% had documented nuisance bleeding giving an incidence rate of 14.8 events per hundred person years. Nuisance bleeding was not associated with a higher risk of major bleeding, or a stroke and systemic embolism over the next six months.
These findings therefore suggest that the occurrence of nuisance bleeding or minor bleeding should not lead to changes in anti-coagulant treatment strategies in patients treated with anti-coagulants.
The next study sheds new light on mechanisms linking NLRP3 inflammasome activation to atherogenesis. Dr Westerterp from Columbia University, New York and colleagues studied mice with myeloid deficiency of ATP binding cassette transporters A1 and G1 and concomitant deficiency of the inflammasome components NLRP3 or caspase-111.
They showed that cholesterol accumulation in myeloid cells activated the NLRP3 inflammasome. NLRP3 inflammasome activation enhanced neutrophil accumulation and neutrophil extracellular trap formation in atherosclerotic plaques thus accelerating atherogenesis.
Patients with Tangier's disease, who had ATP binding at transporter A1 loss of function, had increased myeloid cholesterol content and showed markers of inflammasome activation. Thus, inflammasome activation may underline cardiovascular disease in these patients.
The next study identifies TPX20 as a novel transcription factor regulating angiogenesis. TPX20 is a crucial transcription factor for embryonic development and its deficiency is associated with congenital heart disease. However, its role in angiogenesis has been not been previously described. At least until today's paper from co-first authors Dr Meng and Dr Gu and co-corresponding authors Dr Cooke and Dr Fang from Houston Methodist Research Institute.
These authors use loss and gain function approaches to explore the role of TPX20 in angiogenesis both in vitro and in vivo. They showed that with VEGF stimulation, the transcription factor TPX20 upregulated PROK2 with is secreted from endothelial cells and gauges its receptor PROKR1 and thereby promotes angiogenesis in autocrine manner.
This novel signaling pathway appeared to be highly conserved as it functioned in zebra fish vascular development and the angiogenic response to ischemia in a mouse model of peripheral disease. The authors furthered showed the selective role of TPX20 in endothelial migration but not proliferation. Furthermore, treatment with recombinant PROK2 the critical effector of TPX20, improved blood profusion and functional recovery in the mouse peripheral artery disease model. Thus, these data highlight the therapeutic potential of PROK2 in augmenting functional angiogenesis for diseases associated with this regulated angiogenesis.
In patients with atrial fibrillation, left atrial appendage closure with the Watchman device, is known to prevent thromboembolism from the left atrial appendage. However, thrombus may still form on the left atrial face of the device, which then may potentially embolize. This next paper provides important data on the incidents, predictors, and clinical outcomes of device-related thrombus after left atrial appendage closure.
First author, Dr Dukkipati and corresponding author Dr Reddy from Icahn School of Medicine at Mount Sinai, New York and their colleagues studied the device arms of 4 prospective FDA trials of patients undergoing the Watchman implantation. These were the PROTECT AF, PREVAIL, CAP, and CAP2 trials.
They found that following percutaneous left atrial appendage closure with the watchman device, the incidence of device-related thrombus was 3.7% and this was associated with a more threefold higher risk of stroke and systemic embolism. Predictors of device-related thrombus were a history of trans- ischemic attack or stroke, permanent atrial fibrillation, vascular disease, a larger left atrial appendage diameter, and a lower left ventricular ejection fraction.
Device-related thrombus was not associated with an increased risk of cardiovascular or all-cause mortality. Nearly 75% of patients that developed device-related thrombus did not experience a stroke. And ischemic strokes occurring in patients with device-related thrombus accounted for approximately 10% of all ischemic strokes, following left atrial appendage closure. Thus, given the ramifications of device-related thrombus, a judicious surveillance strategy using periodic transesophageal echo cardiography may be considered particularly when risk factors for device-related thrombus are present.
Well, that wraps it up for our summaries. Now for our feature discussion.
Heart failure with preserved ejection fraction or HFpEF, notoriously difficult diagnosis to make, but do we finally have a validated diagnostic algorithm for HFpEF? Oh, you have to listen to our conversation today. I am so proud and pleased and thrilled frankly to have with me today the corresponding author of the feature paper, and that's Dr Barry Borlaugug from Mayo Clinic in Rochester, Minnesota as well as editorialist Dr Walter Paulusus from VU University Medical Center in Amsterdam.
Thank you so much both of you for making it here. I want to dive straight into it. So, Walter, maybe could you please paint the background to this because you wrote I think the most highly cited diagnostic guidelines of HFpEF, but that was in 2007. Tell us how does today's paper take us forward?
Dr Walter Paulus: Thank you very much, Carolyn. It's quite an honor for me to give you comments about this paper, which I think is going to be a landmark event. Over the years we have seen multiple algorithms being proposed usually by professional societies like V and C or the American Society of Echocardiography for the diagnosis of HFpEF. The major drawback of all these algorithms is that they have never been validated in clinical practice. And the reason they have never been validated was that it was extremely difficult to establish a gold standard for HFpEF.
And Barry was so clever to already invest in an establishing a gold standard for HFpEF ten years ago, and he very vigorously subjected all his patients in whom he suspected HFpEF to an invasive stress test and could establish the diagonals of HFpEF using this as a gold standard. And then he used all these consecutive patients with subsequently used to devise some form of an algorithm that was immediately validated against a gold standard. I think this has been a giant leap forwards. And again, I want to congratulate him with this unique endeavor.
Dr Carolyn Lam: Barry, I want to echo Walter's words and congratulate you. Now, has it really been ten years in the making? Tell us about this, Barry.
Dr Barry Borlaug: It has. In fact, it was 12 years ago when we started doing this, in 2006. But, yeah, these patients were examined in our laboratory between 2006 when I joined the staff at the Mayo Clinic to 2016. And really just doing this work up, we kind of started out doing it on a few patients and then we realized how powerful the methodology was. We did the invasive exercise testing with hemodynamics and a larger number of patients and just through accumulating a large number, as Walter points out, with a gold standard assessment this allowed us to then determine which less invasive attributes could be used to identify the likelihood that heart failure was the diagnosis.
Dr Carolyn Lam: That's so great. But you know beyond just that it is such a precious data set and so on, your paper is just so beautifully written and so clinically applicable. You've got this HFpEF score now for diagnosis. Everybody's going to be talking about it. So tell us about it. What does HFpEF score? What makes you think it'll work? How do you apply it clinically?
Dr Barry Borlaug: Thinking about diagnosis a lot, you really have to go back to [00:19:19] thinking, estimating the probability of disease, and when you're able to do that then you can find people where you need to perform really more invasive testing like the exercise testing. So really, we started like we need to have a better way to define who needs that more expensive and invasive evaluation. So we have this large cohort of patients, over 500 patients, 414 in the initial cohort, and then another 100 in the validation cohort. And they had all undergone this work up, they'd all undergone very detailed clinical evaluation and pheno typing. And we hypothesized which characteristics we thought would be most relevant. And then we did logistic regression to identify all the predictors.
There were many things that are associated that you would expect with HFpEF, but there were only 6 factors in the end in a multi-variable model that were all independently associated. That provided the most parsimonious sort of model or score that we could develop. We included these six different variables. So there's two for letter H- heavy and hypertensive, and by heavy we define that as a body mass index above 30. Hypertensive is defined as two or more antihypertensive medicines. The F in the H2 HFpEF score is atrial fibrillation, either paroxysmal or persistence a. Fib. The P is for pulmonary hypertension as estimated by echo with an estimated PA systolic pressure on echocardiography of 35. We wanted all of these to be noninvasive criteria for this score. E is for elder. I specifically didn't call it elderly because that can be a pejorative term and its only 60 years which is not that old. So E is elder. And F is for filling pressures, again estimated by echo doppler cardiography as an EE prime ratio greater than 9.
All of the scores are not one point each. They were arranged based on the strength of correlation in the logistic model. So being obese, having a BMI above 30 was awarded two points because it has a strong correlation. Being in atrial fibrillation or having a history of atrial fibrillation was even stronger at three points. If you tally these up, the score can range from 0-9, and based on that score you can then estimate a probability that HFpEF is present, if you're evaluating a patient that meets the entry criteria of the study, which is basically normal ejection fraction, and exertional breathlessness.
Dr Carolyn Lam: Nice. Okay, Walter, I think I can safely say that you have been thinking about this syndrome longer than either Barry or I. So I'd love your perspectives on how do you think this will be put into practice clinically perhaps, and where is the key area that it will change practice compared to perhaps the old diagnostic algorithms were like?
Dr Walter Paulus: I think this is a very important point, Carolyn. I think this score is so easy to handle and it is so well validated that we can now go to general practitioners and cause a general awareness for the disease. What vies me is that many patients are still unreported. The reason is that general practitioners and even general internal medicine people do not realize the [00:19:19] heart failure with preserved ejection fraction. Now with this score at hand, we can convince them that there needs to be an awareness when they see people that have value higher than six on the score, that they should be suspicious of heart failure being part of the symptomatology. I think this score mainly has its usefulness for general practitioners and general internal medicine.
Apart from the score, and it's more up to Barry to comment on this, but I want to highlight also, that he did not only develop the score, but he also had these very beautiful nomograms which is more of a find than a score, where he treated the variables in a continuous way. I think this is fairly useful for cardiologists and especially for people who want to have acute patients into trials because here we now have a very refined scale that goes from 0-160 and that allows you again to see what type of population you are addressing, what type of patients you are seeing that eventually what type of patients you are recruiting. I think for me the HFpEF score is of importance for general practitioners, general internal medicine, and especially I think we should also promote the nomogram. The nomogram, I think, are so refined that it would be useful tool, I think an excellent tool, for includement into trials.
Dr Carolyn Lam: Oh wonderful. Both of the simplicity and the cleverness, if I may, of this paper are precious to generalists and cardiologists. But Barry, I do have a couple of questions for you. Both you derivation and validation were in Olmsted if I'm not wrong. Now how am I supposed to apply it to my skinny HFpEF patients in Asia or elsewhere?
Dr Barry Borlaug: That's an important point, Carolyn. And it's a limitation of the paper. The people in Olmsted County, MN are not the same as they are in other parts of the United States or other parts of the world. I think that additional evaluation and other cohorts are important. We did the best we could with what we had. We did look at the patients carefully at Mayo Clinic. People think of it as quaternary referral center, but a pretty substantial number of the patients are from the local area, I think about 2/3 of them were. And when we looked in a subset in a sensitivity analysis of the people that were more local practice rather than coming from large academic medical centers, the HFpEF score, or as Walter pointed out, the continuous HFpEF model performed equally well. When we looked at people with so-called advanced HFpEF so high hemopressures at rest versus people at so called early stage HFpEF the people that have normal hemodynamics at rest but elevation during exercise. The model also worked well in that cohort.
But, like most studies that come out of where I work in southeastern Minnesota, it is mostly Caucasian people, the mean BMI was in the low 30s. So we need to look at other populations to make sure this works elsewhere as well.
Dr Carolyn Lam: Barry, let it go on record that I am your biggest fan. So thank you so much for this. I was just thinking even in other populations where the mean BMI may be lower for example here in Asia, we still definitely see an association with a higher BMI albeit at a lower cutoff with the presence of HFpEF. So it does raise this issue of do we need to maybe calibrate the score differently in different geographies or ethnicities. But that's not by any way take away from the tremendous input that you've made.
One other question is also the strength of atrial fibrillation in impacting the score. What are your thoughts on the possibility of misdiagnosis for example atrial fibrillation as HFpEF or the similar situation since they share symptomatology?
Dr Barry Borlaug: This is a great point, Carolyn. People still sort of argue about this. Somebody has breathlessness and effort intolerance and atrial fibrillation. Some doctors say they have symptomatic atrial fibrillation, but when we put catheters when we take these patients to the so-called table of truth and put catheters in and exercise them, we see hemodynamic arrangements that are diagnostic of heart failure. This led us to believe that this isn't just symptomatic a fib. It's really HFpEF. And that's why they have a fib. We published a paper earlier this year in circulation, more of a brief report, on the association between atrial fibrillation and HFpEF where we first reported this. That if you have normal EF, and especially permanent atrial fibrillation, you can pretty much take it to the bank that the patient probably does have heart failure with preserved ejection fraction, at least in the way that we have sort of defined it and the way that [00:19:19] initially defined it as an inability of the heart to pump blood adequately at normal filling pressures.
These patients almost all have that criteria for cardiac failure. I think that it is a really strong indicator and we probably are really just like in the general clinics, under recognizing HFpEF. I think probably in other clinics where people have atrial fibrillation and effort intolerance, we're again really under recognizing HFpEF in these people.
Dr Carolyn Lam: Indeed, and it's actually very consistent with Walter, your recommendations where atrial fibrillation played a big part too. Do you have any thoughts or advice?
Dr Walter Paulus: My idea is that atrial fibrillation and HFpEF are both manifestations of the same underlying process, which is systemic inflammation because of a metabolic disturbance. We used to think of atrial fibrillation as a consequence of left atrial dilatation, which itself was caused by the high filling pressures. I think that this does not hold, there is more to it. I think the atrium is as sick as the left ventricle and it undergoes similar pathological changes. That's why the presence of a fib becomes such a strong determinant of the presence of HFpEF in Barry's H of HFpEF score. All of this makes a lot of sense to me.
I just want to add something else. You spoke about the Asian population having less BMI and already having HFpEF. I think if you look at Barry's variables in uni-variant analysis, there's one which was presence of diabetes or prediabetes which did not make it in the multi-variant analysis on 0.06. It's my belief that if you got to the Asian population, that probably the BMI could be replaced with the presence of prediabetes and diabetes. Usually the insulin tolerance or insulin resistance is presence and the BMI is still low. I think there is need for some fine tuning, maybe in Asian populations, and I think this should be a challenge to go ahead with it. In fact, I'm leaving for Japan the day after tomorrow and I'm going to show the slides of Barry's paper. I'm going to try to set something up to also validate the score in Japanese populations.
Dr Carolyn Lam: We've got our work cut out for us, Barry! Let's get on to this too in southeast Asia.
Dr Barry Borlaug: I totally agree with Walter. I think that's great. And Carolyn, you, in a lot of papers, point this out, that the metabolic, cardio-metabolic associated with excess body mass, the way we define it with BMI, is shifted way down in southeast Asian population, and south Asian population, so I would agree with Walter's hypothesis that diabetes, prediabetes maybe that's the better way to go when we look at this in other patient populations.
Dr Carolyn Lam: You both absolutely made my day with this discussion today. Thank you so much. What a thrill to be on the same podcast with the people I admire most.
Listeners, I know you enjoyed this as much 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 it's editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
Can we get better at predicting clinical benefit of PCSK9 inhibition based on the severity and extent of coronary artery disease? Well coming right up after these summaries we have an important discussion of an analysis from the FOURIER trial, so stay tuned.
The first original paper this week suggests that targeting visceral adiposity may be the crucial step to limit age-related cardiac remodeling and to promote healthy cardiac aging. Co-first authors Drs Sawaki and Czibik, corresponding author Dr Derumeaux, from INSERM France, and their colleagues, hypothesize that since aging induces cardiac structural and functional changes, linked to increase deposition of extracellular matrix proteins including osteopontin, well osteopontin may play a role in myocardial aging.
To test this hypothesis, they studied osteopontin-deficient mice and their wild-type litter mates at two and 14 months of age in terms of cardiac structure, function, histology and key molecular markers. They found that during aging, visceral adipose tissue represented the main source of ostepontin and altered heart structure and function via its profibrotic secretome. Furthermore, interventions targeting osteopontin, such as visceral adipose tissue removal and osteopontin deficiency, rescued the heart and induced a selective modulation of fibroblast senescence. This work uncovers ostepontin's role in the context of myocardial aging and suggests that osteopontin may be a potential new therapeutic target for a healthy cardiac aging.
The next study shows that higher triglyceride rich lipoprotein cholesterol may be a risk factor for cardiovascular disease and potential therapeutic target. First author Dr Vallejo-Vaz, corresponding author Dr Ray from Imperial College London, and their colleagues assess the relationship between triglyceride-rich lipoprotein cholesterol and cardiovascular risk and whether this risk was modifiable among patients receiving statins in the TNT trial. They found that higher levels of triglyceride rich lipoprotein cholesterol were associated with a significantly higher rate of cardiovascular events among coronary patients treated with statins. Statin therapy reduced triglyceride-rich lipoprotein cholesterol and to a greater extent among those treated with a higher statin dose.
Based on their post hoc analysis of the TNT trial, they found that more intensive statin therapy with atorvastatin 80 milligrams, compared to atorvastatin 10 milligrams, resulted in a significantly greater cardiovascular risk reduction among patients with higher triglyceride-rich lipoprotein cholesterol. These results were consistent for higher triglycerides and directionally concordant for non-HDL cholesterol. A higher percentage reduction in triglyceride-rich lipoprotein cholesterol was associated with lower cardiovascular risk independent of LDL cholesterol reduction. Thus, these findings suggest that triglyceride-rich lipoprotein cholesterol is not only a cardiovascular risk marker, but also potentially a therapeutic target.
Late gadolinium enhancement on cardiac magnetic resonance imaging represents fibrosis and is seen in 60% of adult patients with hypertrophic cardiomyopathy. However, what about in children and adolescents with hypertrophic cardiomyopathy? First author Dr Raja from University of Copenhagen in Denmark, corresponding author Dr Ho from Brigham and Women's Hospital in Boston, and their colleagues looked at cardiac magnetic imaging data from 195 children and adolescents with hypertrophic cardiomyopathy. Late gadolinium enhancement was present in 46% of patients with overt hypertrophy as opposed to 60% typically represented in an adult population of hypertrophic cardiomyopathy. On the other hand, late gadolinium enhancement was not seen in mutation carriers without left ventricular hypertrophy.
In patients who underwent serial imaging, increases in late gadolinium enhancement, left ventricular mass, and left atrial size were detected over two and a half years. Thus these findings in children provide additional insights into the biology and natural history of hypertrophic cardiomyopathy and confirmed that fibrosis is a significant part of the disease process in both children and adults.
Whether the adult mammalian heart harbors cardiac stem cells for the regeneration of cardiomyocytes is an important yet contentious topic in the field of cardiovascular regeneration. This week's paper adds to the growing knowledge in this area. First author Dr Li, corresponding author Dr Zhou from Chinese Academy of Sciences and their colleagues developed a new genetic lineage tracing system to label all nonmyocyte populations that contain putative cardiac stem cells. Using dual lineage tracing system, they assessed if non-myocytes generated any new myocytes during embryonic development, adult homeostasis and after myocardial infarction. Skeletal muscles were also examined after injury and acted as internal controls.
By using this stem cell marker free and dual recombinases mediated cell tracking approach, the author showed that new myocytes arose from nonmyocytes in the embryonic heart, but not in the adult heart during homeostasis or after myocardial infarction. As positive controls, the same lineage tracing system detected new myocytes derived from nonmyocytes in the skeletal muscle after injury. Thus, this study provides in vivo genetic evidence for non-myocyte to myocyte conversion in the embryonic but not the adult heart. This study also provides a new genetic strategy to identify endogenous stem cells, if any, in other organ systems for tissue repair and regeneration.
Well, that wraps it up for our summaries this week, now for our feature discussion.
Are there subsets of patients that derive greater clinical risk reduction with the PCSK9 inhibitors? Well we're gonna find out about that right now with a discussion of our feature paper entitled the “Clinical Benefit of Evolocumab by Severity and Extent of Coronary Artery Disease.” So pleased to have with us Dr Marc Sabatine from the TIMI Study Group, who is the first and corresponding author of today's feature paper, as well as our editorialist, Dr Roger Blumenthal from Johns Hopkins University. And of course, we have a familiar voice, a very important editor of our digital strategies and that's Dr Amit Khera from UT Southwestern.
Welcome everyone, I think I'd really like to start with maybe asking Roger to paint the background of the importance of this paper. Simply because I just love the title of your editorial, which is “Realizing the Value of PCSK9 Inhibitors: Are We Closer to Finding the Sweet Spot?” I think that really encapsulates it. So Roger, your thoughts?
Dr Roger Blumenthal: As Amit Khera knows, I'm a golfer, so when you think about the sweet spot on the club, and we know that PCSK9 inhibitors are a great story of translation from bench to bedside, and we also know that the high cost of the therapy presents a challenge. So what Dr Sabatine and colleagues did was to try to identify the sweet spot for its most effective use and that was a pleasure to comment on Dr Sabatine's excellent study.
Dr Marc Sabatine: I think taking a step back I would say from pure biologic perspective, we know that lowering LDL cholesterol will reduce events and that's true and primary and secondary prevention and so if you have therapies that were safe and inexpensive, then I think you wouldn't need to really look for that sweet spot cause it would be all sweet if you will to extend the analogy. But Roger's absolutely right that when you have therapies that are then expensive, then you have to decide, okay in which patients will I get the biggest bang for my buck? And that's a very legitimate question to ask.
And so in FOURIER, overall the trial was positive but as we look for subgroups we say, "Can we find individuals who enjoy a greater absolute risk reduction?" Because therefore the benefit cost ratio is gonna be particularly favorable. And so we approach that in a couple different ways. First you can look for just predictors of baseline risk, so if someone has twice the baseline risk and the same relative risk reduction, you should get about twice the absolute risk reduction and therefore the number needed to treat would be cut in half. And so based on our experience from other TIMI trials and other datasets, we looked at three features that have identified patients with higher baseline risks.
Amongst those with a history of MI which is in and of itself a heterogeneous group. And so those features were patients with a more recent MI, those with multiple prior MIs and those with known residual multivessel coronary disease. And all three features in the FOURIER dataset, not surprisingly, were predictors of risk with patients having an average about a 50% higher baseline risk. But what was particularly nice was that the subgroups also identified patients who had greater relative risk reduction. And so when you couple the two, the higher baseline risk with the greater relative risk reduction, that translated into greater absolute risk reduction then in each of these high-risk groups, the absolute risk reductions over three years or for CV death, MI, and stroke was around 3% versus around 1% for the low-risk groups.
And so that changes the number needed to treat by a factor of three.
Dr Carolyn Lam: Wow, that's so cool. Amit, do you think you could just give us a sneak peek into the editors’ discussions when you saw this paper?
Dr Amit Khera: This was an easy one, it's clearly a very important paper and if you step back 10,000-foot view, these drugs were initially approved based on LDL lowering and people were using them without knowledge of whether or not they actually lowered events. Marc's group and others have now shown us that certainly they do lower events, but really the next most important thing is application. Who should we use them in and when should they be used and where might they be most effective and I think it was said out in the introduction of this paper, this idea of personalized medicine. And I think this really is an important step forward, not just for PCSK9 field but in general, how we should be thinking about drugs, about balancing cost and benefits and who would benefit most.
So maybe one analogy, I think PCSK9 was not prescribed as much as they had been predicted given costs and other considerations and maybe with analysis like this they've hit it out of the rough back on the fairway, I threw that in for you, Roger. And I do have one question for Marc, which is this is clearly important to better define who would benefit the most and I guess in terms of action abilities, the goal here to provide guidance for clinicians where, you know, if I'm seeing a patient this morning I would take this into account or is this something larger where we recently saw with alirocumab, they changed pricing based on sub-group analysis of a higher risk group. How do you think we should move forward with this type of information?
Dr Marc Sabatine: I’ll get back to the point I raised earlier, I do want to underscore that I think that the true biologic notion is that all these patients, sub-types of secondary prevention or primary prevention all benefit from LDL lowering. So I wouldn't want people to walk out with the notion that it's the only subset that would benefit and really from a population level, obviously Roger's in a better position to speak about this, but sort of shifting the population LDL lower in general would have a huge impact on the risk for cardiovascular disease. But to your question Amit, looking in for a patient in front of you, I think it's quite fair to say right now there's this kind of tug of war back and forth between payers and clinicians.
Clinicians saying, "I have a patient in front of me, they have known atherosclerotic cardiovascular disease, I wanna lower their risk, I wanna manage their risk factors and I wanna get their LDL cholesterol lower and I have a bunch of great tools in front of me." Statin for sure is the foundation, maybe acetamide and PCSK9 inhibitors. And then payers saying, "Well wait a minute, these are expensive drugs and so we're gonna try to restrict that and create a lot of hoops for clinicians to jump through." And so I would rather than wasting all that time back and forth, I think it is logical to say, "What are the high-risk groups?" Where we can agree there's the large enough absolute risk reduction that for a given cost, that makes sense.
Allow there to be alignment for that and have clinicians just be able to write a script and have it filled rather than wasting a lot of time with preauthorization and letters back and forth.
Dr Amit Khera: That's a great point, maybe I'll just take one follow-up, which is now trying to sift through all the high-risk groups and they end up maybe becoming a bit of a Venn diagram. I know in Roger's editorial he talked about the other FOURIER analysis with PAD and there's more groups to come or do we have enough of a starting place where we think we have enough for decision making?
Dr Marc Sabatine: I would say there are a variety of groups, there is some overlapping even in the paper then we looked at the union of those three high-risk features, which identified about two thirds of the patients who were enrolled in the trial with a history of MI. But you're right, the other slices of the data that will also identify high risk groups, PAD is a particularly good one because most of the therapy for those patients has focused on antithrombotic therapy, which always will have some downside for increased bleeding, whereas risk factor modification in this case has no downside. So that's a very high-risk group, it certainly is important to focus on. But I think within the MI subset, this is a great place to start the other analyses we're doing.
And probably after we've sort of finished the series of, if you will, these kind of univariant slices, then we'll try to put that together into a more comprehensive picture.
Dr Roger Blumenthal: We tried to say that we still need the formal cost-effective analyses in these specific high-risk groups, but it seems most reasonable to focus on engaging in shared decision making now with our patients about PCSK9 inhibitor use and those with a recent ACS and the basis of Odyssey Outcomes and we're awaiting the final publication of that. Symptomatic peripheral arterial disease, which Marc previously published in Circulation, and then looking at these high-risk features that was the subject of this article, those with a more recent MI within the past two years, multiple prior MIs and residual multivessel coronary disease.
And one of the things that we especially found interesting was among the more than 8,000 individuals without a high-risk feature, the event rates were nearly unchanged in the evolocumab versus placebo groups. So I think that's very important, but one other point that we have to keep in mind is that the focus of the last set of guidelines and probably the next cholesterol guidelines that likely will be out in November, will have a large component of the shared decision making and we need to see where the cost comes down, whether these companies that make these medications will be able to significantly lower the cost in a reproduceable manner and patients and clinicians will have to jointly decide what to do, do we add acetamide? Do we add a PCSK9 inhibitor?
But we finished our editorial saying that all clinicians and patients should currently pursue a comprehensive lifestyle and medical regimen for secondary prevention. We all have to remember that and if a person's LDL, a high-risk individual is at least 70 with high-risk features and certainly above 100 on maximum tolerated statin therapy, it's important to strongly consider a PCSK9 inhibition and it'll be very interesting to see what the final wording is when the ACC/AHA cholesterol guidelines come out in November.
Dr Carolyn Lam: Amit, would you like to add any further take-home for the clinicians listening in?
Dr Amit Khera: I just first want to congratulate both of these discussions today, I think the paper was so incredibly important and I think Roger's group really helped frame it well in the field. The one thing I'd say is this is a moving target, we have some early guidance now that I do think is actionable, so I actually have clinic in about an hour and I'm sure I'll be thinking about this as I think about how to apply PCSK9. Which groups might benefit most, so I do think this is actionable now, I think the points that were made about cost effective analysis, how do we bundle all these concepts or high risk patients into maybe an algorithm and how do the guidelines interpret this as a moving target. We'll wait to see, but I do think there's some important actionable information even now for our clinical patients.
Dr Carolyn Lam: I just love that, and you know that is just so much in line with the ethos of what Circulation is about now. We really, really love the papers that you have to pick up because they're of immediate applicability to your clinical practice.
Well audience, you heard it right here. Thank you so much for joining us this week and of course 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. I'm the one you usually hear chatting about all the papers in your weekly issue, however I am so delighted to be handing over the mic this week to two beloved colleagues, and they are Dr Greg Hundley and Dr Vlad Zaha, who will be taking us through this week's very special issue centered around cardio-oncology. Here they are.
Dr Greg Hundley: My name is Greg Hundley. I'm a professor at VCU Health Sciences in Richmond, Virginia. We also have Vlad Zaha, who is an assistant professor at University of Texas Southwestern in Dallas.
Dr Vlad Zaha: Hello, everybody.
Dr Greg Hundley: We're going to be talking about the field of cardio-oncology today. As we all know, there have been many advances in the treatment of cancer lately, such that cancer is now becoming in some regards almost a manageable disease or a chronic disease for many individuals. But unfortunately we're seeing the emergence of cardiovascular disease in many patients, so much so that for some cancers, for example breast cancer survivors, cardiovascular events have supplanted the occurrence of cancer-related morbidity and mortality overall.
And so emerging today is this new field of cardio-oncology, which is really a bridging discipline between oncologists and cardiologists that have been focused almost on examining the relationship between chemotherapies, radiation therapies, newer targeted immunologic therapies on the development of cardiovascular events. We as cardiovascular medicine specialists often become involved and then we are consulted to see a patient that might be scheduled to receive a cardiotoxic therapy and what should we do. Maybe they've already received, they're in the middle of the therapy, and we're asked to provide guidance to help the patient move through that therapy successfully.
We're examining survivors now, those that have gone on the therapy and are experiencing increased cardiovascular risk. And then finally, a new emerging field that examines the association of risk factors that seem to be common between cancer and cardiovascular disease.
In this issue of Circulation there are theories, really a miniseries of manuscripts, that are at this interface between cardiovascular and oncologic science and medicine. Following a similar miniseries that we published in 2015, this new block of manuscripts looks on some of the risk factors and mechanisms that may be common between these disorders.
We're going to start today and look at this particular issue and examine the original manuscripts, look at the letters, and then talk a little bit about the review articles. I will walk through some of the introduction and then Vlad Zaha, who is working in cardio-oncology at University of Texas Southwestern, will help interpret for us some of the results and the meaning.
The first study, an original manuscript by Simes et. al that's a subanalysis of the lipid study, and that's the Long-Term Intervention with Pravastatin in Ischemic Disease. The study is going to examine the relationship between D-dimer and the future development of cardiovascular events, but also importantly, cancer-related events. Remember, D-dimer is the degradation product of cross-linked fibrin markers of hypercoagulation and thrombosis. We use this a lot in the emergency department as an identifier of those at risk when we're suspecting one of CVT, pulmonary emboli, etc.
This particular study focused on individuals aged 31 to 75 years that had experienced previously a myocardial infarction. The patients were randomized to receive 40 mg of pravastatin versus a placebo and as part of the study they were followed for six years to identify cardiovascular events. But at the end of the study another examination, an extended review, was enabled so that the patients or participants could be followed for another ten more years and in addition to looking at cardiovascular events, they also looked at all-cause mortality and etiologies of that mortality and specifically cancer.
Vlad, can you tell us a little bit about some of the results and what did D-dimer predict?
Dr Vlad Zaha: D-dimer has been considered a rather non-specific product that was first introduced in clinical practice in the 1970s for diagnosis of venous thromboembolisms. It is really interesting in this study that the others identified D-dimer that it is an independent predictor of not only long-term risk of arterial and venous events but all-cause mortality, cardiovascular disease mortality, cancer incidents and mortality and non-cardiovascular disease and non-cancer morality.
It raises interesting questions that are further explored in an editorial in the same issue about what is a low and what is a high D-dimer and also what drives the D-dimer generation in these patients.
Dr Greg Hundley: And so, it's interesting as well that one is identifying those at risk of cardiovascular disease but also cancer. Do the authors and the editorialists speculate on what that connection may be?
Dr Vlad Zaha: The question that is discussed is a common area of etiology that is being more and more discussed nowadays as bridging the domains of heart disease and cancer, and that is information. Information resulting then in alteration of the clotting cascade and hypercoagulability that may then influence downstream both atherosclerosis and cancer processes.
Dr Greg Hundley: Very good. It's interesting that we're bringing up this whole area of thrombosis because that really follows in the next study, which is a large population cohort assessment that is collected from a Danish registry of 6600 subjects that had experienced a lower extremity arterial, not venous, but arterial thrombosis. In that study what did they uncover, Vlad, in terms of an association with cancer and previously experiencing a lower extremity arterial thrombosis?
Dr Vlad Zaha: Another interesting study where the patients uncovered an increased risk of cancer compared to the general population, especially during the first six months before, the investigators identified an association between lower limb arterial thrombosis and increased all-cause mortality in common especially for the smoking-related cancers. This is a very interesting study that brings up the possibility of opportunistic screening, again focused on cancer-related signs and symptoms during the diagnostic workup for lower limb arterial thrombosis.
Dr Greg Hundley: And so, in these first two studies, both large in number, were identifying issues related to thromboembolic events and cardiovascular disease that also appear related or associated with the future development of cancer. The next couple of studies now switch and address issues related to mechanism. The first is a relatively large complex translational study by Meijers and associates that were examining the relationships between heart and vascular injury and the future development of colon cancer.
In this particular study there were two separate experiments, one group performed in mice and the other performed in analyses of serum and plasma that were collected from human subjects that had experienced colon cancer. In the first series of experiments in mice, the mice were induced myocardial infarction and then they were a strain that were somewhat predisposed to development of colon cancer. What the investigators did is they examined in this strain predisposed to the development of colon cancer, the impact of inducing a myocardial infarction and promoting heart failure versus those that were not and they identified what looks to be some sort of association between an increased risk of development of colon cancer.
Vlad, what were your observations and thoughts in terms of these particular findings and results?
Dr Vlad Zaha: This is an interesting paradigm of bringing basic science observations and testing them in a translational fashion. It is a combination of really elegant studies in a mouse model that identifies potential targets of clinical relevance in a model of myocardial infarction. The authors evaluate the fact that such molecules in human cell line models and test the proliferation in that environment. The question is then: How does this reflect in a cohort of patients? That, I think, is really the strength of the study to be able to show that some of the biomarkers identified which events can have an implication at the bedside.
Dr Greg Hundley: It was really interesting in that in the animals, independent of the hemodynamic compromise, so the hypotension, the reductions in EF, these circulating biomarkers that you identified seemed more associated with the development of colon cancer and then in the human study, examining similar factors were observed in patients with colon cancer and heart failure from the circulating blood of those individuals. Very interesting relationship identified in a very elegant translational study that involved both animal models and human subjects.
The second mechanistic paper is by Li and associates and it's really addressing the issue of anthracycline-related cardiovascular injury. Remember, we still utilize anthracycline chemotherapy today as a fundamental curative component of the therapeutic regimen for lymphoma, leukemia and sarcoma, also in those with triple-negative breast cancer as an important component of that regimen for adjuvant treatment. In this particular study, the investigators were examining the implication of phosphoinositide 3-kinase. That is an important enzymatic regulator of tumorigenesis, but it also when it's expressed is up-regulated during cardiac stress and really impacts adverse remodeling and promotion of heart failure.
In this particular study, the investigators in a mouse model were looking at blocking this particular enzyme and they had some really interesting results pertaining to the development of heart failure and cancer. Vlad, what did you see in this study that looked unique in that perspective?
Dr Vlad Zaha: This is an especially interesting study for the perspective of the oncologists who still have to prescribe anthracycline, given the uncertainty of early toxicity that can manifest in some studies in five to ten percent of patients. Also, related to the late toxicity of anthracycline treatment in survivors of childhood cancer. What is particularly interesting about this isoform of phosphoinositide 3-kinase, the gamma isoforms, is that at the same time blocking this enzyme in macrophages increases the anti-tumor, I think it's the anthracycline therapy, and blocking it in the cardiomyocytes, suggests a potential cardioprotective mechanism.
Having a target that can be used both to enhance the anti-cancer effect of anthracycline and to enhance the cardioprotective mechanism is really a potential ideal intervention that would help maximize the anti-cancer treatment and at the same time protect the heart.
Dr Greg Hundley: Fantastic. Again, new research helping to come up with ways for those that continue to need anthracycline therapy that we may be able to attenuate some of the untoward cardiovascular effects, all the while preserving the antagonistic features associated with the treatment for cancer.
Let's switch to the other sort of prospective original research format that we have in Circulation, and that's our letter format. Remember, our letters are addressing a specific point that can be readily appreciated in 800 words or less. The first is a letter by Anquetil et al that examines individuals recorded in the VigiBase World Health Organization database. This is basically a database organized around treatment of cancer and cancer therapeutics and it is examining those individuals that received sort of a newer class of agents called immune checkpoint inhibitors. Remember, that is modulation of our immune system to help attack cancer.
In some rare circumstances, relatively infrequent, when these agents have been administered, the immune system has been unlocked and attacks the heart, promoting a myocarditis that if not recognized can be fulminant and lead to death. This particular group identified a new phenomenon that we need to be aware of and that's just frank myositis.
Vlad, what are your thoughts on now perhaps these agents being associated with the development of myositis in the skeletal muscle?
Dr Vlad Zaha: Often when adverse events, as you mentioned Greg, are an important concern for these new powerful tools for the oncologists and it has been pretty early in the process where some of the cases have demonstrated severe cardiovascular events. Fortunately it is a very low percentage, less than 1% of cases that can manifest with fulminant myocarditis, but this raises again a question of expanding the view towards other systems when we are applying one of these early novel molecular interventions.
In this context, the recognition of myositis in another small percentage of patients is an important observation and increasing awareness of both cardiologists and oncologists towards this side effect is important as not all fatigue is equal and sometimes that can be due to manifestations of cardiomyopathy and sometimes it can be a manifestation of oxygen extraction in the peripheral tissue than muscle contractility. It is an important hypothesis-generating piece that will allow people to appreciate more of the complexity of addressing the intrinsic molecular mechanisms in cancer and heart disease.
Dr Greg Hundley: It sounds that we need to be aware of another potential etiology of fatigue to put in an armamentarium of differential diagnoses for those patients that are not getting quite back to where they were from an exercise and activity level after treatment. The second research letter focuses on individuals that are receiving a Fontan procedure. Remember, Fontan procedures are surgical corrections for those primarily with single ventricles where we're diverting caval blood to the pulmonary circulation, since in some situations there's really no functional right ventricle. These patients over time experience chronic venous hypertension and have associations with liver disease.
In this particular research letter, the authors are examining the relationship between really for the first report in an aggregate form of the relationship between undergoing a Fontan procedure and the development of hepatocellular carcinoma. Vlad, any quick comments to highlight on this particular procedure? I thought something that was interesting is that these individuals experienced these hepatocellular carcinomas in their 20s and 30s.
Dr Vlad Zaha: That's right, Greg. This study confirms observations from previous case reports and the early occurrence of hepatocellular carcinoma is raising still important hypotheses for future clinical trials. On one hand, either there is an increased risk of hepatocellular carcinoma development in patients with non-cirrhotic livers after a Fontan operation, or the current screening modalities using imaging are insufficiently sensitive to identify early signs of cirrhosis in such patients and this stratifies them effectively at an early stage in their disease post-op Fontan procedure.
Dr Greg Hundley: Lastly, let's just briefly discuss here, Vlad, some of the other editorials and review article formats that we have in Circulation. A particular one, a perspective that was written by Peter Libby and Ebert and associates that highlights this phenomenon potentially implicating inflammation and the link between cancer and atherosclerotic cardiovascular disease. The topic of this perspective is really on something called CHIP, which stands for clonal hematopoiesis of indeterminate potential.
What is this CHIP? As we age, basically what happens is we accumulate mutations of hematopoiesis stem cells in our bone marrow. Over time these little clones, they actually have within our bone marrow some survival advantages and they can spill out into the blood and actually can be associated with future leukemias. Those that have a large population of this particular clonal progeny, these CHIP-type cells, they have an increased risk of developing cancer, but also the levels of these are associated with increased overall mortality and it appears some risk of cardiovascular disease. How could that be? One characteristic of this particular cell line is they are associated with dysregulation of inflammatory genes that go on to produce, are associated with other inflammatory mediators.
Vlad, this is calling in question and helping us to examine the relationship between inflammation, cancer and cardiovascular disease. What are your thoughts here about these very important insights provided by Libby and Ebert?
Dr Vlad Zaha: This is a fascinating perspective, Greg. It really brings, again, in the offline novel molecular mechanisms that have been discovered recently and that are becoming a turning point into the molecular interventions, not only in cancer but potentially soon in cardiovascular disease prevention and treatment. Having a common root for a problem set involving such a prevalent cardiovascular problem as atherosclerosis and cancers reveals the connection between the different systems and the fact that integrating our understanding of the molecular regulation of cell proliferation results in an effective translation of leading to new targets and new approaches to treat disease.
It is striking that there are multiple areas where cancer and inflammation are interacting, one of them being at the cellular level and other ones at humoral levels, in a way reproducing other complex mechanisms that we see in regulation of inter-system interactions within the body.
Dr Greg Hundley: And so, summarizing this entire issue in Circulation, what a wonderful collection of a series of original manuscripts, both in the extended and the letter format as well as review articles, including a primer by Handy and associates that evaluates or draws attention to our screening tools that how we might examine the relationship between cardiology and the whole world or hematologic oncology related issues. And then this very unique perspective by Peter Libby and really is a continuation of the growth of this, as we called earlier, the bridging discipline of cardiovascular medicine and oncology as we work toward improving survivorship of all individuals with cardiovascular disease and cancer.
I want to thank you for the opportunity to be with you today and encourage you to follow these issues further with the journal. I'll turn this over to Vlad for any closing remarks.
Dr Vlad Zaha: Thank you, Greg. This has been a really exciting overview of important points that are emerging now at this nexus between cardiology and oncology that give us a broader view of the complex interactions that the future will materialize for us, emerging from a molecular intervention on cancer, heart disease, immunologic disease and probably metabolic endocrinology disease.
Thank you for listening.
Dr Carolyn Lam: Thank you so much, Vlad and Greg. This is a tremendous issue and I'm sure, audience, you will be reaching for it right now, I would.
Please let all your colleagues know 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.
Can proteomic biomarkers distinguish between subtypes of aortic stenosis even years before surgery? Well, to find out more, stay tuned. That's coming right up after these summaries.
The first original paper this week adds to the evidence that smoke-free policies are associated with a lower risk of cardiovascular disease. First and corresponding author, Dr Mayne from Northwestern University Feinberg School of Medicine, and her colleagues linked smoke-free policies to participants of the Coronary Artery Risk Development in Young Adults, or CARDIA study, which has a follow-up of up to 20 years. They found that smoke-free policies in workplaces were associated with significantly lower risk of incident cardiovascular disease after controlling for a wide range of covariants. Results were weaker for bar and restaurant bans, but in the same direction.
Preventive fractions range from an impressive 24 to 46%. Thus, smoke-free policies may improve cardiovascular health through reducing population exposure to tobacco smoke. However, we should remember that much of the US population remains unprotected by smoke-free policies. Thus, taken together with prior ecological work, these results support the continued expansion of smoke-free policies in indoor public places.
Most phase-3 randomized control trials feature time-to-first event end points for their primary analysis. In chronic diseases, however, a clinical event can occur more than once and recurrent event methods have been proposed to more fully capture the disease burden, as well as to improve statistical precision and power.
However, is this really the case? This question was examined by first author, Dr Brian Claggett, corresponding author, Dr Scott Solomon, from Brigham Women's Hospital in Boston, Massachusetts, and their colleagues, who sought to better characterize factors that influence the statistical properties of recurrent events and time-to-first event methods in the evaluation of randomized therapy.
They performed repeated simulated trials with 1:1 randomization of 4000 patients to active versus control therapy. Through simulation, they varied the degree of between-patient heterogeneity of risk as well as the extent of treatment discontinuation. They then compared their findings with those from the actual randomized control trials.
The authors found that the statistical power of both recurrent events and time-t- first event methods were reduced by increasing heterogeneity of patient risk, a parameter that's not usually included in conventional power and sample size formulae. Furthermore, data from real clinical trials were consistent with the simulation studies, confirming that the greatest statistical gains from the use of recurrent events methods occurred in the presence of high patient heterogeneity and low rates of study drug discontinuation.
The next paper uncovers a novel biomarker and therapeutic target of pulmonary arterial hypertension, and that is selenoprotein P. First author Dr Kikuchi, corresponding author, Dr Shimokawa, from Takaoka University Graduate School of Medicine in Japan and their colleagues performed micro-array analyses using pulmonary arterial hypertension, pulmonary artery smooth muscle cells, and found a 32-fold up regulation of selenoprotein P compared with controls.
Selenoprotein P promotes cell proliferation and apoptosis through increased oxidative stress and mitochondrial dysfunction. Using five strains of genetically modified mice, the authors demonstrated a pathogenic role of selenoprotein P in the development of hypoxia-induced pulmonary hypertension.
Furthermore, sanguinarine, which is an orally active small molecule identified by throughput screening reduced selenoprotein P expression and pulmonary arterial smooth muscle cell proliferation and ameliorated pulmonary hypertension.
In summary, this study shows that selenoprotein P plays a crucial role in the pathogenesis of pulmonary arterial hypertension and may be a useful and novel biomarker and therapeutic target in this disorder.
Familial hypercholesterolemia is known to be associated with a high risk of ischemic heart disease, including myocardial infraction, but what about the risk of ischemic stroke? Well, first author, Dr Beheshti, corresponding author, Dr Nordestgaard, from Copenhagen University Hospital and their colleagues examined the associations of familial hypercholesterolemia and high LDL cholesterol with ischemic stroke in both causal, genetic, and observational analyses using more than 106000 individuals from the Copenhagen General Population Study, and more than 10000 individuals from the Copenhagen City Heart Study.
They used a Mendelian randomization design to test whether high LDL per se had a causal effect on ischemic stroke risk using a combination of the familial hypercholesterolemia causative mutations and common genetic variants associated with high LDL.
The authors found that there was no association between familial hypercholesterolemia mutations and ischemic stroke risk. In the Mendelian randomization analysis, also including common genetic variants, there was also no causal effect of high LDL on the risk of ischemic stroke.
These findings imply that the predominant goal of targeting LDL lowering in those with and without familiar hypercholesterolemia is likely to reduce myocardial infractions, rather than ischemic stroke. Well, that wraps it up for our summaries. Now for our feature discussion.
Circulation publishes numerous papers regarding circulating biomarkers. We talk about biomarkers in the diagnostic, prognostic sense, but what about in a pathophysiologic sense, and especially in a disease as important as aortic stenosis? Well, that's what our featured paper this week is all about and I'm so excited to have with us corresponding author, Dr Stefan Söderberg, from Umeå University in Sweden, as well as our associate editor, Dr Peipei Ping from UCLA. We will be discussing the paper entitled “Proteomic Biomarkers for Incident Aortic Stenosis Requiring Valvular Replacement.” Stefan, could you tell us a bit about what made you look at this very interesting question, and perhaps the unique resources you had in Sweden to look at this?
Dr Stefan Söderberg: I'm a practicing cardiologist, and I have been working a lot with aortic stenosis over the years. It's frustrating that we can't do anything to stop the process. In many cases, the patients are old and frail, and if you could find the means to stop the process long before they need surgery, it will be of great benefit for the human and for the society.
Also, knowing that the interventions on the statins, for example, have been unsuccessful, we thought that there must be better ways or other biomarkers. Furthermore, that many of these studies, the phenotype of aortic stenosis has been very poorly described and there is probably much more behind just aortic stenosis than just, for example, calcium deposits in an X-ray, et cetera, et cetera.
Dr Carolyn Lam: You used some very unique resources in Sweden to therefore look at the proteomic signatures of aortic stenosis. Could you describe that and simplify perhaps the results so we can understand it?
Dr Stefan Söderberg: First of all, I got this idea from other studies done up in northern Sweden. If you have an absolutely unique setting, the combination of huge population-based studies in 30 years back, we have a huge biobank with examples of extraordinary good quality from each of these participants. For example, for each participant, the blood has been spun and put into freezer, deep freezer, within one hour for 30 years, and they are now, as I said, about 100000.
Furthermore, I'm working as a cardiologist at a university, and up here, you do all of the aortic surgery for the whole northern Sweden. That is, we can combine the names of the person undergoing surgery together with these population-based surveys and we can get details from all those who have participated in the surveys long before they did the surgery, and they can go and retrieve samples from cases and match controls from the freezers. It's a unique setup. Then, when we were designing the study, we got the chance to get these analyses done by our friends at the university to get the proteomic analysis via a unique data technique.
Dr Carolyn Lam: Wow. Could you describe your results?
Dr Stefan Söderberg: The results that we found in the first set of 334 patients who underwent surgery is 10 years after their first sampling, we found six proteins. Then, we got the question back from Circulation to establish a validation cohort, and we were able to do so to include all those new cases in the last 2 years, and there we could replicate five of these proteins.
The interesting thing that the pattern is completely different between those having coronary artery disease from those without. That kind of phenotyping has not been done throughout other aortic stenosis studies. Therefore, this study is unique. We have had two papers in the last year in the Journal of American Heart Association from the cohort, as well, showing the thing that happened.
For example, lipoprotein little A is only associated with future aortic stenosis valve replacement only in those with concomitant coronary artery disease. There are many unique things, the prospective design, and the phenotype differentiating those with and without coronary artery disease.
Dr Carolyn Lam: Yeah, and if I may just reiterate that the population base that you work with is just enviable and just so that the audience realizes, these are biomarkers that were collected 11 years before the aortic stenosis surgery, isn't it? You really had a long follow-up.
Also, just to let everyone know, it was a proximity extension assay that you used for the discovery, and the six proteins were growth differentiating factor 15, or GDF15, galectin-4, von Willebrand factor, interleukin 17 receptor A, transferrin receptor protein 1, and PCSK9, so very interesting. Peipei, you have a way of putting things into context so beautifully. Could you tell us your thoughts when you saw this paper?
Dr Peipei Ping: I thought this is a very high-quality study that actually benefited from the long-term established, well-controlled cohort in northern Sweden, as Dr Söderberg just shared with us. On the other end, it married a technology platform that's very well-established and -validated, and this situation targeted proteomics platforms using multi-proximity extension assays with carefully controlled markers and screened 92 cardiovascular candidate markers.
This is the kind of approach that provides semi-quantitative as well as quantitative outputs and is capable to offer validated screens on large population clinical subsets. A study of such with a high value cohort combined with a validated and well-controlled technology platform offered results that clearly have clinical significance, as well as setting up examples for other studies to follow. The enthusiasm from the editorial boards, as well as the reviewers, have been substantially high and supportive.
Dr Stefan Söderberg: Fantastic. I'm very glad to hear this.
Dr Carolyn Lam: Stefan, you also mentioned that a very unique element was the separation of aortic stenosis with and within coronary artery disease, or at least established or visible coronary artery disease. Could you explain how that provided pathophysiologic insights?
Dr Stefan Söderberg: First, I should say we were very, very strict. Our routine is that everyone was 100% undergoing, aortic valve replacement, they undergo a coronary angiogram before. If we saw any sign of atheromatosis, it was not enough that they had the significant stenosis, but any signs, they were put into the group of coronary artery disease. Those without, we couldn't see anything there. Radiograph here reported absolutely clean coronary arteries. Of course, we cannot exclude if there were aortic changes within them all, of course.
We believe that this is a very important message that in order to further study aortic stenosis, we should be very careful in phenotyping the disease. We hope the growing cohort will be able to do this further. For example, cuspid versus tricuspid valves, women versus men, et cetera.
My answer in short is phenotype. Let me take one example which I found very, very exciting. That is the finding of PCSK9, which is closely related not only to cholesterol symptoms, but also to lipoprotein little A emphasis. As you know, the first strong finding in aortic stenosis was the LP little A. This is related to that genetic finding, and that was in the huge study from Canada. They did not have the same phenotyping, so we had information to his important findings. That's one example.
Another example is the transferring receptor, where data has shown that bleeding acutely in the valvular tissue causes damage, and this relates iron metabolism to the formation of the aortic valve. Obviously, it seems that the process in the aortic valve is very much similar to the vessel arteriosclerosis. It seems to be different. This is the indication that when we formulate new studies or new drugs on aortic stenosis, we must be very careful to use the right drug for the right type of valvular disease.
Dr Carolyn Lam: Those are great points. Peipei, do you think that's the main clinical take-home message, beyond that great comment you made earlier that this paper's just a great example of the use of tools, modern tools, that we have in proteomic characterization like the proximity extension assay to provide pathophysiologic insights when you have a really well-phenotyped cohort? What's the critical take-home message, though? Is there one now?
Dr Peipei Ping: The take-home message is marriage of amazing high value cohort's data sets with that of the well-controlled clinical study using target proteomics approaches. In this particular study, one main critical innovation is the study is capable of providing insights regarding molecular signatures that have predicted values. As stated in the manuscript, the circulating proteins that found critically important, their alterations took place years before the surgery were associated with aortic stenosis. That is of value, clinical value, to many other clinical studies to follow.
Dr Carolyn Lam: Wow. That's wonderful. Thank you so much for putting these findings in context for us. Thank you, listeners, for joining us today. Don't forget to tune in again next week.