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 Centre and Duke National University of Singapore.
Have you ever wondered, which is better for heart health, low calorie vegetarian or a Mediterranean diet? Well, this week's feature paper provides some answers with a very intriguing discussion coming right up after these summaries.
The first original paper this week suggests that human fat pools are not the same and in fact are highly diverse in their response to lifestyle interventions during weight reduction first author Dr. Gepner, co-corresponding authors Dr. Shai from Israel and Dr. Stampfer from Boston aim to assess whether distinct lifestyle strategies could differentially affect specific body adipose depos. They performed at 18-month randomized control trial among 278 sedentary adults with abdominal obesity or dyslipidemia in an isolated work place with a monitored, provided lunch.
Participants were randomized to an isocaloric low fat or a Mediterranean low carbohydrate diet with or without added moderate physical activity. The overall primary outcome was body fat redistribution and the main specific endpoint was visceral adipose tissue. The authors further followed the dynamics of different fat depos by magnetic resonance imaging. They found that Mediterranean diet was superior to the low fat diet in mobilizing specific ectopic fat depos such as visceral, hepatic, cardiac and pancreatic fats. Exercise had an additional independent contribution to visceral fat loss. Long term persistent moderate weight loss inadequately reflected the significant beneficial effects of diet and exercise on the fat depos. Independent of weight loss, visceral and hepatic fat reduction was mainly associated with improved lipids profile whereas deep subcutaneous fat loss was associated with improved insulin resistance and superficial fat loss was neutral.
In other words, two distinct patterns were identified, a differentially responsive depo that was sensitive to the type of intervention, and those recites mostly directly related cardiometabolic health and a uniformly responsive depo, which corresponded only to weight loss per se irrespective of the intervention. Overall, these results suggest that more specific strategies for weight loss may be considered to treat distinct organ specific fat depos in the management of cardiometabolic risk.
Current guidelines recommend nonvitamin K antagonist oral anticoagulants or NOACs in patients with nonvalvular atrial fibrillation as these drugs have several benefits over the vitamin K antagonists but do these benefits remain when NOACs have to be combined with aspirin therapy? Well co-first authors Dr. Bennaghmouch and de Veer, corresponding author Dr. ten Berg and colleagues from the Netherlands provided a meta analysis comparing NOACs and Vitamin K antagonists in more than 21700 patients with atrial fibrillation who are treated with concomitant aspirin therapy. NOACs were found to be more effective in terms of stroke or systemic embolism reduction as well as vascular death reduction and as safe as vitamin K antagonist with respect to major bleeding. NOACs were in fact safer with respect to the reduction of intracranial hemorrhage. Thus, these authors found that NOACs were an effective and safe alternative as compared to vitamin K antagonists in atrial fibrillation patients treated with concomitant aspirin therapy.
The next study shows that an integrative approach using genomics and proteomics has the potential to identifying new biological pathways for biomarker discovery and pharmacologic targeting in early cardiovascular disease. Co-first authors Dr. Benson and Yang, co-corresponding authors Dr. Wang and Gerszten from Beth Israel Deaconess Medical Center in Boston had recently identified 156 proteins in the human plasma that were each associated with a net Framingham cardiovascular disease risk score using an aptamer-based proteomic platform in the Framingham Heart Study Offspring participants.
Now, in the current student these authors hypothesized that performing a genome-wide association study and exome array analyses on the levels of each these 156 proteins may identify genetic determinants of risk associated circulating factors and provide insights into early cardiovascular pathophysiology. Indeed, they discovered dozens of novel genetic variants that were each strongly associated with circulating levels of the Framingham Risk Score associated proteins. They highlighted numerous examples of how these novel gene locus protein associations provided new insights into cardiovascular disease risk pathophysiology including a novel pathway by which the gene phosphatase 1G modulated circulating levels of apolipoprotein E, a key regulator of cholesterol handling.
The final study suggests that bariatric surgery represents an effective strategy for reducing antihypertensive drugs in patients with obesity and hypertension. First and corresponding author Dr. Schiavon from Heart Hospital in Sao Paulo, studied 100 patients with obesity and hypertension who were randomized to gastric bypass or medical therapy alone. The patients randomized the gastric bypass were six times more likely to reduce by 30% or more the total number of antihypertensive medications while maintaining controlled blood pressure levels. In addition, 51% of the patients undergoing gastric bypass showed remission of hypertension. Now, the authors are quick to alert that given the morbidity of surgery these results do not imply that all patients with obesity and hypertension should be submitted for bariatric surgery. Rather, these results suggest that gastric bypass surgery represents one extra option to consider in achieving blood pressure control in these patients.
That wraps it up for our summaries now for our feature discussion.
So, which is better for heart health the vegetarian or the Mediterranean diet? Oh, what an awesome topic and to be able to discuss it from Asia to the United States to Italy, I'm so please to have the first and corresponding author of our feature paper this week Dr. Francesco Sofi from University of Florence in Italy and our dear associate editor Dr. Wendy Post from Johns Hopkins. Francesco, could you please start by telling us what inspired you to do this trial?
Dr Francesco Sofi: The aim of the study was to compare two of the most beneficial diets we know from the literature in relation to the occurrence of many chronic degenerative diseases so the Mediterranean diet we have a lot of studies showing that Mediterranean diet is beneficial for many different diseases as well as we have some studies for the beneficial effect of a lacto-ovo vegetarian diet but no studies are available comparing these two diets' dietary profiles. Our hypothesis was to compare in the same population different times the two diets, which were the similar calories, the same isocaloric but just different in terms of composition especially for meat and fish.
Dr Carolyn Lam: Tell us the bottom line. I'm holding my breath because I think I've said it before, I'm vegetarian. Half my household is Mediterranean diet so what did you find?
Dr Francesco Sofi: We found that in the same group of patients, which were a low risk population because a low risk population here in Italy they were already following a Mediterranean diet but if you control their calories and their composition in terms of the Mediterranean, which included all the different food groups and the lacto-ovo vegetarian diet so all the different groups except for meat and meat-based and fish we noticed that after three months, the lacto-ovo vegetarian diet already determined a reduction of total cholesterol and LDL cholesterol and Mediterranean diet already determined reduction of triglycerides and both were effective for reduction of body weight and fat mass.
We noticed with great interest that after three months, all the study population were quite good in [inaudible 00:09:45] with this diet. I mean they didn't have any kind of problems. This is the one of the most important thing and most of the population or many of the patients after the end of the study they started or continued to follow a vegetarian diet. It means that they accepted very well. There was no problem at all. Also, in feasibility and acceptability of this diet and in relation to this also they have a beneficial effect in some parameters such as also oxidative stress parameters and the inflammatory parameters.
Dr Carolyn Lam: Right, so if I could summarize maybe crudely so the vegetarian diet, very effective for LDL, the Mediterranean very effective for triglycerides. I know that's a simplification but Wendy, I'd like to know do you think this is the dawn of maybe a more, "Oh, here we go again individualized diet planning"?
Dr Wendy Post: I think that this study is really important because there really have been few randomized trials about the vegetarian diet and we've learned a lot of the potential beneficial effects of a Mediterranean diet. I think what was really interesting about this study is seeing that they were both equally effective as a low calorie Mediterranean diet or vegetarian diet at reducing body weight, which is most often the biggest challenge for our patients who are either at risk for cardiovascular disease like these patients potentially were or who have cardiovascular disease.
I think the vegetarian diet is potentially an excellent option for some of our patients but it really is an individual choice and I have trouble getting some patients to just give up the red meat let alone any kind of animal meat. I think it really is potentially an individual choice and those who are interested in becoming vegetarian for either health reasons or other reasons these are additional data to suggest potential beneficial effects more to the Mediterranean diet.
Dr Francesco Sofi: I think one of the most important things to know from this study is that we have now two options. We need to individualize the diets to patients but if a person wants to follow a vegetarian diet for different reasons including also healthy reasons, we can say that it's beneficial. He or she can follow this diet without no problems so without having any health problems as well as if a person wants to follow also a Mediterranean diet, which included meat and fish with a regular and moderate consumption during the week.
Dr Wendy Post: Right but this is just a three month trial with intermediate outcomes so I'm not sure we can necessarily make definitive statements that this is potentially not leading to any adverse effects or some of the other statements that you made. I think we could just make the statements better relative to the outcomes that were seen here related to weight loss and traditional cardiovascular risk factors. Whereas, we have had long term clinical trials of the Mediterranean diet suggesting reduction in risk for events so I think this is definitely supportive of the vegetarian diet but I think we can't say that more studies aren't needed to potentially look at longer term outcomes and more definitive events as opposed to intermediate outcomes that this is a great first start and is really helpful in trying to understand some of the potential differences between the vegetarian diet and the Mediterranean diet.
Dr Francesco Sofi: Of course, I completely agree on that. We need more studies and larger studies and longer duration to establish some things but it was just a pilot study but the good thing is the first comparing two beneficial diets. In the literatures now, most of the studies were investigated either already a vegetarian person or vegetarian diet versus a westernized diet so probably there were some biases.
Dr Carolyn Lam: Indeed, I want to just echo in these words. Congratulations, Francesco. Beautifully done, very elegant, controlled in terms of caloric intact and I like that message that it's not saying that one is bad and the other is good. It's saying, "They're different but they both resulted in weight loss". I love that comment about getting a bigger study. I want to do it right here in Asia because the diets are just so different here and I'm just wondering how about in the US? Wendy, your perspective? How adoptable are these results?
Dr Wendy Post: Well, again I think it's a personal choice and if somebody is willing to become vegetarian then that's potentially wonderful especially if they have high LDL cholesterol and are trying to lose weight but we have to be careful about with the vegetarian diet is the carbohydrate intake, which might affect triglycerides. It might be an individualized approach based on the patient's individual risk factor profile and they're preferences but this is really impressive data suggesting that the vegetarian diet is very similar to the Mediterranean diet in many aspects especially as it relates to weight loss, which is really important.
Dr Carolyn Lam: You've hit the nail on the head. Let's remember that this is a low calorie vegetarian diet. I think that's the issue. Sometimes when I say vegetarian diet to some communities here in Asia that is actually a lot of calories and a lot of starch, which is not what we're talking about here.
Dr Wendy Post: Right, a low calorie diet so that's the key. That's the hard part isn't it?
Dr Carolyn Lam: Yeah, sadly.
Dr Francesco Sofi: We should say that most diets are similar background I mean in the backbone is similar so a dietary profile full of fruit and vegetables, complex carbohydrates, fiber, so the different things are meat and fish but with you can see in a regular consumption also Mediterranean diet of course, especially Mediterranean diet is beneficial for cardiovascular profile.
Dr. Wendy Post: Yeah, if we could get our patients in the United States to follow either the vegetarian or the Mediterranean diet that would be fabulous because they are obviously eating too much in the way of sugar sweetened beverages and deserts and fast food so just trying to follow either of these diets would be especially beneficial if it was a low fat vegetarian or Mediterranean diet. I think we need to get all our patients to be eating more fruits and vegetables, which is a key component of both of these diets and what they share in common, which often can lead to beneficial effects with weight loss due to the increased fiber and satiety and the healthful benefits of high fruit and vegetable diet.
Dr Carolyn Lam: Thank you so much.
Audience, thanks also for joining us. You've been listening to Circulation on the Run. 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 Doctor Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. This week's journal features an international external validation study of the 2014 ESE Guidelines on Sudden Cardiac Death Prevention in Hypertrophic Cardiomyopathy. A very exciting discussion coming right up after these summaries.
The first original paper this week suggests that proteomics, a tool of precision medicine may prove useful in improving the safety and efficiency of drug development. First author, Doctor Williams, Corresponding Author, Doctor Ganz, from the Zuckerberg San Francisco General Hospital retrospectively applied large scale proteomics to blood samples from Illuminate, the trial of Torcetrapib, a cholesterol estrotransfer protein inhibitor, which raised HDL and lowered LDL cholesterol. Recall that this trial was terminated due to increases in cardiovascular events and mortality.
In the current study, the authors found that plasma concentrations of 200 proteins changed significantly with Torcetrapib. Their pathway analysis revealed unexpected and widespread changes in immune and inflammatory functions, as well as changes in aldosterone function and glycemic control. A previously validated nine protein risk score was similar in the two treatment arms at baseline, but higher in participants with subsequent events. At three months, the absolute nine protein derived risk increased in the Torcetrapib plus Atorvastatin arm compared to the Atorvastatin only arm. Thus, this protein-based risk score predicted harm from Torcetrapib within just three months. A protein-based risk assessment embedded within a large proteomic survey may prove to be useful in the evaluation of therapies to prevent harm to patients. This is discussed in an accompanying editorial entitled "Harnessing the Power of Proteomics to Assess Drug Safety and Guide Clinical Trials" by Doctor Maggie Lam and Ying Ge.
The next study suggests that personalized monitoring of heart transplant outcomes may be achieved by profiling the genetic and phenotypic markers of the CD16-dependent natural killer cell activation pathway. First and corresponding author Dr. Paul from Vascular Research center in Marseilles in France and his colleagues collected blood samples from 103 patients undergoing routine coronary angiography for cardiac allograph vasculopathy diagnosis, a median of five years since their heart transplantation. They used a non-invasive natural killer cellular-humoral activation test to evaluate the association between genetic and phenotypic markers of the CD16 dependent natural killer cell activation pathway. They showed that the Fc-gamma receptor IIIAVV polymorphic variant, which encodes the highly responsive CD16-Fc receptor, was an independent baseline predictor of cardiac allograph vasculopathy, and may be useful for stratifying patients at higher risk of rejection. The implications of these findings also include the fact that individualized natural killer cell targeted therapies may limit vascular damage in responsive patients.
The next study suggests that estimation of polygenic atrial fibrillation risk is feasible, and together with clinical risk factor burden, can explain lifetime risk of atrial fibrillation. Co-first authors Dr. Weng and Preis, corresponding author Dr. Lubitz from Massachusetts General Hospital, and colleagues estimated the lifetime risk of atrial fibrillation in individuals from the community-based Framingham Heart Study. Polygenic risk for atrial fibrillation was derived using a score of approximately 1000 atrial fibrillation-associated SNPs. Clinical risk factor burden was calculated for each individual using a validated risk score for incident atrial fibrillation comprised of height, weight, systolic and diastolic blood pressure, current smoking, anti-hypertensive medication use, diabetes, history of myocardial infarction, and history of heart failure.
They found that the lifetime risk of atrial fibrillation after age 55 years was 37 percent was substantially influenced by both polygenic and clinical risk factor burden. Among individuals free of atrial fibrillation at the age of 55 years, those in the low polygenic and clinical risk tertiles, had a lifetime risk of 22 percent, whereas those in the high risk tertiles had a risk of 48 percent. Atrial fibrillation developed at an older age among individuals with a favorable clinical risk profile regardless of genetic predisposition. Nevertheless, the lifetime risk of atrial fibrillation in individuals with high genetic predisposition was substantial, even when the clinical risk factor burden was low. Thus, individualized projections of lifetime risk of atrial fibrillation may be refined by accounting for both genetic predisposition and clinical risk factor burden.
The final study tells us that in contrast to previous perceptions, Takotsubo cardiomyopathy has long-lasting clinical consequences. First and corresponding author Dr. Skally from University of Aberdeen in the UK and their colleagues did an observational case controlled study of 37 patients with prior Takotsubo cardiomyopathy and 37 age, sex, and co-morbidity matched controls. Although Takotsubo cardiomyopathy occurred 20 months before the study, the majority of patients had persisting symptoms compatible with heart failure and cardiac limitation on exercise testing. Despite a normal left ventricular ejection fraction in serum biomarkers, patients with prior Takotsubo cardiomyopathy had impaired cardiac deformation indices on echo cardiography, increased native T1 mapping values on cardio magnetic residence imaging and impaired cardiac energetic status on p31 spectroscopy. Taken together, these findings demonstrate that after Takotsubo cardiomyopathy, patients appear to develop a persistent long-term heart failure phenotype.
Well that wraps it up for our summaries. Now for our featured discussion.
Sudden cardiac death prevention and hypertrophic cardiomyopathy. Always such an important topic. I'm so pleased to have with us the author from our featured paper this week, Dr. Perry Elliot from University College London, nd our associate editor, Dr. Mark Link from UT Southwestern who also wrote a beautiful accompanying editorial with Tera Lynn Ho. So welcome both of you. Perry, I think to set us up, I'd really love if you could tell us a little bit more about the 2014 ESE guidelines for sudden cardiac death prevention and hypertrophic cardiomyopathy. And particularly pointing out how they may differ from the 2011 ACC AHA guidelines please.
Dr Perry Elliot: So, the 2014 guideline on sudden death prevention HCM, the aim of that guideline was to try to quantify the risk of sudden cardiac death. As you pointed out, sudden death is a significant complication of hypertrophic cardiomyopathy and one which we all as clinicians spend a lot of time trying to determine. If we look back over at, I don't know, a period of twenty, thirty years the approach we've developed is based upon the recognition of a number of clinical features of the disease that we know associate with a higher risk of sudden death. So things such as, you know, unexplained syncope or severity of hypertrophy. And it was that model of sort of taking those so called major risk factors which form the basis of the 2011 US guidelines and the essential model was the more of those things you have, the greater is your risk, and I suppose the higher indication for an ICD.
One of the problems with that approach was that it's not quantitative so you know, you could say, "Okay. Well I think you're at higher risk, but I can't say how much that risk is." And another problem with that way of doing things is when you start to think about some of the individual risk factors, it doesn't make a great deal of sense clinically.
And I suppose a good example of that is wall thickness. You know we have this magical number of 30 millimeters, above which we say you're at risk, but of course are we really saying that if your wall thickness is 29 millimeters you're at low risk? We know it doesn't really work that way in biology. So when we drew up the 2014 guideline we wanted to say, "Okay let's develop a model in exactly the same way that we do with atrial fibrillation or primary prevention in coronary disease so that we can say to the patient sitting in front of us, 'Based on your clinical assessment we think you've got a one, five, ten percent risk of something bad happening to you in the next five years.'" And then we can use that information to inform our decision about ICD implantation.
The model itself is not so revolutionary. I mean, it uses a lot of the conventional risk factors such as wall thickness, such as non-sustained VT on Holter monitoring, but what it did introduce was the factor of age, because we know that the age of the patient certainly determines their risk. We brought in [inaudible 00:10:12] obstruction because we've now got reasonable evidence showing that if you've got a big gradient, that certainly modulates your risk. And also probably for the first time, I suppose, left atrial size, which was one of those missing things I think in previous assessments. You know, it's a fantastic surrogate for restrictive physiology and certainly when we added it to the model it improved the predictive power of that model.
So I suppose in summary what we've done is to produce a tool which allows you to estimate risk and then use that to help you decide on whether an individual needs a defibrillator in the clinic.
Dr Carolyn Lam: You know Perry I believe you led those guidelines and I just want to congratulate you as well as that was such a beautiful explanation of what was going on behind those. Yup, but the proof is in the pudding isn't it? But you're providing that proof in today's paper. Tell us about it. So it's an external validation, a large international multi-centers study to actually validate these 2014 guidelines.
Dr Perry Elliot: That's right. I mean, I think when we generate these kind of models it's really important to test those models in different settings. The original model was based upon a relatively small number of European centers and I think what this paper does is it brings insights into different geographies and different health care systems. So we have participating centers from North America from the Middle East from the Far East and the idea here is to get as diverse a population as we can and just see if the model performs in the same way. And you know in a study just short of 4000 people, I think that we've shown that the model does indeed seem to behave in the same way. In fact, the numbers were remarkably similar. You know the ability of this model to discriminate between high and low risk patients was almost exactly the same as in the original paper, which I think gives us a level of reassurance that this model, this tool that we've developed, can be used in different health care settings.
Dr Carolyn Lam: Mark. I really enjoyed your editorial. I love the way that you started out with a case that really shows why this is so important. And I also love that you discuss some other studies that tried to validate the 2014 ESE guidelines as well. Could you just give us some of your thoughts there.
Dr Mark Link: Yeah. I first want to congratulate Perry and his fellow authors for this paper. I think it was a very nice paper. I was a champion of this paper from the time it got sent into circulation. And, you know, the big change in the 2014 European guidelines compared to the American guidelines is really the linear risk of age, wall thickness, and I'll put tract gradient. And as Perry says, I agree, it's not a simple you have it or you don't, it's a linear risk and I applaud them for including that in their risk factor stratifier. And if you look at the current paper, I mean it was very good at picking out high risk patients. So if you have greater than a four percent, six percent risk over five years, you did. And so for picking out the high risk patients it was very good. And for picking out the medium risk patients, it didn't function as well. It was best for separating out the high risk and the low risk population.
And I will say, based on this paper, I've started using the European risk stratifier in my clinical practice. So I do want to applaud them, you know, for the risk stratifier tool and this paper. But I do want to say, and I'm sure Perry will agree, that we're not there yet. We need better tools, because not only in this data set but in other data sets, because more of these individuals reside in the low risk population, more of the sudden deaths are in that population. And we need better tools. And over time they will come. You know, they may be MRI tools. They may be scar tools. They may be other tools that we aren't even aware of that are coming on the horizon, but we do need better tools as we move forward to identify those at risk for sudden death in hypertrophic cardiomyopathy.
Dr Perry Elliot: Yeah. No. I agree. I mean I think what I would say is if you sort of take a step back and look at the overall perspective in this paper, despite the fact that, you know, we've got nearly 4000 people and they're followed in different health care settings, the overall sudden death rate in hypertrophic cardiomyopathy pretty low. You know, so that's good for patients 'cause I think it shows that at least in managed populations, the risk of sudden death which is real and we've got to assess it, but I think it's really important to get that message over to patients that for most people with HCM they're at low risk. It is of course the challenge because when you're dealing with rare events, it's really hard to predict them. And this model is far from perfect. I would argue it's probably the best we've got for the moment, but you know, it's not that bad. It's not that bad.
I mean agree with you absolutely Mark, 'cause you know, either end it performs pretty well. In the middle there it's not as predictive, although what it tends to do is overpredict, rather than underpredict. So you know, I think if you use this model in your every day practice just the greatest risk is that you'd end up putting in probably more ICDs then you really need to rather than missing a lot of patients. You know, we really want to prevent every sudden death if we possibly can, but that's always going to be really hard I think and I think the fight goes on. We got to look for new risk predictors. It may be that we can interchange some of these predictors. They might be easier to assess in some practices, but I'm not a born optimist, but I really think it's amazing just how well in such a complex heterogeneous disease that this relatively simple assessment works. You know?
Dr Mark Link: Going forward, what do you think the future of HCM [inaudible 00:15:47] stratification will include? We've got the risk stratifiers in your calculator ready. And more specifically where do you think gadolinium enhancement will play a role in the future? So MRI findings of scar or gadolinium enhancement.
Dr Perry Elliot: The base we have at the moment show that the more scar you have, the greater risk of sudden death. It sort of makes sense, doesn't it? It's part of that substrate for ventricular arrhythmia. My own reading of it just so far is that I'm not sure what it adds to the existing way of doing things. I mean I think this is true of any biomarker, you know. I've got a new biomarker, what does it tell me that I don't already know? And with scar, we know the greater amount of scar, it often tracks with wall thickness. You're likely to have a thicker heart, you're more likely to have non-sustained VT. But I'm openminded on that front. The beauty about this model, for me, is that it's a tool to into which you can plug other things and you know, if we can get big enough data sets and we can use gads and the amount of scar and put that into the model and if it improves the performance of the model that's great. Those studies are underway at the moment and I think we eagerly wait the results of those studies.
For me, one of the missing things is the genetics. This is a heterogeneous disease with quite a complex genetic architecture, and despite the fact that you know it's 20, 30 years now since we identified the first gene, we haven't really factored that in to our risk models and I think that for me is one of the big challenges and opportunities over the coming years is to put together really large international data sets so that we can answer once and for all whether your mutation determines your prognosis.
Dr Mark Link: Yeah. I agree with the genetics also I think getting more information on that. And it’s been 30 years it still is not helping us prognosticate the risk of sudden death, but it should. I mean it really should. And I do think hopefully we will find other tools also as time goes on because it really is imprecise and it's very difficult when you're sitting there in front of ... You know, I just had a 20 year old yesterday come in with his family and he's got a three centimeter septum and he's got 12 percent scar and he's saying, "Gee what would you do and what would you do if I were your son?" And it's easy when you're looking at it in the aggregate. It's much more difficult when you're sitting there one on one with a patient in front of you.
Dr Perry Elliot: Of course. Of course. And I think another factor I think which is changing the dynamic of that kind of discussion is the evolution of ICD technology. You know, I think when you're dealing with young people the fear is long-term complications with leads isn't it? And I think with the advent of the SICD I sense it's already tipping the balance into perhaps a slightly more liberal approach to ICD implantation exactly in the kind of scenario you've just described Mark, you know you've got guy who's 20. He's got a really severe hypertrophy. Well you know, if you and mess ICD you know your threshold for implantation might be a bit lower.
Dr Mark Link: Yeah and in fact, after a two hour discussion that's what we decided on is that subcu ICD was the right thing for him. And everyone's very happy with that choice.
Dr Perry Elliot: Yep. I think it also raises another thing which I often think about is that as medics we're also probably not good at considering what acceptable risk actually is. You know? We develop models in different settings and hyeprtrophic cardiomyopathy, coronary disease, heart failure, and actually if you go back and critically look at the thresholds that are used to put in defibrillators, the absolute risks vary enormously. So you know, here in [inaudible 00:19:02] we're talking about an approximate annual risk of sudden death of about one percent per annum is sufficient to put in an ICD, but in long-QT world it's quite a different threshold that's used and of course that's because there is no defined number. You know the number's we used in the ESE model of greater than six percent you should have an ICD, well yeah that's the consensus number, there's nothing magical about it. There's nothing biological about it. And I think we've probably had greater debates at what acceptable risks really are.
Dr Mark Link: And that's become a big shared decision now in the States and actually everywhere. It's become a big word because it sued to be that the physicians would decide on who gets an ICD and who doesn't. And it's no longer that way it's a discussion with the patient, with the family. How much risk are they willing to take, both with an ICD and without an ICD, because there are issues with ICD, even though I'm a big fan. There are issues and especially with transvenous ICDs, but also with subcutaneous ICDs.
Dr Perry Elliot: Absolutely. Absolutely.
Dr Mark Link: You know, it's a different world now than it was 15 20 years ago.
Dr Carolyn Lam: Perry and Mark, this has been one of the most wonderful conversations I've had on these podcasts. I just can't thank you enough. I'm sure all our listeners are thanking you too. You've been listening to Circulation on the Run. You must tune in again next week for more beautiful conversations.
Dr. Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal it's editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center, and Duke National University of Singapore. The new ACC/AHA hypertension guidelines are hotly discussed. So much so that we have invited perspectives of these new guidelines from around the world and authors will be discussing this right here on Circulation on the Run. Stay tuned, as it's coming right up after these summaries.
The first original paper this week is a translation study suggesting that the parasympathetic system may be a novel therapeutic target in pulmonary arterial hypertension. Co-corresponding authors Dr. Handoko and de Man from University Medical Center Amsterdam used heart rate recovery after maximal cardiopulmonary exercise testing as a surrogate for parasympathetic activity, and assessed white ventricular ejection fraction in 112 patients with pulmonary arterial hypertension. They found that patients with a lower right ventricular ejection fraction had a significantly reduced heart rate recovery compared to patients with a higher right ventricular ejection fraction.
Furthermore, they looked at tissues from the right ventricle of 11 patients undergoing heart-lung transplantation, and found that there was increased expression of nicotinic receptors with no difference in muscarinic receptor expression compared to controls.
Finally, in a rat model of pulmonary hypertension, they showed that chronic pharmacologic sympathetic stimulation by pyridostigmine, which is an acetylcholinesterase inhibitor, improved surviving right ventricular function and reduced pulmonary vascular remodeling.
In summary, the study shows that right ventricular dysfunction is associated with reduced systemic parasympathetic activity in patients with pulmonary arterial hypertension, with an inadequate adaptive response of the cholinergic system in the right ventricle. Furthermore, enhancing the parasympathetic activity in these patients may be a novel therapeutic strategy.
Dr. Carolyn Lam: The next study unveils a new mechanism by which pericardial adipose tissue coordinates immune cell activation and outcomes following a myocardial infarction. First author Dr. Horckmans, corresponding author Dr. Steffens, and colleagues from Institute of Cardiovascular Prevention in Munich identified larger B-cell clusters in epicardial adipose tissue of human patients with coronary artery disease compared to controls without coronary artery disease. Furthermore, they showed that infarcted mice had larger pericardial clusters, and a 3-fold up regulator numbers of GM-CSF producing B-cells within the pericardial adipose tissue, but not in the spleen or lymph nodes. This was associated with higher dendritic cell and T-cell counts in the pericardial adipose tissue.
Further experiments show that activated dendritic cells migrated from infarcts into the pericardial adipose tissue. Cytokines and growth factors released locally within the pericardial adipose tissue as well as systemically promoted immune cell proliferation and emergency granulopoiesis after myocardial infarction.
Finally, the enhanced fibrosis and worsened ejection fraction in mice was limited by removal of the pericardial adipose tissue.
In summary, these pre-clinical data suggest that pericardial adipose tissue may be a central compartment for innate and adaptive immune responses, which regulate post-myocardial infarction healing.
Dr. Carolyn Lam: The next study reports for the first time in a large, comprehensive national cohort study, the incidence of atrial fibrillation in children and young adults with congenital heart disease. First and corresponding author Dr. Mandalenakis and colleagues from University of Gothenburg in Sweden used data from the Swedish Patient and Cause of Death registers to identify all patients with a diagnosis of congenital heart disease who were born between 1970 and 1993. Each patient with congenital heart disease was matched by birth year, sex, and county with ten controls from Sweden. Follow-up data were collected until 2011.
The authors found that the risk of atrial fibrillation in children and young adults with congenital heart disease was 22 times higher than that in matched controls. Up to the age of 42 years, one in 12 patients with congenital heart disease had developed atrial fibrillation and one in 10 patients with congenital heart disease with atrial fibrillation had developed heart failure. In particular, patients with the most complex congenital malformations, conotruncal defects, had the highest risk to develop atrial fibrillation. These patients should be considered for targeted monitoring.
Dr. Carolyn Lam: The next study provides a novel and simple risk score for right-sided heart failure in adults undergoing Left Ventricular Assist Device implantation with the current mainstream devices. First and corresponding author Dr. Solomon and colleagues from University Medical Center Rotterdam studied almost 3000 adults who underwent continuous flow Left Ventricular Assist Device implantation in the largest EU registry of mechanical circulatory support devices. They derived and validated a right-sided heart failure prediction model that out-performed several published scores and well-known hemodynamic and echocardiographic individual markers of right-sided heart failure.
This prediction model included the following risk factors: need for three or more inotropic agents, inter-agency registry from mechanically-assisted circulatory support class one through three, severe right ventricular dysfunction on semi-quantitative echo cardiography, ratio of right atrial to pulmonary capillary wedge pressure of more than 0.54, and a hemoglobin level of less than 10 grams per deciliter.
These findings offer a step towards improving prediction of the risk of right-sided heart failure to target future optimal strategies aiming at early and intension right-sided heart failure management for the highest risk subgroups of patients undergoing Left Ventricular Assist Device implantation.
Dr. Carolyn Lam: Now, sharing a patient-level clinical trial data has been widely endorsed, but just how extensively have these data been used for cardio metabolic diseases? The final study this week attempts to answer this question. First and corresponding author Dr. Vaduganathan and colleagues from Brigima Women's Hospital extracted data from clinicalstudydatarequest.com, a large, multi-sponsored data sharing platform hosting individual patient-level data from completed studies sponsored by 13 pharmaceutical companies.
They found that the median time from study completion to data availability was more than six years. Most data requesters of cardio metabolic clinical trial data were from academic centers in North America and Western Europe, and half the proposals were unfunded. Only 15% of these trials had been accessed by investigators thus far, and few findings have reached publication. Most requests for shared data access focused on new hypothesis generating questions rather than validation of the original study findings. These data may allow anticipation of barriers to effective system implementation and shared data consumption in cardiology.
Well, that wraps it up for our summaries this week. Now for our feature discussion.
Dr. Carolyn Lam: We are having a truly global conversation today on a really global problem. That is hypertension. From Canada, we've got Dr. Ernesto Schiffrin from McGill University, from Europe we've got Dr. Giuseppe Mancia from university of Milano, from the United States we have Dr. Wonpen Vongpatanasin from UT Southwestern, our dear associate editor and regular voice on this podcast, and then of course from Asia, that's me. You know what we're talking about? It is the global impact of the 2017 ACC/AHA hypertension guidelines. So many novel aspects about these guidelines, including new definitions of hypertension and it's stages, new thresholds and goals of treatment, consideration of the global risks and treatment decisions, addition of classes of recommendations and levels of evidence. So much to talk about, and let's start right now.
Wanpen, you were the brainchild of suggesting these global perspectives. Perhaps say a few words about the ACC/AHA new guidelines first.
Dr. Wonpen Vongpatanasin: Yeah, so I think that this is the guidelines that actually incorporating the more recent evidence and trials, particularly SPRINT, and applying this into the threshold and the blood pressure goal across the board. There's three comprehensive guidelines, and obviously ... The first time, the threshold was lower across the board, and that leads to a lot of discussion and concern and trying to see how we're implementing this or is it appropriate to all the population? Particularly not just in the US and around the world. I guess that leads to us reaching out to many hypertension leaders across the globe and really get very interesting and very insightful feedback from the global experts, two of which is on podcast today. I'm really thankful and excited to have some more in depth insight from them.
Dr. Carolyn Lam: Yeah, exactly. The buzz has really been worldwide, I can see that even from where I'm sitting here in Asia. But maybe Ernesto, I'm just gonna jump straight to the core questions. How are these guidelines different from the hypertension Canada guidelines, and frankly do you think that the ACC American guidelines are going to impact hypertension care in Canada?
Dr. Ernesto Schiffrin: Well, there are quite a few differences. The definition of hypertension remains the classical one in Canada. We have different thresholds and goals, and interestingly, the hypertension Canada guidelines have adopted a SPRINT-based recommendation for high cardiovascular risk patients in contrast to the AHA/ACC hypertension guideline. Although it has intensified the goals for treatment, it has lowered ... Has introduced as you mentioned a category of elevated blood pressure, a new definition of hypertension equal to or above 130 over 80 in contrast to ours equal to or above 140 over 90. It has not really introduced a SPRINT-based recommendation. As well, I think that one of the major questions remains the measurement of blood pressure. In Canada, we have adopted the AOBP, the Automated Office Blood Pressure measurement, at least for high risk, SPRINT like individuals. In the AHA/ACC hypertension guidelines, there is emphasis on standardized blood pressure measurement, but the SPRINT-like measurement of blood pressure has not been adopted.
Dr. Carolyn Lam: Very interesting. In Canada, with the AOBP, how do you translate that? I suppose you estimate it as lower than what would otherwise be labeled?
Dr. Ernesto Schiffrin: That is indeed a problem, because the evidence for the relationship between the AOBP carried out in the absence of a health care professional and the standardized oscillometric measurement, or the osculatory manual measurement, is unclear. The evidence is weak. So we have not really provided a guideline or recommendation with respect to these differences.
In contrast, AHA/ACC provides at least a pragmatic expert-based recommendation on what the differences are between office blood pressure and out-of-office blood pressure measurement. But, as I mentioned, there is no recommendation regarding the SPRINT-like measurement of blood pressure, and that's important because there may be major differences in the order of ten or even 15 millimeters of [inaudible 00:13:32] systolic blood pressure. However, as I see it, the committee for the ACC/AHA hypertension guideline has adopted a prudent and pragmatic approach, and actually simplified thresholds and goals to 130 over 80, and in my view this is a prudent approach.
Will it impact Canada? I think in Canada, most physicians follow the hypertension Canada guidelines, and they are recommended as best practice by governments across the country, provincial and federal. I think that physicians will be aware, but will still carry out their practice following the hypertension Canada guidelines.
Dr. Carolyn Lam: I like that. Aware but perhaps not so practice-changing in Canada. Let's shift to Europe though. Giuseppe, do you agree with that? How do you think these American guidelines may impact physicians in Europe?
Dr. Giuseppe Mancia: The American guidelines have been received with interest, lots of interest. But also there has been some criticism. For example, the question of the SPRINT [inaudible 00:14:55], you read the question of how blood pressure was measured as professor Schiffrin mentioned. It was measured at least in large number professions, why they were [inaudible 00:15:10], I'm not sure. This means that values have lower worth than those obtained by conventional office blood pressure measurement. How much room is still debated, but it could be 10, 15 millimeter mercury, which means that you could compare these SPRINT-like values to conventional office blood pressure values. Probably the SPRINT values are not much lower than 140 millimeters to the mercury systolic.
Then there is the question that can SPRINT mutually [inaudible 00:15:50] at the start. Most of them with two hypertensive charts. So if it's difficult to decide the bounds of threshold to treatment, lower these pressures to the high-low of blood pressure range, less than 140 millimeters mercury systolic when you have patients already treated, because their original blood pressure was probably higher than 140 millimeters of mercury. This [inaudible 00:16:15], however there are other data suggesting that, at least in high-risk individuals, one might indeed start treatment when blood pressure is in the 140 millimeter of mercury. You'll see what the European guidelines will recommend ... They are going to be published in June ... But perhaps this fraction of the population will be a candidate for treatment.
One last point, however, collecting the data from SPRINT is what you wish for in this regard, is that there should be a definite reduction in the threshold blood pressure for treatment in the elderly. In Europe, this was about 160 millimeters mercury based on randomized trials but probably in the future it will be about 140 millimeters mercury. So a large fraction of the elderly population will be involved in [inaudible 00:17:14].
Dr. Carolyn Lam: You know a question I always get though, is what about the side effects? We talk about the benefits of lowering it further, but what about the side effects. I don't know, does anyone have any thoughts on that?
Dr. Ernesto Schiffrin: I would say that, when you look at SPRINT, although there were increased side effects in the intensive treatment group, actually side effects were relatively rare. Some of them were important, such as acute renal failure and hyperkinemia, and so on, and other electrolyte abnormalities and syncope. But they were rare, and when we are recommending intensified treatment for the elderly, for example, which is SPRINT based in the hypertension Canada guidelines, we do say that this approach should be a gentle and progressive one, very aware that particularly in the elderly orthostatic hypertension may occur. One has to be very careful about this intensification of treatment, but yet we believe that if using automated office blood pressure measurement unobserved, you are able to reach lower blood pressures and they are well tolerated around or below 120 systolic, this will benefit these patients as shown in the SPRINT trial.
Dr. Carolyn Lam: Yeah, indeed. That's very nicely put, and just brings up the gaps that we still need to answer, like the way blood pressure is measured, standardization. We may be accounting more about risk versus benefits, patient subgroups. Wanpen, have I missed out anything else? What is the other buzz that you've heard?
Dr. Wonpen Vongpatanasin: I think that we really need to do a better job in measuring blood pressure in basic clinical practice, particularly in the US where we allow only 20 minutes to see your follow-up patient. I don't think that it will be possible to do an AOBP in the US, but I think one thing that makes the issue a little bit murkier is the SPRINT group. I actually just had an abstract presentation at the last HA meeting, that said only half of that site measure in the intended way on AOBP.
Actually, at UT Southwestern we also SPRINT site and we actually did not use AOBP, and when that stratified the treatment side by using AOBP versus non-AOBP, the outcomes was still the benefit of intensive blood pressure reduction for what it's worth. I think that the AOBP story is still controversial, but I think that I agree that we hardly have patient, sit down quietly, for five minutes before we do the measurement. I think that's first and foremost, we need to be able to do that, and do at least two measurements. We'd be lucky if we'd get one measurement after sitting down immediately, that's what we usually get in clinical practice. I definitely agree with Dr. Schifferin that when we ... Particularly the elderly, we have to be careful about orthostatic hypertension. Particular in the SPRINT trial, they actually exclude anyone who had standing systolic blood pressure less than 110. These people who are high risk of having [inaudible 00:20:35] never get into those trials to begin with.
Dr. Carolyn Lam: I can't thank you enough, everyone, for joining me in this chat around the world. It has been a learning conversation for me, as I'm sure it has been for our listeners as well.
Listeners out there, you've been listening to Circulation on the Run. Thank you for joining us today.
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 Centre and Duke National University of Singapore. This week’s issue is the Go Red for Women issue, my favorite discussions of the year happened during this podcast.
Today, I am so delighted to have with me, our Editor-in-Chief himself, Dr. Joe Hill, from UT Southwestern, as well as, of course, the editor that made this issue possible, Dr. Sharon Reimold, also from UT Southwestern. Joe, would you like to tell us a little bit about this year’s Go Red issue? From the birds eye view.
Dr. Joseph Hill: Well Carolyn, I share your enthusiasm. This is our second annual Go Red for Women issue and it is fantastic. It has generated great interest in the community. We had a number of papers coming in, unsolicited. Our frame of reference-type content. Original research articles. State of the art.
We clearly touched a nerve with this issue. As we will discuss further, we shine a bright light here on some of the very best science, focusing on sex-based differences in the biology of heart disease, the presentation of heart disease, how women function, and are treated in the academic environment. The ways in which they are impacted by psychological stress. It's an absolute bonanza of science, in this issue.
Dr. Carolyn Lam: You took the words out of my mouth. It is a bonanza issue. I mean, we had seven original articles. Lots of new stuff, but lots of good, important papers on plain old ischemic heart disease. What I really liked was that, three of these original papers focused on myocardial infractions, in the young, and their risk factors, prevention, and so on. Sharon, shall we go through those? I mean, there was the one on genetics, lifestyle, and LDL in young women.
Dr. Sharon Reimold: That would be great. That manuscript looked at, sort of, a distribution of lipids, in women, that would have otherwise expect to be healthy. They sorted them out by individuals that had extremely low LDL levels and those that had high LDL levels. They pointed out that the individuals with high LDL levels. Ended up having hypercholesterolemia heritable, but they also found genetic variance of related to those with low LDL levels. I think this manuscript points out the importance of screening younger women for lipid disorders and incorporating those data into their clinical management.
Dr. Carolyn Lam: Absolutely. Then, there was that paper that, again, talked about young women experiencing myocardial infarction, and the sex differences in their presentation, and perception. That was super cool. From the Virgo trial.
Dr. Sharon Reimold: There are several other papers, that are published, demonstrating that women tend to have multiple symptoms when they present with symptoms of ischemia. That's true for both myocardial infarction, as well as for other unstable syndromes. They certainly have more symptoms than men.
But what was very interesting about this particular paper, is that when women presented with multiple symptoms, providers were less likely to think that the symptoms were due to a cardiac etiology. So even when women are trying to tell their providers what is going on, sometimes, they're not taken seriously, because they have multiple symptoms. So I'm hoping that this resonates with our providers, clinical providers, and we think about this. Whether we're cardiologist, or emergency room providers, or even EMTs.
Dr. Carolyn Lam: Exactly. Then, the third original paper in these young women, kind of scary, mental stress induced myocardial ischemia.
Dr. Sharon Reimold: Right. So there's been a lot of interest in the myocardial infarction without obstructive coronary disease, in the last year or two. Because a lot of those individuals, even thought, they don't have typical atherosclerotic pathologies, they don't have good outcomes. So this article looks at the role that mental stress plays in inducing ischemia, by EKG, in these individuals.
I think we still need to understand more about how this contributes to the biology, and outcomes, in these individuals. Also, get a better understanding if this is also true in older women, who have ischemic heart disease.
Dr. Carolyn Lam: Exactly. You know, but speaking of the older women, it's not like the issue left out the older women this time either. I did think that the study on the metabolic predictors of incident ischemic events, in postmenopausal women, was really interesting, as well. Basically, the authors identified a cluster of novel metabolites, that were related to oxidative stress, that added to. you know?
They weren't correlated with the traditional biomarkers. Really suggesting that there may be a whole area of metabolites, and other biomarkers, that we may be needing to check, and to understand better, for risk prediction. At least, in older women. But, of course, in men as well. Then, finally, there was the data on sex differences from the STICH trial, on surgical revascularization. What did you think of that one?
Dr. Sharon Reimold: Well, I thought that this was a very important addition to the cardiology literature. Because we are accustomed to thinking of women as having poor outcomes, after they have cabbage revascularization surgery. Certainly, the STICH trial enrolled patients who were more sick than the average patient, with their underline LV dysfunction. They found that sex did not influence the outcomes in this trial.
So the importance of that, for the medical community, is obviously we should not consider sex as a barrier to sending women to surgery, even if they're at high risk, because they can have equally good outcomes.
Dr. Carolyn Lam: Exactly. Important message. Important paper. Then, moving from ischemic heart disease. We also had a paper focusing on stroke, which I thought was a really intriguing one, talking about atrial fibrillation, and questioning if being a woman is a risk modifier, or a risk factor. Do you want to elaborate on that one?
Dr. Sharon Reimold: So instead of the using the CHA2DS2–VASc algorithm they use the CHADS2-VA program and then looked to see how well that predicted risk, and how much the S and C, the gender actually influenced outcome. I think this is an important issue. I'll say it's for women, perhaps. because as a woman, you know, without doing anything, you start out with a risk factor of one. Then, once you get to a certain age you have a risk factor of two. That's even for somebody who has no other disease processes.
Dr. Carolyn Lam: Yeah.
Dr. Sharon Reimold: So I think it's a little different way to look at how the risk is modified. They propose that if your CHADS2-VA score is two, or greater, certainly, your risk goes up if you're also female. They propose, then, that you would treat those patients more intensively. It's just a little twist on the CHA2DS2–VASc and maybe will provide us different ways to refine our knowledge about outcomes in atrial fibrillation.
Dr. Carolyn Lam: Yeah. I love that paper, too, because it's quite different from the papers that we had in the first Go Red issue. Isn't it? But in the first Go Red issue, we had lots of papers on pregnancy. The current issue certainly has those papers as well.
Dr. Sharon Reimold: Yes. There are increasing number of pregnancy related complications. Both maternal, and offspring, complications that predict increased cardiac risk, down the line. This issue has a series of women who had, had preeclampsia during pregnancy, and found that 17% of their women had a coronary artery calcium score of greater than 95th percentile. While that doesn't entirely get you from the biology, in between those two, it at least gives you an idea of where to start going back, and taking a look at what's going on.
Dr. Carolyn Lam: What about the one in rheumatic mitral valve disease? Pregnancy outcomes in women with those?
Dr. Sharon Reimold: So rheumatic heart disease and pregnancy outcomes, you know, we don't see much written about it anymore. because most of the active disease is in certain areas, in the world. But obviously, these women can have symptoms related to their mitral stenosis and/or their regurgitation during their pregnancy, with heart failure being the most common presenting cardiovascular complication. While some of that is much more quantitative, than perhaps, it was in the past, which is useful.
I think that the take-home message from this particular trial is that you need to talk to these patients, and screen them, prior to pregnancy, if possible, to help achieve the best possible outcome. I think that the risk of heart failure was a little bit less than 2% during the trial, which is obviously much higher than the average woman's cardiovascular risk during pregnancy.
Dr. Carolyn Lam: this is still definitely an important issue, in many other parts of the world. I really appreciate that you invited this editorial, that gave that global perspective. The editorial, by Athena Poppas and Katharine French, really beautiful work there. You know, I have to say that one of my favorite papers, in this issue, was that in depth paper, regarding gender versus sex, as a social determinant of cardiovascular risk. I found that so intriguing, the first time I read it, and just love it.
Dr. Sharon Reimold: Social determinants of health is a hot topic, in a lot of different areas of medicine these days. But they point out some really interesting things, that I don't think I had thought about. One is the fact that, when you are a child, you know maybe 10 or 12, that boys are encouraged more to be physically active. Athletics and other sorts of activities. Whereas many girls, don't have the opportunity or are not as interested. Perhaps we set up an abnormal social situation very early in most people's lives.
Dr. Carolyn Lam: Yeah, that represents cardiovascular risk. I know. That stuck out to me too.
Dr. Sharon Reimold: Obviously, how and where people live, as children, can influence outcome. That can be influential for both boys and girls. But I think bringing the idea back to cardiovascular diseases, and risk, are really long term, lifelong processes, that we can make changes in, from a preventative standpoint, even in young people.
Dr. Carolyn Lam: Something we don't usually think about and I just love the way it was presented, so clearly, and I just love it. Now, to an area that really cuts close to the heart. Pun intended. That is the bias in research grants, bias in manuscript authorship. Joe you mentioned that, right from the introduction, I would love your comments on those papers.
Dr. Joseph Hill: The reality, that we all are aware of, is, in many countries, including the United States, 50% of medical students now are female. But as we move through the ranks, into the different subspecialties, and up the career ladder of academic cardiology, we see a thinning of female representation. Arguably, it's been improving, over the last number of years.
But the reality is, that there remains a bias against representation of women, in terms of extra mural grant funding, authorship on high-profile papers. This article digs into that, and analyzes those numbers, takes a snapshot of what it looks like at the present time. In some ways, I believe it's a call to arms on how we must do a better job of recognizing this and rectifying it, going forward.
Dr. Carolyn Lam: Sharon, did you have comments to add?
Dr. Sharon Reimold: Yeah. I mean, I think, I wholeheartedly agree with Joe about those sorts of things. I mean, we see the same types of issues in clinical cardiology as well as in the research components of what we do. we need to figure out how to do this better, so that we all can be productive, going forward.
Dr. Carolyn Lam: You know it's just such a beautiful issue. So rich, in so many ways. Was there anything else you might want to highlight to our listeners?
Dr. Joseph Hill: I might add that Sharon and I kicked off the issue with a brief introduction. Pointing out that the reality is, that one and four women will die of heart disease. Most women don't know that. Most healthcare providers don't know that. Many Cardiologist don't know that.
When you compare that to the realities of breast cancer, it's 1 in 40. It's 10 times different. Now, that community has done a fantastic job. The Susan G. Komen program, in the United States. The pink ribbons, that we see all around the world. That community has done a fabulous job of getting the message out about that grievous disorder.
We have to do better. We have to do better educating ourselves, educating the lay public, about the realities of heart disease in women. 1 in 4, around the world. We also have to do a better job of digging into the science. That's where this issue does an especially good job.
That the reality is that heart disease is different in men and women. It presents differently. It presents at a different age. The way in which women respond to therapies, can differ from men. So there's work to be done, in terms of awareness. There's work to be done, in terms of the underline biology. This is an especially exciting time in this arena.
Dr. Carolyn Lam: I couldn't agree more. I'd add to it, even sex differences and the perceptions about own symptoms, and that of women versus men with chest pain. Then, the whole gender, social element to it. Oh, just so much to discuss, so much to learn from.
Well, listeners you heard it right here. I want you to please send this episode, share it with as many other women as you can think of. Do help us to spread this message, it's such an important one.
Thank you so much, Joe and Sharon, for joining me today. Thank you, listeners, as well. 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.
Today's feature paper is going to cause us to rethink the way we prognosticate patients with pulmonary arterial hypertension following their initial management. Think you know the hemodynamic variables? Well, stay tuned for this discussion coming right up after these summaries:
Our first original paper this week shows for the first time the predictive value of coronary artery calcification progression for coronary and cardiovascular events in a population base study. Authors Dr. Erbel and Lehmann from University Hospital Essen in Germany and their colleagues evaluated several progression algorithms between CTs performed at baseline and after a mean of five years for the risk prediction of coronary and cardiovascular events in a population base cohort of more than 3,200 participants initially free from cardiovascular disease.
The authors found that coronary artery calcification progression added some predictive value to the baseline CT and risk assessment, and even when the five-year risk factors were taken into account. However, the progression yielded no additional benefit when the five-year coronary artery calcification results were taken into account instead of the baseline coronary artery calcification results.
Double zero coronary artery calcification scans in a five-year interval meant an excellent prognosis, which was better than the prognosis for incident coronary artery calcification after five years. Thus, the authors concluded that sophisticated coronary artery calcification progression algorithms may be unnecessary and clinicians can instead rely on the most recent risk and coronary artery calcification assessment.
The next paper demonstrates for the first time cell-specific effects of Smad3 signaling in the infarcted myocardium. Now, in the infarcted heart, Smad3 signaling is known to be activated in both cardiomyocytes and the interstitial cells. In the current paper, co-first authors, Doctors Kong and Shinde, corresponding author Dr. Frangogiannis from Albert Einstein College of Medicine in New York, and their colleagues hypothesized that cell-specific actions of Smad3 may regulate, repair, and remodeling in the infarcted myocardium.
In order to dissect the cell-specific Smad3 actions in myocardial infarction, these authors generated mice with Smad3 loss specifically in activated fibroblasts or in cardiomyocytes. They found that fibroblast-specific Smad3 activation played a critical role in repair following myocardial infarction by restraining fibroblast proliferation and contributing to scar organization by stimulating integrin synthesis.
On the other hand, cardiomyocyte-specific Smad3 signaling did not affect acute ischemic injury, but triggered nitrosative stress and induced matrix metalloproteinase expression in the remodeling myocardium, thereby promoting cardiomyocyte death and contributing to systolic dysfunction.
In summary therefore, these authors demonstrated the cellular specificity of Smad3-dependent actions that stimulate distinct cellular responses in fibroblasts versus cardiomyocytes in the healing myocardial infarction. The implications are that nonspecific therapeutic targeting of Smad3 signaling in pathologic conditions may interfere with both detrimental and beneficial actions. On the other hand, design of interventions with specific cellular targets may be needed for the development of safe and effective therapies.
Good news from the next paper! Genetically predetermined high blood pressure and its complications may be offset by healthy lifestyle. Well, at least, to some extent. First author, Dr. Pazoki, co-corresponding authors Dr. Elliott from Imperial College London and Dr. Tzoulaki from University of Ioannina in Greece aimed to investigate the extent to which lifestyle factors could offset the effect of an adverse blood pressure genetic profile as well as its effects on cardiovascular disease risk.
To do this, they constructed a genetic risk score for high blood pressure using 314 published blood pressure loci in more than 277,000 individuals without previous cardiovascular disease from the UK Biobank study. They scored participants according to their lifestyle factors including body mass index, healthy diet, sedentary lifestyle, alcohol consumption, smoking, and urinary sodium excretion levels measured at recruitment. They examined the association between tertiles of genetic risk and tertiles of lifestyle score with blood pressure levels and incident cardiovascular disease.
They found that adherence to a healthy lifestyle was associated with lower blood pressure regardless of the underlying blood pressure genetic risk. Furthermore, adherence to a healthy lifestyle was also associated with lower risk of myocardial infarction, stroke, and the composite cardiovascular disease at all levels of underlying blood pressure genetic risk. Healthy compared to unhealthy lifestyle showed a 30%, 31%, and 33% lower risk of cardiovascular disease respectively among participants at low, middle, and high genetic risk groups. Thus, these results strongly support population-wide efforts to lower blood pressure and subsequent cardiovascular disease risk through lifestyle modification.
The final paper is an aggregate report from two large randomized trials, which demonstrate for the first time that more potent antiplatelet therapy further lowers venous thromboembolism risk relative to aspirin alone. First author Dr. Cavallari, corresponding author Dr. Bonaca, and colleagues from the TIMI Study Group in the Brigham and Women's Hospital ascertained and characterized symptomatic venous thromboembolism events in more than 47,600 patients randomized in the TRA 2°P-TIMI 50 and PEGASUS-TIMI 54 trials. They evaluated risk of symptomatic venous thromboembolism over time, independent risk factors for venous thromboembolism, and the efficacy of more intensive antiplatelet strategies at reducing venous thromboembolism risk.
They found that the rate of venous thromboembolism in patients with atherosclerosis was 0.3% per year while on treatment with at least one antiplatelet agent. This risk increased independently with the number of symptomatic vascular territories. Furthermore, more intensive antiplatelet therapy with Vorapaxar and Ticagrelor in this case reduced the risk of venous thromboembolism.
These data suggested a relationship between atherosclerosis burden and venous thromboembolism risk. The data also support the inclusion of venous thromboembolism as a prospective endpoint in long-term secondary prevention trials evaluating the risks versus benefits of antiplatelet therapies in patients with atherosclerosis.
Well, that wraps it up for our summaries. Now for our feature discussion.
For our feature discussion today, we are talking about pulmonary arterial hypertension. We've learned so much from registries about prognostication of pulmonary arterial hypertension at the time of diagnosis. But these registries have only provided limited insight into the impact of therapies on long-term outcomes and how we're supposed to use variables after initiation of therapy to determine prognosis.
Well, that gap is being filled by today's paper in circulation. I'm so pleased to have the first and corresponding author with us, Dr. Jason Weatherald from University of Calgary, as well as Dr. Kelly Chin, associate editor from UT Southwestern, to discuss this very important paper.
Jason, congratulations on this paper. Could you tell us a bit more about what you did and why you did it, and what's exciting about what you found?
Dr. Jason Weatherald: This is a study that started during my research fellowship last year when I was spending time in Paris with the group of Professor Olivier Sitbon and Marc Humbert. We started this study based on some other recent papers showing the importance of pulmonary arterial compliance, and some smaller studies that emphasized the importance of hemodynamic variables after treatment initiation and the prognostic importance of that. We wanted to look at the relative importance of pulmonary arterial compliance as well as the stroke volume in the cardiac index in newly diagnosed patients.
We looked at a 10-year cohort from the French registry of patients who had right heart catheterizations at baseline and then after treatment initiation. We looked at prognostic variables, both at baseline and at the first follow-up after initial treatment. The interesting result is that we found that actually pulmonary arterial compliance is not the most important prognostic variable, but it seemed that the stroke volume index, which was calculated from the cardiac index and the heart rate, was the most significant independent predictor of long-term survival from the hemodynamic perspective.
Dr. Carolyn Lam: Kelly, could you help point out why this is so important in clinical practice? You see a lot of these patients. In what way did this paper make you think differently about them?
Dr. Kelly Chin: I think there's a couple different areas that really struck me. The first one was, as you mentioned in the introduction, the importance of post treatment values versus baseline values. This is not to say that the baseline values aren't important because it does still associate with survival and it's very important when choosing therapy, but as PAH therapies have become more effective, we would hope to see that the baseline severity matters less and that, indeed, seems to be what we're seeing here. That also reinforces the importance of serial reassessment to see how your patient is doing and make further decisions for therapy.
The second key finding, I think, is what Jason was just talking about with which hemodynamic measures do we really want to be keeping a close eye on? Here's where, in the stepwise analysis, they found that the right atrial pressure and then, the surprising one, the stroke volume index were the key measures that were associated.
Interestingly, cardiac index fell out of that model. That isn't to say that cardiac index wasn't associated with outcome. It was a predictor in the univariate analysis. But I think when you step back and you think about the comparison between those two, if you have a patient who's maintaining their cardiac index only by becoming tachycardic, they're probably not doing nearly as well as a patient who has a normal heart rate and a normal stroke volume index.
I think this really struck me as something, "Hey, when I'm in the cath lab, I probably need to be thinking about this and reporting it out, so everybody's seeing it right there on the report", which is not something we've been doing.
Dr. Carolyn Lam: Thanks Kelly. That makes so much sense. What I really appreciated about the paper as well is that they gave us practical thresholds through their receiver operating characteristic analyses. Just for everyone to know, the threshold value for stroke volume index was 38 mils per minute per meter square, right? And the right atrial pressure threshold was 9 mils of mercury. These are sort of very important, 38 and 9, and practical to keep in mind. Really appreciate that Jason.
The other thing that struck me is these are just very much saying that right ventricular function is important. Is it not, Jason?
Dr. Jason Weatherald: Yeah, I agree. I think that's one of the interesting insights from the study is that we focused mostly on the cardiac index, but it can be misleading in certain patients like Kelly said who perhaps do respond to therapy by increasing the cardiac index but predominantly through increased heart rate. That can be somewhat misleading if you don't really step back and look at it.
What I found interesting, too, is that when we looked at subgroups of patients who, in the clinic, you generally think are low risk patients who had good six-minute walk distance, very few symptoms NYHA functional class I or II, and had a cardiac index above the current recommended target of 2.5, that there was almost a third of patients with a low stroke volume index in that category and that seemed to be the majority of patients who died over long-term follow-up within five years.
I think that's really telling about the importance of right ventricular function and just looking at the cardiac index itself can perhaps mislead you if you don't take all of those other factors into consideration.
Dr. Carolyn Lam: Yeah, that's just such a great point and important. That even those classified that we would not have picked up as high risk are the usual measures that we look at. If you look at stroke volume index, they still distinguish those who do better than those who do worse. This is something that was also highlighted, I think, in the accompanying editorial, Kelly, that you invited by Lewis Rubin from New York.
Kelly, what do you think are the real take home messages from this?
Dr. Kelly Chin: I think he does make a big point that the functional status of the right ventricle is a primary goal of therapy, and that we should definitely be paying attention to it and that there's more than one way to do this. There's the hemodynamic measurements, there's also exercise capacity and functional class, which really do associate with how well the right heart is functioning, both at rest and exercise. I think he also comes back to the serial measurements and the importance of reassessment.
Dr. Carolyn Lam: Yeah, as you had also so elegantly summarized earlier. But, a quick question to both of you. What do we do now about other measures of right heart function? I mean, magnetic resonance imaging seems to be used increasingly for this. Where does this fall in? And what does this say about the routine clinical parameters that we usually look at, like six-minute walk? Jason?
Dr. Jason Weatherald: I have a couple points on that. Number one, I fully agree and our results are really in keeping with the previous smaller studies looking at cardiac magnetic resonance and showing the importance of the stroke volume on imaging. From personal experience, although MR is wonderful, there's a good population of patients who don't really tolerate MR, especially for serial measurements, and there's other contraindications, so I think hemodynamics will continue to fill an important role and are still useful in the patient where you can't figure out exactly what's going on and why they're getting worse.
At this point, I think it's complementary and certainly I think there's some centers in many countries that don't have cardiac MR widely accessible, especially for serial follow-ups, so I think they're really complementary and that our results support imaging studies.
I would say the next thing about the study is that, in the multi variable models that exercise distance, the six-minute walk distance and functional capacity remained independent predictors, so I think, it just highlights the importance and the robustness of these measures, even though NYHA functional class is subjective, it remains a very powerful predictor at baseline and during follow-up. To me, it speaks to the importance of looking at multiple parameters and coming to a multidimensional assessment of risk and PAH and not focusing on one particular variable for making decisions in the clinic.
Dr. Kelly Chin: I definitely agree with the multidimensional look at a patient function and heart and catheterization. What I was going to say was I also liked, Jason, the use of "complementary" when talking about catheterization and MRI. I see MRI filling a similar niche to echo for many patients. I think if you get an echo and it looks great, heart size is good, heart function is good, I don't see a whole lot of reason to add an MRI, too. We're always routinely doing catheterizations, at least early post treatment, to reassess.
But I do see a role for MRI in some of our patients who are doing not well at all, but we're not quite sure if they're doing poorly enough that it's time for transplant, and I'm trying to decide if the RV is growing or not. It's clearly big, but is it getting bigger each six months that we're looking at it? Sometimes MRI just seems to provide so much more precision than we can get with echo and certainly you're not getting any of those types of measures off of your catheterization.
Dr. Carolyn Lam: Maybe one last question Jason. It's so interesting. What is the future? What are the gaps that you're looking to fill at the moment?
Dr. Jason Weatherald: Ideally, I think it would be a noninvasive way to look at the right ventricle that is cheap, reproducible, and gives us the same confidence that invasive hemodynamics do. Although I find echo is indispensable and MRI is very useful, I think at the end of the day, we all go back to the right heart catheterization and we need to find something that can replace that, but give us the same confidence in what we think we're measuring and that it reflects treatment changes and clinical worsening.
Dr. Carolyn Lam: And Kelly, what do you think should be next steps?
Dr. Kelly Chin: I have to say I really liked this study. I thought it moves us forward in assessment of prognosis for this population of patients in a really big way. It was large and included a large number of measures that were done very carefully. You always want to see replication.
But, what I'd also like to see is the other forms of pulmonary arterial hypertension. You know this focused mainly on the idiopathic PAH patients, so what happens in connective tissue disease, and also what happens late after treatment, because I think we sometimes see a little bit of a different phenotype in patients that we've treated for many years and sometimes hemodynamics have improved, but in different ways than what we see early on with initial therapies.
Dr. Carolyn Lam: You've been listening to Circulation on the Run. 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 today's feature discussion, we are talking about external validation of the DAPT score, a discussion that's going to take us all the way to east Asia, but for now, here are your weekly summaries.
In this week's journal, two studies are presented which compare ductal stenting to surgical shunts in the current era of ductal dependent pulmonary blood flow. As background, infants born with cardiac abnormalities causing dependence on the arterial duct for pulmonary blood flow are often palliated with a shunt between the subclavian artery and either pulmonary arteries. This modified Blalock–Taussig shunt allows progress through early life to an age and weight at which repair or furthermore stable palliation can be safely achieved. However, these modified Blalock–Taussig shunts continue to present concern for post-procedure instability and early mortality.
Duct stenting has emerged as an alternative with potential for greater early stability and improved survival. In the first study, first and corresponding author Dr. Bentham from Yorkshire Heart Centre reviewed data from the National Congenital Heart Audit, comparing the outcomes of 171 neonates who underwent a modified Blalock–Taussig shunt and 83 who underwent attempted ductal stenting, all in the setting of duct dependent pulmonary blood flow between 2012 and 2015. They found that stenting the arterial duct was preferable over the modified Blalock–Taussig shunt in terms of survival to next stage surgery, early post-procedure hemodynamic stability and shorter intensive care and hospital stay. There was a high failure rate both early, with the inability to stent the duct and late, with a greater need for re-intervention on the stented duct compared to the surgical shunt.
The second study originated from four North American pediatric cardiology centers representing the Congenital Catheterization Research Collaborative. First and corresponding author, Dr. Glatz from Children's Hospital of Philadelphia performed a retrospective cohort study reviewing all infants with ductal dependent pulmonary blood flow under a year of age, having either a ductal stent or a modified Blalock–Taussig shunt between 2008 and 2015. Although the observed risks of the primary outcome of death or unplanned re-intervention to treat cyanosis was higher in the surgical shunt group, there was no significant difference between groups after adjusting for patient level factors. Furthermore, after adjusting for patient factors, other outcomes favored the stent group, including fewer procedural complications, shorter intensive care unit length of stay, less frequent need for diuretics and larger and more symmetric pulmonary arteries at last follow up.
These companion papers are discussed in an elegant editorial by Drs. Benson and Van Arsdell from Hospital for Sick Children in Toronto.
The next study tells us that there may be a higher risk of vascular dementia in patient who survive a myocardial infarction. First and corresponding author, Dr. Sundbøll from Aarhus University Hospital in Denmark performed a nationwide, population based study including almost 315,000 patients with myocardial infarction and found that the risk of vascular dementia was higher compared to a matched general population comparison cohort. The risk of vascular dementia was incrementally higher in patients who suffered stroke or developed severe heart failure during the first year after myocardial infarction and in patients who underwent coronary artery bypass grafting. There was no association with all caused dementia, Alzheimer's disease or other dementia sub-types. Take home message is that among one year survivors of myocardial infarction, attention should be placed to persistently higher risk of vascular dementia.
The next study identifies a novel mechanism whereby the RNA binding protein, fragile X mental retardation autosomal homologue one or FXR1, directly regulates gap junction remodeling, leading to dilated cardiomyopathy. Co-first authors Drs. Chu and Novak, corresponding author Dr. Gregorio and colleagues from University of Arizona studied human left ventricle dilated cardiomyopathy biopsy samples as well as mouse models of dilated cardiomyopathy. They found that FXR1 expression was significantly increased in human and mouse dilated cardiomyopathy. Up regulation of FXR1 in the heart altered the location and distribution of gap junctions, subsequently leading to ventricular tachycardia in mice.
Mechanistically, FXR1 associated with intercollated discs and directly interacted with integral gap junction proteins to regulate their expression in cardiomyocytes. Finally, loss of FXR1 in the heart led to dilated cardiomyopathy. Together, these results provide a novel function of FXR1, namely that it directly regulates major gap junction components, contributing to proper cell-cell communication in the heart. Thus, the authors concluded that FXR1 may be a promising target for therapeutic strategies to improve gap junction function in dilated cardiomyopathy.
Well everyone, that wraps it up for our summaries. Now for our feature discussion.
The dual anti-platelet therapy or DAPT score is widely used everywhere to estimate bleeding versus ischemic risk in patients undergoing percutaneous pulmonary intervention. However, very few studies have provided external validation of its utility. Well we have a very important paper in this week's journal that addresses just that in a Japanese population. So pleased to have with us the corresponding author, Dr. Takeshi Kimura from Kyoto University Graduate School of Medicine. Not just him, but also the editorialist for this paper, Dr. Shinya Goto, also an associate editor of Circulation from Tokai University of Japan and last but not least of course, our dear Senior Associate Editor of Circulation, Dr. Laura Mauri from Brigham and Women's Hospital. What an important topic. Takeshi, would you mind to please tell us about your study to start?
Dr Takeshi Kimura: Actually we thought about the utility of the DAPT score provided from the DAPT study in Japanese patient population. In a full cohort of three studies that are conducted in Japan, we compare the risks for ischemic and bleeding risks from 13 to 36 months after a PCI between patients with DAPT score (high-DS) and DAPT score <2 (low-DS) in patients in the Japanese population. We evaluated 12,223 patients. There were 1,344 patients with high DAPT score, 8,279 patients with low DAPT score. The cumulative incidence of primary ischemic end point myocardial infarction or stents from both is significantly higher in the high DAPT score group than in the low DAPT score group.
One of the cumulative incidence of the primary bleeding end point tended to be lower in high DAPT score than in the low DAPT score group, therefore the DAP score has successfully stratified ischemic and bleeding risks in Japanese patients. We've externally validated DAPT score successfully.
Dr Carolyn Lam: Thank you so much Takeshi. Shinya, you wrote an excellent editorial to this paper. Could you let us know why it was so important to validate this in the Japanese population?
Dr Shinya Goto: It's quite homogenous in one way and the other way in the world is heterogeneous. Some may say the risk of thrombotic and the bleeding event in Japanese or East Asia might be different from other regions of world. Dr. Kimura’s paper is the first validation of the DAPT score in the East Asian patient. Original attempts to study didn't include patients from East Asia. This is the real first validation of the DAPT score in that East Asian population. The world is quite homogeneous. It is very important message.
Dr Carolyn Lam: Yes, yes, I agree. Could I just ask maybe a cheeky question. What would you have thought may be any differences?
Dr Shinya Goto: Indeed, previous global trial and also global registry showed relatively low risk of ischemic event. Maybe not many of the US reader doesn't know we are using relatively low dose over anti-coagulant agent for preventing stent thrombosis. Dr. Kimura's paper provides very important insight. DAPT score is predictable for that event but even in the population with lower use of anti-coagulant agent like standard dose of prasugrel in Japan is just 3.75 milligram. Maybe that thrombogenicity in Japanese populations is lower as compared to the global population. Still that’s quite predictable for the ischemic event. That's very important message.
Dr Carolyn Lam: I agree and I have to tell you, practicing in Asia too, I have a tendency to think the bleeding risk may be underestimated by existing scores. We also tend to use lower doses, so it's so important to show objective data such as these. Laura, what are your thoughts coming from the US?
Dr Laura Mauri: Well I think it's very important. I want to congratulate Takeshi, it's a wonderful study, very large randomized data set and very important. I think in the grand scheme of things we do randomized trials, we can't represent every single population in every study. The DAPT study was done in the US, Europe, as well as in Australia and New Zealand, but it's true. We weren't able to also include sites in Asia just from practical reasons. I think it's very exciting to see, looking at this question of the DAPT score in patients in Japan.
I think in general, it matters a lot to understand the generalizability of our randomized trial results across different populations. I think Shinya's mentioned some of the important sources of variability. It may be this great interest in understanding genetics and how they relate in different populations, but there are also clear differences in medical practice across the world. Doing this type of study where one looks at different populations is quite important and I think it's also one of the reasons that circulation in terms of the editors are really seeking to expand the international scope of the randomized trials and secondary studies from randomized studies such as this that really impact patient care across the world.
Dr Takeshi Kimura: I think one of the difference from the DAPT studies in this Japanese closed study is the proportion of the high DAPT score versus low DAPT score is a little bit different. In the Japanese study population, the low DAPT score patients are dominant and also ischemic event risk are lower. However, the DAPT score clearly differentiates that, stratifies the bleeding and the ischemic risks so we should see both the bleeding and ischemic risk and also the difference of absolute event rates in each geographic ischemic population. I think it's important message from this paper.
Dr Carolyn Lam: That is such a great point, Takeshi. In other words, there may be some heterogeneity around the world in baseline risks, as Laura said, baseline practice patterns and I'm talking about baseline both ischemic and bleeding risks. What your paper definitely shows is that the DAPT score however, performs similarly and as we've said so many times, that's such an important message. Shinya, what do you think? What's your message to all the audience out there in Japan and abroad?
Dr Shinya Goto: As Takeshi told me and also how Laura pointed out, if we try to find the difference in the world, there is a difference and if we try to find the similarity, there is a similarity. Dr. Kimura paper shows similarity in the risk factor determining the ischemic and bleeding event. Matched, absolute event risk is low. Background medication is not the same. Majority of the patient taking [inaudible], 200 milligrams a day. [Inaudible] is a bad drug already in the world, but still in Japan, the doctor is still using. Clopidogrel, 75 milligram is also very widely used. The prasugrel dose is just 3.75 milligrams. That is different from the world. Ticagrelor with the dose similar to the world was not successful in the clinical trial in East Asia.
There is a similarity and heterogeneity. Dr. Kimara beautifully demonstrated both in his registry.
Dr Carolyn Lam: Indeed. Laura, looking at this now with these new data, do you think clinical trials should be done any different? Should we be doing multiple small trials maybe in different parts of the world now? Should we power trials to look at regional differences? This trial business is really hard, isn't it?
Dr Laura Mauri: That's a great question. It does come up practicality, whether we should do the same clinical trial in multiple different countries. I don't think it's the six answer, I think that as Shinya, I think, was alluding to, I think that patients responses worldwide are more similar than they are different. That doesn't mean when we plan our trials we shouldn't think about what the differences are and how they might impact the results and whether we might need to make confirmations across the world. I think this study is quite important because it finds the commonality across different populations even though there may be underlying differences that Takeshi mentioned in the baseline rate. I think a similar approach worldwide where we go in with a hypothesis about where things may be consistent or different to determine whether trials need to be replicated elsewhere is useful to have.
Dr Carolyn Lam: Thanks so much, Laura. I don't think any of us could have said it better.
Thank you all for joining me on the show today and thank you ladies and gentlemen throughout the world for listening in today. You've been listening to Circulation on the Run, 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 are going to be discussing the diagnostic conundrum of elevated high sensitivity cardiac troponin levels in a patient with renal disease, but also suspected of acute coronary syndrome. Aha! I bet I caught your attention. A very, very familiar diagnostic dilemma. So stay tuned right after these summaries.
Cardiac allograft vasculopathy is the leading cause of death in patients more than five years post cardiac transplantation. It has been hypothesized that cardiac allograft vasculopathy results from interrupted lymphatic drainage post surgery. Since the donor lymphatic vessels are not inesthimozed to that of the recipient during transplantation, thus the lymphatic system may play a crucial role in the alloimmune response.
Well, these hypothesis are addressed in the first paper in today's journal from first author Dr. Edwards, corresponding author Dr. Wong and colleagues from Kings College, London. These authors use spect CT lymphoscintigraphy in a pre-clinical model. And therefore provided objective quantification of lymphatic flow following transplantation and showed that this correlated to cardiac allograft vasculopathy. They demonstrated that cardiac lymphatic remodeling and lymphatic transport dysfunction post transplant was associated with cardiac allograft vasculopathy and transplant rejection.
They further showed that lymphatic flow was increased during chronic rejection. This in turn may have resulted in enhanced trafficking of antigen presenting cells to the local draining lymph nodes in an augmented alloimmune response. Now although the cause and effect of this phenomenon could not be fully established, these data provided the impetus for the investigation of lymphangiogenesis inhibition as a means to dampen chronic rejection.
The absorb bioresorbable vascular scaffold is known to completely resolve within three years after coronary artery implantation. However, what is the safety and effectiveness of these bioresorbable scaffolds during this critical three year period. First author Dr. Ali, corresponding author Dr. Stone and colleagues from Columbia University Medical Center performed an individual patient level meta analysis of the four randomized absorb trial and demonstrated that compared with metallic everolimus eluting stents, the bioresorbable vascular scaffold had higher rates of target lesion failure and device thrombosis cumulatively to three years and between one and three years. Multi-variable analysis identified the number of treated lesions, current tobacco use and previous cardiac interventions as independent predictors of three year target lesion failure. Whereas diabetes was predictive of three year device thrombosis in bioresorbable vascular scaffold treated patients.
The next paper reported the three year follow up of the FAME 2 trial, which compared PCI guided bi-fractional flow reserve with best medical therapy in patients with stable coronary artery disease to assess clinical outcomes and cost effectiveness. First and corresponding author Dr. Fearon and colleagues from Stanford cardiovascular institute showed that major adverse cardiac events at three years were significantly lower in the PCI group, compared with the medical treatment group. This difference was primarily as a result of a lower rate of urgent revascularization. Mean initial costs were higher in the PCI group, but by three years, were similar between the two groups. The incremental cost effectiveness ratio for PCI compared to medical therapy was more than $17,000 per quality adjusted life year at two years and $1,600 per quality adjusted life year at three years. Thus the authors concluded that percutaneous coronary intervention in patients with stable coronary artery disease and at normal fractional flow reserve may be advantages compared to with medical therapy alone, because it results in improved clinical outcomes and quality of life at no increased cost by the end of three years follow up.
The next study shows for the first time, that pioglitazone may prevent stroke as a single stand-alone outcome. Today's paper by first author Dr. Yaghi, corresponding author Dr. Kernan from Yale School of Medicine and colleagues was a secondary analysis of the iris trial, which showed that pioglitazone reduced the risk for a composite outcome of stroke on myocardial infarction among non-diabetic patients with insulin resistant and a recent stroke or transient ischemic attack. Now, the current planned secondary analysis used updated American Heart Association 2013 consensus criteria for ischemic stroke to examine the effect of pioglitazone on stroke outcomes. The study found that pioglitazone reduced the risk by 25% by five years, with absolute rates of 8% with pioglitazone versus 10.7% with placebo. Pioglitazone reduced the risk for ischemic strokes, but had no effect on the risk of hemorrhagic events. These findings add to the evidence that pioglitazone may be a potent therapy for vascular disease risk reduction and may help inform shared decision making by providers and patients for the use of pioglitazone after ischemic stroke or transient ischemic attack.
Well, that ends it for our summaries. Now for a feature discussion.
The cardiac troponins have really revolutionized cardiology. We use them in of course the diagnosis of myocardial infarction and in fact the recent European Society of Cardiology recommendations say that the rapid zero and one hour triage algorithm for rule in or rule out of non STEMI should use high sensitivity troponins and interestingly irrespective of renal function. Now this latter point has caused some confusion, some questions, since we all know that patients with chronic kidney disease frequently have higher or increased levels of cardiac troponins, especially since we now can detect them with the high sensitivity essays. And this is even in the absence of an acute coronary syndrome.
Well, this week's journal contains two papers that address this topic so well. And I am delighted to have with us the corresponding author of the first paper, Dr. Christian Mueller from University Hospital Basel in Switzerland and the author of the second paper, Dr. Nicholas Mills from University of Edinburgh in Scotland. For the more, we have Dr. Torbjorn Omland, associate editor from University of Oslo in Norway.
Lot's to talk about. Christian, could I start with you? Could you say in your own words the rationale for looking at this vulnerable population and then perhaps describe what you did in your study?
Dr. Christian Mueller: I'm very thankful that Circulation shed a lot of light on the population of patients with renal dysfunction, because both as a clinician and as a researcher, I'm definitely convinced that they merit a lot of our attention for several reasons.
So first, it's important to be aware that the incidents of acute myocardial infarction among patients presenting with acute chest pain is much higher in patients with renal dysfunction, as compared to patients with normal renal function. And second, atypical clinical presentations also are more frequent in patients with renal dysfunction. Then possibly third, the ECG of course also a mandatory tool in our assessment is more often showing unspecific signs that may mimic or obscure the presence of myocardial infarctions and most of them are related to left ventricular hypertrophy. And in addition, patients with renal dysfunction are more prone to adverse events, both related to cardiovascular medication. For example, anticoagulation as well as our cardiovascular procedures, including PCI. Now again, as both papers have a strong focus on troponin, also cardiac troponin is a bit more difficult to interpret in patients with renal dysfunction related to exactly as you mentioned chronic elevations of cardiac troponin, TNI related to chronic cardiovascular disease.
And I think that's so important to stress, any troponin signal in a patient with renal dysfunction is real and should not be incorrectly attributed to just a problem of impaired secretion by the kidneys.
Dr. Carolyn Lam: So definitely an even greater need to diagnose myocardial infarction accurately in this very high risk population. So tell us what you did.
Dr. Christian Mueller: We assessed this challenging sub group within the APACE study. So APACE is a large international prospective diagnostic study that is run in five countries with 12 centers. And we actually enroll consecutive patients presenting with suspected myocardial infarction. And then all patients get a very detailed workup and then adjudicated final diagnosis. And the adjudicated file diagnosis is done by two independent cardiologists and is based on two enormous extensive sets of data. The clinical data set that has been obtained at the local site and of course includes cardiac imaging and standard troponin testing, ECG data.
In the second set of data that includes the study specific data sets, including serial measurements with high sensitivity carry troponin essay and a lot of details characterization of patients and patient follow up. So this is the reference standard against which the one hour algorithm the European Society of Cardiology evaluated. And the one hour algorithm has been derived and previously validated in overall population. Mainly patients with normal renal function. And so we tried to evaluate the performance of this predefined algorithm specifically in patients with renal dysfunctions.
So among a bit more than 3,000 patients, the prevalence of patients with renal dysfunction was 15%. So we had about 500 patients with renal dysfunction. And the interesting finding from our work is that first the prevalence of N-STEMI was nearly threefold in patients with renal dysfunction as compared to patients with normal renal function. And, fortunately the rule out part of the algorithm regarding sensitivity still works very well. It is, however, the efficacy of rule out that is lower in patients with renal dysfunction, simply because fewer patients really have very low troponin concentration and are therefore ineligible for rule out.
However, as a clinician, the main concern with troponin and renal dysfunction is the rule in part, and specificity. And as you would think, specificity of the one hour algorithm was in fact significantly lower in patients with renal dysfunction. It was still appropriate for therapeutic consequences, but it was lower as compared to patients with normal renal function, so the specificity was 89% in patients with renal dysfunction, as compared to 96.5% in normal renal function.
So the overall efficacy of the algorithm was lower in patients with renal dysfunction, however then when trying to create and derive optimized cut off levels, so all cut off levels optimized for use in renal dysfunction, we didn't really find alternative cut offs that would do a much better job than the official cut off levels recommended in the guidelines. So our conclusion is that in patients with renal dysfunction, the safety of the one hour algorithm still is very high, however the specificity of rule in and overall efficacy are decreased.
Dr. Carolyn Lam: Right. That's beautifully summarized. And also that different cut offs didn't really help to increase the efficacy of this algorithm. And just to clarify to our listeners, I believe you defined renal dysfunction as an estimated GFR of less than 60, which is so beautiful because it's perfectly consistent with the second paper.
Nick, could you please tell us about your study and your take home messages as well.
Dr. Nicholas Mills: So high stakes is our clinical trial that we're conducting across hospitals in Scotland to evaluate the best way to use high levels of cardiac troponin in clinical practice. One of the areas of uncertainty is whether these assets really add any additional value for patients with chronic kidney disease, where troponin concentrations tend to be higher. And the premise of a high sensitive test is that we can measure lower concentrations and improve the sensitivity. But is this just going to create uncertainty for clinicians?
So we evaluated 5,000 consecutive patients for performance of high sensitivity cardiac to put in testing. And those with and without renal impairment. And based upon what Christian, we identified that patients with renal impairment are less likely to have very low concentrations, but that you can rule out myocardial infarction safely in patients with renal impairment. And similarly that those with renal impairment are more likely to have an abnormal troponin concentration at presentation. Around about 40% of all patients have troponins above the upper reference limit. And whilst the specificity for myocardial infarction is lower, type one myocardial infarction or myocardial infarction due to plaque rupture or cardiac thrombosis remains the most common diagnosis in this group.
Finally we looked at one year outcomes. And this is really critical. Because we found that patients with renal impairment were two to threefold more likely to die from cardiovascular disease one year following their presentation than those without renal impairment. And I think that my general experience during these tests in clinical practice is that troponin elevations in patients with kidney disease are often ignored and there's a concern about what they mean, and therefore these patients don't get access to the fantastic treatments we have for coronary heart disease. So our take home message is that high sets of troponin testing in patients with renal disease does have value, it's useful for identifying low risk patients although there are fewer of them, and it performs well as a diagnostic test, highlighting in particular a group of patients that really have poor clinical outcomes.
As a cardiological community, we need to do better.
Dr. Carolyn Lam: What I really love about both or your papers is the consistency in the messages. Torbjorn, I want to bring you in on this. You managed both papers. Such a lovely pair of papers that we're so proud to be publishing and you had also invited an editorial by Dr. deFilippi and Seliger. Would you like to comment on your perspective and perhaps the clinical take home message to our audience?
Dr. Torbjørn Omland: Yes, I think this has been pointed very well out by both Christian and Nick. And I think it's worth recapitulating that renal dysfunction is a major problem that clinicians often try to explain by just lack of renal filtration. But that the closest probably are increased production and underlying cardiac disease. So in the editorial Dr. deFilippi Filippi and Dr. Seliger points also out in these things. Moreover they try to look forward and have made comments to recent studies that showed that in patients with renal dysfunction have different troponin fragments than patients with acute myocardial infarctions.
Dr. Carolyn Lam: I find that so fascinating. And it really, really relates to the field of heart failure and what we are also talking and thinking about with natriuretic peptides and their different fragments and the possible different meanings. And how different essays maybe non specific for different fragments.
Christian, you think a lot about these things. I'm curious, what are your thoughts on this and areas of future work that are very urgent?
Dr. Christian Mueller: I think Torbjorn very nicely addressed this. So the current high sensitivity essays for T and I that we use in clinical practice, they are designed kind of to detect everything in blood that looks like troponin, either T or I, including various fragments. And I think it's a fantastic new avenue of research, trying to find out that the biochemical signatures can be further differentiated and exactly that perhaps different troponin fragments or tricordinate products more prominent in patients having ischemic injuries like treat myocardial infarction, as compared to for example other modes of injuries. So I think that's very nice hypothesis and some early data. But at least from my perspectives and to the best of my knowledge until now, the diagnostic algorithms that we have other ways to approach this in clinical practice. And so it's the higher the blood concentration in patients with acute chest pain, the more likely it's acute myocardial infarction. It's not any chronic disease and again the higher the change from presentation to one hour or two hours, the more likely it's acute as a dynamic disorder resulting in an acute increase in cardiac troponin, as compared to the chronic release patterns typically seen in patients with renal dysfunction.
Dr. Carolyn Lam: Yeah. That's just so fascinating. Nick, we sadly are running out of time, but I do want to give you the last word. The clinical take home message, once again. What do you think listeners should take home that may change their practice, after listening to this podcast?
Dr. Nicholas Mills: I think the key message for clinicians, is that in a patient with suspected acute coronary syndrome and has renal impairment and elevated troponin concentration, serial testing is mandatory to differentiate between those that have chronic myocardial injury due to subclinical heart disease and those that are having acute myocardial injury as a consequence of a presumed acute coronary syndrome. Field testing is critical to inform which treatment path and what investigations we recommend for our patients.
Dr. Carolyn Lam: Wonderful. And to take any elevations seriously, because this is a high risk population.
Well, audience you heard it right here on Circulation On The Run. I'm sure you've enjoyed this. I certainly have. Don't forget to tune in again next week.
Dr. Carolyn Lam: Hello from the American Heart Association meeting in Anaheim. I'm Dr. Carolyn Lam, associate editor from Circulation at National Heart Centre in Duke National University of Singapore and I'm so pleased to be here with the Circulation team led by editor in chief Dr. Joe Hill, as well as with Dr. Laura Mauri, senior editor from Brigham and Women's Hospital, and Dr. Dharam Kumbhani, associate editor from UT Southwestern. Boy, we've got lots to discuss. I mean, I want to just first start with congratulating you, Joe. We have got quite a number of simultaneous publications here at the AHA.
Dr. Joseph Hill: I appreciate that, Carolyn. Don't congratulate me. We have a team that is a privilege to work with. One of the initiatives that we launched right from the start was a desire to foster and shine a bright light on emerging science at the major meetings around the world. Often, that involves simultaneous publication.
I'm proud to say that we have 11 simultaneous publications, a record for us here at AHA. Most of them are clinical trials. A few are clinical science, and two of them are young investigators who are competing in the various different competitions. We reached out to them a few weeks ago and offered them the opportunity to submit to us, of course with no guarantees, and our standard remains the same, but we promised that we would provide them with an external peer review. Two of them made it through the process and they will be simultaneously published with their presentations here in Anaheim.
Dr. Carolyn Lam: Wow, well you heard it. A record 11 simultaneous publications. We've got a lot to talk about. Let me just maybe group the topics a little bit. Let's start with talking about peripheral artery disease. I think there are at least three papers around that area, and then we'll talk about coronary artery disease, and almost focusing more on implementation science, papers, there are two there, and then of course we have to talk about heart failure. Dharam, could you start? Tell us about the FOURIER PAD trial.
Dr. Dharam Kumbhani: Yeah. It's very exciting to have clinical trials in the PAD realm. FOURIER PAD is certainly really well done sub-study of the FOURIER trial. As you remember, this was a landmark trial, which compared a PCSK9 inhibitor Evolocumab in two doses, two placebo. The overall trial was done in about 27,000 patients who were followed for a median of 2.2 years. In this trial, Marc Bonaca and investigators, they looked at the PAD subset, which were about 13% of the total cohort. Now, they specifically set out to look at how patients with PAD, during this trial and very gratifyingly, they also specifically assessed how patients with PAD did as far as limb events, not just cardiovascular events.
At the outset, not surprisingly, patients with PAD had a higher risk of cardiovascular events by, I think it was about 60% higher for the primary end point compared with patients who did not have PAD. There was really no, in fact, modification by PAD in that the benefit of Evolocumab that we saw in the overall trial was preserved among the patients with PAD as well as those without PAD. However, because patients with PAD had higher event rates, the absolute risk reductions were higher in patients with PAD.
Then, these investigators looked specifically at the incidents of major adverse limb events, which is a composite of acute limb ischemia, urgent revasc, and major amputations. What they show is that in the overall cohort, there is a 42% reduction in the risk of these major adverse limb events with Evolocumab compared with placebo. Obviously, the effect is significantly higher in patients with PAD. Although the benefit wasn't noted in the PAD subset specifically, the overall p-value for interaction was negative.
One of the really exciting things about this paper is that just like investigators have shown a monotonic reduction in cardiovascular event rates with LDL reduction, similarly, the investigators show a reduction in limb events, which is dose related and the same way in a monotonic fashion with Evolocumab. I think this is really exciting and I think this will be a very important paper for the field.
Dr. Carolyn Lam: Yeah. Dharam, that was beautifully summarized but once you start talking about the peripheral artery disease and this lack of interaction on effects and so on, I think of the CANVAS trial results that were reported at this meeting too. If I could maybe briefly summarize what the authors did in this circumstance, they looked at the more than 10,000 patients in the CANVAS trial who were randomized into Canagliflozin versus placebo in diabetic patients but this time they looked at whether or not there was a difference in effect with the primary prevention cohort versus the secondary prevention.
Primary prevention meaning those adults who had diabetes and risk factors but no established cardiovascular disease and the secondary prevention were those with peripheral artery disease, for example, and other established cardiovascular disease. The same thing, a lack of interaction, which I think is really important because it was the same sort of idea that the overall risk of cardiovascular events was lower in the primary prevention group. Looking at them as a subgroup alone, you didn't get the p-value that crossed the limit because the power was less in a lower risk group, but the lack of statistical interaction really gives us additional information, I think, that Canagliflozin and maybe the SGLT2s in general may be effective for primary prevention in diabetic patients. What do you think?
Dr. Dharam Kumbhani: Yeah. I mean, I think certainly, very interesting findings along those lines. As you pointed out, the event rates are much lower in the primary prevention cohort. All the confidence intervals overlap one, but because all the p-values for interaction for the three-point maze, the four-point maze, et cetera, one would say that there really isn't a difference between the primary and the secondary prevention subgroups. You would potentially have the same benefit in that subgroup as well.
Dr. Carolyn Lam: Fortunately or unfortunately, in that same study, they looked at the risk of amputations and there was a lack of interaction too for that meaning there was a higher risk of amputations with Canagliflozin versus placebo. That of course is a really hot topic now, isn't it? I just wanted to point out though, when you look at it in the primary prevention group, there are only 33 events. What do you think? It spells caution but further look needs to be done? Yeah. Contrast that with the EMPA-REG outcome PAD analysis. You want to tell us about it?
Dr. Dharam Kumbhani: Yeah. Once the Canagliflozin CANVAS findings came out showing a high rate of amputations with Canagliflozin, the Empagliflozin, the EMPA-REG outcome’s investigators went back and looked at the PAD subset in EMPA-REG outcomes. This was about 20% of the total cohort. I will say that unlike FOURIER, which we just discussed, the ascertainment of amputations was not prospectively defined for this trial and it was really obtained from the CRF forms.
However, having said that, it did not appear that amputation rates were higher with Empagliflozin. They did not break it down by the different doses but one assumes that the benefit is consistent between the two doses that they study. One would imagine the PAD patients would have a higher rate overall, which it was, but even in that group, it was about 6% over three years and there was really no difference between the patients who received Empagliflozin versus those who got placebo.
Dr. Carolyn Lam: That EMPA-REG outcome paper, I mean, interestingly, it was a research letter. Joe, you've been watching this whole field unfold right now and our journal has published so many good papers, including CVD REAL, all in this space. Could you comment on that a little bit and the research letter concept and the fact that we're publishing so many of these interesting papers in this topic?
Dr. Joseph Hill: Well, Carolyn, as you inferred, this field is evolving very rapidly. Now, the interface between metabolic disease and diabetes and heart disease is blurring. Some of these diabetic drugs are really emerging as heart failure drugs, it looks like and so there's a great deal of interest in exploring that and trying to find underlying mechanisms. It's an incredibly exciting time. In parallel with that, we are publishing research letters now for papers where, again, our bar starts with validity. Our bar doesn't change but if it's a story that can be communicated with really one multi-paneled figure and an 800word text, then that is a nice bite-size piece of information that we can get out to our readership. We're publishing one or two a week now. Overall, it appears to be well received and I think it's an effective vehicle for conveying certain types of our content.
Dr. Carolyn Lam: Frankly, it's such a delight to read, isn't it? It's hard to write. I think the shorter, the harder to write but this just goes to show how equally important they are.
Dr. Joseph Hill: Absolutely.
Dr. Carolyn Lam: That we're discussing it here. Well, let's go on to the next topic then, coronary artery disease. Regionalization of the care. I'll say that again, regionalization of the care. Would you like to comment on the two papers that are simultaneously being published? One would be the ACCELERATOR-2 trial. That's in the U.S. Then, a second from New Zealand, the ICare-ACS trial. Slightly different but-
Dr. Joseph Hill: Well, that's exactly right. Often, we know what to do but we don't do what we know we need to do in medicine. The implementation of what we already know is an area of hot research and is an area that's evolving rapidly. These two studies, ACCELERATOR-2 here in the United States, focused on regionalization of the interface between EMS systems and EDs, how to get patients identified in the hospital to their device, whether it's a stent or a balloon pump or whatever it is. The first medical contact to device was the metric and by implementing what we already know, the AHA mission lifeline principles, these investigators were able to optimize this regionalization, so there wasn't so much variability across these 12 metropolitan regions. As a consequence, the time to first medical contact to device was shortened, and there was in fact a striking, maybe even surprising, mortality benefit.
Dr. Carolyn Lam: Exactly. That was striking to me too.
Dr. Joseph Hill: From the street to the lab, another paper from New Zealand that you referred to called ICare-ACS focused on doing a better job in the emergency department with serial ECGs and serial high sensitivity troponins, risk stratification algorithms and they found that, again, by developing these clinical pathways within the ED, they were able to shorten the length of stay in the ED and the length of stay in the hospital.
Dr. Carolyn Lam: Yeah. I thought those were amazing and then also from different parts of the world, really strong public health messages as well. Laura, you take care of these ACS patients right on there. What did you think of these papers?
Dr. Laura Mauri: No, I agree. I think that we've, in the past, focused on science and focused on clinical trials but ultimately, none of that matters if we don't deliver the healthcare to the patient. I think this is just a growing field and I'm glad that we're emphasizing it in circulation.
Dr. Carolyn Lam: Absolutely. If we would now go to another area that is really increasing in prevalence throughout the world. Heart failure, and of course, heart failure with preserved ejection fraction.
Dr. Joseph Hill: Your favorite topic.
Dr. Carolyn Lam: Congratulations, Laura on the paper that you're presenting, that is being presented at this meeting, the REDUCE LAP trial. Could you tell us a little bit more about that?
Dr. Laura Mauri: Sure. Yes, as you know, it's a really challenging field, heart failure with preserved ejection fraction. There aren't a lot of therapies that we have. We really don't have great medical therapy. This study actually looks at a medical device to treat patients. It really is a feasibility study, so it's a relatively small trial, just over 90 patients but it's randomized. We know in the device arena, as in all trials, how important randomization is but also blinding. This was actually a sham-controlled blinded trial really designed to look at this interatrial shunt device in patients who have an elevated wedge pressure.
The REDUCE LAP stands for reduce left atrial pressure. That was the primary endpoint, was pulmonary capillary wedge pressure. This was not only looked at the safety, which showed that the device placement was very safe, but at the same time also looked at the proof of concept that by placing the shunt device, there was actually a reduction in wedge pressure over a period of exercise. It needs to be followed on. It's certainly just the first phase of trials but a pretty good standard with the sham control.
Dr. Carolyn Lam: Yeah, well, congratulations again. I mean, this follows … There was a previous publication of the single arm trial and now, this is the first randomized sham-controlled, and the results are consistent. It's a very difficult trial to carry out. HFpEF patients are notoriously difficult to recruit. Could you tell us a little bit about what it was like successfully completing this trial?
Dr. Laura Mauri: Yeah. Well, we had very enthusiastic centers and principal investigators, Ted Feldman and Sanjiv Shah. I think what it really required in this early phase was sites that were committed to characterizing the exercise physiology. The next stage of rolling this out to a broader number of sites and a larger number of patients to see if there's a clinical effect will really be more focused on the clinical endpoints and quality of life because ultimately that's the goal, is to improve symptoms in these patients.
Dr. Carolyn Lam: What I love about the design and the whole concept, it's so simple and elegant. We almost sometimes forget that HFpEF is heart failure, which means that by definition, there's raised filling pressures. It's hemodynamic at the end and this is just a simple concept of offloading the left atrium. That's so beautiful but it does come with some questions. Every time you mention this to someone, they go, “What about, I don't know, Eisenmenger's syndrome developing later?” The right side, volume overload, pulmonary hypertension, what about atrial fibrillation down the line? How about the safety parts of it?
Dr. Laura Mauri: Right, so the procedural safety was excellent but then I think you raise really important questions and these patients are still in follow-up but looking at the report here at this meeting, there was no pulmonary hypertension in excess in the shunt treated arm. The patient selection was towards patients who had higher wedge compared with right atrial pressure and among those patients, there was no evidence of RV overload. At least at this stage things look good to go on to the next step.
Dr. Carolyn Lam: That's wonderful and exciting. We definitely need a therapy for HFpEF. Joe, would you like to highlight any other trial? We have 11. We've discussed six.
Dr. Joseph Hill: Tonight at the editorial board meeting, we will be saluting these two young investigators who are presenting their work in this competition and simultaneously publishing their work. We've invited these young investigators and their mentor and they will present a short talk to the editorial board dinner. It's an effort to salute and recognize these early career investigators, to congratulate them on outstanding work. We're pleased and privileged to publish it, so I'm particularly excited about that.
Dr. Carolyn Lam: Wow, Joe. That is great. Thank you. I didn't know that was happening either. That's fabulous. Dharam or Laura, any other highlights that you may want to mention in this meeting?
Dr. Laura Mauri: I think that it's just been a wonderful kickoff to the meeting. We've covered, I think, many of the really important trials so it's really exciting to be able to see the work in print.
Dr. Carolyn Lam: That’s great, and to discuss it as well.
Dr. Dharam Kumbhani: Yeah, I agree. This is really exciting and hopefully, we can keep growing from strength to strength every year.
Dr. Carolyn Lam: Yep. You heard it right here everyone. We are going to grow from strength to strength under your leadership and with this great team, so thank you very much for joining us today.
Dr. Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. This week's feature paper takes a deep dive into nitric oxide signaling, that extremely important pathway in cardiovascular health and disease. This time, taking a novel look at genetic predisposition, phenotypic consequences, and therapeutic implications. All that coming right up after these summaries.
The first original paper describes the derivation and validation of a novel model to stratify the risk of death due to circulatory etiology in patients resuscitated from cardiac arrest without an ST elevation MI.
First author, Dr. Bascom, corresponding author Dr. Setter from Maine Medical Center in Portland and their colleagues use the International Cardiac Arrest Registry to derive a novel model termed the CREST Model, which describes an incrementally high risk of circulatory etiology death with an increasing score.
Now, CREST is a simple score with components of C for prior coronary artery disease. R for non-shockable rhythm. E for ejection fraction less than 30% on admission. S for shock at the time of admission. T for ischemic time more than 25 minutes. The authors showed that this CREST tool may allow for estimation of circulatory risk and improve triage of cardiac arrest survivors without STEMI at the point of care.
The next study reports associations between usual sodium, potassium and blood pressure using gold standard 24-hour urinary data collected for the first time among a nationally representative sample of adults in the United States.
First and corresponding author Dr. Jackson from Centers for Disease Control and Prevention used cross-sectional data from 766 participants aged 20 to 69 years with complete blood pressure and 24-hour urine collections in the 2014 national health and nutrition examination survey.
They found that there was a strong direct relationship between higher sodium excretion and higher blood pressure and hypertension. In addition, there was an inverse relationship between potassium excretion and blood pressure and hypertension. When added to the evidence based from longitudinal and interventional studies, these results support clinicians dietary advise to lower sodium intake and increase consumption of potassium containing foods.
The next two studies in this week's journal examine the utility of circulating biomarkers to aid in the diagnosis of acute aortic dissection. As a reminder, the AHA/ACC guidelines published in 2010, proposed using the aortic dissection detection risk score or ADD risk score as a primary screening tool based on scoring the presence of three categorical risks.
Number one, high risk conditions such as Marfan Syndrome, a family history of aortic disease, known aortic valve disease, known thoracic aortic aneurysm or previous aortic manipulation. Number two, The pain features such as chest, back or abdominal pain described as being of abrupt onset severe intensity or ripping, tearing. Number three, the examination features such as evidence of profusion deficit, systolic blood pressure difference, spoken neurological deficit or aortic diastolic murmur and hypertension or shock.
The presence of one or more markers within each of these categorical features is given an ADD score of one with a maximum cumulative score of three if all three categorical features are present. In the first of these two papers in this week's journal, first author Dr. Nazareen, corresponding author Dr. Morello and colleagues from Molinette Hospital in Italy performed the advised International Multi Centers Study, which prospectively assessed the diagnostic performance of standardized strategies integrating pre-test probability assessment and D-dimer in 1,850 patients from the emergency department.
They found that in patients with an ADD risk score above one and D-dimer less than 500 nanograms per milliliter, the rate of acute aortic syndromes was significant at one in 22 cases. Rule out strategies for acute aortic syndromes integrating an ADD risk score of zero or one with D-dimer less than 500 were found to miss only around 1 in 300 cases of acute aortic syndrome.
Integrating the ADD risk score with D-dimer could help to standardize diagnostic decisions on advanced imaging for suspected acute aortic syndrome balancing the risks of misdiagnosis and over testing. The authors concluded that patients at high probability of acute aortic syndrome such as with an ADD risk score above one should proceed to computer tomography and geography or other conclusive imaging irrespective of D-dimer levels. However, in those with an ADD risk score of zero or one, with a D-dimer of less than 500 were possible rule out diagnostic strategies for acute aortic syndrome.
The second manuscript in the present issue suggests that soluble ST2 might be an even better biomarker than D-dimer to rule out aortic dissection. In this paper by first author, Dr. Wang, co-corresponding authors, Dr. Du and Guo from Beijing Anzhen Hospital and Peking University respectively, the authors measured plasma concentrations of soluble ST2 using the R&D Systems assay in 1,360 patients including 1,027 participants in the retrospective discovery set and 330 patients with an initial suspicion of acute aortic dissection and ruled in a prospective validation cohort.
The proportion of acute aortic dissection, this acute chest pain cohort was high at more than 40%. The authors found that soluble ST2 measured using this research grade assay showed higher levels in acute aortic dissection than in acute myocardial infarction or in acute pulmonary embolism. The result suggested that soluble ST2 levels could be useful as a rule out marker possibly even to an extent moderately superior to D-dimer.
A cut-off level of around 35 nanograms per milliliters using the research grade soluble ST2 assay appeared to reliably rule out acute aortic dissection if used within 24 hours after symptom onset with a negative likelihood ratio of 0.01 and a negative predictive value of more than 99%. These intriguing findings are discussed in an accompanying editorial by Dr. Toru Suzuki from University of Leicester and Dr. Kim Eagle from University of Michigan. Well, that wraps it up for our summaries. Now, for our future discussion.
Nitric oxide signaling plays a key role in the regulation of vascular tone and platelet activation. In fact, the pharmacologic stimulation of nitric oxide pathway is emerging as a therapeutic strategy in cardiovascular medicine in many areas including in heart failure preserved dejection fraction.
Today's paper is therefore all the more intriguing because it seeks to understand the impact of a genetic predisposition to enhanced nitric oxide signaling on the risk for cardiovascular disease as a way of informing of the potential utility of pharmacologic stimulation of the nitric oxide pathway.
Intrigued? Well, I certainly and I'm so glad to have with us the corresponding author, Dr. Sekar Kathiresan from Massachusetts General Hospital as well as a familiar voice, Dr. Peipei Ping, associate editor from UCLA here to discuss this paper.
Sekar, could I ask you as an introduction to tell us a little bit more of the general approach of looking at genetic predisposition as a way of perhaps forecasting potential utility of pharmacologic stimulation? Could you tell us a little bit more about that?
Dr. Sekar Kathiresan: Yes. I'm delighted to speak a little bit more about this idea of using naturally occurring genetic variation to understand if a medicine developed against a target is going to work in terms of efficacy and also potentially lead to on target side effect.
As you know, there are lots of variants for mutations in genes that eventually become targets for medicines. Over the last 10, 15 years, there's been an explosion in our understanding of human genetic variation, specifically in genes targeted by medicines.
The idea here is that if there's a naturally occurring mutation in that target gene, you can simply ask what are the phenotypic consequences of carrying that mutation. Also use that information to predict, as I said, the efficacy of pharmacologic manipulation and potentially on-target side effects. This approach has become a very powerful approach.
A famous recent example of gene, PCSK9, where mutation in this gene occur naturally. A lower function of PCSK9 and individuals who carry this mutations have lower LDL levels and lower risk of heart attack. This information has led to the development of medicine that mimic those mutations and those medicines have been proven now to lower LDL as well as lower risk of heart attack, a phenomenon anticipated by the genetics.
Dr. Carolyn Lam: If I understand it right then, with regards to today's paper, the idea is that if a genetic predisposition to enhanced nitric oxide signaling associates with reduced risk of cardiovascular disease, then that would support the hypothesis that pharmacologic stimulation of the nitric oxide pathway would prevent or treat the cardiovascular disease, right? Could you further expand? Because you also did a meditation analysis. How would we understand that?
Dr. Sekar Kathiresan: Let me walk you through the basics of this paper. Our hypothesis initially was a genetic predisposition to enhance nitric oxide signaling would actually affect a range of cardiovascular diseases. Nitric oxide is a well-known molecule, a regulator of a number of important processes; vascular tone, blood pressure, platelet aggregation.
A couple of important genes in the nitric oxide pathway are, one, nitric oxide synthase, the key enzyme that generates NO. Second is a soluble guanylyl cyclase that is a regulatory molecule involved in NO biology. One of the genes that is part of that pathway is called GUCY183, which is basically a subunit of the soluble guanylyl cyclase.
What we did was we looked at those two genes and asked, "Are there naturally occurring variations in those two genes that actually give us a sense that they gain function that they actually activate nitric oxide signaling. It turned out there are two polymorphisms. One in nitric oxide synthase and the other is in the soluble guanylyl cyclase subunit that are essentially gain of function. They're common polymorphisms.
We know their gain of function because the carriers of these DNA variants have lower blood pressure. An indicator that there's enhanced NO signaling. We use these two polymorphisms as an instrument to understand the phenotypic consequences of having lifelong enhanced nitric oxide signaling.
What we looked at was the relationship of individuals who carried both of the gene variants or gained a function and asked whether these individuals what the relationship of carrying the variant was to a range of cardiovascular diseases as well as a range of quantitative traits like blood pressure or kidney function.
We looked at this in extremely large human population samples where genotype and phenotype had been collated. Most important of these samples is a recent study of a population-based cohort study called the UK Biobank, which has involved about a half million people where genotype and have phenotype have been assembled.
What we found was that genetic predisposition to enhance nitric oxide signaling was associated with reduced risk of several important cardiovascular diseases. First, coronary heart disease. Second, peripheral arterial disease, and third, ischemic stroke.
That provide a very compelling evidence that atherosclerotic cardiovascular disease would be lower based on enhanced nitric oxide signaling. What was surprising to us is we also found a couple of other diseases where it seemed to benefit from enhanced nitric oxide signaling namely kidney function and pulmonary function. These were a little surprising to us, but I think it really suggest that NO plays an important role in a range of diseases.
In terms of your question about what aspect of NO biology is leading to be relationship to these diseases, is it simply the blood pressure effect for example or could you actually infer a mechanisms beyond the blood pressure? We looked at that specifically in the context of cardiovascular disease and we're able to show that the protection afforded by the enhanced nitric oxide signaling gene variants, that protection exceeded the amount predicted by the blood pressure change. In fact, by quite a bit suggesting that there are probably non-blood pressure mechanisms that are at play in terms of the protection afforded by enhanced nitric oxide signaling gene variants.
Dr. Carolyn Lam: Peipei, I have to invite your thoughts now. This is such an amazing paper. We had great discussions as an editor team. Tell us your thoughts.
Dr. Peipei Ping: The editorial team as well as the reviewers have been very impressed with the quality of the datasets and the value and detail, the metadata analysis together with the appropriate analytical approach. The study is done in our view in a very careful manner and the analysis was performed through the highest standards.
What we also recognized is the potential impact that this particular study may have on multiple areas of studies, in particularly with their findings, the spectrum of individuals, how they carry nitric oxide signaling trends. You could appreciate that the individual score or genetic score paired with the analysis of the genetic variance that they have done, they see from the mental idea that examine both genetic as well as phenotype of each individual is critically important for medicine to be prescribed in the next step of therapies.
Dr. Carolyn Lam: Building on that thought, Sekar, could I ask you? You found some rare inactivating variance. Are these the patients then you think should be targeted for NO enhancing therapies? What's the clinical implications of your findings?
Dr. Sekar Kathiresan: I think there are two ways to think about the implications of these findings. One is there's just a simple biologic insight, the pharmacologic activation of NO signaling maybe protective beyond pulmonary hypertension. As you know, there are actually compounds in the clinic right now that are pharmacologic activators of soluble guanylate cyclase. Those medicines work in the rare condition of pulmonary hypertension.
our work suggest that those medicines are likely to work in a broader range of indications including atherosclerotic cardiovascular disease, kidney disease and pulmonary function. At a simple level, those experiments, I think, should be looked at. Those indications should be looked at.
Whether we've identified a subset of a population that particularly will respond versus it will be a general phenomenon across a range of different individuals that have impaired nitric oxide signaling, I think time will tell. Certainly, one group to think about would be those who are indigenously deficient in nitric oxide signaling and we did find that there are small subset of patients who have inactivating mutations in these two genes and they have higher blood pressure and increased risk for cardiovascular disease.
It was a pretty rare phenomenon, so very small number of individuals would be relevant there. I'm not sure actually that you necessarily want to limit the potential benefit of NO signaling, enhanced NO signaling to just that subgroup. In fact, my prediction would be that the medicine would be relevant for a very large percentage of the population. That you do not need to limit the potential application of this therapy to just those who carry the inactivating mutations.
Dr. Peipei Ping: I agree largely of what Sekar has discussed. I would add that in situations where genetic information are available with the patients, what the study has offered is fairly clear in the patients where rare variance that inactivate the NOS3 or the guanylyl cyclase off the genes. Maybe a failure it is with a higher systolic blood pressure risk. I'm entirely supportive with the general conclusion that we have come to a time point where NOS outside signaling activation is a critical new element of therapy in cardiovascular health and disease.
Dr. Sekar Kathiresan: Thank you Peipei. Thank you Sekar for taking the time to share your thoughts with us. We are so proud to be publishing paper in circulation. So proud and happy to be chatting about this on this podcast. You've been listening to Circulation on the Run. Thank you for joining us and please 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 featured discussion this week focuses on the new 2017 ACC/AHA high blood pressure guidelines, and the potential impact of these guidelines on the U.S. population. A must listen, coming right up after these summaries.
The first original paper this week provides insights into how extracellular matrix remodeling contributes to in‐stent restenosis and thrombosis. First author, Dr. Suna, corresponding author, Dr. Mayr, and colleagues from King's College London, implanted bare metal and drug‐eluting stents in pig coronary arteries with an overstretch and then harvested the stented segments up to 28 days poststenting for proteomics analysis of the media and neointima.
The authors found significant differences by proteomics in the extracellular matrix of coronary arteries after stent implantation. Most notably, an upregulation of aggrecan, a major extracellular matrix component of cartilaginous tissues that confers resistance to compression. In fact, this study provided the first evidence implicating aggrecan and aggrecanases in the vascular injury response after stenting. This opens a door to consideration of aggrecanase activity as new drug targets that may alter extracellular matrix remodeling in the vasculature.
The next paper tells us that empagliflozin could address a significant unmet need in patients with chronic kidney disease. First and corresponding author, Dr. Wanner, from Wurzburg University Clinic in Germany investigated the effects of empagliflozin on clinical outcomes in patients with chronic kidney disease in the EMPA‐REG OUTCOME trial, where patients with type 2 diabetes, established cardiovascular disease, and an eGFR above 30 at screening were randomized to receive empagliflozin or placebo, in addition to standard of care.
In the current study, prevalent kidney disease was defined as an eGFR of less than 60 or urine albumin/creatinine ratio of more than 300 at baseline. In these patients, empagliflozin reduced the risk of cardiovascular death by 29% compared with placebo, reduced the risk of all‐cause mortality by 24%, and reduced the risk of hospitalization for heart failure by 39%, and the risk of allcause hospitalization by 19%.
The effects of empagliflozin on these outcomes were independent of renal function or albuminuria status at baseline. Furthermore, the adverse event profile of empagliflozin was similar across subgroups by renal function at baseline. Adverse events of particular concern in this population, such as urinary tract infection, acute renal failure, hypokalemia or fractures, lower limb amputations or hypoglycemia were not increased with empagliflozin compared to placebo.
The next study provides mechanistic insights into exercise intolerance in heart failure with preserved ejection fraction or HFpEF. First author, Dr. Houstis, corresponding author, Dr. Lewis and colleagues from Massachusetts General Hospital, investigated the mechanism of exercise intolerance in 79 patients with HFpEF and 55 controls referred for cardiopulmonary exercise testing who were also studied with invasive monitoring to measure hemodynamics, blood gases and gas exchange during exercise.
These measurements were used to quantify six steps of oxygen transport and utilization in each HFpEF patients, identifying the defective steps that impaired each one's exercise capacity. The authors then quantified the functional significance of each pathway defect by calculating the improvement in exercise capacity that a patient could expect from correcting the defect.
The authors found that the vast majority of HFpEF patients harbored defects at multiple steps of the pathway, the identity and magnitude of which varied widely. Two of these steps, namely, cardiac output and skeletal muscle oxygen diffusion were impaired relative to controls by an average of 27% and 36% respectively. Due to interactions between a given patient's defects, the predicted benefit of correcting any single defect was often minor. At the individual level, the impact of any given pathway defect on a patient's exercise capacity was strongly influenced by comorbid defects.
The authors concluded that a personalized pathway analysis could identify patients most likely to benefit from treating a specific defect. However, the system properties of oxygen transport favor treating multiple defects at once, such as, with exercise training.
What are the potential benefits or risks of intensive systolic blood pressure lowering in individuals with a low diastolic blood pressure? Well, the final paper today tells us. In this study by first and corresponding author, Dr. Beddhu, and colleagues from Salt Lake City in Utah, a post hoc analysis of the SPRINT trial was performed. Remember that the SPRINT trial was a randomized control trial that compared the effects of intensive versus standard systolic blood pressure control in older adults with high blood pressure at increased risk of cardiovascular disease. The current post hoc analysis examined whether the effects of the systolic blood pressure intervention differed by baseline diastolic blood pressure.
The authors found that there were U‐shaped relationships of baseline diastolic blood pressure with the primary cardiovascular disease outcome and all‐cause death. However, the beneficial effects of intensive systolic blood pressure lowering on the primary cardiovascular disease outcome in all‐cause death were not modified by baseline level of diastolic blood pressure.
Increased risk of kidney events and serious adverse effects of the intervention were consistent across baseline diastolic blood pressure quintals. Therefore, there was no evidence that the benefit of intensive systolic blood pressure lowering differed by baseline diastolic blood pressure levels.
These findings suggest that the reason for the observed associations of worse outcomes with lower diastolic blood pressure was due to underlying processes, such as increased arterial stiffness that lead to a decline in diastolic blood pressure, rather than the level of diastolic blood pressure per se. Furthermore, lower levels of diastolic blood pressure within the ranges examined in SPRINT, should not be an impediment to intensive treatment of hypertension, at least in those without diabetes or stroke.
Well, that wraps it up for our summaries. Now for our feature discussion. The ACC/AHA guidelines for the management of hypertension in adults has really been a hot topic. Just published this year, and it really updates the seventh JNC report, which was published in 2003. Well, today's feature paper deals directly with a comparison of these two guidelines and how it may impact our practice.
I'm so pleased to have with us today the first and corresponding author of this paper, Dr. Paul Muntner, from University of Alabama at Birmingham and a very familiar wonderful voice, Dr. Wanpen Vongpatanasin, associate editor from UT Southwestern. Welcome!
Dr. Paul Muntner: Hi. Thank you for having me.
Dr. Wanpen Vongpatanasin: Hi, Carolyn.
Dr. Carolyn Lam: Paul, could I ask for you to start by painting the differences between the 2017 ACC/AHA guidelines and the JNC 7? We understand you were part of writing the guidelines, so who better than to draw our attention to the main differences.
Dr. Paul Muntner: I think that the new guideline, the ACC/AHA guideline, it was fairly comprehensive included 15 chapters, so there's a lot of new information in the guideline, everything from a dedicated section on the measurement of blood pressure to aspects of patient care.
The manuscripts featured in "Circulation" in this issue is focused on, in the past, there's different blood pressure thresholds in the guideline for defining hypertension, as well as recommendations for antihypertensive medication treatments, as well as blood pressure goals.
As everyone probably knows form JNC 7, hypertension was defined as a systolic blood pressure greater than or equal to 140 mmHg and/or a diastolic blood pressure greater than or equal to 90 mmHg, versus in the 2017 ACC/AHA guideline, these were lowered to 130/80.
In terms of treatment recommendations, there's really a fundamental shift with the new guideline, where the new guideline focuses not just on blood pressure levels, but also on overall cardiovascular disease risk. So going to the new guideline, people are recommended treatment if their blood pressure is above 140/90 but also there's a group with a blood pressure in the 130 to 139 range for systolic blood pressure, of 80 to 89 mmHg for diastolic blood pressure, who are recommended treatment if they have a high cardiovascular disease risk.
Finally, I'll just finish with this last note is that blood pressure control for people taking antihypertensive medication is now 130/80 so a goal blood pressure for people taking antihypertensive medication is systolic blood pressure less than 130 mmHg, and a diastolic blood pressure less than 80 mmHg.
Dr. Carolyn Lam: That was beautifully explained. Paul, I just really loved table 1 of your paper, and I want to refer our audience to it. It so nicely summarizes the differences between the 2017 guidelines and JNC 7. At risk of oversimplifying, when you compare the two in this approach, it's sort of comparing using a cardiovascular risk in conjunction with blood pressure‐type approach with a blood pressureonly number approach, isn't it?
Dr. Paul Muntner: Right. I think that's a key important piece of the new guideline and really CVD risk is used in conjunction with blood pressure levels to guide the recommendation to initiate antihypertensive medication. This decision was based on a wide variety of data from randomized trials, observational studies, as well as simulation or economic analyses that consistently showed the benefits of considering an individual's overall cardiovascular disease risk and providing effective and efficient treatment for lowering blood pressure.
Dr. Carolyn Lam: Right. And you analyzed the impact of this in the NHANES data in today's paper. Could you tell us a bit more about that?
Dr. Paul Muntner: The U.S. National Health and Nutrition Examination Survey, or NHANES, provides an opportunity to generate national representative point estimates on the prevalence of hypertension and treatment recommendations. So we're able to use data on about 9500 U.S. adults. Each person came in for a clinic examination where they had their blood pressure measured three times, and they were asked about their use of antihypertensive medication. What we found was the prevalence of hypertension, or the percentage of U.S. adults with hypertension according to the new guideline, is about 46%, which compares to 32% according to the JNC 7 guideline, so really a big increase in the prevalence of hypertension of about 14%. However, by using the combination of risk and blood pressure, we're not recommending treatment for everyone with hypertension but rather people with hypertension with very high blood pressure as well as those at high cardiovascular disease risk.
So antihypertensive treatment, pharmacological antihypertensive treatment, is now being recommended for about 36% of U.S. adults compared to 34% of U.S. adults according to JNC 7. The rest of the people with hypertension are recommended nonpharmacological therapies; exercise, diet, alcohol reduction, weight loss for people who are overweight and obese.
Really, it's an opportunity to treat people with pharmacological therapy if they're high risk. Then for people who aren't high risk, there's an opportunity for nonpharmacological therapies, so they can, hopefully, prevent the need for further treatment.
Overall, this equates to about 103 million U.S. adults with hypertension, so it's a very large number. However, only about 82 million of these individuals are recommended pharmacological antihypertensive treatment, so there's a big portion of the U.S. population who have hypertension, have high blood pressure, yet we think would benefit from nonpharmacological therapy.
Dr. Carolyn Lam: Wanpen, could I get you to chime in on what you think of the clinical implications of today's paper?
Dr. Wanpen Vongpatanasin: I think that this paper gives us at least reassurance that although we have 30 million more people with hypertension now, not all of them have to be started on medication right away. But it also put an emphasis on cardiovascular risk assessment, which we as the cardiologist are already doing this on a regular basis. It is a major step forward to incorporate cardiovascular risks as another way to gauge how people should be treated intensively, which we like that aspect of it.
Dr. Carolyn Lam: I agree. I think it's reassuring because most people think, "Oh, my goodness. We have got so much more hypertensives to manage." But then it tells us that a restratified approach really keeps it manageable, I suppose. But Wanpen, did you have some specific concerns or questions?
Dr. Wanpen Vongpatanasin: We look at the people who by JNC 7 calls prehypertension, which it's now some of them turn out to be a stage 1 hypertension. The question I have for Paul is that even though guidelines call for nonpharmacologic treatment first, the guidelines said give a try from three to six months, but what happens after that if they're still not reaching the goal?
Would people on the guidelines propose drug treatment eventually because, as you know, nonpharmacology treatment is easier said than done. Even though you might be able to tackle some aspect of it, but I doubt you can tackle everything; exercise, diet, sodium, weight loss all at the same time in a three to six month period.
Dr. Paul Muntner: It's a great question and it's something that the guidelines really spent a lot of time considering and reviewing the evidence. First, what the recommendation is that we recommend nonpharmacological intervention as you mentioned and the re‐evaluation. If the person's blood pressure remains in the stage 1 hypertension range and they're not a high cardiovascular disease risk, then they are recommended to continue attempts at the nonpharmacological interventions.
I've been asked several times since the guideline has been published, "What, are we supposed to just wait until people become high risk?" And my viewpoint on this is, it's hard enough to get people to adhere to their medications currently, let's be judicious about this, focus on the high‐risk people, and maybe if we can communicate with people that have high‐risk for cardiovascular disease, we can work with patients to improve medication adherence and really focus on the low‐risk people in preventing the need for lifelong therapy.
Dr. Wanpen Vongpatanasin: That's great, I think that's really helpful in clarifying this point. Because even if you say that 30 million doesn't need to be started on the drug right away, that eventually have to be started on drug in six months, I think that doesn't really give us a reassurance but, obviously, we still have to continue to
work on these patients who are on the fence of needing pharmacology intervention.
Dr. Paul Muntner: Right. I think what's interesting here is a lot of people since the guideline has been published have said to me, "Now this is done." I said, "No. Now we're really just starting. Now is the most important part of the guideline, which is implementation." And how are we going to implement the guideline, which, as we were just discussing, isn't just about initiating pharmacological therapy, but it's also about the nonpharmacological therapies as well as medication adherence and all these other issues that are in the guideline, proper measurement of blood pressure, etc.
I think that now is going to be the most important time to really have a big impact on our patients' lives by really using the evidence and now that it's in the guideline, we're using the evidence to direct treatment appropriately.
Dr. Carolyn Lam: Indeed, Paul. Just one thing. Along the lines of implementation, how about the issue of the lower target BP, to treat to? What did your study from NHANES show about that, numbers reaching targets, and do you see that as an issue?
Dr. Paul Muntner: It's an interesting question because the findings from our study found that it's currently over half of U.S. adults according to the new guideline, over half of U.S. adults on antihypertensive medication, have blood pressure above the goal in the new guideline. So in our study, 53% of U.S. adults taking antihypertensive medication had a blood pressure above 130/80. This represents an increase from the JNC 7 guideline of people with blood pressure above 140/90, of course, of about 14.4%. According to our estimates, there are about 8 million U.S. adults who are going to be recommended more intensive antihypertensive medication.
The blood pressure of less than 130/80 is a uniform goal for all people taking antihypertensive medication. This comes from several meta‐analyses that have consistently shown the cardiovascular and mortality risk reduction associated with achieving a blood pressure of less than 130/80. I think there's very firm evidence to stand on.
One interesting thing from the guidelines, it's in one of the tables, and I think it's a very important point to make, is that a lot of people who have above goal blood pressure, according to the new guideline, they're only taking one or two classes of antihypertensive medication. The vast majority of them are not taking multiple classes of antihypertensive medication, so we feel that these therapies can be optimized and we're not going to be pushing people into antihypertensive polypharmacy but rather they can receive substantial risk reductions without really giving them too many additional pills.
Dr. Carolyn Lam: Wow. Really about implementation. Wanpen, did you have any other comments before we close?
Dr. Wanpen Vongpatanasin: Yes, I think that is really interesting to see also with these guidelines how is this going to be embraced to the rest of the world. Actually, prior to this guideline, at least hypertension control rate in the U.S. is better than most countries, European countries, as well as in Asia. But now even lowering the bar, we use the same criteria for the rest of the world, that would be a lot worse control rate than now. I think it will be challenging, not only in this country but throughout the world.
Dr. Paul Muntner: That's a great point. Obviously, these guidelines are U.S. guidelines, however, new European guidelines should be coming out in 2018, is what I've heard. I think that even though these guidelines were developed by the American College of Cardiology and the American Heart Association, the data that we're using really comes from worldwide evidence. The evidence didn't stop at the borders. A lot of the evidence that was used in choosing the blood pressure levels to define hypertension, the blood pressure levels to recommend pharmacological interventions, as well as the blood pressure goals do come from other countries. A lot of data from Asia, Europe, Australia, so I think that the data used in these guidelines should be generalized when it's out of the United States.
I think there may be challenges with implementing these guidelines in different settings, and, obviously, a lot of things will have to be tailored to where they will be implemented. However, the overall goal is to reduce the burden of cardiovascular disease and renal disease related to hypertension and, hopefully, that can be a worldwide goal.
Dr. Carolyn Lam: What a great reminder. It is worldwide data, worldwide evidence for a worldwide problem. Well, listeners, you heard it right here on "Circulation on the Run." Thank you so much for joining us today and don't forget to tune in again next week.
Dr Carolyn Lam: (Music playing)...Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the Journal and his editors I'm Dr. Carolyn Lam associate editor from the National Heart Center and Duke National University of Singapore. Today is one of my favorite podcasts as always because it is the fellows in training podcast.
This is where the center stage and we’re so pleased to have two brilliant fellows with us today. Dr. Tom Ford from University of Glasgow and Dr. Kevin Shah from UCLA and of course joining us today as well is our editor for digital strategies, Dr. Amit Khera. Hi everyone.
Dr Kevin Shah: Hi Carolyn.
Dr Carolyn Lam: Hey Kevin. Since you're there in wonderful bright and sunny California and going to talk about one of my favorite topics HFpEF. Could you please tell yourself and then please tell us also about the paper you chose?
Dr Kevin Shah: I am a third-year general cardiology fellow at UCLA. I have a career interest in advanced heart failure and transplant cardiology. I'm going to be doing a one-year fellowship in that next year at Cedars Sinai in Los Angeles.
The article that I picked to discuss was the Reduced LAP Heart Failure I Trial and it was specifically testing a novel device in a small cohort of patients to see if the creation of intraatrial septal connection in patients with HFpEF can improve their filling pressures as well as their symptoms with exercise.
Dr Carolyn Lam: Yeah so Kevin what about this paper stood out to you?
Dr Kevin Shah: The two biggest things that were impressive to me and that really stood out were 1) this concept that keeps coming up more frequently in contemporary research, which is the idea of using a sham trial. Specifically, in this study they did perform a one-to-one randomized trial. With one of the arms, if they did not receive the actual device, they underwent a complete sham undertaking including headphones in music and blind folding the patient who were not sure if they received the device or not.
I think it's an important concept because it does speak to the placebo aspect of procedures. It tries to really control for that when a patient doesn't know if they received a novel device, and we can still test them and see how they feel after-the-fact. I think that's an important strategy in modern trials.
Dr Carolyn Lam: Kevin, that is such a good point and really quite novel too. So we've discussed this paper before but not quite the aspect that you point out and I couldn't agree more. The REDUCED LAP follows its pilot study results, which was open label single arm right published in the Lancet. So this is a very reassuring results since knowledge sham controlled.
I suppose the lesson comes from other device trials that were sham controlled and then gave maybe slightly different results), right when we're talking about the renal innervation trials before. But you said that there were two points that stood out to you so what was the second?
Dr Kevin Shah: The other will also be endpoints and what they chose to target. It was a small trial but I think it's important in a disease state such as HFpEF to select specific endpoint that really reflect the physiology and pathophysiology and the authors should be commended. I think for selecting primary and secondary endpoint that will primarily focus on hemodynamics as well as symptomatic relief.
I know that they are working toward their stage 3 trial and I think in the vein selection of these type of endpoint. Probably more so than endpoints such as mortality are going to favor this disease state in terms of trying to carve out some sort of therapy that actually make patients feel better.
Dr Carolyn Lam: Great great points. For me to just knowing that a hemodynamic endpoint makes sense, because if we look at the Champion Trial and look at the HFpEF subgroup of the champion trial it also seems to show that if people just treated patients with HFpEF according to a hemodynamic guide and in the champion trial that was the pulmonary artery pressure reading. That actually appeared to keep patients out of hospital. And I have to agree with you that sometimes we forget that has HFpEF is about pulmonary congestion and that the end of the day it is a hemodynamic disease. It is heart failure in other words.
Kevin one last thing what do you think about using this sort of strategy in HFREF?
Dr Kevin Shah: That's a good question I can't say I know at least this device has been studied in this trial like you mentioned in one prior trial that was not randomized. I'm sure it's been at least investigated. I can't say I've seen any literature on it. I like to think that it would make some sense from a physiological standpoint, but I don't know if anyone is actually gone to the task of seeing how the device performs in HFREF.
Dr Carolyn Lam: As I said I think at the end of the day I think they're all part of the same heart failure family. And left atrial hyper tension is kind of the final common pathway. So I agree with you that maybe it's worth considering in HFREF too, but then on the other hand of course and have friends HFREF you've got all this great medical therapy. Well Kevin I really, really appreciate your selection. May I now switch over to Tom? Tom would you like to tell us a little bit about yourself ,and which paper you chose.
Dr Tom Ford: Sure thing my name is Tom Ford. I'm very interested in interventional cardiology, and my career path has been a bit unusual because I did my basic cardiology training in Sydney. And then from there I got a great opportunity to pursue a research degree, a PhD, which I’m currently halfway through. That's what Prof. Colin Berry and Prof. Keith Oldroyd here in Glasgow and that’s a British Heart Foundation Fellowship so it's a great opportunity. I went out for recent WOSCOPS Trial from posthoc analysis. In this is a really interesting study a lot of the readers and listeners will be familiar with the original publication. It was actually published 22 years ago. Published in the New England Journal of Medicine.
The WOSCOPS was a landmark trial that looked at statins for primary prevention. And this is the present analysis that looked at just over 2500 Mills with LDL-cholesterol above hundred and 190 mg/dL. So for those of you listeners in the UK 4.5 mmol per liter so quite the high LDL. They looked at these gentlemen without pre-existing vascular disease. There's guideline recommendation for this group but not much evidence. And what they showed was over a five-year period of follow-up that there was a reduction in cardiovascular death and all cause mortality with this treatment. That wasn't just for the period of the trial because of the study design we were able to get a legacy effect which was noted over 20 years of follow-up. So in summary a trial will show the benefits of statins and primary prevention mortality benefit for people without very high LDL to start with.
Dr Carolyn Lam: Carolyn awesome Tom. I love that she began saying that your into interventional cardiology but you chose an article about medical therapy and the importance of it, the statins. I fully agree with you. Amit did you have some for Tom?
Dr Amit Khera: Sure. First I want to commend you both I don't think you did this on purpose but Carolyn's heart failure HFpEF expert. I'm sure she loved the other trial and I'm a preventative cardiologists. So we certainly love you choices this week. Tom, thanks for the summary. It's an important article and one that we did highlight on the previous podcasts. You know there's so many things to talk about but certainly remind you that we have great data sets around that can answer unique questions that maybe are unanswerable today and I think this is an example of that.
Can you speak to this ideal of pulling an old 22-year-old child as you mentioned and how that provides insights and kind of as a PhD student ways to think about ways to be creative and research?
Dr Tom Ford: One of the reasons I chose this child because it's close to my heart looking at a population in the west of Scotland. Sadly over here we've got too high prevalence of cardiovascular morbidity and mortality. So what this trial speaks to is the benefits of a really carefully planned procedure. I mean these were outstanding researchers that thought ahead of their time, and as a result of their analysis. Over two decades later they are still multiple publications and there's kind of open approach where there's different research groups that have used this data set for number of different outputs.
I think a real outstanding example of what can be done with well-planned study.
Dr Amit Khera: Sounds like were in agreement about how to use a fruitful database and continue to learn from it as time goes on. The thing about this as you pointed out is the LDL above 190 component and what the authors say this is sort of the first clinical trial evidence for treatment. In your view, does this change practices or guidelines? Was this already what we were doing? Does this support what we were already doing, or how does this impact clinical care and guidelines currently?
Dr Tom Ford: I think it's a good point. People will say we were doing this anyways. I think now it's going to be helpful and practical inside the clinic. If you can say to a patient well actually look I know we’re asking you to take this tablet you've not actually had an event but, ultimately we know the natural history of people in your position may well be unfortunately that they’re high-risk, and that there is actually a mortality benefit to be had from these tablets that you don't necessarily want to take but definitely the benefit’s there.
Dr Amit Khera: The neat part as you pointed out also was dual components when they're looking at the on treatments during the trial. We see an improvement in events. What the WOSCOPS investigators have done so creatively over the years is this idea of a legacy affect.
The long-term impact in preventive cardiology – certainly a space for where were going was just looking beyond the short-term. There's obviously problems there too because that was not pre specified people were necessarily on assigned therapies. Tell me when you look at this long-term legacy effect what does that mean to you? How does that add be it the way you counsel patients or how you think about this treatment in patients with high LDL?
Dr Tom Ford: The effect of the statin assumes that all the patients are actually taking the drug. I think there has to be an analysis of these patients in this trial and obviously not everyone was compliant. So I think we can maybe extraopolate that for the that there might be in even bigger effect for those patients that were actually taking the drug. And I think if you were to take it for five year period. Obviously we don't know what happens after that. What we do know is the solid mortality data.
What it speaks to me is that if you take the drug and you are at high risk to begin with then potentially it's plaque stabilization, the pleiotrophic effects of statins that we know are beneficial and the hard endpoints are definitely reduced. That persists over 20 years of follow-up. So I think that’s really a great victory for preventive cardiology as you said.
Dr Amit Khera: That's a great point about biasing towards the know when you have people crossing over and that this may be conservative of what was seeing in the long term. I think that's a really important point. One last question for you. The West of Scotland trial - generations have changed and back then obviously part of it was trial design but LDLs on average were higher. The median or mean in the group was around 192.
If you look when they look above or below that 190. The people below were 178 or so - still pretty high LDL. So it does beg the question you know we have this paradigm of LDL above 190 should be treated regardless. You wonder if that should be 160 or whether the number should be lower. What are your thoughts about that?
Dr Tom Ford: I agree with you. I think it's always a challenge to kinda pass off dichotomous endpoints when you’ve got continuous variable like LDL. It's just a continuum of risk and divided using the figure 190 in the study. In fact the patients with LDL less than 190 they couldn't show statistically significant reductions in all cause mortality. But I think it's again personalization of meds and we may have to discuss the risk with individual patient.
Ultimately we do have to have a firm conclusion. I think in this study the data is quite clear that 190 does seem to be quite robust as the predictor who's gonna get the most benefit.
Dr Amit Khera: Listen I think protection article that you pointed out was close to home and you certainly discuss it very well and provided lots of important insights. And again I think it was an excellent choice and one that was really highlighted in the media as well. I think there was a broad allure to this article. If we make change gears now little bit we've heard about the science part know we want to talk about what it means to be a fellow in training.
I just want to say on behalf Circulation also speak for myself. It's so important for us to involve fellows in training into our activities and you're one of our major targets in terms of impact and goals for the journal. We're so delighted to do this twice a year and were always thinking about other ways we can get FITs involved. I mentioned just a couple of things the American Heart Association has of fellows in training program where people can sign up for free and get online access to the journal.
So I hope all fellows are taking part in that. We're starting a new initiative called FAVES where just like you both submitted articles of interest of the fellows can do the same. On Fridays we’ll post those on social media so these are a few ways that were getting FITS more involved and we really hope to continue that. Let me start by maybe asking Kevin to have a chat with you as much.
Kevin in terms of journals there's some me now we're getting inundated with information. I think that's a good thing. How do you consume the medical literature? There's old print journals; there's the online journal; there's a table of contents your social media tell us a little bit about how you consume the medical literature.
Dr Kevin Shah: I agree. We’re kinda getting to a space where now the amount of information that's coming out is tremendous. I think that finding a strategy to help filter out what appeals to your clinical and research interest is becoming more challenging. For me I'll say print journals are slowly kind of falling off. I don't subscribe to too many of them but they still do come to my doorstep. The main way that I would say I'm getting access to or at least becoming aware of articles that are kinda relevant to where I am in my training and what I'm doing is the social media. Some primarily at least for me is Twitter.
I'll say it's a helpful tool and that I can follow a group of individuals that have a similar professional interest as me and you can almost always rely on the fact that somebody will post an article that becomes relevant to a common interest. So between sharing on social media I think that's the primary way that I'm really catching my eyes to a major journal articles.
Aside from that I still subscribe by email to a couple larger journals and see their weekly or biweekly updates about what's being published. And the last at least in my institution our division chief Dr. Gregg Fonarow; he goes out of his way to send to the fellows and faculty new articles that are kind of pertinent to clinical practice. Which is very helpful for us.
Dr Amit Khera: That's so helpful and you know everyone has their own way of consuming the literature but I certainly appreciate your interest in social media. You know there are some luddites out there that think of it literally as just social and it really has a professional bent to it. Well rapidly you can figure out the most cutting-edge important articles in your field so I certainly appreciate your comments. Tom let me ask you now, at your stage of training. You've had an interesting training path as you said you sort of started as an interventional cardiologist and now you are doing a PhD. There so many different articles in Circulation. We have original research, state-of-the-art reviews. We have these opinion pieces and on my minds and different ones. Tell us a little bit about what articles appeal to you and which other novel formats maybe you'd be interested in seeing.
Dr Tom Ford: I think that the original research articles are great if it's in your chosen field. Obviously this is where we're going to a great deal of detail on specific topics but outside of that I think that the review articles are great form if it's something that’s a common clinical topic to kinda brush up on. Your On My Mind section I think is great because it gives you an opportunity to hear from key opinion leaders in the field. I think it was Morton Kern discussing invasive coronary physiological assessment.
So I think there’s different types of articles that can be quite helpful. To start with the original research ones. I’ll skim through the contents. I'll tend not to read the details if it's not in my chosen field.
Dr Amit Khera: Yeah great point. Obviously they are topical depending on what your main interest area and we always say reading around your field to get a broader perspective in cardiovascular medicine. I think you hit on the point about on my mind ones. We really want people be able to free associate and original article are sometimes more stiff and linear. So we really like those pieces as well. Carolyn we’ll give you second set ask a question or two to for today.
Dr Carolyn Lam: Actually Amit I just wanted to comment. Isn't it so encouraging to hear the variety of approaches and you know Circulation has enough that we’re meeting various different needs. I really wanted to take the opportunity to thank you as editor of digital strategies for just doing so many of these initiatives for Circulation. I think it’s just incredibly important for the Journal to keep up with the times in that sense. Amit, may I be cheeky ask you how do you consume the literature?
Dr Amit Khera: Carefully. You know the neat part in being on the editorial board of Circulation and one of the associate editors we get to see so many amazing papers that come through and I think obviously I get to see, essentially and also my digital strategies role I essentially see every paper that comes through that we end up publishing.
Obviously I get wide exposure to Circulation but obviously beyond that I get all the e-Table of Contents for almost every major cardiovascular Journal. Certainly looking at social media and I tend to find hotspots interventions and other areas and podcasts – let’s not forget podcasts. So there's some great podcasts out there. I know of one.
Dr Carolyn Lam: Oh I love it. All right but just one last question for both Tom and Kevin from me. I honestly would love to know what do you think we could do better or what would you like to see more from Circulation?
Dr Kevin Shah: I guess the question I have for Circulation is there any role or have fellows ever gotten involved in the review process for articles?
Dr Amit Khera: Listen that's really important because you learn a lot from doing that and obviously in institutions similar to ours where if you asked to review a paper you have a fellow contribute. I think you might be asking something sort of more formal and systematic with Circulation. I will say that one of our Circulation journals I believe it's Circ Heart Failure or Quality and Outcomes I'll check. It has a formal program where fellows essentially can be assistant editors if you will.
We have our cardiology fellows here at UT Southwestern involved in that process. And I think part of that process is just an IT issue of how to maintain confidentiality of our papers for our authors but yet still let fellows contribute meaningfully. And also timing because you know papers have cycles where you decide if he should go out for review but it'll come back and you never know when that happens you have to make the next level decision.
Then it goes potentially to a meeting and so being able to make sure that fellows can participate at every level, cause that's where the value comes in. We are certainly interested in learning from what our other Circulation of family journals is doing in that space and definitely an area that we've thought about some fellows contribute but need to do more.
Dr Carolyn Lam: And Tom how about you?
Dr Tom Ford: Just picking up on your point on what the sister journals are doing you know I see the Outcomes Journal is looking at more visual abstracts and video abstracts. You know I think it's really important that we increase the efficiency of learning. What's your take on that?
Dr Carolyn Lam: That is the greatest suggestion. I like first of all your phrase of increasing the efficiency of learning. Amit, I'm going to turf it to you again.
Dr Amit Khera: I'll tell you what's amazing you know when I started this role a bit ago. Both of you are obviously contributing to research and everyone on this call is and I think we forget that in the social media space we don't have a lot of data. Some things sound good or feel good. At Circulation my predecessor Carolyn Fox did a randomized trial called intention to tweet if you haven't read it. And there's a follow-up to that that was published. And essentially by randomizing articles to social media or not there was no increase in the views if you will of the article.
There's always limitations to every study but the point is, as you think about novel offerings, something we struggle or something we’ve seen as an opportunity, what works we tried a few things we tried certain videos and we look at what's the uptake and interestingly some things we thought that would be widely of interest really weren’t. Then other avenues we’ve tried have been.
I love what you said, and as Carolyn also felt, the idea of efficiency of learning. I think we need to do frankly in the social media and journal spaces is to continue not just to innovate but to study and figure out what works and what doesn't to help different learners.
Dr Carolyn Lam: (Music playing)....Thank you very much audience for listening today as well. You've been listening to Circulation on the Run. 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 feature paper today focuses on LDL cholesterol results from non-fasting samples and a personalized novel method of LDL cholesterol estimation that you will surely want to know about. So stay tuned, coming up right after these summaries.
The first paper provides new evidence that RUNX1, a gene intensively studied in the cancer and blood research fields, has a critical role in cardiomyocytes following myocardial infarction. Co-first authors, Dr. McCarroll and He, corresponding author Doctor Loughrey and colleagues from University of Glasgow generated a novel tamoxifen-inducible cardiomyocyte-specific RUNX1-deficient mouse and showed that RUNX1-deficient mice were protected against adverse cardiac remodeling post-MI, maintaining ventricular wall thickness and contractile function. Furthermore, these mice lacked eccentric hypertrophy and their cardiomyocytes exhibited markedly improved calcium handling.
At the mechanistic level, these effects were achieved through increased phosphorylation of phospholamban by PKA and relief of sarcoplasmic reticulum calcium pump inhibition. Thus, these data identified RUNX1 as a novel therapeutic target with translational potential to counteract the effects adverse cardiac remodeling post-MI.
The next paper invites us to consider that some our resource-intensive quality improvement initiatives may not be fulfilling their intended goals or even justify their costs. In this paper by first author, Dr. Kutty, corresponding author, Dr. Chan and colleagues from St. Luke's Mid America Heart Institute, the authors evaluated the association between the implementation of pediatric medical emergency teams and the risk-adjusted mortality at the hospital level.
To do this, they looked within the pediatric health information system for freestanding pediatric hospitals and calculated the annual risk-adjusted mortality rates for sites between 2000 and 2015. A random slopes interrupted time series analysis was then used to examine whether implementation of a medical emergency team was associated with lower than expected mortality rates based on the pre-implementation trends. The authors found that before medical emergency team implementation, hospital mortality rates were decreasing by 6% annually across all hospitals. After medical emergency team implementation, the hospital mortality continued to decrease by 6% annually with no deepening of the mortality slope as compared with the pre-implementation trend for the overall cohort or when analyzed separately within each of the study hospitals. Five years after implementation across study sites, there was no difference between predicted and actually mortality rates.
Thus, in summary, the implementation of medical emergency teams in a large sample of pediatric hospitals in the US was not associated with a reduction in hospital mortality beyond the existing pre-implementation trends. This study's null findings on hospital mortality suggests that either medical emergency teams have no effect on mortality or are being poorly implemented in the real world. These issues are discussed in an accompanying editorial by Joshua Koch and Sandeep Das from UT Southwestern.
The next study tells us that carotid stent fractures are not associated with adverse events. First and corresponding author, Dr. Weinberg from Massachusetts General Hospital and his colleagues reported the stent fracture rate and its association with instant re-stenosis and adverse outcomes in the Asymptomatic Carotid Trial 1, which was a prospective multi-center trial of standard surgical risk patients with severe asymptomatic carotid artery stenosis randomized to carotid artery stenting or carotid endarterectomy. Stent fracture occurred in only 5.4% of patients and there was no association between stent fracture and in-stent re-stenosis or with the primary endpoint, which was a composite of death, stroke or myocardial infarction during the 30 days after the procedure or ipsilateral stroke during the 365 days after the procedure.
These findings suggest that routine surveillance for carotid stent fracture may be unnecessary and, if a fracture is identified in an asymptomatic patient, intervention may rarely be required.
Heart rhythm disorder management procedures are increasingly being performed and the next paper tells us important information on mortality and cerebrovascular events following such procedures.
Co-first authors Lee and Ling, corresponding authors Dr. Mulpuru and colleagues from Mayo Clinic in Phoenix, Arizona, performed a retrospective cohort study of all patients undergoing heart rhythm disorder management procedures between 2000 and 2016 at the Mayo Clinic from all three campuses in Rochester, Phoenix and Jacksonville. Among almost 49,000 patients undergoing a total of above 62,000 procedures, the overall mortality and cerebrovascular event rate was 0.36% and 0.12%, respectively. Lead extraction procedures had the highest overall mortality of 0.21% and the highest cerebrovascular event rates at 0.62%. However, most of the deaths and cerebrovascular events occurred after device implantation procedures due to the sheer volume of device implantation procedures, which represented 48% of all the procedures performed.
The most common cause of death directly related to these procedures was cardiac tamponade, being responsible for 40% of all directly related deaths. This highlights the importance of development of protocols for quick identification and management of cardiac tamponade, even in procedures typically believed to be of lower risk such as device implantation.
And that wraps it up for our summaries this week. Now, for our feature discussion.
Lipid testing plays a major role in our day-to-day management of our cardiovascular patients and fasting samples have long been the standard for assessing LDL cholesterol and triglycerides since fasting is believed to reduce the triglyceride variability and allow for a more accurate derivation of the commonly used Friedewald calculated LDL cholesterol. Well, I think that's an assumption we have taken for granted, I mean, since 1972 when the Friedewald calculation was first proposed, but in this day and age, several clinical guidelines from Europe, Canada and the US have now recommended non-fasting lipid testing for routine clinical evaluations and it's time to re-evaluate perhaps the Friedewald LDL or other methods for determining LDL.
Today's feature paper addresses this issue spot-on and we're thrilled to have with us the corresponding author of a very important paper and he is Dr. Seth Martin from the Johns Hopkins Ciccarone Center for Prevention of Cardiovascular Disease and we also have with us Dr. Anand Rohatgi, associate editor from UT Southwestern. Welcome, gentlemen.
Dr. Anand Rohatgi: Thank you, Carolyn.
Dr. Seth Martin: Thank you.
Dr. Carolyn Lam: Seth, that was a super-long lead up from me, but I just find your paper so intriguing. Could you please paint the background of the idea behind your paper today and the rationale for questioning the Friedewald equation?
Dr. Seth Martin: Yeah, my pleasure. This was the first paper to look at directly fasting versus non-fasting using our new algorithm. To give a little background on the algorithm, we had recognized that the Friedewald equation, which had been the standard for decades as you mentioned, would really become problematic in the setting of low LDL concentrations. In fact, Dr. Friedewald himself and his co-authors said that in their original publication in 1972 because what's subtracted out is the LDL cholesterol and it's not a particularly accurate estimate by their equation, but at the time, it was viewed as acceptable because the concentrations of LDL weren't all that low.
Now, in the modern era, things are different. We treat the lower LDL. We're lucky to have new drugs that allow us to achieve low LDL levels and meanwhile we have many more patients with obesity and diabetes, leading to higher triglyceride levels, so this all means that that estimated component of the equation becomes a bigger part of the equation and that's what spurred us on to say, "Well, cane we estimate that better?" And we were very lucky to have access to a huge data set that had over a million patients and had directly measured VLDL cholesterol as well as triglycerides, so that allowed us to really more specifically address this estimated component of the equation.
To just give the brief details on what the equation does, is we take the original Friedewald equation from what I view is a one-size-fits-all approach where we divide triglycerides by 5 in milligrams per deciliter and now we just match the patient based on their lipid profile using the same data as the Friedewald equation with the more personalized factors, so taking it from one size fits all to a more precision or personalized fit and it's one of 180 different factors that the patient may get matched with and what we've found is that this type of approach is more flexible, so it's going ... as patients triglyceride levels go up in the setting of low LDL and as they go into non-fasting states, this type of approach can adapt to that better and provide a more reliable, accurate estimate of LDL cholesterol.
Dr. Carolyn Lam: That is so cool. It really is. It just makes so much sense in this day and age of proceeding towards personalized medicine, to make sure we apply equations that are personalized, so your paper essentially shows that applying this new equation works better than the traditional equation, particularly in the non-fasting states, right? And for states of low LDL cholesterol or perhaps high triglycerides. Would that be a good summary?
Dr. Seth Martin: Yeah, that's a great summary and this paper ... I'm really lucky. It was led by one of the fantastic Osler medical residents, Vasanth Sathiyakumar, who is going to be a future star in cardiology, I believe, and he did a great job leading our paper, which shows that in the non-fasting state, what happens is triglyceride levels are higher and this means that the Friedewald equation becomes less accurate and I think this has been a little bit overlooked in recent trends where there's been a big push to do more non-fasting lipid profiles, which really is great for patients, more convenient and it makes a lot of sense, but we have to be also, in an era of precision medicine, getting precise data and if we're going to be making clinical decisions based on LDL concentration, we want to make sure we have good information there and what our paper shows is that there should be some level of caution when using non-fasting Friedewald LDL at low levels, but our new algorithm does provide a more robust estimate in that setting.
Dr. Carolyn Lam: Anand, this is begging for the question, "What do you think are going to be the practical implications of this very important paper?"
Dr. Anand Rohatgi: I think the clinical implications are huge and I think that's why we were so excited when we received this, that sort of the potential impact was there. I can tell you personally my clinic is in the afternoon and so it's a struggle to try to get patients to get fasting lipid levels and often they can't do it when they're coming to see me and so the importance of non-fasting lipid levels is clear and what Seth's group has done is showed that we can actually accurately estimate the LDL levels. A lot of people struggle with trying to still calculate the non-HDL levels and, as Seth pointed out, oftentimes when you're non-fasting, the triglyceride levels are higher and the calculated LDL from Friedewald is artificially low, so it's very hard to combine the convenience of just looking at the lipid levels and having sort of a confidence in the actual calculated LDL, so in this case clinicians can have their patients get their lipid levels at any time and with this algorithm that's already being used by major laboratory services will have relatively high confidence that the LDL that they see is very accurate and then they can make a decision based off of that and they can counsel in real time based off of that, so it really changes the ability to engage with patients at any time and is not restrictive.
I can tell you many patients sometimes won't even get their lipid levels for weeks just because they can't arrange for it to be done on a fasting state and so this really liberates patients and it really enhances the doctor-patient relationship, I think.
Dr. Carolyn Lam: I agree, Anand. I like that word that you used, "liberate" the patient. Honestly, I think some of my patients cheat a little too and they don't really fast as they should before their fasting lipids and this is going to be incredibly helpful.
I have a couple of questions for you, though, Seth. In terms of understanding the limitations of what you may have tested in the current study, we all know that with triglycerides in the super-high level of more than 400, for example, the Friedewald equation breaks down. Did you test this with the new equation because I think you excluded this group as well in the current study, did you not?
Dr. Seth Martin: That's correct, yes. Traditionally, the Friedewald equation has excluded folks from calculation who have triglyceride levels, as you said, of 400 milligrams per deciliter or more and the reason for that is that's the setting where chylomicrons are more likely to be present and therefore we're trying to estimate VLDL cholesterol and it wouldn't make sense to do that if there's a lot of triglycerides and chylomicrons.
That being said, we did look at this previously and found that in that setting our equation works quite a bit better than Friedewald, but it's still inaccurate I would say about a third of the time due to the presence of chylomicrons, so it's an area where we should certainly be more cautious in estimating LDL cholesterol if the triglycerides are that high, but honestly in that setting, often the clinical priority is going to revolve around triglyceride lowering and the LDL may not be the most immediate priority for clinical treatment.
Dr. Carolyn Lam: And then just another question, recognizing that our podcast is heard throughout the world, in this day and age of precision medicine, how about accounting for potential ethnic differences, possibly? Did you account for differences in race, gender perhaps in these equations?
Dr. Seth Martin: What we found is that this really is a lipid-dependent phenomenon in terms of the ratio of triglycerides to VLDL in estimating LDL. We previously looked at age and sex and found that they contributed very, very little information to actually explaining this ratio and so I think that it is something that's likely going to be preserved across different demographic groups. I can say to our listeners in places ... in Asia that the equation has been validated over there and so there's some reassurance that even around the world and other places like Brazil, that it is holding up, so I think that largely this is going to be dependent on someone's lipid profile and it is quite simple in that regard, that we don't have to likely worry about too much differences between men, women, older, younger or different ethnicities.
Dr. Anand Rohatgi: I have a question for Seth. As we mentioned, this is an international audience and guidelines do differ on their emphasis on lipid targets now as everyone is aware, some still emphasizing them and others, like the American guidelines, de-emphasizing targets, so Seth, the question i had for you is based off of your work. Where do you see that fitting in with how the different guidelines and societies are trying to emphasize or de-emphasize lipid targets.
Dr. Seth Martin: The amazing thing is we're all ... really have access to the same data. We've worked together throughout the globe to generate clinical trial evidence that guides us as well as all sorts of other type of evidence to guide us in clinical practice, so just on a very broad conceptual level, my hope is that over time with the great exchange of information around the world that we're going to converge more on consensus recommendations and then, of course, there may be needs to adapt those recommendations to different cultures and that can be taken into account, so I'm hoping there'll be a push towards more consensus and as we get our updated American guidelines, it's looking like this upcoming year, I hope that we come into even more harmony with the rest of the world.
I think for a long time we've had this LDL goal in many different guidelines as less than 70, so that's part of the reason our work has focused on that level. The European guidelines have a target level for high-risk patients of less than 70 for LDL and I think what we saw in the recent consensus document on non-statins from the American College of Cardiology was a push to be thinking at that level when the LDL is 70 or above as a time to have a clinician and patient discussion about whether we should be intensifying therapy, so I guess would say the guidelines in my view, and Anand I would be curious of your view, are more alike than different, but I hope they become even more in harmony because really we're all basing our decisions on the same evidence base and I think it can be a bit confusing when we have disparate recommendations.
The same can be said for the issue of recommendations for fasting versus non-fasting guidelines, which have not been harmonized either, but Anand I'd be curious to your thoughts as well on this topic.
Dr. Anand Rohatgi: I would agree with you. I think they're more alike than different. It's just what may be the high level sort of things have come out to the lay public and others, but I agree with you. If you really read them, they're emphasizing risk reduction by the therapies and by controlling the risk factors, in particular the lipid levels, so I think that's where your work is really important and insightful and I think will be incorporated in all of the respective guideline revisions.
Dr. Carolyn Lam: I completely agree and we're so proud to be publishing your excellent work in circulation. Thank you, Seth. Thank you, Anand.
Thank you, listeners, for joining us today. Don't forget to 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 Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
This week's journal features two papers. One a research letter and the second an original article, both focusing on the effect of ionizing radiation on interventional cardiologists. I'm sure that cuts close to the heart, so please stay tuned. Coming up right after these summaries.
The first two original articles in this week's journal describe a metabolic adaptation that is good for the abnormal cell but bad for the patient. This is a shift in glucose metabolism called the Warburg phenomenon where there is failure of two fundamental pathways. Number one glucose metabolism and number two mitochondrial oxygen sensing. This Warburg phenomenon enables a reliance on glycolysis despite an abundance of available oxygen. These two circulation articles uncover new players in the Warburg phenomenon, both in the setting of pulmonary arterial hypertension. One in the pulmonary arterial endothelial cells, and the second in fibroblasts.
In the first paper, first and corresponding author Dr. Caruso and co-corresponding author Dr. Morrell from the University of Cambridge examined the microRNA and proteomic profiles of blood outgrowth endothelial cells from patients with heritable pulmonary arterial hypertension due to mutations in the bone morphogenetic protein receptor type two, or BMPR2 gene, and in patients with idiopathic pulmonary arterial hypertension. They demonstrated that reduced expression of microRNA-124 in pulmonary arterial hypertension endothelial cells was responsible for the dysregulation of the splicing factor polypyrimidine tract binding protein 1, and its target pyruvate kinase M2 or PKM2, which is a major regulator of glycolysis and which contributes to abnormal cell proliferation. Reduced BMPR2 levels were associated with reduced microRNA-124 expression.
In the second paper first author Dr. Zhang, corresponding author Dr Stenmark and colleagues from the University of Colorado studied pulmonary adventitial fibroblasts isolated from cows and humans with severe pulmonary hypertension. PKM2 inhibition reversed the glycolytic status of pulmonary hypertension fibroblasts, decreased their cell proliferation and attenuated macrophage interleukin beta expression.
Normalizing the PKM2 to M1 ratio in pulmonary hypertension fibroblasts by using microRNA-124 over expression, or by PTBP1 knockdown, reversed the glycolytic phenotype, rescued mitochondrial reprogramming and decreased cell proliferation. Finally, pharmacological manipulation of PKM2 activity or treatment with histone deacetylase inhibitors produced similar results. These findings provide new avenues for the treatment of pulmonary arterial hypertension and are discussed in an accompanying editorial by Stephen Archer from Queen's University in Ontario Canada.
The next paper tells us that the addition of ezetimibe to simvastatin in patients stabilized after acute coronary syndrome reduces the frequency of ischemic stroke, with a particularly large effect seen in patients with a prior stroke. First and corresponding author Dr. Bohula and colleagues from the TIMI study group investigated the efficacy of the addition of ezetimibe to simvastatin for prevention of stroke in the IMPROVE-IT trial where post ACS patients were randomized to placebo and simvastatin or ezetimibe and simvastatin and followed for a median of six years.
The current study focused on patients with a history of stroke prior to randomization. The authors found that the addition of ezetimibe to simvastatin reduced the frequency of ischemic stroke with a hazards ratio of 0.79, with a particularly large effect seen in patients with a prior stroke, where the hazards ratio was 0.52, compared to patients without a prior stroke where the hazards ratio was 0.84. Hemorrhagic strokes were rare and a non significant increase in hemorrhagic stroke was observed with the addition of ezetimibe. Thus, the authors concluded that it is reasonable to consider the addition of ezetimibe, a generic lipid lowering therapy with an acceptable safety profile, to a moderate to high intensity statin regimen for the prevention of ischemic stroke in patients with established ischemic heart disease, with or without a prior stroke.
Atrial fibrillation is the most common sustained arrhythmia in hypertrophic cardiomyopathy, but the influence of atrial fibrillation on clinical course and outcomes in hypertrophic cardiomyopathy had remained incompletely resolved. That is until today's paper in circulation. First and corresponding author Dr. Rowin and colleagues from Tufts Medical Center accessed the records of 1,558 consecutive patients followed at the Tufts Medical Center hypertrophic cardiomyopathy institute for an average of 4.8 years from 2004 to 2014.
20% of patients had episodes of atrial fibrillation, of which 74% were confined to symptomatic paroxysmal atrial fibrillation, while 26% developed permanent atrial fibrillation. They found that the timing and frequency of paroxysmal atrial fibrillation events were unpredictable with an average two year interval between the first and second symptomatic episodes but progressing to permanent atrial fibrillation uncommonly. They further found that atrial fibrillation was not a major contributor to heart failure morbidity, nor a cause of arrhythmic sudden death, and when atrial fibrillation was treated it was associated with low disease related mortality, no different than for patients without atrial fibrillation. Finally, atrial fibrillation was an uncommon primary cause of death in hypertrophic cardiomyopathy, but this was virtually limited to embolic stroke, thus supporting a low threshold for initiating anticoagulation therapy.
That warps it up for our summaries. Now for our feature discussion. This week's journal carries two papers that refer to the health risks of ionizing radiation to interventional cardiologists. Yes, you heard me right. You're going to want to listen up. These are going to send chills up our spine, or rather maybe chills into our brains and into our blood according to the papers.
To discuss these two papers I have with us associate editor from UT Southwestern, Dr. Manos Brilakis, as well as the corresponding author of the first paper Dr. Maria Andreassi from CNR Institute of Clinical Physiology from Pisa Italy. Maria, could you start us off by telling us what you found in your research letter?
Dr Maria Andreassi: In our study we evaluated the circulating microRNA profile in interventional cardiologists in order to provide insights into the molecular and the biological situation and the underlying association between occupational low dose radiation exposure in cath lab and the potential long term disease risk. The hypothesis of our study was based on the evidence that the microRNAs are crucial regulators of gene expression. And they have been shown to be dysregulated in many human disease. Moreover, the stability and the tissue selectivity of circulating microRNAs make them ideal biomarkers to explore disease potential clinical disease risk.
In summary, our findings exhibited the dysregulation and the down regulation of acute specific circulating microRNA, the brain specific microRNA-154 and the microRNA-2392. This tells us significantly involved in the deregulation of the three brain pathways and the brain cancer pathway as demonstrated by systematic analysis. In particular, the dysregulated labels so the brain specific microRNA-154 in interventional cardiologists support the notion that the brain damage is one of the main potential long term risk on unprotected head radiation in interventional cardiologists with possible long lasting consequences on the cognitive function.
Dr Carolyn Lam: That is really striking. Brain specific microRNA was shown to be dysregulated in interventional cardiologists compared to controls who were not exposed to radiation. As I understand it, these dysregulated microRNAs can be seen in certain forms of epilepsy and Alzheimer's disease and certain brain cancers and so the concern is very obvious for those of us who are interventional cardiologists. But your study did not actually relate these two specific adverse events. Is that correct?
Dr Maria Andreassi: You're right. Yes. microRNA-154 was first identified as a brain specific microRNA which is involved with inner synapse development and the directly implicated in [inaudible 00:12:15] and memory. Additionally, decreased expression of this microRNA class, was previously reported in several brain disorders including the thymus disease and bipolar disorder. This microRNA has also been shown to be down regulated in several brain cancers such as neuroblastomas. The reduced expression of the microRNA-154 is a predictor of progression and prognosis of human gliomas. This data strongly support it's important role in brain tumors. Our findings are of particular interest in relation the handle exposure to the pathology of the head, the [inaudible 00:13:13] 20, 50 millisieverts. The equivalent to 1,000, 2,000 chest x-rays and can reach a lifetime cumulative exposure around two sieverts for left hippocampus and one sievert for right hippocampus.
Dr Carolyn Lam: That really makes me go, yikes. But Manos, as an interventional cardiologist yourself, what are your thoughts? And also your thoughts please on that other paper that's in this week's journal?
Dr Manos Brilakis: First of all, let me just congratulate Maria Andreassi, she's been one of the leaders in this area and published several papers and this is one of them. It's really important to have these studies because unfortunately we as interventional cardiologists tend to forget about the negative affects of radiation because as you hear, people don't really see them and this can happen many years down the line. And by the time they happen, it's too late. It's really useful to have the studies to bring our attention the importance of keeping the radiation exposure to the patient and to ourselves as low as possible.
The other paper in addition to the one just discussed, is a paper that looks at DNA damage on operators performing endovascular aortic repair. As a preface, these are procedures demonstrated the aortic aneurism repairs which are very intense radiation wise. They are long procedures, fielding can sometimes be challenging for the operator. There is significant exposure of the operator to x-ray. What they did is they measured some markers of DNA damage and repair. Specifically gamma-H1AX and DDR, the DNA damage response marker and the pATM. They measured them in circulating lymphocytes in operators who performed the endovascular aortic aneurism. What they found is that there were significantly higher levels of those markers immediately after those operators performed those procedures. And they did the same thing after x-ray using leg shielding.
That's a very good reminder for us that the x-ray tube actually is not on the top of the table, but the x-ray tube, the generator, of the x-rays is actually on the bottom. Then the x-ray goes through the patient and the detector is at the top of the table and what happens is the x-ray comes from below the patient and gets scattered from the patient and coming towards the operator so actually it's the legs get the higher dose during any sort of x-ray guided procedure. Sometimes we're forgetting importance of shielding the legs 'cause we think the legs, whatever the muscles, the bones, they're fine. But as the study shows, it's not just the muscles and the bones there but the whole circulation blood gets exposed to x-ray in the lower extremity circulation and that can translate to many other potentially adverse events.
Dr Carolyn Lam: Manos, I love that you manage both these papers. What important messages for increase in risk awareness. This was really very, very well accomplished by both these papers. As well by the editorial that you asked for and that was so well written by Dr. Charles Chambers on both these papers. But beyond risk awareness, what I really love is what you brought up just a while earlier about risk reduction and methods that we can take, for example, in the second paper, by Dr. Modoari and colleagues about shielding the legs. What are the implications for example, wearing a helmet or shielding the head for interventional cardiologists? What do you think?
Dr Manos Brilakis: These are very, very good points. The reality is for the head there have been a couple studied that looked at shielding with lead caps or there's some lead free caps that can be worn and also there are radiation protective glasses. However, what was interesting, there was a paper earlier last year that showed that because the radiation actually comes from below the operator that wearing those helmets, although it seems appealing, it is simple to do obviously, it actually did not significantly reduce the dose to the brain and it only partially reduced the dose to the eyes. Though shielding is useful but may not be as good as we think it is.
In my mind, the starting point of all this is the basics of radiation safety which again, sound very simple and we learn about them in the beginning of training, unfortunately what happen is people tend to forget them as time goes by. These are things like don't step on the x-ray pedal unless you need to look at the pictures and that's very common done. People just have this heavy foot syndrome. They keep on x-raying when they don't need to. There's also the important things having the patient as high as possible and the detector as close to the patient so there is not as much distance for the x-ray to travel. Things like using low, not very steep angles so there is not as much radiation because they have to go through less amount of tissue. And there's some technologies actually coming along there's some technologies that focus the radiation beam only specific areas. And cut the overall dose. And there are x-ray machines that also can have much less radiation overall for the patient and the operator. As you said, having good shielding habits is very important.
Dr Carolyn Lam: Yeah, that's exactly it. That risk awareness should lead to action. I'm just curious, who do you think should primarily take hold of these risk reduction and safety procedures and the enforcement and so on? Us as a community, but what do you think of the role of things like professional societies, quality improvement programs, FDA even?
Dr Manos Brilakis: It's a great point. What we hear here Maria's comments on this as well. But my feeling is absolutely societies are very important for leading these efforts and they do have actually guidelines. There's procedural guidelines for radiation protection. But the end of the day it's the individuals themselves, the operators, each and every one who is in charge of this in their care or his own cath lab and their procedures.
Dr Maria Andreassi: I agree. We all of our findings can contribute to the increase of cross cultural assessment in cath lab and by promoting the diffusion but not the reduction technologies whereas diligent about your protection habits. Moreover it is important to let the design, the relationship between occupational radiation exposure, clinical risk and there are very important future studies studying larger population. We should focus on the molecular epidemiology studies by using biomarkers and this will be clinical and points as early predictors of a clinical event. Because this information is a model likely to better define the risk of radiation use disease at low doses as a comparative tool, the classical epidemiological approach that require a very large sample sizes spread over [inaudible 00:20:51].
Now it's time where largest studies involving scientific societies at an international level. Possible breaking the additional exposure in already recruited the Roth case. And by combining the conventional epidemiology, and the molecular studies and the expected results to better define the clinical risk as a good lesson to implement a more effective protection program. And better as the surveillance at the individual level.
Dr Carolyn Lam: That is wonderful. And thank you, this truly is an international call, isn't it? Another thing that we should keep in mind that all measures that we use to protect our patient from receiving excessive radiation is likely to help us as well as cardiologists.
Thank you so much, both of you, for joining me today on this podcast. What an important message and I'm sure that our listeners will agree. Thank you listeners for joining us. 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 Centre and Duke-National University of Singapore. Our feature discussion today centers on patients with acute stroke due to large vessel occlusion, and asks the question, "Does interhospital transfer prior to thrombectomy relate to delayed treatment and worse outcomes?" Well, stay tuned for more right after these summaries.
Our first original paper this week tells us that cardio protection is alive, and mitochondrial cardiomyocyte calcium-activated potassium channels of the BK type may be a promising target. In this study from first author Dr. Frankenreiter, corresponding author Dr. Lukowski, from University of Tuebingen in Germany, the authors used a combination of transgenic, pharmacologic and electrophysiological approaches to show that mice with a cardiomyocyte-specific knockout of BK channels had larger infarct size after 30 minutes of coronary occlusion, and 120 minutes of reperfusion, and were less protected by ischemic pre- and post-conditioning maneuvers, such as guanylate cyclase stimulators or activators and phosphodiesterase-5 inhibitors.
In a chronic infarct model, mice with cardiomyocyte-specific knockout of BK channels had more fibrosis and lower left ventricular function. Mechanistically, the activation of BK channels in the inner mitochondrial membrane by cyclic GMP and protein kinase G was identified by patch clamping, and resulted in reduced formation of reactive oxygen species and activation of cardioprotective signaling. In summary, deficiency of BK channels in cardiomyocyte mitochondria rendered the heart highly vulnerable to ischemic and reperfusion injury, whereas the beneficial effects of cardioprotective agents known to target the nitric oxide cyclic GMP pathway required these cardiomyocyte BK channels. This thus establishes these cardiomyocyte mitochondrial BK channels as a promising target for limiting acute cardiac damage and adverse long-term events following myocardial infarction.
The next study suggests that integration of maximal myocardial blood flow and coronary flow reserve, termed coronary flow capacity, may be helpful in predicting cardiovascular mortality in patients with stable coronary artery disease. First author Dr. Gupta, corresponding author Dr. Di Carli, and colleagues from Brigham and Women's Hospital, quantify myocardial blood flow and coronary flow reserve in more than 4,000 consecutive patients referred for myocardial perfusion PET scans from 2006 to 2013.
Maximal myocardial blood flow of less than 1.8 mLs per gram per minute, and coronary flow reserve of less than two, were considered impaired. Four patient groups were then identified based on the concordant or discordant impairment of maximal myocardial blood flow, or its coronary flow reserve. The authors found that in patients with known or suspected coronary artery disease, impaired coronary flow reserve with preserved maximal myocardial blood flow identifies patients at an increased risk of cardiovascular mortality, despite a lack of myocardial ischemia. Patients who may be targeted for initiation or intensification of lifestyle preventive therapies for cardiovascular risk reduction. Conversely, preserved coronary flow reserve, even in the absence of impaired myocardial blood flow, identifies patients at low risk, in whom the need for revascularization should be reevaluated.
The next study provides insights into cardiac regeneration, particularly with regards to using resident cardiac progenitor cells expressing the tyrosine kinase receptor c-Kit, which is being tested in clinical trials. In this study from first authors Dr. Chen and Zhu, corresponding authors Dr. van Berlo from University of Minnesota and colleagues, the authors used single-cell sequencing and genetic lineage tracing to show that there was innate heterogeneity within these c-Kit positive cardiac cells, where some have either endothelial or mesenchymal identity. Cardiac pressure overload resulted in a modest increase in c-Kit derived cardiomyocytes, with significant increases in the number of endothelial cells and fibroblasts. On the other hand, doxorubicin-induced acute cardio toxicity did not increase c-Kit derived endothelial cell fates, but instead induced cardiomyocyte differentiation.
Although the overall rate of cardiomyocyte formation from c-Kit positive cells was below clinically-relevant levels, the authors further showed an important role for p53 in the differentiation of c-Kit positive cells to cardiomyocytes. Thus, this paper shows that different pathologic stimuli induced different cell fates in c-Kit positive target cells. These are novel findings that could aid in the development of strategies to preferentially regenerate cardiomyocytes.
Since December 2014, a series of pivotal trials have shown that endovascular thrombectomy was highly effective in acute stroke management, prompting calls for reorganization of stroke systems of care. But how have these trials influenced the frequency of endovascular thrombectomy in clinical practice? Well, the last original paper in this week's journal tells us how. First and corresponding author, Dr. Smith from University of Calgary in Alberta, Canada, and colleagues, used data from the Get With The Guidelines stroke program to determine how the frequency of endovascular thrombectomy has changed in U.S. practice. They analyzed prospectively-collected data from a cohort of more than two million ischemic stroke patients, admitted to more than 2,000 participating hospitals between 2003 and the third quarter of 2016.
The authors found that the use of endovascular thrombectomy for acute ischemic stroke accelerated sharply after the publication of pivotal randomized control trials beginning in December 2014. The endovascular thrombectomy case volume doubled at hospitals providing therapy. In the third quarter of 2016, endovascular thrombectomy was provided to 3.3% of all ischemic stroke patients. This represented 15.1% of all patients who were potentially eligible for endovascular thrombectomy based on stroke duration and severity. In summary, endovascular thrombectomy use is increasing rapidly, however there are still opportunities to treat more patients. Reorganizing stroke systems to route patients to adequately resourced endovascular thrombectomy-capable hospitals might increase treatment of eligible patients, improve outcomes, and reduce disparities.
Coming right up, we will be discussing even more about endovascular thrombectomy in acute stroke management. Just hang on, our feature discussion is coming right up.
Endovascular treatment with mechanical thrombectomy is beneficial for acute stroke patients suffering a large vessel occlusion. And that is in the guidelines, however we also know that treatment efficacy is highly time-dependent. And so, will interhospital transfer to an endovascular-capable center help in cases of acute large vessel stroke? Well, today's feature paper really helps to present novel data to answer that question. And it is from the STRATIS study. I'm so delighted to have with us the first and corresponding author, Dr. Michael Froehler from Vanderbilt University Medical Center, who will tell us about his findings, as well as Dr. Graeme Hankey, associate editor from University of Western Australia, joining us today. Welcome, gentlemen.
Dr. Michael Froehler: Hello Carolyn.
Dr. Graeme Hankey: Thank you Carolyn.
Dr. Carolyn Lam: Thanks for making the time. Mike, tell us about the STRATIS study. What inspired it, what you found.
Dr. Michael Froehler: Well, the STRATIS study was actually a large registry of the use of the Solitaire device for large vessel occlusion. Those results, the primary results, were published separately. But what we did in this study is look at one key aspect of the system of care for stroke delivery, in terms of its effect on time to treatment and patient outcomes.
And so in short, what we found is that patients that are transferred from one hospital to another for mechanical thrombectomy take longer to receive treatment, and do worse in terms of functional outcome, compared to the patients that present directly to that thrombectomy center.
Dr. Carolyn Lam: Wow. Could you put some numbers to that?
Dr. Michael Froehler: Well, so we looked at 984 patients, almost a thousand patients. And what we found was that the time from stroke onset to revascularization, until the time the vessel was actually opened, was 202 minutes on average, for patients that presented directly to the thrombectomy center. Compared to over 311 minutes for patients that were transferred from one hospital to another. So that's a difference, on average, of over 100 minutes.
Dr. Carolyn Lam: And I really was impressed with this other analysis you did. So I was wondering if you could share, where you did a hypothetical bypass modeling. Could you tell us about that? Because I thought that was really practical with a feasible message as well.
Dr. Michael Froehler: I'm excited about that, and I should also share with you that we're working on a more in-depth bypass analysis, to really understand the implications of going to one center directly versus another. But the model that is built in to this publication is really designed to answer one or two questions. And the first is, how much time would we save if we went directly to the thrombectomy-capable center, compared to what actually happened? Meaning the patient was taken to a regional hospital and then subsequently transferred to the thrombectomy-capable center. And this was basically an ideal scenario.
So if they were taken to one hospital and then transferred to another, we simply calculated what the maximum driving time from the starting position to the thrombectomy-capable center would be. And that did rest on the assumption that you actually had to drive past the first hospital. We didn't take any shortcuts in terms of the driving, and probably that small amount of driving time is actually shorter than the number that we found in our calculation.
So the first question was, how much time would we save with that bypass? And the second question was, what kind of impact would that have on IV-tPA? Because, as a lot of us are thinking right now, with strong evidence in support of endovascular therapy for large vessel occlusion, if necessary how should we prioritize getting to endovascular treatment versus the standard therapy that we've known for 20 years, which is IV-tPA? And if you've got a choice, which one is more important?
I don't know the answer to that question, but to try and help lead up to it, we did this hypothetical bypass analysis to look at the impact of bypass, driving directly to the thrombectomy center, the impact of that on the time to delivery of IV-tPA. And so that was really the second question that we asked with this hypothetical bypass analysis.
Dr. Carolyn Lam: Yeah. I love that analysis, because I agree with you, it's a very, very practical question, and it's the way we clinicians think, right? So, tell us, what's the bottom line?
Dr. Michael Froehler: So, the bottom line is, you're gonna save about an hour and a half if you bypass the regional hospital and go directly to the thrombectomy-capable center. On average, you're gonna get to the ultimate treatment center 91 minutes sooner, compared to the transferred group. Contrast that 91-minute time savings with a delay of IV-tPA delivery of 12 minutes. So yes, tPA will be delivered a little bit later, but endovascular therapy will be delivered much sooner.
Now, that solution is probably not going to work everywhere, depending on your geography. So one of the other things we did within the hypothetical bypass analysis was limit that analysis only to patients who were transferred within a 20-mile radius. And that doesn't seem like a long distance, but actually there's a lot of patients in that group, that are still taken to the nearest hospital and then need to be transferred to another hospital that may be less than 20 miles away.
So if we looked at that group of patients, then thrombectomy is still performed an hour and a half earlier, in that analysis it was 94 minutes earlier, but IV-tPA was delayed by only seven minutes. So certainly, there is a large group of patients out there that are perhaps being taken to hospitals that are not necessary, it's not a necessary stop.
Dr. Carolyn Lam: Wow, Mike, this is really amazing results, it's starting to make me think of the old days of acute myocardial infarction treatment, when we were thinking of intravenous thrombolytics, comparison to primary PCI, an analogy and comparison that was also mentioned in the accompanying editorial that you invited. Graeme, would you like to share some of your thoughts on the implication of all this?
Dr. Graeme Hankey: Just to take a step back, of course this begins with a stroke occurring out in the field. And unlike acute coronary syndromes, where chest pain is the major symptom, there are many symptoms of stroke. And the first problem is trying to identify the patient who has actually had a stroke, and in particular, one of the 15% or so who's had a large vessel occlusion, who's amenable to large vessel mechanical thrombectomy. So in the field we have an issue with clinical triage, and trying to work out who's the one in six who really need endovascular therapy, and who are the five in six who perhaps don't.
And we're trying to develop clinical triage scales like the RACE scale to work out in the ambulance where someone should go. But we still haven't nailed that yet. Then you have scales that are very sensitive but not very specific, and have a high sort of false-positive rate. So then the question at the ambulance is, where does it go, to the hospital, the primary stroke center nearby, and give the patient the earliest opportunity to get tPA?
And that's the potential benefit of early transfer to a primary center, but tPA is not very effective in dissolving these big clots in large arteries. And so, of course the trials have shown a substantial benefit of endovascular therapy to remove the clots via thrombectomy. But those resources, they're only really limited to comprehensive stroke units, and that's what this paper was about. So the trade-off is early transfer to the primary center so you can get some tPA, versus delaying, as Michael has shown, by 1 1/2 to two hours on average, to get to a comprehensive center that can access the expertise of endovascular thrombectomy experts.
And this paper is really taking us forward in emphasizing again that time is brain, and we really don't want to delay. Perhaps there's a small trade-off in driving a little bit further, another 20 miles at the most perhaps, to get to a comprehensive center directly. And there may be some who are not shown to have a large vessel occlusion at that comprehensive stroke center, but the overall benefit is probably offset, the few who might miss out on tPA. And so this is a really important study, the largest registry of large vessel occlusion patients to observe and compare the outcomes after adjusting for all the different factors. And give us some clues, that perhaps we really need to be trying to focus on building our resources in comprehensive stroke centers, and also being able to more accurately identify those who are likely to benefit and go directly there.
Dr. Michael Froehler: I agree with everything Graeme said, and I would just amplify one thing that he said, that it does depend on distance, and those distances in turn depend on your own geography. We did an analysis of all our transferred patients and then limited it to those that were within a 20-mile radius. For Graeme in Western Australia, you know Graeme's mailbox is probably 20 miles away. And so there are huge distances in Western Australia to account for. And it may not be possible.
Dr. Carolyn Lam: Contrast that to me in Singapore. I think if I drive any bit more, and I'll be driving out of my country already.
Dr. Michael Froehler: I think that you make a great point though, Carolyn, that the solution that works for metro Singapore is not what's going to work for rural Western Australia. And we've seen this in New York City, for example. My colleagues at Mount Sinai are looking at different ways to deliver care across metro New York, which obviously is very different compared to myself in Nashville, Tennessee. So the right solution is not gonna be the same solution for everyone.
Dr. Graeme Hankey: And that's right Carolyn, because in rural places like out in Western Australia, we are learning now that another important message is to try and help upscale and reorganize our primary stroke centers, or just our medical centers out in the rural and remote areas. Because as Mike's paper shows, the delays once someone comes to a primary stroke center or a rural center, is about 30 minutes for diagnosis, about 30 minutes to arrange the transport, and about 30 minutes to actually do the transport.
So we need to once trying to develop comprehensive stroke units, also build up those peripheral hub and spoke centers to be more slick with their diagnosis, arrangement of transport, and transport times. And one of the important things I think is, we need our primary centers, when a stroke does come, to not just do a plain CT to exclude hemorrhage, but to do a CT angiogram at the time. And find out those who really do have an occlusion, rather than putting them all on the plane and sending them down, and quite a few of them don't actually have an occlusion by the time that they've got here. They haven't been fully investigated, it's just an extra five minutes to do the contrast CT angiogram at the time in the primary center if they're gonna go there.
Dr. Michael Froehler: I think the one other thing I should add, and this is just to reflect back on something Graeme said a minute ago, is that one of the differences we found that really came out of that bypass analysis is the impact on tPA was smaller than we expected. Because the door-to-needle times are actually much longer at the regional hospitals that are not thrombectomy-capable, compared to the thrombectomy centers themselves, that are not only obviously delivering mechanical thrombectomy, but are actually delivering IV-tPA much sooner in terms of door-to-needle times.
Dr. Carolyn Lam: So, room for improvement even for non-endovascular-capable centers, isn't it?
Dr. Michael Froehler: Right, I think it's another area where there's room for improvement.
Dr. Carolyn Lam: Please 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. This week's journal features important information, that will aide identification of children with latent rheumatic heart disease, who are at highest risk of unfavorable outcomes. This important discussion is coming right up after these summaries.
The first original paper this week describes the largest study to date to examine payer approvals and rejections of PCSK9 inhibitor therapy, and describe the patient characteristics associated with successful prescribing. First author, Dr. Hess, corresponding author Dr. Yeh and colleagues from Beth Israel Deaconess Medical Center in Boston, Massachusetts, performed a retrospective descriptive cohort study utilizing nationwide pharmacy claims linked to electronic medical records from a nationwide data warehouse. The data set included over 220 million patients from all 50 states, and all pair types with more than 5,000 distinct health plans. PCSK9 inhibitor prescriptions were submitted for 51,422 patients in the pharmacy data set.
The authors found that among patients who were prescribed a PCSK9 inhibitor, 47% were approved for coverage by the payer. Variables that were associated with approval included age above 65 years, history of atherosclerotic cardiovascular disease, prescription by a cardiologist or a non-primary care provider, statin intolerance, longer statin duration, and non-commercial payers. Interestingly, higher LDL cholesterol levels were not associated with higher approval rates. Commercial third-party payers had the lowest approval rates of 24 from 4% and Medicare had the highest at 60.9%. Thus, rates of approval for PCSK9 inhibitor therapy are low, even for patients who appear to meet labeled indications. While a combination of clinical characteristics increase the likelihood of approval, payer type is the most significant factor.
The next study identifies a novel mitochondrial localized protein that plays a role in cardiac dysfunction, remodeling, and heart failure. This protein is FUN14 domain-containing 1, or FUNDC1, a highly conserved outer mitochondrial membrane protein. In today's study, first author, Dr. Wu, co-corresponding authors, Dr. Xie and Zou from Georgia State University, and their colleagues, showed that in cardio myocytes, FUNDC1 bound to inositol 1, 4, 5-triphosphate type 2 receptor, to form mitochondria-associated endoplastic reticular membranes.
These, in turn, modulate a calcium release from endoplasmic reticulum into mitochondria and the cytosol. FUNDC1 deletion lowered the levels of calcium in both mitochondria and the cytosol. A reduction at intracellular calcium resulted in mitochondrial fusion, mitochondrial dysfunction, cardiac dysfunction, and heart failure. In summary, this study identifies FUNDC1 as a novel mitochondrial localized protein that plays a role in maintaining mitochondrial dynamics, and cardiac function, and may therefore be a therapeutic target in heart failure.
The next study takes a deep dive into the J-Curve phenomenon of systolic blood pressure by providing an experimental approach to an observational paradigm. First and corresponding author, Dr. Kalkman, from University of Amsterdam and colleagues assess the association between on-treatment systolic blood pressure levels, cardiovascular events, and all cause mortality in patients randomized to different systolic blood pressure targets in the pool database of the SPRINT-6 and ACCORD trials. For both the intensive blood pressure target of less than 120 millimeters mercury, and the conventional target of less than 140 millimeters of mercury, the authors found an identical shape of the J-curve was present with a [inaudible 00:04:44] for cardiovascular events and all cause mortality just below the systolic blood pressure target.
The advantage of the intensive treatment group persisted at any level of the difference between the intended target and the achieved blood pressure targets. As discussed in an accompanying editorial by Dr. Verdecchia from Hospital of Assisi in Italy, these data suggest that if two patients achieve identical low values of blood pressure during treatment, prognosis is expected to be better in the patient actually targeted to achieve low values. Conversely, the outcome might be worse in the patient randomized to a higher blood pressure target, because low values in this case possibly reflect masked or unmasked confounders linked to a poorer outcome.
Thus, physicians should not be reluctant in lowering blood pressure in their patients because of an expected detrimental effect of BP reduction on death or major cardiovascular events. Rather, they should carefully monitor the possible occurrence of other adverse effects linked to blood pressure lowering, such as syncope, renal impairment, or electrolyte disturbances. This study further suggests that the benefit or risk associated with intensive blood pressure lowering treatment can only be established via randomized clinical trials and should not be extrapolated from observational data.
The final study establishes a causal link between dysregulated Tryptophan metabolism and abdominal aortic aneurysm. In a series of elegant mouse experiments from first author, Dr. Wang, two corresponding authors, Dr. Liu] and Ding from Georgia State University in Atlanta, Georgia, the authors establish that 3-Hydroxyanthranilic acid or 3-HAA, a key Tryptophan catabolite of the Angiotensin II induced abdominal aortic aneurysm in vascular smooth muscle cells was indeed responsible for Angiotensin II induced abdominal aortic aneurysm in Vivo. 3-HAA activated nuclear factor kappa-B transcription factor, promoted matrix metallopeptidase 2 expression in vascular smooth muscle cells. Human abdominal aortic aneurysm samples had stronger staining with the antibody against 3-HAA, than those in the adjacent non-aneurysmal aortic sections of these samples.
The identification of 3-HAA in Angiotensin II triggered abdominal aortic aneurysm and in human patients with abdominal aortic aneurysms, suggests that Tryptophan derived metabolites may be a biomarker for abdominal aortic aneurysm diagnosis. Furthermore, agents that alter Tryptophan metabolism may have a therapeutic potential in preventing or treating abdominal aortic aneurysms. Well on that intriguing note, we're at the end of this week's summaries. Now, for our featured discussion.
Today's feature paper really reminds us that rheumatic heart disease remains the most common cardiovascular disease among the world's youth. These days, echocardiographic screening provides a promising tool for early detection. However, the utility of this tool really depends on knowing the natural history of screen detected rheumatic heart disease, so-called latent rheumatic heart disease. Now, that has remained clear until today's paper. I'm so pleased to have with us the first and corresponding author, Dr. Andrea Beaton, from Children's National Medical Center in Washington D.C., as well as Dr. Bongani Mayosi, Associate Editor from University of Cape Town, South Africa. Andrea, could you start by letting us know about your study and what you found?
Dr. Andrea Beaton: As you mentioned, over the last decade or so it's become clear that in addition to the substantial burden of clinical rheumatic heart disease that we see around the world in low and middle income countries, there's also an even larger burden of latent rheumatic heart disease or early rheumatic heart disease that we can see on echo. This brings up the question if echo screening might represent a very powerful tool for rheumatic heart disease control, but we can't move forward with that discussion until we understand the rate of progression of children who are found to have echo detected rheumatic heart disease, and if we can do something to intervene to prevent progression in that population.
That something is likely penicillin, which is known to prevent progression in clinical rheumatic heart disease. To start to address that question, we followed a large cohort of children who had been diagnosed with echo detected rheumatic heart disease through school-based screening in different areas of Uganda and had collected about 227 cases of children with latent rheumatic heart disease who had been in clinical followup between two and a half and almost six years.
Dr. Carolyn Lam: Great. Could you tell us what you found about the progression and risk factors perhaps of progression, which I think are most significant?
Dr. Andrea Beaton: Right, so this is the largest natural history cohort of children with latent rheumatic heart disease to date and four major findings emerged from our study. The first is that we find a lot of echo detected rheumatic heart disease in low income settings that is more advanced. What we found is that children, even if this is their first time of diagnosis at echo screening, if they had moderate to severe rheumatic heart disease on screening, if they had poor outcomes even if over a very short time period. In our study, children with moderate to severe disease, only 10% of those children improved over the study period and 10% had died after only two to five years of followup.
We also saw that kids with mild, but definite rheumatic heart disease, which is more criteria for rheumatic heart disease than borderline, showed worse outcomes. Although, both children with mild definite and borderline disease had substantial risk of progression. 25% progressed in the mild definite group and 10% in the borderline rheumatic heart disease group. That tells us that even with very minor changes on echo screening, there is substantial risk of progression to more severe rheumatic heart disease, because we had a larger cohort using a multi-variant model.
We also found that there were features of rheumatic heart disease that put children at higher risk of progression. In our cohort, if children had aortic insufficiency at the time of screening, or some specific morphological changes, or changes in the mitral valve at time of screening, then they had higher risk of progression. While older age at time of screening showed a protective effect against progression.
Dr. Carolyn Lam: Wow. Andrea, congratulations on this remarkable study and you've highlighted so many important public health messages just in this one study. Bongani, what do you think was the most important or significant finding?
Dr. Bongani Mayosi: The most important finding is the reflection of the progression even in the mild and borderline cases. I think there has been an understanding that the definite cases do have a higher rate of progression and on top of that, I think showing the fact that there are some predictors that can be detected on echo is also very useful. Those with more advanced disease categories, those with younger age, as well as those with morphological valve abnormalities, I think those are very, very valuable points. Of course, the other point that is not all here is the fact that the majority of the initial progression appears to occur early and this is brought out in this study because of the serial echos that were done, which is again, another very valuable and a unique aspect of the study.
Previous studies have only done an echo at the time of diagnosis and perhaps an echo at the end of the followup period. I think that these features really make this study a valuable one. There is one question though that I wanted to put to Andrea, the issue of auscultation is one that we realized very early was not very useful for screening patients with latent rheumatic heart disease. We missed too many. I'd like to ask you now, once we've identified patients with latent disease, do you think auscultation of those patients could in fact identify the ones with clinical disease? Presumably, the more severe aortic regurgitation, mitral regurgitation, may be audible using a stethoscope? In other words, now shifting the role of the stethoscope not so much for diagnosis, but for risk stratification. I just want to know if you looked at this issue at all in this particular cohort?
Dr. Andrea Beaton: That's a really good question, Professor. We did not specifically look at the role of auscultation in this cohort. Although, it stands to reason that children with moderate to severe rheumatic heart disease, which by our definitions meant at least moderate to severe regurgitation at one of the valves, or presence of mitral stenosis would be audible. In that way, I think separating out children with moderate to severe disease, versus children with mild definite and borderline disease, would be quite possible and reasonable by auscultation.
My worry with the use of auscultation is I don't think it would separate out well children with mild definite disease, who by definition could have no more than mild regurgitation at any one valve, from children with borderline disease. Whether that distinction is important, I think still remains to be understood, but it would not be a very sensitive way to follow children until they had progressed to the point of having much more significant disease. I think echo still remains incredibly sensitive compared to auscultation for minor progressions, which to be clear, were included here as counting as progression of disease, even minor changes on echocardiographic evaluation.
Dr. Carolyn Lam: I have a question along the same lines Andrea, what kind of expertise was required for these echocardiographic screening procedures, both of the acquisition and then the interpretation? I do notice that you had a trained pediatric cardiologist with expertise in rheumatic heart disease who actually re-reported some of the echos. Do you think this is needed? What do you think about that?
Dr. Andrea Beaton: This is a complicated question, but a good one. A lot of the research that we've done outside of this paper has been looking at the ability to task shift echo screening, so to have non-physicians, not experts conducting echo screening. What we found across the board, as well as other groups around the world have found, is that you can train non-experts in a relatively short period of time to both screen and diagnose, at least on a screening basis, the presence of absence of rheumatic heart disease. For the purposes of this study, we're using very precise and very detailed diagnosis. According to the World Heart Federation criteria, which do really require experts to interpret.
Dr. Bongani Mayosi: The other issue, Andrea, which you highlight in the paper is the whole issue of the definition of progression, and regression, and the fact that there isn't consensus in the field about how we handle that, which results in papers not being comparable among each other. What do you suggest is the way of taking this forward so that we can build a consensus and a way of actually following up this patients that will be comparable between studies?
Dr. Andrea Beaton: That's a really important question and something we struggled with while we were writing this paper. You'll note in our paper that we reported it in two different ways because we couldn't come to a consensus and we thought both had some legitimate importance. Most of the papers in this field have reported the groups as progression and as stable lumped together, versus regression or improvement of disease. We felt the most important endpoint and something we had the numbers to power, was progression by itself. How many children were getting worse over the study period? In one sense, we powered it progression, versus stable plus regression, trying to dichotomize it still.
Then on the other hand, we thought that it was important if you had mild definite disease, even if you remained stable and mildly definite, and so we reported differently on the second outcomes based on if you had definite disease where we grouped progression and stable together, versus if you had borderline where we only counted true progression as a change for the worse. I don't have the perfect answer of how this should be reported. Although, I think the more granular we can be as we report these studies going forward, the more we can separate out the data that is reported to make it comparable. A lot of the previous papers, I think, lack the granularity needed to compare in different ways.
Dr. Carolyn Lam: We're coming to the end of our time, so may I just wrap up by asking Andrea, what do you think are the next steps?
Dr. Andrea Beaton: That's a good question and something I feel strongly about. Another part of our paper showed that the other incredibly important outstanding question is if we can find these kids, can we change what happens to them over time, and does penicillin do that? Even with our large cohort of patients, we couldn't determine the effect of penicillin on progression or trajectory of these children over this time period. It's something that now that we have large numbers of children and still can't come to a conclusive response, I think warrants a randomized control trial to look at the effect of penicillin on children with echo detected rheumatic heart disease, because that's really what's going to drive the policy on if echo screening makes sense as a public health policy to reduce the global rheumatic heart disease burden.
Dr. Carolyn Lam: I'm sure listeners out there, you've appreciated this as much as I have. 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 novel data informing the choice between conscious sedation and general anesthesia for transcatheter aortic valve replacement. A very relevant discussion for those of us who see these patients. Stay tuned, that's coming right up after these summaries.
Subclinical hyperthyroidism is known to be associated with an increased risk of atrial fibrillation, but the association with thyroid function in the normal range or subclinical hypothyroidism is unclear. That is, until today's study, which shows us that variation in thyroid function within the normal range is associated with atrial fibrillation.
First author, Dr. Baumgartner, corresponding author, Dr. Rodondi and colleagues from University of Bern in Switzerland, conducted a systematic review and obtained individual participant data in more than 30,000 participants from 11 prospective cohort studies that measured thyroid function at baseline and assessed incident atrial fibrillation, which occurred in 8.6% of individuals.
They found that in youth thyroid individuals, there was a significant increase in the risk of atrial fibrillation with increasing free T4 levels within the reference range. Risks did not differ significantly by age and sex.
Conversely, there was no association between TSH levels within the reference range, or subclinical hypothyroidism and the risk of atrial fibrillation. Thus, free thyroxin levels might add to further assessment of atrial fibrillation risks. Further studies are needed to investigate whether these findings apply to thyroxine treated patients.
The next study provides insight into how exercise promotes metabolic remodeling in the heart. First author, Dr. Gibb, corresponding author, Dr. Hill and colleagues from University of Louisville, use radiometric, immunologic, metabolomic and biochemical assays to measure changes in myocardial glucose metabolism in mice subjected to acute and chronic treadmill exercise.
They found that in the heart, glucose utilization via glycolysis was reduced during exercise and in the early recovery period after exercise. Low rates of myocardial glycolysis were sufficient to activate gene programs that instigate physiologic cardiac growth. Metabolic inflexibility of the heart, such as occurs in heart failure and diabetes, was sufficient to diminish mitochondrial function.
Phosphofructokinase mediated changes in metabolism appeared to regulate genes involved in processes critical for metabolic remodeling, transcription, cell division, differentiation, cell proliferation and contraction. Thus, this study provides important preclinical evidence, showing how exercise-induced changes in glucose metabolism may promote physiologic cardiac growth.
The next study addresses the question of whether antiarrhythmic drugs are safe and effective when non-shockable rhythms evolved to shockable rhythms during resuscitation for out of hospital cardiac arrests. In this study from first and corresponding author, Dr. Kudenchuk of University of Washington and his colleagues, patients who initially presented with non-shockable out of hospital cardiac arrests were randomized upon subsequently developing shock refractory VF or VT to receive amiodarone, lidocaine or placebo by paramedics.
The primary outcome was survival to hospital discharge, with secondary outcomes, including discharge functional status and adverse drug-related effects. The authors found that outcome from non-shockable turned shockable out of hospital cardiac arrest was poor, but not invariably fatal. Though not statistically significant, point estimates for survival showed a trend to greater survival after amiodarone or lidocaine than placebo without increased risk of adverse effects or disability. Together, these findings may signal a clinical benefit that invites further investigation.
The final study provides experimental data supporting the importance of a novel Cardiokine governing the local environment in infarcted hearts and determining the fate of implanted cells. This novel Cardiokine is C1q/tumor necrosis factor-related protein-9, or CTRP9, which is a novel pro survival Cardiokine that is significantly down regulated after myocardial infarction.
In today's study by co-first authors, Drs. Yan and Guo and co-corresponding authors Drs. Ma and Wang from Thomas Jefferson University in Philadelphia, mice were subjected to myocardial infarction and treated with adipose-derived mesenchymal stem cells, CTRP9 or their combination. The authors found that administration of adipose-derived mesenchymal stem cells alone failed to exert significant cardio protection.
However, administration of these cells in addition to CTRP9 further enhanced the cardioprotective effect of CTRP9, suggesting a synergistic effect. CTRP9 promoted adipose-derived mesenchymal stem cell proliferation, survival, migration and attenuated cardio myocyte cell death by signaling mechanisms that included binding with N-cadherin, activation of ERK, MMP9, and ERK-Nrf2 signaling and upregulation or secretion of antioxidative proteins.
In summary, these results suggest that CTRP9 is a Cardiokine critical in maintaining a healthy microenvironment facilitating stem cell engraftment in infarcted myocardial tissue. Well, that wraps it up for your summaries, now for our feature discussion.
Conscious sedation is very frequently used during transcatheter aortic valve replacement, or TAVR, but with limited evidence as to the safety and efficacy of this practice. Well, that is until this week's journal and this feature paper. We're so lucky to have with us the corresponding author, Dr. Jay Giri from Hospital of University of Pennsylvania, to discuss his novel findings, as well as Dr. Dharam Kumbhani, Associate Editor from UT Southwestern.
Jay, tell us your study findings and how this really helps us to characterize anesthesia choice and clinical outcomes of at least U.S. patients undergoing TAVR.
Dr. Jay Giri : We looked at 11,000 patients treated over a 15-month period in 2014 and 2015 with percutaneous transfemoral TAVR. Notably, this was a time period that was identified as the start of the era of conscious sedation for TAVR in the United States.
Also, this five quarter period that we looked at represented a time of relative technological stability where only two valve types, the Sapien XT and original Medtronic CoreValve were being used in America.
Looking at that 15-month period when conscious sedation was first being used in TAVR, we elected to compare those patients to a propensity matched group of patients who underwent TAVR by, what at that time was, the more traditional approach of general anesthesia.
Our primary outcome within hospital mortality, because we had complete followup for this outcome. We also looked at 30-day outcomes for which we had about 90% followup. What we discovered was actually an associated reduction in mortality, an absolute reduction of about 1% in the patients who were treated with conscious sedation.
We also noted that they had modest decreases in the hospital length of stay, as well as significant decreases in the rates of ICU length of stay and the rates of pressor or inotrope use during the procedure. Obviously, the most provocative of the findings was the fact that we seemed to discover, after propensity matching a slight improvement in in-hospital mortality that held true at 30 days, as well.
Dr. Carolyn Lam: Thank you, Jay. What important findings ... I mean, mainly because, we really didn't have much data, did we? About conscious sedation and TAVR before this. Now, it's observational data, and I suppose the question always becomes what about bias by indication? More well patients get selected for conscious sedation versus general anesthesia, perhaps? Or even the other way around. Could you elaborate a little bit on how you think that may have impacted results and the measures you took to look at that?
Dr. Jay Giri : I think it was something that we were highly aware of and I also have to give credit to Dr. Kumbhani and the editorial staff at circulation for pushing us on that issue of selection bias for the two procedures. The obvious concern here, when you saw that there was a potential mortality reduction with conscious sedation patients, was that perhaps the conscious sedation patients actually represented a healthier cohort to start with, or they were perhaps treated at centers that were more highly experienced and by operators that were more highly experienced with TAVR in general.
We tried to account for this in a number of different fashions. The first, as we mentioned, was with an inverse probability treatment weighted analysis that accounted for 51 co-variants that were balanced between the groups. Additionally, we did adjust for site characteristics and utilized a hierarchical method technique to take into account both the experience of sites and operators.
Finally and most importantly, we performed what's called a falsification end point analysis in a postdoc fashion to verify that it looked like other outcomes outside of things, like mortality, length of stay, things we would expect to be influenced by sedation type, ended up being equal between the two groups. Falsification end point analysis represents, essentially, a negative control. You're supposed to theorize for potential outcomes that you would think would not be influenced by your intervention. In this case, those outcomes we theorized were vascular complications, major bleeding and pacemaker implantation, which we theorized would not be influenced by sedation type. In fact, we discovered that those outcomes were similar after adjustment, even though they had some differences before adjustment.
Dr. Dharam Kumbhani: Jay, I want to congratulate you and your team on this paper. You guys really picked a very important topic to look at and then you jump ... as you outlined, you jumped through a lot of statistical hoops and try to really provide evidence for a field in which a randomized controlled trial is probably going to be just logistically probably hard to conduct, just given the sample size requirements, which also you've provided in your discussion.
I think all the metrics that you looked at as far as utilization of therapies and length of stay, things like that, I think many people believe that and you were the first one to systematically evaluate and show that.
As you alluded to, I think that mortality, and Carolyn mentioned that, as well. I think the mortality findings are very interesting. Again, it's always hard when you have observational data to really put a lot of stock into that and you guys, as you outline, looked at so many different ways of doing that.
Again, I guess, observational data are always inherently going to have that limitation, no matter what statistical rigor we put them through. They were definitely very thought-provoking and, as you outlined, it's definitely come at the right time as the field is exploding and more and more centers are getting facile at it.
The other thing that you mentioned, but which I want to make sure that people fully understand is that you also provided a very elegant analysis looking at site volumes, because traditionally the sites that are doing conscious sedation have done a number of TAVR's before and there is a very clear cumulative volume outcomes association, for TAVR.
By accounting for the totality of experience, so you adjusted for the cumulative volume that sites have been doing this, so these are not just the high volume, high throughput centers, which have a lot of experience doing 150, 200 TAVR's a year, that thereby have really good outcomes by virtue of being expert, both as operators and as sites, but rather potentially something that is related to conscious sedation aspect itself. You guys really stepped up and provided a very elegant analysis to try to dissociate the two issues here.
Dr. Carolyn Lam: Dharam, and you just provided a very elegant explanation of the thought processes that were going on with our editors about this paper. I join you in congratulating Jay. Just a question. This is the best available evidence now, what are we going to do about it? I mean, Dharam, you're an inventionist, what now?
Dr. Dharam Kumbhani: The issues were not so much related to efficacy, initially. The initial concerns were related to safety, and Jay's paper clearly addresses that. Then, in addition to that, it says, "Well, it's not just that it's a safe procedure, but it's also effective with potential patient level and hospital level benefits from having a robust conscious sedation program."
I guess the one question that I have about conscious sedation and, Jay, I would love to hear your thoughts on this, as well, is it is possible but it is usually not done, TEE's or transesophageal echos are typically not done when you're doing conscious sedation. It is possible, as I said. As you move towards lower risk patients, on the one hand, these would be ideal patients for conscious sedation because then it's almost like a day procedure, in some ways for them.
But on the other hand, the fidelity of being able to look for even small paravalvular leaks, things like that, may be harder with a transthoracic echo. I don't know, as we expand towards the oldest populations, whether we'll see a greater adoption of conscious sedation, or whether there'll be some scaling back.
Dr. Jay Giri : Two points on that. The first is, I totally agree that it's relatively unusual for a transesophageal echo to be performed in the setting of conscious sedation. There's no question, secondly that transesophageal echo allows for the most rigorous evaluation of paravalvular leaks.
It is striking, though, that the rates of paravalvular leaks, due to technological improvements to the valves, are significantly improving. Even since the time of our study two years ago, a new generation of valves is consistently coming out with leak rates in pretty well-conducted analyses that are in the low, single digit percentages for moderate leak or more.
Part of I think the move towards conscious sedation, even initially and especially as we go forward, is predicated on the fact of continuing technological improvements that essentially almost solve the leak problem.
I think it's true that there's always going to be a very small minority of patients that are stuck with concerns about paravalvular leak at the end of their TAVR procedure. For those who have moderate or greater leak, I think that the threshold for escalating care, even to intubation and TEE to evaluate that leak, I think should be relatively low in a lower risk population.
However, I think the point that you bring up about the potential harm of trace or trivial leaks, or mild leaks, which may not be perfectly interpreted with transthoracic echo and aortograms and [inaudible 00:16:41] assessments at the time of the valve placement. It's something we're going to have to keep a close eye on.
From a practical standpoint, I believe this train has left the station. Totally unscientific, but around the time they released the paper online. I just shot out a poll on Twitter and got about a couple of hundred responses from folks, what they're doing now.
Now, Twitter certainly, probably doesn't represent the average transcatheter valve operator in the world, but I was surprised to see that over 70% of the respondents favored a conscious sedation approach at this point in time, which obviously is much higher than what we saw in our paper from two years ago.
Dr. Carolyn Lam: Well, audience, I'm sure you enjoyed that. Thank you for joining us today. 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. This week's journal features novel results from the NCDR IMPACT Registry that informs us on risk prediction in patients with congenital heart disease undergoing cardiac catheterization. We'll be taking a deep dive into this right after these summaries.
The first original paper provides pre-clinical data showing that delayed repolarization may underlie ventricular arrhythmias in heart failure with preserved ejection fraction or HFpEF. First author Dr. Cho, co-corresponding authors Dr. Marban, and Cingolani from Cedars-Sinai Heart Institute and their colleagues, induced HFpEF in Dahl salt-sensitive rats by feeding them a high-salt diet from seven weeks of age. They showed that susceptibility to ventricular arrhythmias was markedly increased in rats with HFpEF.
Underlying abnormalities included QTc prolongation, delayed repolarization from down-regulation of potassium currents, and multiple re-entry circuits during ventricular arrhythmias. These findings are consistent with the hypothesis that potassium current down-regulation may lead to abnormal repolarization in HFpEF, which in turn predisposes to ventricular arrhythmias and sudden cardiac death.
The next paper shows that genetic testing can help to identify patients with pulmonary veno-occlusive disease who were misclassified as pulmonary arterial hypertension. Now, heterozygous mutations in the gene encoding the bone morphogenetic protein receptor type II or BMPR2 are the commonest genetic cause of pulmonary arterial hypertension. Whereas biallelic mutations in the eukaryotic translation initiation factor 2 alpha kinase 4 gene or EIF2AK4 gene are described in pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis.
In the current study, first author Dr. Hadinnapola, corresponding author Dr. Morrell, and colleagues from University of Cambridge performed whole genome sequencing on the DNA from 864 patients with pulmonary arterial hypertension, as well as 16 patients with pulmonary veno-occlusive disease all recruited to the NIHR BioResource – Rare Diseases study. They found that 1% of patients with a clinical diagnosis of pulmonary arterial hypertension actually carry the biallelic EIF2AK4 mutations. Patients who are diagnosed clinically with pulmonary arterial hypertension, but who had a transfer coefficient for carbon monoxide of less than 50% predicted and an age of diagnosis of less than 50 years were much more likely to carry these biallelic EIF2AK4 mutation. In fact, the diagnostic yield for genetic testing in this group was 53%.
Radiological assessment alone was unable to distinguish reliably between these patients and those with idiopathic pulmonary arterial hypertension. Importantly, these patients with biallelic EIF2AK4 mutations had a worst prognosis compared to other patients with pulmonary arterial hypertension. Thus in summary, younger patients diagnosed with idiopathic pulmonary arterial hypertension but with a low transfer coefficient for carbon monoxide, have a high frequency of biallelic EIF2AK4 mutations and should be reclassified as pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis. They have a poor prognosis and genetic testing can therefore identify these misclassified patients allowing appropriate management and early referral for lung transplantation.
The next study identifies a novel molecular target for the treatment of pathological cardiac hypertrophy. This target is SIRT2 [inaudible 00:04:33] poorly characterized member of the Sirtuin family of proteins, which is a family of class III NAD-dependent deacetylases that regulate metabolism and age-related diseases including diabetes and cardiovascular diseases. In the current study, first authors Dr. Tang and Chen, corresponding authors Dr. Chen and Liu from the Chinese Academy of Medical Sciences in Peking Union Medical College used wild-type and Sirt2 knockout mice, and showed that SIRT2 protein levels and activity were reduced during pathological cardiac hypertrophy.
SIRT2 deficiency promoted aging and angiotensin II induced pathological cardiac hypertrophy, and blunted metformin-mediated cardioprotective effects. On the other hand, SIRT2 overexpression repressed pathological cardiac hypertrophy. The molecular pathway involved deacetylation of liver kinase B1 at lysine 48 by SIRT2 to activate AMP-activated protein kinase sickling, which prevented hypertrophy of cardiomyocytes. Thus, SIRT2 is a potential target for therapeutic interventions in aging and stress-induced cardiac hypertrophy.
The next study is the largest comparison of the prognostic value of coronary artery calcium with functional stress testing in patients with stable chest pain. In this study from first and corresponding author Dr. Budoff from Los Angeles Biomedical Research Institute and colleagues, authors looked at the PROMISE trial where patients with stable chest pain or dyspnea, and intermediate pre-test probability for obstructive coronary artery disease were randomized to functional testing or anatomic testing.
Their main finding was that these chest pain populations referred for testing had a low event rate and both tests had different strengths. Coronary artery calcium had a high sensitivity for future cardiovascular events whereas functional testing had a high specificity. The clinical implications are that a normal coronary artery calcium score has a very low event rate and perhaps maybe used to avoid further cardiac testing in a stable chest pain population. On the other hand, an abnormal functional test result including information on exercise and symptoms has a moderate prognostic value.
Of note, coronary CT angiography provided better prognostic and discriminatory power than either coronary artery calcium or functional testing. The implications of these important results are discussed in an accompanying editorial by Dr. David Newby from Edinburgh entitled, Can I Have My Cake and Eat It? On that intriguing note, we've come to the end of today's summaries, now for our feature discussion.
For today's feature discussion, we are talking about an increasingly important population that is pediatric and adult patients with congenital heart disease undergoing cardiac catheterization. A little bit out of my usual comfort zone, but then you see, I'm with two spectacular experts today, Dr. Gerard Martin from Children's National Health System in Washington DC, one of the authors of today's feature paper; and Dr. Gerald Greil, Associate Editor from UT Southwestern. Welcome gentlemen.
Dr. Gerard Martin: Thank you Carolyn.
Dr. Gerald Greil: Thank you Carol.
Dr. Carolyn Lam: Gerard, no that would be Dr. Martin. Enlighten people like me who don't think about this every day, why the importance of looking at cardiac catheterization, and adverse outcomes in this particular population?
Dr. Gerard Martin: Carolyn, that's because of the tremendous advances in medicine, and particularly medicine that's dealing with children with congenital heart defects. Cardiac catheterization was once purely a diagnostic study. Now, it's a less invasive definitive treatment option for many of our pediatric and adult patients with congenital heart defects. As you may or may not know, congenital heart defects are the most common birth defects that impact nearly one out of every hundred live births.
As I mentioned, we have these tremendous advances. As a result of that, there are now over a million children living with congenital heart defects. In the USA alone, improvements in care over the past 50 years, there are now more adults than children living with congenital heart defects.
Dr. Carolyn Lam: Wow. Now, I understand. I mean, cardiac catheterization not just meeting diagnostic but therapeutic, and such an important patient population. Tell us about your study?
Dr. Gerard Martin: As we said, cardiac catheterization is now replacing surgery for some of our defects. For some of the more complex defects, catheterization is providing treatments that make the surgery easier. Now in surgery, we've had registries for many years. These registries provided measurement of survival that allow comparison of programs, and we didn't have that ability with cardiac catheterization. The American College of Cardiology developed the IMPACT Registry. That was to solely provide measurements of the outcomes of catheterization procedures in the children and adults with congenital heart disease.
Now, one aspect of the quality of the program is your rate of adverse outcomes; but simply measuring the number of adverse outcomes does not provide enough discrimination to compare programs. I think you can probably imagine that adverse outcomes will increase based upon the complexity of the type of patients you see, or the types of procedures that you might be performing. What we wanted to do was to create a risk standardization tool for our population where we can measure variation and performance between programs. If we can do that, then we can learn from the best performers to improve all the others.
Dr. Carolyn Lam: That's beautifully put. Could you tell us what you found?
Dr. Gerard Martin: Sure. The IMPACT Registry began on about 2011 and has grown from 50 sites to 111 sites in 2017. That's the majority of the sites in the United States that perform cardiac catheterization on children. We have now over 115,000 procedures. What we wanted to do with this is to look at some of the early procedures that were included and to see how adverse events were occurring. When we created the registry though, we used data variables from a previous research study in Boston called the CHARM.
They created a tool to risk standardized outcomes during procedures. They did it by coming up with four categories of procedures, and some four markers of hemodynamic vulnerability. We tested their methodology with IMPACT, and it didn't really performed particularly well. In this study, what we did was to increase the number of risk categories. We took the nearly 200 types of procedures we do in the cath lab and divided them into six categories. We also increased the indicators of hemodynamic vulnerability from four to six.
Now, what I mean by hemodynamic vulnerability? What is the patient's oxygen level when they go into the procedure? What is their blood pressure when they're in the procedure? Do they have one ventricle, or do they have two ventricles? What is the resistance in the lung vessels? All these are critically important. Lastly, we looked at some baseline patient characteristics. In other words, was age important? Sex, genetic conditions, or other comorbid conditions like the level of mechanical support that the patients were on. Then we put all that into our model to see if we could come up with a risk score.
Dr. Carolyn Lam: Right. The final adjustment model? Which factors that they include in the end?
Dr. Gerard Martin: We did find that there are lot of adverse events that do occur. We found major adverse events occurring in about same 7% of our patients. Most common adverse events were bleeding, or rhythm disturbances that require some medicine, or cardioversion during the procedure, or death during the hospitalizations. We did find that these major events were more common in the youngest patients or neonates, children under a month of age, or in patients with genetic disorders, or single ventricle physiology, and also patients that went to the cath lab with their kidneys not working very well.
In the end, we did create a risk adjustment model that included the type of procedure that was done, the number of hemodynamic vulnerability indicators, and whether or not the patient had renal insufficiency, or single ventricle physiology, or coagulation, and we found really good discrimination. Our discrimination had a C-stat of 0.76 in the derivation cohort, and 0.75 in the validation cohort. The slope of the curve was excellent, so we really think we have something now that we can use as a tool.
Dr. Carolyn Lam: Gerald, you're a pediatric cardiologist. Could you give us your perspective on how important these results are?
Dr. Gerald Greil: I think it's the largest and the first study, which kinds of give us a calibration in our field how successful interventions are. How we can make centers better without finger pointing on specific centers, and how to advance the field as a whole? From that perspective, I'm quite excited that the group offered us to publish this paper in circulation. I was kind of asking a question to Dr. Martin because obviously, all essentials are closely monitored. There's obviously data publicly available. Do you think there's a risk that this way to monitor centers within the United States or probably worldwide, that it's potentially preventing innovation or risky procedures?
Dr. Gerard Martin: I think that, that's a good question. I think it's one thing that whenever we talk about transparency or public reporting, it's an argument against it. I think that having a model like this, actually levels the playing field. In other words, centers that are risk averse who aren't particularly innovative, you'll be able to look at those centers, see what type of patients they're doing and look at their adverse events for a low-risk population. Then, you can also look and see some other centers that are doing more complicated procedures, higher risk, and you can see what their adverse event rate is.
Certainly, this is only talking about the adverse events. This has to be put together with the outcome of the procedure. In other words, if you're trying to relieve an obstruction, did you relieve it? Did you meet the intended goal of the procedure? This is only half of the story. The other part of it is, did you get the intended goal of the procedure? When you put the two of them together, perhaps some of those centers that are risk averse have lower complications, but maybe their success rate is lower. This will be able to tell the public everything they know, and they'll be able to tell their providers what they need to know to get better.
Dr. Carolyn Lam: I have to agree. Your paper does highlight, I think. Gerard, just one other question. What do you think our next steps?
Dr. Gerard Martin: The next step is to test the data. We have a new version of IMPACT that has rolled out, version 2 that has new procedures in it. Now, we have to test the data and we actually have to look for variability. Can we see a variation between the programs? Then, once we see if there's variation, if we see there is best performers and those performers that could improve, a question then is how do we take from what the best performers are doing to try and lift those that need to improve up. That's going to be the true hard work for this registry.
Dr. Carolyn Lam: Thank you so much for publishing it with us. Thank you so much audience for listening with us today. Don't forget to tune in again next week.
Dr. Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and back-stage 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 evidence we have for LDL-lowering therapy in primary prevention? For individuals with an LDL cholesterol above 190 mg/dL, well, you may think you know the answer, but today's featured discussion may surprise you like it did for me, and this is a must-listen in my opinion for those of us taking care of these patients. More soon right after these summaries.
How can we enhance the survival and therapeutic potential of human pluripotent stem cell-derived endothelial cells? Well, the first paper in today's journal tells us how. The first author Dr. Lee, corresponding doctor Dr. Yoon, from Emory University School of Medicine in Atlanta, Georgia, developed a novel, fully-defined, cell culture system to generate endothelial cells from human pluripotent stem cells. They not only showed that these endothelial cells had pro-angiogenic activities and exerted favorable therapeutic effects in repairing limb ischemia, but also showed that encapsulation of these cells in a biocompatible peptide amphiphile nanomatrix gel improved long-term survival of these endothelial cells in an ischemic environment and improved vessel-forming properties. This novel cell culture system and gel-mediated transplantation may serve as a novel platform for cell-based therapy.
The next study brings us one step closer to application of immunomodulatory therapies in pulmonary arterial hypertension. In the study, first author Dr. Saito, corresponding author Dr. Rabinovitch, and colleagues from Stanford University School of Medicine isolated lung immune complexes and pulmonary arterial hypertension target antigens from lung tissues from 16 patients with pulmonary arterial hypertension and 12 controls. SAM domain and HD1 domain-containing protein, which is an innate immune factor that suppresses HIV replication, was identified and confirmed as highly expressed in immune complexes from patients with pulmonary arterial hypertension. These immune complexes resulted from elevation in products of human endogenous retrovirus K. The human endogenous retrovirus K deoxyuridine triphosphate nucleotidohydrolase, or dUTPase, activated B cells, elevated cytokines and monocytes and pulmonary endothelial cells, and increased pulmonary arterial vulnerability to apoptosis, thus contributing to sustained inflammation, immune dysregulation, and progressive obliterative vascular remodeling. Furthermore, rats treated with the human endogenous retrovirus K dUTPase developed pulmonary hypertension. In summary, this study suggests that harnessing mechanisms that repress human endogenous retrovirus K expression and its sequelae could prevent and reverse pulmonary arterial hypertension.
The next study looked at the association of timing of coronary angiography with ischemic outcomes of non-STEMI who are at high risk with a Gray score of more than 140 in the TAO Trial. In this report from first author Dr. Deharo, corresponding author Dr. Steg, and colleagues from L'Hopital Bichat from Paris, France showed that in these high risk, non-STEMI patients, a very early invasive strategy of coronary angiography within the first 12 hours was associated with a lower risk of death in MI at 180 days compared to an early strategy of between 12 to 24 hours or a delayed strategy of between 24 and 72 hours. The bleeding risk was not different between patients managed with the very early, early, or delayed strategy. These observations deserve prospective confirmation in a randomized trial.
The next study provides contemporary mortality trends for STEMI and non-STEMI. In this paper from first author Dr. Puymirat, corresponding author Dr. Danchin, and colleagues from Hopital europeen Georges-Pompidou in Paris, France, the authors assess trends in the characteristics, treatments, and outcomes for EMI from five month-long registries conducted five years apart and spanning 1995 to 2015, including more than 14,000 patients admitted to cardiac intensive care units in metropolitan France. They observed major changes in the characteristics and management of both patients with STEMI and those with non-STEMI over the last 20 years. The mean age decreased in patients with STEMI and remained stable in patients with non-STEMI, whereas diabetes, obesity, and hypertension increased. At the acute stage, intended primary PCI increased from 12 to 76 percent in patients with STEMI. In patients with non-STEMI, PCI within 72 hours from admission increased from 9 to 60 percent. In parallel with these changes, six-month mortality consistently declined in patients with STEMI, whereas in patients with non-STEMI, six-month mortality reached a plateau after 2010. The authors concluded that future challenges will be to reduce pre-hospital mortality and to improve long-term survival after the acute myocardial infarction event.
That wraps it up for your summaries. Now for our feature discussion!
What evidence do we have from randomized trials supporting the benefit of LDL cholesterol lowering as primary prevention among patients with an LDL cholesterol above 190 mg/dL? You may be surprised to know that until today's journal, we had very little trial evidence supporting this. But I'm so pleased to have with us the corresponding author of our featured paper today, Dr. Kausik Ray from Imperial College, London, who's going tell us a bit more and discuss this very intriguing paper with our Editor for Digital Strategies, Dr. Amit Khera from UT Southwestern. Welcome, both.
Dr. Kausik Ray: Hi.
Dr. Amit Khera: Thanks for having us.
Dr. Carolyn Lam: Kaus, you are a familiar voice and so pleased to have you here. Please tell us, is this the first evidence we have from a randomized trial for primary prevention in those with LDL above 190? Tell us about it.
Dr. Kausik Ray: Yeah, it is. It really came about because we were interested in familial hypercholesterolemia and we used the level of 190 to talk about either primary hypercholesterolemia, which may have a genetic basis, or not. I kept hearing that there is no trial evidence, so you're not going to be able to ethically do a trial today despite the fact there's not much evidence, because most of us think that it's a bad thing to leave people on placebo in patients above 190, so I thought the only way to do this was to go historically to the WOSCOPS Study, which is, as you remember, 6,500 people, elevated LDL cholesterol. Interestingly, you go to WOSCOPS, the median LDL in that population is very close to 190. So, that gives a good starting point, thinking that we'll have at least half the population.
Now interestingly in WOSCOPS, although none of the patients had a history of myocardial infarction, a very small number of the 6,500, about 1,000 actually had evidence of some other vascular disease, so maybe a TIA, maybe angina, maybe some sort of ECG non-specific change of coronary disease. Today, you would say, well, actually, you've got to give these people a statin because there's evidence of vascular disease, PVD, et cetera. So we had to take those people out and that left us with 5,529. Once you break people down by LDLs above and below 190, you have 2,560. You could actually look at the randomized treatment effect of pravastatin, which was the statin chosen, over a five year period both above and below 190.
But interestingly, this was the first study and what we showed was that in this population, even with as little as 23% reduction in LDL cholesterol, over a five year period, you saw a statistically significant 27% reduction in CHD and if you take the usual 3 point MACE of current clinical trials, there was a 25% reduction, already statistically significant. We also had the ability to link data over 20 years. Remember, after the five year randomized treatment period, it becomes observational in nature, but what it showed was that when you gave nearly 40% in each arm statins and you followed people up this legacy effect, over a 20 year period, the people with the LDL above 190, that translated into this 28% reduction in CHD death. It translated into a 25% reduction in CV death, and actually an 18% reduction in all-cause mortality, which you didn't see in the population with slightly lower LDL cholesterol.
This is the best evidence we're ever going to get, really, and answer the question about what should we do in this patient population. Should we treat with lipid-lowering therapy? The answer, unequivocally, is yes, and the longer you treat, the more likely you are to see survival benefits.
Dr. Carolyn Lam: Oh, my goodness! I just love his paper. I have to humbly admit. I mean, it's in the guidelines already that we should treat these individuals with LDL above 190, and it really made me think how I'd taken for granted that there would be a whole body of evidence behind it from randomized trials, and you are right! This is the first, and likely going to be the last we're going to get, because we can't randomize them. So, congratulations. What you said just now, I can already hear myself playing this podcast to my patients. May I just ask, are there other remaining questions to answer, and then what do you also say to those that say, well what are the harms? How do you balance that with any potential harms?
Dr. Kausik Ray: In this particular study, given there was overall safety data observed in the WOSCOPS Trial population and in their extended follow-up in the overall 6,500 person cohort, we didn't go on and look at that. There was no evidence of harm in the extended follow-up of 6.500 people, so we didn't see the potential added gain in specifically looking for that. The main question we wanted to answer, because people had always pulled primary and secondary prevention patients together, and in fact, your best evidence is actually from CTT, pooling of primary and secondary prevention patients where they break the data down by an upper limit of about 175. With patients above 175, they don't specifically answer that question. So, to answer your question, we didn't look at that in the overall WOSCOPS Trial population. There was no signal for harm that was noticed. Even things like glucose elevation, if you remember in WOSCOPS, tended to be a little bit lower.
Dr. Amit Khera: Let me comment on a few things about this paper. First, I want to congratulate Dr. Ray and his colleagues. I was a history major and I think this is a great use of a historical tool. At this point, I think we can talk about WOSCOPS. It's 22 years old. It is part of the medical history and a very seminal article. I think they got creative because, as he mentioned. We have guidelines that support this treatment, but this is almost an unanswerable question, whether you say it's from ethics, or from equipoise, it was essentially unanswerable. So, they had to go back and take this historical study where practice patterns were different, to be able to look at this question. It was pointed out, there's pretty clear evidence in here and I think if you look at that during the five-year study period of the randomized period, pretty clear evidence that treating participants with LDLs above 190 without vascular disease certainly lowers cardiovascular disease events.
One of the best things about working on the editorial board is being able to work closely with authors, and I have to also thank Dr. Ray and his colleagues for being so gracious in working with us closely in some modifications as this went along. We hope, and I hope he feels this way, too, that at the end of the day, the product ends up being even better than where we started. That's our goal is to really help and work with authors in that way and they were incredibly responsive. The two things I thought they did really well that were insightful to the US guidelines and beyond. One is they also restricted to the group without diabetes, without ASCVD less than 7.5%, and some other parameters to really hone down on what we have in the current US guidelines and still the finding was consistent that the statin therapy benefited that group.
The other part was just acknowledging that the legacy part, the long-term effect, is really valuable. They published heavily in this area, but at that point, it becomes an observational component. It's not part of the randomized period. The reason that adds value, if you look at our guidelines above the age of 21, an LDL above 190 can be treated with a statin, there would be less controversy if your LDL was 200 and you're 55, but if you're 22 or 23, I think there may be more angst. That's where the long-term data is important, because we're not looking necessarily always at 10 years, but we're looking at 20 or 30 or 40 or 50 years. I think this does at least shed some light. I appreciate the study population was older, but a least it helps us look at maybe some of the long-term benefits.
If I may, Carolyn, I would love to ask Dr. Ray a question. Kaus, when you guys did this, the group with the LDL less than 190 had essentially similar benefit. The p-interaction was no. I think we have to acknowledge that the LDLs were higher in that group than what would seem because the lowest level was 155. Is it above 190, or should it be above 160 where we treat patients with statins?
Dr. Kausik Ray: Yes, and I really want to thank the editors, because there were certain things that you pushed us with analyses and I think that you could make the case that if you have a LDL cholesterol above 155, over a five-year randomized treatment period, there was a significant reduction in CHD and MACE as well. So, you could make that point that actually the cutoff should perhaps be pulled down even further to about 155. What's interesting is, these groups, when you broke them down, age was identical, BMI was identical, blood pressure, and everything else. The only thing that was different, really, was the LDL cholesterol, which impacted on total cholesterol. TGs, HDLs were absolutely identical. I think you could probably make the case.
I think the one thing that we didn't see, although it's observational in those with slightly lower LDL cholesterols, is that over the 25 year period, they seem to get slightly less mortality benefits. Now, that could be a chance finding, because it's observational. We don't really know the implications of that, but I think over a five-year period, this is the best evidence you're going to get for primary prevention, right?
Dr. Amit Khera: Agreed. The US guidelines do say above 160, it's a point of consideration. It can be a factor to consider as we think about treatment, so perhaps this helps bolster that point as well.
Dr. Kausik Ray: It's not just the American guidelines. In the European guidelines, when they use score, if you look at LDL cholesterol levels, the European case fatality 10 year risk is 2.5%, which is equivalent roughly to 7.5% fatal and non-fatal MI in the pooled cohort equation. There they still have diet and lifestyle, but it says, "Consider pharmacological," and one of the things I thought was really interesting is if you did a 10 year risk calculation in this group, 67% of the population with an LDL above 190, you would have said the predicted 10-year risk was below 7.5%, but the 10-year observed risk was double that. It was 15%. If you did the same thing for the group between 155 and 190, your ten-year risk predicted would be in most of these people, you would have said about 90% actually are less than 7.5%, so you wouldn't have given them a statin. But, their observed event rates in the placebo group was about 11%.
So, I think that it tells you if you have an isolated elevated cholesterol above 155, you're probably going to be underestimating risk if you're using global risk score, and perhaps a discussion with the patient about risks and benefits in the way that most of us try to do and citing data like this might encourage patients to actually start that therapy earlier, which most of us probably believe from genetic and legacy effect is probably beneficial. That's one of the other implications of this.
Dr. Amit Khera: This is why one has to read not just the abstract, but all the details, because there are so many kernels of interesting findings in this paper beyond just the highlights that we hit upon.
Dr. Carolyn Lam: Thank you both for just a marvelous discussion of an incredible paper that is really, really going to be extremely clinically relevant. We're so proud to be publishing this in Circulation this week.
Audience, you heard it right here. Don't forget to tune in again next week as well to Circulation on the Run for even more hot news.
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 take a deep dive into the issue of age and its association with outcomes of primary prevention ICDs in patients with non-ischemic systolic heart failure.
Yes, a long-awaited discussion from the Danish trial. That, in just a moment. First, here's your summary of this week's Journal.
The first original paper provides evidence of a true association between disturbed genetic imprinting and Preeclampsia. This paper is from co-first authors, Dr. Zadora, and Dr. Singh, and co-corresponding authors, Dr. Izsvak, from the Max Delbrück Center for Molecular Medicine; Dr. Hurst, from the University of Bath; and Dr. Dechend, from the Experimental and Clinical Research Center of Berlin.
These authors performed an unbiased analysis of genome-wide molecular data on raw characterized patient material, from normal controls, and patients with Preeclampsia, and identified DLX-5 as an imprinted target gene, with novel placental function in Preeclampsia. Due to loss of imprinting, DLX5 was upregulated in 69% of placentas from Preeclampsia patients. Levels of DLX5 correlated with the classical Preeclampsia markers.
DLX5 was expressed in human, but not in urine trophoblast, underlying the known human specificity of Preeclampsia. Finally, DLX5-induced overexpression if trophoblasts faithfully modeled Preeclampsia in a cell culture system. In summary, this paper shows that disturbed imprinting is common, and may play a causal role in Preeclampsia.
The next study affirms that stenosis severity is better discriminated using coronary invasive physiologic indices, than using coronary angiographic assessment. First author, Dr. Lee, corresponding author Dr. Koo, colleagues of Seoul National University Hospital, studied 115 patients with left anterior descending artery stenosis, who underwent both ammonia positron emission tomography, or PET, an invasive physiologic measurement.
Myocardial blood flow measured using PET, and invasively measured coronary pressures, were used to calculate microvascular resistance, and stenosis resistance. They found that both fractional flow reserve, or FFR, and instantaneous weight free ratio, or IFR, decreased as angiographic stenosis severity, resistance, and pressure gradient increased, and hyperemic myocardial blood flow decreased.
When the presence of myocardial ischemia was defined by both low hyperemic myocardial blood flow, and low coronary flow reserve, the diagnostic accuracy of FFR and IFR did not differ, regardless of cutoff values for hyperemic myocardial blood flow, and CFR. However, at any given stratum of a given stenosis, physiologic classification of stenosis severity using FFR or IFR showed better discrimination of a unique relationship between absolute myocardial blood flow, and pressure gradient, than anatomic classification using angiographic percentage.
In summary, by demonstrating coronary physiologic responses to coronary stenosis, these authors showed that stenosis severity is better discriminated, using invasive physiologic indices, than using angiographic assessment.
The next paper identifies a previously unknown angiogenic growth factor that can be enhanced therapeutically to repair the heart after myocardial infarction. This novel growth factor is endoplasmic reticulum membrane complex, Subunit 10, or EMC10, which the authors previously identified by bioinformatic secretome analysis in bone marrow cells.
In the current paper, from co-first authors Dr. [Rabel 00:04:35], and [Krof Clengobill 00:04:37], and corresponding author Dr. Wollert, from Hanover Medical Center, and colleagues, the authors investigated the angiogenic potential of EMC10, and its mouse homologue, in cultured endo fetal cells and infarcted heart explants. They found that EMC10 and its mouse homologue signal a virus, small GTAPases; p21-activated kinase; and p38 mitogen-activated protein kinase, to promote endothelial cell migration.
In mice with acute myocardial infarction, bone marrow derived monocytes and macrophages produced EMC10 endogenously, to enhance infarct vascularization, tissue repair, and heart function. Furthermore, subcutaneous treatment with recombinant EMC10 for one week, after myocardial infarction, augmented infarct vascularization and repair, and led to a sustained improvement in heart function and survival.
The next study is the first prospective randomized trial of screening for atrial fibrillation, with a smartphone-based, single-lead, electrocardiographic system in 1,001 patients, aged 65 years and above, with a CHA2DS2-VASc score of two and above, and without a history of atrial fibrillation.
In this paper, from first and corresponding author Dr. Halcox, from Swansea University Medical School, in the United Kingdom, and colleagues, patients were randomized, either to biweekly electrocardiographic recordings with the iPhone device, or to routine over a 12-month period.
The smartphone-based electrocardiographic approach was at least three times more likely to identify incident atrial fibrillation, than routine care, and at a cost of just over $10,000 per case identified, and was judged to be a highly acceptable approach in this group of patients. These results support consideration of evaluation in an appropriately-powered, event-driven randomized trial, to confirm the clinical and cost effectiveness of such an approach to stroke prevention in atrial fibrillation.
Well, that wraps it up for your summaries. Now for our feature discussion. The Danish trial really created a huge splash last year, when it was reported that a primary prevention ICD in patients with non-ischemic systolic heart failure, may not actually reduce all cause mortality. Something that we had, perhaps, taken for granted, and in fact, entered our guidelines.
Now, however, there was a pre-specified subgroup analysis at the time, that suggested a possible age-dependent association, between ICD and mortality, in the Danish trial. This week, we are so pleased to be discussing an in-depth analysis of the association between age and outcomes in the Danish trial.
I'm so pleased to have the first author of today's featured paper, Dr. Marie Bayer Elming, of Copenhagen, Denmark, as well as Dr. Sana Al-Khatib, who's not only an associate editor of circulation, but also the author of an accompanying, and she is from Duke, Durham, North Carolina. Welcome, ladies!
Dr. Bayer Elming: Thank you. Happy to be here.
Dr. Sana Al-Khatib: Thank you so much.
Dr. Carolyn Lam: Sana, could you start by framing why this paper is so important, and why we've been looking forward in anticipation to these results?
Dr. Sana Al-Khatib: Absolutely. As you know, data on the outcomes of primary prevention ICDs in patients with non-ischemic cardiomyopathy started emerging in the early 2000s, or so. Then in 2005, the sudden cardiac deaths and heart failure trial was published, that included a large number of patients with non-ischemic cardiomyopathy, and absolutely showed survival benefits from primary prevention ICDs in those patients. Of course, there were also patients with ischemic cardiomyopathy.
But really, that trial formed the basis of the guidelines, recommendations, that have informed our practice for the last 12 years, that basically tell us that we should consider implanting a primary prevention ICD in patients with non-ischemic cardiomyopathy, who have an EF of 35% or less, who have Class II or III heart failure symptoms. As long as they are on optimal care at the end, they have a reasonable life expectancy.
So that's what's we've been doing for years, and then, the Danish trial was published this past year, that really called into question the prior findings, and the current practice. Because Danish, as you stated, showed no survival benefit with primary prevention ICDs, but there are many aspects about the trial that people need to pay attention to, to put the results in perspective.
The fact that 58% of patients in the trial, in those arms, received cardiac resynchronization therapy ... the fact that the trial required that patients have an elevated NTproBMB level, to be considered for enrollment ... that may have biased the results toward a higher risk of non-sudden cardiac deaths, so on, so forth.
I think what was really interesting, and caught people's attention, when the paper was published, was this subgroup analysis that showed that younger patients may benefit more than older patients. I think, many of us, Carolyn, were really awaiting the results of a more dedicated analysis, looking at age in Danish, and Dr. Elming and her colleagues did a great job looking at this very closely in their paper, and showed great results, and probably will let Dr. Elming share those results with us.
Dr. Carolyn Lam: Yes, absolutely, Sana. Actually, I just wanted to echo how surprised everyone was, and the immediate thing was, "Oh, my goodness. What do we do with the guidelines?" Maybe we should get back to that later, and Marie, please share with us, what did you do, and what did you find this time?
Dr. Bayer Elming: The reason why we did this study was that, in this main Danish trial, age was the only one of the 13 pre-specified subgroups that had a significant treatment by a subgroup interaction. This suggested that a younger patient might have a survival benefit from ICD ... the implication, even though the overall study was neutral. So we wanted to further investigate this relationship between age and effective ICD implantation.
What we did was to look at the relation between age and effective ICD, and we found that there was this linear relation, for each year of younger age, that was associated with a reduction, a 3% reduction in the hazard ratio, for the benefit of ICD.
Also, we did this selection impact curve, which is a bit technical, but what it does is to describe the expected survival for the population, on as a whole, for the different age cutoffs for ICD treatments.
So, if we take into account, both the patients receiving an ICD, and those who did not, we could see why we would get the highest survival for the population as a whole. What we found was that, when no one in the population received an ICD, around 70% would survive.
If everyone in the population received an ICD, only 72% would survive, but if we chose 70 years as the age cutoff ... so, patients younger than 70 years received an ICD, and patients older than 70 years did not receive an ICD, we got the highest survival for the population, and 75% would survive.
Dr. Carolyn Lam: Thank you, Marie. What important results. So, maybe, still consider ICDs for primary prevention ... in our non-ischemic systolic heart failure, patients were less than 70 years old. Is it as simple as that, Sana? You wrote a beautiful editorial. Tell us, what are the clinical implications?
Dr. Sana Al-Khatib: This is an important question. Danish was an important trial, but in my mind, it truly doesn't refute the role of primary prevention ICDs in patients with non-ischemic cardiomyopathy. As I mentioned earlier, the majority of patients enrolled in Danish received a CRT device. And so, you end up questioning, what does that actually mean, for those patients who are not eligible for cardiac resynchronization therapy?
So, I actually believed that, and as you know, Carolyn, and maybe Marie knows, as well, there have been several meta analyses that have been published, combining data on patients with non-ischemic cardiomyopathy only, and excluding patients with cardiac resynchronization therapy from Danish, that have actually now shown, consistently, a significant improvement in survival, with a primary prevention ICD ... including one that was done by our group.
So, no, I don't think that, based on the results, we should say, "No, we shouldn't be offering primary prevention ICDs to patients with non-ischemic cardiomyopathy," and this beautiful analysis that was done by Marie and her group actually shows that, at least for those patients who are 70 years of age and younger, I think we should absolutely continue to consider them for the therapy, and offer them the therapy, if they're appropriate candidates.
Then, of course, if the patients are older than 70,, and they meet criteria for cardiac resynchronization therapy, I think it will be important for us to be talking to the patients about ... is the RTD with a defibrillator, versus a CRTP only, with a pacemaker, and talking about the pros and cons, and everything else? But in those patients who are older than 70, who don't meet criteria for CRT, I think more research is needed, to really understand the role of primary prevention ICDs in those patients. We definitely need more data there.
Dr. Bayer Elming: I definitely agree that, of course, for the patients older than 70 years were not candidates for CRT treatment. These patients, we do not know very much about 'em, and this study that we did, do not answer that question. Based on the Danish study, and this further analysis of the age inspection, the guidelines in Denmark also state that patients younger than, we say, 68 years, because that was the age cutoff used in the '08 Danish trial, you should definitely think of giving patients with non-ischemic cardiomyopathy an ICD.
But for the older patients, it depends on a variety of co-factors, such as co-morbidity, or frailty, and it should be an individual assessment of the patient. So, I agree with you, Sana.
Dr. Carolyn Lam: That's wonderful. Hey, just one more question. Sana, I'd like you to put on your AE hat, now, and sort of think with me. In circulation, we don't ... well, we're careful about publishing subgroup analyses, so to speak, right, of results. You articulated, in your editorial, reasons why this, perhaps subgroup analysis, may be different from others. Could you elaborate on that a bit?
Dr. Bayer Elming: Yeah, and absolutely, that's a great question. As you pointed out, I mean, you really ... the conventional wisdom in clinical research is to be careful, interpreting subgroup analyses. I think there are some strengths in this particular analysis, as Marie stated: "Here's what we specified." The other thing is, I believe that Marie and her group then came, and did their very robust statistical methods, and really, probably most importantly, if you look at their findings, they actually really align well, and support their main conclusion.
For example, looking at the fact that older patients had the higher presence of co-morbidities, that they had a higher level of [Co-BMP 00:17:00], they had had a longer duration of heart failure ... I mean, all those things most likely had an impact on their mode of death, really making it more likely for those patients to succumb to non-sudden cardiac death. I think the whole story makes a lot of sense.
Dr. Bayer Elming: If I can elaborate a bit on this, I think one of the important findings from the study is that we show that mode of death varied according to age. So, the rates of sudden cardiac death were almost similar, between the younger and the older part of the population. But the rates of non-sudden death were almost twice as high in the older part of the population. This is a really good explanation why the ICD implantations have less impact in the older patients.
Dr. Carolyn Lam: Yeah, because ICDs would definitely not be expected to reduce non-sudden cardiac deaths. Really, really, well put. Oh, thank you so much, Marie. We're so proud to be publishing your beautiful paper, as well as your editorial, Sana, and thank you for this great conversation.
Well, listeners, I'm sure you enjoyed that as much as I did. Thank you for joining us this week, and 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. Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore.
This week's journal is really special. It is the 2017 cardiovascular surgery-themed issue of "Circulation." To summarize this issue, I am so privileged to have the editors, Dr. Marc Ruel from University of Ottawa Heart Institute, as well as Dr. Timothy Gardner from Christiana Care Health System. Welcome gentleman.
Dr. Timothy Gardner: Hello.
Dr. Marc Ruel: Hi, Carolyn. Glad to be here.
Dr. Carolyn Lam: Thank you for another beautiful themed issue, Marc. I see that there are four general themes within this theme, if I may. The first of which are a collection of papers on coronary disease and coronary surgery. Could you maybe start by giving us an overview of that?
Dr. Marc Ruel: One of the main topics that have been looked at in the surgical-themed issue this year is coronary surgery. We all know well that 2016, 2017, the academic year was quite fertile in providing new information around coronary surgery, especially with the release of the ART trial had actually scientific sessions of the American Heart Association the last November with simultaneous publication.
Interestingly, the cardiovascular surgical-themed issue has several coronary papers and one that deals with essentially with graft failure, if you will. There's an in-depth review written by Mario Gaudino, who is well known and does fantastic work at Cornell, who essentially put a team together looking at several aspects of coronary graft failure. I guess we can say that these are looked in quite great depth, and they deal with several aspects of what would lead to a coronary bypass graft to fail.
First and foremost, Mario and the team look at the blood components. Then the artery and the native bed itself. Then they focus a lot on the conduit, not only the nature of the conduit being a venous versus arterial conduit, but also the way of storing the conduit prior to performing the bypass. Also, the technique that's used around the use of that conduit.
Finally, I'd say that the review culminates with the patient bioreactor, for lack of a better term, aspect. Endothelial dysfunction in the patient with diabetes, age, gender, hypertension, dyslipidemia, etc., all these things that do act as a significant substrate for the fate of the conduit vessel.
A very unique, I think, first-time, in-depth review that, certainly, the "Circulation" editorial team and reviewers were very excited about. I think this will be quite impactful and provide very, very detailed information for future research and future improvement and fate of the coronary graft conduits.
Dr. Carolyn Lam: And, Dude, I agree. It's the new look at perhaps a classic, old, central surgery, the cardiovascular surgery. Very nice, indeed.
Dr. Marc Ruel: Precisely, thank you. We also have a couple of important, seminal original papers within the realm of coronary surgery. In fact, these also deal, to some extent, with the fate of conduits and certainly how they work in the patient population in long ago bypass surgery.
One is a randomized control trial, a single center randomized control trial that was performed in South Manchester. It's called the VICO trial, a study comparing vein integrity and clinical outcomes. Essentially, the study looked at open vein harvesting versus two types of endoscopic vein harvesting for coronary artery bypass grafting.
The study was performed at a single center in England with three sound methods, having three groups of 100 patients who were compared with regards to the vein harvest technique. The primary outcome was with regards to actual vein integrity, looking at muscular damage and endothelial function and integrity on microscopy.
Surprisingly and actually quite reassuredly that there were very few differences between endoscopic vein harvest and open vein harvest. Certainly the investigators also looked, as one of their secondary outcomes, at quality of life. It was quality of life that was gained in patients who had endoscopic vein harvest versus those who had open vein harvest.
Overall, there was no difference in major adverse cardiac events. Therefore, showing at least in an internally valid fashion that these investigators at their center could do endoscopic vein harvesting as well as open vein harvesting.
Dr. Carolyn Lam: I know that there are other original research papers, perhaps. Would you like to highlight any of them?
Dr. Marc Ruel: Yes, for sure. Carolyn, there's also one more coronary surgery paper, which I wanted to highlight and that is the paper entitled, "Does Use of Bilateral Internal Mammary Artery Grafting Reduce Long-Term Risk of Repeat Coronary Revascularization?"
This is a multi-center analysis with first author is Iribarne from Northern New England. Essentially, seven medical centers got together and took about 20 years of consecutive CABGs with a total number of 50,000 operations, or just shy of 50,000 operations.
The median duration of follow-up was 13 years, and these patients were well matched together using a propensity matching scheme. I think this paper and this research is unique and of high impact. Even though it does have shortcomings of not being a randomized control trial, it is very welcome information, especially in light of the recent ART trial, which, as you know, did not show any difference at five years analysis between single and bilateral internal thoracic artery use.
The particularity of the Iribarne paper is that it is a very large data set up with close to 50,000 patients. It is multi-centered, therefore, it is real life. It is a consecutive series. The patients are extremely well matched, and it is remarkable to hear that the patients, in fact, had no difference in mortality until about five years after the operation.
As opposed to many previous series where single versus bilateral internal mammary grafting shows a mortality difference very early on, which always raises the suspicion of poor matching or confounding by indication, if you will, this paper did not have that.
Finally, the follow-up was quite long and at about six years, there was really a mechanistic signal with regards to repeat revascularization events, which seemed to match the difference in late mortality. There was no difference in early and five-year mortality, but afterwards as repeat revascularization events started to occur more frequently in the single mammary group, this was matched by a difference in mortality, as well.
I think a very useful, large, long follow-up mechanistically-based information that I think adds very significantly to the current information we have about bilateral versus single mammary use.
Dr. Carolyn Lam: Thank you, Marc. Two original papers, highlighted, dealing with really very important modern controversies in this area. Open vein versus endoscopic vein harvesting, single versus bilateral mammary artery bypass. Excellent.
Let's move on now to the next sub-theme, if you will. And that is the collection of papers on "Adult Congenital Heart Conditions," really, really an increasingly important and growing population that we're seeing. Tim, would you like to summarize maybe some of the highlights of the papers there?
Dr. Timothy Gardner: The first paper, as you point out, is focused on adult patients with repaired tetralogy of Fallot. This series came from the UK and it examines the course of almost 60 patients, at a mean age of 35 years following a repair of tetralogy as infants or young children, developed right heart failure and required pulmonary valve replacement.
This is a common scenario that we're seeing, successfully repaired children who appear to do well but as they get into their late 20s and 30s, their pulmonary valve function, which is often inadequate or not even present valve, require an intervention.
The important learning here is that pulmonary valve replacement, either surgically or by catheter technique, was shown to be highly effective in salvaging right ventricular function. That is based on imaging studies as well as hemodynamic studies of right ventricular function. There was an almost, in this group of patients, almost an immediate reverse remodeling of the right ventricle after placement of the valve, that continued to improve over time.
This was, I think, quite reassuring. There, historically, was a bit of a reluctance to operate on these patients as their right heart was failing, despite the fact that without some intervention to take the volume load off of the RV, the patients didn't do well. This is good news for an important group of patients who we are all seeing, who oftentimes present to the adult cardiologist because of this right ventricular failure problem. A nice, reassuring study.
Actually, the other two congenital papers are, again, focused on the infant. They both deal with the infant with hypoplastic left heart syndrome or single ventricle pathology. The first paper seems sort of specialized in terms of its focus, "The Optimal Timing of Stage-2-Palliation for Hypoplastic Left Heart Syndrome." This was a report from the NIH Pediatric Heart Network. They had a single ventricle reconstruction trial.
This network is comprised of about 10 North American centers, both in the U.S. and Canada and has provided excellent data about the management of pediatric heart disease but, in particular, the single ventricle trial has been excellent.
In this particular paper, they look at the optimal timing for stage-2 repair. Just to remind ourselves, the first part of the three-stage treatment for hypoplastic left heart syndrome is the Norwood procedure, which has to be done shortly after birth, as the patent ductus arteriosus closes and converts, essentially, the single right ventricle into the systemic ventricle.
The stage-2 comes along, usually done with a Glenn-type of shunt, increases pulmonary blood flow and stabilizes these infants until they can reach the age for, and the heart function for definitive repair. This has been a particularly difficult problem for the congenital heart surgeons. What is the optimal timing?
This study, which involved over 400 patients, identified optimal timing for the second stage between three and six months after the Norwood. I think this was very reassuring, is reassuring or supportive for the congenital heart community in terms of both patients and also good evidence base that a delay of three to six months does, in fact, produce the best transplant-free survival.
In fact, the other aspect of this observation was that infants who developed the need for another second stage operation sooner than that did not do well, and the reasons for the required earlier surgery could be failure of the initial operation or additional anatomic risk factors. But this, I think, was an important, large series, multi-center study that will prove to be very helpful in sorting out this complex timing of a three-stage repair.
Just to comment, again, for readers who don't deal with infant congenital heart treatments very often, there's been a remarkable amount of success over the last two decades in salvaging and saving these very difficult infants with the hypoplastic left heart syndrome. In fact, an additional paper in this surgery-themed issue, comes from the UK and is, in fact, a report on the findings from the UK-wide audit of the treatment of infants with hypoplastic left heart syndrome.
In fact, their findings, in this sort of real world, not in the Pediatric Heart Network trial group, is very similar. They found that infants who got to the second stage without additional refinement of the initial Norwood procedure and were able to be successfully treated with a Glenn shunt somewhere in the four-to-six-month age range, did well. They actually made the point that the anatomy was more of a determinant than anything else.
I think that this particular review will reinforce what the congenital heart surgeons have learned about optimal timing for this three-stage treatment of what previously were unreconstructable children.
Dr. Carolyn Lam: Thank you so much, Tim. Isn't it wonderful the way papers come in and they're actually complementary and consistent with one another. We're just so lucky to be publishing all of these great, high-quality, impactful papers in "Circulation."
Moving on, the next paper actually reminds us why this is a cardiovascular surgery-themed issue and not just a cardiac surgery-themed issue. Didn't we just say that earlier, Marc? This one is on abdominal aortic aneurysm treatment. A population-based landscape of this. Could you tell us a little bit more about that one?
Dr. Marc Ruel: Absolutely. Carolyn, you're entirely right. We must remember that "Circulation" is also about peripheral vascular disease, saying this earlier, or cardiovascular surgery and anesthesia consult also when it encompasses vascular surgery. Precisely to that effect, one of the papers in our cardiovascular surgical-themed issue is a landscape population based analysis from Finland that looks at the incidence of abdominal aortic aneurysm between the years of 2000 and 2014.
Finland has a population of about 5.5 million and remarkably has a very circumscribed healthcare system. They do not have an organized system of AAA care as some other countries have shown to have and potentially benefit from, but rather they have a treatment of this condition at several institutions, many of which may not be high volume.
I think the paper is remarkable is that it is very well nested in terms of a population. It provides a comprehensive landscape of where this condition has evolved to over the last few years. Obviously, we see in the results from the authors that the mortality has decreased quite a bit, but also the incidence, probably as a result of better control of risk factors. And also the incidence of rupture outside the hospital.
One thing that came out of this paper, as well, is a potential cohort of the benefits gained from developing an organized system of AAA care, from the reason that the mortality of AAA rupture in Finland was still quite high, despite this being a modern series. In fact, when you include ruptures, before arrival to hospital and at arrival to hospital, the overall mortality was almost 80% for ruptured AAA.
Perhaps one message that comes out of this is that there may be a benefit in having specialized centers dealing with these conditions, especially as they are in the process of rupturing. One last observation was, obviously, the increasingly prevailing role of endoscopic vascular repair in the treatment of this condition, which, in fact, has now surpassed open repair as the dominant method of elective repair.
I think, overall, a very comprehensive, well-nested, country-wide with good follow-up landscape of the AAA condition in a country that has essentially a similar socioeconomic status to much of the western world. Therefore, with external generalized ability to some extent.
Dr. Carolyn Lam: Exactly, and contemporary data. I really enjoyed that you paired those with an excellent editorial, as well. Finally, before we wrap this up, I have to ask Tim to comment on this next paper, and it's on ventricular assist device malfunctions, I love the title, "It's More Than Just The Pump." Of course, as a heart failure physician, this one's very close to my heart. Forgive the pun. But, Tim, could you tell us about that?
Dr. Timothy Gardner: This paper comes from the University of Pittsburgh and their artificial heart program. Robert Kormos is the first author and he's been one of the stalwart leaders in the use of LVADs and other pump devices. He reports on their experience with over 200 both HeartMate and HeartWare ventricular assist devices.
It was interesting when we reviewed this paper by the editors, there was some thought that maybe this was a little too engineering focused and so on, but I think the point of the paper is that, as they say in the very first line in their report, reports of LVAD malfunction had focused on pump thrombosis.
But they point out very appropriately that, in fact, controller failure, battery failure, cable failure and other causes of device failure, which can be critical and life threatening and so on, are engineering issues. It reminds us that when we're managing this difficult group of patients, and we're seeing many more patients today with getting LVADs than 10 or 20 years ago, we need to have the bioengineering abilities and resources available.
Even the surgeon and the critical care physician who is dealing with these patients either has to acquire this kind of knowledge or capacity himself or herself, or needs to have a good bioengineer nearby.
What's interesting, I think, that all of us define that these mechanical failures were more common in this pretty big experience than what we've more clinically worried about, which was thrombosis of the pump.
Dr. Carolyn Lam: Exactly. That's so wonderful. And you know it just leads me to really thank you both, Marc and Tim, for this extraordinarily excellent selection of original research, state-of-the-art and perspective articles and editorials on congenital, coronary, vascular and heart failure surgery. This really appeals not just to the cardiovascular surgeons but really to the vast readership of "Circulation."
Thank you for a wonderful themed issue and thank you for this great podcast.
Dr. Timothy Gardner: Well, thank you.
Dr. Marc Ruel: Thank you very much, Carolyn.
Dr. Carolyn Lam: Listeners, don't forget to tune in again next week.
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 feature discussion centers on the population burden of sudden death associated with hypertrophic cardiomyopathy. These are novel data from the ongoing Oregon sudden unexpected death study, results that may surprise you. Stay tuned and that's coming up right after these summaries.
The first original paper in this week's journal tells us that risk reductions from air pollution control yields health benefits comparable to the control of systolic hypertension and smoking in a high risk segment of the urban Chinese population. First author Dr Huong, corresponding author Dr Gu and colleagues from Fu-Wai hospital in Beijing China projected the life years gained if urban China were to reach one of three air quality goals. First, Beijing Olympic games level. Second, China class 2 standard. Third, the WHO standard. They further compared projected air pollution reduction control benefits with the potential benefits of reaching WHO hypertension and tobacco control goals.
Now to do this, the authors used the Cardiovascular Disease Policy Model: China, which is a computer simulation state transition mathematical model of coronary heart disease and stroke incidence, prevalence, mortality, non-cardiovascular deaths, and costs of health care in the Chinese population. They found that air quality improvement under the different scenarios could lead to a great health benefit, ranging from 241,000 life years gained to much greater benefits, benefits that were greater to or equal to the combined benefits of a 25% improvement in systolic hypertension control, and a 30% smoking reduction. Thus, the authors called for joint efforts of the whole society for air quality improvement in China.
The next study describes six differences and similarities in atrial fibrillation epidemiology, risk factors, and mortality in the community. First author Dr [Magnusson 00:02:42], corresponding author Dr [Schnabel 00:02:44] and colleagues from University Heart Center Hamburg Eppendorf studied 79,793 individuals without atrial fibrillation diagnosis at baseline from 4 community-based European studies, namely, FINRISK, DanMONICA, Molisani, and Northern Sweden, all followed for a medium of 12.6 years. They found that cumulative incidence increased markedly after the age of 50 years in men and after the age of 60 years in women. The lifetime risk was similar in more than 30% for both sexes.
Subjects with incident atrial fibrillation had a three and a half fold higher risk of death compared with those without atrial fibrillation. Among the classical risk factors, body mass index explained the largest proportion of atrial fibrillation risk. Six interactions were seen for the risk associations of body mass index and total cholesterol, wherein body mass index was associated with a greater risk increase in men than women, whereas total cholesterol was inversely associated with incident atrial fibrillation with a greater risk reduction in women than men.
The next study describes a novel circular RNA as a potential target in diabetic proliferative retinopathy. Circular RNAs are a novel class of non-coding RNAs that regular gene expression and they're characterized by closed loop structures with neither five-prime, nor three-prime polarity nor a polyadenylated tail. In today's study, first author Dr [Shah 00:04:33], corresponding authors Drs. [Yen 00:04:33] and [Zhao 00:04:36] from Shanghai Medical College Fudan University in China characterized the expression and regulation of the circular RNA, circHIPK3 in retinal endothelial cells and diabetic retinal vascular dysfunction.
CircHIPK3 expression was significantly up regulated upon high glucose stress in vivo and in vitro and regulated retinal endothelial cell function and vascular dysfunction by acting as an endogenous microRNA 30A-3P sponge that sequestered and inhibited its activity. In summary therefore, the circular RNA circHIPK3 plays a role in diabetic retinopathy by blocking microRNA 30A function, leading to increased endothelial proliferation and vascular dysfunction. These data suggest that the circular RNA may be a potential target for diabetic proliferative retinopathy.
The next study identified important new principles of endogenous chromatin structure that have key implications for epigenetic therapy. In this study from first author Dr Rosa-Garrido, corresponding author Dr Vondriska, and colleagues of David Geffen School of Medicine in UCLA, the authors examined changes in chromatin configuration in cardiomyocytes isolated from mouse hearts subjected to transverse aortic constriction or hearts subjected to Tamoxifen inducible cardiac specific excision of CTCF, which is a ubiquitous chromatin structural protein.
There was several important findings from this work. Firstly, the authors found that depletion of CTTF was sufficient to induce heart failure in mice and human heart failure patients receiving LVADs also showed increase CTCF abundance. Pressure overload or CTCF depletion selectively altered the boundary strength between topologically associated domains, which are regions of DNA in which physical interactions occur frequently. The authors showed that there were changes in the compartmentalization of active chromatin and inactive chromatin segments, which is a measure of genomic accessability.
Heart failure involved decreased stability of chromatin interactions around disease causing genes. In summary, these finding provide a high resolution chromatin architectural resource for cardiac epigenomic investigations and also demonstrate that global structural remodeling of chromatin underpins heart failure.
The final study is the first to provide insights into the fluid mechanics of transcatheter valve thrombosis. First author Dr Midha, corresponding author Dr Yoganathan and colleagues from Georgia Institute of Technology and Emory University in Atlanta analyzed post-procedural four dimensional volume rendered CT data of transcatheter aortic valve replacement, or TAVR patients, enrolled in the Resolve trial, excluding patients on anticoagulation. Patients were classified as having transcatheter heart valve thrombosis if there was any evidence of hypoattenuated leaf thickening. The authors studied the flow characteristics within the neo sinus which is formed followed deployment of a transcatheter valve into a native aortic valve.
The authors found that post deployment valve geometry and final implant position affected the flow within the neo sinus, which in turn, may affect the predisposition to thrombus formation. The impact of geometry and position varied according to the different valve types. A supra-annular transcatheter heart valve deployment resulted in a nearly seven fold decrease in stagnation zone size when compared to an intro-annular deployment. In addition, the in vitro model indicated that the size of the stagnation zone increased as cardiac output decreased. In summary, deployed transcatheter heart valve geometry may have implication on the occurrence of thrombosis and a supra-annular neo sinus may reduce thrombosis risk due to reduced flow stasis. While additional prospective studies are clearly needed, these results may help identify patients at higher thrombosis risk and aid in the development of the next generation of devices with reduced thrombosis risk.
Well, that wraps it up for our summaries. Now for our feature discussion.
Sudden death in hypertrophic cardiomyopathy has been and still is a very hot topic in cardiology. Of course it's understandable given all the high profile deaths that have occurred in young athletes ascribed to hypertrophic cardiomyopathy and the fact that these deaths may potentially be preventable with implanted defibrillators. However, we're so proud to have in this week's journal, some of the first data on the population-based burden of sudden death associated with hypertrophic cardiomyopathy. I'm so happy to have with us the corresponding author of this research letter, Dr Sumeet Chugh from Cedar Sinai Medical Center, as well as Dr Mark Link, associate editor from UT Southwestern. Welcome, gentlemen.
Dr Sumeet Chugh: Thank you.
Dr Mark Link: Thank you.
Dr Carolyn Lam: Sumeet, you know as I said in the introduction, sudden death in hypertrophic cardiomyopathy, we've talked about it a lot. There's been lots published. What makes your data so novel?
Dr Sumeet Chugh: There is indeed a large body of work related to hypertrophic cardiomyopathy but most of it came from registries. Probably what's a bit unique about our work is that it was done in one large, US community over a number of years.
Dr Carolyn Lam: Indeed. So population-based statistics, not just of hypertrophic cardiomyopathy, but of sudden death related to it, isn't it?
Dr Sumeet Chugh: That's correct, Carolyn.
Dr Carolyn Lam: I think the other thing that we were just actually chatting about is the fact that it's contemporary. Could you tell us maybe the period you're looking at and then give us your findings?
Dr Chugh: Yes. The study was initiated in 2002 and is now in it's 16th year, so this particular analysis was conducted between the time period 2002 and 2015. What we do in the process of this community-based work is that we track prospectively every cardiac arrest that happens in the community centered around Portland, Oregon in the USA. The work in performed in the process of doing a multiple-source ascertainment where we take the help of the first responders or the ambulance personnel, the hospital emergency rooms, as well as the police, and the coroner network. It's a fairly comprehensive way of ascertaining sudden cardiac arrest.
Dr Carolyn Lam: That is a very unique and valuable data set. Could you summarize the top line results, because they were rather surprising?
Dr Sumeet Chugh: We are already learning that over time, with more awareness, education, and modern management of hypertrophic cardiomyopathy, the risk of sudden cardiac arrest and the overall morbidity from hypertrophic cardiomyopathy may be on its way down. What this study is showing is, that actually the risk of sudden cardiac arrest and the burden of sudden cardiac arrest from hypertrophic cardiomyopathy in the community may be quite low. Those are the main findings.
Dr Carolyn Lam: Yeah. In fact, I was just so impressed because first of all, you excluded the individuals in this population and found that hypertrophic cardiomyopathy was responsible for 1 in 30 of the cardiac deaths, but that the incidence of the sudden deaths were 0.2 to 0.3% among these hypertrophic cardiomyopathy patients, perhaps less than others may have expected.
Mark could I bring you in on this for a moment? What do you think are the take home messages for something like this, because in a young and middle age population, is any rate really too low?
Dr Mark Link: I think this is great data because it encompasses an entire population, so it gets us good data on the true incidence of sudden cardiac death. In the study, if you look at the total number of patients that either had an ECHO or had an autopsy, about 5%, a little over 5% of them, had hypertrophic cardiomyopathy. Roughly 5% of the individuals dying suddenly, under age 60 are dying secondary to hypertrophic cardiomyopathy. That's the sort of data that we really didn't have before because we didn't have such a nice population-based study.
It was interesting also, they tended to be younger, 10 years younger than the others dying suddenly, so it was a younger cohort. They more often had ventricular fibrillation or ventricular tachycardia than the others dying suddenly. It really does give us some nice data on the true incidence of sudden death due to HCM in the community.
Dr Carolyn Lam: What I thought was also valuable was the fact that the diagnosis of hypertrophic cardiomyopathy was quite often missed prior to the cardiac arrest and I'm trying to wrap my head around about what that implies.
Dr Sumeet Chugh: That's a very important point, Carolyn. These findings also give us the message that our risk classification methodology continues to need more work. The fact remains that a significant proportion of patients with hypertrophic cardiomyopathy are also going to be asymptomatic. Sometimes they just don't come to our attention.
Another important point, however, that's related to this work is that there may have been during the course of this time period, at least a few patients in this community who would have received an implantable defibrillator and their sudden cardiac arrest would have been averted, so we're not able to count those individuals who were already found and managed.
Dr Mark Link: That's a very important point because if a person is found with HCM and has risk factors, they would get a implantable defibrillator. Those individuals would not show up in this database because they wouldn't die.
Dr Carolyn Lam: Mm-hmm (affirmative)-
That's a very, very important point. Thank you for highlighting that. I think it goes back to why these data are so important, because they are contemporary as well and we really need such estimates, so congratulations Sumeet and thank you for giving us these valuable data.
I'd like to switch tracks a little bit though, and point out this was a research letter, a big data set, important findings, but published as a research letter. Should I even say but? Mark could you comment a little bit about research letters in circulation versus original articles?
Dr Mark Link: We increasingly are using research letters in circulation for original research that drives home a basic single point. If that basic single point can be made in 1,200 words, we actually like the research letter format. It's a quick read, people remember it, it's cited. It is something that authors that we ask to turn a full length manuscript into a research letter, should be taking that as a positive sign, because that means that we're interested in the topic and would like to see it in print.
Dr Carolyn Lam: I completely agree and in fact, Sumeet, if I could ask you to weigh in. Sometimes it's harder, isn't it, to write a research letter than to write a full length manuscript? How was your experience?
Dr Sumeet Chugh: I have to admit that the first responses as you said, where you feel, "Oh, I've spent a lot of effort in writing this large paper, and now I have to squeeze it into 1,200 words," but the second thought for me was, "The fact is that this is a one bullet message and why not make it shorter and snappier as it is?" I think I've come around in the appropriate situation to appreciating this opportunity of writing a research letter.
Dr Mark Link: when you read the research letters, they're very succinct. I actually like them. They get the message across quickly and I think it's a great way to produce science and to show what you've done.
Dr Carolyn Lam: Yeah. The thing is that we also restrict to a single figure, or a single table and I cannot tell you how many times I've referred to that single figure because it usually tells the full story and it's beautiful summary.
So, listeners, you've heard about the research letters in circulation. Please have a look at them. I'm pretty sure that you will fall in love with the format just like we all have.
Thank you so much, Sumeet and Mark for joining me today. I'm afraid our time is up, but I've so enjoyed talking to you. Thank you, listeners, for following us today. 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 feature discussion this week centers on the temporal changes in natriuretic peptides preceding heart failure hospitalizations and patients at high risk. Data that are really novel and have implications for the way we perhaps monitor and categorize these high risk patients. Well, more soon right after these summaries.
The first original paper this week provides the first epigenome-wide association study in patients with heart failure. Now, epigenetics refers to biochemical DNA modification such as methylation of gene bodies, and post-translational modification of histones, which is increasingly recognized to play a crucial, regulatory interface between genes, environment, and the transcriptome.
The lack of availability of myocardial specimens from patients has been a major roadblock for elucidating the impact of such epigenetic changes on complex cardiovascular traits. However, in today's paper from first author, Dr. Meder, corresponding author, Dr. Katiz and colleagues from University of Heidelberg, Germany. The authors performed the first multi-omic study in myocardial tissue and blood of patients with dilated cardiomyopathy compared to controls.
They detected 59 epigenetic loci that are significantly associated with dilated cardiomyopathy, with three of them reaching epigenome-wide significance. 29 of these loci could be replicated in independent cohorts and authors further linked a subset of 517 epigenetic loci with dilated cardiomyopathy and cardiac gene expression.
Finally, they identified distinct epigenetic methylation patterns that are conserved across tissues. Thus representing novel, epigenetic biomarkers for heart failure.
The next study is the first to assess a diagnostic and prognostic value of cardiac myosin binding protein-C in patients presented with possible acute myocardial infarction or AMI. Cardiac myosin binding protein-C is a cardiac restricted protein that is more abundant than the cardiac troponins and is released more rapidly following AMI.
In today's paper, first author, Dr. Kaya, corresponding author, Dr. Marber and colleagues from the Rayne Institute In St. Thomas's hospital in London evaluated cardiac myosin binding protein-C as an adjunct or alternative to cardiac troponins in the early diagnosis of AMI in 1,954 unselected patients presenting to the emergency department with symptoms suggestive of AMI.
The final diagnosis of AMI was independently adjudicated in 340 patients. The authors found that concentrations of cardiac myosin binding protein-C at presentation were significantly higher in those with versus without an AMI. The discriminatory power for AMI quantified by the area under receiver operating curve was comparable for cardiac myosin binding protein-C to high sensitivity cardiac troponins T and I, and even superior to standard sensitivity cardiac troponin I. The use of cardiac myosin binding protein-C more accurately classified patients with a single blood test and to rule out or rule in categories in early presenters, meaning those with chest pain of less than three hours.
The improvement in rule in or rule out classification with cardiac myosin binding protein-C was larger compared with higher sensitivity cardiac troponins T and I. Finally, cardiac myosin binding protein-C was superior to high sensitivity and standard troponin I and similar to high sensitivity cardiac troponin T at predicting death at three years. Thus in summary, this paper shows that cardiac myosin binding protein-C at presentation provides discriminatory power comparable to high sensitivity troponins T and I in the diagnosis of AMI and may perform favorably in patients presenting early after symptom onset.
The next paper describes the discovery of a novel candidate cardiomyopathy or arrhythmia gene. First author, Dr. Barryfield, corresponding author Dr. McNally from Center of Genetic Medicine in Chicago and colleagues studied a family with dilated cardiomyopathy and associated conducted system disease in whom prior clinical cardiac gene panel testing was unrevealing. Whole genome sequencing however, identified a premature stop codon in the gene encoding a novel myo filament component, the myosin binding protein-H-like.
Having identified this gene, they turned to experimental approaches. The myosin binding protein-H-like gene was found to have high atrial expression with low ventricular expression. The truncated protein failed to incorporate into the myo filament. Human cell modeling demonstrated reduced expression of the mutant allele. Heterozygotes and nullumites exhibited a reduction in fractional shortening and increased diastolic ventricular chamber size, aberrant atrio-ventricular conduction and an increased rate of arrhythmia associated with the expression of the myosin binding protein-H-like in the atria, as well as in discrete puncta throughout the right ventricular wall and septum.
These findings therefore support that myosin binding protein-H-like truncations may increase the risk for human arrhythmias and cardiomyopathy.
Transplantation of cells into the infarctant heart has significant potential to improve myocardial recovery. However, low efficacy of cell engraftments still limits the therapeutic benefit. In today's paper, authors describe a method for the unbiased, in-vivo selection of cytokines that may improve Mesenchymal stromal cell engraftment into the heart. In this paper from first author, Dr. Bortolotti, corresponding author Dr. Giacca, and colleagues from University of Trieste in Italy, an arrayed library of 80 secreted factors were individually cloned into adeno-associated viral vectors.
Pools from this library were then used for the batch transduction of bone marrow derived Mesenchymal stromal cells ex-vivo, followed by intra myocardial cell administration in normal and infarctant mice. Three weeks after injection, the vector genomes were recovered from the few persisting cells, and identified by sequencing DNA barcodes that were uniquely labeled for each of the tested cytokines.
Using this novel, competitive, engraftment screening methodology, the authors identified that the most effective molecule was cardiotrophin-1 a member of the IL-6 family. Intra cardiac injection of Mesenchymal stromal cells preconditioned with cardiotrophin-1 preserved cardiac function and reduced infarct size parallel to the persistence of the transplanted cells in the healing hearts for at least two months after injection. Thus, preconditioning with cardiotrophin-1 might represent an efficient manner to improve the currently poor cell retention in patients treated with Mesenchymal stromal cell therapy.
The final paper presents results of the early myo trial, a non-inferiority trial comparing a pharmacoinvasive strategy with half-dose alteplase versus primary PCI in patients with STEMI, presenting six hours or less after symptom onset but with an unexpected PCI related delay.
First author, Dr. Poole, corresponding author, Dr. Hua and colleagues from Shanghai Jiao Tong University in China randomized a total of 344 patients from seven centers to a pharmacoinvasive arm or a primary PCI arm. They found that pharmacoinvasive strategy was non-inferior to primary PCI for the primary endpoint of complete epicardial and myocardial reperfusion after PCI defined as TIMI flow grade 3, TIMI myocardial profusion grade 3, and ST-segment resolution of more than 70%.
There was no significant differences in the frequency of the individual components of the combined endpoint. Infarct size and left ventricular ejection fraction were similar in both groups and there was no significant differences in 30-day rates of total death, re-infarction, heart failure, major bleeding events, or intracranial hemorrhage. However, minor bleeding was observed more often in the pharmacoinvasive group.
Thus the authors concluded that a pharmacoinvasive approach with reduced dose alteplase seems to offer effective and safe reperfusion in low-risk patients with STEMI with an unexpected PCI related delay. Further large, randomized control trials powered for clinical endpoints are needed.
Well, that wraps it up for your summaries. Now for our feature discussion.
The measurement of natriuretic peptides BNP, NT-proNP have certainly become the cornerstone of heart failure management. We measure these levels by guidelines in patients who are presenting with symptoms and suspected heart failure, in patients who are hospitalized. We measure them for prognostication purposes at discharge. However, what we don't really know is how the preceding changes in natriuretic peptides may precede heart failure hospitalization in patients who are at high risk of developing heart failure.
For example, patients with a recent coronary event or type-2 diabetes. And this is the very subject of our feature paper today, and I am so pleased to have the corresponding author of today's paper which is really a research letter. Dr. Brian Claggett from Brigham and Women's Hospital as well as Dr. Biykem Bozkurt who's our senior editor from Baylor College of Medicine.
Welcome both, and maybe I could start, Biykem could you let us know, what are the unanswered questions in heart failure relating to natriuretic peptides and how do you see this paper falling in, clinically?
Dr. Biykem Bozkurt: Carolyn, this is a wonderful I think prelude to perhaps preventing heart failure events. And as you are aware, we in the recent year changed our guidelines at the ACC, AHA, and the HFSA incorporating screening high risk patients for development of incident heart failure. And the study that resulted in this consideration was a STOP-HF trial which was utilizing natriuretic peptides in high risk patients to determine whether their closer follow up in a multidisciplinary fashion would result in earlier detection and prevention of heart failure, and which it did.
And this study I think is straddling the concept of high risk or stage A or B patients because they are individuals who have had heart attacks, coronary events, and they have type-2 diabetes so they are definitely high risk. And doing natriuretic peptides as an outpatient, whether that would predict the heart failure hospitalizations.
And in essence I think it's a good concept. Perhaps the challenging concepts are how often should we screen our patients, and what will be the threshold of the rise that would potentially make us act in either earlier diagnostic strategies, or management strategies. I think those are the two unanswered questions that remains.
How are we gonna screen our patients? Our high risk patients to determine when they are developing heart failure before they become symptomatic? So, what threshold are we going to use?
Dr. Carolyn Lam: That is a perfect set up. I just wanted to add as well in addition to STOP-HF there was the PONTIAC study in diabetics which is very relevant to today's paper that also sort of used NT-proBNP to risk stratify patients for prevention of heart failure. But neither of these studies talked about the temporal changes in natriuretic peptides. And I think a lot of the reason for that is, is that the methods, I mean the statistical methods to do that sort of thing are mind-blowing.
And so Brian, could you now please share with us what you did, the methodology and basically what you found before we discuss the two questions that Biykem brought up?
Dr. Brian Claggett: What was really interesting is the method that we came up with to look at these questions. It's something that we like to believe will be generalizable and can be used in other scenarios and for other biomarkers. But the idea that we have is that we are always used to thinking about the design of a clinical trial as being very regimented. So, you see a patient once at baseline, and then maybe six months later, and then maybe six months after that, and so on. And so it's hard to know what's going on, on a day to day or week to week basis.
But if you think backwards, and you think backwards from the time of any sort of event, because those events whether they're hospitalizations or MIs or death, they happen not on that same schedule. And so odds are at the end of a trial, you had a patient who came to a scheduled visit and then had an event the next day. And you probably had a patient who came in for a visit two days before an event, and another patient who came in a week before an event. So if you start thinking on that time scale, you can piece together all these different time frames when you do have data collected and try to reconstruct something that looks like an actual continuous natural history of what that biomarker would have looked like over say a two year period, if it had been measured continuously.
Dr. Carolyn Lam: So, tell us what you found. First of all, let's just make sure that everyone knows you were looking at the ELIXA cohort, right?
Dr. Brian Claggett: Yes, the data that we had available for this analysis comes from the ELIXA trials, it was 6,068 patients all with type-2 diabetes and a recent ACS event. Recent meaning within the last 180 days. And they were randomized placebo versus a diabetes drug, lixisenatide. And they were followed up for cardiac outcomes.
Beyond that, the natriuretic peptides were measure systematically at baseline, month 6, month 18, and month 24 in all patients who were participating in the trial. So this was the richest collection of a large number of patients being measured multiple times, systematically and not in just a sub-sample of the population. So, we felt like this was a great opportunity to learn something about what happens. What can you learn when you measure these natriuretic peptides over and over again.
And even more interesting than that, the fact that this wasn't a heart failure trial meant that some of the patients already had heart failure at baseline. Other patients didn't have heart failure, but as the trial went on, they developed or were hospitalized for heart failure for the first time. And so we were able to also look at differences between patients experiencing their first heart failure, versus those with more long standing disease.
Dr. Carolyn Lam: And that was very, very unique methodology that you spoke about. And I fully agree that it's going to be used more. I am staring at your beautiful figure one right now. That really, really says it all. Could you walk us through the results?
Dr. Brian Claggett: Sure, I think our key finding is that, I guess no matter when you measure patients. Patients with a higher level of NT-proBNP, or a higher level of BNP at any given time are going to be at higher risk of developing heart failure in the future.
But as we start looking at this as a temporal process, what we see is that there seem to be a noticeable acceleration in these increases, specifically in the last six months before development of heart failure. Or, before a hospitalization for heart failure. And that increase in the final six months seems to occur both in patients who had no prior history of heart failure and also in patients with a history of heart failure. So that six month window I think is something that we learned that we didn't necessarily know before.
Dr. Carolyn Lam: But, going back to Biykem's questions, do you think we have answers to how often we need to survey natriuretic peptides in these high risk patients and what threshold we need to act on?
Dr. Brian Claggett: I think both are very important. I think maybe the timing and the thresholds are somewhat separate questions. I think we're better able to answer the timing question. At the very least we can say that if dramatic changes are happening over a six month window that measuring patients only once every six months probably isn't enough. Whether that means it needs to be every three months, or two months, or one month, or something more than that, I think it's hard to know exactly what the right answer is. But I think we are confident in saying that things happen relatively quickly and we need to be measuring these things more frequently.
As far as the question of thresholds, I think that's maybe even a more difficult question. Or even the idea of a threshold means that we think that there's some magic number and I am not sure that we know for sure what's more important, the absolute number or is it the ... if someone starts relatively low and that relatively low number doubles over the course of six months. That might still be prognostically just as important as someone who's been consistently edging just below or just about that threshold level.
I'm not sure that we're confident enough to say that the changes, the speed of the changes, or the relative changes, or some absolute threshold is the most important thing to be paying attention to. But, I think where these two are related is the more ... that we can start to collect this data more frequently and be able to analyze it. I think that gives us a lot better chance of being able to successfully answer that question about thresholds.
Dr. Carolyn Lam: Indeed. Stuff for future work, huh? Biykem, what do you think?
Dr. Biykem Bozkurt: I wanted to point out two things from Brian's study which was quite interesting. One is the trajectory of the rise, or the delta changes in the natriuretic peptides was quite different in the patients with no history of heart failure compared to those with a history of heart failure. The trajectory, or the linear rise, or the delta changes were more prominent in the individuals with no history of heart failure. Probably intuitively expected so because their baseline levels are not as high as the individuals with history of heart failure.
So, it almost gives the impression that maybe in low low risk, the screening or the frequency may need to be lower, and if low, then probably the likelihood of the rise may be less. But those individuals who, as you said, are edging upward, then maybe the frequency may need to be higher and there may be perhaps a linear rise or a more prominent rise about six months before the incident event.
So, it's an interesting concept just to look at people's trajectories. But, as you said, probably individualization and monitoring or targeting may need to be individualized according to personal risk and other features. And one then wonders futuristically if this would be a concept that would be point of care testing maybe done by the patients similar to glucose monitoring. And in the event that we were to be able to carry the platform to self-test.
Dr. Brian Claggett: You're talking to a statistician, so I am always going to be in favor of collecting more data all the time. So I agree with that.
Dr. Carolyn Lam: Wow, what an insightful discussion. Thank you both for joining us on this podcast today.
Ladies and gentlemen out there, you heard it right here in Circulation on the Run. 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.
We know that excessive sedentary time is bad in terms of health outcomes, but does it matter how that sedentary time is accrued, whether in short or long bouts? Today's feature paper gives us some answers. More soon, right after the summary of this week's journal.
The first original paper in this week's journal provides insights into the mechanisms underlying neointima formation in arterial restenosis. Co-first authors, Dr. Cheng and Shi, corresponding author Dr. Li from Wuhan University in China, and their colleagues, performed an elegant series of experiments in which they demonstrated that interferon regulatory factor 4, or IRF4, which is a member of a family of key, innate, immune regulators known to play a role in cardiometabolic disease, actually protects arteries against neointima formation.
They further probed the mechanism underlying this protective effect and found that IRF4 promoted the expression of Krüppel-like factor 4 by directly binding to its promoter. Genetic over-expression of Krüppel-like factor 4 in smooth muscle cells reversed the neointima promoting effect of IRF4 ablation. Whereas, ablation of Krüppel-like factor 4 abolished the protective function of IRF4, thus indicating that the protective effects of IRF4 against neointima formation were Krüppel-like factor 4 dependent.
These findings suggest that the previously undiscovered IRF4 Krüppel-like factor 4 axis plays an important role in vascular proliferative pathology and thus may be a promising therapeutic target for the treatment of arterial restenosis.
The next paper highlights that high-spacial resolution in gene expression signatures can reveal new regulators, genetic pathways, and transcription factors that are active in well-defined regions of the heart.
Now we know that traditional genome-wide transcriptome analysis has been disadvantaged by the fact that the signals are derived from tissue homogenates. Thus, the authors of this current paper, including Co-First authors Dr. Lacraz and Junker, corresponding author Dr. Van Rooij from University Medical Center Utrecht in the Netherlands used tomo-seq to obtain genome-wide gene expression signature with a high spacial resolution, spanning from the infarcted area to the remote areas to identify new regulators of cardiac remodeling.
Using this technique, they identified SOX9 as a potent regulator of cardiac fibrosis. In vivo loss of SOX9 reduced the expression of many extracellular matrix genes, which coincided with a blended cardiac fibrotic response upon ischemic injury.
These data therefore were able to unveil currently unknown relevance of SOX9 as a key regulator of cardiac fibrosis, thus underscoring that tomo-seq can be used to increase our mechanistic insights into cardiac remodeling, and to help guide the identification of novel therapeutic candidates.
The next paper reports the primary results of the effect of ferric carboxymaltose on exercise capacity in patients with iron deficiency and chronic heart failure, or EFFECT-HF study, which is a randomized control trial of intravenous ferric carboxymaltose, compared to standard of care on the primary end point of change in peak Vo2 from baseline, to 24 weeks in patients with symptomatic, chronic heart failure with reduced ejection fraction and iron deficiency.
In this report from Dr. van Veldhuisen from University Medical Center Groningen and colleagues, intravenous ferric carboxymaltose was shown to significantly increase serum ferritin and transferrin saturation. At 24 weeks, peak Vo2 had decreased in the control group, but was maintained in the group receiving intravenous ferric carboxymaltose.
Although a favorable effect on peak Vo2 was observed with ferric carboxymaltose, compared to standard of care in the primary analysis, this effect was highly sensitive to the imputation strategy for peak Vo2 among patients who died.
They also reported that patient's global assessment and functional class, as assessed by New York Heart Association, improved on ferric carboxymaltose compared to standard of care.
Whether ferric carboxymaltose is associated with an improved outcome in these high risk patients, deserves further study.
The final study provides important long term clinical data to guide lead management decisions in patients with cardiac implantable electronic devices.
Dr. Pokorney from Duke University Medical Center in Durham, North Carolina, and colleagues, analyzed over 6,000 Medicare patients and found that device extraction was associated with a lower adjusted five year infection rate, compared with a cap and abandon strategy. There was a lower absolute five year mortality with extraction, but after adjustment there was no association between extraction and a lower five year mortality.
In summary, therefore, elective lead extraction for non-infectious indications in this Medicare cohort had similar long term survival, but lower risk of device infections at five years, compared to capping and abandoning leads.
Patient and provider preferences are critical to decision making when considering extraction versus capping and abandonment of leads.
Well, that wraps it up for your summaries. Now for our feature discussion.
For today's feature discussion, we are talking about sedentary time and a metabolic risk of having too much of it. But, today's paper is so interesting because it tells us that it's not just the total amount of sedentary time that may matter, but how we accrue the sedentary time. Very, very novel concept in my point of view and I'm so pleased to have the first and corresponding author of this paper, Dr. Keith Diaz from Columbia University Medical Center with us, as well as Associate Editor from Johns Hopkins, Dr. Wendy Post.
So pleased to have you both. Keith, could we just dive right into it? Tell us what population you were looking at, and what you found.
Dr. Keith Diaz: Sure, so we were studying a population of participants enrolled in the Hispanic Community Health Study, so it's a US populations of over 16,000 Hispanic adults. And essentially what we found was that sitting for prolonged bouts, so sitting for one, two hours at a time, was associated with poor glucose regulation.
Dr. Carolyn Lam: Well, yikes. I've actually been sitting for a few hours in a row right now, actually. I think these results are phenomenal, but could you maybe expand a little bit on the details, like how long is too long? And, how often a break needs to happen for you to see differences in the metabolic risk?
Dr. Keith Diaz: It's a good question and, to be honest, we don't know. I think that's where the research needs to head, but right now it seems to be that taking a break every 30 to 60 minutes could be beneficial. I think that's what we've found thus far.
Dr. Wendy Post: Keith, we were really excited to get your paper in. I think everyone on the Associate Editorial Board was especially interested in it because we can all relate. As Carolyn said, she's been sitting for a long time and when we have these meetings we have two hour meetings at a time and maybe we need to start saying that in the middle we should all stand up and take a break. So we can all relate to this.
But I think one the biggest questions that we had related to data itself, was the association between the total sedentary time and the sedentary bout duration. Maybe you can tell us a little bit more about those correlations in the interaction and tell us also how you also measure sedentary bout duration and total sedentary time in this observational cohort.
Dr. Keith Diaz: Sure, so I'll start with that latter question. So, we measured sedentary time [inaudible 00:09:32] subjectively. So we actually used an activity monitor called an accelerometer to see how sedentary they are. And how we quantified sedentary bouts is we just looked at how long consecutively a person sat without moving. That was considered sedentary bout. In terms of correlation, what we found is that there are very closely linked. So, people who sit for long hours during the day for total volume, also sit in long bouts. And so what we wanted to do was try to figure out and piece apart, which one is more important? When we're trying to ... If we're thinking about guidelines and what we should be doing about our sedentary time, is it important to reduce our volume or interrupt our bouts? And so what we found is that they're not independent, and that they're in many ways synergistic. And that the association of prolonged sedentary bouts with glycemic biomarkers varied according to how much total volume you sit and vice-versa.
Dr. Wendy Post: Can you expand a little bit more on that? So tell us about the interaction that you found between sedentary bout duration and total sedentary time.
Dr. Keith Diaz: Sure, so we did find that there was a specifically significant interaction between the two variables and so what we tried to do is actually categorize people as to whether they were high for both characteristics or high for just one of them. And so what we found was that those participants who are high for both, so they had high volume and sat in long bouts, they had the worst glucose regulation, and that those individuals that were high for just one of the characteristics had a little bit better glucose regulation. And so really what we thought the take home message was when thinking about how do we improve our sedentary behaviors is that it's targeting both. It's not sitting for large volumes during the day, but also making sure to take frequent breaks every 30 or 60 minutes.
Dr. Wendy Post: And tell us about the glucose measures that you included in your study.
Dr. Keith Diaz: Yep, we had a couple glucose measures. One we had people do a two hour glucose tolerance test, so they took a glucose drink and then we measured their blood sugar levels two hours after having that drink. We also measured their H1Ac levels as well as their fasting glucose and fast to link insulin measures from which we can then derive measures of something called HOMA IR, which is a measure of insulin resistance.
Dr. Wendy Post: And the associations that you saw were primarily with the HOMO IR and the two hour glucose levels but less with the hemoglobin A1c?
Dr. Keith Diaz: Correct.
Dr. Wendy Post: So it really appears to be that insulin resistance that's most affected by the total sedentary time and sedentary bout duration. Tell us about potential confounders and how you factored that into your analysis.
Dr. Keith Diaz: Yeah, there was quite a number of potential confounders between this relationship of sedentary behavior and glycemic biomarkers. One of them in particular that we were concerned about most were things like body mass index or exercise or physical activity levels. And so we took a look at what we adjusted for those confounders how the relationship changed. And what we did find was that there was an attenuation and association between sedentary behavior and the glucose markers, but there was also ... were still statistically significant. So suggestive that maybe they're partly in the pathway of body mass index or exercise but they didn't make the relationship go away. I should add that we looked at a couple other confounders, we looked at things like inflammation, C-reactive protein, as well as whole bunch of other measures of cardiovascular risk factors. I'll stop there.
Dr. Wendy Post: And what about the fact that study is cross-sectional, are there any caveats related to the study design that you'd like to point out to the audience?
Dr. Keith Diaz: Yeah, I think that's an important point, that this is cross-sectional, so by no means can we infer causality that sedentary behavior causes glucose dysregulation, it's just purely an association. So I think anyone listening to this podcast should keep that in mind when reading this paper or listening to this podcast.
Dr. Wendy Post: So if you were writing the next set of guidelines what would you recommend in terms of how you implement these findings into guidelines? Not to imply that we think that these cross-sectional observational data mean that we're ready to change guidelines but, if these were replicated in randomized trial or some other more objective data study design, how do you think we should use these results to change our behaviors?
Dr. Keith Diaz: I think these guidelines point ... or, with the current guidelines are, sit less, move more, where the guidelines that came out from AHA in October of 2016. In part, they were not as specific because we don't have quite the quality of guidelines or data that we need for more qualitative guidelines, or quantitative guidelines. I think if we're able to replicate these data with [inaudible 00:14:10] or point us towards at least is, also, that we should be interrupting our sedentary bouts. And so what I'd like to see hopefully if we can replicate something I'd like guidelines that say every 30 minutes or every 60 minutes of sitting you should stand up and move. And hopefully with future studies that are coming out that we can make them even more specific and something along the lines of every 30, 60 minutes you stand up and walk for 5 minutes or you just stand up for 1 minute. That's where I'd like to see the science head and I think this study points us in the that direction of maybe we have to start thinking about breaking up our sedentary bouts.
Dr. Carolyn Lam: All right you guys, I don't know about you, but I am literally standing up right now while I'm listening to you both. This is so interesting and I love the way, Wendy, you reflected the robust discussions we had as team when we were working through this paper. Congratulations again, Keith, for just this remarkable paper. Actually, maybe I could just ask, Wendy, what do you think? What do you think our next steps that may need to get these kinds of recommendations, perhaps into guidelines?
Dr. Wendy Post: I think as was alluded to before, these are observational data so they're important for hypothesis generation, but really to have evidence that would lead to changes in guidelines maybe having a randomized trial, where obviously you can't have very hard outcomes, but randomized trials of some duration that could potentially lead to changes and important outcomes, would then maybe lead to changes in guidelines. But there isn't anything that we would lose from trying to implement these kinds of behavior, changes into our lifestyle since the downside and the risk is pretty low. So even if they don't make the strongest level of evidence at this point, I think we can still all be mindful of this and so.
One thing that we've been trying to do in our preventive cardiology group at Hopkins is trying to implement walking meetings. In fact, I just had an email discussion with one of my colleagues about meeting tomorrow and she said, "Well, where do you want to meet?" And I said, "Well, why don't we go for a walk? The weather should be nice." And so I think if we're all mindful of trying to, not only increase our amount of physical activity, but trying to limit the sedentary bout duration by being creative and trying to change, sort of, long standing traditions of having meetings sitting in an office, then that could be helpful.
So, just something for our audience to think about as well.
Dr. Carolyn Lam: That's brilliant. You know, the one thing that I was thinking, though, just thinking about the reception of these data in my country, in where I practice, in Asia. This was a purely Hispanic or Latino population. I suppose there is a perception that that population may be predisposed to cardiometabolic disease and so on, and so you know, what's the applicability to us in Asia? So, I'm really happy, particularly to hear how you've taken it on. I mean, it's a simple thing, why not, right? Just to be more active. There's surely can't be something wrong with that. What do you think of that?
Dr. Wendy Post: Totally, I think it's important to emphasize the unique nature of these data and that they come from a Hispanic study, which is a really important addition to our literature in epidemiology and cardiovascular disease and certainly there are significant differences in lifestyle among different communities within the United States and across the globe, as you've experienced having lived in different countries. And so, I think we need obtain more data about how there might be differences based on various traditions and different lifestyles, and try to target those who are at greatest risk.
Dr. Carolyn Lam: Keith, did you have anything to add to that?
Dr. Keith Diaz: Yeah, I think Wendy is right on and certainly I don't think we have any reason to suspect that sedentary behavior acting differently in Hispanics versus other populations, and so I still think going forth with this notion that we all should be reducing our sedentary behaviors is important to highlight.
Dr. Carolyn Lam: Fantastic. Well, thank you both for a really wonderful discussion. This is really cool, I think a lot of people will be talking about this.
Listeners, you've heard it first, though, in Circulation on the Run. Thank you for joining us today and 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. Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore.
Today's issue features striking results from the ASSERT 2 trial of the prevalence of subclinical atrial fibrillation detected with implantable monitors in a group of high-risk older individuals. Much more soon, right after these summaries.
The first original paper in this weeks' journal shows for the first time that myocardial edema, in the week after STEMI in humans, is a bimodal phenomenon. First off, there is Dr. Fernandez Jimenez and Barreiro-Perez, corresponding author Dr. Ibañez, and colleagues from CNIC in Madrid, Spain, evaluate that the time course of edema reaction in 16 patients with anterior STEMIs successfully treated by primary angioplasty compared to 16 matched controls using cardiac magnetic resonance and assessing its implications for myocardium at risk quantification. The STEMI patients were scanned serially within the first three hours after reperfusion and at, one, four, seven and 40 days, while controls were scanned once. Furthermore, they performed an experimental study of 20 pigs undergoing 40 minute ischemia reperfusion, followed by serial cardiac magnetic residence exams at 120 minutes, one, four and seven days after reperfusion.
The authors found that am initial wave of edema appeared abruptly at reperfusion, but it was significantly attenuated by 24 hours. The initial wave of edema was followed by a second or differed healing related wave of edema several days after reperfusion, reaching a plateau around four to seven days after myocardial infarction. Of note, cardiac magnetic resonance myocardium at risk quantification at 24 hours post-reperfusion severely underestimated the infarct size.
In summary, post-MI edema in patients follows a bimodal pattern, which affects cardiac magnetic resonance in estimates of myocardium at risk. The dynamic changes in post-STEMI edema, highlight the need for standardization of cardiac magnetic resonance timing to retrospectively delineate myocardium at risk and quantify myocardial salvage. According to the present clinical and experimental data, a time window between day four and seven, post-MI, seems a good compromise for standardization. However, further studies are needed to study the effect of other factors on these variables.
The next paper sheds light on molecular mechanisms underline the progression of atherosclerosis, involving multiple inflammatory events, as well as the counteraction by inflammatory responses in cells such as the endothelium, circulating monocytes and resident macrophages in the arterial wall.
Co-first authors, Dr. Li and Martin, corresponding author Dr. Shyy from Xi’an Jiaotong University Health Science Center and University Health Science Center and University of California, San Diego and colleagues, analyzed RNA seek data to identify cholesterol oxidation and e-flux genes regulated by Kruppel-like factor 4, which is a key anti-inflammatory transcription factor. They found that Kruppel-like factor 4 upregulates cholesterol 25 hydroxylase and liver X receptor in vascular endothelial cells and macrophages. In further in vitro and in vivo experiments, they show that access enhanced reverse cholesterol transport from the vascular wall, mitigated inflammation through suppression of sterile regulatory binding protein two and NOD-like receptor family hiring pyrin domain containing protein three inflammasome in endothelial cells and also promoted cholesterol e-flux in M1 to M2 transition in macrophages.
In summary, Kruppel-like factor 4 trans-activates cholesterol 25 hydroxylase and liver X receptor, promoting the synergistic effects between individual cells and macrophages to protect against atherosclerosis susceptibility, and this may therefore be a therapeutic target for cardiovascular disease.
The next study provides data on the safety and efficacy of a novel cobalt alloy-based coronary stent eluting the antiproliferative agent, ridaforolimus, for treatment of patients with coronary artery disease.
Dr. Kandzari from Piedmont Heart Institute in Atlanta, Georgia and colleagues, reported the primary results of the bionics trial, which was a prospective international, one-to-one randomized trial conducted to evaluate in a noninferiority design, the relative safety and efficacy of ridaforolimus-eluting stents compared to slow release zotarolimus-eluting stents among 1,919 patients at 76 centers undergoing PCI. At 12 months, the primary endpoint of target lesion failure was 5.4% for both devices, thus meeting the prespecified criteria of noninferiority of ridaforolimus stent compared to the zotarolimus stent.
Angiographic and intravascular ultrasound measures of restenosis, late lumen loss and nepintimal hyperplasia measured at 13 months, were similar in both devices. Treatment with the ridaforolimus-eluting stent resulted in low rates of myocardial infarction, repeat revascularization and stent thrombosis, and results were consistent in predefined patients and lesion groups. The authors therefore concluded that these results support the safety and efficacy of ridaforolimus-eluting stents in patients representative of every day clinical practice.
Well, that wraps it up for your summaries. Now, for our future discussion.
Today for our future discussion, we are going to talk about a true global public health problem. It's a condition that affects 33 million people worldwide, a number that is expected to double by 2050, and what we're talking about is atrial fibrillation. Those are the numbers of just what we know of detected atrial fibrillation, but today's paper deals with silent subclinical atrial fibrillation and the results of the ASSERT 2 trial. I'm so pleased I have the first and corresponding author with us today, Dr. Jeff Healey from Population Health Research Institute at McMaster University in Hamilton, Ontario. Welcome, Jeff.
Dr. Jeff Healey: Good morning.
Dr. Carolyn Lam: Also on the show today is Dr. Sami Viskin, associate editor from Tel Aviv Medical Center. Hi, Sami.
Dr. Sami Viskin: Hi. Hello, everybody.
Dr. Carolyn Lam: Jeff, from ASSERT to ASSERT 2, could you give us a bit of the picture of what made you do ASSERT 2 and what have we learned?
Dr. Jeff Healey: The ASSERT trial was a large 2,500 patient trial in patients in with pacemakers and also implantable defibrillators and it was really an easy first place to study this entity of sub-clinical atrial fibrillation because, of course all of these patient had implanted devices with electrodes in their atrial where they could report all of the internal activity continuously for many years at a time. This was done with really no incremental costs or inconvenience to the patient, the data were already being collected, so in ASSERT we asked the question, how common is atrial fibrillation as it is not detected clinically and is it associated with stroke? What we found was that over time, somewhere between 30% and 40% of patients with an implemented device developed atrial fibrillation, which we termed subclinical atrial fibrillation, because this was not detected by the usual clinical mean. Great results, very interesting, but begged the question, is this a unique entity that we see only in pacemaker patients or if you just took older individuals in the more general population, would you see subclinical atrial fibrillation as well? That was really the impetus for doing that ASSERT 2 trial in patients who are over the age of 65, had cardiovascular condition, placed them at increased risk or stroke in atrial fibrillation, but did not have implanted devices.
Dr. Carolyn Lam: Indeed, Jeff. That's a beautiful set up. The ASSERT was really quite a landmark study suggesting that what we know as clinical may be just the tip of the iceberg, isn't it? Now you've extended it, and I think it'd be really important for the audience to understand that ASSERT 2 was really a high risk cohort. Could you maybe tell us a little bit more of what you did and what more we learned?
Dr. Jeff Healey: Sure. These were typical patients who might be attending a cardiology clinic, an outpatient general medicine clinic who did not have pacemakers and did not have any history of atrial arrhythmias, but you're right, they were high-risk. These were patients over 65 who have had clinical risk factors, things like hypertension, or diabetes, but also some other marker of increased risk such as a BNP that was elevated or left atrial enlargement.
Dr. Carolyn Lam: Yeah and your findings were so striking. Tell us.
Dr. Jeff Healey: What was quite was surprising was, indeed, we found that in the non-pacemaker, non-defibrillator population from ASSERT 2, we also found high prevalence of subclinical atrial fibrillation. This was really quite surprising. In fact, it was many times higher than we had predicted. We found that over time, the annual risk of developing atrial fibrillation in this cohort was 34.4% per year, which is truly astounding number of patients who developed atrial fibrillation.
Dr. Carolyn Lam: That's like one in three of such patients experiencing at least one of these episodes lasting at least five minutes? That's really impressive.
Dr. Jeff Healey: It was high. You could look into that study and find groups where the risk was even higher, so we chose to cut off left atrial volume of 58 millimeters and not correspondent with the median volume of the population series of Olmstead County for people over the age of 65 who came in for an echocardiogram, and that was the minimum left atrial size to get into the trial. If you then looked at within the ASSERT 2 trial and looked at the volumes within the trial, somewhere around 72 1/2 milliliters, if you looked at the patients who had the top of atrial size, that risk was as high 50% per year, so one in two.
Dr. Carolyn Lam: Another thing I noticed though about your results is that the frequency of these episodes, it's not that frequent, and so what we would do typically in a 24-hour monitoring or even a seven-day monitoring would have captured only a small proportion of these. Isn't that the case, Jeff? Could you give us some numbers there?
Dr. Jeff Healey: Yes, of course. The episodes that qualified were at last five minutes in duration, we then do longer episodes in course, but these were much less frequent in the single digit percent risk, and what we found was there were, as you say, quite infrequent. So with the standard 24-hour halter monitor, for example, you would have had a very low pickup. It really goes to show that the longer you monitor, the more you will find. I think that's the key message out of this study and other studies like it.
I think conversely, you also have to realize that the more you look, or the harder you look, you may be uncovering atrial fibrillation that behaves differently than atrial fibrillation you find, for example, in the single 12 lead ECG. We have found, and others have found, that the risk of stroke we find when we would have short episode picked up only with long term continuous monitoring is real but it's much lower than we see with atrial fibrillation that was picked up by ECB where patients are presenting in emergency rooms stroke with symptoms.
Dr. Carolyn Lam: That's such relevant points, and it really brings up the unanswered questions perhaps, exactly what is the correlation with stroke risk? What should we do about it? Sami, I'm sure you have other questions when you handle this paper and we had so many discussions among the editor, would you like to just start the ball rolling in some of these considerations?
Dr. Sami Viskin: Well, actually, we understood from the beginning of the study was not powered to show any difference in outcome by intervention, by treating any of these patients that had discovered atrial fibrillation with anticoagulation, so we took this paper as what it is, a paper that shows the unexpectedly high privileges of atrial fibrillation in patients who have neither symptoms nor electrocardiographic documentation of atrial fibrillation when they undergo implantation of our recording device. So we took this paper for what it is, a very interesting finding that opens the door for new studies, testing perhaps the value of intervention with anticoagulation at an earlier stage.
Dr. Carolyn Lam: Yeah, I agree. I'd love to hear Jeff’s thoughts on what those next steps may be, but just to point out to the audience, I mean, at the moment, our decisions on whether to anti-coagulate, like the CHADSVASC score and so on, doesn’t really take into account the type of atrial fibrillation or the duration of atrial fibrillation? Does it? What do we do now? What do we do in the context of the fact that results, like the COMPASS trial, that maybe just based on the presence of vascular disease, we should anti-coagulate, right? Jeff, how about your thoughts? What are the next steps?
Dr. Jeff Healey: You're right. I mean, is there a value for empirically anticoagulating individuals. That's really going to boil down to the individuals with an absolute risk of stroke and how well they do on anticoagulants. Good question.
In the post-stroke world or post-cryptogenic stroke, which we now report to as [inaudible 00:16:48], these individuals are being evaluated with two large clinical trials, looking at this idea of just empiric anticoagulation with low dose, NOAC in comparison to aspirin. These trials are ongoing, and they expect to report findings by the end of 2018.
In the general population, no such large scale trial is ongoing at the present time. You mentioned COMPASS and the big COMPASS results were clearly a big result at the European Society meeting, but it must be clarified that the dose of NOAC or rivaroxaban used in COMPASS was not the typical dose that we would use in the treatment of patients with atrial fibrillation, so much lower. I think we have to be careful when we're talking about doses that may be different 5 to 10 fold and what is then coagulating a patient and what is not. I think, certainly, I would not consider the COMPASS tests right now to be an effective atrial fibrillation dose, but as we've discussed, subclinical atrial fibrillation is different and we may have further data in the future.
Now, how do we get there? I think many people are aware of two ongoing trials, the ARTESIA trial, which is run by our group, the NOAH-AF Trial run by Kirchof and the group from Birmingham and the AF-NET organization, and these two ongoing trials have taken this question back again, so the pacemaker population that we are enrolling thousands of patients with pacemakers and defibrillators who have these short episodes, and they're being randomized treatment with a full dose new oral anticoagulant vs aspirin. These trials are ongoing, and I think these trials and the pacemaker population will actually give us the answer to what is the risk benefit for treating, so interesting course of event. We started in the pacemaker population to show there was risk for these short episodes, that this was hotly debated 10 - 15 years ago, and now we take ASSERT 2 and other trials into the non-pacemaker population to show that this is actually a problem for older individuals in general, and now the third step, go back into the pacemaker clinic again and to do trials to study the effectiveness in therapy.
Dr. Carolyn Lam: Great point and great takeaways. How about, Sami? What do you think would be the take-home message for clinicians at this moment based on what we know now and based on this new data?
Dr. Sami Viskin: Well, the message is clear, the message is that atrial fibrillation is far more prevalent than what we think it is, the message is that for every event of atrial fibrillation that we feel we probably have many events that we don't feel we should be distrustful about judging the decision to anti-coagulate or not based on symptoms, and I'm referring now to patients who already have one event documented of atrial fibrillation and are waiting until they feel the next one, before they start taking anti-coagulations. This is another warning about how we should be careful about trusting symptoms when deciding to treat and when not to treat. I just said this opens a new door for a new line of studies, looking at how early to intervene with anticoagulation, what dosage should be used for these patients who probably have lower burden of atrial fibrillation. If you can see that the patients who have atrial fibrillation documented on the electric cardiogram, as patients who simply have a higher burden and therefore they are more likely to come up with documentation on a regular ACG, so perhaps those only have subclinical atrial fibrillation have a lower burden, perhaps they can benefit from lower doses of anticoagulation, but these are all fit, that need to be proven by trials.
Dr. Jeff Healey: It is not only an issue for implanted devices but with the implantable cardiac monitors, this is now relevant for many other patients who have these devices implanted for things like syncope, but also there's been a lot of progress in the last 5 to 10 years on surface-attached based monitors or other types of monitors that can be with patients for days, weeks and even months, and we're all grappling with this in clinical medicine, what to do with a person with 25 beats of an atrial tachycardia or 37 seconds on a 30-day monitor? It's all an issue of the density, the burden of arrhythmia, and we do believe there is some gradience in the risk of stroke ... You're right, the treatment is not obvious, but we should take our treatment for patients who are in atrial fibrillation a lot or all the time, and simply apply it upstream like, that we may have very different treatment or approaches that are more tailored to individual patient risk.
Dr. Carolyn Lam: Thanks, Jeff, and thank you so much, Sami. Congratulations, Jeff. We discussed a lot of other questions that need to be answered, but you've really opened the door to look at some of these questions with your paper today and we're really very proud to be publishing your paper in this week's journal.
Thank you very much, listeners for joining us 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 featured discussion today centers on new data from the Framingham Heart Study that addresses the question of the prognosis of pre-hypertension among individuals who never progressed to hypertension as well as the role of early versus late onset pre-hypertension in this context. Well, more soon, right after your summary of this week's journal.
The first original paper provides mechanistic insights on the relationship between low and oscillatory wall shear stress, together known as disturbed flow, and atherosclerotic arterial remodeling and stiffness. Co-first authors doctors Kim and Pokutta-Paskaleva, co-corresponding authors Dr. Brewster and Jo from Georgia Institute of Technology in Emory University in Atlanta, Georgia used a novel mirroring model of disturbed blood flow to stimulate arterial stiffening through collagen deposition in young mice. They discovered a critical role for Thrombospondin 1, or TSP1 in activating TGF beta and stimulating arterial stiffening, all of which was significantly attenuated in the TSP1 knockout animal.
Blockade of TSP1 activation of TGF beta decreased the up regulation of pro-fibrotic genes that contributed to arterial stiffening. Furthermore, they show that TSP1 localized to regions of disturbed flow in arteries from patients with peripheral artery disease and these arteries had similar increases in collagen gene expression. Thus, this work links TSP1 up regulation to arterial stiffening and identifies TSP1 as an important promoter of pathologic arterial remodeling in peripheral artery disease.
The next study provides international insights on the degree to which secondary prevention treatment goals are achieved in clinical practice among patients with diabetes and cardiovascular disease. First and corresponding author, Dr. Pagidipati from Duke Clinical Research Institute at Duke University School of Medicine in Durham, North Carolina, looked at 13,616 patients from 38 countries with diabetes and cardiovascular disease in the TECOS trial. They found that only 30 percent of patients met all 5 secondary parameters of aspirin use, lipid control, blood pressure control, angiotensin-converting enzyme-inhibitor, or ARBUs, and non-smoking status.
Only 58 percent of individuals with diabetes and cardiovascular disease attained blood pressure control. Furthermore, the degree to which secondary prevention goals were met in this trial varied by the world region and country. In summary, patients with diabetes and cardiovascular disease are still being undertreated globally with respect to secondary prevention, and especially with regard to blood pressure control. These gaps in care provide clear opportunities for improvement in this high risk population.
The next study is the first to directly compare data from an electronic data research network to a large cardiovascular disease cohort. First author Dr. Ahmed, corresponding author Dr. Allen from Northwestern University in Chicago and colleagues sought to evaluate the degree of agreement of electronic data research networks compared with data collected by standardized research approaches in a cohort study. To achieve this goal, authors linked individual level data from the multi-ethnic study of atherosclerosis, or MESA community based cohort with Healthlink, a 2006 to 2012 database of electronic health records from 6 Chicago health systems.
They identified areas of agreement and disagreement between blood pressure, cardiovascular risk factor diagnosis, and cardiovascular events between the two data sources. The correlation was low for systolic blood pressure, compared with MESA, Healthlink overestimated systolic blood pressure by 6.5mm mercury. Conversely, there was a high correlation between body mass index in MESA and Healthlink. Healthlink underestimated body mass index by 0.3 kilograms per meters square.
Using ICD-9 codes and clinical data, the sensitivity and specificity for Healthlink queries for hypertension were 82.4 percent and 59.4 percent. For obesity these figures were 73 percent for sensitivity and 89.8 percent for specificity and for diabetes they were 79.8 percent for sensitivity and 93.3 percent for specificity.
Finally compared with adjudicated events in MESA, the concordance rates for myocardial infarction, stroke, and heart failure were at 41.7 percent, 61.5 percent, and 62.5 percent, respectively. These findings therefore illustrate the limitations and strengths of electronic data repositories compared with information collected by traditional standardized epidemiologic approaches for the ascertainment of cardiovascular risk factors and events.
The next paper helps physicians and patients to make an informed decision about whether or not to stop low dose aspirin use. First and corresponding author Dr. Sundstrom from Uppsala University in Sweden and colleagues investigated whether long term low dose aspirin discontinuation increased the risk of cardiovascular events in a cohort study of more than 600,000 users of low dose aspirin for primary or secondary prevention in the Swedish prescription register between 2005 and 2009.
They found that patients who discontinued aspirin had a 37 percent higher rate of cardiovascular events than those who continued, corresponding to an additional cardiovascular event observed per year in one out of every 74 patients who discontinued aspirin. The risk increased shortly after discontinuation and did not appear to diminish over time. Thus, in long term users, discontinuation of low dose aspirin in the absence of major surgery or bleeding seemed to be associated with a more than 30 percent increased risk of cardiovascular events, thus adherence to low dose aspirin treatment in the absence of major surgery or bleeding may be an important treatment goal.
The final study raises the possibility of using Histone Methyltransferase Inhibitors for the treatment of heart failure. Dr. Papait from Humanitas Clinical and Research Center in Italy and colleagues focused on G9A, a histone methyltransferase that defines a repressive epigenetic signature. Using normal and stressed cardiomyocytes from a conditional cardiac specific G9A knockout mouse, and a specific G9A inhibitor, they showed that the histone methyltransferase G9A was important in defining the epigenetic landscape that maintained the transcription program of the cardiomyocyte. It was also important for the regulation of gene expression reprogramming during cardiac hypertrophy.
Furthermore, impaired G9A function promoted cardiac dysfunction. Thus, these findings suggest that G9A may represent a therapeutic target for early stages of cardiac hypertrophy.
That wraps it up for your summaries, now for our feature discussion.
For today's feature discussion, we're talking about the very important topic of the prognosis of prehypertension without progression to hypertension. Now, we've always known that mild blood pressure elevations that we call prehypertension are associated with cardiovascular risk. However, this risk could be attributable to the fact that these patients with prehypertension eventually progress to overt hypertension. But, what happens to the patients with prehypertension who do not progress to hypertension, and what is the role of early versus late onset prehypertension?
Well, we have some answers today and I am so pleased to have the first and corresponding author with us, Dr. Teemu Niiranen, from Boston University's Framingham Heart Study. Welcome, Teemu.
Dr. Teemu Niiranen: Thank you very much, great to be here.
Dr. Carolyn Lam: And to help us along in this discussion, we have a familiar voice. Dr. Wanpen Vongpatanasin, associate editor from UT Southwestern. Welcome back, Wanpen.
Dr. Wanpen Vongpatanasin: Thank you Carolyn. Happy to be here.
Dr. Carolyn Lam: Teemu, you know, I sort of set the background that you so nicely articulated in this research letter, but could you tell us a little bit more of what you were looking at, how you did it, and what you found?
Dr. Teemu Niiranaen: My boss, Dr. Vasan, was also a coauthor in this paper, he already showed some 15 years ago that prehypertension carries greater cardiovascular risk than perfectly normal blood pressure. However, it's pretty much unclear what happens to people who are prehypertension but never go on to develop hypertension because even the name suggests that if you have prehypertension you will get hypertension. We also looked at what effect does the age of developing prehypertension and hypertension have in this context.
We used a case cohort setting in the Framingham Heart Study in the way that we only looked at 5 1/2 thousand decedents. These were people who had already passed away. Then we categorized those decedents into 5 categories, people who never got prehypertension or hypertension, people who developed prehypertension late in life, who never developed hypertension, and people who developed early onset prehypertension but never developed hypertension, and then people who went on to develop late or early onset hypertension. We used a cutoff of 55 years as the definition of early onset versus late onset.
Then, in a case cohort setting, we estimated case versus controls, adjusted case versus control odds ratios, for the 4 prehypertension/hypertension categories versus those who died without ever developing prehypertension.
Dr. Carolyn Lam: Teemu, could I just stop you here before you share the intriguing results. I just wanted to remark that it's so amazing how the Framingham Heart Study really enables analysis like this, simply because of the long follow up and just the great detail and the standardization of blood pressure measurements and so on. I mean, as I said, I worked at the Framingham Heart Center, and we were trained to do this in a standardized fashion.
Define prehypertension and hypertension, just in case, and then please tell us your results.
Dr. Teemu Niiranaen: Prehypertension was 120 to 135 systolic blood pressure, and a diastolic blood pressure of 80 to 89 millimeters mercury, and then hypertension was 140 over 90 millimeters mercury, or antihypertensive medication, and yes, your correct that the Framingham Heart Study provides a very unique setting. Especially for defining early versus late onset hypertension because we can define the age of hypertension or prehypertension or prehypertension onset objectively because these people have been followed up, they have attended so many exams, especially the original cohorts.
But, to the results, so we observed that basically people who develop prehypertension, either early and especially late in life, but did not ever develop hypertension, their risk, or odds of dying of cardiovascular disease versus non-cardiovascular disease was pretty much similar to those who never develop prehypertension or hypertension, while conversely the people who went on to develop either late or especially early onset hypertension, or developed early onset hypertension they had considerably greater risk of cardiovascular death versus those who developed either prehypertension or hypertension. That's our main result. I won't go into conclusions yet.
Dr. Carolyn Lam: Okay, but maybe at this point, I could ask Wanpen to share some thoughts. I mean, this is very striking findings. Curious what you think the clinical implications were, and especially as we discussed among the editors.
Dr. Wanpen Vongpatanasin: It is very important study that, as Teemu outlined it, to look at the fate of people with prehypertension and I think that's the first time we had this kind of data to show whether the earlier versus late prehypertension and even hypertension itself. I don't think people have looked at in the large number in terms of outcome people who have early versus late onset hypertension. I found the result to be fascinating.
Dr. Carolyn Lam: Yeah, what does this mean though when we see a patient with this sort of borderline hypertension, you know, falling in the prehypertension range. We don't know whether they're going to develop hypertension. What do you think the clinical implications are? Teemu?
Dr. Teemu Niiranaen: Unfortunately a lot of the people who develop prehypertension as the name suggests they go on to develop hypertension, but there is still a considerably great part that never develop hypertension, and our study shows basically that if you are able as a doctor or a patient to prevent progression to hypertension you are much better off and this really hasn't been previously shown, so it just should motivate patients and also doctors to strive to, if they see a prehypertensive individual, try to through lifestyle and other interventions try to prevent the progression to hypertension.
Dr. Carolyn Lam: Yeah, I think that was one of the take home messages for sure. Were there any other plans for future work you think that needs to be done?
Dr. Teemu Niiranaen: There's the everlasting problem with observational studies, so definitely it would be great if our results could be taken into clinical trials or anything to test whether interventions, A, that preventing the progression from prehypertension to hypertension could then impact cardiovascular outcomes.
Dr. Carolyn Lam: Indeed, and if I may comment, I've always wondered about ethnic differences when it comes to this. The one thing that Framingham, you know, it's difficult to see from there, is what happens in other ethnicities other than white ethnicities, isn't it? Still, very striking findings. Wanpen did you have any other comments or questions from Teemu?
Dr. Wanpen Vongpatanasin: Well, I think that one thing also that's interesting to me is even the people who had early onset prehypertension, although the number of CHD deaths were not significant, but the odds still 28 percent higher than the control that will never have prehypertension so, I think that that the signal is there but perhaps because the number of people who had prehypertension but never really progress to prehypertension is relatively small. It could be underpowered to see the significance and I think that from this study, it tells me that the exposure to blood pressure to our life, I think is the blood pressure lowered on the cardiovascular system, I think that's the one that really determine the cardiovascular outcome the most. I think that we should not discount that this is not a truly benign phenomenon, I think hopefully they'll be some more data from the Framingham group or other group.
Also, I think that this study also very important to show that early onset hypertension actually have the worst prognosis, and often time when people come to see a doctor when they're 30 and 40 years old, they don't really want to take medicine, and the physician often time are reluctant to prescribe the drug, and I think that this study say that we probably need to be a little bit more serious about it, because they actually have the most cardiovascular events.
Dr. Carolyn Lam: What excellent points, and you know what? At this point I just want to highlight that beautiful figure that you have in your research letter, Teemu. I think it says it all. It highlights that point estimate for the prehypertension groups is not exactly 1. If anything, it is above 1, right? For the odds of poor outcomes, so I do take Wanpen's point as well. Beautiful figures, and I also actually want to use that to ask you a different question Teemu. You have 1 figure, because this is a research letter that only allows 1 figure and 800 words, and you've put so much important information into that space. I'd love for you to share that experience with our listeners too, of a research letter versus a full paper. Why did you choose to submit yours as a research letter, and how was that?
Dr. Teemu Niiranaen: One of the important take home messages from this was the differences between early onset versus late onset hypertension that we'd been also recently publishing on, so we wanted to delve more in depth on this prognosis of prehypertension versus hypertension so we don't have to be repetitive too much. We decided to focus on this very small topic most intensively, therefore we decided that maybe a research letter would be the most effective way so we could communicate all the really novel stuff that we have in just one figure. Well, it has 3 panels, but it still counts as 1 figure.
I just wanted to point out that maybe the early onset prehypertension, yeah the confidence intervals are somewhat wide, but the panels sees for coronary heart disease versus non-cardiovascular disease deaths, so that's maybe a bit more underpowered than the back panel B, so the CHD deaths are part of the CBD deaths, so with CBD deaths, the early onset prehypertension, the odds ration was 1.09, but still of course the confidence intervals reach up to 1.49. Just to clarify the difference between panel B and panel C, so B's better powered.
Dr. Carolyn Lam: It's a very nice figure, and indeed, I think it works very, very well as a research letter, and I think the fact that we're discussing it right now shows that length doesn't dictate importance. Wanpen you had a few comments about that. What do you think of a research letter format?
Dr. Wanpen Vongpatanasin: Yes, I think this research letter is a really important part of articles in Circulation. I think that all the others should be aware that we're trying to enter at submission if it's suitable, just like this one. It actually show up in the pub med exactly like the full article and gets cited as much and sometimes much more than a regular article because it capture the essence of one more focused problem and the figures and table allow to show only one or two at a time, so they really capture the essence or the guts of the article and the reader can go through that quickly and grasp the concept and learn within flipping through a few pages.
I think we should have many more interesting research letter like this.
Dr. Carolyn Lam: Congratulations again Teemu for a beautiful paper, a very important one. Thank you Wanpen for shepherding this one.
And thank you listeners for joining us today. Don't forget to tune in again next week.