Feb 27, 2018
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.