Apr 22, 2019
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.
Dr Greg Hundley: And I'm Greg Hundley, associate editor as well at Circulation, and director of the Poly Heart Center in Richmond, Virginia, at VCU Health. Well, I'm going to talk about anti-hyperglycemic agents and look at a very important meta-analysis.
Dr Carolyn Lam: Those are the rage: GLP-1 receptor agonists and SGLT-2 inhibitors. But first, let's talk about psychosocial stress and cardiovascular health. So what is the joint impact of multiple stressors on racial or ethnic disparities in cardiovascular health?
Well, this question was tackled by Dr Albert, from University of California San Francisco Center for the Study of Adversity and Cardiovascular Disease and her colleagues. They basically studied more than 25,000 women participating in the women's health study follow-up cohort, and examined the relationship between cumulative psychosocial stress and ideal cardiovascular health as defined by the American Heart Association Strategic 2020 Goals.
As a reminder, this health metric includes smoking, BMI, physical activity, diet, blood pressure, total cholesterol and glucose, and higher levels indicate more ideal cardiovascular health and less cardiovascular risk.
So, they found that both cumulative psychosocial stress and ideal cardiovascular health varied by race or ethnicity. Mean cumulative psychosocial stress scores were higher in Hispanic, Black, and Asian women compared to white women, even after adjusting for age, socioeconomic status and psychological status such as depression and anxiety. The mean ideal cardiovascular health scores remained worse in blacks and better in Asians compared to whites, despite taking into account socioeconomic factors and cumulative psychosocial stress.
Dr Greg Hundley: So Carolyn, how should clinicians incorporate this information in what we do every day?
Dr Carolyn Lam: Although the cumulative psychological stress and socioeconomic status did not fully explain the racial or ethnic differences in ideal cardiovascular health that we saw, clinicians should be informed by these data that psychosocial stressors are social determinants of health that have different prevalence according to race and ethnicity. I think that's what we need to learn. And of course these data support the need for additional work that addresses the joint impact of multiple social determinants of health on cardiovascular disease and in diverse populations.
Dr Greg Hundley: Very good, Carolyn. That was really an interesting article. Well, I'm going to switch gears and talk about the role of red blood cells in promoting vascular calcification. My article is from Dimitrios Tziakas from the Department of Cardiology in Thrace, Alexandropoulos, in Greece.
Now, the presence of extravasated erythrocytes in human atherosclerotic lesions was described several years ago, but little is known about a possible active role of red blood cells during these cardiovascular disease processes. Clinical studies suggest that intraplaque hemorrhage may be associated with the progression of coronary, carotid, and atherosclerotic lesions and degenerative calcific aortic valve stenosis. So, in the present study, the authors examined the contribution of erythrocytes to vascular and valvular lesion progression, focusing on the effects of red blood cells on the osteoblastic transdifferentiation of smooth muscle cells in calcification.
Dr Carolyn Lam: Interesting. So, what did they find?
Dr Greg Hundley: So, lysed erythrocytes, and in particular their membrane faction, enhanced human and murine arterial smooth muscle cell mineralization and vascular aortic ring calcification. Red blood cell membranes injected in the vascular regions of atherosclerotic-prone mice also promoted calcification and red blood cells were found to co-localize with osteoblast like cells in human atherosclerotic plaques, stenotic aortic valves, and abdominal aortic aneurysms. And so, the study demonstrated that intra plaque hemorrhage promotes atherosclerotic and valvular lesion calcification and membranes of extravasated lysed red blood cells appeared to play an important role in the process. The investigators also showed a mechanism, that nitric oxide derived from erythrocyte endothelial nitric oxides synthase is involved, at least in part, in mediating the effects of red blood cells on vascular calcification.
Dr Carolyn Lam: Thanks, Greg. Now back to another, well, clinical paper with the next one asking, do mid-life biomarkers of heart and kidney damage associate with the level of and decline in physical capability with aging? Dr Kuh and colleagues from MRC Unit of Lifelong Health and Aging at University College London used data on 1,736 men and women from the oldest British birth cohort study. And, looked at their walking speed, chair rise speed, balance time, and grip strength. Assessed at ages 60 to 64 and 69 years. They tested the associations between Cystatin C, NT-proBNP, interleukin-6, and E-selectin all at ages 60 to 64 years with their performance at 69 years. And what they found was the lower levels of NT-proBNP in interleukin-6 in middle aged adults were independently associated with better physical capability up to nine years later. And all these associations were stronger than those observed for conventional risk factors: including lipids, blood pressure, and glycemia, and were not explained by the onset of cardio vascular and kidney disease or diabetes.
Dr Greg Hundley: Carolyn, is this saying we should now measure these biomarkers in mid-life?
Dr Carolyn Lam: Ah, before considering the use of NT-proBNP and IL-6 or interleukin-6 for risk stratification, we really do need further research to untangle whether these associations exist because the biomarkers are an integrated measure of accumulated exposures to stressors. Or, whether they are really capturing early an organ damage. Or, whether they are marking additional risk pathways. So, this and more is discussed in a great accompanying editorial entitled "Putting the Measurement of Physical Capacity in Older Adults in its Place". And that's by Dr Kritchevsky from Wake Forest School of Medicine.
Dr Greg Hundley: That's a favorite of my heart, Caroline. The old institution Wake Forest. But, I'm going to switch now and tell you a little bit about plasma ceramides and this is an article from Wei Zhao from the Department of Epidemiology in Population Health at Albert Einstein College of Medicine in Bronx, New York. The study evaluates the role of ceramides and what are those? Well, they're a class of bio-active lipids composed of sphingosines and fatty acids. And are involved in the development of cardiovascular disease. Elevated circulating levels of ceramides have been shown to be associated with increased risk of cardiovascular events, cardiovascular death, and even so, after adjusting for other cardiovascular disease risk factors. Now, interestingly, ceramide metabolism has long been noted to be closely related to HIV infection. But, the relationship has not been fully understood. HIV infected cells may cause enhancement of sphingomyelin volume breakdown and accumulation of intercellular ceramides, whereas intercellular accumulation is associated with enhanced replication of HIV.
So, what did this study do? They evaluated circulating levels of four ceramides species which have been investigated in previous studies of non-HIV populations. And were measured in 737 women and men, 520 HIV infected and 217 HIV uninfected from the Women's Intra-Agency HIV Study and the Multi-Center Aids Cohort Study. And they compared the relationships with the progression of carotid artery disease assessed by B-mode ultrasound over a seven year period.
Dr Carolyn Lam: Interesting approach. So, what did they find?
Dr Greg Hundley: Elevated ceramide levels were associated with anti-retroviral therapy use. Particularly, protease inhibitor use HIV infected individuals. All four ceramides were highly correlated with each other and significantly correlated with total cholesterol and LDL cholesterol. And of note, remember they were measuring four, but C16:0 and C24:1 ceramides rather that C22:0 and C24:0 ceramides were more closely correlated with specific modified activation and inflammation markers and, surface markers of CD4 t-cell activation. Elevated plasma levels of C16:0 and C24:1 ceramides were also associated with progression of carotid artery atherosclerosis. So, in summary, the results of this study provide new information on biological mechanisms that may involve the specific mono-site activation and inflammation beyond cardiovascular disease traditional risk factors like cholesterol levels. For the association between ceramides and CVD, particularly among individuals living with HIV infection.
Dr Carolyn Lam: Fascinating. Thanks, Greg. Now that sets us up for beautifully for our featured discussion.
Dr Greg Hundley: Welcome everyone, to our podcast. My name is Greg Hundley and we've got a very exciting paper for the second part of our program today. With us we have Dr Thomas Zelniker from Brigham and Women's Hospital. And then, also, a guest editor, Dr John McMurray from Glasgow, Scotland. We're going to be discussing a meta-analysis in type 2 diabetic patients. Thomas, can you tell us a little bit about the study population, your design, and what where the outcomes that you saw in this study.
Dr Thomas Zelniker: As you know, the last half decade, members of two drug classes, GLP1 receptor agonists and SGLT2 inhibitors, so our goal was to provide clear context by comparing or contrasting the benefit of these two drug classes, and in particular to investigate the potential heterogeneity in the treatment site between patients with and without atherosclerotic cardiovascular disease. For that reason, we performed meta-analysis of all randomized partially controlled cardiovascular outcome trials of GLP-1 receptor antagonists and SGLT-2 inhibitors. We included data from more than 77,000 patients, nearly 43,000 patients coming from the five GLP-1 receptor antagonist trials and approximately 34,000 patients coming from the three SGLT-2 inhibitor trials. We tried to compare patients with those with known established atherosclerotic cardiovascular disease with those that have multiple risk factors for but no evident ASCVD. And as you can see, our interests included MACE, or major atherosclerotic cardiovascular events, and its individual components, MI, stroke and cardiovascular death. And then we looked at hospitalization for heart failure and progression of kidney disease. The progression of kidney disease was defined as one of the broad composites consisting of new onset of macroalbuminuria, worsening of eGFR, end-stage kidney disease, or death due to renal cause. And then we also had a more narrow kidney outcome which excluded macroalbuminuria.
Dr Greg Hundley: Thomas, did you observe differences in the types of events between the two agents, as they would have impacted hospitalization for heart failure or the progression of renal disease?
Dr Thomas Zelniker: Right. So foremost both trial analyses reduced the risk of MACE, major atherosclerotic events, but the reduction of MACE was actually confined to those patients with atherosclerotic cardiovascular disease. We saw a 40% reduction in patients with known ASCVD, where neither of these groups reduced the risk of MACE in patients with only multiple risk factors but without ASCVD. Now, in terms of the individual components of MACE, both trial analyses reduced the risk of myocardial infarction cardiovascular death but only GLP-1 receptor agonist reduced the risk of stroke. In contrast, as SGLT-2 inhibitors vastly reduced the risk of hospitalization with heart failure by more than 30%, where there was only a non-significant 7% relative risk reduction with GLP-1 receptor antagonist.
GLP-1 receptor antagonists also reduced the broad kidney composite outcome. However, this effect was mainly driven by reduction macroalbuminuria. When excluding macroalbuminuria we found a non-significant relative risk reduction by 8% and this stands in contrast to a very robust relative risk reduction with SGLT-2 inhibitors of more than 45%.
Dr Greg Hundley: Thomas, you mentioned there was a difference in benefit for those with existing cardiovascular disease versus no-known cardiovascular disease upfront. What do you think the reason for that might be, and then did you have the same number of patients in the non-cardiovascular disease group? Did you have enough events in that group? And finally, do you think we might need to follow that patient population a little bit longer in time, to see those events as they didn't have pre-existing cardiovascular disease?
Dr Thomas Zelniker: These are fantastic points. I personally think it's biologically plausible that both drugs and receptors have the same benefit in both patient population to treatment effect may just require more time to become evident in patients with lower risk. You also mentioned a very good point, we had substantially more events in the patient cohort with ASCVD.
Dr Greg Hundley: Very good. So John, we want to turn to you now. Can you help us put those results of this study in perspective? Can you put this into context for us with other published reports using these particular ages?
Dr John McMurray: Certainly Greg, and I'd like to congratulate Thomas on what very important and very timely meta-analysis because, of course, what Thomas and his colleagues have done Greg, is to put all these studies together, to give us what meta-analysis does, which is much more power to look, for example, at components of composite outcomes, and we will in that way compare and contrast the differences and similarities between these two treatments. And as Thomas has mentioned, so interesting differences stand out but there are also some similarities that perhaps were not clear from the individual trials and I suppose the one that would perhaps stand out to me and might not have been realized by many of our readers, is myocardial infarction, that seems to be reduced to pretty much a similar extent by both GLP1 receptor antagonists and SGLT-2 inhibitors.
I think there had perhaps been a view out there from the individual trials, that maybe GLP-1 receptor antagonists have more effect on atherosclerotic events and SGLT-2 inhibitors more effect on heart failure and renal events and to some extent that's true, both agents seem to reduce myocardial infarction to approximately the same extent. Which in itself is interesting, perhaps raises some mechanistic questions. I mean, the differences that stood out is stroke is reduced by GLP-1 receptor antagonists but not by SGLT-2 inhibitors and conversely heart failure which is the opposite, which is by SGLT-2 inhibitors, but not by GLP-1 receptor antagonists in this meta-analysis.
So, I suppose, in summary what this tells us is that these drugs have complementary, perhaps additive cardiovascular benefits. Together, they potentially reduce the whole spectrum of the adverse cardiovascular events that occur in our patients with Type 2 diabetes, especially those who've got established cardiovascular disease.
Dr Greg Hundley: And so, just a last question here, for both Thomas and John, if you're considering in your practice, you have a diabetic patient that's not on these, one of these agents, and they have existing cardiovascular disease, how do you go about considering the addition or the switch to this type of medicine, and what practices do you use to effect that change?
Dr Thomas Zelniker: I guess, looking at patients, so we know that both drug classes have great benefits from MACE, right, but to people on antagonists having also reductions in stroke. So probably the associated risk is in the focus, I would probably rather go with the GLP-1 receptor antagonist. While looking at it from the heart failure perspective, or from the renal perspective, we see obviously bigger advantages attributed to inhibitors.
Dr Greg Hundley: And John, how about you?
Dr John McMurray: I would agree with Thomas' perspective, although I might add just a little caveat which is, of course, that the prevention of heart failure which is what, I think, the clear benefit of SGLT-2 inhibitors is, prevention of heart failure is different to the treatment of heart failure. So, patients at risk of heart failure sadly, an SGLT-2 inhibitor would make sense, but when it comes to patients with established heart failure event, of course we will get that answer because one of the great things about this recent incredible development of new therapies for diabetes, is that now there are now more studies underway including remarkable five trials in patients with different heart failure phenotypes, patients hospitalized, patients in the community, so we will learn a lot more about the use of these drugs, in particular cardiovascular populations.
Dr Greg Hundley: Excellent. I want to thank both Thomas Zelniker from Brigham and Women's Hospital and John McMurray, guest editor from Glasgow, Scotland for helping us work through this just fantastic meta-analysis study pointing us in a new direction for utilizing medications to treat diabetes and those that we see every day, with cardiovascular disease.
On behalf of Carolyn and myself, have a great week and we look forward to seeing you, next week.
Dr Carolyn Lam: This program is copyright American Heart Association, 2019.