Aug 19, 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 Gregory Hundley: And I'm Greg Hundley, associate editor from the Pauley Heart Center at VCU Health in Richmond, Virginia.
Well, Carolyn, this week's feature is from Professor Carl Lindstrom from Helsinki University Hospital and the University of Helsinki and evaluates whether administration of simvastatin via nasogastric tube in brain-dead individuals prior to cardiac transplant donation improves transplant recipient cardiac-related outcomes. It is a randomized trial using an inexpensive therapy, and I look forward to that discussion with Professor Lindstrom. How about we grab a cup of coffee and start off our discussion today.
Dr Carolyn Lam: All right, so here goes. The first paper that I want to discuss really looks at the question, is DNA methylation related to incident coronary heart disease? Well, Dr Agha from Columbia University in New York and colleagues looked at this and profiled epigenome-wide blood leukocyte DNA methylation in 11,461 individuals from nine population-based cohorts in the United States and Europe using the Illumina Infinium 450K microarray and prospectively ascertained coronary heart disease events.
Dr Gregory Hundley: So Carolyn, what did they find?
Dr Carolyn Lam: Well, they found that differences in blood leukocyte DNA methylation at 52 cytosine phosphate guanine sites were associated with incident coronary heart disease or myocardial infarction with a false discovery rate of less than 0.05. Several of the differentially methylated loci mapped to genes related to calcium regulation and kidney function. Exploratory analyses with Mendelian randomization supported a causal effect of DNA methylation on incident coronary heart disease at loci in active regulatory regions with links to noncoding, RNAs and genes involved in cellular and tissue structural components.
Very nice Caroline. So what's the summary for us clinically?
Dr Gregory Hundley: So, these findings really provide the first evidence that genomic regulation via epigenetic modifications in kidney function and calcium homeostasis related pathways may be involved in the development of coronary heart disease. The findings of epigenetic, loci related non-coding RNAs highlight pathways that have not immersed in genome-wide studies of coronary heart disease and therefore represent novel therapeutic targets, which thus far have not been explored.
Dr Carolyn Lam: Very good, Caroline. Well, I've got a basic paper that I want to present and it's from professor Xander Wehrens from the Baylor College of Medicine. And this study addresses factors that promote atrial fibrillation. The investigators found that reduced levels of protein phosphatase-1 regulatory subunit R3A in human atria are causally linked to abnormal calcium handling and atrial fibrillation pathogenesis.
In the absence of protein phosphatase-1 regulatory subunit R3A reducing binding of PP1 catalytic subunit increases phosphorylation levels of the ryanodine receptor, R2 calcium release channel, and phospholamban. Complex zone, profiling, a technique that combines native gel electrophoresis with mass spectrometry to obtain the composition of multi protein assemblies revealed that PP1 R3A is part of a macro molecular protein complex containing the ryanodine calcium release channel and the circuit 2APLN calcium uptake transporter.
Dr Gregory Hundley: Wow. Complex zone profiling. That's so cool, but what does it all mean for us clinically, Greg?
Dr Carolyn Lam: Well reduced levels of PP1 regulatory subunit contribute to abnormal calcium release and re-uptake and atrial monocytes, thereby promoting atrial fibrillation pathogenesis. And thus normalizing levels of PP1R3A phosphatase sub unit may represent a novel therapeutic approach to manage atrial fibrillation.
Dr Gregory Hundley: That's so cool. I next have a preclinical paper which contributes really to the understanding of molecular basis of pathological myocardial remodeling in heart failure. And this is from co-corresponding authors, doctors, Jung, Liu, and Lin-Jung from Shanghai East Hospital Tongji University School of Medicine in China. And the paper really focused on Forkhead box transcription factor P1 or Foxp1 in endothelial cells.
Dr Carolyn Lam: So Foxp1 Carolyn, tell me a little bit more about that.
Dr Gregory Hundley: Is it good that you asked before I asked you. Forkhead box proteins P or Foxp are large modular transcription repressors that bind to DNA via their highly conserved Forkhead DNA binding domains. Fox p1 is highly expressed in vascular endothelial cells and it's essential for normal cardiac development.
So, these authors found significantly down regulated Fox P1 expression in cardiac endothelial cells during cardiac remodeling induced by to angiotensin 2. Endothelial cell Fox P1 loss of function resulted in cardiac dysfunction following angiotensin 2 infusion and in the transverse aortic constriction model with severe cardiac fibrosis and mild adaptive cardiac hypertrophy.
Whereas endothelial cell Foxp1 gain of function protected against pathological cardiac remodeling and improved cardiac dysfunction transforming growth factor beta 1 signals were identified as Foxp1 direct target genes in endothelial cells which mediated the pathological cardiac fibrosis through cardiac fibroblasts proliferation and myofibroblast formation and maladaptive cardiac hypertrophy through TGF beta 1 promoted endothelial one expression during pathological cardiac remodeling.
Dr Carolyn Lam: Wow. Carolyn, this was very sophisticated work. What do we take away from it clinically?
Dr Gregory Hundley: These data really identified endothelial Foxp1 mediated TGF beta 1 signal pathway involvement in the promotion of cardiac fibrosis and cardiac hypertrophy via TGF beta 1 induction of the endothelin one pathway. So targeted delivery of TGF beta 1 silencing RNA or small interfering RNA to inhibit endothelial cell specific TGF beta 1 for the improvement of pathological cardiac remodeling may actually represent a future novel therapeutic strategy in managing this maladaptive cardiac fibrosis and hypertrophy during progression of heart failure.
Dr Carolyn Lam: That was an excellent summary of a very technical but informative basic science paper. I'm going to shift gears a little bit and talk a little bit about a study relating to clopidogrel and aspirin from the point study.
This study comes from Claiborne Johnston at the Dell Medical School and University of Texas. And in patients with acute minor ischemic stroke or high risk transient ischemic attack enrolled in the point trial. The combination of clopidogrel and aspirin for 90 days reduced major ischemic events but increased major hemorrhage compared to aspirin alone. This current paper is a secondary analysis of Point and involves 4,881 subjects in which the investigators assess the time course for benefit and risk from the combination of clopidogrel and aspirin.
The primary efficacy outcome was a composite of ischemic stroke, myocardial infarction or ischemic vascular death, and the primary safety outcome was major hemorrhage. Risks and benefits were estimated for delayed times of treatment initiation using left truncated models.
Dr Gregory Hundley: So, what did the study show Greg?
Dr Carolyn Lam: Well through 90 days, the rate of major ischemic events was initially high, then decreased markedly while the rate of major hemorrhage remained low but stayed constant throughout the study. Using a model based approach the optimal change point for major ischemic events was 21 days with a hazard ratio of 0.65 for clopidogrel aspirin versus aspirin at a P value of 0.0015 compared to later at 22 to 90 days. Where that hazard ratio was 1.38 and the P value only 0.24.
And the models showed benefits of clopidogrel aspirin for treatment delayed as long as three days after symptom onset. So Carolyn, the authors conclude that the benefit of clopidogrel aspirin occurs predominantly within the first 21 days and outweighs the low but ongoing risk of major hemorrhage. When considered with the results of the CHANCE study, a similar trial treating with clopidogrel aspirin for 21 days and showing no increase in major hemorrhage. The combined results suggest limiting clopidogrel aspirin use to 21 days may maximize benefit and reduce risk after TIA or minor ischemic stroke. Very practical paper.
Dr Gregory Hundley: Indeed. Thanks Greg. That was nice.
Dr Carolyn Lam: You bet.
Dr Gregory Hundley: Welcome everyone to our podcast and we're very pleased today to have Dr Antti Nykänen from Helsinki University in Finland as well as an associate editor, Justin Ezekowitz from Edmonton, Canada to discuss a very interesting randomized clinical trial related to the administration of simvastatin in those that are donors for heart transplantation and looking at subsequent outcomes in the patients that received the transplants. Antti, we're very excited for you to bring this to circulation. This particular paper and I wonder if you might outline for us what were your hypotheses that you are trying to test and what was your overall study design.
Dr Antti Nykänen: These things are routinely admitted to heart transplant recipients starting one to two days after transplantation. As previous clinical studies show that recipient that treatment has beneficial long-term effects on mortality and cardiac allograft vasculopathy. So in this clinical study, we basically tried to answer the question whether having the statin effect on the board even earlier before the transplant procurement by giving statins to the organ donor, if that would protect the transplanted hearts.
And this question was based potential rapid vascular and cardioprotective effects of statin and when our previous experimental study showing that treating the organ donor with statins will decreases vascular profusion injury in a heart transplant model. So basically we went on the test donor simvastatin clinically and randomize brain dead heart transplant donors either to a control group or to receive a signal 80 milligram dose of simvastatin before organ procurement.
Dr Gregory Hundley: I'm imagining that you would administer the simvastatin through either an intravenous mechanism or perhaps an NG tube, something like that. Maybe tell us a little bit about how you accomplish this and then what were your study results?
Dr Antti Nykänen: So, the simvastatin was administered to the donor via a nasogastric tube so there is no intravenous simvastatin formulation available. It needs to be absorbed and then activated through the liver so that can form. So, what we did in our previous experimental study was that we included a few clinical human brain-dead donors and basically investigated whether by giving simvastatin through the nasogastric tube would be metabolized and if you could detect that in in the donor plasma.
And that was actually the case. So in a few hours we saw up-regulated levels of simvastatin and also the active form in the donor or so basically showing off that treatment in a clinical brain dead donor of situation would be feasible. So we went on to use that method, clinical study and basically our primary outcome was plasma levels of cardiac injury biomarkers after transplantation.
And interestingly by treating the donor with simvastatin decreased and recipients for troponin INT levels six hours after transplant's profusion. Therefore, it seems that organ donor’s statin treatment reduces biomarkers of myocardial injury after transplantation in a clinical setting.
Dr Gregory Hundley: And did you examine any other functional measures of these patients? For example, ejection fraction by echo or anything, or was it primarily a biomarker study? That's the first question. Second question. Do you have any other information on other organs that also may have been donated? Would the statin have impacted, for example, liver transplantation?
Dr Antti Nykänen: That's a good question. So we did follow up cardiac function and the routine and serial measurements with the echocardiographic and we did not find any changes in the left ventricle. It took some traction after transplantation.
We did however find the decrease in proBNP levels into recipients. And that was maybe then at one week after transplantation and then it's leveled out after that.
And then regarding the next question about other transplanted organs. So once he was in a multi organ donor situation, so the same donor could have donated kidneys or livers, lungs, pancreas. So we did a follow up of the close recipients also. And I can say that there was no adverse effects, no decline in the survival or primary function of the transplanted organs. And interestingly we did find in the liver recipient that if the recipient received the liver from a donor simvastatin treated the liver function tests were better at day seven post-transplant.
Dr Gregory Hundley: Very interesting. And then lastly, just another outcome related question. Sometimes I know these patients undergo assessments for rejection by biopsy. Any information that you can share with us on outcomes related to biopsies.
Dr Antti Nykänen: We took routine biopsies, myocardial biopsies from the recipients and we did not find any significant differences in the biopsy program rejections either at 30 days or one year after transplantation. We did also monitor, we checked some treatments, so during the first 30 days there was significant decrease in the amount of rejection treatments for hemodynamically rejects it about not for the first year.
Dr Carolyn Lam: Wow. Just fabulous results. Thank you so much Antti. So Justin, I wanted to turn the conversation over toward you. Tell us about post-transplant management of these patients and then how do you see these study results integrating into our current standards of care.
Dr Justin Ezekowitz: Thanks Greg and Dr Nykänen and thanks for also letting us look at your work, which is terrific and extremely hard to do from the translation of your original 2011 circulation publication in animals and moving forward into the current publication years later. And thinking forward into the next few years of how we translate this into practice so that the current management after transplantation obviously involve multiple anti-rejection medications and many activities around detecting rejection is one of the key ways in which patients are managed other than their hemodynamics and other things that happen early.
What I was interested in is the generation of the idea where the simvastatin will really affect the clinical outcomes on the recipient and thinking that into the practice environment is, it's a very simple intervention to think about that would be easily applicable in, I think, most hospitals that do transplantation as either the recipient or the donor.
And Dr Nykänen, when you think about translating this into practice over either Europe or in Finland, I don't sense that this is going to be very difficult. Statins are well tolerated. The cardiology and other communities are very familiar with using a statin. But do you anticipate any barriers to translating this into practice as I think the guidelines may pick this up as something of interest.
Dr Antti Nykänen: Yes, I think we can show that it's feasible and we did a result on the biomarkers, so indicating that the damage the heart undergoes during the transplantation was smaller after donor statin treatment, so it is feasible, it's very cheap and it generally has a good safety profile. The timeframe for the treatment also feeds into the window of creating a brain dead organ donor. So in that sense it would be applicable in a donor treatment situation.
Dr Justin Ezekowitz: Right. And so I think this is the key point is even though it's a smaller trial in terms of the cardiology thinks about its trials. This is an area that doesn't have a lot of clinical trials were randomized clinical trials and so any evidence of benefit with a known, generally considered safe medication such as a statin, you would think that we should be able to broadly apply pretty quickly even on what are often not hard outcomes that are softer outcomes.
Because the benefit to risk ratio is generally favorable here. Dr Nykänen, my only other question to you is to think about the team getting this done must have been incredibly hard, but do you think there is a need for a larger trial to test this hypothesis on clinical outcomes or do you think this is really as far as you can go in the transplant world for an RCT.
Dr Antti Nykänen: So, it's been a long road from artery to single center clinical trial, which took time, so the patient numbers are fairly small in our study. We had 42 in the control group on 42 in the treatment group. I agree the risk benefit ratio is probably beneficial. But for sure it would be very nice to see larger studies that would look at the biomarker effects, but also would look at the other clinical end points.
Dr Justin Ezekowitz: Right, and that's a great point. It's only 84 patients, but a continued study of the area's important while perhaps implementation studies could go on to take what you found in both an animal translation into humans in a single center RCT and now translation into a larger population of recipients and their donors. I think that's probably the key next step in the transplantation world which has a tougher time getting larger number of patients into clinical trials for a variety of reasons.
So, congratulations to you and your team in getting this one to the point where we could probably apply this in a reasonable way with reasonable safety and an expected benefit to a broader group of patients.
Dr Gregory Hundley: Well this has been a fascinating discussion, Antti as well as Justin and what a relatively simple, clever idea that could have profound outcomes for this transplant population. We certainly want to thank you Antti for bringing this to circulation and sharing it with our readership. Are there any few last words you'd like to share with us before we close today?
Dr Antti Nykänen: Very nice to see how things evolve after this. We will for sure try to look more closely at the mechanisms and follow up the patient population for a long term follow up. And I hope this will stimulate some other experiments in the field.
Dr Gregory Hundley: Justin, any parting comments from the editorial team?
Dr Justin Ezekowitz: This is a great example of a full clinical trial that is mechanistic, but also has MR outcomes, and I just want to congratulate the authors on providing a very full picture of all the pieces that it takes to do in a clinical trial environment. Plus also collecting genetic and other biomarker material and imaging material. So, my compliments to the authors both to yourself, Dr Nykänen, but also the team that you assembled over the last six or eight years of doing this project, which we know was a huge task and my congratulations to you and your team.
Dr Gregory Hundley: We want to thank Dr Nykänen and his team from Finland and Justin Ezekowitz. We look forward to chatting with you next week.
Dr Carolyn Lam: This program is copyright American Heart Association, 2019