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Circulation on the Run

Sep 18, 2017

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 we will be discussing the cost effectiveness of statin use guidelines for the prime and prevention of coronary heart disease and stroke. Comparing the 2013 American College of Cardiology American Heart Association guidelines with the adult treatment panel three guidelines. A very important and current discussion that you don't want to miss. All coming up right after these summaries.

                                The first original paper in this week's journal is the largest study yet reported that assessed the long term outcome of Takayasu's Arthritis. First author, Dr. Comarmond, and corresponding author Dr. Saadoun and colleagues from Hospital Pitie-Salpetriere in Paris performed a retrospective, multi-centered study of 318 patients from the French Takayasu network including patients with Takayasu Arthritis fulfilling the American college of Rheumatology and/or Ishikawa criteria. They found that, firstly, 50% of  Takayasu arthritis patients relapse and experienced a vascular complication at ten years. Secondly, male sex, elevated CRP, and carotidynia were independently associated with relapse and with a two-fold higher risk of relapse. And thirdly, patients at high risk for vascular complications could be identified according to presence of two or more of the following risk factors: progressive clinical course diagnosis, thoracic aortic involvement, and or retinopathy. In summary, these factors identify patients with a high risk of relapse or vascular complications and may therefore serve to adjust more aggressive management and close follow up in Takayasu's Arthritis.

                                The next study provides experimental evidence for a pathogenic role of the transcription factor interferon regulatory factor five or IRF-5 in atherosclerosis. In this study from co-first authors, Dr. Seneviratne and Dr. Edsfeldt, corresponding author Dr. Monoco from Kennedy Institute of Rheumatology in Oxford, United Kingdom, and colleagues. The authors showed that atherosclerosis prone apple-E negative mice who were also deficient in IRF-5 showed reduced atherosclerosis lesions and necrotic core formation. They found that the development of the lesion necrotic core was controlled by IRF-5 through impairment of macrophage dead cell removal, or spherocytosis. They further demonstrated that the CD-11C gene was a direct target of IRF-5 in macrophages and that IRF-5 was important in maintaining CD-11C positive macrophages in atherosclerotic lesions. In summary IRF-5 was shown to be a potential therapeutic target since its inhibition could reduce plaque inflammation and necrotic core size, thus potentially promoting a stable plaque phenotype with a lower risk of acute clinical complications.

                                The next study is the first to assemble a transcriptomic framework of multiple cardiac cell populations during post natal development and following injury, thus enabling comparative analysis of the regenerative or new natal state, compared to the non regenerative or adult state. In this study from first author Dr. Quaife-Ryan and co- corresponding authors Dr. Porrello from the Royal Children's Hospital and Dr. Hudson from the University of Queensland, Australia. The authors isolated cardiomyocytes, fibroblasts, leukocytes and endothelial cells from infarct and non infarct neonatal and adult mouse hearts. The then performed RNA sequencing on these cell populations to generate the transcriptome of the major cardiac cell populations during cardiac development, repair and regeneration. They further, surveyed the epigenetic landscape of cardiomyocytes during post natal maturation by performing deep sequencing of assessable chromatin regions. This comprehensive profiling of cardiomyocytes and non myocyte transcriptional programs uncovered several injury responsive genes across regenerative and non regenerative time points. The majority of transcriptional changes in all cardiac cell types resulted from development maturation from neo natal stages to adulthood. Rather that activation of a distinct regeneration specific gene program. Furthermore, adult leukocytes and fibroblasts were characterized by the expression of a proliferative gene expression network following infarction, which mirrored the neonatal state.

                                But in contrast cardiomyocytes failed to reactive the neonatal proliferative network following infarction which was associated with loss of chromatin accessibility around cell cycle genes during post natal maturation. In summary these findings are significant because they defined a regulatory program underpinning the neonatal regenerative state and identified chromatin modifications in adult myocytes that could restrict cardiac regenerative potential after birth and may need to be overcome to facilitate cell cycle re entry in adults.

                                The final study reports results of two studies investigating the pharmicokinetic and clinical outcomes of a new drug coated balloon to treat femoral popliteal disease. The first study is the Illuminate pivotal study in which 300 symptomatic patients were randomized to stellarex drug coated balloon or standard angioplasty. The primary safety outcome was freedom from device and procedure related death through 30 days and freedom from target limb major amputation and clinically driven target lesion revascularization through 12 months. The primary effectiveness endpoint was primary patency through 12 months. The second study was the illuminate pharmicokinetic study in which paclitaxel plasma concentrations were measured after last balloon deployment and at pre specified times until no longer detectable. In this report my first in corresponding Dr. Krishnan from Mount Sinai Medical Center in New York. In the pivotal study the primary safety endpoint and the primary patency rate was significantly higher with the drug coated balloon. The rate of clinically driven target lesion revascularization was significantly lower in the drug coated balloon cohort. pharmicokinetic outcomes showed that all patients had detectable Placitexal levels after drug coated balloon deployment that declined within the first hour.

                                In summary these findings demonstrate the safety profile and superior patency of the stellarex drug coated balloon for femoral popliteal disease compared to standard angioplasty. This therefore suggests that this drug coated balloon may be a valuable treatment option for patients with superficial femoral and popliteal artery disease.

                                Well those were your summaries now for our feature discussion.

                                Today we are discussing the highly relevant and also highly controversial issue of Statins for primary prevention of cardiovascular disease and when do we start a statin. How cost effective is it, and of course all this discussion really began with the 2013 ACC/AHA guidelines that expanded the recommended statin use. I am so pleased because this week’s journal actually provides, for the first time, some cost effectiveness data that may help us in making this decision and in facing our patients. I can't tell you the number of times I've had an individual patient come to me and just want to discuss all the pros and cons of starting a statin for primary prevention and I'm sure, listeners out there you identify with this. Well hang because today we have the corresponding author of today's feature paper Dr. Kirsten Bibbins-Domingo from University of California, San Francisco  as well as the editorial list on this wonderful paper, Dr. Rodney Hayward from University of Michigan and VA Ann Arbor. Welcome Kirsten and Rod.

Dr. Kirsten Bibbins:          Thank you.

Dr. Rodney Hayward:     Great to be here.

Dr. Carolyn Lam:               Kirsten, could you please tell us the top line results of what you found in this paper, it's such an important paper.

Dr. Kirsten Bibbins:          We use simulation modeling to compare three approaches to giving Statins for primary prevention. The older guideline in the US called ATP-3, the one that you mentioned in your introduction the ACC/AHA guideline that broadened the use of Statins to many many more people and then an even broader strategy where we don't look at cardiovascular risk, and in each of these approaches we found that the use of Statins for primary prevention was very effective and in fact cost saving, when we did a cost effectiveness analysis. And regardless of the assumptions that we made about more side effects then we had known from the literature or could anticipate or regardless of the parameters that we put into the model we found that, pretty much that the broad use of these medications is effective and, in fact, cost saving.

Dr. Carolyn Lam:               Could you give us an idea of what you used in that simulation model, what population was it, how applicable is it to people outside the US, for example.

Dr. Kirsten Bibbins:          Simulation modeling is a way to take the evidence that we have from multiple types of studies and to try to synthesize that evidence and apply it to, in this case, the population of the US. So our simulation model uses the demographics of the US and takes the primary studies and the effect rises that we know from those studies and using that model we found that each of these three approaches had both health benefits and cost saving benefits. It's applicability might be somewhat variable if this were applied to a different population, but the effects are pretty substantial and so it suggests that Statins are likely to be beneficial using these approaches in a broad array of populations.

Dr. Carolyn Lam:               Could you give us an idea of the estimated effect size, you know, when you say cost effective, for example, how, how much and for what. Give us everyday clinician some kind of take home of numbers that would make sense for them.

Dr. Kirsten Bibbins:          One way to think about these types of cost effectiveness analysis is that often times they give us numbers that suggest that we have to pay a certain amount to get the type of health benefit that we want. In this case because we found that they were cost savings, it actually suggests that the amount that we pay for Statins, to give Statins to a broad population of individuals actually saves us money. It saves us money in terms of the heart attacks that are avoided, and the other types of health care costs that are avoided and probably a number that might be relevant to your audience might be that the number that one would need to treat in order get one additional year of life, through using these Statins for primary prevention, is on the order of about 35 individuals and so that's a small number that we would be treating in a primary care practice in order for an additional quality adjusted year of life.

Dr. Carolyn Lam:               I thought that was really one of the most remarkable figures, you know, that the ATP-3 guidelines would result in 8.8 million more statin users than the status quo and that was an entity of 35 per quality of life. Was that correct?

Dr. Kirsten Bibbns:           That's exactly right.

Dr. Carolyn Lam:               Whereas the ACC/AHA guidelines could potentially result up to 12.3 million more statin users than the ATP-3 guidelines with a marginal number needed of 68 per quality of life. So very, very useful figures, but you know, I began by saying my individual patient. These feel like population bases statistics, you know, and my individual patient kind of wants to know but for me, what's a long term risk and so on. And these are issues that you have discussed so elegantly, Rod, in your editorial. Could you enlighten us a bit on these considerations.

Dr. Rodney Hayward:     Sometimes decisions that we have to make in policy are inherently population based decisions, like putting fluoride in the water, in which the average benefit of cost for population is what you have. Cause you can't treat individual separately with that type of intervention, but with a statin, the average that a population gets is not the important thing to our patients across the room. And it's sort of the number needed to treat for them, how likely are they to benefit. And what I think this paper establishes very well, and I think it's important to start with why the areas of agreement here, this establishes that the new guidelines are a great idea. There's no assumptions in this model that would change that starting people on a statin between 7.5 and 10 % ten year risk isn't a good idea. And that aspect of the paper even some of the issues I have about some of the assumptions are not going to be relevant, where it starts to become concerning, and will always be controversial is how low of risk to start it at. Do we go from 7.5 to a 5% risk? Do we start putting everyone at age forty on a statin?

                                And at that case, certain elements of this simulation model are very important, the likelihood of an individual benefiting becomes very, very small. And even a small dislike of the medicine, would outweigh that. But also you have to assume in this model that we know all the bad things of a statin at 20-25 years, because you're starting to put people on a daily medicine that's biologically active for 30 years. And it's impossible statistically, epidemiologically, to know with any degree of certainty whether or not being on these medicines for 20-30 years would have unheard effects. We don't have that ability, currently, even if we had the databases so how should individuals think about that, well my feeling is that is part of the shared decision making of how much a patient worries about unknowns, about being on a medicine long-term versus they worry more about the potential for a heart attack prevention which are likely there. I want to emphasize again these are not relevant concerns when we're talking about the current guidelines, these are only concerns when we start pushing it down to a 5% risk or everyone over 40 where you're extending to tens of millions more people, in which the population benefits would be substantial.

                                As long as people don't mind taking a pill every day at those ages and we know all of the harms being on a statin for 20 years. And that's something that no one knows.

Dr. Carolyn Lam:               Rod that was just so eloquently stated, and listeners out there, you just have to read this editorial. It states these things very clearly, and I think it's really helpful in our thinking of what to tell patients when we do see them. Kirsten, I'd love to invite your thoughts on what Rod just said, you acknowledge this, fully in your paper. Curious, any steps you took to maybe address this and what you would say as a take home message for clinicians?

Dr. Kirsten Bibbins:          I think that Rod's bringing out exactly the point. And, I think, we have seen the shift from the earlier guideline to the most recent guideline in putting more people on Statins and these medications certainly have the benefit, but as you bring more and more people on who have lower overall cardiovascular risk, their likelihood of benefiting while there, is always smaller. And so then other things do come in to play, and I think the thing that probably was most surprising to us as we put this work together, was how sensitive our results were to, essentially, a patients preference as we moved down into including more of these lower risk individuals. That means that an individual who's lower risk may not directly benefit or their likelihood of benefiting in terms of avoiding a heart attack is lower, and so therefore the facts that their tolerance for taking a daily medication is in fact, then becomes relevant in to their particular trade off for taking this medication. And I think that is clinically important as we think about including more and more lower risk people into these types preventative guidelines, the threshold for any given individuals tolerance for taking a daily medication and of course, as Rod said, if you're doing this over many years and decades the fact that we don't actually know what will happen over the long term, also becomes relevant.

Dr. Carolyn Lam:               Just maybe one last question for both of you. What do you think our next step is here, what more do we need?

Dr. Kirsten Bibbins:          I just think we still want to continue to expand our understanding of what the long term effects and side effects of daily use of statin therapies are, again I'd want to emphasize as you said it's always important to understand patients preference, but, as Rod said, our current guidelines which really have focused on higher risk individuals, I wouldn't want it to be lost that these medications are in fact very effective and so I think having an understanding of the long term use of these medications and what the potential side effects when used over a long period time are, I think that's a critically important area. As well as really developing continuing to develop the tools that can help doctors and patients together engage in the conversation about the trade off for given individual.

Dr. Rodney Hayward:     I would definitely agree with that, but I would focus on three bits of science. That are critically important for refining this issue. The one is something we currently don't have and that's post marketing surveillance of medicines long term. That when you look at the data we have, that, most of them follow patients either a short period of time and don't have enough continuity or their smaller studies in which outcomes that are long term might be found. And this is a place where big data, but also combining and sharing data across health systems could really help us monitor. This is not just an issue for Statins but as more medicines are recommended for younger individuals with life expectancy we need to work on that. Two the results are insensitive meaning that it always looks good, for people in the current guidelines but two elements of the model for people at a 5% risk or starting people at age 40 are assumptions that are being made with the best available data now, but have some considerable concerns and could be improved.

                                One is, we don't know the impact of a non fatal heart attack on future outcomes, my personal opinion is the assumption in this model, is probably an overestimate. Unimportant for the current guidelines but would be critically important for these younger risk people and ways to really understand the impact of non fatal events on future risk are epidemiologically tricky and it's very easy to pick up things that are markers that aren't causal and then when you run your models you think you're extending life years where you really aren't. And the other is we still don't know how much a Statins relative benefit varies by a persons LDL level, that might seem astounding but there's evidence on both sides. That it is related to baseline LDL and it's not. This is a completely solvable question, the CTT group has the data and we really need them to publish and tell us how much the relative risk of a statin varies by that. The current assumption in the ACC/AHA guidelines is that it is not correlated, the assumption in Kirsten's model is that it is.

                                Either could be correct, my personal opinion is it's probably in between, those two, but that would help us in terms of thinking of extending to the lower people. If LDL is a partial factor that probably should be considered, if it's not then only risks should be considered. That is completely answerable for those that have access to the RCT data and I'm hoping that this paper may encourage that publication.

Dr. Carolyn Lam:               Wow, those were such insightful comments, I can't thank you enough, Rod and Kirsten for joining us today.

                                Listeners I'm sure you enjoyed that and learned so much just like I did. Don't forget to join us again next week.