Circulation June 6, 2017 Issue

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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 paper today provides important trial evidence that will guide interventional management of symptomatic femoral artery disease, but first, here's your summary of this week's journal.

The first paper sheds light on the interaction between left ventricular dysfunction and mesenchymal stromal cell activation. First author, Dr. Naftali-Shani. Corresponding author, Dr. Leor and colleagues from Neufeld Cardiac Research Institute in Israel isolated mesenchymal stromal cells from cardiac and subcutaneous fat tissues of mice with left ventricular dysfunction, 28 days after myocardial infarction or sham operation. They further injected mesenchymal stromal cells or saline into the infracted myocardium of mice and evaluated left ventricular remodeling 28 days after myocardial infarction. They found that left ventricular dysfunction switched cardiac mesenchymal stromal cells towards an inflammatory phenotype and that these pro-inflammatory mesenchymal stromal cells contributed to adverse left ventricular remodeling and dysfunction. The inflammatory polarization of cardiac mesenchymal stromal cells by left ventricular dysfunction was mediated by toll-like receptor four. Finally, toll-like receptor four deficiency in mesenchymal stromal cells attenuated their pro-inflammatory activation, improved their reparative properties, graft survival, infarct repair and left ventricular remodeling.

In summary, the environment of the failing and infarcted myocardium drove resident and transplanted mesenchymal stromal cells towards a pro-inflammatory phenotype that restricted their survival and reparative effects in a mechanism mediated by toll-like receptor four. Targeting toll-like receptor four in mesenchymal stromal cells could improve the safety and efficacy of cell therapy in heart failure.

The next study provides evidence that fractional flow reserve or FFR is a useful index for decision-making in real life daily cath lab practice. First author, Dr. Ahn, corresponding author, Dr. Park and colleagues from Heart Institute Asan Medical Center in South Korea, evaluated the prognosis of deferred and revascularized coronary stenosis after FFR measurement in the IRIS-FFR registry of 5,848 prospectively enrolled patients. This large prospective registry showed that the FFR was linearly associated with the risk of cardiac events in deferred lesions. In addition, revascularization for coronary artery stenosis with a low FFR of less than 0.75 was associated with better outcomes than deferral, while for a stenosis with a high FFR of greater than 0.76, medical treatment would be a reasonable and safe strategy. Thus, the authors concluded that FFR may be considered a clinical prognostic index in addition to a physiological quantification for flow-limiting stenosis. These and other issues are discussed in an accompanying editorial by Doctors De Bruyne, Fournier and Barbato.

The next study sheds important insights into a potential disease modifier in pulmonary arterial hypertenstion, and that is vascular endothelial growth factor receptor three, or VEGF receptor three. First author, Dr. Hwangbo, Co-corresponding authors Dr. Chun and Dr. Jin from Yale Cardiovascular Research Center in Connecticut, used a combination of experimental animal models, human patient cells and detailed signaling studies to demonstrate the importance of a novel interaction between bone morphogenetic protein type two receptors, or BMPR2 and VEGF receptor three in regulating the robustness of endothelial bone morphogenic protein signaling response. They demonstrated that the interaction was critical for promoting BMPR2 internalization in response to bone morphogenic protein stimulation. They further showed that genetic deletion of endothelial VEGF receptor three in mice resulted in exacerbation of chronic hypoxia-induced pulmonary hypertension and impaired bone morphogenic protein signaling. Thus, these findings identify VEGF receptor three as a key regulator of endothelial BMPR2 signaling and a potential determinant of pulmonary arterial hypertension penetrance in humans.

The next study tells us that a low-dose drug-coated balloon may be a promising treatment option in symptomatic superficial femoral or popliteal artery disease. Dr. Schroeder and colleagues of the Jewish Hospital in Berlin, Germany, reported results of the ILLUMENATE European Randomized Clinical Trial, which was a prospective randomized multi-center, single-blinded trial, where patients were randomized 3:1 to treatment with a low-dose drug-coated balloon or an uncoated percutaneous transluminal angioplasty balloon. The primary safety endpoint was a composite of 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 at 12 months. The main results were that in symptomatic patients, with superficial femoral and/or proximal popliteal artery disease, low-dose, drug-coated balloon was safer and more effective than uncoated percutaneous transluminal angioplasty balloons through follow-up of 12 months. This is discussed as a novel strategy to reduce femoral popliteal restenosis in an accompanying editorial by Doctors Goldsweig and Aronow.

The final study provides important genotype-phenotype correlations of SCN5A mutations in probands with Brugada syndrome. First author, Dr. Yamagata, corresponding author, Dr. Shimizu and colleagues of Nippon Medical School in Tokyo, Japan, studied 415 Japanese Brugada syndrome probands to assess the association between SCN5A mutations and clinical outcomes. During a mean follow-up period of 72 months, the overall cardiac event rate was 2.5% per year. Compared to probands without mutations, probands with SCN5A mutations experienced their first cardiac event at a younger age, had a higher positive rate of late potentials and exhibited longer P-wave, PQ and QRS durations, and had a higher rate of cardiac events, especially when the mutations were located in the pore region of the encoded protein. The conclusion was therefore, that genetic screening for SCN5A mutations among Brugada syndrome probands may be useful for stratifying such patients according to their risk of subsequent cardiac events. Well, that wraps it up for your summaries. Now for our feature discussion.

Our feature paper today is the stuff that really could change guidelines. Now, we're talking about superficial femoral artery disease and its treatment. Unlike most other vascular beds, where stenting is the preferred modality of endovascular revascularization, the optimal therapy for superficial femoral artery disease remain controversial. However, today's paper really adds to our insight and I am so pleased to have the first and corresponding author Dr. Ilka Ott, from German Heart Center in Munich, as well as Dr. Manos Brilakis, Associate Editor, from UT Southwestern. Welcome both.

Dr. Ilka Ott: Welcome.

Dr. Manos Brilakis: Morning.

Dr. Carolyn Lam: Wonderful. So Ilka could you please share what you found?

Dr. Ilka Ott: We already know from previous studies there has been a lot of studies showing the drug-eluting balloon is superior to plain angioplasty in superficial artery disease. So then, in our study, we found that the treatment with the drug-eluting balloon plus stenting was very superior to the balloon angioplasty plus stenting and the directional atherectomy. The primary endpoint we used in the study was an angiographic endpoint. It was diameter of stenosis and this was significantly lower in the patients treated by drug-eluting balloon angioplasty, as compared to the balloon angioplasty and atherectomy group. Moreover, we had a clinical follow-up of 24 months and we found that also the target lesion revascularization was 70% in the group of drug-eluting balloon plus stent as compared to 37% in the balloon angioplasty and stent group, and 53% in the atherectomy group. We found a significant reduction also in the clinical endpoint of TLR at three years.

Dr. Carolyn Lam: Wow Ilka, congratulations, but may I just ask, was there any reason to think that a drug-eluting balloon would not be similarly beneficial as in other vascular beds?

Dr. Ilka Ott: Well, I think is not a novelty of the study. We already know from previous studies that drug-eluting balloon is superior to plain balloon angioplasty so that's not a surprising result. However, in disease of the femoral superficial artery we often have the problems, in particular when we treat complex lesions like along occlusions or along calcified stenosis, that drug-eluting balloon is not sufficient, so you need to also stabilize the lesion to stabilize dissections. You also need to do a stent implantation. Our study now shows that the combination of drug-eluting balloon plus stent is superior than plain balloon angioplasty plus stent. The nice approach is most of the time if you need a stent, if you use drug-eluting balloon and the lesion is stable and you don't need a stent you are glad. This has shown previous studies, however, if you need further treatment and you need to place a stent, we now show that the pretreatment with a drug-eluting balloon is a superior option than just the plain balloon angioplasty.

Dr. Carolyn Lam: Manos, what is your take on these results? Do you think it will impact guidelines?

Dr. Manos Brilakis: First of all, I would like to congratulate Dr. Ott for an excellent study. I think what is particularly important here, is the comparative effectiveness component. We have several studies circulating already about drug-coated balloons, have studies on stents, but we don't have studies addressing the other modalities like atherectomy. Why I was particularly impressed, is I think the study will have a finally an assessment of atherectomy as a primary strategy for calcified lesions and it's interesting that that was not as good efficacy. It was actually tents for worse TLR as compared to plain old balloon angioplasty and stent. Would like to ask Dr. Ott what is your kind thoughts about the alone atherectomy give the results of the study? Are they still doing it or is it falling out of favor?

Dr. Ilka Ott: Yes, I think this is a very important point. I think atherectomy alone is not an appropriate treatment but there are some data that atherectomy in combination with drug-eluting balloon gives much better results, or you may even think about a combination of atherectomy and drug-eluting stent, so it often is the case. This study also raises a lot of questions and gives some thought into further studies. I think in the combination atherectomy might still have its place.

Dr. Carolyn Lam: Could you tell us some of those plans for future studies?

Dr. Ilka Ott: Well, we are just in the initiation phase but I think one also very interesting concept is to compare drug-eluting balloon plus stent to the drug-eluting stents that have been on the market. However, as I said before, there's again the concept if you combine the drug-eluting balloon plus a stent it might be also, from the commercial aspect, better because sometimes you don't need the stent. And then moreover, the drug-eluting stents are much more expensive. It would be interested to see a study like that.

Dr. Carolyn Lam: What about the concern that the superficial femoral artery is subject to a lot of stretching and external compression and it's long and ... Maybe I'm out of date here about the concern of stent fractures and so on. It looks like your study has disproven this, or do you think the follow-up's long enough?

Dr. Ilka Ott: I think the follow-up of two years is quite good, but you're right, it seems like in the superficial femoral artery the restenosis process is much longer and more prolonged. Of course, you would like not to place a stent in the SSA but from the interventional aspect, it's often not possible because if you have a dissection with a limiting the flow, you have to fix that by putting in a stent. Nitinol stents are pretty good these days. Moreover, we have another generation of the woven stents the Supera stents that might also be an interesting point to investigate in comparison to the strategy we now have shown to be superior.

Dr. Manos Brilakis: I think what we need is more studies like this, that they take the other modalities like atherectomy, laser and combine them with what is currently the standard of care, which is drug-coated balloons or drug-coated balloons plus stent, as shared in the study. I just want to congratulate Dr. Ott on her study and encourage future studies from the group. I know the ISAR group is been a phenomenally productive group in coronary intervention and I'm delighted to see they're expanding on the peripheral world.

Dr. Carolyn Lam: I couldn't agree more. Congratulations, once again, for a study that really will impact practice and that we're so proud to be publishing in Circulation.

Listeners, I'm sure you learned as much as me, so please don't forget to tune in next week as well. Thanks.

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