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Jan 30, 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 Centre and Duke-National University of Singapore. Our featured discussion today relates to 20 year outcomes after mitral valve repair versus replacement for severe degenerative mitral regurgitation.

                                                But first, here's your summary of this week's issue. The first paper suggests that agonistic angiotensin receptor autoantibodies may be biomarkers of adverse outcomes. In this study from first author Dr. Abadir, corresponding author Dr. Fedarko, and colleagues from Johns Hopkins University School of Medicine in Baltimore, Maryland, authors developed a quantitative immunoassay for measuring agonistic angiotensin AT1 receptor autoantibodies in the serum.

                                                They then assessed its operating characteristics in a discovery group of 255 community dwelling adults from Baltimore and validated these findings in a second group of 60 individuals from Chicago. They found that AT1 receptor autoantibody levels were significantly associated with higher levels of inflammatory cytokines, weaker grip strength, slower walking speed, higher risk for frailty, more falls and increased mortality.

                                                Furthermore, chronic treatment with angiotensin receptor blockers, it attenuated the AT1 receptor autoantibody association with decline in grip strength and increased mortality. These results therefore suggest that followup studies and intervention trials in chronic inflammatory diseases should test whether AT1 receptor autoantibody levels can be used to stratify patient risk and whether they can be used to identify patients who may benefit from angiotensin receptor blocker treatment.

                                                The next paper suggests that baseline target mismatch on CT perfusion imaging may predict the response to tenecteplase in ischemic stroke. Dr. Bivard and colleagues from John Hunter Hospital University of Newcastle in Australia pooled two clinical trials of tenecteplase compared with alteplase for the treatment of acute ischemic stroke.

                                                Baseline CT perfusion was analyzed to assess if patients met the diffused two target mismatch criteria. These criteria are absolute mismatch volume of more than 15 mL, mismatch ratio of more than 1.8, baseline ischemic core less than 70 mL and volume of severely hypoperfused tissue less than 100 mL.

                                                Among 146 pooled patients, 71 received received alteplase and 75 received tenecteplase. Overall tenecteplase treated patients had greater early clinical improvement by NIH Stroke Scale change and less parenchymal hematoma, but did not show a significant difference in three month patient outcome by the Modified Rankin Scale.

                                                74 of the 146 patients met target mismatch criteria. It was only among these patients with target mismatch that treatment with tenecteplase result in greater early clinical improvement and better late independent recovery than those treated with alteplase. In summary, tenecteplase may offer an improved efficacy and safety profile versus alteplase, benefits that are possibly exaggerated in patients with baseline CT perfusion defined target mismatch.

                                                The next study is the first to provide a comprehensive analysis of circulating metabolite levels and relate these to clinical outcomes in patients with pulmonary arterial hypertension. First author Dr. Rhodes, corresponding author Dr. Wilkins and colleagues from Imperial College London conducted a comprehensive study of plasma metabolites using ultra-performance liquid chromatography mass-spectrometry in 365 patients with idiopathic or heritable pulmonary arterial hypertension and 121 healthy controls.

                                                They found that increases in circulating modified nucleosides originating from transfer RNAs, energy metabolism intermediates, tryptophan and polyamine metabolites and decreased steroids, sphingomyelins and phosphatidylcholines independently discriminated pulmonary arterial hypertension from controls and predicted survival. Furthermore, correction of metabolite levels overtime was linked to better clinical outcomes and patients who responded well to calcium channel blocker therapy had metabolic profiles comparable with healthy controls, thus these findings suggest that monitoring plasma metabolites overtime could be useful to assess disease progression and response to therapy in pulmonary arterial hypertension. Therapeutic strategies targeted against metabolic disturbances, particularly translational regulation and energy metabolism, may merit further investigation in pulmonary arterial hypertension.

                                                The final study takes a contemporary look at age associated changes in left ventricular diastolic function. Dr. Shah and colleagues from Brigham and Women's Hospital in Boston, Massachusetts related diastolic measures including tissue Doppler E prime, E to e prime and left atrial size, to the risk of heart failure hospitalization or death in 5801 elderly participants in the ARIC study. They further defined sex-specific 10th percentile limits in 401 participants free of cardiovascular disease or risk factors. They found that each diastolic measure was robustly associated with incident heart failure hospitalization or death. Reference limits for E to e prime and LA size were generally in agreement with existing guidelines, whereas limits for tissue Doppler E prime were substantially lower at 4.6 for septal E prime and 5.2 for lateral E prime in the ARIC study compared to 7 and 10 respectively in international guidelines. Compared to the guideline cut points, the ARIC base limits improved risk discrimination and reclassified over one-third of the study population as having normal diastolic function. These findings were further replicated in the Copenhagen City Heart Study.

                                                In summary, this study suggests that a decline in left ventricular longitudinal relaxation velocity occurs maybe as part of healthy aging and is largely prognostically benign. This supports the use of age-based normative values when considering an elderly population.

                                                Well, that wraps it up for the summaries, now for our featured discussion.

                                                Today we are discussing the very important result of the mitral regurgitation international database and we have with us today no other than the corresponding author Dr. Jean-Louis Vanoverschelde, and he is from University of Louvain in Brussels. Welcome Jean-Louis, I made it.

Dr Jean-Louis Vanoverschelde:  Hey, how are you?

Dr Carolyn Lam:                Thank you so much for joining us. Also joining us today is Dr. Victoria Delgado, associate editor from Leiden University Medical Center in the Netherlands. Welcome Victoria.

Dr Victoria Delgado:        Hello. Thank you very much for having me in this podcast.

Dr Carolyn Lam:                So, severe degenerative mitral regurgitation with flail leaflets, a very important condition and your study, Jean-Louis, really provides important clinically applicable information. Could you please address our clinicians out there with a take home message from your paper.

Dr Jean-Louis Vanoverschelde:  Well, the take home message is very easy, once this condition needs to be operated on, there are really two options, one which is to repair the valve and keep the native tissue and the other is to replace the valve and trash the native tissue if I can say so. The results of the study are really clear. There is a major survival advantage by repairing the valve as opposed to replacing it. So for everyone of those who have degenerative mitral regurgitation with flail leaflets, the best treatment option is mitral repair.

Dr Carolyn Lam:                Now these results came from a multi-center registry of thousands of patients. I was really struck with the duration of the study. I think that's something that's really novel. You had a 20 year follow up but also patients were recruited from 1980 all the way to 2005, am I right? So could you expand a little bit about the possibility of techniques changing during that period?

Dr Jean-Louis Vanoverschelde:  Although there has been subtle changes in the practice, the basic principle have remained the same. So we have not really accounted for these changes in the practice over time, with regard to what happened to mitral valve replacement, clearly the prostheses that were there 30 years ago are not the same as the ones that are currently implanted to the patients, but none the less when we performed an analysis, a sensitivity analysis to look at whether the results were different from 20 years ago compared to those that were more recent, we found exactly the same result.

Dr Carolyn Lam:                Yes, I thought that was a very important sensitivity analysis. Tell us a bit more about the propensity score matching as well because another thing people will be thinking is, you know, this is a registry, huge numbers very important but obviously there would be differences in indication for repair versus surgery.

Dr Jean-Louis Vanoverschelde:  For sure, the fact is that there are statistical means that allow you to mimic not to be the exactly the same as, but to mimic randomization and it is the propensity score matching. That means that you perform a prior analysis that will identify similar patients in the two cohorts and match them so that you are basically having the same kind of patients that are treated with two different ways. So it's not randomization but it’s getting close to randomization when you use cohorts like the one from the MIDA registry.

Dr Carolyn Lam:                Perfect. Victoria, did you take the same take home messages and are you applying this clinically? I noticed that you invited an editorial, a lovely editorial on this paper as well, so please share your thoughts.

Dr Victoria Delgado:        Yeah, I share the same take home message that Dr. Vanoverschelde has outlined. I think that this is very important article, it's a landmark article highlighting one of the most important things that mitral valve repair should be probably the standard of care for patients with severe mitral regurgitation without degenerative cause with a flail and the article basically what it does is also endorsing the recommendations of current guidelines highlighting the value of mitral valve repair. Of course that mitral valve repair should be performed in centers with experience and with good durability of these repairs, so the centers need to have a good heart team where they can analyze their results in such a way like the MIDA registry has done demonstrating a good durability of the repair.

Dr Carolyn Lam:                And do you have anything to add to that Jean-Louis?

Dr Jean-Louis Vanoverschelde:  No, I think basically Victoria very well summarized the basic features not only of the paper itself but also of the condition and what currently is in the guidelines. In fact, the guidelines have already said that we should be preferring mitral valve repair over replacement, but the data on which this was based were probably not as conclusive as the one that are provided by this analysis of our registry, so I think it's really reinforcing the idea that we should go ahead and try to perform repair as much as possible, now with a caveat of course that the surgeons need to be skilled enough to perform that. But with the type of differences that we see in survival between the two cohorts I think that if a surgeon does not feel comfortable with repairing the valve and would rather replace it, he might refer the patient to another surgeon that is capable of repairing the valve. The impact and outcome is such that I think this really supports the idea that the patient should be referred to high volume and skilled centers.

Dr Carolyn Lam:                Could you give us an idea of what kind of impact you're talking about, what kind of numbers that you see?

Dr Jean-Louis Vanoverschelde:  It's the same in all the analysis, whether it's in the overall population or in the matched cohorts by 20 years, we have something like 20 to 25% survival difference, absolute survival difference between the two groups. So it's a reduction of mortality approximately by half if you perform repair compared to replacement, and it is increasing with time, so it's not something that is only present in the first years but is increasing with time, so it's about 20 to 25% absolute difference between the two cohorts.

Dr Carolyn Lam:                That truly is remarkable. Congratulations again on such a landmark paper like Victoria said. Now to either of you, question that's a bit left field maybe, but what do you think the role is now for percutaneous techniques of mitral valve repair or replacement then?

Dr Jean-Louis Vanoverschelde:  That's an interesting question. I think that if you really look far away into the future probably everything at some point in time will be percutaneous. At this stage I’m not sure that the percutaneous technique able to mimic what we can do with surgery in terms of mitral valve repair. So, it's an alternative to surgery in patients who are inoperable. In those who can undergo a surgical mitral repair, my first choice will certainly be to go surgically rather than percutaneously, at least right now.

Dr Carolyn Lam:                Victoria?

Dr Victoria Delgado:        I also agree with those comments. I think that now we have a lot of possibilities to treat these patients but the most important thing is to have the entire clinical picture of the patient, to see the pros and cons of preparing the patient for surgery or for percutaneous valve. There should be also an integration of imaging to know which is the cause of the valve dysfunction and to see whether the anatomy could be easily repaired by surgery or instead if the patient has contraindication for surgery, if it could be repairable as well with transcatheter therapy. But then for that I think that is really important and this is what the editorial also highlights, the role of the heart team, where there are different specialist surgeons, clinical cardiologists, heart failure specialists, imaging specialists that can integrate the entire information of the patient in order to select the most appropriate therapy. But still for patients who do not have contraindications for surgery who have repairable valve and as you can see from this registry, the percentage of repairability is quite high, I would still refer the patient as well for surgical valve repair.

Dr Carolyn Lam:                You heard it right here. Thank you so much for joining us today and please don't forget to tune in next week.

 

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