TAVR Valves Compared, and Other Lessons on the Management of AS

This interview is a translation of a video discussion posted on Medscape France. It has been edited for clarity.

Walid Amara, MD: Hello, and welcome to Medscape. I am Walid Amara, and I am pleased to welcome you to coverage of the American Heart Association's (AHA's) 2019 Congress. I'm with Professor Éric Van Belle. Éric, in one of the late-breaking sessions, you presented results from the FRANCE-TAVI registry, which was also published in Circulation. Can you summarize the key points of this presentation?

Self-expanding Prostheses More Harmful Than Balloon Implantables

Éric Van Belle, MD: Transcatheter aortic valve implantation (TAVI) has become the first-line treatment for patients with symptomatic aortic stenosis. In that context, we asked, is there or is there not a class effect with the various prostheses available to treat these patients? That is, if a patient comes in for transcatheter aortic valve replacement (TAVR), are the available prostheses interchangeable?

We know that there are important conceptual differences among these devices. TAVR operators can choose between balloon-expandable devices (eg, SAPIEN-XT and SAPIEN 3 [Edwards Lifesciences; Irvine, California]) and self-expanding devices (eg, Corevalve [Medtronic, Inc.; Minneapolis, Minnesota]). This study was a direct comparison of these two types of prostheses, given that, to date, there have been no large-scale randomized studies to answer this question.

Amara: Often, cardiologists do not pay attention to what device brand, model, et cetera, the patient received. They just look at the final result.

Van Belle: Once you see the finished products, these devices are very different from one another conceptually, even if they are used to treat the same condition. We already knew that self-expanding prostheses are associated with a higher rate of pacemaker use, and we also knew that, in general, they were associated with a higher risk for paravalvular leak, but you need large volumes of data to conduct an all-cause mortality analysis. The objective of FRANCE-TAVI was to approximate, as closely as possible, what a randomized study of the two types of prostheses could have provided.

Amara: What were the results?

Van Belle: In terms of methodology, we started with more than 12,000 patients in the FRANCE-TAVI registry who were treated from 2013 through 2015. We limited our analysis to patients who were treated for native aortic stenosis with either the balloon-expandable or the self-expandable prostheses.

We did propensity matching to get about 4000 pairs of patients who were as similar as possible over 25 clinical, anatomical, or procedural criteria. We also paired the patients so that they were treated around the same time (within 3 months of each other), and then we made an adjustment for the sites, in case there was a site effect. So it is the most robust study possible with the data we had.

The first primary outcome was the combination of paravalvular leak and all-cause mortality in the hospital phase. We found a difference of 60%, to the disadvantage of self-expanding devices, which was quite significant, given the number of patients. The second primary outcome was all-cause mortality at 2 years, with an absolute difference of 3% mortality, again to the disadvantage of self-expanding prostheses, which was also very significant between the two groups. These are rather provocative results. However, this was not a randomized study, so we must be cautious about their interpretation.

Because this was a retrospective study, we could use only the criteria that were entered into the database. There may be some missing criteria that influenced the results or the surgeon's choice of one prosthesis over another, and this could explain some of the difference in outcomes. This limitation is inherent in this type of analysis. What you need to know is that these results are supported by another retrospective study.

Amara: Yes, a study by another French team, Deharo and colleagues, in Marseilles, and published in the same issue of Circulation.

Van Belle: Their results agree completely with those of our study. They included more than 30,000 patients and found a difference in mortality between these two types of prostheses favoring the balloon-expandable device. But here again, we cannot exclude the surgeon's choice and that one prosthesis may have been used more in patients who were sicker at baseline, on the basis of criteria that were not captured.

My conclusion is that it is important to conduct a large-scale randomized study to compare, head-to-head, the two most widely used types of prostheses. We need to determine whether we can offer the two prostheses interchangeably or whether one prosthesis is preferable for a specific patient.

Amara: Can we tell cardiologists now which patients should be referred for TAVR rather than surgery?

Van Belle: FRANCE-TAVI does not cast doubt on TAVR as such. On the contrary, it was conducted in a context where TAVR has become the first-line treatment, equal to or even superior to cardiac surgery for patients considered high-, intermediate-, or low-risk. All the available studies position TAVR as the preferred treatment for patients with symptomatic aortic stenosis. I want to emphasize that the patient must be symptomatic to be offered a valve replacement. We can talk about asymptomatic patients later.

RECOVERY: Early Surgery Versus Medical Treatment for Severe Asymptomatic Aortic Stenosis

Amara: Let's talk about them now, because the RECOVERY study also was presented at the AHA and simultaneously published in the New England Journal of Medicine. It involved truly asymptomatic patients and compared surgery versus conservative treatment.

Van Belle: You may know that another study is under way in the United States, called EARLY TAVR, which randomly assigns patients with asymptomatic aortic stenosis to receive medical treatment or TAVR. We'll have the results in the next year or two.

RECOVERY is a Korean study that began quite a few years ago. They presented the 5-year follow-up results at AHA. It is relatively limited in size. There were 140 patients—70 in each arm—with asymptomatic aortic stenosis but for whom the hemodynamic criteria and the aortic stenosis criteria reflected very severe disease. And if you compare these aortic stenosis severity criteria (the gradient), these patients had more severe aortic stenosis than those in the latest TAVR studies.

Amara: Yes. They had an aortic valve area < 0.75 cm² and a mean transthoracic gradient > 50 mm Hg, so these are patients with very severe stenosis.

Van Belle: These patients had severe stenosis, but all were asymptomatic and were randomly assigned to receive first-line surgery or first-line medical treatment. Of course, there was some degree of crossover, but the key finding is that there was a difference in mortality favoring the group that was offered surgery. There was a lower risk for operative mortality or death from cardiovascular causes with the early replacement of the aortic valve compared with conservative management.

This is the first study to ask whether we can offer valve replacement as first line once the patient's aortic stenosis is considered severe. We are moving toward a new population: the asymptomatic patient.

Post-TAVI Antithrombosis Protocol: Rivaroxaban Is Not Better Than Aspirin in GALILEO

Amara: We're nearing the end of our discussion, and I don't want to finish without saying something about the GALILEO study, which is evaluating the post-TAVR antithrombotic therapy. What did it find?

Van Belle: Currently, it's not clear what the best post-TAVR antithrombotic strategy is, because we don't have precise data on the benefit of one strategy compared with another. In the beginning, we offered clopidogrel; more recently, we returned to aspirin, but it's very hazy.

GALILEO tested rivaroxaban long-term against aspirin, and overall, rivaroxaban was no better than aspirin. It seems that minimal treatment with aspirin is safe, and in the end, I find that satisfying.

The more interesting part of GALILEO is the substudy called GALILEO 4D, which looked at the phenomenon of valve thrombosis. It is a very small study based purely on imaging criteria, but it found that treatment with rivaroxaban prevented the occurrence of valve thrombosis. I still think that rivaroxaban can be put on the back burner because we're not really sure what this valve thrombosis phenomenon is, and whether it's of clinical consequence, but you have to keep it in mind.

Another study headed by Gilles Montalescot and Jean-Philippe Collet, called ATLANTIS, is exploring the same question. We should have those results in about a year.

Amara: Thanks for your insight.

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