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Results of the SCOPE II clinical trial were presented at the TCT Connect 2020 virtual meeting this autumn (14–18 October). The trial compared the use of the Acurate neo (Boston Scientific) transcatheter aortic valve versus the CoreValve Evolut (Medtronic) prosthesis, with primary endpoints including a composite of death and stroke at one year. The results paint a straightforward picture, with Acurate neo failing to demonstrate non-inferiority compared to the CoreValve Evolut device. Coming just 12 months after the presentation of the results of a predecessor trial, SCOPE I, in which Acurate neo failed to meet non-inferiority in safety and efficacy compared to the Sapien 3 (Edwards Lifesciences) device, these findings would appear to represent a significant setback for Acurate neo.
However, according to Nicolas van Mieghem, professor of interventional cardiology at the Department of Cardiology, Thoraxcenter, Erasmus University Medical Center (Rotterdam, The Netherlands), these conclusions are not so straightforward. Speaking to Cardiovascular News, van Mieghem says that the results of SCOPE II merit further discussion, and should potentially lead to a wider conversation about the design of future trials aimed at assessing the efficacy of TAVI devices.
“What was a little bit surprising to me was that SCOPE II did not meet its primary endpoint in terms of non-inferiority, meaning that the Acurate neo turned out not to be non-inferior versus the CoreValve Evolut,” said van Mieghem, offering his analysis of the trial’s findings. “That was a little bit unexpected, but there are some comments to be made about the trial,” he adds.
Firstly, van Mieghem said, it is necessary to consider the type of analysis performed in SCOPE II, pointing out that in the intention-to-treat analysis, death or stroke at one year was 15.8% in the Acurate neo group compared to 13.9% in the CoreValve Evolut group, while in the per-protocol analysis this was 15.3% vs. 14.3% (within non-inferiority limits). “The interpretation depends on the perspective that you take on the trial, and that immediately illustrates its weaknesses,” he says. “I think it is fair to say that the way that the trial was executed did not allow for firm conclusions to be made.”
A further comment to make about SCOPE II is the differing levels of experience with Acurate neo of the centres involved in the trial, says van Mieghem. “As a matter of fact,” he says, “17% of the patients were coming from French centres that had no experience with Acurate, but had experience with Evolut when they entered the trial, so that also makes you wonder, if they were not experts with Acurate, but they were with Evolut—are both treatment arms comparable?”
SCOPE II was designed to explore patients who were at elevated operative risk, but van Mieghem says it is unclear how many patients were screened and subsequently enrolled in the trial. “I think an important aspect when you consider the Acurate neo is what is the phenotype of the patients in terms of anatomy, and how much calcium is there in the aortic root—that is a very important tie-breaker in clinical practice. The amount of calcium will determine whether you would want to use a supra-annular functioning valve. There is no information on that, so it is quite a black box, so to speak.”
This raises an important point that can be applied more widely to the design of TAVI device trials, van Mieghem suggests. “I think we need to better scrutinise the patients that are enrolled in these studies. We need to know more details about who is enrolled and who is excluded,” he comments. “If you look at the TAVI scene, then a more in-depth analysis of the baseline CT, the pre-procedural planning with CT is so important, because it determines how you can anticipate how a valve will work.”
According to van Mieghem, a more favourable approach could be to better define the anatomical traits of the patients being studied, “zooming in” on specific indications—highlighting in particular patients at risk of conduction disorders, or patients with small anatomies, leading to what he describes as conclusions that will help to inform “patient-tailored” valve selections. “What starts to build in my mind is that we need to walk away from these all-comers concepts, it does not exist,” van Mieghem concludes. “I think we should aim for focused trial designs, still comparing one device with another but in well-defined subsets of patients, rather than making it more global.”