This content is only for readers outside of the US as it discusses a device that is not FDA approved.
Results from the SAVI-TF Registry1, which was recently published in JACC: Cardiovascular Interventions, show that the ACURATE neo (Boston Scientific) transcatheter aortic valve implantation (TAVI) device is associated with favourable clinical and echocardiographic outcomes at one year (8% mortality, 2.3% disabling stroke, and 9.9% pacemaker rate). Cardiovascular News reviews the unique design features of the valve and explores their potential benefits over other valve designs.
ACURATE neo is a self-expanding valve that is deployed via a “two-step”, “top-down”, approach. Won-Keun Kim (Department of Cardiology, Kerckhoff Heart and Lung Center, Bad Nauheim, Germany), the lead author of the paper on the SAVI-TF one-year results, believes that this deployment approach is a “very crucial feature” of the device. He explains: “In contrast to other self-expanding devices, where the release starts in the inflow area, the first step opens the outflow part of the ACURATE neo. As soon as the correct position has been verified, step two can be deployed for opening of the lower crown and for full release. This top-down principle ensures undiminished aortic flow throughout the entire deployment with constant haemodynamic stability—thus, eliminating an obstructive phase that is seen with other self-expanding devices. Furthermore, this process allows for a very precise and reliable positioning of the device.”
In addition to the two-step, top-down deployment approach, ACURATE neo is a supra-annular valve rather than an intra-annular valve. Kim believes that supra-annular valves have potential advantages over intra-annular ones. “We know that transvalvular gradients are lower in supra-annular valves and this applies to TAVI devices as well as for surgically implanted valves. Mean gradients might play a role for long-term performance and durability, of which currently there is only limited data available.” Indeed, Mauri et al. compared outcomes of patients with small aortic annuli who underwent TAVI with the ACURATE neo with those who underwent TAVI with SAPIEN 3 (Edwards Lifesciences). They found that the
ACURATE neo device was associated with significantly lower mean transvalvular gradients (6.6mmHg vs. 17.5mmHg; p<0.008) and larger indexed effective orifice areas (1.01cm²/m² vs. 0.74cm²/m²; p=0.031) at one year, resulting in lower rates of severe prosthesis-patient mismatch (3% vs. 22%; p=0.004). “These results emphasise the need of careful prosthesis selection in each individual patient,” Mauri et al. conclude.2
Excellent safety and efficacy despite design “disadvantages”
Compared with some other valves available, ACURATE neo has some potential disadvantages—for example, it is not recapturable. However, the unique design features of the device mean that these “disadvantages” may only be theoretical. The 30-day outcomes of the SAVI-TF registry, of the first 1,000 patients, show that procedural and device success was achieved in 98.7% of patients. Additionally, device usage time was an average of only 6.5 minutes.3 Kim attributes this finding to the “trackability of the delivery system and the aforementioned straightforward and accurate deployment mechanism”. He adds: “In experienced hands, it is possible to implant the device in a much shorter time frame. This would be particularly valuable in patients with comprised haemodynamics because of severe aortic regurgitation following balloon valvuloplasty (which requires that the valve is implanted as rapidly as possible).”
No randomised trial—at least, not one with published results—has directly compared ACURATE neo with valves such as SAPIEN 3 or CoreValve (Medtronic), but SAVI-TF does provide some insight into how it measures up against other valves. In fact, Kim observes that the one-year mortality (8%) seen with ACURATE neo in SAVI-TF is “much lower” than that seen in post-market registries both for SAPIEN 3 (12% in the SOURCE 3 registry) and for CoreValve (16 % in the Advance registry). He says: “In my opinion, the ACURATE neo is the most balanced and comprehensive device and covers most aspects of procedural success, which distinguishes it from other TAVI valves. Whereas most people would primarily look at the final aortogram to evaluate the performance of a transcatheter heart valve, I believe looking beyond that is necessary.”
Furthermore, in addition to its procedural success rates, ACURATE neo has notably one of the lowest pacemaker rates (9.9%) seen with a TAVI valve. Kim comments that this “can be largely attributed to the specific design with less protrusion into the left ventricular outflow tract and its X-shape that allows a more controlled distribution of the radial force”. He adds the low pacemaker rate has been achieved without compromising the rate of paravalvular leak, which he says is “acceptable” and “non-inferior to devices with a much higher radial force”; in SAVI-TF, the overall rate of greater than mild aortic regurgitation was 3.6% at one year. ACURATE neo also has, according to Kim, a favourable haemodynamic profile and only “a very small risk” of coronary obstruction.
The next steps for ACURATE neo
While the SAVI-TF registry provides some indication of how ACURATE neo measures up against other devices, direct comparisons are still needed. Therefore, the ongoing randomised controlled SCOPE trials are exploring the outcomes of the device alongside those of the current market leaders (SAPIEN 3 and CoreValve Evolut). Kim, who is one of the investigators in these trials, states: “The SCOPE trials are being conducted in several European countries and are enrolling patients to compare
ACURATE neo with SAPIEN 3 (SCOPE I) and the CoreValve Evolut platform (SCOPE II). We already know from retrospective analyses that overall device success will probably be similar, but there may be individual differences regarding pacemaker rate, paravalvular leakage, gradients, etc. However, our focus with these studies is not whether one device is better than the other overall but which device is better for which patient. With these studies, we hope to be able to provide an optimised prosthesis selection tailored to the individual anatomy and comorbidities of each patient.”
Looking to the future, Kim does believe that lessons can be learnt from other devices and be incorporated into the design of ACURATE neo. He explains that, at present, it does not have an enhanced external cuff, which he observes is a feature that “has been successfully implemented in the SAPIEN 3 device”—a device that “has one of the lowest rates of paravalvular leakage”. “In this respect, there is some room for improvement with ACURATE neo. Nonetheless, compared with contemporary TAVI devices, the risk of paravalvular leak with the device is comparable.”
The next-generation ACURATE neo2 aortic valve system is currently in development and this will feature an enhanced sealing technology. It also has a new radiopaque marker that is designed to facilitate even better positioning. The CE-mark trial for this valve has completed enrolment.
References
- Kim WK, Hengstenberg C, Hilker M, et al. The SAVI-TF Registry. JACC: Cardiovascular Interventions 2018; 14: 1368–74.
- Mauri V, Kim WK, Mohammed A, et al. Short-term outcome and haemodynamic performance of next-generation self-expanding versus balloon-expanding transcatheter aortic valves in patients with small aortic annulus. Circ Cardiovasc Interv 2017. Epub.
- Möllman H, Hengstenberg C, Hilker M, et al. Real-world experience using the ACURATE neo prosthesis: 30-day outcomes of 1,000 patients enrolled in the SAVI-TF registry. EuroIntervention 2018; 13: e1764–70.
