A new study indicates that transcatheter aortic valve implantation (TAVI) with a new-generation device—CoreValve Evolut R (Medtronic) or Sapien 3 (Edwards Lifesciences)—can be used to safely and effectively manage aortic stenosis in patients with large annuli. Gilbert HL Tang (Mount Sinai Medical Center, New York, USA), who presented the study (as a poster) at the 2018 Transcatheter Valve Therapies (20–22 June, Chicago, USA), spoke to Cardiovascular News about the findings.
Overall, what is the incidence of TAVI patients with very large annuli?
It is hard to define as we do not know what percentage of patients with very large annuli receive surgery or medical therapy. In 2017, at Mount Sinai, the percentage of patients who had a 29mm Sapien 3 or 34mm Evolut R device out of all TAVI performed was approximately 20%
Given the move towards treating patients at lower risk, do you think that this incidence is likely to increase?
The incidence may increase because of the higher prevalence of bicuspid aortic valves in younger patients, who are typically at lower risk, and also the majority of younger patients are male. Therefore, we do expect to see more and more patients with large annuli being evaluated for TAVI.
When managing patients with very large annuli, how do operators choose between using a balloon-expandable device and a self-expanding device?
This usually depends on operator preference. At our centre (Mount Sinai), we give consideration to the percentage of oversizing by both annulus and the left ventricular outflow tract (LVOT), and severity and distribution of leaflet, annular and LVOT calcium. Additionally, as in our study, we also review the sinuses of valsalva and sinotubular junction dimensions.
With a small sinotubular junction, we tend to prefer a 34mm Evolut R valve to avoid the risk of balloon-induced injury to the junction (as might occur with the 29mm Sapien 3 valve). One unique feature of the 29 Sapien 3 is you can overexpand it to improve the sealing at the LVOT—provided the LVOT is smaller than the annulus. This has been shown to be feasible in another study that we performed (as published in JACC: Cardiovascular Interventions).
Your study showed that Evolut R was associated, compared with Sapien 3, with more left bundle branch block (LBBB) and new pacemakers but better haemodynamics. What are the implications of this?
If patient has pre-existing conduction abnormalities and there is significant oversizing by perimeter with the 34mm Evolut R device, if anatomically feasible, we would prefer to use the Sapien 3 device.
We found that the rates of new persistent LBBB and need for a new pacemaker with Sapien 3 was significantly lower. This may be particularly relevant for younger, lower risk patients because we are beginning to see increasing evidence that new persistent LBBB is predictive of mortality, sudden cardiac death and rehospitalisation (as shown in the recent meta-analysis and the PARTNER 2A S3i data presented at the 2018 American College of Cardiology Scientific Session).
What further research in this area is needed?
We need to understand the upper limit of annular and LVOT dimensions and other anatomic factors associated with 29mm Sapien 3 and 34mm Evolut R devices to determine if there are predictors of paravalvular leak and LBBB and permanent pacemaker rate since those may have implications in lower risk and younger patients. We also need to understand the behaviour of these two valves in bicuspid anatomy given the increased prevalence of bicuspid valves in younger patients, who usually have larger annuli.
Overall, when managing a patient with very large annuli, what are the key considerations?
I would suggest a detailed analysis of the aortic root anatomy, including annulus and LVOT dimensions and geometry, severity and location of calcium, bicuspid vs. tricuspid valve, sinotubular junction and sinus dimensions, and of course left main and right coronary height. I would also suggest implanting these valves higher (e.g. 80/20 aortic for Sapien 3; 2-4mm depth with 34mm for Evolut R) to improve sealing at the LVOT level and reducing risk of new-persistent LBBB and need for a new permanent pacemaker.