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As transcatheter aortic valve implantation (TAVI) continues to expand into a younger, lower surgical risk patient population, several key factors become central to valve selection, Darren Mylotte (Galway University Hospitals, Galway, Ireland) tells Cardiovascular News. Most prominently among them are the durability of the prosthesis and sustained haemodynamic performance, as well as other important factors. Here, Mylotte discusses optimal TAVI device selection, considers the features and data behind the latest-generation Evolut PRO+ (Medtronic) device and outlines the cusp overlap technique—a TAVI technique designed to help implanters assess and achieve the target implant depth in order to reduce interaction with the conduction system.
“There are several factors,” comments Mylotte, when explaining the important items to consider in the selection of a suitable TAVI device across all risk profiles. “There may be specific concerns you would have regarding the size of the patient’s anatomy regarding calcification—be that in the left ventricular outflow tract (LVOT) or the leaflets—and whether there are specific concerns regarding the possibility of coronary artery occlusion, and of course vascular access,” he adds.
For those in the lower risk bracket, there are additional factors to consider, according to Mylotte. “In low-risk patients you want to ensure that you have got the right valve in your hand to ensure that you get a good procedural outcome,” he says. “Beyond the procedure you of course want to make sure that you have the appropriate result for your patient in the long term, and that really comes down to a couple of different things: the absence of a permanent pacemaker, patient-prosthesis mismatch, or paravalvular leak, as well as good haemodynamics and access to the coronary arteries in due course, if it is required.”
Haemodynamics are crucial, Mylotte comments, and this is one area that the Evolut system comes into its own. Results from the OPTIMIZE PRO clinical study, a postmarket, prospective multicentre study, covering 46 sites in the USA and Canada, and up to 15 sites in Europe, are the latest data available to document the use of the self-expanding, supra-annular Evolut PRO and PRO+ TAVI systems—with interim, 30-day results from 171 patients with symptomatic severe aortic stenosis, recently presented at the Society for Cardiovascular Angiography and Interventions 2021 scientific sessions (SCAI 2021, 28 April–1 May, virtual). Among the headline findings, the results paint a favourable picture for the haemodynamic performance of the latest-generation Evolut devices, which demonstrated low mean gradients (8.1mmHg) among the patients studied. “The device probably has best-in-class haemodynamics, which are absolutely relevant to avoid patient-prosthesis mismatch and hopefully to give us good durability of the system,” notes Mylotte.
Evolut PRO+ comes in four valve sizes—23, 26, 29, and 34mm—with an external tissue wrap and an integrated, inline sheath, allowing physicians to treat patients with a range of anatomical variations. The system uses an external pericardial tissue wrap that provides advanced sealing for the largest indicated patient treatment range. Evolut PRO+ also has a reduced delivery profile for 23–29mm valves, indicated to treat patients with vessels as small as 5mm. Alongside favourable haemodynamics, the interim results from OPTIMIZE PRO also demonstrate excellent safety outcomes with 0% death or disabling stroke, a low pacemaker rate (8.8%), and low rates of residual total aortic regurgitation with the majority of subjects having none/trace (80.4%), and the rest mild (19.6%) at discharge. Patients also experienced an expedited discharge with a median hospital length of stay of one day.
One of the important areas of study in OPTIMIZE PRO was the use of varied procedural approaches to assess their impact in improving patient care. Among them are the cusp overlap technique which has the potential to lower the risk of interference with the conduction system by providing a more accurate assessment of valve depth.
“The cusp overlap technique allows us to implant more accurately where we want to implant, and as a consequence of that, end up with a lower rate of permanent pacemaker insertion using this system,” says Mylotte, explaining the merits of the cusp overlap technique. The technique has similarities to an RAO caudal approach, Mylotte notes, adding that this allows for greater certainty over implant depth, particularly on the non-coronary cusp, where the intrinsic conduction system tends to lie.
“Compared to the traditional three-cusp implantation technique, the cusp overlap or the RAO-caudal technique allows you to understand your true depth of implant and therefore give you a more accurate deployment,” Mylotte adds. “Therefore, if you are 3mm in the cusp overlap technique, you are probably 3mm deep. On the other hand, with the traditional three-cusp technique when you look in the LAO-cranial view you tend to foreshorten the left ventricular outflow tract, and your depth of implant is much less certain.”
Discussing the outcomes achieved with cusp overlap using the Evolut system, as demonstrated in OPTIMIZE PRO, Mylotte commented that there is a notable impact on pacemaker rates. However, he noted that this is predominantly seen in centres where the technique is well embedded, and cautioned that although the technique is simple to perform, a learning curve is to be anticipated.
He says: “The thing that struck me is that in good centres, which have been using this technique for a while, they have universally very low pacemaker rates. On the other hand, there were two groups of newer centres: those that stuck rigorously to the new implantation technique and also reduced their pacemaker rates quite considerably, and others that found it difficult to transition and continued to experience higher pacemaker rates.”
The technique comes with a learning curve, Mylotte explains, but once this is overcome, the benefit is tangible. “Once you get it, you will see your pacemaker rate drop quite considerably,” he concludes.
