Dr. Tamim Nazif presented “Progress in Balloon-Expandable TAVR: Sapien X4 and the ALLIANCE Trial” at the TVT conference on June 8th in Phoenix, Arizona. The Sapien transcatheter heart valve (THV) (Edwards Lifesciences) was first launched in 2007 and the current commercially available iteration is the Sapien 3 valve, which offers a cobalt chromium stent frame, Resilia tissue (available as of 2022), a paravalvular leak (PVL) design solution, and valve sizing from 20-29 mm.

“The impressive improvements in the technology have been dovetailed with increasingly impressive clinical outcomes data,” said Dr. Nazif. In the PARTNER 3 trial, the Sapien 3 valve showed a reduction in the primary endpoint (death, stroke, and rehospitalization) versus surgery, at 8.5% versus 15.1% (P>.001), respectively, at one year. Sapien also demonstrated early and durable results for quality of life and economic benefits. Future valve design will look to improve procedural optimization of transcatheter aortic valve replacement (TAVR) and lifetime management of the aortic stenosis patient. The index procedure benefits for a next-generation THV, said Dr. Nazif, should include the ability to do an easy, safe, and reproducible procedure with personalized valve sizing, decreases in PVL, and a lowering of conduction disturbances, decreasing the need for a pacemaker. In the long term, needs include the extension of valve longevity, maintenance of coronary access should patients require future percutaneous coronary intervention, and planning for THV-in-THV procedures.

The Sapien X4 THV system repeats the Sapien 3’s cobalt chromium stent frame, but is redesigned to allow for adjustable sizing. “The size the valve is deployed at can be titrated to the patient’s individual anatomy,” said Dr. Nazif, “while maintaining valve performance across the entire diameter range.” Cell design remains open to allow for coronary access, features the Resilia tissue, and has enhancements to the outer polyethylene terephthalate (PET) skirt to minimize risk of PVL. Resilia tissue is also available on the Sapien 3 THV, and the hope is that this treated tissue will lead to increased valve durability. Sapien X4 comes in 3 valve sizes, but because of its ability to provide personalized valve sizing, 16 deployment diameters (0.5 mm increments) are available (in comparison to only 4 valve sizes available with the Sapien 3 Ultra Resilia valve). An increased ability to personalize sizing with the Sapien X4 is a welcome development. Dr. Nazif noted that “people have tried to do it commercially with valve offsizing, adding or subtracting volume, but we need to bear in mind this has never been recommended and may result in unpredictable outcomes.” The Sapien X4 delivery system is similar to the current Commander delivery system but offers on-balloon valve preparation and the need for the alignment step in the descending aorta is no longer required. There is also the addition of a valve rotation control to aid in achieving commissural alignment.

The Sapien X4 THV is being tested in the ongoing ALLIANCE clinical trial, which is a prospective, single-arm, multicenter study evaluating safety and effectiveness. The trial includes over 900 patients with severe calcific aortic stenosis at all surgical risk levels, with tri- or bicuspid anatomy. The primary endpoint will be the nonhierarchical composite of death or stroke at one year, compared to controls from PARTNER 2 and PARTNER 3. Enrollment began in June 2022  and continued for approximately 6 months. After high push forces were observed during advancement of the delivery system through the sheath in a minority of cases, a voluntary pause was implemented in December 2022 to investigate. A sheath-based solution was implemented, achieved, and enrollment is anticipated to resume in the near future.

Dr. Nazif concluded by sharing two cases. The first case illustrated the Sapien X4 THV’s personalized sizing and was a young, low-risk patient with heavily calcified tri-leaflet anatomy. Annular area was 576.1mm², “a tricky in-between size,” noted Dr. Nazif. “In the current practice, you might use a 29 valve but you would be about 15% oversized in calcified anatomy. You might use a 26 mm; you’d be undersized.” With the Sapien X4, sizing was titrated to 27.5 mm, only 3% oversized. An excellent outcome was achieved by echo and angiography, with only trace PVL. The second case illustrated Sapien X4’s ability to achieve commissural alignment and maintain coronary access. This was an 88-year-old woman with some previous coronary disease. She also had heavily calcified tri-leaflet anatomy but with a very small annulus at 350.2 mm². The Sapien X4 was sized at 21.5 mm, achieving 4% oversizing. Due to the effaced sinus’s relatively low sinotublar junction, the valve could be rotated to achieve commissural alignment. This was done by first going to the c-mark on the outside back handle that also indicates the direction of turn. The c-mark is able to be visualized on fluoroscopy. The next step is to unlock the knob on the back handle, turn the handle, and watch the “c” rotate in real time on fluoroscopy. Once the appropriate alignment is achieved, the valve can be deployed. At the outflow of the valve, the Sapien X4 also has new markers for the commissures of the valve. In this final case, a postoperative CT demonstrated that the valve was well aligned at only 13 degrees off the true commissure of the native anatomy, with wide clearance of the left main coronary artery.

Find more: 
TVT Newsroom (With a Special Focus on TAVR)

Find Dr. Nazif’s slides here.