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The CoreValve Evolut R improved upon the complication rate of earlier transcatheter heart valves, according to two observational studies.

The first, the prospective with 241 participants, showed fairly favorable rates of 30-day adverse outcomes such as all-cause mortality (2.5%), disabling stroke (3.3%), major vascular complications (7.5%), life-threatening or disabling bleeding (7.1%), and new permanent pacemaker implantation (16.4%). Moderate residual paravalvular leak was reported in 5.3% of patients.

Hemodynamics also improved immediately after transcatheter aortic valve replacement (TAVR), with mean aortic valve (AV) gradient reduced from 48.2 to 7.8 mm Hg (P<0.001) and AV area widened from 0.6 to 1.9 cm² (P<0.001), a group led by , of Boston's Beth Israel Deaconess Medical Center, reported in the Feb. 13 issue of JACC: Cardiovascular Interventions.

Device implantation was attempted in 241 elderly patients (average 83.3 years old), all with high surgical risk (mean STS score 7.4%), of whom 237 did get the Evolut R.

The cohort was treated mainly via iliofemoral access (89.5%), and 22.6% got resheathing or recapturing during TAVR.

"The results of this study support the safety and efficacy of this device in patients with severe aortic stenosis with a low frequency of moderate or greater aortic regurgitation and lower requirement for permanent pacemaker due to conduction abnormalities," Popma and colleagues concluded.

"The current study includes only patients with perimeter-based diameters between 18 and 26 mm and does not include an evaluation of this novel design in larger annular sizes," Popma's group conceded, although they noted that larger Evolut R will be tested in the 26 to 30 mm annular range.

Echoes From Across the Pond

Real world results were similar for unselected patients, according to a separate registry study appearing in the same journal.

Major complications for those enrolled in the included cardiac tamponade (0.4%), conversion to sternotomy (0.8%), coronary occlusion (0.8%), major vascular complications (5.3%), acute kidney injury (6.1%), and new permanent pacemaker implantation (14.7%). There were no cases of annular rupture.

A 97.7% 30-day survival rate was associated with the procedure, , of St. George's University Hospitals NHS Foundation Trust in London, and colleagues reported.

Improved or mild paravalvular leak was observed in 92.3% of patients immediately after implantation. Furthermore, average AV gradients fell from 47.0 to 8.3 mm Hg, while average valve area grew from 0.68 to 1.7 cm².

The 264 consecutive patients in the registry were typically elderly (mean age 81.1) and at more intermediate risk (mean STS score 6.0%) when they got TAVR with the Evolut R in 2013-2016.

Most of the procedures were done transfemorally (92.3%) and with mostly successful valve deployment (91.3%).

"This registry represents the largest published real-world experience of the Evolut R valve. The procedural success rate was high and safety was excellent, comparable with previous studies of the Evolut R valve and other second-generation devices," the authors wrote. "The low rate of complications represents an improvement on first-generation devices."

Nevertheless, Brecker's group acknowledged that the registry study only took voluntary participants and that their data were self-reported without core laboratory validation.

Still Room to Grow

Repositionability was a major change made when Medtronic redesigned the CoreValve.

In an , however, , of Ferrarotto Hospital in Italy, suggested that this new feature may have backfired in a way.

"In the present studies, the risk of periprocedural stroke was 3.8% and 3.3%, which are well in line with comparable cohorts from recent registries using previous and new-generation devices. According to these early observations, the majority of new-generation TAVR devices did not seem to provide an incremental benefit in terms of stroke," he wrote.

"Repetitive repositioning of recapturable self-expanding and mechanical expanding designs into the aortic root to obtain optimal valve implant may potentially have played a role in these findings, counterbalancing in some way the benefit of devices with enhanced traceability and lower profile," he continued, albeit acknowledging the speculative nature of the claim.

Barbanti also expressed dissatisfaction with the rates of pacemaker implantation (14.7% in the U.K. registry and 16.4% in the U.S. study) and paravalvular regurgitation seen in these two studies -- especially as TAVR expands to younger and lower-risk patients (the Evolut R is now approved for intermediate-risk patients in Europe).

According to Brecker and colleagues, the issue of paravalvular regurgitation may be resolved with future generations of the Evolut R, which are expected to have sealing skirts.

In addition, data from Popma's study linked paravalvular regurgitation with devices that were too small, Barbanti commented, "supporting the concept of an 'aggressive' annular oversizing with self-expanding valves to achieve better outcomes."

"I personally believe that the improvements reported up to now with the Evolut R are remarkable, but they are mostly the result of the improved release mechanism, which has facilitated achieving optimal implantation depth, rather than the valve itself," the editorialist maintained.

In the end, neither Evolut R nor its competitors are perfect, he suggested, advocating for continued technological advancement. "We have already achieved exceptional outcomes, but this is not the time to rest on our laurels and enjoy our success."