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Evolut PRO, the latest addition to the CoreValve line of transcatheter heart valves, doesn't improve on the hemodynamic performance of its predecessor Evolut R, researchers found.

The PRO device is the newest commercially available iteration of Medtronic's self-expanding CoreValve devices for transcatheter aortic valve replacement (TAVR). It is essentially the Evolut R with an outer porcine pericardial wrap at the bottom of the stent frame, a design feature meant to reduce paravalvular leak. Because of this addition, the new device requires a larger sheath size.

Patients getting the Evolut PRO had mean transvalvular pressure gradients reduced to the same extent as peers getting Evolut R, however, and did not show any advantage in their rate of mild paravalvular leakage (16.2% for Evolut R versus 14.9% for Evolut PRO, P=0.794), reported Shazia Afzal, MD, of Germany's University Hospital Düsseldorf, and colleagues in the Nov. 26 issue of .

The findings came from a single-center observational study in which Afzal and colleagues identified patients with severe symptomatic aortic stenosis and high surgical risk who received one of the Evolut stents. The researchers then performed propensity matching to develop two cohorts for comparison, sized at 2:1 for Evolut R versus the PRO model (n=148 and 74, respectively). The two study cohorts were well-balanced except the Evolut PRO recipients had at baseline more atrial fibrillation, less chronic obstructive pulmonary disease, and larger aortic valve areas.

"Because both valves are commercially available but sold at different prices, the pivotal question is whether the Evolut PRO reaches its announced target in a real-world setting," Afzal and colleagues said, concluding that their data "do not support the hemodynamic advantage and propagated superiority" of the PRO's pericardial wrap.

"This fact may also be based on the high-quality standard of the Evolut R platform, which has provided good results for years, the best practice-based pre-procedural CT sizing, and the implantation strategies that pay special attention to PVL [paravalvular leakage] reduction at many European TAVR centers," according to Afzal's group.

In the single-center observational study, Evolut R and Evolut PRO patients shared a similar post-procedural aortic regurgitation index. The former were discharged with a 1.4% rate of moderate aortic regurgitation whereas the latter had none (P=1.000). No Evolut PRO patients were left with severe aortic regurgitation, either.

Major bleeding events occurred at similar rates and neither arm experienced vascular complications.

Importantly, the proportion of patients experiencing conduction disturbances requiring new permanent pacemaker reached 10.8% with the Evolut R and 18.6% with the Evolut PRO (P=0.096).

Evolut PRO procedures were 20 minutes faster and required less contrast agent use, the authors noted.

"Given that the authors matched the patients for LVOT [left ventricular outflow tract] calcification and cover index, both acknowledged risk factors for the occurrence of conduction disturbances after TAVR, it seems intuitive to hold the external pericardial wrap of the Evolut PRO responsible for both of the observed differences: the optimized rate of mild PVL and the slightly increased rate of permanent pacemaker implantation," according to Jan-Malte Sinning, MD, and Alexander Sedaghat, MD, both of University Hospital Bonn in Germany, writing in an accompanying editorial.

Yet certain baseline and procedural differences may have contributed as well, they argued.

"It seems fair to conclude that 'going PRO' in 2018 is an appropriate option to further reduce PVL when using a self-expanding transcatheter heart valve," Sinning and Sedaghat said. Larger registry studies and, above all, randomized studies, are still required to fully evaluate the cost-effectiveness and clinical benefits of the Evolut PRO, they maintained.

Evolut R entered the U.S. market in 2015 and the Evolut PRO in 2017.

Evolut R evaluated in registry study

In a separate study in the same journal, the Evolut R was associated with good hemodynamic and clinical outcomes, according to a registry of patients who underwent TAVR with the device in 2016.

Of the 1,040 patients included in FORWARD -- all presenting with symptomatic aortic valve stenosis or a failed surgical valve -- 98.8% had mild or less PVL (none had severe PVL) 1 year after the procedure. Core lab adjudication revealed that this group had a mean effective orifice area of 1.9 cm² and mean gradient of 8.1 mm Hg by then, reported the team led by Ganesh Manoharan, MBBCh, MD, of Royal Victoria Hospital in Belfast, Northern Ireland.

One-year all-cause mortality was 8.9%, with most deaths attributed to cardiovascular mortality (6.9%). Disabling stroke occurred in 2.1% of cases by 1 year and permanent pacemaker implantation in 19.7%.

Evolut R's pacemaker rate therefore put it somewhere in the middle of the pack, Manoharan and colleagues suggested: worse than the Sapien 3 but better than the Lotus.

"This is the largest to date analysis of 1-year clinical outcomes of this device," said Danny Dvir, MD, of University of Washington in Seattle, in another editorial. "The only finding that seemed suboptimal was the rate of conduction defect requiring a pacemaker: in approximately one out of five patients."

Comparably good results in the U.S. experience of Evolut PRO give hope, Dvir suggested.

"It seems that successive technological improvements and THV [transcatheter heart valve] design iterations may soon lead to minimization of adverse events after TAVR and justify use of this approach in younger and lower risk patient populations," he wrote.

FORWARD was a registry of routine TAVR practice at 53 centers worldwide. Operators had to have prior experience performing at least 50 procedures with a device from the CoreValve family (ten of them with the Evolut R itself).

Registry participants averaged 81.8 years on enrollment and were 64.8% women. The mean Society of Thoracic Surgeons score was 5.5%; New York Heart Association (NYHA) class III or IV symptoms at baseline were noted in 72.0%.

Manoharan's group previously reported a 2.0% rate of 30-day mortality for this group.

After multivariable adjustment, the strongest predictors of mortality at 1 year were:

• Serum creatinine >2 mg/dL at baseline (HR 2.92, 95% CI 1.46-5.82)
• Diabetes at baseline (HR 2.47, 95% CI 1.46-4.17)
• Major vascular complications within 30 days of TAVR (HR 2.26, 95% CI 1.11-4.59)

Eleven of the 16 patients with moderate or more PVL at discharge had another assessment at 1 year: of those, nine had improved in both aortic valve gradient and PVL by 1 year.

By then, 80.5% of all patients had improved their NYHA functional class.

Reliance on observational data is an inherent caveat of the registry study. The investigators acknowledged that a quarter of the cohort lacked usable 1-year echocardiograms.