Two registry studies have linked Edwards Lifesciences' transcatheter aortic valve replacement (TAVR) system to better outcomes than Medtronic's rival device.
The studies, which were published in the Circulation journal on Saturday, describe the use of French registry data to compare Edwards' balloon-expandable technology to Medtronic's self-expanding device.
While the data favor Edwards' Sapien valve, the authors of the studies and an accompanying editorial urged caution, noting confounding factors may explain the divergent outcomes. Large, randomized controlled clinical trials are needed to generate stronger evidence, they said.
Edwards' Sapien line of valves and Medtronic's CoreValve devices have grown into major products on the strength of clinical data showing they deliver better outcomes than conventional surgery in many patients. However, there is a lack of data directly comparing the devices, limiting physicians' ability to make informed decisions about which product to choose.
To address that evidence gap, two groups independently analyzed French registry data. The larger of the two studies looked at around 20,000 patients, split evenly between people treated with Edwards' Sapien 3 and Medtronic's CoreValve Evolut R.
The study linked Sapien 3 to significantly lower rates of all-cause death, cardiovascular mortality, rehospitalization for heart failure and post-procedure pacemaker implantation.
In the second study, researchers compared outcomes from close to 4,000 patients treated with Edwards' Sapien line of valves to the same number of people treated with Medtronic's CoreValve. The comparison linked Sapien to a lower risk of paravalvular regurgitation, in-hospital mortality and two-year mortality.
Taken at face value, the data appear to show Sapien delivers better outcomes than CoreValve and validate some ideas about their different designs, such as the belief that self-expanding valves are more susceptible to problems including paravalvular leak and, by extension, more likely to result in hospitalization due to heart failure.
However, the results may reflect confounding factors rather than differences in the effectiveness of the devices. For example, the authors of the larger study note that CoreValve uses a smaller introducer sheath and there is an idea that its self-expanding design cuts the risk of annulus rupture. These factors could lead surgeons to use CoreValve in people with major aortic annulus calcifications or small, complex femoral access who have worse outcomes due to their underlying conditions.
In light of such concerns, which are inherent to registry-based analyses, the authors interpreted the findings cautiously. Two cardiologists took a similar position in an accompanying editorial.
"Performing head-to-head device comparisons can sometimes resemble entering a minefield, so the authors should be commended for their courage as well," they wrote. "Nevertheless, the limitations of such registry-based analyses are obvious, and the findings should therefore be considered thought-provoking but by no means definite."
The authors of both studies and the editorial independently called for large, randomized controlled clinical trials comparing balloon-expandable and self-expanding TAVR devices. Having data on the comparative effectiveness of competing devices could prove particularly valuable as TAVR moves into younger, lower-risk patients in whom predictable, overwhelmingly positive outcomes will be needed if the approach is to win market share.