The results from a new registry study offered a mixed safety profile comparing Medtronic’s (NYSE:MDT) and Edwards Lifesciences’ (NYSE:EW) rival 1st-generation transcatheter aortic valve implantation systems.

Patients in the study who received Medtronic’s CoreValve implant were more likely to have aortic regurgitation (AR) following surgery, but AR was associated with a "significantly worse outcome" only in Sapien patients, according to the study. Overall, mortality rates were the same across both devices.

The CoreValve implant is a self-expanding valve where Sapien is expanded with a balloon, but it’s not clear that the different implantation methods are related to the AR-patient outcomes. Patient differences failed to account for the mortality difference.

"It may be that there is more AR early with CoreValve but this decreases as time goes on with further expansion of the prosthesis," lead author Dr. Philip MacCarthy told TCTMD.com. "It may also be an artifact relating to how the AR was measured in the presence of different devices (eg, more acoustic shadowing with one or the other devices), or it may be a mechanism that we do not yet know about."

It’s no secret that early TAVI devices posed a greater risk of leaving patients with AR, and subsequent generations have taken steps to address the issue. Previous studies have also reported the greater AR risk with the 1st generation CoreValve, but the new report is among the 1st to find a greater mortality risk with AR following Sapien.