EuroPCR: Percutaneous Mitral Valves Face Stubborn Obstruction Risk

PARIS -- Technical success of transcatheter mitral valve replacement (TMVR) may be improving with global experience, but the risk of left ventricular outflow tract obstruction is not, a registry study suggested.

Technical success and short-term outcomes tended to track with center experience (for 30-day mortality: 37.5% in lowest tertile versus 21.9% in middle tertile versus 15% in highest tertile), Mayra E. Guerrero, MD, of Evanston Hospital in Ill., reported from the MAC Global Registry at a late-breaking session at EuroPCR.

The stubborn exception seemed to be ventricular outflow tract (LVOT) obstruction, which did not appear to budge no matter the institution's experience. It was as common in the highest as the lowest experience tertile, both coming in at 12.5%.

"The transcatheter valve may intrude by itself on the LVOT, or push the anterior mitral leaflet into the outflow. Future technological designs for TMVR must take this into account," said Scott Lim, MD, of University of Virginia Health System in Charlottesville, who added that "pre-procedure imaging should screen for this possibility."

Lim, who was not involved in the study, told MedPage Today that "we remain as a group on the steep end of the learning curve of this procedure."

Indeed, maintaining that "this was an early experience," Guerrero suggested that TMVR cannot move forward without dealing with LVOT obstruction and figuring out better annulus sizing methods, access sites, and patient selection.

That said, she also noted that alcohol septal ablation is a feasible bailout method when encountering LVOT obstruction.

Guerrero's investigation used data from 47 centers in 11 countries. Patients underwent TMVR with compassionate use of aortic transcatheter heart valves between 2012 and 2016.

Technical success of transcatheter mitral valve replacement (TMVR) was achieved in 75% of patients with mitral annular calcification. A second valve was needed 12.5% of the time due to migration or mitral regurgitation.

Overall, left ventricular outflow tract (LVOT) obstruction with hemodynamic compromise was noted in 10.5% of cases, valve embolization in 3.8%, left ventricular (LV) perforation in 1.9%, and pulmonary vein perforation in 0.9%.

Mean mitral valve gradients fell from 11.45 mmHg at baseline to 4.16 mmHg after intervention, according to Guerrero.

Cardiovascular events arose in 10.6% of patients by 30 days, with LVOT obstruction occurring at a 2.9% rate by then, she said.

The SAPIEN XT and SAPIEN 3 were the most frequent devices used, together accounting for almost all the valves deployed.

Operators tended to favor the transapical approach (about 45% of cases), though Guerrero noted that the trans-septal strategy (about 35%) had been gaining in prevalence as well.

"There is much excitement in the transcatheter heart valve field about the prospect of TMVR, but at present it remains at the forefront of clinical research," Lim commented.

Guerrero pointed to the MITRAL trial, a physician-sponsored IDE pilot study, as the next step for TMVR.

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