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DENVER -- In transcatheter mitral valve replacement (TMVR), valve-in-ring procedures performed were generally safe and feasible, according to a preliminary analysis of the MITRAL study.

But operators had a more challenging time putting transcatheter valves in native valves for mitral annular calcification (MAC).

MITRAL is an investigation of the early experience of TMVR in patients with severe mitral valve disease secondary to mitral annular calcification (MAC) or failed annuloplasty rings. Ninety patients at extreme surgical risk were split evenly into groups of three: those getting treatment on a native mitral valve (for MAC), a valve-in-ring procedure, or a valve-in-valve procedure. Operators used a wide assortment of devices on these patients.

At the conference here, a presentation by Mayra Guerrero, MD, of Evanston Hospital in Illinois, focused on the MAC and valve-in-ring populations.

All valve-in-ring cases were performed via transseptal access. Two out of the 30 patients in this group died in the hospital (one of them for cardiac reasons), with no more deaths to the end of 30 days post-procedure. Other adverse events at 30 days include blood transfusion (20.6%) and acute renal failure requiring new hemodialysis (10.3%).

Technical success reached 70% and was limited by need for second valves. This improved with experience, however, and needing a second valve was not associated with poor outcomes, according to Guerrero. She suggested that transcatheter heart valve design changes -- a longer inner skirt, perhaps -- may further improve technical success.

At 30 days, echocardiograms showed that 75% of the cohort had no or trace mitral regurgitation, indicating that TMVR worked to improve symptoms.

"Transseptal access for valve-in-ring can be achieved in most patients" and "is associated with low 30 day mortality and low complication rate," the presenter concluded, calling this procedure "a reasonable alternative for high surgical risk patients."

On the other hand, TMVR on MAC was a somewhat different story.

With half of procedures performed via transseptal/transapical access and the other half transatrially, five out of the 30-patient group died in the hospital (four of them for non-cardiac reasons). As was the case with the valve-in-ring cohort, there were no more deaths in the overall 3o-day period -- however, some patients required blood transfusions (34%) and experienced hemolytic anemia (11.5%).

Technical success was 73.3%, with left ventricular outflow tract (LVOT) obstruction a common complication that operators encountered (10%). To prevent this, operators in MITRAL are now performing preemptive alcohol septal ablation weeks prior to TMVR, Guerrero noted.

By 30 days, 75% of the MAC group had zero or trace mitral regurgitation.

"TMVR in MAC is a challenging procedure associated with complications," though "outcomes have improved with better patient selection and techniques," Guerrero said. To that end, she noted that cardiac CT is key to better patient selection, while the transatrial approach allows resection of anterior leaflet to decrease LVOT obstruction risk.

"Transseptal valve-in-MAC may become a reasonable alternative for high surgical risk patients with favorable anatomy, but techniques require further refinement," Guerrero concluded. "This is a different patient population on multiple levels in the body. You can fix the valve but you still have to deal with the rest of the body."

Paul Sorajja, MD, of the Minneapolis Heart Institute at Abbott Northwestern Hospital, called Guerrero's MITRAL data "ground-breaking."

"She's testing technology in a racetrack, taking cars and pushing them to the limits. She's taken technology to the extreme of mitral disease and shown that you can use off-the-shelf devices and they can be effective," Sorajja said at a press conference.

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