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SAN FRANCISCO -- Operators had a favorable early experience using the Tendyne transcatheter mitral valve replacement (TMVR) system for severe mitral regurgitation (MR) and mitral annular calcification (MAC), according to observational data from the SUMMIT program.

Among a 100-person roll-in cohort -- made up of the first one or two Tendyne patients from each of 72 sites -- survival was 74.3% at 1 year. The incidence of disabling stroke was 5.4%, myocardial infarction 2.3%, and post-op mitral reintervention 2.2% during this period, reported Jason Rogers, MD, of UC Davis Medical Center, here at the Transcatheter Cardiovascular Therapeutics (TCT) meeting hosted by the Cardiovascular Research Foundation.

Another SUMMIT investigator, Vinod Thourani, MD, of Piedmont Heart Institute in Atlanta, presented good 30-day outcomes in a separate cohort of 103 individuals with severe MAC who underwent Tendyne TMVR for mitral regurgitation or mitral stenosis.

All-cause mortality reached 6.8% (all of those being cardiovascular deaths), disabling stroke 1.0%, myocardial infarction 1.0%, and post-op mitral reintervention 2.0% at 30 days in this cohort.

Both roll-in and severe MAC cohorts had zero major device thrombosis, while the former did have minor clots in 2.3 of cases. Major bleeding rates were 32.4% at 1 year for the roll-in group and 21.4% at 30 days in severe MAC.

The 1-year data in severe MAC are still being generated and will be presented at a later time, Thourani told the audience.

Rogers and other session speakers emphasized that the MAC population has a strong clinical need for a device like the Tendyne.

"This will fit very well into our armamentarium. This for me will be first-line when a patient comes in with MAC," Thourani said.

Tendyne is an investigational tri-leaflet bioprosthetic valve with inner and outer frames tethered to an apical pad placed over the ventricular access site. Although dubbed a transapical procedure, it is really implanted surgically after a thoracotomy. A redesign for a transfemoral approach would not be possible, Rogers said.

"What an absolute pleasure to be a mitral surgeon at a meeting where you're presenting a solution to something we find incredibly challenging. There's no great transcatheter option for MAC. There's no great surgical option for MAC," commented TCT session discussant Joanna Chikwe, MD, of Cedars-Sinai Medical Center in Los Angeles.

She nevertheless called out the high screening failure rate in SUMMIT's MAC cohort: of 474 patients screened, 120 were approved for trial, and 103 ultimately met all the criteria and got the Tendyne.

Thourani acknowledged that the major drivers of the 75% screening failure were insufficient neo-left ventricular outflow tract (neoLVOT) and annular dimensions being too small or large. According to Rogers, adjunctive therapies such as anterior leaflet splitting before Tendyne implant may expand the number of patients that can be treated and allow more screen passes in future studies.

is the ongoing trial comparing Tendyne against the MitraClip transcatheter edge-to-edge repair (TEER) in patients with moderate-to-severe MR or symptomatic mitral valve disease due to severe MAC. There are 72 sites participating across the country and study completion is expected in 2028.

found TMVR was associated with better secondary MR reduction and superior symptom improvement compared with TEER, despite an initial disadvantage in survival.

Whereas the randomized SUMMIT cohort is enrolling only patients deemed eligible for TEER, the nonrandomized roll-in group had two out of three individuals unsuitable for TEER.

The roll-in patients averaged age 75 and 54% were men. Etiology of MR was primary in 29.6%, secondary in 69.4%, and mixed in 1.0% of cases. The mean STS-PROM was 6.5%, Rogers reported.

In the roll-in experience, procedural survival was 100% and technical success 94%. Tendyne recipients had MR severity go from baseline grade 4+ in 69% of patients and 3+ in 29.0% to 97.7% none/trivial at 1 month postprocedure and 89.5% none/trivial at 1 year.

Also at 1 year, echocardiographic assessments showed a drop in left ventricular ejection fraction (LVEF; from 47.6% to 41.0%), an increase in LVOT gradient (1.5 to 1.9 mmHg), and no significant change in mitral valve (MV) gradient (3.0 to 3.3 mmHg).

Only after trial operators completed one or two Tendyne TMVR procedures were they then allowed to try their hand in severe MAC.

Thourani reported that the severe MAC group had a mean age of 78 years, with 44.7% men. Baseline MR was grade III or IV in 89.0% of this cohort. Over 90% had primary MR. The median MAC volume was approximately 4,000 mm³ (reaching a high of 38,000 mm³). STS-PROM was 7.1% on average.

Tendyne TMVR was associated with 98.1% procedural survival and 94.2% technical success. MAC patients saw MR drop to grade 1 or less in all cases. Thourani also reported a drop in LVEF (55.0% to 52.2%), a drop in MV gradient (5.9 to 4.3 mmHg), and no change in LVOT gradient (2.1 to 2.4 mmHg).

Study authors noted that both SUMMIT groups felt better after TMVR, judging by New York Heart Association classification or Kansas City Cardiomyopathy Questionnaire scores.

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