Fourth-Gen Transcatheter Mitral Valve Shows Clinical, Procedural Improvements

Ted Bosworth

September 19, 2022

The design improvements introduced in the fourth-generation device for transcatheter mitral valve repair, called the MitraClip G4 (Abbott), appears to yield better outcomes than previous iterations, according to a multinational postapproval study with more than 1,000 patients.

Not least, the 1.3% all-cause mortality at 30 days in this series, called EXPAND G4, "is the lowest that has been reported to date," reported Ralph Stephan von Bardeleben, MD, at the Transcatheter Cardiovascular Therapeutics annual meeting, sponsored by the Cardiovascular Research Foundation.

The evidence of relative advantages was based on comparisons with historical data and a similar study of the previous-generation device. That previous study, called EXPAND, evaluated the MitraClip NTR and ETR systems.

Device Times Shorter With New Device

"There were shorter device times with MitraClip G4," said von Bardeleben, referring to a more than 10-minute advantage over the previous generation device (35 minutes in EXPAND G4 vs. 46 min in EXPAND). Although the reduction in overall median procedure time was more modest (77 vs. 80 minutes), von Bardeleben said these are "the shortest device and procedural times reported to date."

He also reported what appeared to be incremental advantages across multiple other endpoints, such as procedural success (96.2% vs. 95.8%) and a reduction in the mean clip rate (1.4 vs. 1.5).

Compared with historical outcomes with other devices employed in transcatheter edge-to-edge repair (TEER) of mitral valves, von Bardeleben contended that the results support the premise that the MitraClip G4 system is a meaningful advance by incorporating such features as an expanded choice of clip sizes, a greater coaptation area, and a more advanced gripper actuation for leaflet grasping.

Over 90% Achieve MR 1+

Not least, it appears to increase the proportion of patients who achieve a mitral regurgitation grade of 1+ (MR1+) or lower, which is increasingly recognized as the goal of TEER, said von Bardeleben, head of the Centre of Structure Heart Disease Interventions, Heart Valve Centre, Mainz, Germany.

He said the rates of 91% achieving MR1+ or less and 98% achieved 2+ or lower compare favorably with most other series and exceeds levels achieved with surgery.

Von Bardeleben also contended that, because of its design features, the MitraClip G4 "expands the spectrum of TEER-suitable patients." He noted that 5% of the patients in this real-world series had a high risk of stenosis owing to such issues as severe annular or leaflet calcification and another 5% had factors that would predict inadequate MR reduction, such as Barlow's disease, bi-leaflet prolapse, and severe leaflet degeneration.

The 1,164 patients in EXPAND G4 were enrolled from sites in the United States, Europe, Canada, and Japan. For the key outcome measure of procedural success, echocardiograms were assessed by an independent core laboratory. Of the 1,164 patients enrolled, 1,044 (91%) had complete follow-up data at 30 days.

The procedural success rates were reflected in improvements in New York Heart Association (NYHA) functional classes and in the Kansas City Cardiomyopathy Questionnaire (KCCQ), a quality of life instrument. Prior to treatment, 69% were in NYHA class III or greater. Following treatment, the proportion was 17% ( < .0001). The 18-point improvement in the KCCQ was characterized by von Bardeleben as "both clinically and statistically significant [ < .0001]."

There were no strokes in this series, and the 30-day incidence of myocardial infarction was 0.2%. The proportion requiring cardiovascular surgery within 30 days was less than 1%. The rate of bleeding episodes, all of which were nonserious, was 7%.

The "EXPAND G4 study confirms the safety and effectiveness of the next generation MitraClip G4 system," according to von Bardeleben, and it did so "in a contemporary real-world setting."

Outcome Data Characterized as "Excellent"

Several invited panelists participating in a discussion following the presentation agreed.

"These results are excellent," said Raj Makkar, MD, associate director of interventional technologies at Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles. While he was impressed with the fact that only 2% missed the primary endpoint of MR 2+ or lower, he indicated that the 91% achieving MR 1+ or lower might be an even more apt signal that newer-generation devices are improving.

This was echoed by other panelists who appeared to form a general consensus over the premise that the target in TEER should no longer be MR 2+ for most patients.

"We should now be aiming for MR grade of 0-1," stated panelist Stephan Windecker, MD, chairman, department of cardiology, University of Bern (Switzerland). He indicated that this goal is increasingly reasonable given the advances in device design and greater operator experience.

Von Bardeleben reported financial relationships with Abbott Vascular, Edwards Lifesciences, Medtronic, and Neochord. Makkar reported financial relationships with Abbott Vascular, Cordis, Edwards Lifesciences, and Medtronic. Windecker reported financial relationships with more than 30 pharmaceutical companies, including Abbott Vascular, which manufactures MitraClip G4.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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