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BOSTON -- Contemporary practice had the fourth-generation MitraClip producing low short-term mortality and other good results even in mitral regurgitation (MR) patients previously deemed unsuitable for transcatheter edge-to-edge repair (TEER), according to a post-approval study.

In over 1,000 patients, MitraClip G4 was associated with 96.2% acute procedural success -- defined as survival to discharge with MR reduction to ≤2+ -- with 91% of people achieving MR ≤1+ and 98% MR ≤2+ in the EXPAND G4 study, reported Ralph Stephan von Bardeleben, MD, of Universitätsmedizin Heart Valve Center Mainz in Germany.

Notably, the 30-day all-cause death was an "extremely low" 1.3%, and other major adverse events remained at 1.0% or below, von Bardeleben said at the Transcatheter Cardiovascular Therapeutics (TCT) meeting hosted by the Cardiovascular Research Foundation.

He highlighted the wider spectrum of TEER-suitable patients based on the study: participants meeting usual unsuitability criteria reached 5% for the category of increased risk of stenosis (e.g., severe annular or leaflet calcification), 5% for increased risk of inadequate MR reduction (e.g., Barlow's disease, minimal leaflet tissue), and 28% for baseline moderate MR or less on independent echocardiographic core laboratory analysis (e.g., MR severity <3+).

Among all these subgroups, the proportion achieving MR 1+ or less was in the range of 87% to 94%, he stated.

The G4 added two wider cup sizes and an independent grasping feature to the usual MitraClip design. The latest-generation device was associated with a device time was 35 minutes and procedure time 77 minutes, the fastest to date for MitraClip, according to von Bardeleben.

He noted that the clip's independent grasping, employed as an upfront strategy in 5.5% of cases in the study, is particularly helpful where there is prolapse and excessive leaflet tissue to engage.

The increased procedural efficiency is also a testament to the likely improved operator experience, commented Michael Young, MD, of Dartmouth Hitchcock Medical Center in Lebanon, New Hampshire, at a TCT press conference.

Now left up for debate is how much residual MR is acceptable, Young said.

von Bardeleben clarified that residual moderate-severe MR was only 2% to 5% after MitraClip G4 therapy. He suggested that operators can expect to deal with clip failures by removing or replacing them in a small subset of patients.

For now, Robert Cubeddu, MD, of Naples Heart Institute in Florida, who was not involved in the current study, concluded that given the improved outcomes, the device time, and the technical success rate, the data on MitraClip G4 are "incredibly reassuring."

The EXPAND G4 results come on the heels of a from developer Abbott Vascular that the G4 and older MitraClips have occasionally been subject to clip lock malfunctions that result in intraprocedural MR recurrence. The manufacturer said it is updating materials processing to mitigate these events.

The present analysis included 1,164 people (mean age 77.5, 55.9% men) in the U.S., Europe, Canada, and Japan. Of those individuals, 1,044 had 30-day follow-up available for analysis.

Study enrollment was based on site-reported MR and allowed for the inclusion of acutely decompensated people. von Bardeleben noted that enrollment in Europe was subject to more relaxed MR severity requirement for MitraClip therapy in accordance with European guidelines.

The cohort had primary MR in 41.6% of cases. Baseline tricuspid regurgitation 3+ or 4+ was observed in 8.1%.

MitraClip TEER resulted in significant improvements in New York Heart Association functional class and Kansas City Cardiomyopathy Questionnaire scores at 30 days.

Medication changes were not captured in EXPAND G4, von Bardeleben acknowledged.

Longer-term follow-up is ongoing and planned for 5 years, he said, adding that by then, investigators may be able to sort out which anatomies are better suited to specific MR treatment devices.

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