• EXPAND G4: Newest MitraClip Devices Safe, Effective in Primary and Secondary MR

    BOSTON — Transcatheter edge-to-edge repair (TEER) with the newest-generation MitraClip G4 system demonstrated safety and effectiveness in both primary and secondary mitral regurgitation (MR), according to new study results.

    Ralph Stephan von Bardeleben, MD, of the University Medical Center of Mainz, Germany, presented these findings from the EXPAND G4 study Saturday at Transcatheter Cardiovascular Therapeutics (TCT) 2022 in Boston.

    The fourth-generation MitraClip G4 System (Abbott) builds on the previous third-generation system with two additional wider clip sizes, NTW and XTW. The post-approval study is designed to assess the safety and effectiveness of the MitraClip G4 System in a contemporary, global, real-world setting, and it is the first complete analysis of core lab-assessed 30-day outcomes from the entire study cohort of more than 1,000 subjects, von Bardeleben said.

    The prospective, multicenter, single-arm study enrolled 1,164 subjects with primary or secondary MR who received the MitraClip G4 system at 60 sites in the U.S., Europe, Canada and Japan.

    Follow-up was conducted at discharge and 30 days and will continue annually through 5 years.

    The key outcome measures are acute procedural success (defined as survival to discharge with MR reduction to grade 2+ or lower); major adverse events at 30 days; and MR severity, functional capacity assessed through the New York Heart Association (NYHA) classification system, and quality of life assessed through the Kansas City Cardiomyopathy Questionnaire (KCCQ).

    Of the 1,164 subjects enrolled, 1,141 were discharged (five withdrew consent, 10 died and eight did not undergo a discharge visit). At 30 days, 1,044 subjects were available (21 withdrew consent, 20 died and 56 did not undergo a 1-month visit), for a 91% follow-up rate.

    Of the original study subjects enrolled, 98% were implanted with a MitraClip G4 device (95% confidence interval [CI]: 97.1%, 98.7%). Acute procedural success was achieved in 96.2% (95% CI: 94.9%, 97.2%). The median device time was 35 minutes (interquartile range [IQR]: 21, 54 minutes), and the median procedure time was 77 minutes (IQR: 56, 104 minutes). The mean number of clips per patient was 1.4 ± 0.6.

    The procedural success rate was lower than that of the EXPAND study (98.9% [95% CI: 98.1%, 99.5%), but von Bardeleben noted that the 98% rate was still high and that the procedure time is the shortest reported to date, with a 24% reduction in device time compared to that of the EXPAND study (46 minutes [IQR: 30, 71 minutes). The EXPAND study used the third-generation MitraClip NTR and XTR devices.

    At 30 days, 91% of subjects had achieved an MR grade 1+ and 98% had an MR grade 2+; 83% of patients were at NYHA functional class I or II, a significant improvement from the 31% at baseline (p<0.0001); and the mean KCCQ score improved from 52 points at baseline to 70 at 30 days (absolute difference: +18 ± 25 points; paired t-test p-value <0.0001).

    Fifteen patients (1.3%) had died at 30 days, yielding an all-cause mortality rate of 1.3%, which von Bardeleben said is the lowest reported to date. There were also no reported strokes, 10 non-elective cardiovascular surgeries for device-related complications (0.9%) and 12 single leaflet device attachment events (1%) at 30 days.

    The MitraClip G4 has also expanded the pool of patients to include some who were considered unsuitable for mitral TEER in a 2021 consensus document, von Bardeleben said. The analysis shows that 28% of the original study cohort had a moderate or less MR at baseline, 5% had a risk of stenosis (given a red flag in the document and defined as one of the following: severe annular calcification, severe leaflet calcification, prior mitral annuloplasty or mitral valve area <3.5 cm2), and 5% had a risk of inadequate MR reduction (given a yellow flag and defined as at least one of the following: presence of Barlow’s disease, bi-leaflet prolapse/flail, significant secondary jet, severe leaflet degeneration with large gaps, minimal leaflet tissue, or significant cleft or scallop).

    “The EXPAND G4 study confirms the safety and effectiveness of the next-generation G4 system in a real-world setting,” von Bardeleben said. “It demonstrates tailoring of the therapy to the individual mitral valve anatomy, a consistent MR reduction with extremely low adverse events, high procedural efficacy with a lower number of clips (only 1.4), and this expands the spectrum of the TEER-suitable patients in the formerly untreatable patients.”

    Image Credit: Jason Wermers/CRTonline.org

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