MitraClip Shines in Real-World, Core-Lab Data

PHOENIX -- Newer MitraClip devices reduced mitral regurgitation (MR) to no more than a trace for nearly all patients, regardless of anatomical complexity or presence of advanced heart failure, in a pooled analysis that combined data from the EXPAND and EXPAND G4 studies, resulting in one of the largest core lab-assessed datasets for MR.

In assessing the third- and fourth-generation MitraClip systems, 90% of patients had a reduction in MR to 1+ or less at 30 days, reported Matthew J. Price, MD, of the Scripps Clinic in La Jolla, California, at the annual TVT conference hosted by the Cardiovascular Research Foundation.

For those with primary MR, slightly fewer patients with complex anatomy had reduction of their MR to grade 1+ or less at 30 days (80% vs 90%, P=0.0002), but improvements in functional class and quality of life were similar to those without complex anatomy.

For secondary MR, reductions were also similar, regardless of severity of heart failure (90% advanced vs 88% less advanced, P=0.7). While advanced heart failure patients saw somewhat less improvement in New York Heart Association (NYHA) class than those with less advanced heart failure (70% vs 83% class I or II), their improvement in quality of life at 30 days was comparable.

"It was pretty surprising and impressive how good the outcomes with mitral regurgitation are currently," said session panelist Gorav Ailawadi, MD, of the University of Michigan in Ann Arbor.

He noted that prior data from the TVT registry for 2014 through 2020 suggested only about half of patients were getting an ideal result in terms of mild or moderate residual MR and a gradient less than 5 mm Hg.

Price suggested that the difference was in part due to the time period studied, with the third-generation MitraClip EXPAND registry data dating back to 2018 and the fourth-generation EXPAND G4 data having reached its primary completion date in 2022. "Different experiences, I think learning to treat the right patient may be part of it as well. And finally, we know with echos [echocardiography], having a core lab is incredibly important."

His study pooled patient-level data from the EXPAND and EXPAND G4 registries into the EXPANDed cohort -- with all the echocardiography core lab adjudicated, in contrast to the site-reported echo data in the TVT registry.

EXPANDed comprised a total of 2,205 patients who underwent MitraClip implantation, among whom 1,997 completed the 30-day follow-up assessment. Overall, 47% had primary MR.

Devices included the third-generation NTR and XTR devices and the fourth-generation NT, NTW, XT, and XTW MitraClip systems. Slightly less than half of the enrolled patients had a third-generation device versus a fourth-generation device.

The proportion of patients overall in NYHA class I or II improved from 27% to 82% at 30 days. Kansas City Cardiomyopathy Questionnaire (KCCQ) quality-of-life scores improved by 19 points on the 100-point scale over that period as well.

Results in primary or mixed etiology MR were compared in 852 patients who had at least MR 3+ at baseline. The 258 complex patients had to have at least one of the following characteristics: bi-leaflet flail or prolapse, calcification in landing zone, multiple jets, significant cleft or scallop, wide jet, primary jet outside A2P2, minimal leaflet tissue, severely degenerative leaflets, and small valve area, while 319 non-complex patients had none of these criteria.

The proportion of patients with NYHA I or II disease at 30 days was 85% in both complex and non-complex cases. KCCQ improvement averaged 20 points in the complex group and 18 points in the non-complex group (P=0.4).

The 966 patients with secondary MR of at least 3+ included 70 with advanced heart failure characterized by at least one of the following: left ventricular ejection fraction less than 20%, left ventricular end systolic dimension greater than 70 mm, and systolic pulmonary artery pressure over 70 mm Hg.

The 30-day KCCQ score improvement in advanced heart failure averaged 20 points, compared with 22 in the less advanced heart failure patients (P=0.7).

"The EXPANDed cohort paves the way for robust subgroup analyses following treatment with the MitraClip system," Price concluded, noting gradient data as an example.

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