Early Next-Gen MitraClip Results Impress, Raise Eyebrows

Patrice Wendling

June 07, 2019

PARIS — Two new studies show marked reductions in mitral regurgitation (MR), but also an uptick in single-leaflet device attachment (SLDA), in early experience with the latest iterations of the MitraClip (Abbott Vascular).

The EXPAND study provided 30-day outcomes in the first 500 patients treated at 60 sites in Europe and the United States with the third-generation MitraClip NTR and XTR systems, introduced in 2018. The NTR has the same clip size as the original MitraClip NT system, but with an improved delivery system. The XTR has 3 mm longer arms and grippers, designed to improve leaflet grasping, as well as a revamped delivery system.

Rates of clip implantation and acute procedural success were 99.2% and 94.0% in the all-comer population (mean age, 77.9 years), with primary, secondary or functional MR, or mixed MR. One clip was used in 54% of cases, two clips in 41%, and three or more in 5%.

At discharge, 96% of patients had MR grade 2+ or better, whereas they all were MR grade 3+ (45%) or grade 4+ (55%) at baseline. The percentage of patients in New York Heart Association (NYHA) class I or II also jumped from just 21% at baseline to 80% at 30 days.

At 30 days, there were 14 deaths (2.8%), two strokes (0.4%), and seven (1.4%) nonelective CV surgeries for device-related complications, according to results presented at the Congress of the European Association of Percutaneous Cardiovascular Intervention 2019.

There was one embolization (0.2%) and 17 SLDAs (3.4%), with 71% of SLDAs in patients with more complex "non-Everest II" anatomy, noted study author Jörg Hausleiter, MD, Klinikum der Universität München, Germany. Most SLDAs also occurred during the first five cases at any site, suggesting a learning curve with the latest iterations.

The data are preliminary, with complete echocardiographic core lab analysis and independent event adjudication planned for the full EXPAND population of more than 1000 patients, he noted.

These are "excellent results delivered at low procedural risk, so in the hands of physicians who get frequent access to this expensive technology, the results look good and durable," session comoderator David Hildick-Smith, MD, Brighton and Sussex University Hospitals, Brighton, United Kingdom, told theheart.org | Medscape Cardiology.

He noted that an SLDA is "always concerning because it means the device becomes ineffective" and that means to reduce this complication rate to the lowest rate possible will be very welcome.

"The main unanswered question is around the selection of the right patient," Hildick-Smith said. "MITRA-FR and COAPT show us some of the patients who don’t and do benefit, respectively, and this needs to be further examined to avoid indiscriminate use of this technology in patients who actually will not benefit from it."

Notably, the EXPAND steering committee made recommendations for device selection based on anatomical factors. It favors the XTR for patients with longer leaflets, A2-P2 positioning, large flail, and redundant leaflet and the NTR for those with short restricted leaflets, calcification of the annulus and leaflet, smaller MV area, and mitral valve commissures.

 

More Selective Use

During the next day of the congress, Fabien Praz, MD, University of Bern, Switzerland, reported data on the MitraClip XTR in 107 consecutive patients (mean age, 76 years) with symptomatic primary (37%), secondary (50%), or mixed (13%) MR treated at three European tertiary care centers.

Technical success was achieved in 93% of patients. The procedure was aborted without clip placement in only one patient (0.9%), whereas this rate was 9% in MITRA-FR and 5% in COAPT, the authors note in the study, published simultaneously online May 22 in JACC: Cardiovascular Interventions.

Nevertheless, the main reasons for procedural failure were acute SLDA associated with leaflet damage (n = 2) and leaflet tearing during grasping (n = 2). Two additional SLDAs occurred: one related to gripper line disruption and one occurring 24 hours after the procedure in a patient with noncommissural prolapse. Two of the four SLDAs and both leaflet tears required conversion to surgery.

"Although relatively infrequent, this may correspond to a new mechanism of acute failure, possibly related to grasping of more tissue and subsequent increased tension exerted on the valve leaflets," write Praz and his colleagues. "These results may motivate a more selective use of the new device in patients with fragile anatomies."

They suggest "particular care" be taken to avoid applying too much tension on the valve during grasping, to limit the number of grasping attempts, and to maintain the MitraClip below the mitral valve (MV) plane and prevent malrotation during grasping.

Further, "short leaflets (shorter than two-thirds of clip arm length), fragile and thin-appearing leaflets, as well as calcifications of the annulus and MV apparatus may be additional anatomic exclusion criteria," the authors said.

"There is little doubt that the introduction of the MitraClip XTR is a major step forward in the field of transcatheter edge-to-edge repair. However, the findings of the current study indicate that this powerful device is not a 'one fits all' device, and that vigilance is warranted in its selection and use," .Mohamad Alkhouli, MD, West Virginia University, Morgantown, writes in an accompanying editorial.

In terms of efficacy, the degree of MR reduction with the XTR device is "arguably better" than that achieved in the EVEREST II trial and in early commercial experience, he noted. The TRAMI registry, as well as COAPT and MITRA-FR, however, reported ≤1+ residual MR in more than 75% of patients.

Among the 102 patients discharged alive without MV surgery in the present study, 93% had MR grade 2+ or better and 77% MR grade 1+ or better.

Finally, contrary to expectations, use of the XTR device did not appear to reduce the number of patients treated with more than one clip (43%), nor did it result in a higher transvalvular gradient at discharge (mean, 3.5 mm Hg) than reported in registries using the first-generation MitraClip.

Hausleiter reports receiving speaker honoraria and research support from Abbott Vascular and Edwards Lifesciences. Praz reports being a consultant for Edwards Lifesciences. Hildick-Smith and Alkhouli report no relevant relationships.

Congress of the European Association of Percutaneous Cardiovascular Interventions (EuroPCR) 2019. Presented May 21, 2019.

J Coll Cardiol Interv. Published online May 22, 2019. Abstract, Editorial

Follow Patrice Wendling on Twitter: @pwendl. For more from theheart.org  | Medscape Cardiology, join us on Twitter and Facebook.

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