Percutaneous Transcatheter Mitral Valve Replacement: First-in-Human Experience With a New Transseptal System.

Background: Severe mitral regurgitation (MR) conveys significant morbidity and mortality, and surgical repair or replacement may not be a desirable option.

Objectives: The purpose of this study was to evaluate the feasibility of a percutaneous transseptal transcatheter mitral valve replacement (TMVR) system.

Methods: This first-in-human study was conducted between August 2017 and August 2018. The system comprises a nitinol dock, which encircles the chordae tendineae, and a balloon-expandable transcatheter heart valve. The dock and transcatheter heart valve form an ensemble, with the native mitral valve leaflets secured in between, thereby abolishing MR. Key inclusion criteria were severe symptomatic MR and high surgical risk; exclusion criteria included left ventricular ejection fraction <30% or screening suggesting unfavorable anatomy. The primary endpoint was technical success as defined by Mitral Valve Academic Research Consortium (MVARC) criteria at completion of the index procedure. The secondary endpoint was freedom from mortality, stroke, and device dysfunction (MR grade >1, mitral gradient >6 mm Hg, left ventricular outflow tract gradient >20 mm Hg) at 30 days.

Results: Ten patients with severe MR of various etiologies (4 degenerative, 4 functional, and 2 mixed) were treated. The device was successfully implanted and the primary endpoint was achieved in 9 of 10 patients (90%). By transesophageal echocardiography, total MR was reduced to ≤ trivial in all implanted patients, and mean transmitral gradient was 2.3 ± 1.4 mm Hg. A pericardial effusion occurred in 1 patient: pericardiocentesis was performed, and the device was not implanted. Median length of hospital stay was 1.5 days. At 30 days, there was no stroke, myocardial infarction, rehospitalization, left ventricular outflow tract obstruction, device migration, embolization, or conversion to mitral surgery. One patient had recurrent regurgitation due to a paravalvular leak, treated with a closure device. All other treated patients had ≤1+ MR. No patients died.

Conclusions: Percutaneous transvenous transseptal TMVR is feasible and safe in patients with severe MR who are at high risk for mitral valve surgery. Further evaluation is warranted.