Transcatheter Transseptal Mitral Valve-in-Valve Replacement: An Early Australian Case Series and Literature Review.

Background: Transcatheter mitral valve implantation for degenerated bioprostheses has recently emerged as an alternative to redo mitral valve surgery, particularly in patients at high risk for reoperative cardiac surgery. We sought to examine our early experience of transcatheter transseptal mitral valve-in-valve procedures.

Methods: Prospectively collected data was retrospectively reviewed in patients undergoing transcatheter transseptal mitral valve-in-valve implantation using the Edwards Sapien 3 balloon expandable bioprosthesis (Edwards Lifesciences, Irvine, CA, USA).

Results: Seven (7) patients underwent the procedure between December 2017 and November 2018. Three (3) patients were young Indigenous Australians (age range 33-41years) who were not suitable for mechanical prostheses; four patients were elderly (age range 82-92 years) and considered high risk for reoperative surgery. The median (maximum, minimum) EuroSCORE II of the group was 7.32 (4.81, 19.89). Procedural success was obtained in six of the seven patients; these six patients had no significant complications and had a median hospital stay of 3 days. In one patient, the device displaced towards the left ventricle on inflation, resulting in left ventricular outflow tract obstruction and haemodynamic instability. Urgent redo mitral valve surgery and explantation of the transcatheter prosthesis was undertaken, however, this patient died postoperatively of multi-organ failure. Of the successfully deployed valves, the median (maximum, minimum) gradient across the new mitral prosthesis was 5.5 mmHg (4, 7) and only one patient had mild mitral regurgitation, all others had no or trivial regurgitation. At 30 days, these six patients are well and all are in New York Heart Association (NYHA) Class I.

Conclusions: Our early experience with transcatheter transseptal mitral valve-in-valve implantation demonstrates this procedure to be feasible in our institution with acceptable early results. Further follow-up is necessary to determine the longevity of valves implanted in this manner, especially in the younger population.