title: Transcatheter mitral valve-in-valve implantation:  current experience and review of literature.
abstract: OBJECTIVE
  Transcatheter mitral valve-in-valve (MVIV) implantation is an emerging technique for reoperative mitral valve replacement in high-risk patients. Clear guidelines on the use of transcatheter MVIV implantation are yet to be determined. In this review, we report our own experience as well as the recent available literature on this procedure.
  
  
  RESULTS
  Since 2010, four case series of three or more patients have been reported with a total number of 23 patients. We also include unpublished data of 13 additional patients, who recently had MVIV implantation at our institution. Mean age was 78.45 ± 9.2 years with a median follow-up ranging from 70 to 357 days. Mean The Society of Thoracic Surgeons (STS) score was 14.1   ± 7.1%. All patients were in New York Heart Association (NYHA) class III or IV. Thirty days mortality was 7.5% (n = 3) and late mortality was 10% (n = 4). All patients had improvement in postoperative NYHA class to I/II following MVIV implantation. The mitral regurgitation grade was reduced from 3+ or 4+ preoperatively to a grade of 0 or 1 postoperatively. There was no structural valve deterioration reported in the follow-up period in any of the studies.
  
  
  CONCLUSIONS
  The available literature supports the use of transcatheter MVIV implantation in selected high-risk patients with favorable results. Although there are no available long-term data on the procedure, the early and mid-term outcomes are excellent with no evidence of structural valve deterioration in the available follow-up period.
authors.affiliation: St Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada. acheung@providencehealth.bc.ca
authors.forename: Anson
authors.initials: A
authors.lastname: Cheung
authors.forename: Ala
authors.initials: A
authors.lastname: Al-Lawati
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D063126:Balloon Valvuloplasty; D001705:Bioprosthesis; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D006801:Humans; D008297:Male; D008943:Mitral Valve / Q000601:surgery; D011474:Prosthesis Design; D012086:Reoperation; D013908:Thoracotomy; D016896:Treatment Outcome