title: Transcatheter aortic valve implantation: assessing the learning curve.
abstract: OBJECTIVE
  The aim of this study was to assess the learning curve for the implantation of the percutaneous aortic valve via the transfemoral route.
  
  
  BACKGROUND
  Transcutaneous aortic valve insertion is a fundamentally new procedure for the treatment of aortic valve stenosis. The number of cases needed to gain proficiency with concomitant ease and familiarity (i.e., the "learning curve") with the procedure is unknown.
  
  
  METHODS
  We performed a retrospective analysis of the first 44 consecutive patients who underwent transcatheter aortic valve implantation as part of the PARTNER (Placement of Aortic Transcatheter Valves) trial at our institution between November 2008 and May 2011.
  
  
  RESULTS
  The median age of the patients was 83 years (interquartile range: 77 to 87 years) and a median Society of Thoracic Surgery risk score of 9.6. Pre-procedural assessment of the aortic valve revealed a mean gradient of 53.5 mm Hg, mean aortic valve area of 0.7 mm(2), and a median ejection fraction of 59.5%. Patients were divided into tertiles based on sequence. Significant decreases in median contrast volume (180 to 160 to 130 ml, p = 0.003), valvuloplasty to valve deployment time (12.0 to 11.6 to 7.0 min, p < 0.001) and fluoroscopy times, from 26.1 to 17.2 and 14.3 min occurred from tertiles 1 to 3, p < 0.001. Significant decreases in radiation doses were also seen across the 3 tertiles, p < 0.001. The 30-day mortality for the entire cohort was 11%.
  
  
  CONCLUSIONS
  Experience accumulated over 44 transfemoral aortic valve implantations led to significant decreases in procedural times, radiation, and contrast volumes. Our data show increasing proficiency with evidence of plateau after the first 30 cases. More studies are needed to confirm these findings.
authors.affiliation: Division of Cardiovascular Diseases and Department of Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA.
authors.forename: Oluseun O
authors.initials: OO
authors.lastname: Alli
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Booker
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Lennon
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Greason
authors.forename: Charanjit S
authors.initials: CS
authors.lastname: Rihal
authors.forename: David R
authors.initials: DR
authors.lastname: Holmes
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000473:pathology*; D002404:Catheterization / Q000295:instrumentation* / Q000379:methods; D002983:Clinical Competence; D005260:Female; D006305:Health Status Indicators; D006349:Heart Valve Diseases / Q000628:therapy*; D019918:Heart Valve Prosthesis Implantation / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D059032:Learning Curve; D008297:Male; D012189:Retrospective Studies; D018570:Risk Assessment; D013223:Statistics as Topic; D013997:Time Factors; D016896:Treatment Outcome