title: Aortic valve replacement: is valve size important?
abstract: OBJECTIVE
  We sought to determine whether aortic prosthesis size adversely influences survival after aortic valve replacement.
  
  
  METHODS
  A total of 892 adults receiving a mechanical (n = 346), pericardial (n = 463), or allograft (n = 83) valve for aortic stenosis were observed for up to 20 years (mean, 5.0 +/- 3.9 years) after primary isolated aortic valve replacement. We used multivariable propensity scores to adjust for valve selection factors, multivariable hazard function analyses to identify risk factors for all-cause mortality, and bootstrap resampling to quantify the reliability of the results.
  
  
  RESULTS
  Twenty-five percent of patients had indexed internal orifice areas of less than 1.5 cm(2)/m(2) and more than 2 SDs (Z-value) below predicted normal aortic valve size. Mechanical valve orifices were smaller (1.3 +/- 0. 29 cm(2)/m(2), Z = -2.2 +/- 1.16) than pericardial (1.9 +/- 0.36 cm(2)/m(2), Z = -0.40 +/- 1.01) or allograft valves (2.1 +/- 0.50, Z = 0.24 +/- 1.17). The overall survival was 98%, 96%, 86%, 69%, and 49% at 30 days and 1, 5, 10, and 15 years postoperatively. Univariably, survival was weakly and inversely related to manufacturer valve size (P =.16) and internal orifice diameter (P =. 2) but completely unrelated to indexed valve area (P =.6) or Z-value (P =.8). These, and univariable differences among valve types (P =. 004), were accounted for by different prevalences in patient risk factors and not by valve size or type per se. Bootstrap resampling indicated that these findings had a less than 15% chance of being incorrect.
  
  
  CONCLUSIONS
  Survival after aortic valve replacement is strongly related to patient risk factors but appears not to be adversely affected by moderate patient-prosthesis mismatch (down to about 4 SDs below normal). Aortic root enlargement to accommodate a large prosthesis may be required in few situations.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery and the Department of Biostatistics and Epidemiology, The Cleveland Clinic Foundation, Cleveland, Ohio, USA.
authors.forename: B
authors.initials: B
authors.lastname: Medalion
authors.forename: E H
authors.initials: EH
authors.lastname: Blackstone
authors.forename: B W
authors.initials: BW
authors.lastname: Lytle
authors.forename: J
authors.initials: J
authors.lastname: White
authors.forename: J H
authors.initials: JH
authors.lastname: Arnold
authors.forename: D M
authors.initials: DM
authors.lastname: Cosgrove
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001021:Aortic Valve / Q000601:surgery / Q000637:transplantation; D001024:Aortic Valve Stenosis / Q000401:mortality / Q000601:surgery*; D001672:Biocompatible Materials / Q000592:standards; D001705:Bioprosthesis / Q000592:standards; D005260:Female; D006350:Heart Valve Prosthesis / Q000592:standards*; D019918:Heart Valve Prosthesis Implantation / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D014184:Transplantation, Homologous; D016896:Treatment Outcome
chemical_list: D001672:Biocompatible Materials