title: Mechanical heart valves: are two leaflets better than one?
abstract: OBJECTIVE
  We sought to compare the long-term clinical outcomes of patients who underwent isolated aortic valve replacement with single-disc and bileaflet mechanical heart valves.
  
  
  METHODS
  From May 1975 through October 2001, 590 single-disc valves (7 models) were used for isolated valve replacement, and from November 1980 through July 2002, 1283 bileaflet valves (10 models) were used for isolated valve replacement. Detailed follow-up was performed to a maximum of 27.4 and 21.9 years with a total of 6872 and 5811 patient-years for single-disc valves and bileaflet valves, respectively. Survival and valve-related events were analyzed.
  
  
  RESULTS
  Single-disc valves were mainly implanted from 1975 through 1995, whereas bileaflet valves were mainly implanted from 1987 through 2002; thus the years of concurrent use were 1987 through 1995. The bileaflet valve had a significantly lower explantation rate, whereas the single-disc valve had a significantly lower thromboembolism rate. No significant differences were detected in early mortality, long-term survival, and other valve-related complications. When limiting the comparison to the concurrent period of 1987 through 1995, no significant difference was detected in survival or in any valve-related complication.
  
  
  CONCLUSIONS
  Single-disc and bileaflet valves provide similar clinical performance. The predominant use of bileaflet valves is not based on clinical outcomes.
authors.affiliation: Medical Data Research, Providence Health System, Portland, OR 97225, USA. yingxing.wu@providence.org
authors.forename: YingXing
authors.initials: Y
authors.lastname: Wu
authors.forename: Rosario
authors.initials: R
authors.lastname: Gregorio
authors.forename: Attilio
authors.initials: A
authors.lastname: Renzulli
authors.forename: Francesco
authors.initials: F
authors.lastname: Onorati
authors.forename: Marisa
authors.initials: M
authors.lastname: De Feo
authors.forename: Gary
authors.initials: G
authors.lastname: Grunkemeier
authors.forename: Maurizio
authors.initials: M
authors.lastname: Cotrufo
mesh_terms: D000328:Adult; D000368:Aged; D001021:Aortic Valve / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000401:mortality / Q000601:surgery; D006350:Heart Valve Prosthesis; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology / Q000401:mortality / Q000601:surgery; D011474:Prosthesis Design; D012086:Reoperation; D016019:Survival Analysis; D013995:Time; D013997:Time Factors; D016896:Treatment Outcome