title: Risks of fracture of Björk-Shiley 60 degree convexo-concave prosthetic heart valves: long-term cohort follow up in the UK, Netherlands and USA.
abstract: OBJECTIVE
  Approximately 82,000 Björk-Shiley convexo-concave (BSCC) 60 degree prosthetic heart valves were implanted in patients worldwide between 1979 and 1986. Outlet strut fractures (OSF) of some of the valves were first reported shortly after their introduction. Here, the determinants of OSF are examined, and the between-country variation and long-term risk are assessed.
  
  
  METHODS
  Cohorts of patients in the UK, Netherlands and USA with 15,770 BSCC 60 degree heart valves were followed up to 18 years for the occurrence of OSF.
  
  
  RESULTS
  Crude rates of OSF were highest in the UK (0.18% per year), intermediate in the Netherlands (0.13%), and lowest in the USA (0.06%), although risk factor adjustment reduced the inter-country differences. Furthermore, in the UK and Netherlands, OSF rates (particularly for mitral valves) declined with time since implantation, and between-country differences were considerably diminished 10 or more years post implantation. The risk of OSF decreased steadily with advancing patient age. Fracture rates were lower among women than men, and also varied significantly with valve size and position and OSF status of other valves in the same shoporder.
  
  
  CONCLUSIONS
  This long-term follow up of BSCC 60 degree heart valve patients indicates that risk factors for valve fracture are generally similar in the UK, Netherlands and USA. It also identifies a strong association between fracture risk and age, newly reveals gender-related differences, and shows that the risk of valve fracture persisted, albeit at a reduced rate, into the 1990s.
authors: International Epidemiology Institute, Rockville, MD, USA.
authors: W J
authors: WJ
authors: Blot
authors: R Z
authors: RZ
authors: Omar
authors: M
authors: M
authors: Kallewaard
authors: L S
authors: LS
authors: Morton
authors: J P
authors: JP
authors: Fryzek
authors: M A
authors: MA
authors: Ibrahim
authors: D
authors: D
authors: Acheson
authors: K M
authors: KM
authors: Taylor
authors: Y
authors: Y
authors: van der Graaf
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D019544:Equipment Failure Analysis / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000601:surgery*; D006350:Heart Valve Prosthesis / Q000706:statistics & numerical data*; D006351:Heart Valves / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011475:Prosthesis Failure; D012306:Risk; D012307:Risk Factors; D013997:Time Factors; D006113:United Kingdom; D014481:United States