title: Impact of wait times on the effectiveness of transcatheter aortic valve replacement in severe aortic valve disease: a discrete event simulation model.
abstract: BACKGROUND
  There is increasing demand for transcatheter aortic valve replacement (TAVR) as the primary treatment option for patients with severe aortic stenosis who are high-risk surgical candidates or inoperable. We used mathematical simulation models to estimate the hypothetical effectiveness of TAVR with increasing wait times.
  
  
  METHODS
  We applied discrete event modelling, using data from the Placement of Aortic Transcatheter Valves (PARTNER) trials. We compared TAVR with medical therapy in the inoperable cohort, and compared TAVR to conventional aortic valve surgery in the high-risk cohort. One-year mortality and wait-time deaths were calculated in different scenarios by varying TAVR wait times from 10 days to 180 days, while maintaining a constant wait time for surgery at a mean of 15.6 days.
  
  
  RESULTS
  In the inoperable cohort, the 1-year mortality for medical therapy was 50%. When the TAVR wait time was 10 days, the TAVR wait-time mortality was 1.9% with a 1-year mortality of 31.5%. TAVR wait-time deaths increased to 28.9% with a 180-day wait, with a 1-year mortality of 41.4%. In the high-risk cohort, the wait-time deaths and 1-year mortality for the surgical patients were 2.5% and 27%, respectively. The TAVR wait-time deaths increased from 2.2% with a 10-day wait to 22.4% with a 180-day wait, and a corresponding increase in 1-year mortality from 24.5% to 32.6%. Mortality with TAVR exceeded surgery when TAVR wait times exceeded 60 days.
  
  
  CONCLUSIONS
  Modest increases in TAVR wait times have a substantial effect on the effectiveness of TAVR in inoperable patients and high-risk surgical candidates.
authors.affiliation: Schulich Heart Centre, Division of Cardiology and Cardiac Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada. Electronic address: harindra.wijeysundera@sunnybrook.ca.
authors.forename: Harindra C
authors.initials: HC
authors.lastname: Wijeysundera
authors.affiliation: Toronto Health Economics and Technology Assessment (THETA) Collaborative, University of Toronto, Toronto, Ontario, Canada.
authors.forename: William W L
authors.initials: WW
authors.lastname: Wong
authors.affiliation: Schulich Heart Centre, Division of Cardiology and Cardiac Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Bennell
authors.affiliation: Schulich Heart Centre, Division of Cardiology and Cardiac Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Fremes
authors.affiliation: Schulich Heart Centre, Division of Cardiology and Cardiac Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sam
authors.initials: S
authors.lastname: Radhakrishnan
authors.affiliation: Division of Cardiac Surgery, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Peterson
authors.affiliation: Schulich Heart Centre, Division of Cardiology and Cardiac Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; Institute for Clinical Evaluative Sciences (ICES), Toronto, Ontario, Canada.
authors.forename: Dennis T
authors.initials: DT
authors.lastname: Ko
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000601:surgery*; D003663:Decision Trees; D005260:Female; D006349:Heart Valve Diseases / Q000601:surgery*; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects* / Q000379:methods; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D017063:Outcome Assessment, Health Care; D014850:Waiting Lists