title: Early prosthetic valve degeneration with Mitroflow aortic valves: determination of incidence and risk factors†.
abstract: OBJECTIVE
  We describe a cluster of early valve degeneration (EVD) in a series of 281 Mitroflow valves implanted during 1999-2013. Patients with EVD were identified as having symptomatic stenosis or regurgitation within 6 years of implantation leading to reoperation.
  
  
  METHODS
  Freedom from reoperation was estimated by Kaplan-Meier actuarial analysis. Patient and valve characteristics in the EVD group were compared with those without using univariate and Cox proportional hazard multivariate regression analysis.
  
  
  RESULTS
  The rate of actuarial freedom from reoperation was 97% at 6 years and 92.5% at 10 years. The linearized rate of reoperation was 0.7% per patient-year. Ten patients required repeat surgery for EVD. Reoperation occurred from 2 years of implantation in patients with a mean age of 60, compared with 70 in those without EVD. Causes of explantation were stenosis (8), regurgitation (1) and mixed disease (1). The age was the only significant predictor of early degeneration; P = 0.03, hazard ratio = 2.89. Other factors analysed were atrial fibrillation, hypertension, chronic obstructive pulmonary disease, stroke, diabetes, preoperative angina, poor left ventricular function, renal dysfunction and extracardiac arteriopathy. There were no significant postoperative complications or operative mortality in those patients undergoing repeat surgery.
  
  
  CONCLUSIONS
  There is an unexplained incidence (3.6%) of EVD resulting in explantation in some patients at 2 years after surgery. Mitroflow valves may not be suited to a younger age population.
authors.affiliation: Trent Cardiac Centre, Nottingham City Hospital, Nottingham, UK vijayjoshi@doctors.net.uk.
authors.forename: Vijay
authors.initials: V
authors.lastname: Joshi
authors.affiliation: Trent Cardiac Centre, Nottingham City Hospital, Nottingham, UK.
authors.forename: Kaye
authors.initials: K
authors.lastname: Prosser
authors.affiliation: Trent Cardiac Centre, Nottingham City Hospital, Nottingham, UK.
authors.forename: David
authors.initials: D
authors.lastname: Richens
mesh_terms: D000367:Age Factors; D000368:Aged; D001021:Aortic Valve / Q000503:physiopathology / Q000601:surgery*; D001022:Aortic Valve Insufficiency / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery; D001024:Aortic Valve Stenosis / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery; D016009:Chi-Square Distribution; D004739:England; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D018579:Patient Selection; D016016:Proportional Hazards Models; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
keywords: Aortic valve replacement; Bioprosthetic valves; Structural valve degeneration