title: Influence of the On-X mechanical prosthesis on intermediate-term major thromboembolism and hemorrhage: a prospective multicenter study.
abstract: OBJECTIVE
  Long-term thromboembolic and hemorrhagic outcomes after mechanical valve replacement have been well described; however, few studies have described these outcomes after valve replacement with the On-X mechanical prosthesis (On-X Life Technologies, Inc, Austin, Tex).
  
  
  METHODS
  Between 2003 and 2008, 737 patients underwent either aortic valve replacement (n = 400), mitral valve replacement (n = 282), or double-valve replacement (n = 55). Longitudinal performance, freedom evaluation, and risk analysis were assessed with regard to major thromboembolism and hemorrhage. Risk modeling was performed with 16 variables inclusive of age, atrial fibrillation, concomitant coronary artery bypass grafting, New York Heart Association class, and ventricular dysfunction.
  
  
  RESULTS
  Early mortality was 2.5% (n = 10) for aortic valve replacement and 3.2% (n = 9) for mitral valve replacement. Late mortality for aortic valve replacement was 4.8% per patient-year and 6.0% per patient-year for mitral valve replacement. Five-year freedom from major thromboembolism was 96.5% ± 1.2% for aortic valve replacement and 97.7% ± 0.9% for mitral valve replacement. Five-year freedom from hemorrhage was 93.6% ± 1.8% for aortic valve replacement and 95.7% ± 1.5% for mitral valve replacement. Concomitant coronary artery bypass grafting was predictive of major thromboembolism after aortic valve replacement (hazard ratio, 5.3; P = .02) and antithrombotic hemorrhage after mitral valve replacement (hazard ratio, 4.7; P = .03). No other independent predictors of major thromboembolism or hemorrhage were identified. One thrombosed mitral prosthesis was observed after deliberate discontinuation of anticoagulation. The major thromboembolic events occurred with variation of international normalized ratio levels inclusive of subtherapeutic levels. The majority of hemorrhagic events occurred with high international normalized ratio levels.
  
  
  CONCLUSIONS
  The On-X mechanical prosthesis provides favorable intermediate-term results with regard to major thromboembolism and hemorrhage.
authors.affiliation: Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Chan
authors.forename: W R Eric
authors.initials: WR
authors.lastname: Jamieson
authors.forename: B-Khanh
authors.initials: BK
authors.lastname: Lam
authors.forename: Marc
authors.initials: M
authors.lastname: Ruel
authors.forename: Hilton
authors.initials: H
authors.lastname: Ling
authors.forename: Guy
authors.initials: G
authors.lastname: Fradet
authors.forename: Thierry G
authors.initials: TG
authors.lastname: Mesana
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000601:surgery*; D002170:Canada; D016009:Chi-Square Distribution; D005260:Female; D005343:Fibrinolytic Agents / Q000009:adverse effects*; D006349:Heart Valve Diseases / Q000401:mortality / Q000601:surgery*; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects* / Q000295:instrumentation* / Q000401:mortality; D006470:Hemorrhage / Q000097:blood / Q000139:chemically induced* / Q000401:mortality; D006801:Humans; D019934:International Normalized Ratio; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011474:Prosthesis Design; D018570:Risk Assessment; D012307:Risk Factors; D013923:Thromboembolism / Q000097:blood / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D005343:Fibrinolytic Agents