title: Multicentered European study on safety and effectiveness of the On-X prosthetic heart valve: intermediate follow-up.
abstract: BACKGROUND
  This study was performed to determine the safety and effectiveness of the On-X valve, a novel mechanical valve substitute.
  
  
  METHODS
  Eleven centers participated in a European, multicentered, longitudinal, nonrandomized study of the On-X valve performance. Isolated aortic or mitral valve replacement with an On-X valve was studied in 301 patients. Aortic valve replacement was performed in 184 patients (average follow-up, 5.0 years), whereas mitral valve replacement was performed in 117 patients (average follow-up, 4.4 years).
  
  
  RESULTS
  In patients with aortic valve replacement, mean transvalvular pressure gradients ranged from 8.3 to 4.7 mm Hg and effective orifice areas from 1.5 to 2.7 cm2, for 19-mm through 25-mm valves, respectively. After mitral valve replacement, mean gradient was 4.2 mm Hg and effective orifice area by pressure half-time was 2.6 cm2 regardless of valve size. Hemolysis was low, with postoperative serum lactate dehydrogenase at 225 +/- 41 IU (mean +/- standard deviation) or 253 +/- 65 IU, after aortic valve replacement or mitral valve replacement, respectively (upper normal value, 250 IU). At 1 year or greater postoperatively, 91.6% of patients after aortic valve replacement and 84.6% after mitral valve replacement were in New York Heart Association functional class I or II. Adverse event rates in percent per patient-year after aortic valve replacement or mitral valve replacement were thromboembolism, 0.88 or 1.76; thrombosis, 0.11 or 0.20; bleeding, 0.77 or 1.96, respectively. Late mortality was 1.97% or 2.55%, respectively.
  
  
  CONCLUSIONS
  At the intermediate follow-up, the On-X valve exhibited improved hemodynamics, low hemolysis with in-range lactate dehydrogenase, and low adverse event rates, particularly in the aortic position.
authors.affiliation: Onassis Cardiac Surgery Center, Athens, Greece. palatianos@otenet.gr
authors.forename: George M
authors.initials: GM
authors.lastname: Palatianos
authors.forename: Axel M
authors.initials: AM
authors.lastname: Laczkovics
authors.forename: Paul
authors.initials: P
authors.lastname: Simon
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Pomar
authors.forename: Dietrich E
authors.initials: DE
authors.lastname: Birnbaum
authors.forename: Hans H
authors.initials: HH
authors.lastname: Greve
authors.forename: Axel
authors.initials: A
authors.lastname: Haverich
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000601:surgery; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects* / Q000401:mortality; D006461:Hemolysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery; D011446:Prospective Studies; D012449:Safety