title: Aniticoagulation in patients following prosthetic heart valve replacement.
abstract: OBJECTIVE
  To identify optimum international normalized ratio (INR) levels and required warfarin doses and anticoagulation-related complications in patients following mechanical prosthetic valve replacement.
  
  
  METHODS
  Five hundred and seven patients were prospectively followed up for 10 years (2008.5 patient-years). Anticoagulation-related complications were classified into hemorrhage and thromboembolism.
  
  
  RESULTS
  Two hundred and ninety-two (57.6%) were males and 215 (42.4%) were females with a mean age of 29.5 +/- 11.32 years. A total of 268 (52.9%) patients had mitral, 96 (18.9%) had aortic and mitral, and 76 (15%) had aortic valve replacement (AVR). Valves implanted totaled 345 (68%) ball and cage, 126 (24.9%) bileaflet, and 36 (7.1%) single disc. There were 10,669 total visits, with mean INR 2.6 +/- 0.59 and mean warfarin 5.17 +/- 1.6 mg. Sixty-four (3.2% per patient-years) events occurred during follow-up, of which 23 (1.13% per patient-years) events were due to thromboembolism and 41 (2.04% per patient-years) to bleeding. Atrial fibrillation occurred in 12 (52.4%) patients having thromboembolic events and in 24 (58.5%) suffering from bleeding complications. Among thromboembolic events, valve thrombosis occurred in 9 patients (0.44% per patient-years) and cerebrovascular accidents (CVAs) in 14 (0.69% per patient-years). Atrial fibrillation was present in 7 (77.8%) patients in the valve thrombosis group and in 5 (35.7%) in the CVA group. Of 41 bleeding events, 8 (0.39% per patient-years) were minor episodes, 20 (0.99% per patient-years) were major episodes, and severe hemorrhage occurred in 5 (0.34% per patient-years). Intracranial hemorrhage leading to CVA was seen in 8 patients (0.34% per patient-years). There were 22 (1.1% per patient-years) fatal hemorrhages and 15 (0.74% per patient-years) fatal thromboembolic events. In-hospital mortality was 25 (4.9%), and 62 (12.2%) were late deaths; of these, 37 (7.3%) were anticoagulation related.
  
  
  CONCLUSIONS
  Anticoagulation for mechanical heart valve replacement can be managed with INR levels of 2-2.5 with acceptable hemorrhagic and thromboembolic events.
authors.affiliation: Department of Cardiac Surgery, Punjab Institute of Cardiology, Lahore, Pakistan.
authors.forename: Raja Parvez
authors.initials: RP
authors.lastname: Akhtar
authors.forename: Abdul Rehman
authors.initials: AR
authors.lastname: Abid
authors.forename: Hasnain
authors.initials: H
authors.lastname: Zafar
authors.forename: Jawad Sajid
authors.initials: JS
authors.lastname: Khan
mesh_terms: D000293:Adolescent; D000328:Adult; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000209:etiology; D001777:Blood Coagulation / Q000187:drug effects*; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects* / Q000295:instrumentation; D006470:Hemorrhage / Q000097:blood / Q000139:chemically induced* / Q000401:mortality; D017052:Hospital Mortality; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D010154:Pakistan / Q000453:epidemiology; D011446:Prospective Studies; D011474:Prosthesis Design; D018570:Risk Assessment; D020521:Stroke / Q000097:blood / Q000209:etiology / Q000517:prevention & control; D013923:Thromboembolism / Q000097:blood / Q000209:etiology / Q000401:mortality / Q000517:prevention & control*; D013927:Thrombosis / Q000097:blood / Q000209:etiology / Q000517:prevention & control; D013997:Time Factors; D016896:Treatment Outcome; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D000925:Anticoagulants; D014859:Warfarin