title: In vitro comparison of dabigatran, unfractionated heparin, and low-molecular-weight heparin in preventing thrombus formation on mechanical heart valves.
abstract: BACKGROUND
  Lifelong oral anticoagulation (OAC) therapy is required for the prevention of thromboembolic events after implantation of an artificial heart valve. Thromboembolism and anticoagulant-related bleedings account for approximately 75% of all complications experienced by heart valve recipients (2-9% of patients per year). The present study investigated the efficacy of dabigatran, a new direct thrombin inhibitor for oral use, as compared to unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) in preventing thrombus formation on mechanical heart valves in vitro.
  
  
  METHODS
  Blood (230 ml) from healthy young male volunteers was anticoagulated either by dabigatran (1 micromol/l), UFH (150 IU), or LMWH (100 IU). Mechanical heart valve prostheses were placed in an in vitro thrombosis tester and exposed to the anticoagulated blood samples under continuous circulation at a rate of 75 beats per minute.
  
  
  RESULTS
  In whole blood with no anticoagulant, the apparatus completely clotted in 15-20 minutes. When blood was treated with dabigatran, the mean thrombus weight was 164+/-55 mg, in the UFH group 159+/-69 mg, and in the LMWH group 182+/-82 mg (p-value: 0.704). Electron microscopy showed no significant difference in thrombus formation in any group.
  
  
  CONCLUSIONS
  Dabigatran was as effective as UFH and LMWH in preventing thrombus formation on mechanical heart valves in our in vitro investigation. Thus, we hypothesize that dabigatran etexilate might potentially be a useful and competitive orally administered alternative to UFH and LMWH for recipients of alloplastic heart valve prostheses.
authors.affiliation: Department of Medicine III at the University Hospital Haale (Saale), Martin-Luther-University Halle-Wittenberg, Germany. maegdefessel@stanford.edu
authors.forename: Lars
authors.initials: L
authors.lastname: Maegdefessel
authors.forename: Torsten
authors.initials: T
authors.lastname: Linde
authors.forename: Franziska
authors.initials: F
authors.lastname: Krapiec
authors.forename: Kathrin
authors.initials: K
authors.lastname: Hamilton
authors.forename: Ulrich
authors.initials: U
authors.lastname: Steinseifer
authors.forename: Joanne
authors.initials: J
authors.lastname: van Ryn
authors.forename: Uwe
authors.initials: U
authors.lastname: Raaz
authors.forename: Michael
authors.initials: M
authors.lastname: Buerke
authors.forename: Karl
authors.initials: K
authors.lastname: Werdan
authors.forename: Axel
authors.initials: A
authors.lastname: Schlitt
mesh_terms: D000284:Administration, Oral; D000925:Anticoagulants / Q000008:administration & dosage / Q000494:pharmacology*; D001562:Benzimidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D001777:Blood Coagulation / Q000187:drug effects*; D000069604:Dabigatran; D005343:Fibrinolytic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D006493:Heparin / Q000008:administration & dosage / Q000494:pharmacology*; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D008297:Male; D011474:Prosthesis Design; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology*; D013927:Thrombosis / Q000097:blood / Q000209:etiology / Q000517:prevention & control*; D013997:Time Factors
chemical_list: D000925:Anticoagulants; D001562:Benzimidazoles; D005343:Fibrinolytic Agents; D006495:Heparin, Low-Molecular-Weight; D011725:Pyridines; D006493:Heparin; D000069604:Dabigatran