title: Comparison of unfractionated heparin, low-molecular-weight heparin, low-dose and high-dose rivaroxaban in preventing thrombus formation on mechanical heart valves: results of an in vitro study.
abstract: Thromboembolism and bleeding after mechanical heart valve replacement are still unsolved problems, particularly for patients requiring anticoagulative bridging therapy. The aim of this study was to investigate whether rivaroxaban, a new oral selective and direct coagulation factor Xa inhibitor, is as effective as enoxaparin and unfractionated heparin (UFH) in preventing thrombus formation on mechanical heart valves using an in vitro system. Blood from healthy male donors was anticoagulated with either UFH, enoxaparin, rivaroxaban at 300 ng/ml, (n = 10 each), or rivaroxaban at 30 ng/ml (n = 3). Mechanical aortic valve prostheses were placed into the in vitro testing system THIA II and exposed to the anticoagulant blood mixtures at a pulsatile flow for 60 min. Overall thrombus weight, coagulation parameters, and electron microscopic features of thrombus formation on the valve surface were quantified as endpoints. The mean thrombus weights were 163 ± 64 mg for group 1 (UFH), 341 ± 63 mg for the group 2 (enoxaparin), 238 ± 83 mg for group 3 (rivaroxaban 300 ng/ml) and 1.739 ± 16 mg for group 4 (rivaroxaban 30 ng/ml). Whereas high-dosed rivaroxaban showed no significant differences compared to UFH or enoxaparin, low-dosed rivaroxaban generated a massive thrombus generation, thus differing significantly from all other treatment groups regarding the thrombus weight. We hypothesize that high-dose rivaroxaban is a competitive oral available alternative to UFH and LMWH's, that might be a worthwhile alternative for patients in need of anticoagulative bridging therapy. Prospective studies have to evaluate if rivaroxaban might even overcome the limitations of OAC in patients after implantation of artificial heart valves.
authors.affiliation: Department of Internal Medicine III, Martin Luther-University Halle-Wittenberg, Ernst-Grube-Str. 40, 06120 Halle, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Kaeberich
authors.forename: Iris
authors.initials: I
authors.lastname: Reindl
authors.forename: Uwe
authors.initials: U
authors.lastname: Raaz
authors.forename: Lars
authors.initials: L
authors.lastname: Maegdefessel
authors.forename: Alexander
authors.initials: A
authors.lastname: Vogt
authors.forename: Torsten
authors.initials: T
authors.lastname: Linde
authors.forename: Ulrich
authors.initials: U
authors.lastname: Steinseifer
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Perzborn
authors.forename: Baerbel
authors.initials: B
authors.lastname: Hauroeder
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: D000925:Anticoagulants; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D006493:Heparin / Q000494:pharmacology*; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008954:Models, Biological; D009025:Morpholines / Q000008:administration & dosage / Q000494:pharmacology*; D010477:Perfusion; D000069552:Rivaroxaban; D013876:Thiophenes / Q000008:administration & dosage / Q000494:pharmacology*; D013927:Thrombosis / Q000188:drug therapy / Q000209:etiology / Q000517:prevention & control*
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D009025:Morpholines; D013876:Thiophenes; D006493:Heparin; D000069552:Rivaroxaban