title: [Evaluation of oral anticoagulation with rivaroxaban, in patients with new onset non valvular atrial fibrillation].
abstract: BACKGROUND
  Atrial fibrillation (AF) generates a hypercoagulable state with an increased thrombin generation and raised levels of thrombin-antithrombin complexes, which results in a high risk of stroke and thromboembolism.
  
  
  OBJECTIVE
  To evaluate the anticoagulant effect of rivaroxaban by anti-Xa factor activity and its correlation with thrombin-antithrombin complexes, thrombin generation and prothrombin time in patients newly diagnosed with non-valvular AF.
  
  
  METHODS
  Prospective study in patients with indication of anticoagulation. Demographic variables, cardiovascular risk factors, CHA2DS2-VASc and HAS-BLED scores were recorded. Blood samples were taken at baseline, at 3 and 24 hours after the administration of the drug and at 30 days. Rivaroxaban levels, anti-Xa activity, prothrombin time, thrombin generation and plasma levels of thrombin-antithrombin complexes were determined.
  
  
  RESULTS
  We studied 20 patients aged 76.3 ± 8.0 years (60% female) with a CHA2DS2-VASc score > 2 points. The anti-Xa factor activity correlated with rivaroxaban plasma levels at 3 hours (r = 0.61, p < 0.01), at 24 hours (r = 0.85, p < 0.01) and at 30 days (r = 0.99, p < 0.01), with prothrombin time at 3 hours (r = -0.86, p = 0.019) and at 30 days (r = -0.63, p = 0.02) and with a sustained decrease in thrombin generation at 30 days of follow-up (r = -0.74, p < 0.01). There was no correlation with thrombin-antithrombin complexes (r = -0.02, p = 0.83).
  
  
  CONCLUSIONS
  Rivaroxaban consistently inhibited the mild pro-coagulant state found in newly diagnosed non-valvular AF patients through the first 24 hours and this effect was maintained at 30 days. Plasma levels of the drug correlated with anti-Xa factor activity, thrombin generation and prothrombin time.
authors.affiliation: División de Enfermedades Cardiovasculares, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Víctor
authors.initials: V
authors.lastname: Neira
authors.affiliation: División de Enfermedades Cardiovasculares, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Ramón
authors.initials: R
authors.lastname: Corbalán
authors.affiliation: Departamento de Hematología y Oncología, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Jaime
authors.initials: J
authors.lastname: Pereira
authors.affiliation: Departamento de Hematología y Oncología, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Olga
authors.initials: O
authors.lastname: Panes
authors.affiliation: División de Enfermedades Cardiovasculares, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Bernardita
authors.initials: B
authors.lastname: Garayar
authors.affiliation: División de Enfermedades Cardiovasculares, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Andrés
authors.initials: A
authors.lastname: Aizman
authors.affiliation: División de Enfermedades Cardiovasculares, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Silvana
authors.initials: S
authors.lastname: Llevaneras
authors.affiliation: Departamento de Salud Pública, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Villarroel
mesh_terms: D000284:Administration, Oral; D000368:Aged; D000369:Aged, 80 and over; D000990:Antithrombin III / Q000187:drug effects*; D001281:Atrial Fibrillation / Q000097:blood*; D015951:Factor Xa / Q000187:drug effects* / Q000378:metabolism; D065427:Factor Xa Inhibitors / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D010447:Peptide Hydrolases / Q000187:drug effects*; D011446:Prospective Studies; D011517:Prothrombin Time; D000069552:Rivaroxaban / Q000494:pharmacology*; D013917:Thrombin / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
chemical_list: D065427:Factor Xa Inhibitors; C046193:antithrombin III-protease complex; D000990:Antithrombin III; D000069552:Rivaroxaban; D010447:Peptide Hydrolases; D013917:Thrombin; D015951:Factor Xa