title: TRAP-induced platelet aggregation is enhanced in cardiovascular patients receiving dabigatran.
abstract: OBJECTIVE
  Novel (or non-vitamin K antagonist) oral anti-coagulants (NOACs) are antagonists of coagulation factors (F) Xa (rivaroxaban) or IIa (dabigatran), and their non-inferiority compared with vitamin K antagonists has been demonstrated in patients with non-valvular atrial fibrillation. However, it is still not fully understood if and how dabigatran and rivaroxaban impact platelet function. This observational study aimed to assess platelet function in patients receiving dabigatran or rivaroxaban.
  
  
  RESULTS
  This was a single centre, observational study quantifying platelet aggregation in 90 patients treated with NOACs by multiple electrode aggregometry. The thrombin receptor activating peptide (TRAP)-induced platelet aggregation was significantly higher in 35 patients receiving dabigatran (d) compared with control (c) patients (d 108±31 vs. c 85±30arbitrary units [AU]∗min, p<0.001). Patients receiving rivaroxaban (r) showed no differences compared with the control group (r 88±32 vs. c 85±30AU∗min, p=0.335). In intraindividual time courses of 16 patients, a significantly higher aggregation was found after the administration of dabigatran (before vs. after; 83±29 vs. 100±31AU∗min, p=0.009).
  
  
  CONCLUSIONS
  In this observational study, the TRAP-induced platelet aggregation was enhanced in cardiovascular patients receiving dabigatran. This might be explained by a change in the expression profile of thrombin receptors on the surface of platelets. Rivaroxaban had no influence on platelet aggregation.
authors.affiliation: Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany. Electronic address: Christoph.Olivier@universitaets-herzzentrum.de.
authors.forename: Christoph B
authors.initials: CB
authors.lastname: Olivier
authors.affiliation: Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Weik
authors.affiliation: Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Meyer
authors.affiliation: Center for Medical Biometry and Medical Informatics, Medical Center - University of Freiburg, Freiburg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Weber
authors.affiliation: Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.
authors.forename: Nathaly
authors.initials: N
authors.lastname: Anto-Michel
authors.affiliation: Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Diehl
authors.affiliation: Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Medical Center-University of Freiburg, Institute for Clinical Chemistry and Laboratory Medicine, Freiburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Geisen
authors.affiliation: Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bode
authors.affiliation: Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Moser
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000991:Antithrombins / Q000494:pharmacology / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D001792:Blood Platelets / Q000187:drug effects*; D000069604:Dabigatran / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D011655:Pulmonary Embolism / Q000188:drug therapy; D018179:Receptors, Thrombin / Q000378:metabolism*; D000069552:Rivaroxaban / Q000494:pharmacology / Q000627:therapeutic use*; D020246:Venous Thrombosis / Q000188:drug therapy
chemical_list: D000991:Antithrombins; D018179:Receptors, Thrombin; D000069552:Rivaroxaban; D000069604:Dabigatran
keywords: Aggregation; Dabigatran; Platelet; Rivaroxaban