title: Nonvalvular atrial fibrillation: evidence for a prothrombotic state.
abstract: OBJECTIVE
  To determine whether patients with nonvalvular atrial fibrillation (NVAF) have prothrombotic changes compared with patients in sinus rhythm.
  
  
  METHODS
  Cross-sectional study. Hemostatic function compared in NVAF patients without prior embolic event (transient ischemic attack or embolic stroke) and control subjects without prior thrombotic stroke, and in NVAF patients with prior embolic event and control subjects with prior thrombotic stroke.
  
  
  METHODS
  Internal medicine outpatient group practice and anticoagulation clinic in 2 teaching hospitals.
  
  
  METHODS
  A total of 75 NVAF patients (50 without and 25 with prior embolic event) and 42 control patients (31 without and 11 with prior thrombotic stroke) recruited concurrently over 18 months during 1990-91.
  
  
  METHODS
  Platelet count, prothrombin time (PT), partial thromboplastin time (PTT), and plasma levels of hemoglobin, fibrinogen, von Willebrand factor antigen, factor VIII, fibrin D-dimer, antithrombin III, protein C, protein S, fibrinopeptide A and prothrombin fragment F1+2. All statistical analyses were performed after adjustments for age and sex.
  
  
  RESULTS
  The NVAF patients without a prior embolic event had significantly higher mean hemoglobin and fibrinogen levels (p < 0.001 and p = 0.05, respectively) than the control subjects without prior thrombotic stroke. The 29 NVAF patients not taking warfarin (none had had an embolic event) had significantly lower mean protein C and protein S levels (p = 0.012 and p < 0.001, respectively) and a significantly higher fibrinopeptide A level (p = 0.03, after exclusion of outliers) than the control subjects without prior stroke. The NVAF patients with a prior embolic event had alterations in the hemostatic variables similar to those seen in the control patients with a prior thrombotic stroke. The latter had significantly higher fibrinogen, von Willebrand factor antigen and factor VIII levels (p = 0.04, 0.002 and 0.002, respectively) and significantly lower protein S levels (p = 0.02) than the control subjects without prior stroke.
  
  
  CONCLUSIONS
  NVAF patients without a history of an embolic event show evidence of a prothrombotic state compared with patients in sinus rhythm who have not had a thrombotic stroke. NVAF patients with a history of an embolic event show evidence of a prothrombotic state similar to that of patients in sinus rhythm who have had a thrombotic stroke. Prospective studies are needed to determine whether these abnormalities predict higher risk of stroke in individual NVAF patients.
authors.affiliation: Division of General Internal Medicine, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Que. susank@epid.jgh.mcgill.ca
authors.forename: S R
authors.initials: SR
authors.lastname: Kahn
authors.forename: S
authors.initials: S
authors.lastname: Solymoss
authors.forename: K M
authors.initials: KM
authors.lastname: Flegel
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D000990:Antithrombin III / Q000032:analysis; D001281:Atrial Fibrillation / Q000097:blood*; D003430:Cross-Sectional Studies; D005169:Factor VIII / Q000032:analysis; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D005340:Fibrinogen / Q000032:analysis; D005344:Fibrinopeptide A / Q000032:analysis; D006454:Hemoglobins / Q000032:analysis; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000150:complications; D002546:Ischemic Attack, Transient / Q000150:complications; D008297:Male; D010314:Partial Thromboplastin Time; D010446:Peptide Fragments / Q000032:analysis; D010976:Platelet Count; D011486:Protein C / Q000032:analysis; D017293:Protein S / Q000032:analysis; D011516:Prothrombin / Q000032:analysis; D011517:Prothrombin Time; D014859:Warfarin / Q000627:therapeutic use; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D000925:Anticoagulants; D005338:Fibrin Fibrinogen Degradation Products; D006454:Hemoglobins; D010446:Peptide Fragments; D011486:Protein C; D017293:Protein S; C036309:fibrin fragment D; C045879:prothrombin fragment 1.2; D014841:von Willebrand Factor; D005344:Fibrinopeptide A; D014859:Warfarin; D000990:Antithrombin III; D011516:Prothrombin; D005169:Factor VIII; D005340:Fibrinogen