title: Asymptomatic embolisation in non-valvular atrial fibrillation and its relationship to anticoagulation therapy.
abstract: OBJECTIVE
  A prospective study to determine the prevalence of embolic signals (ES) detected with transcranial Doppler ultrasound (TCD) in subjects with non-valvular atrial fibrillation (NVAF) who were and were not taking anticoagulants.
  
  
  METHODS
  Sixty-eight subjects with NVAF taking warfarin and sixty-three NVAF subjects not taking warfarin were recruited from the cardiology department. No patients had suffered a previous stroke or clinical systemic embolisation. Thirty subjects in sinus rhythm were recruited as controls. TCD recordings were performed bilaterally from the middle cerebral arteries for 1 h. In 126 subjects (96%) the recording was repeated 1 week later. All Doppler recordings were reviewed blindly by an observer for ES.
  
  
  RESULTS
  After one recording ES were detected in one warfarin NVAF subject (1.5%), four non-warfarin NVAF subjects (6.3%) and no sinus rhythm controls. Following both recordings ES were detected in one warfarin NVAF subject (1.5%) and seven non-warfarin NVAF subjects (11.9%) P = 0.017.
  
  
  CONCLUSIONS
  Asymptomatic ES can be detected in a minority of subjects with NVAF. These signals were significantly less common in NVAF subjects taking warfarin, and this is consistent with asymptomatic ES having clinical significance in this disease. TCD detection of ES may have application in patients with NVAF for risk stratification, and assessment of the efficacy of new anti-platelet and anti-thrombotic regimens in the condition. Further large prospective studies are required to determine whether ES predict stroke risk in this patient group.
authors.affiliation: Department of Surgery, Royal Free Hampstead NHS Trust, London, UK.
authors.forename: Kerry
authors.initials: K
authors.lastname: Tinkler
authors.forename: Marisa
authors.initials: M
authors.lastname: Cullinane
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Kaposzta
authors.forename: Hugh S
authors.initials: HS
authors.lastname: Markus
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000150:complications* / Q000188:drug therapy*; D016022:Case-Control Studies; D004617:Embolism / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D017585:Ultrasonography, Doppler, Transcranial; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin