title: Thromboembolic events occur despite sinus rhythm maintenance in patients treated for atrial fibrillation: The Canadian Trial of Atrial Fibrillation experience.
abstract: BACKGROUND
  Anticoagulation reduces the risk of stroke in patients with atrial fibrillation. It is not clear whether patients who revert and are maintained in sinus rhythm should continue to receive warfarin. The recommendation is to anticoagulate these patients for a minimum of four weeks after cardioversion. Whether warfarin should be maintained for a longer period of time is unknown.
  
  
  RESULTS
  To address this question, data from the Canadian Trial of Atrial Fibrillation were reviewed. Among the 403 patients, 81.9% had at least one risk factor for stroke, of whom only 60% were on warfarin. Nine thromboembolic events occurred in nine patients (2.2%): all had at least one risk factor for stroke. Six events occurred in patients who were either not anticoagulated (n=4) or for whom the international normalization ratio was subtherapeutic (n=2). Eight of the nine patients were in sinus rhythm at the last follow-up visit before and at the time of evaluation of the thromboembolic event.
  
  
  CONCLUSIONS
  Anticoagulants are underused in atrial fibrillation patients at risk of stroke. Thromboembolic events are most often associated with suboptimal levels of anticoagulation and they occur despite the appearance of sinus rhythm maintenance.
authors.affiliation: Research Centre, Montreal Heart Institute, Quebec. ablation2000@hotmail.com
authors.forename: Bernard
authors.initials: B
authors.lastname: Thibault
authors.forename: Mario
authors.initials: M
authors.lastname: Talajic
authors.forename: Marc
authors.initials: M
authors.lastname: Dubuc
authors.forename: Peter
authors.initials: P
authors.lastname: Guerra
authors.forename: Pierre
authors.initials: P
authors.lastname: Gagné
authors.forename: Denis
authors.initials: D
authors.lastname: Roy
authors.forename: Stuart
authors.initials: S
authors.lastname: Connolly
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000453:epidemiology / Q000628:therapy*; D002170:Canada / Q000453:epidemiology; D004554:Electric Countershock; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000187:drug effects / Q000473:pathology*; D006470:Hemorrhage / Q000139:chemically induced / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D019934:International Normalized Ratio; D002546:Ischemic Attack, Transient / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012720:Severity of Illness Index; D013223:Statistics as Topic; D020521:Stroke / Q000453:epidemiology / Q000209:etiology; D013923:Thromboembolism / Q000453:epidemiology / Q000209:etiology*; D017211:Treatment Failure; D014859:Warfarin / Q000627:therapeutic use
chemical_list: D000925:Anticoagulants; D014859:Warfarin