title: Paroxysmal atrial fibrillation and the hazards of under-treatment.
abstract: OBJECTIVE
  Oral anticoagulants are highly efficacious for the prevention of stroke in atrial fibrillation, and are the preferred treatment by current guidelines. The purpose of our study was to assess the utilization of antithrombotic drugs in atrial fibrillation patients at the time of ischemic stroke and the factors associated with their use.
  
  
  METHODS
  We enrolled 759 consecutive patients admitted with ischemic stroke at Boston Medical Center, Geisinger Health System, and the University of Alabama. To be eligible, patients had to have electrocardiographically-confirmed atrial fibrillation at the time of admission or within 6 months of the index stroke. All stroke events and electrocardiograms were validated by study physicians. Patients with newly diagnosed atrial fibrillation were not eligible.
  
  
  RESULTS
  The mean age was 78 years, 43% were male, 19% black, and the mean CHADS2 score is 3.0. Atrial fibrillation was paroxysmal in 31%. At presentation, 181 (24%) patients were taking warfarin only, 96 (13%) both warfarin and aspirin, 294 (39%) aspirin alone, and 189 (25%) no antithrombotic therapy. The mean international normalized ratio was 1.6. Among patients with paroxysmal atrial fibrillation, one in five was taking warfarin. Although increasing stroke risk was associated with a greater likelihood of warfarin use, only 39% of highest risk CHADS2 3-6 were taking warfarin at the time of stroke.
  
  
  CONCLUSIONS
  Among high-risk individuals with atrial fibrillation, only 37% were taking warfarin at the time of stroke. Paroxysmal atrial fibrillation was associated with the highest risk of not receiving warfarin.
authors.affiliation: Department of Medicine, Boston Medical Center, Boston University, 801 Massachusetts Avenue, Crosstown 2, Boston, MA 02118 USA. Electronic address: konstantinos.aronis@bmc.org.
authors.forename: Konstantinos N
authors.initials: KN
authors.lastname: Aronis
authors.affiliation: Department of Pharmacy, Notre Dame of Maryland University, Baltimore, MD, USA.
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Thigpen
authors.affiliation: Department of Biostatistics, Boston University School of Public Health, Boston, MA USA.
authors.forename: Yorghos
authors.initials: Y
authors.lastname: Tripodis
authors.affiliation: Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Chrisly
authors.initials: C
authors.lastname: Dillon
authors.affiliation: Department of Cardiology, Geisinger Health System, Danville, PA, USA.
authors.forename: Kristen
authors.initials: K
authors.lastname: Forster
authors.affiliation: Department of Medicine, Boston Medical Center, Boston University, 801 Massachusetts Avenue, Crosstown 2, Boston, MA 02118 USA.
authors.forename: Lori
authors.initials: L
authors.lastname: Henault
authors.affiliation: Department of Biostatistics, Boston University School of Public Health, Boston, MA USA.
authors.forename: Emily Kate
authors.initials: EK
authors.lastname: Quinn
authors.affiliation: Department of Cardiology, Geisinger Health System, Danville, PA, USA.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Berger
authors.affiliation: Department of Biostatistics, Boston University School of Public Health, Boston, MA USA.
authors.forename: Nita A
authors.initials: NA
authors.lastname: Limdi
authors.affiliation: Department of Medicine, Boston Medical Center, Boston University, 801 Massachusetts Avenue, Crosstown 2, Boston, MA 02118 USA.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hylek
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D002545:Brain Ischemia / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage*; D005500:Follow-Up Studies; D006300:Health Services Misuse; D006801:Humans; D015994:Incidence; D008297:Male; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013614:Tachycardia, Paroxysmal / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D013923:Thromboembolism / Q000150:complications / Q000453:epidemiology / Q000517:prevention & control*; D014481:United States / Q000453:epidemiology
chemical_list: D005343:Fibrinolytic Agents
keywords: Atrial fibrillation; Embolic stroke; Oral anticoagulation; Warfarin utilization