title: Benefit of Anticoagulation Therapy in Hyperthyroidism-Related Atrial Fibrillation.
abstract: BACKGROUND
  Existing data on the risk of ischemic stroke in hyperthyroidism-related atrial fibrillation (AF) and the impact of long-term anticoagulation in these patients, particularly those with self-limiting AF, remain inconclusive.
  
  
  OBJECTIVE
  Risk of stroke in hyperthyroidism-related AF is the same as nonhyperthyroid counterparts.
  
  
  METHODS
  This was a single-center observational study of 9727 Chinese patients with nonvalvular AF from July 1997 to December 2011. Patients with AF diagnosed concomitantly with hyperthyroidism were identified. Primary and secondary endpoints were defined as hospitalization with ischemic stroke and intracranial hemorrhage in the first 2 years. Patient characteristics, duration of AF, and choice of antithrombotic therapy were recorded. Self-limiting AF was defined as <7 days' duration.
  
  
  RESULTS
  Out of 9727 patients, 642 (6.6%) had concomitant hyperthyroidism and AF at diagnosis. For stroke prevention, 136 and 243 patients (21.1% and 37.9%) were prescribed warfarin and aspirin, respectively, whereas the remaining patients (41.0%) received no therapy. Ischemic stroke occurred in 50 patients (7.8%), and no patient developed hemorrhagic stroke. Patients with CHA2 DS2 -VASc of 0 did not develop stroke. Warfarin effectively reduced the incidence of stroke compared with aspirin or no therapy in patients with CHA2 DS2 -VASc ≥1 and non-self-limiting AF, but not in those with self-limiting AF or CHA2 DS2 -VASc of 0. Presence of hyperthyroidism did not confer additional risk of ischemic stroke compared with nonhyperthyroid AF.
  
  
  CONCLUSIONS
  Patients with hyperthyroidism-related AF are at high risk of stroke (3.9% per year). Warfarin confers stroke prevention in patients with CHA2 DS2 -VASc ≥1 and non-self-limiting AF. Overall stroke risk was lower in hyperthyroid non-self-limiting AF patients compared with nonhyperthyroid counterparts.
authors.affiliation: Division of Cardiology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Pak-Hei
authors.initials: PH
authors.lastname: Chan
authors.affiliation: Division of Cardiology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Jojo
authors.initials: J
authors.lastname: Hai
authors.affiliation: Research Center of Heart, Brain, Hormone and Healthy Aging, LKS Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Chun-Yip
authors.initials: CY
authors.lastname: Yeung
authors.affiliation: University of Birmingham, Centre for Cardiovascular Sciences (Lip), City Hospital, Birmingham, United Kingdom.
authors.forename: Gregory Y H
authors.initials: GY
authors.lastname: Lip
authors.affiliation: Research Center of Heart, Brain, Hormone and Healthy Aging, LKS Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China.|Division of Endocrinology and Metabolism, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Karen Siu-Ling
authors.initials: KS
authors.lastname: Lam
authors.affiliation: Division of Cardiology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR, China.|Research Center of Heart, Brain, Hormone and Healthy Aging, LKS Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
authors.affiliation: Division of Cardiology, Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR, China.|Research Center of Heart, Brain, Hormone and Healthy Aging, LKS Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China.
authors.forename: Chung-Wah
authors.initials: CW
authors.lastname: Siu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D044466:Asian People; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy*; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications* / Q000188:drug therapy; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000209:etiology; D016019:Survival Analysis; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin