title: Effect of hyperthyroidism on the hypercoagulable state and thromboembolic events in patients with atrial fibrillation.
abstract: OBJECTIVE
  To clarify whether hyperthyroidism (HT) itself confers an additional effect on the hypercoagulable state and the risk of ischemic stroke among patients with hyperthyroid atrial fibrillation (AF).
  
  
  METHODS
  We prospectively evaluated plasma D-dimer levels and thromboembolic events among three groups of patients (hyperthyroid AF, n = 62; nonthyroid AF, n = 107, and HT without AF, n = 100). Plasma D-dimer levels were used to evaluate the hypercoagulable state.
  
  
  RESULTS
  The D-dimer level was significantly higher in patients with hyperthyroid AF than in nonthyroid AF (0.66 ± 0.06 vs. 0.34 ± 0.02 mg/l, p < 0.001) and HT without AF (0.66 ± 0.06 vs. 0.27 ± 0.02 mg/l, p < 0.001). During a 3-year follow-up, patients with hyperthyroid AF had a significantly higher incidence of ischemic stroke compared with patients with nonthyroid AF (hazard ratio, HR: 3.2, 95% confidence interval, CI: 1.01-5.59, p = 0.04). Cox regression analysis revealed that age (HR: 2.5, 95% CI: 1.01-1.21, p = 0.05), CHADS2-VAS score (HR: 5.5, 95% CI: 1.51-7.43, p = 0.01) and anticoagulation (HR: 0.45, 95% CI: 0.07-0.54, p = 0.01) were independent predictors of risk for the occurrence of ischemic stroke.
  
  
  CONCLUSIONS
  The present study suggests that HT may enhance the hypercoagulable state and the risk of ischemic stroke in patients with AF.
authors.affiliation: Department of Cardiology, Zhongshan Hospital, Shanghai Institute of Cardiovascular Diseases, Shanghai, China.
authors.forename: Qingxing
authors.initials: Q
authors.lastname: Chen
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Kuan
authors.initials: K
authors.lastname: Cheng
authors.forename: Yuping
authors.initials: Y
authors.lastname: Liu
authors.forename: Wenqing
authors.initials: W
authors.lastname: Zhu
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000097:blood / Q000150:complications*; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism; D005342:Fibrinolysis / Q000502:physiology; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood / Q000150:complications*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D020521:Stroke / Q000097:blood / Q000209:etiology / Q000517:prevention & control; D013923:Thromboembolism / Q000097:blood / Q000209:etiology* / Q000517:prevention & control; D019851:Thrombophilia / Q000097:blood / Q000209:etiology* / Q000517:prevention & control
chemical_list: D000925:Anticoagulants; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D