title: Risk factors for incident atrial fibrillation with and without left atrial enlargement in women.
abstract: BACKGROUND
  Left atrial (LA) enlargement facilitates induction and/or maintenance of atrial fibrillation (AF). However, little is known about risk factors for AF with normal LA size.
  
  
  METHODS
  We prospectively followed 34713 initially healthy women for incident AF. Information on echocardiographic LA size at first AF diagnosis was abstracted from medical charts during AF confirmation. LA enlargement was defined as LA diameter >40 mm. Using a competing risk approach, we constructed Cox proportional-hazards models to calculate hazard ratios (HR) and 95% confidence intervals (CI) of risk factors for incident AF with and without LA enlargement, respectively.
  
  
  RESULTS
  Among 796 women with incident AF and available LA size, 328 (41%) had LA enlargement. In multivariable competing risk models, the relationship between age and incident AF was stronger in those with (HR 1.12, 95% CI 1.10-1.14) versus without (HR 1.08, 95% CI 1.06-1.09) LA enlargement (p for difference <0.0001). Body weight was associated with AF only in the presence of LA enlargement (HR per 10 kg 1.34, 95% CI 1.26-1.43; versus 1.07, 95% CI 0.998-1.14, p for difference<0.0001). Hypertension and height were significantly associated with AF both in the presence (HR 1.99, 95% CI 1.49-2.65; and HR per 10 cm 1.36, 95% CI 1.13-1.63) and absence (1.55, 1.25-1.92 and 1.29, 1.10-1.50) of LA enlargement (p for difference 0.17 and 0.66, respectively).
  
  
  CONCLUSIONS
  These data suggest that LA enlargement explains much of the increased AF risk associated with obesity and age. In contrast, height and hypertension appear to also influence AF risk through other mechanisms besides LA enlargement.
authors: Center for Arrhythmia Prevention, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Department of Medicine, University Hospital, Basel, Switzerland, United States. Electronic address: conend@uhbs.ch.
authors: David
authors: D
authors: Conen
authors: Robert J
authors: RJ
authors: Glynn
authors: Roopinder K
authors: RK
authors: Sandhu
authors: Usha B
authors: UB
authors: Tedrow
authors: Christine M
authors: CM
authors: Albert
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D004311:Double-Blind Method; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006325:Heart Atria / Q000000981:diagnostic imaging*; D006801:Humans; D006973:Hypertension / Q000150:complications* / Q000453:epidemiology; D015994:Incidence; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
keywords: Atrial fibrillation; Hypertension; Left atrium; Obesity; Women