title: Presence of atrial fibrillation is associated with liver stiffness in an elderly Finnish population.
abstract: BACKGROUND
  Chronic liver injury from different etiologies drives liver fibrosis. However, little is known about the associated factors, systemic factors in particular. Recently, non-alcoholic fatty liver disease (NAFLD) and atrial fibrillation have been shown to be associated with each other. Thereby, we aimed to study the association between atrial fibrillation and liver stiffness.
  
  
  METHODS
  Extensive clinical measurements including echocardiography of the heart, transient elastography (TE) of the liver and the presence of atrial fibrillation were determined in elderly Finnish study subjects (n = 76, mean age 73 years) from OPERA (Oulu Project Elucidating the Risk of Atherosclerosis) study cohort. Half of the study subjects had non-alcoholic fatty liver disease, whereas others did not have any known hepatic morbidity. The present study was cross-sectional by nature.
  
  
  RESULTS
  The subjects with atrial fibrillation had higher TE values (with atrial fibrillation TE = 9.3kPa, without atrial fibrillation TE = 6.3kPa, p = 0.018). When the cohort was divided to four subgroups (those without NAFLD or atrial fibrillation, with NAFLD but without atrial fibrillation, with both conditions, and with atrial fibrillation but without NAFLD), the TE value was the highest in the subjects with both conditions (5.3kPa, 7.4kPa, 10.8kPa and 7.8kPa, respectively, p = 0.019). Moreover, the higher the TE value, the more prevalent atrial fibrillation was (the atrial fibrillation prevalence by tertiles of TE 27% / 36% / 77%, p = 0.001). Likewise, the greater the TE value, the greater the left atrial diameter, a collateral of atrial fibrillation (left atrial diameters by tertiles of TE 39mm / 45mm / 48mm, p<0.001) was. All these p-values for continuous variables remained statistically significant even after adjustment for common clinically relevant risk factors.
  
  
  CONCLUSIONS
  There is an association between atrial fibrillation and liver stiffness. This novel association may have multiple explanations and mechanistic links, which are discussed here and need further studies, prospective studies in particular.
authors.affiliation: Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital, and University of Oulu, Oulu, Finland.|Abdominal Center, Department of Internal Medicine, Oulu University Hospital, Oulu, Finland.
authors.forename: Aki Juhani
authors.initials: AJ
authors.lastname: Käräjämäki
authors.affiliation: Abdominal Center, Department of Internal Medicine, Oulu University Hospital, Oulu, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Kettunen
authors.affiliation: Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital, and University of Oulu, Oulu, Finland.
authors.forename: Samuli
authors.initials: S
authors.lastname: Lepojärvi
authors.affiliation: Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital, and University of Oulu, Oulu, Finland.|Abdominal Center, Department of Internal Medicine, Oulu University Hospital, Oulu, Finland.
authors.forename: Olli-Pekka
authors.initials: OP
authors.lastname: Koivurova
authors.affiliation: Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital, and University of Oulu, Oulu, Finland.
authors.forename: Y Antero
authors.initials: YA
authors.lastname: Kesäniemi
authors.affiliation: Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital, and University of Oulu, Oulu, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Huikuri
authors.affiliation: Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital, and University of Oulu, Oulu, Finland.
authors.forename: Olavi
authors.initials: O
authors.lastname: Ukkola
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000150:complications*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D054459:Elasticity Imaging Techniques; D005260:Female; D005387:Finland; D006801:Humans; D008099:Liver / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease / Q000150:complications / Q000503:physiopathology*