title: Venous thromboembolism increases the risk of atrial fibrillation: the Tromso study.
abstract: BACKGROUND
  Pulmonary embolism (PE) may trigger atrial fibrillation through increased right atrial pressure and subsequent atrial strain, but the degree of evidence is low. In this study, we wanted to investigate the impact of incident venous thromboembolism (VTE) on future risk of atrial fibrillation in a prospective population-based study.
  
  
  RESULTS
  The study included 29 974 subjects recruited from the Tromsø study (1994-1995, 2001-2002, 2007-2008). Incident VTE and atrial fibrillation events were registered from date of enrolment to end of follow-up, December 31, 2010. Cox proportional hazard regression models using age as time-scale and VTE as a time-dependent variable were used to estimate crude and multivariable hazard ratios (HRs) for atrial fibrillation with 95% confidence intervals (CIs). During 16 years of follow up, 540 (1.8%) subjects had an incident VTE event, and 1662 (5.54%) were diagnosed with atrial fibrillation. Among those with VTE, 50 (9.3%) developed subsequent atrial fibrillation. Patients with VTE had 63% higher risk of atrial fibrillation compared to subjects without VTE (multivariable-adjusted HR: 1.63, 95% CI: 1.22 to 2.17). The risk of atrial fibrillation was particularly high during the first 6 months after the VTE event (HR 4.00, 95% CI: 2.21 to 7.25) and among those with PE (HR 1.78, 95% CI: 1.13 to 2.80).
  
  
  CONCLUSIONS
  We found that incident VTE was associated with future risk of atrial fibrillation. Our findings support the hypothesis that PE may lead to cardiac dysfunctions that, in turn, could trigger atrial fibrillation.
authors.affiliation: Hematological Research Group, Department of Clinical Medicine, University of Tromsø, Tromsø, Norway.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Hald
authors.forename: Kristin F
authors.initials: KF
authors.lastname: Enga
authors.forename: Maja-Lisa
authors.initials: ML
authors.lastname: Løchen
authors.forename: Ellisiv B
authors.initials: EB
authors.lastname: Mathiesen
authors.forename: Inger
authors.initials: I
authors.lastname: Njølstad
authors.forename: Tom
authors.initials: T
authors.lastname: Wilsgaard
authors.forename: Sigrid K
authors.initials: SK
authors.lastname: Braekkan
authors.forename: John-Bjarne
authors.initials: JB
authors.lastname: Hansen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000453:epidemiology*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009664:Norway / Q000453:epidemiology; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D054556:Venous Thromboembolism / Q000175:diagnosis / Q000453:epidemiology*
keywords: epidemiology; fibrillation; pulmonary heart disease; thrombosis