Increased risk of atrial fibrillation in patients with coeliac disease: a nationwide cohort study

Aims Inflammatory markers are established risk factors for atrial fibrillation (AF), but the role of autoimmune diseases is unknown. The aim of the study was to examine the association between coeliac disease (CD) and AF in a large cohort of patients with biopsy-verified CD. Methods and results We identified 28 637 patients with CD through biopsy reports (defined as Marsh 3: villous atrophy) from all pathology departments (n = 28) in Sweden. Biopsies had been performed between 1969 and 2008. Age-and sexmatched reference individuals (n = 141 731) were identified from the Swedish Total Population Register. Data on AF were obtained from the Swedish Hospital Discharge Register, the Hospital Outpatient Register, and the Cause of Death Register. Hazard ratios (HRs) for AF were estimated using Cox regression. In the CD cohort, 941 individuals developed AF (vs. 2918 reference individuals) during a median follow-up of 9 years. The corresponding adjusted HR for AF was 1.34 (95% CI 1.24-1.44). The absolute risk of AF in CD was 321 of 100 000 person-years, with an excess risk of 81 of 100 000. A prior AF diagnosis was also associated with an increased risk of subsequent CD (odds ratio 1.45, 95% CI 1.31-1.62). Conclusions Atrial fibrillation is more common both before and after CD diagnosis in patients with CD though the excess risk is small. Potential explanations for the increased risk of AF in CD include chronic inflammation and shared risk factors, but ascertainment bias may also have contributed. Clinical implications Coeliac disease affects 1-2% of the Western population. Our results indicate that patients with coeliac disease, verified by intestinal biopsy, are at increased risk of atrial fibrillation. This observation is consistent with previous findings that elevation of inflammatory markers predicts atrial fibrillation. Additional studies are needed to clarify the mechanistic link between atrial fibrillation and autoimmune diseases such as coeliac disease.