The prevalence of atrial fibrillation in a geographically well-defined population in Northern Sweden: implications for anticoagulation prophylaxis.

Objectives: The aims of this study were to evaluate the community-based prevalence of atrial fibrillation (AF) in a western society using a geographically well-defined population in the northern part of Sweden as a reference and to estimate the proportion of patients eligible for oral anticoagulation (OAC) prophylactic therapy according to the stroke risk indices CHADS(2) and CHA(2) DS(2) -VASc. Bleeding risk was assessed using the HAS-BLED score. Design: The study population was recruited from AURICULA, a Swedish national quality register for patients receiving anticoagulation treatment. All patients with the diagnosis AF in the catchment area are registered in AURICULA. Results: Of the 65,532 inhabitants in the catchment area, 1616 were diagnosed with AF (1200 cases were characterized as chronic AF). Thus, the overall prevalence of AF was 2.5%. The prevalence increased with age from 6.3% in patients over 55 years of age to 13.8% in those over 80 years. The prevalence was higher in men than in women in all age groups. Overall, 56.3% and 85.1% of the population were at high risk of stroke (≥2 points) according to CHADS(2) and CHA(2) DS(2) -VASc, respectively. In addition, 26.9% had an increased bleeding risk according to HAS-BLED. Conclusion: Within this large Caucasian population, we identified the highest community-based prevalence of AF to date. The prevalence was strongly associated with increasing age and male gender. Using CHA(2) DS(2) -VASc instead of CHADS(2) widened the indication for OAC prophylactic therapy of AF in this population.