Background: The aim of the study was to estimate the sex-specific prevalence and incidence of atrial fibrillation or flutter (AF) in the German population-based Heinz Nixdorf Recall study.

Methods: We analysed data from 4814 participants at baseline 2000-2003 (T0, 50.2% women, 45-75 years), first and second follow-up examination (T1: n=4157, 2005-2008; T2: n=3087, 2010-2015) and yearly postal questionnaires for the AF occurrence until 29 November 2023. We determined the AF prevalence at T0, if participants were aware of having AF at T0, if participants with ECG-proven AF at T0 were anticoagulated, the cumulative incidence and the incidence rate per 1000 person-years over two decades of follow-up.

Results: Overall, 152 (3.2%) participants were identified with AF at or before T0. Of those, only n=89 (58.6%) participants were able to name an existing AF diagnosis. n=80 (1.7%) participants had ECG-confirmed AF and 13 (0.3%) participants were not aware of having AF at T0. Of 4662 participants without AF at T0, 640 (13.7%) developed AF during a median follow-up time of 16.7 (Q1; Q3: 10.5-18.9) years. The overall incidence rate was 9.4 (95% CI: 8.7 to 10.1) per 1000 person-years.

Conclusions: The results of our study show that AF is an epidemic disease in the middle-aged and elderly population. The proportion of patients who do not know that they have AF should be reduced in the future. Patients also need to be better informed about their disease and anticoagulation. This is important in order to prevent avoidable adverse events.