Atrial fibrillation (AF) is an increasingly recognized co-diagnosis in patients with cancer.

This study aimed to provide a robust and contemporary estimate on the co-prevalence and relative risk of AF in patients with cancer.

We conducted a nationwide analysis, utilizing diagnosis codes from the Austrian Association of Social Security Providers (AASSP) dataset. Estimates of the co-prevalence of cancer and AF and the relative risk of AF in cancer patients compared to individuals without cancer were obtained as point prevalences with binomial exact confidence intervals and summarized across age groups and cancer types with random-effects models.

8,306,244 persons were included in the present analysis, of whom 158,675 (prevalence estimate: 1.91%, 95% confidence interval [CI]: 1.90-1.92) had a cancer diagnosis code and 112,827 (1.36%, 95%CI: 1.35-1.36) an AF diagnosis code, respectively. The prevalence estimate for AF in patients with cancer was 9.77% (95%CI: 9.63-9.92) and 1.19% (95%CI: 1.19-1.20) in the non-cancer population. Conversely, 13.74% (95%CI: 13.54-13.94) of patients with AF had a concurrent cancer diagnosis. The corresponding age-stratified random-effects relative risk ratio for AF in patients with cancer compared to no cancer diagnosis was 10.45 (95%CI: 7.47-14.62). The strongest associations between cancer and AF were observed in younger persons and patients with hematologic malignancies.

Cancer and AF have a substantial co-prevalence in the population. This finding corroborates the concept that cancer and AF have common risk factors and pathophysiology.