Incidence of atrial fibrillation in conjunction with breast cancer

Patients with breast cancer may have an increased incidence of atrial fibrillation (AF) because of the systemic inflammation induced by the cancer and side effects of treatments.

The purpose of this study was to estimate the long-term incidence of AF in patients with breast cancer compared with the background population.

We identified patients diagnosed with breast cancer from 1998 to 2015 by using nationwide registries. Female patients with breast cancer were matched (1:3) by age and sex with the background population. The long-term incidence of AF was estimated by cumulative incidence curves and multivariable Cox regression models.

We matched 74,155 patients with breast cancer with 222,465 patients from the background population. Breast cancer was associated with incident AF and the association differed between age groups (interaction analysis, P < .0001) and follow-up time periods. In patients younger than 60 years breast cancer was associated with increased incidence of AF during the first 6 months (hazard ratio [HR] 2.10; 95% confidence interval [CI] 1.25-3.44) and from 6 months to 3 years (HR 1.80; 95% CI 1.38-2.35). In patients older than 60 years, breast cancer was not associated with increased incidence of AF during the first 6 months (HR 1.13; 95% CI 0.95-1.34) and was associated with increased incidence of AF from 6 months to 3 years (HR 1.14; 95% CI 1.05-1.25).

The long-term incidence of AF was increased in patients with breast cancer and short-term incidence was increased in patients younger than 60 years and similar in patients older than 60 years compared with the background population.