Abstract 6937: Atrial Fibrillation in Breast Cancer Patients: Incidence, Prevalence, Risk Factors, and Mortality: Longitudinal Seer-Medicare Analysis

Abstract

Background: The national incidence, risk factor, and associated mortality of atrial fibrillation (AF) in early or advanced breast cancer patients are unknown. Methods: Using the Surveillance, Epidemiology, and End Results-Medicare linked database, we identified females, ≥ 66-year-old, with a new primary diagnosis of breast cancer from 2007 through 2014. These patients were individually matched 1:1 to Medicare enrollees without cancer, and each pair was followed for one year to identify a primary outcome of AF. Cumulative incidence rates were calculated using competing risk survival statistics. Following this, risk factor analysis was conducted using the adjusted Cox proportional hazards model. Finally, Kaplan-Meier methods and adjusted Cox proportional hazards modeling were performed to estimate mortality in breast cancer patients with incident and AF prior to breast cancer diagnosis. Results: This study included 85,423 breast cancer patients. Among these 9,425 (11.0%) had AF diagnosis prior to the breast cancer diagnosis. New AF was diagnosed in 2,993 (3.9%) patients in a 1-year period after the breast cancer diagnosis [incidence rate = 3.3% (95% CI = 3.0% - 3.5%) at 1-year; highest rate in the first two months (0.6%/month)]. The population standardized AF incidence was higher in Black compared to White females (58.8 vs. 49.9 per 1000 person-years in 2014, respectively). Apart from traditional demographic and cardiovascular risk factors, breast cancer stage was strongly associated with development of AF [AJCC Stage II vs. I: adjusted HR (aHR)= 1.51 (95% CI= 1.37 - 1.65); AJCC Stage III vs. I: aHR= 2.63 (95% CI= 2.35 - 2.94); AJCC Stage IV vs. I: aHR= 4.21 (95% CI= 4.04 - 5.48)]. New onset AF after breast cancer diagnosis [aHR = 3.51 (95% CI = 1.69 - 7.32)] and AF prior to breast cancer diagnosis [aHR = 1.70 (95% CI = 1.26 - 2.29)] was associated with increased 1-year- cardiovascular mortality. Conclusion: AF incidence is significantly higher in women after a breast cancer diagnosis. Apart from traditional risk factors, higher breast cancer stages at diagnosis are significantly associated with a higher risk of AF. New or prior AF in the setting of new breast cancer increases 1-year cardiovascular mortality.