Associations between atrial fibrillation and early outcomes of patients with heart failure and reduced or preserved ejection fraction

Background The relative impact of atrial fibrillation on early outcomes of patients with heart failure with reduced or preserved ejection fraction (EF) is unknown. Methods We conducted a retrospective cohort study of clinical registry data linked to Medicare claims for patients with heart failure with reduced or preserved EF stratified by presence of atrial fibrillation at admission. Outcomes of interest were all-cause mortality and readmission at 30 days. We used Kaplan-Meier methods to estimate mortality and calculated cumulative incidence estimates of readmission. We used Cox proportional hazards models to examine associations between atrial fibrillation and 30-day outcomes. Results Among 66,357 patients admitted to 283 hospitals between January 2001 and March 2006, 46% had atrial fibrillation (44% of patients with reduced EF and 48% of patients with preserved EF). After adjustment for other patient characteristics, atrial fibrillation was associated with a modestly higher risk of 30-day mortality (HR, 1.08; 95% CI, 1.03-1.14) and readmission (HR, 1.06; 95% CI, 1.02-1.11). In subgroup analyses, atrial fibrillation was associated with a higher risk of 30-day mortality (HR, 1.16; 95% CI, 1.08-1.25) among patients with preserved EF but not among patients with reduced EF. The association of atrial fibrillation with readmission did not differ by heart failure type (P = .37 for the interaction). Conclusions Atrial fibrillation was associated with higher 30-day mortality among patients with heart failure with preserved EF but not reduced EF. The association of atrial fibrillation with 30-day readmission was modest and did not differ by heart failure type.