Currently, 11% of patients seen in the emergency department for atrial fibrillation die within 1 year of the visit. Our objective was to examine the association of rapid (within 3 days), early (7 days), and basic (30 days) outpatient physician follow-up with short- and long-term outcomes in patients with atrial fibrillation discharged from an emergency department.This retrospective cohort study included all adult patients discharged from one of the 163 emergency departments in Ontario, Canada with a primary diagnosis of atrial fibrillation, 2007 to 2014. We used a landmark analysis with propensity score matching, and logistic regression, to assess all-cause mortality and cardiovascular hospitalizations at 1 year and 90 days, 30-day return emergency visits, and 1-year oral anticoagulation prescription fills.In the 10 657 patients with rapid follow-up care who were propensity score matched to a patient with follow-up between days 4 and 7, the hazard of a return emergency visit was reduced by 11% (HR, 0.89 [95% CI, 0.80-0.98]). It was not associated with mortality or hospitalization. In the 17 234 patients with early follow-up who were matched to a patient with care between days 8 and 30, the rate of 1-year mortality was 11% lower (HR, 0.89 [95% CI, 0.81-0.97]) and 1-year hospitalization was 6% lower (HR, 0.94 [95% CI, 0.89-1.00]). Relative to no 30-day care, basic follow-up care was associated with an increased hazard of 90-day hospitalization (HR, 1.32 [95% CI, 1.12-1.56]) but was no longer associated with mortality. In patients with early follow-up, the odds of filling an oral anticoagulation prescription a year later were 64% higher than those without it (OR, 1.64 [95% CI, 1.54-1.78]).Compared with follow-up care between days 8 and 30, follow-up within a week after discharge from an emergency department with atrial fibrillation was associated with a reduction in the rate of death and hospitalization within 1 year, an association that was not present with 30-day follow-up.