Introduction: Atrial fibrillation and flutter (AFF) are the most common arrhythmias presenting to the emergency department. A coordinated ED AFF electronic order-set and management pathway was developed in collaboration with cardiologists at our institution. The primary objective of this study was to compare the ED length of stay pre and post pathway implementation. Secondary objectives included comparison of the following outcomes pre and post-pathway (PRE & POST): AFF Clinic referral rates, ED return rates, and mortality. Methods: This was a retrospective case series of patients presenting to our quarternary care ED with AFF pre and post AFF pathway implementation. Cases were identified using an administrative database covering 120 000 annual ED visits. Trained research assistants and the primary investigator extracted data from the electronic medical record. 20% of all charts were double collected to ensure accuracy (k=0.85). Descriptive variables were described using counts, means, medians and confidence intervals. Chi-square statistics of dependent samples were calculated for the primary outcome. Results: We examined 307 cases of AFF presenting to our ED (n=130 PRE; n=177 POST). Demographic variables were similar PRE and POST: mean age (66.0 [95%CI 63.8-68.3] PRE; 65.0 [63.0-67.0] POST), % male (59.2% PRE; 59.3% POST), presenting rhythm (66.2% A.fib [58.0-74.3] A. flutter 29.2% [21.4-37.0] PRE; 61.0% A.fib [53.8-68.1] A. flutter 17.5% [11.9-23.1] POST), and CHADS2VASC score (2.1 [1.8-2.4] PRE; 1.9 [1.7-2.1] POST). The mean ED LOS decreased by 72.5 minutes (95% CI -22.9 to -122.1; P < 0.001). AFF clinic referral rates increased from 16.9% PRE to 25.4% POST (not significant). ED return rates within 30 days for AFF, CHF, major bleeding and CVA were unchanged. 30 day mortality rates were not statistically different (1.5% PRE vs. 2.8% POST). Conclusion: A coordinated ED AFF pathway was associated with a significant reduction in ED LOS without significant changes in ED return rates or mortality.