Introduction: Pulmonary Embolism (PE) management in Emergency Department (ED) confers a substantial cost burden representing opportunities for improvements in decision-making. The Pulmonary Embolism Severity Index (PESI) is a validated tool to prognosticate patients with PE supporting admit versus (vs.) discharge decisions from the ED. Despite existing evidence, PESI is under-used in patients with PE. We sought to evaluate PESI scores and patient disposition from 4 EDs within Calgary to determine discordance between them and the effect of the discordance on readmission and mortality. Methods: Retrospective review of adult patients 18 years, diagnosed with PE between January-June 2016 at 4 EDs in Calgary Health Region. Patients were divided into high-risk PESI (score>85) and low-risk PESI (score 0-85). Chi-Square (2) test was used for comparison between the groups. Primary outcome measure was rate of discordance between PESI risk and disposition decision and identify factors driving the discordance. Secondary outcome measures included comparing 30-day readmission rate, 30-day and 90-day mortality between the discordant PESI groups. Results: 365 patients were diagnosed with PE in the study period with 60% being admitted and 40% discharged. The median PESI score in admitted patients was 85 (26-172) vs. 68 (20-163) in discharged patients. 51% of admitted patients had a low-risk PESI score and 24% of the discharged patients were high-risk PESI. 30-day readmission rate was 22.9% vs 5.3% (p=0.002) in discharged patients with high-risk PESI vs. discharged patients with low-risk PESI. Hypoxemia was the most common (62%) justification for admission in low-risk PESI groups. Among discharged patients we noted an 8.6% 90-day mortality in the high-risk vs. 0% in the low-risk PESI groups. Conclusion: Discharging a PE patient from the ED with a high PESI score carries a significant risk of ED revisit and readmission. Hypoxia was the reason for admission in majority of low risk PE patients.